First Heart Sounds

Fourth Heart Sound (S4) Plus First Heart Sound - Auscultation 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.

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The patient's position is supine.

Fourth Heart Sound (S4) Plus First Heart Sound - Auscultation Lesson

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