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Fixed wide splitting of S2

• Diagnostic finding of ostium secundum ASD.
• Components separated during expiration and vary little with inspiration.
• Wideness is due increase capacitance of pulmonary vascular bed.
• Fixed wideness is due to marked increase of pulmonary capacitance that changes little with inspiration and to offsetting changes in left-to-right shunt with respiration.

Reversed splitting of S2

• S2 narrows with inspiration, widens with expiration.
• Often reflects left ventricular dysfunction.
• Reversed S2 - Delayed A2 – Electrical
1. LBBB (proximal)
2. RV pacing
3. RV ectopy
• Reversed S2 - Delayed A2 – Mechanical (prolonged LV systole)
1. LBBB (peripheral)
2. LV outflow obstruction
3. Ischemic heart disease
4. Hypertensive heart disease
5. Early P2
6. Early RV activation - WPW (type B)