MRCP Revision Notes

Essential

Revision Notes

for MRCP

Third Edition

Contents

Contributors toThird Edition vii

Contributors to Second Edition ix

Preface to theThird Edition xi

CHAPTER

1. Cardiology 1

J Paisey

2. Clinical Pharmacology,Toxicology and Poisoning 53

S Waring

3. Dermatology 73

H Robertshaw

4. Endocrinology 91

C Dayan

5. Epidemiology 125

G Whitlock

6. Gastroenterology 139

J Ramesh

7. Genetics 179

E Burkitt Wright

8. Genito-urinaryMedicine andAIDS 197

B Goorney

9. Haematology 211

K Patterson

10. Immunology 249

M J McMahon

11. InfectiousDiseases andTropical Medicine 265

C van Halsema

12. Maternal Medicine 291

L Byrd

13. Metabolic Diseases 317

Smeeta Sinha

v

14. MolecularMedicine 353

K Siddals

15. Nephrology 389

P Kalra

16. Neurology 447

G Rees

17. Ophthalmology 483

K Smyth

18. Psychiatry 501

E Sampson

19. RespiratoryMedicine 527

D Wales

20. Rheumatology 569

M J McMahon

21. Statistics 593

A Wade

Index 607

Contents

vi

Chapter 1Cardiology

CONTENTS

1.1 Clinical examination1.1.1 Jugular venous pulse (JVP)1.1.2 Arterial pulse associations1.1.3 Cardiac apex1.1.4 Heart sounds

1.2 Cardiac investigations1.2.1 Electrocardiography (ECG)1.2.2 Echocardiography1.2.3 Nuclear cardiology: myocardial

perfusion imaging (MPI)1.2.4 Cardiac catheterisation1.2.5 Exercise stress testing1.2.6 24-hour ambulatory blood

pressure monitoring1.2.7 Computed tomography (CT)1.2.8 Magnetic resonance imaging

(MRI)

1.3 Valvular disease andendocarditis1.3.1 Murmurs1.3.2 Mitral stenosis1.3.3 Mitral regurgitation (MR)1.3.4 Aortic regurgitation (AR)1.3.5 Aortic stenosis (AS)1.3.6 Tricuspid regurgitation (TR)1.3.7 Prosthetic valves1.3.8 Infective endocarditis

1.4 Congenital heart disease1.4.1 Atrial septal defect (ASD)1.4.2 Ventricular septal defect (VSD)1.4.3 Patent ductus arteriosus (PDA)1.4.4 Coarctation of the aorta1.4.5 Eisenmenger syndrome1.4.6 Tetralogy of Fallot1.4.7 Important post-surgical

circulation

1.5 Arrhythmias and pacing1.5.1 Bradyarrhythmias1.5.2 Supraventricular tachycardias1.5.3 Atrial arrhythmias1.5.4 Ventricular arrhythmias and

channelopathies1.5.5 Pacing and ablation procedures

1.6 Ischaemic heart disease1.6.1 Angina1.6.2 Myocardial infarction1.6.3 Medical therapy for myocardial

infarction1.6.4 Coronary artery interventional

procedures

1

1.7 Othermyocardial diseases1.7.1 Cardiac failure1.7.2 Hypertrophic cardiomyopathy

(HCM)1.7.3 Dilated cardiomyopathy (DCM)1.7.4 Restrictive cardiomyopathy1.7.5 Myocarditis1.7.6 Cardiac tumours1.7.7 Alcohol and the heart1.7.8 Cardiac transplantation

1.8 Pericardial disease1.8.1 Constrictive pericarditis1.8.2 Pericardial effusion1.8.3 Cardiac tamponade

1.9 Disorders of major vessels1.9.1 Pulmonary hypertension1.9.2 Venous thrombosis and

pulmonary embolism1.9.3 Systemic hypertension1.9.4 Aortic dissection

Appendix INormal cardiac physiological values

Appendix IISummary of further trials in cardiology

Essential Revision Notes for MRCP

2

Cardiology

1.1 CLINICAL EXAMINATION

1.1.1 Jugular venous pulse (JVP)

This reflects the right atrial pressure (normal to 3 cmabove the clavicle with the subject at 458). Thisshould fall with inspiration, which increases venousreturn by a suction effect of the lungs, and withexpansion of the pulmonary beds. However, if theneck veins are distended by inspiration this impliesthat the right heart chambers cannot increase in sizedue to restriction by fluid or pericardium: Kuss-maul’s sign. Non-pulsatile JVP elevation occurs withsuperior vena caval obstruction.

Normal waves in the JVP

a waveDue to atrial contraction – active push up superiorvena cava (SVC) and into the right ventricle (maycause an audible S4).

c waveAn invisible flicker in the x descent due to closureof the tricuspid valve, before the start of ventricularsystole.

x descentDownward movement of the heart causes atrialstretch and a drop in pressure.

v waveDue to passive filling of blood into the atriumagainst a closed tricuspid valve.

y descentOpening of the tricuspid valve with passive move-ment of blood from the right atrium to the rightventricle (causing an S3 when audible).

Pathological waves in the JVP

a wavesLost in atrial fibrillation, giant in tricuspid stenosis

or in pulmonary hypertension with sinus rhythm(atrial septal defect (ASD) will exaggerate the natur-al a and v waves in sinus rhythm).

Giant v(s) wavesMerging of the a and v waves into a large wave(with a rapid y descent) as pressure continues toincrease due to ventricular systole in patients withtricuspid regurgitation.

Steep x descentsOccur in states where there is atrial filling only dueto ventricular systole and downward movement ofthe base of the heart, ie compressed atrial stateswith tamponade or constrictive pericarditis.

Rapid y descentOccurs in states where high flow occurs with tricus-pid valve opening (eg tricuspid regurgitation (highatrial load) or constrictive pericarditis) – vacuumeffect. A slow y descent indicates tricuspid stenosis.

Cannon a wavesAtrial contractions against a closed tricuspid valvedue to a nodal rhythm, a ventricular tachycardia,ventricular-paced rhythm (regular), complete heartblock or ventricular extrasystoles (irregular). Theyoccur regularly but not consistently in type 1second-degree heart block.

1.1.2 Arterial pulse associations

• Collapsing: aortic regurgitation, arteriovenousfistula, patent ductus arteriosus or other largeextra-cardiac shunt

• Slow rising: aortic stenosis (delayed percussionwave)

• Bisferiens: a double shudder due to mixedaortic valve disease with significantregurgitation (tidal wave second impulse)

• Jerky: hypertrophic obstructive cardiomyopathy• Alternans: severe left ventricular failure

Cardiology

3

• Paradoxical (pulsus paradoxus): an excessivereduction in the pulse with inspiration (drop insystolic BP .10 mmHg) occurs with leftventricular compression, tamponade,constrictive pericarditis or severe asthma asvenous return is compromised

Causes of an absent radial pulse

• Dissection of the aorta with subclavianinvolvement

• Iatrogenic: post-catheterisation• Peripheral arterial embolus• Takayasu’s arteritis• Trauma

1.1.3 Cardiac apex

An absent apical impulse

The apex may be impalpable in the following situa-tions:

• Obesity/emphysema• Right pneumonectomy with displacement• Pericardial effusion or constriction• Dextrocardia (palpable on right side of chest)

Apex associations

Palpation of the apex beat (reflecting counter-clock-wise ventricular movement striking the chest wall

during isovolumic contractions) can detect the fol-lowing pathological states:

• Heaving: left ventricular hypertrophy (LVH) (andall its causes), sometimes associated withpalpable fourth heart sound

• Thrusting/hyperdynamic: high left ventricularvolume (eg in mitral regurgitation, aorticregurgitation, patent ductus arteriosus (PDA),ventricular septal defect)

• Tapping: palpable first heart sound in mitralstenosis

• Displaced and diffuse/dyskinetic: leftventricular impairment and dilatation (eg dilatedcardiomyopathy, myocardial infarction (MI))

• Double impulse: with dyskinesia is due to leftventricular aneurysm; without dyskinesia inhypertrophic cardiomyopathy (HCM)

• Pericardial knock: constrictive pericarditis• Parasternal heave: due to right ventricular

hypertrophy (eg ASD, pulmonary hypertension,chronic obstructive pulmonary disease (COPD),pulmonary stenosis)

• Palpable third heart sound: due to heart failureand severe mitral regurgitation

1.1.4 Heart sounds

Abnormalities of first heart sounds are given inTable 1.1 and of second heart sounds are given inTable 1.2.

Table 1.1. Abnormalities of the first heart sound (S1): closure of mitral and tricuspid valves

Loud Soft Split Variable

Mobile mitral stenosis Immobile mitral stenosis RBBB Atrial fibrillationHyperdynamic states Hypodynamic states LBBB Complete heart blockTachycardic states Mitral regurgitation VTLeft-to-right shunts Poor ventricular function InspirationShort PR interval Long PR interval Ebstein’s anomaly

LBBB, left bundle branch block; RBBB, right bundle branch block; VT, ventricular tachycardia


4

Third heart sound (S3)

Due to the passive filling of the ventricles on open-ing of the AV valves, audible in normal childrenand young adults. Pathological in cases of rapid leftventricular filling (eg mitral regurgitation, ventricularseptal defect (VSD), congestive cardiac failure andconstrictive pericarditis).

Fourth heart sound (S4)

Due to the atrial contraction that fills a stiff leftventricle, such as in LVH, amyloid, HCM and leftventricular ischaemia. It is absent in atrial fibrilla-tion.

Causes of valvular clicks

• Aortic ejection: aortic stenosis, bicuspid aorticvalve

• Pulmonary ejection: pulmonary stenosis• Mid-systolic: mitral valve prolapse

Opening snap (OS)

In mitral stenosis an OS can be present and occursafter S2 in early diastole. The closer it is to S2 the

greater the severity of mitral stenosis. It is absentwhen the mitral cusps become immobile due tocalcification, as in very severe mitral stenosis.

1.2 CARDIAC INVESTIGATIONS

1.2.1 Electrocardiography (ECG)

Both the axis and sizes of QRS vectors give impor-tant information. Axes are defined:

• –308 to +908: normal• –308 to –908: left axis• +908 to +1808: right axis• –908 to –1808: indeterminate

Tip – if the QRS is positive in leads 1 and aVF theaxis is normal.

The causes of common abnormalities are given inthe box on p. 7. ECG strips illustrating typicalchanges in common disease states are shown inFigure 1.1.

Table 1.2. Abnormalities of the second heart sound (S2): closure of aortic then pulmonary valves

(,0.05 s apart)

Intensity Splitting

Loud: Fixed: Single S2:Systemic hypertension (loud A2)Pulmonary hypertension (loud P2)

ASD Severe pulmonary stenosis/aortic stenosisHypertension

Tachycardic states Widely split: Large VSDASD (loud P2) RBBB Tetralogy of Fallot

Pulmonary stenosis Eisenmenger syndromeSoft or absent: Deep inspiration Pulmonary atresiaSevere aortic stenosis Mitral regurgitation Elderly

Reversed split S2:LBBBRight ventricular pacingPDAAortic stenosis

A2, aortic second sound; ASD, atrial septal defect; LBBB, left bundle branch block; P2, pulmonary second sound;PDA, patent ductus arteriosus; RBBB, right bundle branch block; VSD, ventricular septal defect

Cardiology

5

Figure

1.1

ECG

stripsdemonstratingtypicalch

anges

inco

mmondiseasestates


6

Causes of common abnormalities in the

ECG

• Causes of left axis deviation• Left bundle branch block (LBBB)• Left anterior hemi-block (LAHB)• LVH• Primum ASD• Cardiomyopathies• Tricuspid atresia

• Low-voltage ECG• Pulmonary emphysema• Pericardial effusion• Myxoedema• Severe obesity• Incorrect calibration• Cardiomyopathies• Global ischaemia• Amyloid

• Causes of right axis deviation• Infancy• Right bundle branch block (RBBB)• Right ventricular hypertrophy (eg lung

disease, pulmonary embolism, largesecundum ASD, severe pulmonarystenosis, tetralogy of Fallot)

• Abnormalities of ECGs in athletes• Sinus arrhythmia• Sinus bradycardia• First-degree heart block• Wenckebach phenomenon• Junctional rhythm

Clinical diagnoses which can bemade from

the ECG of an asymptomatic patient

• Atrial fibrillation• Complete heart block• HCM• ASDs (with RBBB)• Long QT and Brugada syndromes• Wolff–Parkinson–White (WPW) syndrome

(delta waves)• Arrhythmogenic right ventricular dysplasia

(cardiomyopathy)

Short PR interval

This is rarely less than 0.12 s; the most commoncauses are those of pre-excitation involving acces-sory pathways or of tracts bypassing the slow regionof the atrioventricular (AV) node; other causes doexist.

• Pre-excitation• WPW syndrome• Lown–Ganong–Levine syndrome (short

PR syndrome)• Other

• Ventricular extrasystole falling afterP wave

• AV junctional rhythm (but P wave willusually be negative)

• Low atrial rhythm• Coronary sinus escape rhythm• Normal variant (especially in the young)

Causes of tall Rwaves inV1

It is easy to spot tall R waves in V1. This lead largelyfaces the posterior wall of the left ventricle (LV) andthe mass of the right ventricle. As the overall vectoris predominantly towards the bulkier LV in normalsituations, the QRS is usually negative in V1. Thisbalance can be reversed in the following situations:

• Right ventricular hypertrophy (myriad causes)• RBBB• Posterior infarction• Dextrocardia• WPW syndrome with left ventricular pathway

insertion (often referred to as type A)• HCM (septal mass greater than posterior wall)

Bundle branch block and ST-segment

abnormalities

Complete bundle branch block is a failure or delayof impulse conduction to one ventricle from the AVnode, requiring conduction via the other bundle,and then transmission within the ventricular myo-cardium; this results in abnormal prolongation ofQRS duration (>120 ms) and abnormalities of the

Cardiology

7

normally isoelectric ST segment. In contrast toRBBB, LBBB is always pathological.

• Causes of LBBB• Ischaemic heart disease (recent or old

MI)• Hypertension• LVH• Aortic valve disease• Cardiomyopathy• Myocarditis• Post-valve replacement• Right ventricular pacemaker• Tachycardia with aberrancy or

concealed conduction• Ventricular ectopy

• Causes of RBBB• Normal in the young• Right ventricular strain (eg pulmonary

embolus)• ASD• Ischaemic heart disease• Myocarditis• Idiopathic• Tachycardia with aberrancy or

concealed conduction• Ventricular ectopy

• Causes of ST elevation• Early repolarisation• Acute MI• Pericarditis (saddle-shaped)• Ventricular aneurysm• Coronary artery spasm• During angioplasty• Non-standard ECG acquisition settings

(eg on monitor)• Other ST-T wave changes (not elevation)

• Ischaemia: ST depression,T inversion andpeaking

• Digoxin therapy: downslopingST depression

• Hypertrophy: ST depression,T inversion

• Post-tachycardia: ST depression,T inversion

• Hyperventilation: ST depression,T inversion andpeaking

• Oesophageal/upper abdominalirritation:

ST depression,T inversion

• Cardiac contusion: ST depression,T inversion

• Mitral valve prolapse:T wave inversion

• Acute cerebral event(eg subarachnoid haemorrhage):

ST depression,T inversion

• Electrolyte abnormalities

Q waves can be permanent (reflecting myocardialnecrosis) or transient (suggesting failure of myocar-dial function, but not necrosis).

• Permanent Q waves• Transmural infarction• LBBB• WPW syndrome• HCM• Idiopathic cardiomyopathy• Amyloid heart disease• Neoplastic infiltration• Friedreich’s ataxia• Dextrocardia• Sarcoidosis• Progressive muscular dystrophy• Myocarditis (may resolve)

• Transient Q waves• Coronary spasm• Hypoxia• Hyperkalaemia• Cardiac contusion• Hypothermia


8

Potassium and ECG changes

There is a reasonable correlation between plasmapotassium and ECG changes.

• Hyperkalaemia• Tall T waves• Prolonged PR interval• Flattened/absent P waves

• Very severe hyperkalaemia• Wide QRS• Sine wave pattern• Ventricular tachycardia/ventricular

fibrillation/asystole• Hypokalaemia

• Flat T waves, occasionally inverted• Prolonged PR interval• ST depression• Tall U waves

ECG changes following coronary artery

bypass surgery

• U waves (hypothermia)• Saddle-shaped ST elevation (pericarditis)• PR-segment depression (pericarditis)• Low-voltage ECG in chest leads (pericardial

effusion)• Changing electrical alternans (alternating ECG

axis – cardiac tamponade)• S1Q3T3 (pulmonary embolus)• Atrial fibrillation• Q waves• ST-segment and T-wave changes

Electrocardiographic techniques for

prolongedmonitoring

• Holter monitoring: the ECG is monitored in oneor more leads for 24–72 h. The patient isencouraged to keep a diary in order to correlatesymptoms with ECG changes

• External recorders: the patient keeps a monitorwith them for a period of days or weeks. At theonset of symptoms the monitor is placed to thechest and this records the ECG

• Wearable loop recorders: the patient wears amonitor for several days or weeks. The device

records the ECG constantly on a self-erasingloop. At the time of symptoms, the patientactivates the recorder and a trace spanningsome several seconds before a period ofsymptoms to several minutes afterwards isstored

• Implantable loop recorders: a loop recorder isimplanted subcutaneously in the pre-pectoralregion. The recorder is activated by the patientor according to pre-programmed parameters.Again the ECG data from several seconds beforesymptoms to several minutes after are stored;data are uploaded by telemetry. The battery lifeof the implantable loop recorder is approx-imately 18 months

1.2.2 Echocardiography

Principles of the technique

Sound waves emitted by a transducer are reflectedback differentially by tissues of variable acousticproperties. Moving structures (including fluid struc-tures) reflect sound back as a function of their ownvelocity. The signal-to-noise ratio is improved byminimising the distance and number of acousticstructures between the transducer and the objectbeing recorded.

A longitudinal beam differentiating structures byreflectivity plotted against time gives an M-modeimage. Allows accurate measurement of dimen-sions, eg LA size, end-diastolic dimension.

A longitudinal beam measuring velocities gives aDoppler velocity – a continuous wave picks up thegreatest velocity along the line, a pulsed wavefocuses on a specific point and tissue Doppler on afixed point of myocardium. Velocities can be usedto calculate pressure gradients. Used to measurevalve gradients and wall motion parameters.

A broad beam gives a two-dimensional movingimage that can be processed into a three-dimensional image with appropriate echo probeand processing software. The standard windowspermit imaging of the cardiac chambers to assessstructural abnormalities and function.

Cardiology

9

Sampling multiple velocities within a two-dimen-sional image and assigning colours to the positiveand negative velocities gives a visual image ofcolour flow mapping. Ideal for assessing valvularregurgitation.

Diagnostic uses of echocardiography

Conventional echocardiography is used in the diag-nosis of:

• Pericardial effusion and tamponade• Valvular disease (including large vegetations)• HCM, dilated cardiomyopathy, LV mass and

function• Cardiac tumours and intracardiac thrombus• Congenital heart disease (eg PDA; coarctation of

the aorta)• Right ventricular function and pressure

Stress echo is used in the diagnosis of myocardialviability and ischaemia.

Standard contrast echo is used in the diagnosis ofright-to-left shunts, especially ASD/VSD.

Transpulmonary contrast echo is used to improvediscrimination between the blood pool and theendocardium to improve definition in those subjectswhose characteristics lead to poor image quality. Itis also used to diagnose LV thrombus and otherspecific conditions (eg the congenital failure ofmuscle fibre alignment (known as non-compaction)and apical hypertrophy).

Tissue Doppler imaging is used to improve theaccuracy of LV wall motion assessments.

Three-dimensional echo is used to investigate con-genital heart disease and in valve studies; it also hasresearch applications.

Transoesophageal echocardiography (TOE) is indi-cated in the diagnosis of aortic dissection, suspectedatrial thrombus, the assessment of vegetations orabscesses in endocarditis, prosthetic valve dysfunc-tion or leakage, intraoperative assessment of LVfunction, and where there is a technically sub-optimal transthoracic echocardiogram.

Intravascular ultrasound gives high-resolutionimages of coronary arteries; it is useful in assessingplaque size and in stent deployment.

Intracardiac ultrasound images the heart chambersfrom within; it is used mainly in those with congeni-tal heart disease and in electrophysiological proce-dures.

Classic M-modepatterns

Due to improvements in real-time image quality M-mode imaging is now used less in clinical practice;it does, however, allow interpretable traces to beprinted as still images, and these still occasionallyfeature in exams. Particular M-mode patterns thathave been used in past MRCP exams include:

• Aortic regurgitation: fluttering of the anteriormitral leaflet is seen

• HCM: systolic anterior motion (SAM) of themitral valve leaflets and asymmetrical septalhypertrophy (see Figure 1.2)

• Mitral valve prolapse: one or both leafletsprolapse during systole

• Mitral stenosis: the opening profile of the cuspsis flat and multiple echoes are seen when thereis calcification of the cusps

1.2.3 Nuclear cardiology: myocardialperfusion imaging (MPI)

Perfusion tracers such as thallium or technetium canbe used to gauge myocardial blood flow, both atrest and during exercise- or drug-induced stress.Tracer uptake is detected using tomograms anddisplayed in a colour scale in standard views.

Lack of uptake may be:

• Physiological: due to lung or breast tissueabsorption

• Pathological: reflecting ischaemia, infarction orother conditions in which perfusionabnormalities also occur (eg HCM oramyloidosis)

Pathological perfusion defects are categorised asfixed (scar) and reversible (viable but ischaemictissue).


10

MPI can be used to:

• Detect infarction• Investigate atypical chest pains• Assess ventricular function• Determine prognosis and detect myocardium

that may be ‘re-awakened’ from hibernationwith an improved blood supply (eg aftercoronary artery bypass grafting (CABG))

1.2.4 Cardiac catheterisation

Coronary and ventricular angiography

Direct injection of radio-opaque contrast into thecoronary arteries allows high-resolution assessmentof restrictive lesions and demonstrates any anoma-lies. Left ventriculography provides a measure ofventricular systolic function.

Aortography in cardiac diagnoses

Improved availability and resolution of cross-sectional imaging techniques have greatly reducedthe need for diagnostic aortography.

The following can be identified with an aortogram:

• AR• Coarctation of the aorta• Aortic dissection

• PDA• Aberrant subclavian arteries• Aortic root abscess• Coronary artery anomalies• Paraprosthetic AR• Bypass grafts• Aortic root dilatation (eg Marfan syndrome)

Right heart catheterisation

Catheterisation of the right heart chambers andpulmonary artery (PA) can be undertaken as a wardinvestigation using a Swan–Ganz flotation catheteror as part of an X-ray-fluoroscopy-guided cathlabstudy.

It allows right ventricular and PA angiography, anddirect pressure and saturation measurements of theright atrium (RA), right ventricle (RV) and PA. Wed-ging the catheter in small arteries prevents forwardpressure from being transmitted, so the transducermeasures the pressure of the pulmonary capillarybed, which is equal to pulmonary venous pressure.

In the cathlab initial manoeuvres such as simultane-ous LV catheterisation and contrast injection add tothe diagnostic value of the procedure: a gradientbetween pulmonary wedge (PV) pressure and leftventricular end-diastolic pressure (LVEDP) quantifiesmitral stenosis (usually previously diagnosed by

Figure 1.2 Classic valvular disease patterns seen with M-mode echocardiography

Cardiology

11

echocardiography) and direct pulmonary angio-graphy can be performed. Direct pulmonary angio-graphy has now been largely replaced by CTangiography.

Complications of cardiac catheterisation

Complications are uncommon (approximately 5%,including minor complications); these include con-trast allergy, local haemorrhage from puncture siteswith subsequent occurrence of thrombosis, falseaneurysm or arteriovenous (AV) malformation. Vaso-vagal reactions are common. Other complicationsare:

• Coronary dissection (particularly the rightcoronary artery in women) and aortic dissectionor ventricular perforation

• Air or atheroma embolism: in the coronary orother arterial circulations, with consequentischaemia or strokes

• Ventricular dysrhythmias: can even cause deathin the setting of left main stem disease

• Mistaken cannulation and contrast injection intothe conus branch of the right coronary arterycan cause ventricular fibrillation

• Overall mortality rates are quoted at ,1/1000cases

1.2.5 Exercise stress testing

This is used in the investigation of coronary arterydisease, in exertion-induced arrhythmias, and in theassessment of cardiac workload and conductionabnormalities. Exercise tests also give diagnosticand prognostic information post-infarction, and gen-erate patient confidence in rehabilitation after MI.Diagnostic sensitivity is improved if the test is con-ducted with the patient having discontinued anti-anginal (especially rate-limiting) medication.

The main contraindications to exercise testing in-clude those conditions where fatal ischaemia orarrhythmias may be provoked, or where exertionmay severely and acutely impair cardiac function.

These include the following:

• Severe aortic stenosis or HCM with markedoutflow obstruction

• Acute myocarditis or pericarditis• Pyrexial or coryzal illness• Severe left main stem disease• Untreated congestive cardiac failure• Unstable angina• Dissecting aneurysm• Ongoing tachy- or bradyarrhythmias• Untreated severe hypertension

Indicators of a positive exercise test result

The presence of each factor is additive in the overallpositive prediction of coronary artery disease:

• Development of anginal symptoms• A fall in BP of .15 mmHg or failure to increase

BP with exercise• Arrhythmia development (particularly

ventricular)• Poor workload capacity (may indicate poor left

ventricular function)• Failure to achieve target heart rate (allowing for

â-blockers)• .1 mm down-sloping or planar ST-segment

depression, 80 ms after the J point• ST-segment elevation• Failure to achieve 9 min of the Bruce protocol

due to any of the points listed

Exercise tests have low specificity in the followingsituations (often as a result of resting ST-segmentabnormalities):

• Ischaemia in young women with atypical chestpains

• Atrial fibrillation• LBBB• WPW syndrome• LVH• Digoxin or â-blocker therapy• Anaemia• Hyperventilation• Biochemical abnormalities such as

hypokalaemia


12

1.2.6 24-hour ambulatory bloodpressure monitoring

The limited availability and relative expense ofambulatory blood pressure monitoring prevents itsuse in all hypertensive patients. Specific areas ofusefulness include the following situations:

• Assessing for ‘white coat’ hypertension• Borderline hypertensive cases that may not need

treatment• Evaluation of hypotensive symptoms• Identifying episodic hypertension (eg in

phaeochromocytoma)• Assessing drug compliance and effects

(particularly in resistant cases)• Nocturnal blood pressure dipper status (non-

dippers are at higher risk)

1.2.7 Computed tomography (CT)

CT has theoretical capability in both anatomical(coronary arteries, chamber dimension, pericar-dium) and functional (contractility, ischaemia, viabi-lity) assessments of the heart. It is the gold standardinvestigation for:

• Pulmonary thromboembolic disease• Anatomical assessment of the pericardium (eg in

suspected constriction)• Anomalous coronary artery origins (reliable

imaging of the proximal third of major coronaryarteries)

• Extramyocardial mediastinal masses

Other indications include assessment of:

• Chamber dimensions• Myocardial function, perfusion and ischaemia

1.2.8 Magnetic resonance imaging(MRI)

Cardiac MRI is the gold standard technique forassessment of myocardial function, ischaemia, per-fusion and viability, cardiac chamber anatomy andimaging of the great vessels. It has a useful adjunc-tive role in pericardial/mediastinal imaging. Majordrawbacks are its contraindication in patients with

certain implanted devices (eg pacemakers) andtime (consequently also cost), as a full functionalstudy can take about 45 minutes. The contrast used(gadolinium), while not directly nephrotoxic, is sub-ject to increased risk of metabolic toxicity in renallyimpaired individuals.

Chief indications of cardiac MRI:

• Myocardial ischaemia and viability assessment• Differential diagnosis of structural heart disease

(congenital and acquired)• Chamber anatomy definition• Initial diagnosis and serial follow-up of great

vessel pathology (especially aortopathy)• Pericardial and mediastinal structural assessment

1.3 VALVULAR DISEASE ANDENDOCARDITIS

1.3.1 Murmurs

Benign flow murmurs: soft, short systolic murmursheard along the left sternal edge to the pulmonaryarea, without any other cardiac auscultatory, ECGor chest X-ray abnormalities. Thirty per cent ofchildren may have an innocent flow murmur.

Cervical venous hum: continuous when upright andis reduced by lying; occurs with a hyperdynamiccirculation or with jugular vein compression.

Large AV fistula of the arm: may cause a harsh flowmurmur across the upper mediastinum.

Effect of posture on murmurs: standing significantlyincreases the murmurs of mitral valve prolapse andHCM only. Squatting and passive leg raising in-crease cardiac afterload and therefore decrease themurmur of HCM and mitral valve prolapse, whilstincreasing most other murmurs such as ventricularseptal defect, aortic, mitral and pulmonary regurgi-tation, and aortic stenosis.

Effect of respiration on murmurs: inspiration ac-centuates right-sided murmurs by increasing venousreturn, whereas held expiration accentuates left-sided murmurs. The strain phase of a Valsalvamanoeuvre reduces venous return, stroke volume

Cardiology

13

and arterial pressure, decreasing all valvular mur-murs but increasing the murmur of HCM and mitralvalve prolapse.

Classi¢cation of murmurs

• Mid-/late systolic murmurs• Innocent murmur• Aortic stenosis or sclerosis• Coarctation of the aorta• Pulmonary stenosis• HCM• Papillary muscle dysfunction• ASD (due to high pulmonary flow)• Mitral valve prolapse

• Mid-diastolic murmurs• Mitral stenosis or ‘Austin Flint’ due to

aortic regurgitant jet• Carey Coombs (rheumatic fever)• High AV flow states (ASD, VSD, PDA,

anaemia, mitral regurgitation, tricuspidregurgitation)

• Atrial tumours (particularly if causingAV flow disturbance)

• Continuous murmurs• PDA• Ruptured sinus of Valsalva aneurysm• ASD• Large AV fistula• Anomalous left coronary artery• Intercostal AV fistula• ASD with mitral stenosis• Bronchial collaterals

1.3.2 Mitral stenosis

Two-thirds of patients presenting with this arewomen. The most common cause remains chronicrheumatic heart disease; rarer causes includecongenital disease, carcinoid, systemic lupuserythematosus (SLE) and mucopolysaccharidoses(glycoprotein deposits on cusps). Stenosis may oc-cur at the cusp, commissure or chordal level.

• Anticoagulation for atrial fibrillation protectsfrom 173 increased risk of thromboembolism

Features of severe mitral stenosis

• Symptoms• Dyspnoea with minimal activity• Haemoptysis• Dysphagia (due to left atrium

enlargement)• Palpitations due to atrial fibrillation

• Chest X-ray• Left atrial or right ventricular

enlargement• Splaying of subcarinal angle (.908)• Pulmonary congestion or hypertension• Pulmonary haemosiderosis

• Echo• Doming of leaflets• Heavily calcified cusps• Direct orifice area ,1.0 cm2

• Signs• Low pulse pressure• Soft first heart sound• Long diastolic murmur and apical thrill

(rare)• Very early opening snap, ie closer to S2

(lost if valves immobile)• Right ventricular heave or loud P2• Pulmonary regurgitation (Graham Steell

murmur)• Tricuspid regurgitation

• Cardiac catheterisation• Pulmonary capillary wedge end diastole

to left ventricular end-diastolic pressure(LVEDP) gradient .15 mmHg

• Left atrium (LA) pressures .25 mmHg• Elevated RV and PA pressures• High pulmonary vascular resistance• Cardiac output ,2.5 l min–1 m–2 with

exercise


14

Mitral balloon valvuloplasty

Valvuloplasty using an Inoue balloon requires eithera trans-septal or a retrograde approach and is usedonly in suitable cases where echo shows that:

• The mitral leaflet tips and valvular chordae arenot heavily thickened, distorted or calcified

• The mitral cusps are mobile at the base• There is minimal or no mitral regurgitation• There is no left atrial thrombus seen on TOE

1.3.3 Mitral regurgitation (MR)

The full structure of the mitral valve includes theannulus, cusps, chordae and papillary musculature,and abnormalities of any of these can cause regur-gitation. The presence of symptoms and increasingleft ventricular dilatation are indicators for surgeryin the chronic setting. Operative mortalities are2%–7% for valvular replacements in patients withNYHA grade II–III symptoms. Various techniqueshave revolutionised mitral valve surgery, transform-ing outcomes from being no better than medicaltherapy with replacement to almost normal withrepair. In skilled surgical hands the repair is tailoredto the precise anatomical abnormality.

Functional MR is a term used to describe MR that isdue to stretching of the annulus secondary to ven-tricular dilatation.

Main causes of MR

• Myxomatous degeneration• Functional, secondary to ventricular

dilatation• Mitral valve prolapse• Ischaemic papillary muscle rupture• Congenital heart diseases• Collagen disorders• Rheumatic heart disease• Endocarditis

Indicators of the severity ofMR

• Small-volume pulse

• Left ventricular enlargement due to overload• Presence of S3• Atrial fibrillation• Mid-diastolic flow murmur• Precordial thrill, signs of pulmonary

hypertension or congestion (cardiac failure)

Signs of predominant MR inmixedmitral

valve disease

• Soft S1; S3 present• Displaced and hyperdynamic apex (left

ventricular enlargement)• ECG showing LVH and left axis deviation

Mitral valve prolapse

This condition occurs in 5% of the population andis commonly over-diagnosed (depending on theechocardiography criteria applied). The patients areusually female and may present with chest pains,palpitations or fatigue, although it is often detectedincidentally in asymptomatic patients. Squatting in-creases the click and standing increases the mur-mur, but the condition may be diagnosed in theabsence of the murmur by echo. Often there ismyxomatous degeneration and redundant valvetissue due to deposition of acid mucopolysacchar-ide material. Antibiotic prophylaxis before dentalor surgical interventions should be recommendedfor those with a murmur. Mitral valve prolapse isusually eminently suitable for mitral valve repairalthough this should only be undertaken if theseverity of the regurgitation associated with thecondition justifies it (see above). Several conditionsare associated with mitral valve prolapse (see over-leaf), and patients with the condition are prone tocertain sequelae.

Sequelae of mitral valve prolapse:

• Embolic phenomena• Rupture of mitral valve chordae• Dysrhythmias with QT prolongation• Sudden death• Cardiac neurosis

Cardiology

15

Conditions associated with mitral valve

prolapse

• Coronary artery disease• Polycystic kidney disease• Cardiomyopathy – dilated cardiomyopathy/

HCM• Secundum ASD• WPW syndrome• PDA• Marfan syndrome• Pseudoxanthoma elasticum• Osteogenesis imperfecta• Myocarditis• SLE; polyarteritis nodosa• Muscular dystrophy• Left atrial myxoma

1.3.4 Aortic regurgitation (AR)

Patients with severe chronic aortic regurgitation (AR)have the largest end-diastolic volumes of those withany form of heart disease and also have a greaternumber of non-cardiac signs. AR may occur acutely(as in dissection or endocarditis) or chronicallywhen the left ventricle has time to accommodate.

Causes of AR

• Valve inflammation• Chronic rheumatic• Infective endocarditis• Rheumatoid arthritis; SLE• Hurler syndrome

• Aortitis• Syphilis• Ankylosing spondylitis• Reiter syndrome• Psoriatic arthropathy

• Aortic dissection/trauma• Hypertension• Bicuspid aortic valve• Ruptured sinus of Valsalva aneurysm• VSD with prolapse of (R) coronary cusp• Disorders of collagen

• Marfan syndrome (aortic aneurysm)• Hurler syndrome• Pseudoxanthoma elasticum

Eponymous signs associated with AR

• Quincke’s sign – nail-bed fluctuation ofcapillary flow

• Corrigan’s pulse – (waterhammer);collapsing radial pulse

• Corrigan’s sign – visible carotid pulsation• De Musset’s sign – head nodding with each

systole• Duroziez’s sign – audible femoral bruits

with diastolic flow (indicating moderateseverity)

• Traube’s sign – ‘pistol shots’ (systolicauscultatory finding of the femoral arteries)

• Austin Flint murmur – functional mitraldiastolic flow murmur

• Argyll Robertson pupils – aetiologicalconnection with syphilitic aortitis

• Muller’s sign – pulsation of the uvula

Indications for surgery

Acute severe AR will not be tolerated for long by anormal ventricle and therefore requires prompt sur-gery, except in the case of infection, where delayfor antibiotic therapy is preferable (if haemodynamicstability allows). At 10 years, 50% of patients withmoderate chronic AR are alive, but once symptomsoccur deterioration is rapid.


16

Features of AR indicative of the need

for surgery

• Symptoms of dyspnoea/left ventricularfailure• Reducing exercise tolerance

• Rupture of sinus of Valsalva aneurysm• Infective endocarditis not responsive to

medical treatment• Enlarging aortic root diameter in Marfan

syndrome with AR• Enlarging heart

• End-systolic diameter .55 mm at echo• Pulse pressure .100 mmHg• Diastolic pressure ,40 mmHg• Lengthening diastolic murmur• ECG: lateral lead T-wave inversion

1.3.5 Aortic stenosis (AS)

Patients often present with the classic triad of symp-toms: angina, dyspnoea and syncope. Echo andcardiac catheterisation gradients of .60 mmHg areconsidered severe and are associated with a valvearea ,0.5 cm2. The gradient may be reduced in thepresence of deteriorating left ventricular function ormitral stenosis, or significant AR.

• Causes of AS: may be congenital bicuspid valve,degenerative calcification (common in theelderly) and post-rheumatic disease

• Subvalvular: causes of aortic gradients includeHCM and subaortic membranous stenosis, whilesupravalvular stenosis is due to aorticcoarctation, or Williams syndrome (with elfinfacies, mental retardation, hypercalcaemia)

• Sudden death: may occur in AS or insubvalvular stenosis due to ventriculartachycardia. The vulnerability to ventriculartachycardia is due to LVH

• Complete heart block: may be due tocalcification involving the upper ventricularseptal tissue housing the conducting tissue. Thiscan also occur post-operatively (after valvereplacement) due to trauma

• Calcified emboli: can arise in severe calcific AS.• All symptomatic patients should be considered

for surgery: operative mortality for AS ispredominantly related to the absence (2%–8%)or presence (10%–25%) of left ventricularfailure

Indicators of severe AS

• Symptoms of syncope or left ventricularfailure

• Signs of left ventricular failure• Absent A2• Paradoxically split A2• Presence of precordial thrill• S4• Slow-rising pulse with narrow pulse

pressure• Late peaking of long murmur• Valve area ,0.5 cm2 on echocardiography

1.3.6 Tricuspid regurgitation (TR)

Causes of severe TR include the following:

• Functional, due to right ventricular dilatation(commonly co-exists with significant MR)

• Infection. The tricuspid valve is vulnerable toinfection introduced by venous cannulation(iatrogenic or through intravenous drug abuse)

• Carcinoid (nodular hepatomegaly andtelangiectasia)

• Post-rheumatic• Ebstein’s anomaly: tricuspid valve dysplasia with

a more apical position to the valve. Patientshave cyanosis and there is an association withpulmonary atresia or ASD and, less commonly,congenitally corrected transposition

1.3.7 Prosthetic valves

Valve prostheses may be metal or tissue (biopros-thetic). Mechanical valves are more durable buttissue valves do not require full lifelong anti-coagulation. All prostheses must be covered with

Cardiology

17

antibiotic therapy for dental and surgical proce-dures; they have a residual transvalvular gradientacross them.

Mechanical valves

• Starr–Edwards: ball and cage – ejection systolicmurmur (ESM) in the aortic area and an openingsound in the mitral position are normal

• Bjork–Shiley: single tilt disc – audible clickswithout stethoscope

• St Jude (Carbomedics): double tilting discs withclicks

Tissue valves

• Allografts: porcine or bovine three-cusp valve –3 months’ anticoagulation sometimesrecommended until tissue endothelialisation. Noneed for long-term anticoagulation if patient isin sinus rhythm

• Homografts: usually cadaveric and, again, needno long-term anticoagulation

Infection of prosthetic valves

• Mortality is still as high as 60% depending onthe organism

• Within 6 months of implantation, it is usuallydue to colonisation by Staphylococcusepidermidis

• Septal abscesses may cause PR-intervallengthening

• Valvular sounds may be muffled by vegetations;new murmurs may occur

• Mild haemolysis can occur, and is detected bythe presence of urobilinogen in the urine

• Dehiscence is an ominous feature requiringurgent intervention

Anticoagulation in pregnancy

Warfarin may cause fetal haemorrhage and has ateratogenicity risk of 5%–30%. This risk is dose-dependent and abnormalities include chondrodys-plasia, mental impairment, optic atrophy and nasal

hypoplasia. The risk of spontaneous abortion maybe increased. There is no agreed consensus on theideal strategy: warfarin, unfractionated heparin andlow-molecular-weight heparin all have advocatesand detractors.

1.3.8 Infective endocarditis

Clinical presentation

Commonly presents with non-specific symptoms ofmalaise, tiredness and infective-type symptoms.Heart failure secondary to valvular regurgitation orheart block may also occur as may an incidentalpresentation in the context of another primary infec-tion.

Signs of infective endocarditis

As well as cardiac murmurs detected at ausculta-tion, there are several other characteristic features ofinfective endocarditis:

• Systemic signs of fever and arthropathy• Hands and feet: splinter haemorrhages, Osler

nodes (painful), Janeway lesions (painless) andclubbing (late); needle-track signs may occur inarm or groin

• Retinopathy: Roth spots• Hepatosplenomegaly• Signs of arterial embolisation (eg stroke or

digital ischaemia)• Vasculitic rash• Streptococcus viridans (Æ-haemolytic group) are

still the most common organisms, occurring in50% of cases

• Marantic (metastatic-related) and SLE-related(Libman–Sacks) endocarditis are causes of non-infective endocarditis

• Almost any pathogenic organism may beimplicated, particularly in theimmunocompromised patient

See also Section 1.3.7 on ‘Prosthetic valves’ andTable 1.3.


18

Management of infective endocarditis

The aim of treatment is to sterilise the valve medi-cally (usually 4–6 weeks of IV antibiotics) thenassess whether the valvular damage sustained (egdegree of incompetance) or the risk of recurrence(eg if prosthetic valves) mandates surgical replace-ment. Earlier operations are only undertaken ifclincally necessary as outcomes are poorer.

• Poor prognostic factors in endocarditis• Prosthetic valve• Staphylococcus aureus infection• Culture-negative endocarditis• Depletion of complement levels

• Indications for surgery• Cardiac failure or haemodynamic

compromise• Extensive valve incompetence• Large vegetations• Septic emboli• Septal abscess• Fungal infection• Antibiotic-resistant endocarditis• Failure to respond to medical therapy

Antibiotic prophylaxis

The conditions listed in the next box are associatedwith an increased risk of endocarditis.

• Acquired valvular heart disease withstenosis or regurgitation

• Valve replacement• Structural congenital heart disease,

including surgically corrected or palliatedstructural conditions, but excluding isolatedASD, fully repaired VSD or fully repairedPDA, and closure devices that are judgedto be endothelialised

• Previous infective endocarditis• HCM

Antibiotic and chlorhexidine mouthwash prophy-laxis is no longer recommended for dental proce-dures, endoscopies or obstetric procedures.

Patients should be made aware of non-medical risk-prone activities (eg IV drug use, piercings) and thesymptoms of possible endocarditis.

1.4 CONGENITAL HEART DISEASE

Causes of congenital acyanotic heart

disease*

• With shunts• Aortic coarctation (with VSD or PDA)• VSD• ASD• PDA• Partial anomalous venous drainage (with

ASD)• Without shunts

• Congenital AS• Aortic coarctation

*Associated shunts

Table 1.3. Infective endocarditis

Groups affected byendocarditis

% of all cases ofendocarditis

Chronic rheumatic disease 30No previous valve disease 40Intravenous drug abuse 10Congenital defects 10Prosthetic 10

Cardiology

19

Causes of cyanotic heart disease

• With shunts• Tetralogy of Fallot (VSD)• Severe Ebstein’s anomaly (ASD)• Complete transposition of great vessels

(ASD � VSD/PDA)• Without shunts

• Tricuspid atresia• Severe pulmonary stenosis• Pulmonary atresia• Hypoplastic left heart

1.4.1 Atrial septal defect (ASD)

ASDs are the most common congenital defectsfound in adulthood. Rarely, they may present asstroke in young people, due to paradoxical embolusthat originated in the venous system and reachedthe cerebral circulation via right-to-left shunting.Fixed splitting of the second heart sound is thehallmark of an uncorrected ASD. There may be aleft parasternal heave and a pulmonary ESM due toincreased blood flow. There are three main sub-types:

• Secundum (70%): central fossa ovalis defectsoften associated with mitral valve prolapse(10%–20% of cases). ECG shows incomplete orcomplete RBBB with right axis deviation. Notethat a patent foramen ovale (slit-like deficiencyin the fossa ovalis) occurs in up to 25% of thepopulation, but this does not allow equalisationof atrial pressures, unlike ASD

• Primum (15%): sited above the AV valves, oftenassociated with varying degrees of mitral andtricuspid regurgitation and occasionally a VSD,and thus usually picked up earlier in childhood.ECG shows RBBB, left axis deviation, first-degree heart block. Associated with Downsyndrome, Klinefelter syndrome and Noonansyndrome

• Sinus venosus (15%): defect in the upperseptum, often associated with anomalous

pulmonary venous drainage directly into theright atrium

Operative closure is recommended with pulmonary-to-systolic flow ratios above 1.5:1. Closure of secun-dum defects may be performed via cardiac catheter-isation.

Holt–Oram syndrome: (triphalangeal thumb withASD) is a rare syndrome (autosomal dominant withincomplete penetration). It is associated with ab-sence (or reduction anomalies) of the upper arm.

Lutembacher syndrome: a rare combination of anASD with mitral stenosis (the latter is probablyrheumatic in origin).

Investigations for ASDs

Right atrial and right ventricular dilatation may beseen on any imaging technique as may pulmonaryartery conus enlargement. Other characteristic fea-tures are:

• Chest X-ray: pulmonary plethora• Echo: paradoxical septal motion, septal defect

and right-to-left flow of contrast during venousinjection with Valsalva manoeuvre

• Catheterisation: pulmonary hypertension –raised right ventricular pressures and step-up inoxygen saturation between various parts of theright circulation (eg SVC to high right atrium)

Treatment of ASD

There is no specific medical therapy for ASDs; theyare managed by either closure (percutaneous orsurgical) or clinical and echocardiographic follow-up.

Indications for closure:

• Symptoms (dyspnoea)• Systemic embolism• Chamber dilatation• Elevated right heart pressures• Significant left-to-right shunt


20

1.4.2 Ventricular septal defect (VSD)

VSDs are the most common isolated congenitaldefect (2/1000 births; around 30% of all congenitaldefects); spontaneous closure occurs in 30%–50%of cases (usually muscular or membranous types).As with ASDs, closure may be performed via cardi-otomy or percutaneously.

Indications for closure

• Significant left-to-right shunt• Associated with other defect requiring

cardiotomy• Elevated right heart pressure• Endocarditis

• Irreversible pulmonary changes may occur from1 year of age, with vascular hypertrophy andpulmonary arteriolar thrombosis, leading toEisenmenger syndrome

• Parasternal thrill and pansystolic murmur arepresent. The murmur may be ejection systolic invery small or very large defects. With largedefects the aortic component of the secondsound is obscured, or even a single/palpable S2is heard; a mitral diastolic murmur may occur.The apex beat is typically hyperdynamic

Once the Eisenmenger complex develops, the thrilland left sternal edge (LSE) murmur abate and signsare of pulmonary hypertension � regurgitation andright ventricular failure. Surgery should occur earlierto avoid this situation; otherwise a combined heart/lung transplant would be required.

• Other cardiac associations of VSD• PDA (10%)• AR (5%)• Pulmonary stenosis• ASD• Tetralogy of Fallot• Coarctation of the aorta

• Types of VSD• Muscular• Membranous• AV defect• Infundibular• Into the right atrium (Gerbode defect)

1.4.3 Patent ductus arteriosus (PDA)

PDA is common in premature babies, particularlyfemale infants born at high altitude; also if maternalrubella occurs in the first trimester. The connectionoccurs between the pulmonary trunk and the des-cending aorta, usually just distal to the origin of theleft subclavian artery. PDA often occurs with otherabnormalities.

Key features of PDA

• A characteristic left subclavicular thrill• Enlarged left heart and apical heave• Continuous ‘machinery’ murmur• Wide pulse pressure and bounding pulse

Signs of pulmonary hypertension and Eisenmengersyndrome develop in about 5% of cases. Indo-metacin closes the duct in about 90% of babieswhile intravenous prostaglandin E1 may reverse thenatural closure (useful when PDA is associated withcoarctation, hypoplastic left heart syndrome and incomplete transposition of the great vessels, as it willhelp to maintain flow between the systemic andpulmonary circulations). The PDA may also beclosed thoracoscopically or percutaneously.

1.4.4 Coarctation of the aorta

Coarctation can present in infancy with heart failureor in adulthood (third decade) with hypertension,exertional breathlessness or leg weakness. This‘shelf-like’ obstruction of the aortic arch, usuallydistal to the left subclavian artery, is 2–5 times morecommon in males and is responsible for about 7%of congenital heart defects.

Cardiology

21

Treatment is by surgical resection, preferably withend-to-end aortic anastomosis, or by balloon angio-plasty for recurrence after surgery (which occurs in5%–10% of cases). Complications may occur de-spite resection/repair and these include hyper-tension, heart failure, berry aneurysm rupture,premature coronary artery disease and aortic dissec-tion (in the third or fourth decade of life).

Associations of coarctation

• Cardiac• Bicuspid aortic valve (and thus AS �

AR) in 10%–20%• PDA• VSD• Mitral valve disease

• Non-cardiac• Berry aneurysms (circle of Willis)• Turner syndrome• Renal abnormalities

• Signs of coarctation• Hypertension• Radio–femoral delay of arterial pulse• Absent femoral pulses• Mid-systolic or continuous murmur

(infraclavicular)• Subscapular bruits• Rib notching on chest X-ray• Post-stenotic aortic dilatation on chest

X-ray

1.4.5 Eisenmenger syndrome

Reversal of left-to-right shunt, due to massive irre-versible pulmonary hypertension (usually due tocongenital cardiovascular malformations), leads toEisenmenger syndrome. Signs of development in-clude:

• Decrease of original pansystolic (left-to-right)murmur

• Decreasing intensity of tricuspid/pulmonary flowmurmurs

• Single S2 with louder intensity, palpable P2;right ventricular heave

• Appearance of Graham Steell murmur due topulmonary regurgitation

• PSM and ‘v’ waves due to tricuspid regurgitation(TR)

• Clubbing and central cyanosis

Eisenmenger syndrome

• Causes• VSD (the Eisenmenger complex)• ASD• PDA

• Complications of Eisenmenger syndrome• Right ventricular failure• Massive haemoptysis• Cerebral embolism/abscess• Infective endocarditis (rare)

1.4.6 Tetralogy of Fallot

The most common cause of cyanotic congenitalheart disease (10%), usually presenting after age6 months (as the condition may worsen after birth).

Key features

• Pulmonary stenosis (causes the systolicmurmur)

• Right ventricular hypertrophy• VSD• Overriding of the aorta• Right-sided aortic knuckle (25%)

Clinical features

• Cyanotic attacks (pulmonary infundibularspasm)

• Clubbing• Parasternal heave• Systolic thrill• Palpable A2• Soft ejection systolic murmur (inversely

related to pulmonary gradient)• Single S2 (inaudible pulmonary closure)• ECG features of right ventricular

hypertrophy


22

Possible complications of Fallot’s

• Endocarditis• Polycythaemia• Coagulopathy• Paradoxical embolism• Cerebral abscess• Ventricular arrhythmias

• Cyanotic attacks worsen with catecholamines,hypoxia and acidosis. The murmur lessens ordisappears as the right ventricular outflowgradient increases

• Squatting reduces the right-to-left shunt byincreasing systemic vascular resistance; it alsoreduces venous return of acidotic blood fromlower extremities, and hence reducesinfundibular spasm

• The presence of a systolic thrill and an intensepulmonary murmur differentiates the conditionfrom Eisenmenger syndrome

• A Blalock shunt operation results in weakerpulses in the arm from which the subclavianartery is diverted to the pulmonary artery

1.4.7 Important post-surgicalcirculations

Systemic right ventricle

Transposition of the great vessels and similar condi-tions in which the right ventricle supplies the aortaand the left ventricle supplies the pulmonary arteryare now treated by arterial switch. Effectively this isa complete correction.

Prior to the development of the arterial switchprocedure, treatment was by ‘venous redirection’ –the vena cavae redirected via the atria to the leftventricle and the pulmonary veins to the rightventricle via the atria, with the morphological rightventricle then pumping oxygenated blood into theaorta. However, there was a high risk of ventriculardysfunction, valve regurgitation and ventricular ar-rhythmias in these patients and decompensationwould be provoked by development of atrial ar-rhythmias.

Single ventricular circulationIndividuals born with only one functional ventricleare treated by redirecting the vena cavae directlyinto the pulmonary arteries (total cavopulmonarycorrection) and now do very well. Early versions ofthis operation (the classic Fontan) used the rightatrium between the vena cavae, but this often led toatrial dilatation and then fibrillation with a risk ofdecompensation.

Common congenital circulations

Common congenital circulations are summarised inTable 1.4 overleaf.

1.5 ARRHYTHMIAS AND PACING

Atrial fibrillation (AF) remains the most commoncardiac arrhythmia, with incidence increasing withage (Framingham data indicate a prevalence of 76/1000 males and 63/1000 females aged 85–94years). Atrial flutter frequently co-exists with atrialfibrillation, and although it has a different immedi-ate causal mechanism it is a reflection of the sameunderlying disease. These arrhythmias assume parti-cular significance because of the stroke risk asso-ciated with them.

‘SVT’ is the term usually used to indicate a pre-sumed re-entry tachycardia involving the AV nodeor an accessory pathway.

Ventricular tachycardia and ventricular fibrillationare life-threatening conditions, but there is a clearevidence base for the use of implantable cardiover-ter defibrillators in both primary and secondaryprevention (see Appendix II). Anti-arrhythmic drugsor catheter ablation may be useful adjuncts to treat-ment or, in some cases, they can be used asalternatives to defibrillators.

1.5.1 Bradyarrhythmias

Any heart rate below 60 beats per minute is abradycardia. A bradyarrhythmia is a pathologicalbradycardia. Bradyarrhythmias are considered ac-cording to their prognostic significance and sympto-

Cardiology

23

Table

1.4.Commonco

nge

nitalcirculations

Cardinal

features

Pulm

onary

hyp

ertensionVen

tricular

dysfunction

Ven

tricular

arrhythmias

Endoca

rditis

Cyanosis

Atrial

arrhythmiasSystem

icem

bolism

Treatm

entof

choice

VSD

Pansystolic

murm

ur

May

developLa

tefeature

Ifventricle

dilates

Highrisk

inrestrictive

defec

ts

Only

after

shunt

reverses

Percutaneo

usor

surgical

closure

forsign

ificant

shuntor

endocarditis

ASD

Fixedsplit

seco

nd

sound

May

develop

Low

risk

Only

after

shunt

reverses

Atrial

fibrillation,

typical

and

atyp

ical

flutter

Associated

with

parad

oxical

emboli

Percutaneo

usor

surgical

closure

forsign

ificant

shuntorem

boli

PDA

Continuous

murm

ur

May

develop

Highrisk

Only

after

shunt

reverses

Percutaneo

us

closure

Tran

sposition

ofthegreat

vessels

Cyanosis

Ifrigh

tventricle

usedfor

system

iccirculation

Ifventricle

dilates

Earlyfeature

Arterialsw

itch

Single

functioning

ventricle

Cyanosis,

heartfailure

Insome

anatomical

varian

ts

Earlyfeature

Total

cavo

pulm

onary

connection

System

icrigh

tventricle

Post-surgical

or

congenital,

corrected

tran

sposition

Late

feature

After

ventricular

dilatation

Especially

post-surgical

types

of

anatomy

Med

ical

man

agem

entof

heartfailure

and

arrhythmias


24

matic impact. High-grade AV block (Mobitz 2 orcomplete) is associated with sudden death andpatients should be paced urgently even if asympto-matic. Permanent pacing is very effective in redu-cing symptoms in most bradyarrhythmias; theexception is neurocardiogenic syncope where theresults are disappointing.

Common bradyarrhythmias and associated

conditions

Neurocardiogenic symptomsAn exaggerated vasodepressor (hypotension), cardi-oinhibitory (bradycardic) or mixed reflex may causesyncope or presyncope. Various drugs have beentried as treatment, with limited success. In patientswith a predominant cardioinhibitory component,dual chamber pacing may reduce the severity andfrequency of syncopal episodes but results are oftendisappointing.

Sinus node diseaseSinus bradycardia and sinus pauses can causesyncope, presyncope or non-specific symptoms.Thyroid function and electrolytes should bechecked on presentation and corrected prior to con-sidering pacemaker therapy. Pacing is only indi-cated in significantly symptomatic cases (as there isno prognostic benefit of pacing in sinus nodedisease).

First-degree AV blockA PR interval of .200 ms is abnormal but usuallyrequires no treatment. The combinations of first-degree AV block with (1) LBBB, (2) RBBB with axisdeviation or (3) with alternating LBBB and RBBB isinterpreted as trifascicular block (more accuratelyblock in two fascicles and delay in the third). Ifassociated with syncope, trifascicular block repre-sents an indication for pacing on both prognosticand symptomatic grounds.

Second-degree Mobitz 1 (Wenckebach) AVblockProgressive prolongation and then block of the PRinterval is categorised as Mobitz 1. It may benormal during sleep and in young, physically fit

individuals (who have high vagal tone). If it occurswhen the patient is awake and is associated withsymptoms in older people, pacing may be indicatedon symptomatic grounds.

High-grade AV block (second-degree Mobitz 2block and third-degree complete heart block)Bradycardias with more than one P wave per QRScomplex (second-degree Mobitz 2) or with AVdissociation are grouped together as high-grade AVblock. Untreated, they are associated with mortalitythat may exceed 50% at 1 year, particularly inpatients aged over 80 years and in those with non-rheumatic structural heart disease. Pacing is indi-cated on prognostic grounds even in the asympto-matic.

• Complete heart block is the most commonreason for permanent pacing

• When related to an infarction, high-grade AVblock occurs mostly with right coronary arteryocclusion, as the AV nodal branch is usuallyone of the distal branches of the right coronaryartery

• In patients with an anterior infarct, high-gradeAV block is a poor prognostic feature, indicatingextensive ischaemia

• Congenital cases may be related to connectivetissue diseases; however, in patients with normalexercise capacities, recent studies show that theprognosis is not as benign as was previouslythought and pacing is therefore recommendedin a wide range of circumstances (see ESCguidelines by Vardas et al. Eur Heart J, 2007;28:2256–95)

Tachyarrhythmias

Tachyarrhythmias are caused by re-entry, triggeredactivity or automaticity:

• Re-entry – the arrhythmia is anatomicallydependent and usually the primary problem asopposed to sequelae of another reversible state

• Automaticity – arrhythmia is often secondary toa systemic cause (eg electrolyte imbalance,sepsis, adrenergic drive) and is multifocal

Cardiology

25

• Triggered activity – shares features of bothmechanisms and is seen in both primaryarrhythmias and in drug toxicity

1.5.2 Supraventricular tachycardias

There are two major groups of re-entrant tachycar-dias often described as SVT:

• AV nodal re-entry tachycardia (AVNRT):involves a re-entry circuit in and around the AVnode

• AV re-entry tachycardia (AVRT): this involvesan accessory pathway between the atria andventricles some distance from the AV node (egWPW syndrome and related conditions)

AVnodal re-entry tachycardia

Differential conduction in tissue around the AVnode allows a micro re-entry circuit to be main-tained, resulting in a regular tachycardia.

Accessory pathways

An accessory pathway that connects the atrium andventricle mediates the tachycardia by enabling ret-rograde conduction from ventricle to atrium. Moreseriously, the accessory pathway may predispose tounrestricted conduction of AF from atria to ventri-cles as a result of anterograde conduction throughthe pathway. This may lead to ventricular fibrilla-tion.

WPW is said to be present when a delta wave(partial pathway-mediated pre-excitation) is presenton the resting ECG. Associations with WPWinclude: Ebstein’s anomaly (may have multiplepathways), HCM, mitral valve prolapse and thyro-toxicosis; it is more common in men.

Some accessory pathways are not manifest by adelta wave on the resting ECG but are still able toparticipate in a tachycardia circuit.

Atrial tachycardias, including flutter, AF, sinus tachy-cardia and fascicular ventricular tachycardia may allbe mistaken for SVT.

1.5.3 Atrial arrhythmias

Atrial £utter

The atrial rate is usually between 250 and 350beats/min and is often seen with a ventricular re-sponse of 150 beats/min (2:1 block). The block mayvary between a 1:1 ratio and a 1:4 or even a 1:5ratio. Isolated atrial flutter (without atrial fibrillation)has a lower association with thromboembolism;however, recommendations for anticoagulation arethe same as for AF.

• The ventricular response may be slowed byincreasing the vagal block of the AV node (egcarotid sinus massage) or by adenosine, which‘uncovers’ the flutter waves on ECG

• This is the most likely arrhythmia to respond toDC cardioversion with low energies (eg 25 volts)

• Amiodarone and sotalol may chemicallycardiovert, slow the ventricular response or actas prophylactic agents

• Radiofrequency ablation is curative in up to95% of cases

Atrial flutter is described as typical when associatedwith a sawtooth atrial pattern in the inferior leadsand positive flutter waves in V1. Atypical flutterstend to occur in congenital heart disease or aftersurgery or prior ablation.

Atrial ¢brillation (AF)

This arrhythmia is due to multiple wavelet propaga-tion in different directions. The source of the ar-rhythmia may be myocardial tissue in the openingsof the four pulmonary veins, which enter into theposterior aspect of the left atrium, and this is parti-cularly the case in younger patients with paroxys-mal AF. AF may be paroxysmal, persistent (but‘cardiovertable’) or permanent, and in all threestates is a risk factor for strokes. Treatment is aimedat ventricular rate control, cardioversion, recurrenceprevention and anticoagulation. Catheter ablation isindicated in symptomatic individuals who are resis-tant to, or intolerant of, medical therapy.

With AF a major decision is whether to control rate


26

or alter the rhythm:

• Surprisingly, rhythm control does not reduce therisk of stroke (indeed paroxysmal AF carries thesame stroke risk as chronic AF) and thereforedoes not affect the indications foranticoagulation

• Cardioversions, multiple drugs and ablations areall used to alter rhythm

• In asymptomatic individuals rate control isrecommended

Associations with atrial ¢brillation

• Ischaemic heart disease• Pericarditis• Mitral valve disease• Pulmonary embolus• Hypertension• Atrial myxomas• Thyroid disease• LVH• Acute alcohol excess/chronic alcoholic

cardiomyopathy• ASD• Post-coronary artery bypass graft (CABG)• Caffeine excess• Dilated left atrium (.4.5 cm)• Pneumonia• WPW syndrome• Bronchial malignancy

The overall risk of systemic emboli is 5%–7%annually (higher with rheumatic valve disease); thisfalls to 1.6% with anticoagulation. Transoesopha-geal echocardiography (TOE) may exclude atrialappendage thrombus but cannot predict thedevelopment of a thrombus in the early stages post-cardioversion; anticoagulation is therefore alwaysrecommended post-cardioversion.

• Risk factors for stroke with non-valvular AF• Previous history of cerebrovascular

accident or transient ischaemic attack(risk 322.5)

• Diabetes (31.7)• Hypertension (31.6)• Heart failure

• Risk factors for recurrence of AF aftercardioversion• Long duration (.1–3 years)• Rheumatic mitral valve disease• Left atrium size .5.5 cm• Older age (.75 years)• Left ventricular impairment

The CHADS 2 score can be used for stratifyingthromboembolic risk in AF:

• 1 point is awarded for each of: congestiveheart failure, hypertension, age over 75,diabetes

• 2 points are awarded for systemic emboli• A score of 3 indicates a high risk of

thrombus formation and is a strongindication for anticoagulation

• Scores of 1 and 2 are intermediate values(anticoagulation is given at the discretion ofthe physician)

• The score has the virtue of simplicity but isquite conservative, probablyunderestimating the risk associated withprior stroke/transient ischaemic attack

1.5.4 Ventricular arrhythmias andchannelopathies

Ventricular tachycardia (monomorphic)

Ventricular tachycardia (VT) has a poor prognosiswhen left ventricular function is impaired. After theexclusion of reversible causes such patients may

Cardiology

27

need implantable defibrillators and anti-arrhythmictherapy.

• Ventricular rate is usually 120–260 beats/min• Patients should be DC cardioverted when there

is haemodynamic compromise; overdrivepacing may also terminate VT

• Amiodarone, sotalol, flecainide and lidocainemay be therapeutic adjuncts or prophylacticagents; magnesium may also be useful

Associations of ventricular tachycardia

• Myocardial ischaemia• Hypokalaemia or severe hyperkalaemia• Long QT syndrome (see below)• Digoxin toxicity (VT may arise from either

ventricle, especially with associatedhypokalaemia)

• Cardiomyopathies• Congenital abnormalities of the right

ventricular outflow tract (VT with LBBB andright axis deviation pattern)

Features favouring ventricular tachycardia in

broad-complex tachycardia

It is often difficult to distinguish VT from SVT withaberration (disordered ventricular propagation of asupraventricular impulse); VT remains the mostcommon cause of a broad-complex tachycardia,especially with a previous history of MI. The follow-ing ECG observations favour VT:

• Capture beats: intermittent SA node complexestransmitted to ventricle

• Fusion beats: combination QRS from SA nodeand VT focus meeting and fusing (causescannon waves)

• RBBB with left axis deviation• Very wide QRS .140 ms

• Altered QRS compared to sinus rhythm• V lead concordance with all QRS vectors,

positive or negative• Dissociated P waves: marching through the VT• History of ischaemic heart disease: very good

predictor• Variable S1• Heart rate ,170 beats/min with no effect of

carotid sinus massage

Note: none of the above has as high a positivepredictive value for VT diagnosis as a history ofstructural heart disease (especially MI).

Ventricular tachycardia (polymorphic) ^

torsades de pointes

Anti-arrhythmic agents (particularly class III) maypredispose to torsades as the arrhythmia is ofteninitiated during bradycardia. The VT is polymorphic(QRS complexes of different amplitudes twistaround the isoelectric line), with QT prolongationwhen the patient is in sinus rhythm.

• Intravenous magnesium and Kþ channelopeners may control the arrhythmia, whereasisoprenaline and temporary pacing may preventbradycardia and hence the predisposition to VT

• May be due to QT prolongation of any cause(see later)

Proarrhythmic channelopathies

Abnormally prolonged QT intervals may be familialor acquired, and are associated with syncope andsudden death, due to ventricular tachycardia (espe-cially torsades de pointes). Mortality in the un-treated symptomatic patient with a congenitalabnormality is high but some patients may reachthe age of 50–60 years despite repeated attacks.Causes and associations are shown below.


28

Proarrhythmic causes of abnormal

repolarisation (ST-T changes)

• Familial• Long QT syndromes 1–5• Brugada syndrome• Short QT syndrome• Arrhythmogenic right ventricular

dysplasia• Drugs

• Quinidine• Erythromycin• Amiodarone• Tricyclic antidepressants• Phenothiazines• Probucol• Non-sedating antihistamines

(eg terfenadine)• Ischaemic heart disease• Metabolic

• Hypocalcaemia• Hypothyroidism• Hypothermia• Hypokalaemia

• Rheumatic carditis

Long QT syndromes: The corrected QT is .540 ms(normal ¼ 380–460 ms). Ninety per cent are famil-ial, with chromosome 11 defects being common(Romano–Ward syndrome has autosomal dominantinheritance; Jervell–Lange-Nielsen syndrome isautosomal recessive and associated with congenitaldeafness). Arrhythmias may be reduced by a combi-nation of â-blockers and pacing.

Cardiac causes of electromechanical

dissociation

When faced with a cardiac arrest situation it isimportant to appreciate the list of causes of electro-mechanical dissociation (EMD):

• Hypoxia• Hypovolaemia• Hypokalaemia/hyperkalaemia• Hypothermia• Tension pneumothorax• Tamponade• Toxic/therapeutic disturbance• Thromboembolic/mechanical obstruction

1.5.5 Pacing and ablation procedures

Temporary pacing

The ECG will show LBBB morphology (unless thereis septal perforation, when it is RBBB). Pacing maybe ventricular (right ventricle apex) or AV (atrialappendage and right ventricle apex) for optimisedcardiac output.

Complications include:

• Crossing the tricuspid valve during insertion,which causes ventricular ectopics, as doesirritating the outflow tract

• Atrial or right ventricular perforation andpericardial effusion

• Pneumothorax: internal jugular route ispreferable to the subclavian one, as it minimisesthis risk and also allows control after inadvertentarterial punctures

Permanent pacing

More complex permanent pacing systems includerate-responsive models, which use movement sen-sors or physiological triggers (respiratory rate or QTinterval) to increase heart rates. Although moreexpensive they avoid causing pacemaker syndromeand they act more physiologically for optimal leftventricular function.

Cardiology

29

• Indications for temporary pacing• Asystole• Haemodynamically compromised

bradycardia• Prophylaxis of MI complicated by

second-degree or complete heart block• Prior to high-risk cardiac interventions

or pacemaker replacement• Prevention of some tachyarrhythmias

(eg torsades)• Overdrive termination of various

arrhythmias (eg atrial flutter, VT)• Indications for permanent pacing

• Chronic AV block• Sick sinus syndrome with symptoms

(including chronotropic incompetence– the inability to appropriately increasethe heart rate with activity)

• Post-AV nodal ablation for arrhythmias(elective or inadvertent)

• Neurocardiogenic syncope• HCM• Dilated cardiomyopathy (may pace

more than two chambers)• Long QT syndrome• Prevention of atrial fibrillation• Post-cardiac transplantation

Pacing in heart failure

There are several synonymous terms for pacing inpatients with cardiac failure. These include ‘cardiacresynchronisation therapy’, ‘biventricular pacing’and ‘multisite pacing’. In heart failure pacing isindicated when all of the following are present:

• NYHA III–IV heart failure• QRS duration .130 ms or other clear evidence

of dyssynchrony• Left ventricular ejection fraction ,35% with

dilated ventricle and patient on optimal medicaltherapy (diuretics, angiotensin-convertingenzyme (ACE) inhibitors and â-blockers)

The atria and right ventricle are paced in the usualfashion and in addition to this a pacing electrode isplaced in a tributary of the coronary sinus on the

lateral aspect of the left ventricle. The two ventriclesare paced simultaneously or near-simultaneouslywith a short AV delay. The aim is to optimise AVdelay and reduce inter- and intraventricular asyn-chrony. This therapy is known to reduce mortality,to improve exercise capacity, to improve quality oflife and to reduce hospital admissions.

Implantable cardioverter de¢brillators (ICD)

ICDs are devices that are able to detect life-threa-tening tachyarrhythmias and to terminate them byoverdrive pacing or a counter-shock. They are im-planted in a similar manner to permanent pace-makers. Current evidence supports their use in bothsecondary prevention of cardiac arrest and also astargeted primary prevention (eg for individuals withleft ventricular impairment and those with familialsyndromes such as arrhythmogenic right ventriculardysplasia, Brugada syndrome, long QT variants).

Radiofrequency ablation

Radiofrequency ablation is resistive, heat-mediated(658C) protein membrane disruption causing celllysis. Using cardiac catheterisation (with electrodesin right- or left-sided chambers) it interrupts electri-cal pathways in cardiac structures. Excellent resultsare obtained in the treatment of accessory pathwaysand atrial flutter, and with complete AV nodal abla-tion or AV node modification. Ventricular tachycar-dia is technically more difficult to treat (ventricularmyocardium is much thicker than atrial myocar-dium).

Isolation of the pulmonary veins by ablation therapyis now an established technique to treat atrial fibril-lation. Current cure rates are around 85%, but morethan one procedure is required in half the cases.Complete heart block and pericardial effusions arerare complications of radiofrequency ablation.

Indications to refer to an electrophysiologist

Indications for referral to an electrophysiologist aregiven in Table 1.5.


30

1.6 ISCHAEMIC HEART DISEASE

In 1990 coronary artery disease became the leadingworldwide cause of death, currently claiming 7.2million lives per year.

Risk factors for coronary artery disease

• Primary• Hypercholesterolaemia (LDL*)• Hypertension• Smoking

• Unclear• Low fibre intake• Hard water• High plasma fibrinogen levels• Raised Lp(a) levels• Raised factor VII levels

• Protective factors• Exercise• Moderate amounts of alcohol• Low cholesterol diet• Increased HDL:LDL**

• Secondary• Reduced HDL cholesterol• Obesity• Insulin-dependent diabetes mellitus• Non-insulin-dependent diabetes• Family history of coronary artery disease• Physical inactivity• Stress and personality type• Gout and hyperuricaemia• Race (Asians)• Low weight at 1 year of age• Male sex• Chronic renal failure• Increasing age• Low social class• Increased homocystine levels and

homocystinuria

*Low-density lipoprotein

**Ratio of high-density lipoprotein to LDL

Table 1.5. Indications for referral to an electrophysiologist

Condition When to refer Potential treatment

SVT More than one episode Radiofrequency ablation

Atrial flutter More than one episode Radiofrequency ablation

Atrial fibrillation Highly symptomatic, refractory toor intolerant of drug therapy

Radiofrequency ablation

Ventricular fibrillation Unless there is an obviousreversible cause, eg ST-segmentelevation MI (STEMI)

ICD

Ventricular tachycardia Unless obvious reversible cause Radiofrequency ablation or ICD

Ischaemic cardiomyopathy Ejection fraction ,30% onoptimal medical therapy

Primary prevention ICD

NYHA class III–IV heart failure, QRS.130 ms, ejection fraction ,35%

On optimal medical therapy Heart failure pacing

Cardiology

31

Smoking and its relationship to

cardiovascular disease

Smokers have an increased incidence of the follow-ing cardiovascular complications:

• Coronary artery disease• Malignant hypertension• Ischaemic stroke• Morbidity from peripheral vascular disease• Sudden death• Subarachnoid haemorrhage• Mortality due to aortic aneurysm• Thromboembolism in patients taking oral

contraceptives

Both active and passive smoking increase the risk ofcoronary atherosclerosis by a number of mechan-isms. These include:

• Increased platelet adhesion/aggregation andwhole-blood viscosity

• Increased heart rate; increased catecholaminesensitivity/release

• Increased carboxyhaemoglobin level and, as aresult, increased haematocrit

• Decreased HDL cholesterol and vascularcompliance

• Decreased threshold for ventricular fibrillation

1.6.1 Angina

Other than the usual forms of stable and unstableangina, those worthy of specific mention include:

• Decubitus: usually on lying down – due to anincrease in LVEDP or associated with dreaming,cold sheets, or coronary spasm during rapid eyemovement (REM) sleep

• Variant (Prinzmetal): unpredictable, at rest, withtransient ST elevation on ECG. Due to coronaryspasm, with or without underlyingarteriosclerotic lesions

• Syndrome X: this refers to a heterogeneousgroup of patients who have ST-segmentdepression on exercise testing butangiographically normal coronary arteries. Thepatients may have very-small-vessel disease and/or abnormal ventricular function. It is

commonly described in middle-aged femalesand oestrogen deficiency has been suggested tobe an aetiological factor

• Vincent angina: nothing to do with cardiology;infection of the pharyngeal and tonsillar space!

Causes of non-anginal chest pains

• Pericardial pain• Aortic dissection• Mediastinitis

• Associated with trauma, pneumothoraxor diving

• Pleural• Usually with breathlessness in pleurisy,

pneumonia, pneumothorax or a largeperipheral pulmonary embolus

• Musculoskeletal• Gastrointestinal

• Including oesophageal, gastric,gallbladder, pancreatic

• Hyperventilation/anxiety• Reproduction of sharp inframammary

pains on forced hyperventilation is areliable test

• Mitral valve prolapse• May be spontaneous, sharp, superficial,

short-lived pain

Symptomatic assessment of angina

The Canadian cardiovascular assessment of chestpain is useful for grading the severity of angina:

• Grade I: angina only on strenuous or prolongedexertion

• Grade II: angina climbing two flights of stairs• Grade III: angina walking one block on the

level (indication for intervention)• Grade IV: angina at rest (indication for urgent

intervention)

1.6.2 Myocardial infarction

Conservative estimates suggest there are 113 000myocardial infarctions per year in the UK withsignificant pre-hospital mortality, and 5%–6% in-hospital mortality and 6%–7% 30-day mortality for


32

those surviving to hospital admission. Overall 19%of UK deaths are directly attributable to coronarydisease.

Diagnosis ofMI

Acute, evolving or recent MIEither one of the following criteria satisfies the diag-nosis for an acute, evolving or recent MI:

• Typical rise and gradual fall (troponin) or morerapid rise and fall (CK-MB) of biochemicalmarkers of myocardial necrosis with at least oneof the following:• Ischaemic symptoms• Development of pathological Q waves on

the ECG• ECG changes indicative of ischaemia (ST-

segment elevation or depression)• Pathological finding of an acute MI (eg at post-

mortem)

Established MIAny one of the following criteria satisfies the diag-nosis of an established MI:

• Development of new pathological Q waves onserial ECGs. The patient may or may notremember previous symptoms. Biochemicalmarkers of myocardial necrosis may havenormalised, depending on the length of timethat has passed since the infarct developed

• Pathological finding of a healed or healing MI• Previous MI is also suggested when coronary

artery disease and a regional ventricular wallmotion abnormality are seen, or characteristicmyocardial scars are observed with MRI

Distinction between ST-segment elevation MI(STEMI) and non-STEMI (NSTEMI)An acute MI should be classified as STEMI whenthere is:

• ST-segment elevation (2 mm in two or morechest leads, or 1 mm in two or more limb leads)

• A chronic MI with Q-wave formation• Pathological or imaging evidence of a full-

thickness scar

Other MIs that do not meet these criteria should beclassified as NSTEMI.

Cardiac enzymes

The widespread use of troponin assays has bothsimplified and lowered the bar for the diagnosis ofMI. A number of markers of cardiac damage arenow available. Table 1.6 is a guide to the timing ofthe initial rise, peak and return to normality.

Troponin assays in patients with renal failure

The troponin level may be elevated simply becausea patient has renal failure. In patients with renalfailure who present with chest pain it is helpful toassess the troponin level at baseline as well as at12 h after the onset of symptoms, and sometimes atlater time points. In these circumstances only arising troponin level would be suggestive of ischae-mic myocardial damage.

Complications ofMI

Since the advent of thrombolysis, complication rateshave been reduced (eg halved for pericarditis, con-duction defects, ventricular thrombus, fever, Dress-ler syndrome). All complications may be seen withany type of infarction, but the following are themost common associations.

• Complications of anterior infarctions• Late VT/VF• Left ventricular aneurysm• Left ventricular thrombus and systemic

embolism (usually 1–3 weeks post-MI)*• Complete heart block (rare)• Ischaemic mitral regurgitation• Congestive cardiac failure• Cardiac rupture – usually at days 4–10

with EMD• VSD with septal rupture• Pericarditis and pericardial effusion

(Dressler syndrome with higherythrocyte sedimentation rate (ESR),fever, anaemia, pleural effusions andanti-cardiac muscle antibodies is seenoccasionally)

Cardiology

33

• Complications of inferior infarctions• Higher re-infarction rate• Inferior aneurysm – with mitral

regurgitation (rare)• Pulmonary embolism (rare)• Complete heart block and other degrees

of heart block• Papillary muscle dysfunction and mitral

regurgitation• Right ventricular infarcts need high

filling pressures (particularly if posteriorextension)

*Although warfarin provides no general benefit, it may

reduce the overall CVA rate (1.5%–3.6%) in those

patients with echocardiographically demonstrable mural

left ventricular thrombus after a large anterior MI, so

recommended for up to 6 months after the infarction

Heart block and pacing aftermyocardial

infarction

• Temporary pacing is indicated in anterior MIcomplicated by complete heart block. Thispresentation is associated with high mortalitydue to the extensive myocardial damage. Thedecision as whether to temporarily pace apatient with inferior infarction and completeheart block is primarily dictated by the patient’shaemodynamic status. Atropine andisoprenaline can also be tried. Narrow-complexescape rhythms are more stable. Anobservational period of 7 days post-MI isappropriate to allow the return of sinus rhythmbefore considering permanent pacing

• The right coronary artery is the dominant vessel(over left circumflex) in 85% of patients. As thisgives off branches to SA and AV nodes, heart

Table 1.6. Guide to the timing of changes in cardiac enzymes

Marker Initialrise

Peak Return tonormal

Notes

Creatine phosphokinase* 4–8 h 18 h 2–3 days CPK-MB is main cardiac isoenzyme

Myoglobin 1–4 h 6–7 h 24 h Low specificity from skeletal muscle damage

Troponin** 3–12 h 24 h 3–10 days Troponins I and T are the most sensitive andspecific markers of myocardial damageavailable

Lactate dehydrogenase(LDH)

10 h 24–48 h 14 days Cardiac muscle mainly contains LDH

* Creatine phosphokinase has three isoenzymes, of which the CPK-MB isoenzyme is most cardiac-specific,although numerous other organs possess the enzyme in small quantities. A CPK-MB of .2.5% of the total CPK hasbeen suggested as very specific for MI in the context of chest pain. This is inaccurate in situations of significantacute or chronic skeletal injury, where CPK levels will be high** Troponin interpretation is specific to the assay used and local guidelines should be consulted. A level greaterthan the 99th centile for the assay is regarded as positive. Assays may be read only, semi-quantitative orquantitative. Positives occur in all conditions where myocardial damage occurs, including pulmonary embolus,myocarditis, extreme bradycardia or tachycardia, sepsis, renal impairment and uncontrolled diabetes mellitus


34

block might be observed if a dominant rightcoronary artery is occluded

1.6.3 Medical therapy for myocardialinfarction

Thrombolysis is beneficial up to 6 h after pain onsetbut may be given for up to 12 hours in the contextof continuing pain or deteriorating condition. Reca-nalisation occurs in 70% of patients after thrombo-lysis (compared with a 15% recanalisation ratewithout thrombolysis) and results in a higher, earliercreatine phosphokinase (CPK) rise (but a lower totalCPK release). Reperfusion arrhythmias are commonwithin the first 2 hours after thrombolysis.

Primary angioplasty is superior to thrombolysis foracute MI; the same ECG criteria apply to caseselection.

Tissue plasminogen activator and similar recombi-nant agents are accompanied by a prothromboticphase lasting about 48 hours and this period shouldbe covered with heparin.

Contraindications to thrombolysis

Although there are numerous relative contraindica-tions where the risk/benefit considerations are indi-vidual to the patient, there are several absolutecontraindications to thrombolysis.

Contraindications to thrombolysis

• Absolute contraindications• Active internal bleeding or

uncontrollable external bleeding• Suspected aortic dissection• Recent head trauma (,2 weeks)• Intracranial neoplasms• History of proved haemorrhagic stroke

or cerebral infarction ,2 months earlier• Uncontrolled high BP (.200/120

mmHg)• Pregnancy

• Relative contraindications• Traumatic prolonged cardiopulmonary

resuscitation• Bleeding disorders• Recent surgery• Probable intracardiac thrombus (eg AF

with mitral stenosis)• Active diabetic haemorrhagic

retinopathy• Anticoagulation or INR .1.8

Groups particularly benefiting from thrombolysis(determined by the GUSTO, ISIS 2 and ISIS 3 trials)include:

• Those with large anterior infarction• Those with pronounced ST elevation• Elderly (.75 years)• Those with poor left ventricular function or

LBBB, or systolic BP ,100 mmHg• Those who have early administration: within 1 h

of pain onset

Posterior infarction (a tall R wave in V1 with STdepression in leads V1–V3): no clear benefit ofthrombolysis has been shown as few such patientshave been enrolled into major trials (ECG interpreta-tion is often difficult when the presentation is notwith inferior infarct). However, the general consen-sus would still be to give thrombolysis. Sixty percent of posterior MIs are due to right coronary arterydisease.

NSTEMI: have not been shown to benefit fromthrombolysis. They have a low in-patient but high(65%) untreated 1-year mortality (compared to 34%for STEMI infarcts) and they should be investigatedearly and aggressively.

There is now a good evidence base for a range ofpharmacological treatments in patients presentingwith acute coronary syndromes (See Table 1.7).These are aimed at dispersing clot (aspirin, clopido-grel, heparin), preventing arrhythmias (â-blockers),stabilising plaque (statins) and preventing adverseremodelling.

Cardiology

35

Table 1.7. Summary of clinical trials in patients with acute MI*

Agents used for acute MI Mortality intreated group (%)

Mortality incontrol subjects(%)

Number treatedto save 1 life

Trials involved

Aspirin 9.4 (at 5 weeks) 11.8 42 ISIS 2

Clopidogrel 11.4 9.3 Compositeendpoint

CURE

Thrombolytics 10.7† (at 21 days) 13.0† 43† GISSI 1†, ISIS 2,TIMI II, GUSTO

â-Blockers 3.9 (at 7 days) 4.6 143 ISIS 1

ACE inhibitors 35.2† (after 39-month meanfollow-up)

39.7† 22† SAVE, SOLVD†, AIRE

Lipid-lowering therapy(patients with averagecholesterol)

10.2 (after 5 years) 13.2 33 CARE (note endpointsincluded second non-fatal MI and cardiacdeaths)

Heparin with aspirin andany form of thrombolysis

8.6 9.1 200 Meta-analysis of68 000 patients

Magnesium: contradictory data but no mortality reduction LIMIT 1, 2, ISIS 4

Nitrates: no clear benefit ISIS 4, GISSI 3

Warfarin: no proved benefit above aspirin after thrombolysis

* See also Appendix II: Summary of further trials in cardiology† Data from that particular trial


36

1.6.4 Coronary artery interventionalprocedures

Percutaneous coronary intervention (PCI)

After coronary angioplasty the recurrence or re-stenosis rate is 30% within 3 months and 40%–60% for total occlusions that are successfullydilated as treatment of acute MI. These figures havebeen greatly reduced, first by bare metal stents andthen further by drug-eluting stents. Drug-elutingstents are covered by an antimitotic agent to preventsmooth muscle/fibrous tissue proliferation. Unfortu-nately, they also inhibit endothelialisation so in-creasing the risk of thrombosis and so dualantiplatelet therapy (aspirin and clopidogrel) is man-datory for 12 months after the intervention andlifelong single antiplatelet therapy is required there-after.

• Lesions particularly amenable to PCI includethose that are discrete, proximal, non-calcified,unoccluded, that are away from side branchesand that occur in patients with a short history ofangina. While there is a small acute occlusionrate, these can usually be managed successfullywith intra-coronary stenting, such that the needfor emergency CABG has fallen to under 1%

• More challenging lesions include those withingrafts, at bifurcations, calcified or long lesionsand those within small vessels. Diabetics havepoorer outcomes compared with non-diabetics

• Almost any lesion can be stented including leftmain stem disease, three-vessel disease andeven chronic total occlusions but carefulevaluation and discussion with the patient arenecessary, as in many situations bypass graftinghas a better evidence base

Coronary artery bypass grafting (CABG)

CABG has clear benefits in specific groups of pa-tients with chronic coronary artery disease (whencompared with medical therapy alone). Analysis haspreviously been limited because randomised trialsincluded small numbers and were performed sev-eral decades ago; patients studied were usuallymales aged ,65 years. The population now receiv-ing CABG has changed, but so has medical therapy.

• Prognostic benefits are shown for symptomatic,significant left main stem disease (Veterans’Study), symptomatic proximal three-vesseldisease and in two-vessel disease whichincludes the proximal left anterior descendingartery (CASS data)

• Patients with moderately impaired leftventricular function show greater benefit, butthose with poor left ventricular function havegreater operative mortality. Overall mortality is,2%, rising to between 5% and 10% for asecond procedure. Eighty per cent of patientsgain symptom relief

• Peri-operative graft occlusion is around 10% forvein grafts, which otherwise last 8–10 years.Arterial grafts (internal mammary, free radial,gastro-epiploic) have a higher initial patencyrate but long-term outcomes are disappointingwith the exception of internal mammary grafts,which are clearly superior to vein grafts

• A ‘Dressler-like’ syndrome may occur up to6 months post-surgery

• Minimally invasive CABG involves theredirection of internal mammary arteries tocoronary vessels without the need for cardiacbypass and full sternotomy incisions (oftentermed ‘off pump’ coronary revascularisation).Recovery times following this procedure areshorter than for conventional surgery but theprocedures are technically more challenging

Post-MI rehabilitation

After MI patients are kept in hospital for 5 days,should take 2 months off work and have 1 month’sabstinence from sexual intercourse and driving (seefollowing text). Cardiac rehabilitation is particularlyimportant for patient confidence. Depression occursin 30% of patients. Patients who are fully revascu-larised or invasively investigated and found to haveno ongoing ischaemic focus may be dischargedafter 3 days and be rehabilitated more rapidly.

Fitness to drive

The DVLA provides extensive guidelines for coron-ary disease and interventions. Their website(www.dvla.gov.uk) should be consulted, especially

Cardiology

37

with regard to class 2 licences (for vehicles over3500 kg, minibuses and buses) but the essentialpoints are given in Table 1.8.

1.7 OTHER MYOCARDIAL DISEASES

1.7.1 Cardiac failure

Cardiac failure can be defined as the pumpingaction of the heart being insufficient to meet thecirculatory demands of the body (in the absence ofmechanical obstructions). A broad echocardio-graphic definition is of an ejection fraction (EF),40% (as in the SAVE trial, which enrolled patientsfor ACE inhibitors post-MI). Overall 5-year survivalis 65% with EF ,40%, compared to 95% in thosewith EF .50%.

The most common single cause of cardiac failure inthe Western world is ischaemic heart disease (IHD).

• Hypertension is also a very frequent cause –either acting alone or in combination with IHD

• Diastolic heart failure is increasingly recognisedalthough difficult to diagnose as an isolatedcondition. It describes impaired ventricularfilling that elevates pulmonary and/or systemicvenous pressure with activation of theneurohormonal system as seen in systolic heartfailure

• All patients with systolic heart failure have adegree of diastolic dysfunction – some believethat isolated diastolic dysfunction may be anearly step prior to development of systolic heartfailure

EF is only a guide to cardiac function, which alsodepends on other factors including pre-load, after-

Table 1.8. Fitness to drive

Condition Driving restriction Notes

Unexplained syncope 6 months from lastepisode or until effectivetreatment is given

Clear vasovagal events that occur onlywhen the patient is erect do not precludedriving

Cardiac catheter procedure (includingangiography, percutaneous coronaryintervention, electrophysiologicalstudies/ablation)

1 week Should be able to perform emergency stopunhindered

Myocardial infarction 1 month

Permanent pacemaker 1 month Only 1 week if the patient has never beensyncopal

Prophylactic ICD 1 month No clinical arrhythmia or syncope

Secondary prevention ICD 6 months DVLA must be informed

ICD shock therapy 6 months Unless an inappropriate shock ispreventable by reprogramming orintervention, eg a change in the detectionor therapy programming to avoid shocksfor sinus tachycardia or atrial arrhythmias


38

Documents

MRCP Revision Notes