Norm of Phonocardiography (PCG)
Normal S1 and S2 appear as spikes above the baseline on phonocardiograph paper. Absence of abnormal heart sounds as recorded by the phonocardiogram.
Usage of Phonocardiography (PCG)
Aids diagnosis of cardiac valve abnormalities, hypertrophic cardiomyopathy, and left ventricular failure. May be performed and retained for reference as part of the client's permanent record as a visual representation of the intensity and loudness of murmurs and other abnormal heart sounds. Excellent teaching tool because it allows the learner to visualize the different heart sounds.
Description of Phonocardiography (PCG)
A pictorial recording of the cardiac sounds heard on auscultation. A phonocardiogram uses microphones to transduce and amplify the sound into electrical impulses that are graphically recorded as a waveform by a high-speed recording apparatus. Generally, PCG is performed simultaneously with an electrocardiograph (ECG). S1 and S2 and any additional sounds, including S3, S4, murmurs, and clicks, are recorded. By comparing the ECG and PCG, one can locate normal and abnormal heart sounds and cardiac events and time them during the cardiac cycle. Phonocardiography with the addition of echocardiography is becoming a valuable noninvasive diagnostic tool. Newer phonocardiography technology may soon be available to noninvasively study coronary artery flow as well as estimate great vessel pressures, provide more reliable diagnosis, and stratify the severity of cardiac value dysfunction.
Professional Considerations of Phonocardiography (PCG)
Consent form NOT required.
- Obtain electrodes and alcohol.
- Clip the hair from the electrode sites before placement.
- The client is positioned supine. The electrode sites should be cleansed with alcohol and lightly scraped with the edge of an electrode before placement.
- After the heart apex and base are located with a stethoscope, a microphone is strapped (or secured with suction cups) in place over each site.
- Both an ECG and a PCG are recorded simultaneously for four complete cardiac cycles of sinus rhythm. For dysrhythmias, 7 to 10 cardiac cycles are recorded. The procedure is repeated with the client changed to upright and left-lateral oblique positions. The client may be asked to change his or her breathing patterns (that is, hold breath or perform deep inspiration and expiration).
- Remove the electrodes and the residual electrode gel.
Client and Family Teaching
- Cooperation is imperative throughout the procedure.
- Phonocardiography is noninvasive and takes about 30 minutes.
Factors That Affect Results
- Failure to obtain secure electrode placement causes an artifact in the electrocardiographic recording.
- Careful calibration is needed for the results to be diagnostic and generalizable.
- Phonocardiography with esophageal echocardiography provides a valuable permanent and comparable record of cardiac valve murmurs. The progress of the disease process can be followed using serial recordings.