Fourth Heart Sound Plus First Heart SoundCertain heart sound configurations mimic a split first heart sound. One of these conditions is a fourth sound gallop (S4) plus a first heart sound (S1). Since the S4 occurs just before the S1, it is easy to confuse a S4/S1 with a split S1. An S4 is lower frequency than an S1. To differentiate between a S4/S1 and a split S1, listen carefully to the frequency of the initial sound of the pair. If it is lower in frequency than the second sound, it is an S4. If the two sounds are the same, it is a split S1.
Half Speed Patient Sounds
The patient's position should be supine.
Auscultation TipsDiastole:S4 present - a low-pitched sound
Observe Cardiac Animation
Authors and Sources
Authors and Reviewers
- EKG heart rhythm modules: Thomas O'Brien.
- EKG monitor simulation developer: Steve Collmann
12 Lead Course: Dr. Michael Mazzini, MD.
- Spanish language EKG: Breena R. Taira, MD, MPH
- Medical review: Dr. Jonathan Keroes, MD
- Medical review: Dr. Pedro Azevedo, MD, Cardiology
- Last Update: 11/8/2021
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
Cover Publishing Company
12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs
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