From the Guidelines
In Tetralogy of Fallot, a split S2 is typically absent due to the right ventricular outflow tract obstruction, which reduces blood flow through the pulmonary valve, making the pulmonary component of S2 (P2) faint or inaudible 1.
Clinical Significance
The absence of a split S2 in a cyanotic infant should raise suspicion for Tetralogy of Fallot, as opposed to other congenital heart defects where S2 splitting may be preserved or abnormally wide. This finding, combined with a harsh systolic ejection murmur at the left upper sternal border (from pulmonary stenosis) and cyanosis (from right-to-left shunting through the ventricular septal defect), forms the classic auscultatory pattern of Tetralogy of Fallot.
Key Points
- The pulmonary stenosis in Tetralogy of Fallot reduces blood flow through the pulmonary valve, making P2 faint or inaudible 1.
- The overriding aorta receives blood from both ventricles, making the aortic component of S2 (A2) more prominent 1.
- The absence of a split S2 is a key diagnostic feature of Tetralogy of Fallot, and its presence or absence can help differentiate it from other congenital heart defects 1.
- Regular follow-up with a cardiologist who has expertise in adult congenital heart disease is essential for patients with Tetralogy of Fallot, as they are at risk for complications such as pulmonary regurgitation, RV dilation and dysfunction, and sudden cardiac death 1.
From the Research
Significance of a Split S2 in Tetralogy of Fallot
- A split S2 is not directly mentioned in the provided studies as a significant factor in Tetralogy of Fallot 2, 3, 4, 5, 6.
- However, the studies discuss the importance of various diagnostic tools such as echocardiogram, cardiac magnetic resonance imaging, and cardiac catheterization in defining the unique anatomy of Tetralogy of Fallot for surgical correction 4.
- The presence of a split S2 is typically associated with an atrial septal defect or other conditions affecting the timing of the closure of the pulmonary and aortic valves, but its significance in Tetralogy of Fallot is not explicitly stated in the provided evidence.
- Tetralogy of Fallot is characterized by a ventricular septal defect, a large, overriding aorta, subpulmonic stenosis, and right ventricular hypertrophy, and its management involves surgical repair, which may include palliative procedures or complete repair 2, 3, 4, 5, 6.