Third Heart Sound 635 Lesson

patient thorax when auscultating by stethoscope

patient position during auscultation
The patient was supine during auscultation.

Description

A third heart sound (S3) occurs early in diastole, just after the second heart sound. S3 is a low-frequency sound best heard using the bell of the stethoscope pressed lightly on the skin of the chest. Position the chestpiece at the left lateral sternal border (LLSB) or xiphoid area.

Sudden deceleration of blood flow into the left ventricle from the left atrium causes the third heart sound. In the anatomy video, observe the thin-walled, dilated left ventricle with generalized decreased vigor of contraction.

In the presence of a third heart sound (S3), the first heart sound decreases in intensity while the second heart sound increases in intensity

In young people and athletes, it is a normal phenomenon. In older individuals, it indicates the presence of heart disease.

Phonocardiogram

Anatomy

Third Heart Sound 635


Authors and Sources

Authors and Reviewers

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




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