Design and Test of a PCG-ECG Synchronous Auscultation System

Heart sound auscultation is the most important technique physicians use to examine cardiovascular diseases. Doctors use their clinical experience combined with listening to the patient’s first heart sound (S1), second heart sound (S2), and heart murmurs during auscultation to conduct preliminary screening for cardiovascular diseases. However, doctors with insufficient clinical experience in auscultating heart sounds [phonocardiogram (PCG)] find it challenging to accurately identify the characteristic signals in the aforementioned heart sound signals. The onset of the first heart sound in heart sound signals corresponds to the peak of the R wave in the electrocardiogram (ECG) signal, and the onset of the second heart sound corresponds to the T wave. Therefore, by combining the timing relationship between the two, doctors can effectively identify the characteristics of heart sound signals, thus improving the accuracy of screening for cardiovascular diseases. This article presents the design of an auscultation system capable of simultaneously measuring both PCG signals and ECG signals while adhering to medical electrical safety standards and medical electromagnetic compatibility (EMC) standards. The designed synchronous auscultation system successfully passed rigorous testing for compliance with both medical electrical safety and medical EMC standards. This testing validated the system’s security and stability. The system noise in the ECG channel was less than <inline-formula> <tex-math notation="LaTeX">$30~\mu $ </tex-math></inline-formula>V and the frequency response ranged from 0.05 to 100 Hz, while the signal-to-noise ratio in the system’s heart sound channel was 25.6 dB. Thus, the system’s accuracy was confirmed. The system test of the PCG-ECG synchronous auscultation system demonstrated that the P-QRS-T waveform of the ECG signal was distinctly visible, and the waveforms of the first heart sound (S1) and second heart sound (S2) of the heart sound signal were crisp and intact.