S P E A K E R : D R O M A R K A M A L

PERIOPERATIVE MANAGEMENT OF

PATIENTS WITH IHD & PERIOPERATIVE MI

IHD

• Patients with IHD can present with chronic stable

angina or with acute coronary syndrome.

• Acute coronary syndrome includes STEMI and NSTEMI/

Unstable angina

DEFINITION

• Myocardial ischaemia is a dual state composed of

inadequate myocardial oxygenation and accumulation of

anaerobic metabolites and occurs when myocardial

oxygen demand exceeds the supply.

• Myocardial infarction is defined as the death of

myocardial myocytes due to prolonged ischaemia.

ANGINA PECTORIS

• An imbalance between CBF and myocardial oxygen

consumption can precipitate ischaemia manifesting as

angina.

• Develops due to partial occlusion or chronic narrowing of

a segment of coronary artery.

• Atherosclerosis is most common cause of impaired CBF.

ANGINA PECTORIS CONT..

• When imbalance between myocardial oxygen supply-

demand becomes extreme, it results in CHF,

Dysrhythmias and myocardial infarction.

• Chronic stable angina refers to chest pain or discomfort

that does not change appreciably in frequency or

severity over 2 months or longer.

ACUTE CORONARY SYNDROME

ST Elevation myocardial infarction

Pathophysiology

Plaque rupture : STEMI occurs due to decrease in CBF

due to formation of acute thrombus at a site where an

atherosclerotic plaque ruptures, fissures or ulcerates.

Typically vulnerable plaques more prone to rupture.

Diagnosis

1. Chest pain

2. Serial ECG changes indicative of MI

3. Increase and decrease of serum cardiac enzymes

UNSTABLE ANGINA/NSTEMI

• UA is defined as angina at rest, angina of new onset, or

increase in severity or frequency of previously stable

angina.

• Due to imbalance between myocardial oxygen supply

and demand.

• Typically rupture of atherosclerotic coronary plaque

leads to thrombosis, inflammation and vasoconstiction.

COMPLICATIONS

1. Dysrhythmias – VF,VT, AF and Heart block.

2. Pericarditis – Dressler s Syndrome

3. Mitral regurgitation

4. Ventricular Septal rupture

5. CHF and Septic shock

6. Myocardial rupture

7. Right ventricular infarction

8. Cerebrovascular accident

RISK FACTORS

i.Life style and smoking

ii.Recent myocardial infarction

iii.Congestive cardiac failure

iv.Peripheral vascular disease

v.Angina pectoris

vi.Diabetes mellitus

vii.Hypertension

viii. Hypercholesterolemia

ix. Dysrrhythmias

x. Age and Sex

xi. Renal dysfunction

xii.Obesity

1. PREOPERATIVE EVALUATION

A) History

1. History of cardiac symptoms

• Chest pain, Palpitations, Syncope, Breathlessness, Orthopnea, Paroxysmal Nocturnal Dyspnea

2. Exercise tolerance :- It depicts the cardiac reserve.

• Excellent -history of participation in sports like swimming, football, tennis, basket-ball, skating etc.

• Adequate-patient able to climb stairs, run a short distance.

• Poor- able to do leisure activities only e.g. slow daily activities in the house only.

3. Angina pectoris:-It is the symptomatic manifestation of myocardial ischaemia characterized by typical substernalpain which is evoked by physical exertion and relieved by rest or sublingual nitroglycerine.

4. Myocardial infarction:-

According to Tarhan et al –

• Incidence of perioperative re-infarction is 37% if the time elapsed is less than 3 months,

• 16% when time elapsed is 4-6 months and

• 5% when time elapsed is more than 6 months.

• This is the basis for recommendation to wait for 6 months after MI for elective major surgery

5. Co-existing noncardiac diseases

i. Peripheral vascular disease

ii. Cerebro vascular disease

iii. COPD in patients with history of cigarette smoking

iv. Renal dysfunction may be associated with chronic

hypertension

v. Diabetes- May be the cause of silent MI

vi. Anaemia, polycythemia, thrombocytosis when

present will need careful management

6. Current medications-

Awareness about the medications that patient is taking is

important during anaesthesia.

• All cardiac medications like beta blockers, calcium

channel blockers, nitrates should be continued until the

morning of surgery.

• Patient may be on anticoagulants which should be

stopped 5-7 days prior to surgery.

7. Congestive heart failure, Dysrrhythmias

EXAMINATION

• Assessment of vital signs like blood pressure, pulse rate

and rhythm, jugular venous, pulse, oedema, pallor,

cyanosis, clubbing , jaundice, lymphadenopathy.

• In systemic examination, cardiovascular system should

be examined for heart sounds & any murmur.

• Further evaluation is needed as per the findings.

• Respiratory system also needs to be assessed in details

LABORATORY INVESTIGATIONS

Routine investigations

• Hb – Anaemia

• CBC – Leucocytosis, Thrombocytopenia

• Renal function tests

• Coagulation profile

• Chest X ray

• ECG

Specific investigations like

A) Noninvasive :

• Echocardiography - to know ejection fraction, any valvular

lesion , wall motion abnormalities, LV function and pressure

gradients,

• Holter monitoring, Treadmill test, thallium scintigraphy

to detect myocardium at risk,

• Radionuclide ventriculography,

• Dobutamine stress test(DST) for evaluating inducible

ischemia in patients who have poor functional capacity,

B) Coronary angiography in patients where DST is positive.

ANAESTHETIC MANAGEMENT

Anaesthesia goals

i. Stable haemodynamics

ii. Prevent MI by optimizing myocardial oxygen supply and

reducing oxygen demand

iii.Monitor for ischaemia

iv. Treat ischemia or infarction if it develops

v. Normothermia

vi. Avoidance of significant anaemia

• Management depends upon the type of surgery whether

emergency or elective.

• For emergency surgery, proceed for the surgery with

medical management of cardiac ailment.

• For elective surgery perioperative management

depends upon various clinical risk factors and surgery

specific risk factors.

RISK STRATIFICATION

SURGERY SPECIFIC RISK FACTORS

1. High risk surgeries- emergent major operations particularly

in the elderly, aortic and other major vascular surgery,

anticipated prolonged surgical procedures associated with large

fluid shifts or anticipated blood loss --- cardiac risk > 5%.

2. Intermediate risk surgeries- carotid endarterectomy,

head and neck surgery, intraperitoneal and intrathoracic

surgery, prostate surgery -- cardiac risk 1- 5%.

3. Low risk procedures:- endoscopic procedures, superficial

procedures, cataract surgeries, breast surgery

Cardiac risk < 1%.

CARDIAC RISK INDICES

LEE REVISED CARDIAC INDEX SCORE

1. High risk surgery

2. H/O IHD

3. H/O Compensated or Prior heart failure

4. H/O Cerebrovascular disease

5. Diabetes Mellitus – Insulin treatment

6. Renal Insufficiency – Creatinine > 2mg/dl

ASSESSMENT OF FUNCTIONAL CAPACITY

PREOPERATIVE MANAGEMENT

• Main reason for risk stratification is to identify patients at

increases risk. So as to manage them with

pharmacologic and other perioperative interventions that

can ameliorate perioperative cardiac events.

1. Optimisation of medical management

2. Revascularization by PCI (BMS, DES)

3. Revascularization by surgery( CABG)

TREATMENT

1. Identification and treatment of diseases that can

precipitate or worsen ischaemia.

2. Reduction of risk factors for coronary artery disease.

3. Lifestyle modification

4. Pharmacological management of angina

5. Revascularization by coronary artery bypass grafting

(CABG)or percutaneous coronary intervention (PCI) with

or without placement of intercoronary stents

Reduction of risk factors and lifestyle modification

• Cessation of smoking

• Maintainence of ideal body weight- low fat , low

cholestrol diet

• Regular exercise

• Treatment of hypertension .

• Lowering of LDL cholesterol by drugs or diet

MEDICAL MANAGEMENT

1. Antiplatelet drugs

2. B Blockers

3. CCB

4. Nitrates

5. Ace inhibitors

1. Antiplatelet drugs – Low dose aspirin (75-300 mg/day)

decreases the risk of cardiac events in patients with stable or

unstable angina. Ticlopidine, clopidogrel, Gp 11b/111a

inhibition(Abciximab, Eptifibatide, Tirofiban) are commonly used

that prevent platelet aggregation.

2. β-Adrenergic Blocking Agents : These drugs decrease

myocardial oxygen demand by reducing heart rate and

contractility. Optimal blockade results in a resting heart rate

between 50 and 60 beats/min. Patients on long-standing β-

blocker therapy should have these agents continued

perioperatively.

3. Calcium Channel Blockers :

• The effectiveness of CCB is due to their ability to decrease vascular smoothy muscle tone, dilate coronary arteries, decrease myocardial contractility and oxygen consumption, and decrease arterial pressure

• CCB reduce myocardial oxygen demand by decreasing cardiac afterload and augment oxygen supply by increasing blood flow (coronary vasodilatation).

• Verapamil and diltiazem also reduce demand by slowing the heart rate.

• CCB are uniquely effective in deceasing severity and frequency of angina pectoris due to coronary artery spasm (Printzmetals or Variant angina)

4. Nitrates

• Nitrates relax all vascular smooth muscle, Venodilatation

greater than dillatation of arteries

• They reduce myocardial oxygen demand by decreasing

venous and arteriolar tone and reducing the effective

circulating blood volume (cardiac preload), thus reducing wall

tension afterload.

• Nitrate-induced coronary vasodilatation preferentially

increases subendocardial blood flow in ischemic areas.

• Nitrates can be used for both the treatment of acute ischemia

and prophylaxis against frequent anginal episodes.

REVASCULARISATION

• Revascularisation by CABG or Percutaneous Coronary

Intervention(PCI) with or without placement of intra

coronary stents is indicated when optimal medical

therapy fails to control angina pectoris.

• It is indicated for specific anatomic lesions like left main

stenosis > 70%, Combination of two or three-vessel

disease with LAD stenosis > 70% , Impaired left

venticular contractility (Ejection fraction <50%)

RECOMMENDED TIME INTERVALS TO WAIT FOR

ELECTIVE NON CARDIAC SURGERY

Procedure Time to wait

Balloon Angioplasty 2-4 wks

Bare metal stent 4-6 wks

CABG 6 wks

Drug eluting stent 12 months

•

PREANAESTHETIC CONSIDERATIONS

• Preoperative visit to the patient is very important.

• A good rapport should be made with the patient and written consent obtained.

• Patient should be explained about the risk of surgery and anaesthesia.

• It is important to continue the medications till the day of surgery like beta blockers,calcium channel blocker ,digitalis.

• Potassium level should be normal as hypokalemia can cause digitalis toxicity.

• Anticoagulants should be stopped.

PREMEDICATION

• Significance of premedication in allaying anxiety in

cardiac patients is of paramount importance.

• This is to prevent increase in B.P. and HR which can

disturb the myocardial oxygen supply and demand and

can induce ischaemia.

• Tab Diazepam 5mg or Alprazolam 0.5mg night before

surgery.

• Tab Ranitidine 150 mg night before surgery and Inj

Ranitidine 50 mg IV 1 hr before surgery

INTRAOPERATIVE MANAGEMENTMONITORING

• Incidence of ischaemia in the intraoperative period is low

as compared with pre and postoperative period.

i. ECG is the most commonly used monitoring tool .

Monitoring three ECG leads ( II,V4,V5 or V3,V4,V5 )

improves recognition of ischaemia. The ST segment

trending system also helps in the detection of ischaemia

ii. Blood pressure

iii. Pulse oximetry

iv. Capnography

v. Temperature monitoring

vi. Urine output monitoring

vii. Central venous pressure

viii. Pulmonary artery pressure and cardiac output – can

be measured with as required. In a haemodynamically

unstable patient, the requirement of volume or inotropes

can be judiciously calculated and response monitored

closely

ix. TEE is the most sensitive monitor for ischaemia.

CHOICE OF ANAESTHETICS

1. Intravenous anaesthetics

Thiopentone—It reduces myocardial contractility, preload and blood pressure.

• There is slight increase in heart rate and should be administered slowly and with caution.

Propofol-— It reduces arterial blood pressure and heart rate significantly. There is dose dependent reduction in myocardial contractility.

• It can be used in with good ventricular function but is not good induction agent for patients with CAD.

Ketamine-—It is not good in IHD and valvular heart disease patients.

• It is however a useful agent in situations like cardiac tamponade and cyanotic heart disease.

• Midazolam—It produces decrease in mean arterial

pressure and increase in heart rate. It provides excellent

amnesia and is widely used for patient with CAD

• Etomidate—It causes minimum haemodynamic changes.

It is excellent for induction in patients with poor cardiac

reserve.

2. Narcotics —

• Morphine is the preferred drug for its relative cardiac

stability and very good analgesic effect.

• It produces arterial and venous dilatation, resulting in

reduction of afterload and preload.

• Newer narcotic analgesic agents like fentanyl, alfentanyl

and sufentanil also provide adequate cardiac stability

and pain relief.

3. Inhalational agents- Isoflurane is recommended in

patients with good myocardial contractility.

• Halothane has the disadvantage of myocardial

depression and potential of dysrrhythmias.

4.Nitrous oxide—It provides stable haemodynamics in

cardiac patients.

5. Muscle relaxants-

• Muscle relaxants with minimal or no effect on heart rate

and systemic blood pressure (Vecuronium ,Rocuronium,

Cisatracurium) are attractive choices for patients with

IHD.

• Histamine release and resultant decrease in blood

pressure caused by atracurium are less desirable.

• Vecuronium produces minimum haemodynamic

alterations and is suitable for use in cardiac patients.

6. Glycopyrrolate— Reversal with anticholinesterase

anticholinergic drug can be safely accomplished in

patients with IHD.

• It is preferred over atropine since it produces less

tachycardia

REGIONAL ANAESTHESIA

Advantages :

• Excellent pain control, Decreased DVT, Avoids stress

response to intubation.

Demerits :

• Hypotension from uncontrolled sympathetic blockade and

need for volume loading can result in ischemia.

• Larger doses of local anaesthetic can cause myocardial

toxicity and myocardial depression.

• Use of epinephrine with local anaesthetic is not

recommended.

MANAGING INTRAOPERATIVE COMPLICATIONS

1. Intraoperative ischaemia

A) If patient is haemodynamically stable —

• Beta blockers ( I/V metoprolol upto 15mg)

• I/VNitroglycerine

• Heparin after consultation with surgeon

B) If patient is haemodynamically unstable –

• Supportwith inotropes

• Use of intraoperative ballon pump may be necessary

• Urgent consultation with cardiologist to plan for earliest possible cardiac catheterization

2. Other complications like dysrrhythmias, pacemaker dysfunction should be managed accordingly

POST OPERATIVE MANAGEMENT

Goals are same as intraoperative

i. Prevent ischaemia ii. Monitor for MI iii. Treatment for MI

• Most cardiac events occur within first 48 hours and

delayed cardiac events occur within first 30 days as a

result of secondary stress.

• Post operative stress of extubation, pain, sepsis,

haemorrhage, anaemia, respiratory problems can

increase the demand on the heart and should be

minimized and treated.

PERIOPERATIVE MI

• Ischemic cardiac morbidity is the most common cause of

perioperative death around 10-40%

• (PMI) is most important predictor of short- and long-

term morbidity and mortality associated with non-cardiac

surgery.

• Prevention of a PMI is a prerequisite for the

improvement in overall postoperative outcome.

• Perioperative myocardial ischemias (PMIs) are likely to

occur in patients undergoing urgent or emergent surgery.

• MIs in the modern era are more likely to occur in the first

72 hours following surgery.

WHY MI OCCURS IN THE FIRST FEW

POST OP DAYS?

• Loss of intravascular blood volume

• Tachycardia from inadequate pain control

• Poor breathing efforts by the patient due to surgical site

pain

• Surgery stimulates inflammatory response leading to

hypercoagulability which increases the thrombosis risk

PATHOPHYSIOLOGY

FACTORS AFFECTING MYOCARDIAL

OXYGEN SUPPLY–DEMAND BALANCE

Decreased oxygen supply Increased oxygen demand

Decreased coronary blood flow Tachycardia

Tachycardia(low diastolic perfusion

time)

Increased wall tension

Hypotension Increased preload

Anaemia, Hypoxemia, Reduced

oxygen release from Hb

Increased afterload

Hypocapnia(Coronary VC) Increased myocardial contractility

Coronary artery spasm

Decreased oxygen content

DIAGNOSIS

According to the definition of WHO , at least 2 of the 3

criteria must be fulfilled to diagnose MI:

typical ischemic chest pain

Increased serum concentration of creatine kinase (CK-

MB)

Typical ECG finding including development of

pathological Q waves.

AHA GUIDELINES

• Increase in cardiac enzyme markers (trop I and Trop T).

• Symptoms of MI

• New Q waves

• ST segment elevation or depression

MONITORING

• ECG monitoring standard.

• ST segment depression is a more common indicator of myocardial ischemia in surgery patients than is ST segment elevation. ST segment depression occurs in 20 to 50% of patients undergoing surgery.

• A multilead system to detect ischemia (V3, V4, V5 for maximal detection).

• , leads V3 to V4 have a higher incidence and a greater degree of maximal myocardial ischemia than does lead V5.

• automated ST segment monitors promise to increase the detection .

• Most (>80%) PMIs occur early after surgery, are asymptomatic, of the non-Q-wave type (60–100%),

• most commonly preceded by ST-segment depression rather than ST-segment elevation.

• Long- duration (single duration >20–30 min or cumulative duration >1–2 h) rather than merely the presence of postoperative ST-segment depression, seems to be the important factor associated with adverse cardiac outcome.

• Patients manifest MI in the immediate postoperative

period, with its associated pain, adrenergic stress,

hypothermia, hypercoagulability, anemia, shivering, and

sleep deprivation.

• clinical practice is to obtain a 12-lead ECG in the first 24

hours following surgery in high-risk patients, and then

perhaps daily for the next 2 to 3 days

• capillary wedge pressure (PCWP) monitoring in patients

undergoing surgery has low sensitivity and specificity in

detecting ischemia.

• PCWP as a monitor for myocardial ischemia is not

routinely used, but the pulmonary artery catheter

provides useful information about a patient's

intravascular volume status, myocardial performance,

and organ perfusion

• TEE has also been proposed as a monitor for

intraoperative myocardial ischemia. .

• regional wall motion abnormalities were more sensitive

than ST segment change on the ECG in detecting

intraoperative ischemia .

• However, it has been concluded that ischemia

monitoring with TEE during noncardiac surgery

appeared to have little incremental clinical value over

preoperative clinical data and Holter monitoring in

predicting perioperative ischemic outcomes

MANAGEMENT

Two principal strategies have been used

1. Preoperative coronary revascularization

2. Pharmacological treatment

TREATMENT OF PERIOPERATIVE

MYOCARDIAL ISCHAEMIA

1. Prevention of MI :

• Prevent tachycardia.

• Maintenance of adequate depth of anaesthesia and judicious use

of ultra short acting B blockers.

• Adequate measures to attenuate pressor responses to laryngoscopy

and endotracheal intubation.

• If haemodynamic aberrations are associated with myocardial

ischaemia, they may precede and be the cause of ischaemia .

2. Treatment of MI without accompanying

haemodynamic alterations:

In patients with haemodynamic alterations,

nitroglycerine can be useful as it decreases preload and

wall tension, dilates epicardial coronary arteries, and

increases subendocardial blood flow.

3. Treatment of MI accompanied

by tachycardia and hypertension:

• disturbs the myocardial oxygen demand and supply

balance.

• After ensuring adequate ventilation, oxygenation and

anaesthetic depth, B blockers may be administered in a

titrated manner provided there is no evidence of CHF or

bronchospasm.

4. Treatment of MI accompanied by tachycardia and

hypotension:

• MI occurs due to drastically reduced myocardial oxygen

supply.

• Prompt volume replacement to restore coronary

perfusion pressure and slow the rate.

5. Severe resistant MI :

• One which is resistant to all antianginal drugs.

• Here intraaortic balloon pump (IABP) can be useful

as it acutely decreases myocardial oxygen requirements

and may increases the oxygen supply.

TREATMENT OF PERIOPERATIVE

MYOCARDIAL INFARCTION

• Ensure adequate depth of anaesthesia, oxygenation (100%) and ventilation

• Once the diagnosis of acute MI is made, it is important to monitor the patient carefully.

• 100% oxygen should be administered and volatile

agent discontinued.

• Aspirin 325 mg is administered orally (through ryle’s tube if unable to take orally) and is continued thereafter.

• Prompt and aggressive treatment of changes in HR and/or BP is indicated.

• Tachycardia is treated with IV B blockers like Esmolol 50-100 μg IV or propranolol 0.5-1 mg/kg IV, until heart rate is < 90/min.

• Nitroglycerine is the drug of choice in the presence of normal to modestly elevated systemic BP started at1-2 μg/kg/min to maintain SBP 90 to 110

• Morphine is a venodilator that reduces ventricular

preload and oxygen requirements and also acts as an analgesic .

• Hypotension should be rapidly treated in order to

restore coronary perfusion pressure (CPP). Moderate hypotension often responds to volume expansion with 300- 500ml of crystalloid.

• If severe hypotension (60-80mmHg systolic) persists despite volume expansion, vasoactive or inotropic drugs may be given to elevate CPP above critical value.

POST OPERATIVE CARE

• Continuous ECG monitoring for post op MI

• Provision of supplemental oxygen

• Adequate post operative pain relief

• Continuation or institution of beta blockade

• Temperature control – Post operative shivering.

• Maintenance of hemodynamics with IV fluids

• DVT prophylaxis

REFERENCES

• Anaesthetic Considerations in Cardiac Patients Undergoing Non

Cardiac Surgery. Tej K. Kaul, Geeta Tayal. IJA 2007; 51 (4) : 280-

286

• Perioperative Myocardial Infarction. Circulation. 2009;119:2936-

2944. American Heart Association

• Perioperative Myocardial Ischaemia and Infarction-a Review.

Satinder Gombar,Ashish Kumar Khanna, Kanti Kumar Gombar. IJA

2007; 51 (4) : 287-302

• Textbooks Stoeltings, Millers, Barash

THANK YOU