In Conn and O’Keefe’s excellent review of physical diagnosis in the digital age, they chose to omit one very significant area of cardiac auscultation that has long had short shrift from instructors—the heart sounds—preferring to present only murmurs. (We have alluded to this in general elsewhere. ) If cardiologists can be analogized to astronomers, murmurs become analogous to the planets—more dramatic and easily noticed—but the heart sounds are analogous to the stars—harder to examine, but full of physiologic significance. The investigators correctly emphasized hemodynamic knowledge to interpret the physical examination. Indeed, cardiac examination using that perspective is best begun by starting with the second heart sound, noting its intensity, including palpability, and its splitting (normal, narrow, wide, reversed, fixed). This immediately puts the auscultator in a physiologic “mood,” because these variants of S2 have clinical, hemodynamic, and electric correlates. As for S1, its intensity, acoustic quality, palpability, and any splitting relate to the relative “energy” (power) of the ventricles, particularly the left, and electrical phenomena such as PR interval and bundle branch block. For example, acute myocardial infarction makes S1’s frequency spectrum shift downward, making S1 sound mushy; during favorable recovery, this reverses and S1 becomes clearer. The third heart sound, when not a physiologic S3, may be relatively soft, or loud—a sign of ventricular dilation and restriction; in constrictive pericarditis, it is loud and often palpable (these days a truly “knocking” quality is rare). The physiologic S3 is still poorly understood, but it occurs in many children and young adults, disappearing with increasing age. The fourth heart sound has been widely neglected and has been considered always to be a sure sign of ventricular abnormality. However, we showed this to be partly a function of the type of phonocardiographic equipment used. The Hewlett-Packard and Cambridge equipment common in the United States and the United Kingdom has sharp roll-offs at each filter frequency, which, unless a fourth heart sound is very intense, is insensitive to such sounds, which fed the common opinion that any S4 is always abnormal (Loud, palpable S4s, of course, as during angina, are intense and clearly abnormal.) Using the Hewlett-Packard phonocardiographic equipment mentioned and 2 other phonocardiographs with gentle roll-offs at each frequency (Siemens and Schwartzer), we were able to demonstrate audible fourth heart sounds in a large percentage of normal subjects aged >45 years. Subsequently, this accorded with the more recent demonstration in Doppler echocardiography that the normal ventricular A wave (produced by atrial systole) normally increases to equal and then exceed the normal E wave in subjects aged >45 years. We were also able to demonstrate phonic factors governing audibility of S4 using blinded auscultators as well as phonocardiography. One possible reason for the decrease of auscultation, as with electrocardiography, is not only that they became relatively less important in view of imaging and other advances but also that teaching continues to be weak.

This message is to supplement and not to criticize Conn and O’Keefe’s efforts, which are excellent and appropriately reported.