Bedside cardiac examination: constancy in a sea of change

Abstract

The general trend in the recent literature has been to highlight the difficulties and shortcomings of the physical examination and to attribute these difficulties to deficiencies in training rather than to intrinsic weaknesses in auscultation itself. The call is for better training. Given the advice of the authors mentioned above, individual training may be warranted at the postgraduate level and in the large community of practicing internists and cardiologists. Although not proven, it is likely that individual training with computer technology, audiotape instruction, or simulator technology such as described in the following paragraphs would be effective at improving bedside clinical diagnosis and cost-effective patient care in the postgraduate, continuing medical education setting. The advances in auscultation during the last few years have been more incremental than fundamental. There is ongoing research into the mechanism of production of S3 and S4, and mathematical modeling techniques have recently been used with some success in evaluating the vibrations of S3 and S4 as forced, damped oscillations of a viscoelastic system. Analysis of sound energy with the technique of spectral waveform analysis, which investigates the frequency content of sound signals, has been used for many years in the study of cardiovascular sound. By the use of various methods of mathematical analysis, investigators have found potentially useful information in spectral sound patterns of prosthetic valves, murmur characteristics, and even potentially hemodynamic information from heart sounds. Despite the mathematical advances, there are still disturbing drawbacks to some of the analytic techniques, such as the production of mathematical terms containing "negative energy." Although the potential of obtaining significant clinical information from spectral analysis of heart sound recordings is attractive, the clinical usefulness of such techniques remains virtually nonexistent. Similar to the recent advances in auscultation, the technical advances in the design of the stethoscope have also been more incremental than fundamental. There are at least 3 recently introduced electronic stethoscopes that have the capability of amplification and filtration and that claim noise reduction. Because their introduction is recent, no information is available in the peer-review literature regarding their clinical performance; therefore their place in the clinical arena remains to be elucidated--perhaps a boon for patient care providers with specific hearing defects and perhaps useful in noisy clinical environments. Peer-review literature has not shown clear superiority of one type of acoustic stethoscope over another. The teaching of auscultation has been an area of recognized importance in patient care since the inception of auscultation as a medical art. Attempts to facilitate practitioner learning in the performance and interpretation of auscultation have advanced through the decades limited only by the technical infrastructure of the day. The availability of recorded heart sounds and murmurs appeared shortly after the availability of recording and playback devices, with first vinyl and later tape recordings. In 1974, technology was employed to create a virtual patient named "Harvey," an engineered cardiology patient simulator that reproduces many of the physical findings of the cardiology examination. Later, with the advent of commercially available CD-ROM devices, newer, better-integrated teaching devices have been developed, some of them outstanding in their clarity and quality. Despite the obvious value of such instructional aids that are best used in the individual setting, there is evidence that the classroom is still of significant value in teaching auscultation. However, nowhere else in the practice of medicine is a mentor approach more valuable than in learning auscultation. (ABSTRACT TRUNCATED)