The Third & Fourth (S3 &S4) Chapter 9 Are G. Talking, MD, FACC Instructor Patricia L. Thomas, MBA, RCIS

Outline Diastolic Filling The Third Heart Sound Summation Gallop Differential Diagnosis Absent S3 & S4 The Fourth Heart Sound

Diastolic Filling Reflects Ventricular Function S3 heard in systolic left ventricular dysfunction S4 heard in diastolic left ventricular dysfunction Two periods of accelerated ventricular filling Passive filling early diastole after AV valves open Active filling occurring late diastole results from atrial contraction (A-Kick)

Early or Passive Filling Begins when the mitral valve opens Rapid filling of the LV follows Soft positive wave (RFW) rapid filling can cause a physiological S3 in young or in high flow states Pathological S3 or ventricular diastolic gallop in cases of dilated hearts and in CHF

Late or Active Filling Atrial systole forces blood into the ventricle in late diastole Forward thrust of blood is normally silent If ventricle is stiff/reduced compliance, the force of blood entering the ventricle is more vigorous and results in an impact sound in late diastole know as S4 or atrial gallop Hypertension, outlet obstruction, hypertrophy/infiltrative myopathies

Where To Listen Listen with the bell at the PMI after patient turn to left lateral position

The Third Heart Sound S3 Originate in either or both ventricles most commonly in the LV and resulting in vibrations of the LV wall Relates to a sudden deceleration of early diastolic LV inflow caused by a sudden limitation of expansion along the longitudinal axis of the LV wall resulting in a negative jerk that is transmitted to the skin surface High inflow rates with mitral regurgitation Incomplete relaxation

Normal S3 Present in children and well-conditional young athletes Persist in ¼ of individuals until about 40 Predicted by leanness and high early diastolic LV inflow velocity which reflects effects of aging Normal disappearance with age due to increased myocardial mass, larger mass increase damping factor and less vibrations

Pathological S3 (Gallop Rhythm) S3 or S4 produces a triple rhythm S3 & S4 produces a quadruple rhythm that sounds like the galloping of a horse in both normal/abnormal clinical situations Causes Mitral Regurgitation Aortic Stenosis Acute Myocardial Infarction Evolving Heart Failure S3 Induced by Exercise

Differential Diagnosis Normal vs. Abnormal S3 or S4 Right vs. Left Ventricular S3 Right Ventricular S3 is louder during inspiration because of increased venous return to the RV and a larger stroke volume

The Fourth Heart Sound (S4) Caused by the vibration created in the ventricles as they expand in the second phase of rapid diastolic filling when the atria contract and before the first heart sound Fourth heart sounds seldom occur in normal hearts Pathological S4 is a low-frequency, dull or thudding sound resulting from the sudden movement of stiff ventricular wall as they respond to the force delivered through the AV valves by the enhanced contraction of the atria

Where to Listen/Loudness of S4 Listen with the bell at the PMI with patient in the left lateral decubitus position It is louder on expiration Louder with increased preload or afterload (squatting, hand grip, leg elevation) increases the intensity of S4 because it shortens the P-S4 interval

S4 & the PR Interval Easily heard when the PR interval is prolonged Interval from the P wave to S4 varies and influences prognosis

THE END OF CHAPTER 9 Tilkian, Ara MD Understanding Heart Sounds and Murmurs, Fourth Edition, W.B. Sunders Company. 2002, pp. 93-106