S2 Heart Sounds ((hot)) Instant

In Atrial Septal Defect (secundum type), chronic right ventricular volume overload prolongs RV systole. The split becomes "fixed" because respiration cannot further alter the already maximal delay of P2.

| Condition | S2 Intensity | Splitting Pattern | Respiratory Variation | Other Clues | | :--- | :--- | :--- | :--- | :--- | | | Normal A2 > P2 | Physiologic | Present (widens on inspiration) | Asymptomatic | | Hypertension | Loud A2 | Physiologic | Present | Elevated BP | | Pulmonary HTN | Loud P2 (may equal or exceed A2) | Narrow or single | Minimal | Right ventricular heave | | Aortic Stenosis | Soft/absent A2 | Paradoxical (if severe) | Reversed | Late-peaking murmur | | ASD | Normal or wide | Wide fixed | Absent | Systolic murmur at LUSB | | LBBB | Normal | Paradoxical | Reversed | Wide QRS on ECG | | RBBB | Normal | Wide physiologic or fixed | Present or absent | Wide QRS on ECG | s2 heart sounds

| Finding | A2 | P2 | Common Causes | | :--- | :--- | :--- | :--- | | | Increased | Increased | Systemic hypertension (loud A2), Pulmonary hypertension (loud P2), thin chest wall. | | Soft S2 | Decreased | Decreased | Aortic stenosis (reduced valve mobility), severe hypotension, obesity/emphysema. | | Absent P2 | Normal | Absent | Pulmonary atresia, severe pulmonary stenosis. | In Atrial Septal Defect (secundum type), chronic right