PRE-CLINICAL CLERKSHIP, YEAR 1
Session Four: Heart Sounds
Cheryl A. Walters, M.D.
(VH Dissector Pro Images: Lawrence Rizzolo, Ph.D.)
1. Learning Objectives
- To outline on the chest, the maps for auscultating the aortic, pulmonic, Erb’s point, tricuspid, and mitral areas.
- To practice the techniques of examining the heart sounds (positioning, sequencing, handling of the stethoscope)—inspection, palpation, auscultation.
- To describe and appreciate the defining features of S1, S2, systole and diastole.
- To develop a flow for the head to toe exam.
2. Student Prep
Read pp. 390-399, 407-429, Chapter 14 The Heart
- View the companionportion of the CD
- Practice Exercises:
Inspection: Identify on yourself or partner the aortic (2nd Right intercostal space), pulmonic (2nd Left ICS), tricuspid (4th L ICS), and mitral (5th L ICS) areas and Erb’s point (3rd L ICS). Identify the sternal angle or angle of Louis (helpful in measuring JVD).
Auscultation: Read the attached article, “Listening to the Heart: Dying Art?” Listen to the recording of heart sounds on the CD. Practice using the diaphragm of your stethoscope to listen to your own or partner’s heart to identify the first (S1) and second (S2) heart sounds, and the systolic and diastolic phases.
Three defining features are helpful in discriminating S1/S2, systole/diastole:
- cadence or relative length of the phases
- At slow to normal heart rates (less than 100 beats/min), systole is shorter than diastole and the heartbeat is appreciated as a repeating pattern (or cadence) of two grouped sounds followed by a pause: lub/dup (S1/S2), pause, lub/dup, pause….. The short phase between the two grouped sounds S1 and S2 is systole, and the longer pause is diastole.
- At heart rates 100 or greater the phases become equal, the cadence is similar to a ticking watch, and discrimination is difficult.
- location , location, location
- At the 2nd L ICS, S2 is much louder than S1. Practice listening over the 2nd L ICS to identify S2 as the louder sound, and then inch slowly along the left sternal border (listen at Erb’s point, the tricuspid area and the mitral area at the apex). As you inch along, notice S2 becoming fainter and S1 becoming louder. In a healthy person, at the apex S1 is louder than S2.
- timing of S1 with apical beat or carotid pulse
The apical heartbeat (often visible in thin, young patients, and palpable in many patients esp. in the left lateral decubitus position) coincides with S1. The carotid upstroke is just after S1.
3. Clinical Anatomical Landmarks (use ctrl-p or command-p to reveal or hide the plane of the axial image)
The internal jugular pulsation is beneath the sternocleidomastoid muscle and is sometimes visible by shining a light on the overlying tissue at an angle. The vein itself is not visible.
The external jugular vein is visible lateral to the sternocleidomastoid muscle.