What is the most likely characteristic of the heart sounds?

A three-year old male patient who has just been diagnosed with tetralogy of Fallot (TOF) presents to your office for a routine well- child checkup. His condition presented when his parents noticed that he was squatting frequently and seemed to be in distress. After having been given a referral for a pediatric cardiologist, they were informed that the squatting helps to compress the femoral arteries which increases systemic vascular resistance and decreases the right to left shunting present in TOF. When auscultating the heart on physical exam, what is the most likely characteristic of the heart sounds?

1.Fixed splitting of S1
2.Fixed splitting of S2
3.Normal splitting of S2
4.Paradoxical splitting of S2
5.Wide splitting of S2

Correct answer
Wide splitting of S2

Wide splitting of S2 (choice E) is most commonly seen in pulmonic stenosis due to lengthening of right ventricular ejection time. This pulmonic stenosis one of the four components of the Tetralogy. The other four components are ventricular septal defect, overriding aorta, and right ventricle hypertrophy.
Fixed splitting of S1 (choice A) can result from conduction disturbances, hemodynamic, or mechanical causes but is not usually heard on physical exam.

Fixed splitting of S2 (choice B) is usually seen with an atrial septal defect or with right bundle branch block. The mechanisms for each of these is either increased blood flow in the case of an atrial septal defect or a delay in conduction in the case of a right bundle branch block.

In normal splitting of S2 (choice C), you see an increased time between the closure of the aortic valve and the pulmonic valve at the end of systole during inspiration due to pooling of blood in the pulmonic vasculature.

Paradoxical splitting of S2 (choice D) is when the aortic valve closes after the pulmonic valve. This can occur in aortic stenosis due to similar mechanisms described above for the wide splitting found in pulmonic stenosis.