Split S1
S1 is generated by closure of the mitral and tricuspid valves. These paired left- and right-sided valves do not close at exactly the same time, but the human ear cannot distinguish sounds that are 0.02-0.03 seconds apart as 2 separate sounds. When conditions further delay tricuspid valve closure, a split S1 can be appreciated. One of the most common causes of delayed tricuspid valve closure is a right bundle branch block.
Patient 1:
This patient was admitted to the hospital for a non-cardiac reason and was noted to have a split S1. You can hear two sounds in quick succession followed by a single S2. There was no clear cause of the split S1 in this case.
Split S1
Annotated
Patient 2:
A young healthy physician volunteered to have his heart recorded because of a known split S1. The underlying cause is unknown.
Split S1
Annotated
Patient 3:
This patient has split S1.
Split S1
Annotated
Patient 4
This is a young healthy woman who volunteered to have her heart sounds recorded. She has a split S1 of unclear significance