First Heart Sound - Decreased Intensity
A decreased intensity first heart sound can be produced by various heart abnormalities, such as a viral infection of the heart called a cardiomyopathy. Other conditions include a previous heart attack and decreased thyroid function. The decreased intensity first heart sound is due to a decrease in the vigor of contraction of the left ventricle. See the anatomy video.Auscultation Sounds
Position
The patient's position should be supine.
Listening Tips
S1:Reduced intensityWaveform (Phonocardiogram)
Observe Cardiac Animation
A decrease in the vigor of contraction of the left ventricle causes decreased intensity first heart sound.
Authors and Sources
Authors and Reviewers
- EKG heart rhythm modules: Thomas O'Brien.
- EKG monitor simulation developer: Steve Collmann
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12 Lead Course: Dr. Michael Mazzini, MD.
- Spanish language EKG: Breena R. Taira, MD, MPH
- Medical review: Dr. Jonathan Keroes, MD
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Heart sounds and mentorship: W. Proctor Harvey, MD
- Medical review: Dr. Pedro Azevedo, MD, Cardiology
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Last Update: 1/8/2023
Sources
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Electrocardiography for Healthcare Professionals, 5th Edition
Kathryn Booth and Thomas O'Brien
ISBN10: 1260064778, ISBN13: 9781260064773
McGraw Hill, 2019 -
Rapid Interpretation of EKG's, Sixth Edition
Dale Dublin
Cover Publishing Company -
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 - Clinical Heart Disease
W Proctor Harvey, MD
Clinical Heart Disease
Laennec Publishing; 1st edition (January 1, 2009) -
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
First Heart Sound - Decreased Intensity | #41
