Physiology of Cardiac Defects (Heart Sounds, murmurs and valvular problems),

Dr. shafali singh

Learning objectives

• Overview of the pressure volume loops• Describe the timing and causes of the four

heart sounds.• Describe the expected auscultation sounds

that define mitral stenosis, mitral insufficiency, aortic stenosis, and aortic insufficiency. Explain how these pathologic changes would affect cardiac mechanics and pressure.

Pressure changes

Pressure changes

Ventricles Increase in peak ventricular pressure >120;means aortic valvular pathology

AtriaIncrease in pressure >15mmHg; means mitral valve pathology

Pressure gradient

between peak ventri cular and peak

aortic presuure

Obstruction of aortic valve; AS

No pressure gradient

between peak ventricular and

peak atrial pressure

Aortic insufficiency

When pressure increase ?

During Ventricular

diastole ;MS

During ventricular systole; MI

• Aortic Regurgitation• Aortic Stenosis• Mitral Regurgitation• Mitral Stenosis

• Aortic Stenosis• Aortic Regurgitation• Mitral Stenosis • Mitral Regurgitation• Normal Findings

Two audible heart sounds: They are termed the first (S1) and second (S2).

They sound like “lub dup”.

The first is low pitched and the second is high.

Sounds come from turbulent flow around the valve cusps and vibration of the heart structures

The first heart sound is complex

1. Regurgitant flow across the closing mitral valve.

2. Abrupt closure of mitral and tricuspid valves..

3. Rapid acceleration of blood out of the ventricles

FIRST HEART SOUND-S1

• Character – Low pitch, Booming, longer

Auscultatatory areas – Apical area(Mitral) & Tricuspid area

• Closure of AV valves – LUB• Vibrations of Chordae tendinae• Vascular – Turbulence of blood

flow• Muscular – vibrations in

ventricular muscle as it starts to contract

Coincides with • Isometric contraction

phase• Peak of R wave of ECG• Phlebogram – Onset of C

wave

Second heart sound occurs at the end of systole and is due to closure of the two semilunar valves.

The second heart sound is normally split because both valves do not always close simultaneously.

SECOND HEART SOUND-S2

• Higher pitch, Snapping, Shorter

Auscultation area– Aortic and Pulmonary area

• Closure of Semi Lunar Valves - DUP

Coincides with• Onset of ventricular

diastole• Preceded/coincides or

follows T wave• Phlebogram – Ascending

limb of v wave

•2 components•Aortic (A2) & Pulmonary (P2)•Normally P2 softer than A2

EKG EVENT VALVULAR EVENT

SOUND

P wave Atrial depolarisation

Mitral valve open

(ventricle is filling)

S4(S3 prior to P

wave)

PR interval AV Node conduction

- -

QRS Ventricular depolarization

Mitral valve close

S1

QT interval Ejection phase Aortic valve is open

No sound

T wave Ventricular repolarization

Aortic valve closure

S2

Things that delay ejection such as aortic stenosis.

Things that weaken the left ventricle’s muscle such as left ventricular failure.

Two more sub-audible heart sounds are present, the third (S3) and fourth (S4) heart sounds.

S3 results from rapid filling of the ventricle during diastole.

THIRD HEART SOUND-S3

• Physiologic Atrial heart sound

• Low intensity

• Low pitched Can be recorded

• Due to Rapid ventricular filling• Vibrations of ventricular wall

• Frequently heard in children

• Thin walled chest, exercise

• Patient with Ventricular failure

• If heard in adult – cardiac abnormality (eg. Mitral regurgitation)

S4 (the atrial sound) is due to atrial systole

FOURTH HEART SOUND-S4

• Not heard in normal subjects

• Only recorded

• Just before first heart sound

• Atrial systole causes vibrations of atrial wall, AV valves and ventricular walls

• Heard in abnormal conditions – hypertrophy of atrium

• Absent in atrial fibrilation

Murmur is defined as a new cardiac sound unrelated to the four heart sounds.

A murmur is generally caused by prolonged turbulent flow in either diastole or systole typically related to valvular stenosis or regurgitation but may also be caused by abnormal connections between right and left heart circulations.

A murmur is best heard in area corresponding to heart valves.

Sounds Created by Turbulent Flow

• Stenosis, e.g., aortic stenosis• High output, low viscosity, e.g., anemia• Dilated chamber, e.g., aortic aneurysm• Reverse flow across a heart valve, e.g.,

valvular insufficiency• Shunting of blood, e.g., ventricular

septal defect, patent ductus

murmurs

Ejection murmur

Pansystolic murmur

Late systolic murmur

Early murmur

Mid to late murmur

Systolic murmurs

1. Mitral regurgitation (Pansytolic/ holosystolic, also seen in VSD and tricuspid regurgitation)

2. Aortic Stenosis (Mid-systolic)

Diastolic murmurs

1. Mitral stenosis

2. Aortic Regurgitation

Continuous murmur

1. Patent Ductus Arteriosus (Continuous machinary murmur)

The harsh systolic murmur of aortic stenosis

The diagnosis is confirmed by demonstrating a pressure gradient across the aortic valve.

Pressure gradient

Case

• A 65-year-old man presents to his primary care physician complaining of dyspnea, chest pain, and several syncopal episodes. His symptoms have worsened over the past few months and his third syncopal episode prompted this visit.

• On examination, a systolic ejection murmur is auscultated with an ejection click in the right second intercostal space. Rales are present at the lung bases. He has a history of rheumatic fever in his twenties

• Which of the following is the most likely diagnosis?

• A. Aortic regurgitation• B. Aortic stenosis• C. Mitral stenosis• D. Tension pneumothorax• E. Thoracic aortic dissection

Case • A 46-year-old woman presents to the emergency

department with fever, chills, and chest discomfort for 2 weeks.

• She admits to a 20 year history of intravenous drug use, and her last use was 3 weeks ago. Her temperature is 38.3 C (101 F), blood pressure is 120/52 mm Hg, pulse is 120/min, and respirations are 26/min.

• Her jugular venous pulse is normaI, but there are bibasilar crackles on lung examination.

• Cardiac examination reveals a rapid but regular rhythm and a new decrescendo, blowing diastolic murmur heard best over the right second intercostal space. The electrocardiogram shows sinus tachycardia.

• Which of the following is the most likely cause of her cardiac murmur?

• A. Aortic regurgitation• B. Aortic stenosis• C. Mitral regurgitation• D. Mitral stenosis• E. Mitral valve prolapse

• Aortic Stenosis• Mitral Regurgitation• Pulmonic Stenosis• Tricuspid Regurgitation• Volume Overload of left ventricle• Volume overload of right ventricle

• Auscaltation findings recorded at the left sternal border are presented below.

• Which of the following is the most likely cause of the murmur?

• Mitral Stenosis• Mitral Regurgitation• Aortic Stenosis• Pulmonary Regurgitation• Tricuspid Regurgitation

• Pathologic thickening and fusion of the valve leaflets that decreases the open valve area, creating a major resistance point in series with the systemic circuit.

• Ventricular systolic pressure increases (increased afterload) to overcome the increased resistance of the aortic valve

• Pressure overload of the left ventricle leads to a compensatory concentric hypertrophy (new sarcomeres laid down in parallel so that the myofibril thickens) which leads to decreased ventricular compliance (diastolic dysfunction) and coronary perfusion problems and eventually systolic dysfunction.

• Prominent “a” wave of the left atrium as the stiffer left ventricle becomes more dependent on atrial contraction for filling.

• Systolic murmur that begins after S1 (midsystolic) which is crescendodecrescendo in intensity.

• Slow closure of the aortic valve can cause a paradoxical splitting of the second heart sound (aortic valve closes after the pulmonics)

Early murmur

• The aortic valve does not close properly at the beginning of diastole.

• As a result, during diastole there is retrograde flow from the aorta into the ventricle.

• The amount of blood regurgitated into the left ventricle during diastole may be as much as 60–70% of the amount ejected during systole.

• Very large left ventricles are seen in aortic insufficiency.

• All the cardiac volumes are increased (EDV, ESV, SV).

• Increased preload causes increased stroke volume, which results in increased ventricular and aortic systolic pressures.

• Retrograde flow from the aorta to the left ventricle produces a low aortic diastolic pressure.

• Aortic insufficiency is characterized by a large aortic pulse pressure and a low aortic diastolic pressure.

• Dilation of the ventricle produces a compensatory eccentric hypertrophy.

• A narrow mitral valve impairs emptying of the left atrium (LA) into the left ventricle (LV) during diastole. This creates a pressure gradient between the atrium and ventricle during filling.

• Pressure and volume can be dramatically elevated in the left atrium, dilation of the left atrium over time, which is accelerated with atrial fibrillation.

• Left atrial pressures are elevated throughout the cardiac cycle. Increased left atrial pressures transmitted to the pulmonary circulation and the right heart.

• Little change or a decrease in the size of the left ventricle. Systolic function normal.

• Diastolic murmur begins after S2 and is associated with altered atrial emptying; a late diastolic murmur and an exaggerated “a” wave are associated with atrial contraction.

• Can result from structural abnormalities in the valve itself, papillary muscles, chordae tendinae, or possibly a structural change in the mitral annulus.

• No true isovolumetric contraction. Regurgitation of blood from the left ventricle to the left atrium throughout ventricular systole.

• Atrial volumes and pressures increased but chronic dilation of the atrium prevents a dramatic rise in atrial pressures.

• Ventricular volumes and pressures are increased during diastole, but there is no pressure gradient between the atrium and ventricle.

• Increased preload but with normal or reduced afterload.

• Systolic murmur that begins at S1 (pansystolic)

A. Tricuspid regurgitationB. Aortic stenosisC. Mitral regurgitationD. Mitral stenosisE .pulmonary stenosisF. Aortic regurgitation