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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).
Opening Snap (OS)
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.