Time-frequency analysis of the first heart sound

Quantitative phonocardiography has been limited by many factors: nonstandard nomenclature and recording techniques, complicated mechanoacoustic generation, propagation and coupling, and inherent heart sound nonstationarity. New nonstationary signal processing techniques provide a powerful tool for phonocardiography, particularly in regard to the first heart sound. Recent work supports the concept that the first heart sound is composed of valve-initiated myocardial traveling waves superimposed upon the acceleration of myocardial contraction. Clinically, nonstationary signal analysis has been most frequently applied toward the study of mechanical prosthetic valves. However, a better understanding of first heart sound mechanics may facilitate the diagnosis of myocardial and native-valve pathology. Given the inherent system complexity, an interdisciplinary approach incorporating physicians, mechanical engineers, seismologists, and electrical engineers is imperative.>