Overview
Reading Heart Sounds as Timing Clues
An auscultated heart sound is a mechanical event translated into a timing clue.
An auscultated heart sound is a mechanical event translated into a timing clue. Start with the cardiac cycle: S1 begins ventricular systole, and S2 ends it. Then characterize any separation or added sound by when it occurs, where it is loudest, whether respiration changes it, and whether the rhythm and symptoms make it plausible. This prevents a common error—naming a sound without asking what changed in ventricular filling or ejection. The same sound can have different significance in different patients. An inspiratory S2 split may be normal, an S3 may be physiologic in pregnancy or a young athlete, and an S3 with new dyspnea and edema may signal congestion. Auscultation narrows the clinical question; it does not establish or exclude structural heart disease or heart failure. Abnormal timing, a new gallop, fixed or paradoxical splitting, or an unusually prominent P2 should be correlated with rhythm, perfusion, lung findings, volume status, and objective testing.