Loud:MS, short PR interval, hyperkinetic heart, thin chest wall. Soft: Long PR interval, heart failure, mitral regurgitation, thick chest wall, pulmonary emphysema.
Normally A2 precedes P2 and splitting increases with inspiration; abnormalities include:
- Widened splitting: Right bundle branch block, PS, mitral regurgitation
- Fixed splitting (no respiratory change in splitting): Atrial septal defect
- Narrow splitting: Pulmonary hypertension
- Paradoxical splitting (splitting narrows with inspiration): Left bundle branch block, heart failure, AS
- Loud A2: Systemic hypertension
- Soft A2: Aortic stenosis
- Loud P2: Pulmonary arterial hypertension
- Soft P2: Pulmonic stenosis
Low-pitched, heard best with bell of stethoscope at apex, following S2; normal in children; after age 30-35, indicates LV failure or volume overload.
Low-pitched, heard best with bell at apex, preceding S1; reflects atrial contraction into a noncompliant ventricle; found in AS, hypertension, hypertrophic cardiomyopathy, and coronary artery disease (CAD).
High-pitched; follows S2 (by 0.06-0.12 s), heard at lower left sternal border and apex in MS; the more severe the MS, the shorter the S2-OS interval.
High-pitched sounds following S1 typically loudest at left sternal border; observed in dilation of aortic root or pulmonary artery, congenital AS or PS; when due to the latter, click decreases with inspiration.
At lower left sternal border and apex, often followed by late systolic murmur in mitral valve prolapse.
(Fig. 112-3. Graphical Representation of the Pressure; Tables 112-1 Heart Murmurs and 112-2 Effects of Physiologic and Pharmacologic Interventions on the Intensity of Heart Murmurs and Sounds)
Systolic Murmurs
May be “crescendo-decrescendo” ejection type, pansystolic, or late systolic; right-sided murmurs (e.g., tricuspid regurgitation) typically increase with inspiration.
Diastolic Murmurs
- Early diastolic murmurs: Begin immediately after S2, are high-pitched, and are usually caused by aortic or pulmonary regurgitation.
- Mid-to-late diastolic murmurs: Low-pitched, heard best with bell of stethoscope; observed in MS or TS; less commonly due to atrial myxoma.
- Continuous murmurs: Present in systole and diastole (envelops S2); found in patent ductus arteriosus and sometimes in coarctation of aorta; less common causes are systemic or coronary AV fistula, aortopulmonary septal defect, ruptured aneurysm of sinus of Valsalva.