Cardiology

Question 1

Cause of physiological splitting of S2:

Answer 1

• Inspiration delays closure of the pulmonary valves by about 30—60 milliseconds due to increased venous return and decreased pulmonary vascular resistance. This is called the physiological splitting of S2.

Question 2

Abnormal splitting of S2 (3 types and mechanical explanations)

Answer 2

• Wide splitting of S2: An exaggerated (persistent) physiological split that is more pronounced during inspiration.
• Fixed splitting of S2: Fixed delay of P2 closure due to increased right-sided volume (ASD or advanced RV failure).
• Reversed or paradoxical splitting of S2: Aortic valve closure delayed due to obstruction (AS) or conduction disease (LBBB). Split narrows with inspiration as pulmonic valve closure is delayed moving P2 closer to a delayed A2 where the sound becomes single.