Discrete Heart Sounds

Discrete Heart Sounds: Excerpt from Field Guide to Bedside Diagnosis

Differential Overview

Phenomena

❑ S₄ gallop

❑ Midsystolic click

❑ S₃ gallop

❑ Loud S₂

❑ Widely split S₁

❑ Widely split S₂

❑ Ejection click

❑ Variable S₁

❑ Paradoxical splitting of S₂

❑ Loud S₁

❑ Fixed splitting of S₂

❑ Opening snap

❑ Pericardial knock

❑ Tumor plop

❑ Sail sound

Diagnostic Approach

The A₂-P₂ interval normally increases with inspiration due to decreased intrathoracic pressure and increased venous return, which leads to increased stroke volume.

In my southern medical school I was taught that the cadence of the S₃ gallop matches that of the spoken word Kentucky, and of S₄, Tennessee.

Clinical Findings

S₄ gallop  A low-pitched presystolic heart sound (heard best with the bell), it may be palpable at the left heart border. Caused by atrial contraction into a noncompliant ventricle, a fourth heart sound is often heard in hypertension with left ventricular hypertrophy, and in aortic stenosis, ischemic heart disease, and acute mitral regurgitation. Increased ventricular filling during atrial contraction, caused by anemia, thyrotoxicosis, or prolonged PR interval, can also produce an S ₄.

Midsystolic click  Heard in mitral valve prolapse, it may be a single click or multiple midsystolic clicks, often followed by a mitral regurgitant murmur. It moves in placement with maneuvers that change ventricular volume, such as positional change.

S₃ gallop  The third heart sound is a low-pitched early diastolic sound heard best at the apex with the bell. It is associated with the rapid ventricular
filling phase of the cardiac cycle, and its presence correlates with left ventricular dysfunction in congestive heart failure (ischemia, cardiomyopathy, myocarditis, cor pulmonale) or overload (acute valvular regurgitation, high output state, left-to-right shunt, complete heart block). In young adults, an S₃ may be a normal finding (a filling sound) due to a hyperkinetic heart or increased filling volume with mitral regurgitation.

Loud S₂  A₂ is increased in systemic hypertension. P₂ is increased in pulmonary hypertension.

Widely split S₁  Splitting may be produced by electrical delay of atrioventricular conduction in right bundle branch block, ventricular tachycardia, or left ventricular pacing.

Widely split S₂  If splitting is present both recumbent and standing, and is increased with inspiration, it suggests right bundle branch block, pre-
excitation, atrial septal defect, right ventricular pressure overload (pulmonary hypertension with right ventricular failure, severe pulmonary stenosis, or massive pulmonary embolism), or decreased resistance to left ventricular outflow (mitral regurgitation).

Ejection click  A sharp, high-pitched early systolic sound, it is associated with a bicuspid aortic valve, pulmonic stenosis, and aortic dilation.

Variable S₁  Beat-to-beat variation in intensity occurs with a variable PQ interval, such as occurs in Wenckebach, complete heart block, or atrial fibrillation.

Paradoxical splitting of S₂  Splitting decreases with inspiration, and is due to delayed aortic valve closure with left bundle branch block, severe aortic stenosis, hypertrophic cardiomyopathy, or severe left ventricular dysfunction, especially early in myocardial infarction. Differentiate A₂-P₂ from
A₂-OS by having the patient stand. A₂-OS widens, while A₂-P₂ narrows or is unchanged.

Loud S₁  An accentuated first heart sound occurs in hemodynamically significant mitral stenosis, hyperadrenergic states, and left atrial myxoma.

Fixed splitting of S₂  Splitting is not affected by Valsalva. It is found in atrial septal defect and severe right heart failure.

Opening snap  It is a high-pitched sound occurring shortly after the second heard sound. Usually associated with mitral stenosis, it is also heard in tricuspid stenosis. The greater the degree of stenosis, the closer the snap moves toward the second heart sound. It can be distinguished from a split S₂ by audibility over the sternal notch.

Pericardial knock  Caused by sudden restriction of ventricular filling by a thickened nondistensible pericardium, it occurs earlier in diastole than an S₃.

Tumor plop  The hallmark of an atrial myxoma, it occurs in the same part of the cardiac cycle as an S₃, but its timing varies.

Sail sound  This loud sound is produced by delayed tricuspid valve closure in Ebstein anomaly.

Book Source Details

• Book Title: Field Guide to Bedside Diagnosis
• Author(s): David S. Smith
• Year of Publication: 2007
• Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Field Guide to Bedside Diagnosis Authors: David S. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-78178-165-5

 » Next page: Valvular heart disease (Handbook of Diseases)

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