Heart Sounds: S2

Key points

• S2 = closure of the aortic valve (A2) closely followed by the pulmonary valve (P2)
• Loud S2: hypertension (systemic → loud A2, pulmonary → loud P2) · hyperdynamic states · ASD without pulmonary hypertension · soft S2: aortic stenosis
• Fixed split: ASD · widely split: deep inspiration, RBBB, pulmonary stenosis, severe mitral regurgitation
• Reversed (paradoxical) split (P2 before A2): LBBB · severe aortic stenosis · right ventricular pacing · WPW type B · patent ductus arteriosus