Essential Heart Sounds

Split Second Heart Sound | Auscultation #300 | Lesson with Audio

Where to Auscultate

patient thorax when auscultating by stethoscope

The patient was supine during auscultation.

Description

This lesson covers physiologic and paradoxical splitting of the second heart sound. As described earlier, the second heart sound is produced by the closing of the aortic valve and the closing of the pulmonic valve. These valves can close at slightly different times. This creates a split second heart sound. The second heart sound's splitting and intensity can indicate several types of cardiac abnormalities. In this recording, the splitting varies between zero and eighty milliseconds. The variation in splitting is a function 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 aortic stenosis and left bundle-branch block. Both of these abnormalities cause a delay in the aortic valve closure until after the pulmonic valve closure, reversing the normal sequence of events.

Phonocardiogram

Anatomy

Split Second Heart Sound

Authors and Sources

Authors and Reviewers

Heart sounds by Dr. Jonathan Keroes, MD and David Lieberman, Developer, Virtual Cardiac Patient.
Lung sounds by Diane Wrigley, PA
Respiratory cases: William French
David Lieberman, Audio Engineering
Heart sounds mentorship by >W. Proctor Harvey, MD
Special thanks for the medical mentorship of Dr. Raymond Murphy
Reviewed by Dr. Barbara Erickson, PhD, RN, CCRN.
Last Update: 11/10/2021

Sources

Heart and Lung Sounds Reference Library Diane S. Wrigley
Publisher: PESI
Impact Patient Care: Key Physical Assessment Strategies and the Underlying Pathophysiology
Diane S Wrigley & Rosale Lobo
Practical Clinical Skills: Lung Sounds
PESI Faculty - Diane S Wrigley
Case Profiles in Respiratory Care 3rd Ed, 2019
William A.French
Published by Delmar Cengage
Essential Lung Sounds by William A. French
Published by Cengage Learning, 2011
Understanding Lung Sounds Steven Lehrer, MD
Clinical Heart Disease W Proctor Harvey, MD
Clinical Heart Disease
Laennec Publishing; 1st edition (January 1, 2009)
Heart and Lung Sounds Reference Guide
PracticalClinicalSkills.com