Normal Heart Sounds

Normal First and Second Heart Sounds Lesson #654

patient thorax when auscultating by stethoscope

The patient was supine during auscultation.

Description

This is a normal first and second heart sound at 60 beats per minute. You are auscultating at the Mitral valve area (Apex). The first heart sound has slightly greater intensity than the second

This page presents normal first and second heart sounds with a heart rate of 60 bpm. Auscultate these sounds at the mitral valve area (apex) or tricuspid area. Often the first heart sound will be louder than the second heart sound.

The first heart sound is produced by the closing of the mitral and tricuspid valve leaflets. The mitral sound (M1) typically occurs before the tricuspid sound (T1). T1 and S1 splitting can be best heard at the tricuspid location. If M1 and T1 are separately distinguished, this is called an S1 split. S1 splitting is common in children. An S1 split can be associated with EKG-related abnormalities such as right bundle branch block, premature ventricular contractions, or ventricular tachycardia in adults.

The second heart sound is produced when the aortic and pulmonic valve leaflets close. S2 splitting will be presented in the next module.

Phonocardiogram

Anatomy

Normal First and Second Heart Sounds

The first heart sound is produced by the closing of the mitral and tricuspid valve leaflets. The second heart sound is produced by the closing of the aortic and pulmonic valve leaflets.

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
Essential Lung Sounds Diane S. Wrigley, PA-C
Published by MedEdu LLC
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