ECG Basics

Opening Snap and Second Heart Sound 362

This is an opening snap occurring early in diastole along with a single second heart sound can mimic a split second heart sound. An opening snap is caused by thickened valve leaflets. When they open it produces a snapping sound. The more severe the thickening the earlier in diastole the opening snap occurs. In this example you are hearing an opening snap which occurs 75 milliseconds after the start of the second heart sound.

Listen

patient torso with stethoscope at aortic position

patient torso with stethoscope at Erb's Point position

patient torso with stethoscope at tricuspid position

patient torso with stethoscope at mitral position

Authored by Dr. Jonathan Keroes, MD, Cardiology
Medically reviewed by Dr. Barbara Erickson, PhD, RN, CCRN. Last Update: 11/18/2020