What Is the Phenomenon Recorded by Intracardiac Phonocardiography?

Abstract

Although it is widely believed that the intracardiac phonocardiography performed by high-fidelity micromanometer tip catheters affords accurate recording of sounds, it has never been proven whether such phenomenon represents longitudinal or transverse waves. Intra-aortic pressure and intra-aortic phonocardiogram were recorded in 3 dogs and 2 patients, using Millar catheters. One patient had a normal aortic valve and another had a metallic aortic valve prosthesis. In 3 dogs recordings were made near the aortic valve and 10 cm from it. Recordings were repeated when an artificial sound was produced by rupturing an intravascular balloon near the aortic valve. In one patient with a normal aortic valve, recordings were made from the central aorta near the aortic valve and 5.7 cm away from it. In the patient with an artificial aortic valve, similar recordings were made near the aortic valve and 17, 20, 37,40 and 57 cm from the aortic valve. The data were stored on a digital tape recorder. The pulse wave and A(2) of intracardiac phono were found to transmit at 4-10 m/s. A(2) of intra-aortic phono represents the dicrotic wave of aortic pressure, distorted and delayed by the filter used. Artificially produced sounds (rupture of balloon or artificial aortic valve) transmit at ≥ 400 m/s, and their amplitude declines exponentially as the distance from the source increases. Intracardiac phonocardiography usually represents rapid pressure changes of transverse pulse wave, traveling at 5-10 m/s and not longitudinal sound waves which travel at a speed ≥400 m/s.