Techniques: Heart Sounds & Murmurs

1st & 2nd Heart Sounds

Note: The first heart sound can usually be heard easily with both the bell and the diaphragm but the diaphragm is invaluable for analyzing the second heart sound, with the stethoscope usually best placed at the midleft sternal edge.

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First Heart Sound

Loud Heart Sound

• Hyperdynamic (fever, exercise)
• Mitral stenosis
• Atrial myxoma (rare)

Soft First Sound

• Low cardiac output (rest, heart failure)
• Tachycardia
• Severe mitral reflux (caused by destruction of valve)

Variable Intensity of First Sound

• Atrial fibrillation
• Complete heart block

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Second Heart Sound

Audible expiratory splitting means > 30 msec difference in the timing of the aortic (A₂) and pulmonic (P₂) components of the second heart sound.

• Splitting of S₂ is best heard over the 2nd left intercostal space
• The normal P₂ is often softer than A₂ and rarely audible at apex
  • Differential Diagnosis of P₂ audible at apex
    • Significant pulmonary hypertension
    • Atrial septal defect
• Findings should be present in both upright and supine positions: normal subjects may have expiratory splitting when recumbent that disappears when upright.

Split S2

Type	Inspiration	Expiration	Cause
Normal or physiologic
Wide, fixed splitting			Atrial septal defect
Wide split, varies with inspiration			Pulmonary stenosis, RBBB
Paradoxical splitting			Hypertrophic cardiomyopathy

Loud Aortic Component of Second Sound

• Systemic hypertension
• Dilated aortic root

Soft Aortic Component of Second Sound

• Calcific aortic stenosis

Loud Pulmonary Component of Second Sound

• Pulmonary hypertension

Proceed to the next technique

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