Differential Diagnosis for Wide Fixed Splitting of S2
Single Most Likely Diagnosis
- Atrial Septal Defect (ASD): This is the most common cause of wide fixed splitting of S2. The fixed splitting occurs due to the delay in closure of the pulmonary valve relative to the aortic valve, which is a result of the increased volume of blood flowing through the pulmonary valve due to the left-to-right shunt.
Other Likely Diagnoses
- Ventricular Septal Defect (VSD): Similar to ASD, VSD can cause increased flow through the pulmonary valve, leading to wide fixed splitting of S2, although the splitting may not always be fixed.
- Pulmonary Stenosis: Valvular or subvalvular pulmonary stenosis can delay the closure of the pulmonary valve, resulting in wide splitting of S2.
- Mitral Regurgitation: Severe mitral regurgitation can increase the volume of blood in the left atrium, leading to increased flow through the pulmonary valve and wide splitting of S2.
Do Not Miss Diagnoses
- Pulmonary Embolism: Although less common, a large pulmonary embolism can cause acute increase in pulmonary artery pressure, leading to wide splitting of S2. Missing this diagnosis can be fatal.
- Cardiac Tamponade: Cardiac tamponade can cause equalization of diastolic pressures, leading to wide splitting of S2. This is a life-threatening condition that requires immediate attention.
Rare Diagnoses
- Congenitally Corrected Transposition of the Great Arteries: This rare congenital heart defect can cause wide fixed splitting of S2 due to the abnormal anatomy of the great arteries.
- Ebstein's Anomaly: This congenital heart defect involves the tricuspid valve and can cause wide splitting of S2 due to the abnormal flow of blood through the pulmonary valve.
- Single Ventricle: Rare congenital heart defects where only one ventricle is present can cause wide splitting of S2 due to the abnormal hemodynamics.