Second Heart Sound (S2)

S2 is caused by the closure of the aortic valve (A2) closely followed by that of the pulmonary valve (P2)

Causes of a loud S2

• hypertension: systemic (loud A2) or pulmonary (loud P2)
• hyperdynamic states
• atrial septal defect without pulmonary hypertension

Causes of a soft S2

• aortic stenosis

Causes of fixed split S2

• atrial septal defect

Causes of a widely split S2

• deep inspiration
• RBBB
• pulmonary stenosis

long RV systole 2° RV dilatation due to Tricuspid Regurgitation in long-standing Pulm: Regurgitation

• severe mitral regurgitation
• VSD