HEART SOUNDS
Auscultation is routinely performed over five specific areas of the heart to listen for corresponding valvular sounds. These auscultation sites are often referred to by the mnemonic “APE To Man,” referring to Aortic, Pulmonic, Erb’s point, Tricuspid, and Mitral areas (see Figure 9.8[17] for an illustration of cardiac auscultation areas). The aortic area is the second intercostal space to the right of the sternum. The pulmonic area is the second intercostal space to the left of the sternum. Erb’s point is directly below the pulmonic area and located at the third intercostal space to the left of the sternum. The tricuspid (or parasternal) area is at the fourth intercostal space to the left of the sternum. The mitral (also called apical or left ventricular area) is the fifth intercostal space at the midclavicular line.
Auscultation usually begins at the aortic area (upper right sternal edge). Use the diaphragm of the stethoscope to carefully identify the S1 and S2 sounds. They will make a “lub-dub” sound. Note that when listening over the area of the aortic and pulmonic valves, the “dub” (S2) will sound louder than the “lub” (S2). Move the stethoscope sequentially to the pulmonic area (upper left sternal edge), Erb’s point (left third intercostal space at the sternal border), and tricuspid area (fourth intercostal space. When assessing the mitral area for female patients, it is often helpful to ask them to lift up their breast tissue so the stethoscope can be placed directly on the chest wall. Repeat this process with the bell of the stethoscope. The apical pulse should be counted over a 60-second period. For an adult, the heart rate should be between 60 and 100 with a regular rhythm to be considered within normal range. The apical pulse is an important assessment to obtain before the administration of many cardiac medications.
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The first heart sound (S1) identifies the onset of systole, when the atrioventricular (AV) valves (mitral and tricuspid) close and the ventricles contract and eject the blood out of the heart. The second heart sound (S2) identifies the end of systole and the onset of diastole when the semilunar valves close, the AV valves open, and the ventricles fill with blood. When auscultating, it is important to identify the S1 (“lub”) and S2 (“dub”) sounds, evaluate the rate and rhythm of the heart, and listen for any extra heart sounds.
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