Second Heart Sound - Splitting 118

This lesson covers physiologic and paradoxical splitting of the second heart sound. The second heart sound (S2) is created by the closing of the aortic valve and the closing of the pulmonic valve. The difference in timing between the closure of the aortic and pulmonic valves creates a split second heart sound. Careful analysis of the splitting and intensity of the second heart sound can indicate the presence of many cardiac abnormalities. In this example splitting varies between zero and eighty milliseconds depending on the phase of the respiratory cycle. In physiologic splitting the maximum separation between aortic and pulmonic components of the second heart sound occurs at peak inspiration. In paradoxical splitting the maximum separation occurs at peak expiration. Paradoxical splitting can occur with left bundle-branch block (LBBB) and aortic stenosis both of which cause the aortic valve closure to be delayed until after the pulmonic valve closure, reversing the normal sequence of events.

Second Heart Sound - Splitting 118 Audio

Second Heart Sound - Splitting 118 auscultation sound from lesson

Technique

The patient's position should be supine.

Auscultation Tips for Second Heart Sound - Splitting 118

S2:Splitting during inspiration

Sound Wave

Second Heart Sound - Splitting 118 Video

Authors and Sources

Authors and Reviewers

ECG heart rhythm modules: Thomas O'Brien.
ECG monitor simulation developer: Steve Collmann
12 Lead Course: Dr. Michael Mazzini, MD.
Spanish language ECG: Breena R. Taira, MD, MPH
Medical review: Dr. Jonathan Keroes, MD
Medical review: Dr. Pedro Azevedo, MD, Cardiology
Last Update: 11/8/2021

Sources

Electrocardiography for Healthcare Professionals, 6th Edition Kathryn Booth and Thomas O'Brien
ISBN10: 1265013470, ISBN13: 9781265013479
McGraw Hill, 2023
Rapid Interpretation of EKG's, Sixth Edition
Dale Dublin
Cover Publishing Company
EKG Reference Guide
EKG.Academy
12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs
Aaron Reed
Create Space Independent Publishing
Heart Sounds and Murmurs: A Practical Guide with Audio CD-ROM 3rd Edition
Elsevier-Health Sciences Division
Barbara A. Erickson, PhD, RN, CCRN
The Virtual Cardiac Patient: A Multimedia Guide to Heart Sounds, Murmurs, EKG Jonathan Keroes, David Lieberman
Publisher: Lippincott Williams & Wilkin)
ISBN-10: 0781784425; ISBN-13: 978-0781784429
Project Semilla, UCLA Emergency Medicine, EKG Training Breena R. Taira, MD, MPH
ECG Reference Guide
PracticalClinicalSkills.com

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