Table 6: Auscultation – heart sounds

Physical Finding Associated cardiac condition(s)
First heart sound (S1)
Loud S1 Mitral stenosis, tricuspid stenosis, Lown-Ganong-Levine syndrome, tachycardia
Soft S1 Mitral regurgitation, severe congestive heart failure, calcified mitral valve, left bundle branch block, long PR interval (1st degree atrioventricular block)
Widely split S1 Right bundle branch block, Ebstein's anomaly, right atrial myxoma
Reversed splitting of S1 Severe mitral stenosis, left atrial myxoma, left bundle branch block
Variable intensity S1 Atrial fibrillation
Second heart sound (S2) Aortic valve closure (A2) and Pulmonary closure (P2)
Soft / absent A2 Severe aortic stenosis
Loud S2 - Loud A2 Systemic hypertension
Loud S2 - Loud P2 Pulmonary hypertension
Reduced splitting of S2 Pulmonary hypertension
Increased splitting of S2 - early A2 Mitral regurgitation
Increased splitting of - late P2: - electrical delay of P2 Right bundle branch block
Increased splitting of - late P2: - mechanical delay of P2 Pulmonary stenosis, ventricular septal defect, obstruction right ventricle, right ventricular failure, mitral regurgitation (with pulmonary hypertension)
Fixed splitting of S2 Atrial septal defect
Paradoxically split S2 - electrical delay of A2 left bundle branch block, right ventricular pacing, right ventricular ectopic beat (delayed excitation of left ventricular systole)
Paradoxically split S2 - mechanical delay of A2 Severe aortic outflow obstruction (aortic stenosis), systolic hypertension, large aorta-to-pulmonary artery shunt, ischemic heart disease, cardiomyopathy, aortic coarctation, patent ductusarteriosus
Single S2 (absence of physiologic splitting) Tetralogy, truncusarteriosus, tricuspid atresia
Muffled heart sounds Pericardial effusion
Third heart sound (S3)
S3 present, 0.14–0.16 seconds after S2 Ventricular septal defect, atrial septal defect, aortic regurgitation, mitral regurgitation, tricuspid regurgitation, patent ductusarteriosus, pregnancy, congestive heart failure, hyperdynamic circulation (fever, anemia, atrioventricular fistula, thiamine deficiency, hyperthyroidism, infection, Paget’s disease, pregnancy), physiological < 40 years old
Fourth heart sound (S4)
S4 present, 0.08-0.12 seconds before S1 Hypertension (systemic or pulmonary), hypertrophic cardiomyopathy, acute myocardial infarction, coronary artery disease, congestive heart failure, aortic stenosis, pulmonary stenosis