splitting of S2

Introduction

• splitting of S2 represents asynchronous closure of aortic valve & pulmonic valve
• physiologic splitting of S2
  • single S2 during expiration, a double S2 during inspiration
• fixed splitting of S2 is nearly pathognomonic for atrial septal defect
• parodoxical splitting of S2
  • single S2 during inspiration, a double S2 during expiration
  • associated with aortic stenosis, left bundle branch block, right ventricular pacing

More general terms

• second heart sound (S2)