Fixed splitting of the second heart sound (R2)

Specialty: Cardiovascular.

• persistent and fixed splitting of R2
• doubling of the second heart sound not modifiable with respiration

Why it occurs

• Atrial interatrial communication of the ostium secundum, ostium primum or venous sinus type
• Complete right bundle branch block (RBBB)
• Chronic severe right ventricular failure
• Moderate to severe pulmonary valve stenosis with prolonged ejection
• Ventricular communication with large shunt from left to right

Initial workup

12-lead electrocardiogram to look for the rSR' pattern in right precordial leads (V1-V2) indicative of right bundle branch block, right axis deviation and right ventricular hypertrophy; Transthoracic and transesophageal Doppler echocardiogram to directly visualize the interatrial septal defect, measure the direction and speed of the shunt, estimate the pulmonary and systemic flow ratio (Qp/Qs) and quantify the degree of dilation of the right chambers; Chest x-ray.

Standard management

• Furosemide — loop diuretic indicated if there are data of fluid overload of the right cavities; 20 to 40 mg once daily orally
• Spironolactone — aldosterone receptor antagonist for water depletion and control of remodeling of the right cavities; 25 mg once daily orally
• Warfarin — oral anticoagulant indicated if associated with atrial fibrillation or flutter secondary to chronic atrial stretching, to prevent cardioembolic events; dose adjusted to INR between 2.0 and 3.0
• Enoxaparin (prophylaxis or treatment in the acute phase if there is suspicion of thrombosis or concomitant peripheral embolism; 1 mg/kg every 12 hours subcutaneously).