Identify both the anatomical location of impulses, heart sounds, and murmurs and where they fall in the cardiac cycle. Remember to integrate your findings with the characteristics of the patient's JVP and carotid upstroke.

■ Identify the anatomical location of cardiac findings in terms of interspaces and the distance of the PMI from the midclavicular (or midsternal) line. The midsternal line offers the most reproducible zero point for measurement, but some experts recommend the midclavicular line due to its better correlation with left ventricular pathology, as long as the midpoint between the cromioclavicular and sternoclavicular joints is carefully identified.

■ Identify the timing of impulses, sounds, and murmurs in relation to the cardiac cycle. Timing of sounds is often possible through auscultation alone, but aided by inspection and palpation as well. In most patients with normal or slow heart rates, it is easy to identify the paired heart sounds of S1 and S2 that mark the onset of systole and diastole. The relatively long diastolic interval after S2 separates one pair from the next (Fig. 1).

FIGURE 1. Diastole (S2 to S1) lasts longer than systole (S1 to S2).

The relative intensity of S1 and S2 is also helpful. S1 is usually louder than S2 at the apex; S2 is usually louder than S1 at the base.

"Inching" your stethoscope also helps clarify the timing of S1 and S2. Return to a place on the chest, typically the base, where it is easy to identify S1 and S2. Get their rhythm clearly in mind. Then inch your stethoscope down the left sternal border in steps until you hear changes in the sounds.

At times, the intensities of S1 and S2 may be abnormal, or at rapid heart rates the duration of diastole may shorten, making it difficult to distinguish systole from diastole. Palpation of the carotid artery during auscultation is an invaluable aid to the timing of sounds and murmurs. Since the carotid upstroke always occurs in systole immediately after S1, sounds or murmurs coinciding with the upstroke are systolic; sounds or murmurs following the carotid upstroke are diastolic.

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