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Fourth Heart Sound Plus First Heart Sound

Virtual Auscultation

patient torso with stethoscope chestpiece
patient position during auscultation

The patient's position should be supine.

Lesson

Certain 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.

Waveform





Heart Sounds Video



Authors and Reviewers

Authored by Dr. Jonathan Keroes, MD and David Lieberman, Developer, Virtual Cardiac Patient. Medically reviewed by Dr. Barbara Erickson, PhD, RN, CCRN. Last Update: 11/28/2021


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