phonocardiograms

Phonocardiograms are graphical representations of heart sounds and murmurs produced by phonocardiography, the process of recording acoustic signals from the chest and displaying them as waveforms or spectrograms. They provide a time-based record of cardiac sounds, allowing analysis of the major components S1 and S2 and any additional sounds or murmurs beyond auscultation alone.

Acquisition and processing involve placing a sensitive microphone or electronic stethoscope on the chest to capture cardiac sounds. Signals are amplified, filtered, and digitized for display. Common processing steps include band-pass filtering, rectification, and sometimes spectrographic visualization to show frequency content over time, aiding interpretation of sound characteristics.

Interpreting a phonocardiogram focuses on the timing of heart sounds within the cardiac cycle, the relative intensity and duration of S1 and S2, and the presence of extra sounds such as S3 or S4 or murmurs. Clinicians assess the onset and contour of sounds, their relation to systole and diastole, and how murmurs change with respiration or position. When available, aligning the phonocardiogram with an ECG can provide precise timing references.

Clinical use and status: Phonocardiography has historical importance as a diagnostic aid and teaching tool. In contemporary practice it is largely supplementary to imaging modalities such as echocardiography and Doppler, but it remains of value in research, education, and certain bedside or recording settings to document and analyze heart sounds and murmurs.

Limitations include sensitivity to chest wall thickness, motion and environmental noise, the need for specialized expertise to interpret the traces, and the fact that it is not routinely used as a primary diagnostic tool in many settings. See also auscultation, echocardiography, and Doppler imaging.