title: Reinvestigation of the relationship between the amplitude of the first heart sound to cardiac dynamics.
abstract: The relationships between the amplitude of the first heart sound (S1) and the rising rate of left ventricular pressure (LVP) concluded in previous studies were not consistent. Some researchers believed the relationship was positively linear; others stated the relationship was only positively correlated. To further investigate this relationship, this study simultaneously sampled the external phonocardiogram, electrocardiogram, and intracardiac pressure in the left ventricle in three anesthetized dogs, while invoking wide hemodynamic changes using various doses of epinephrine. The relationship between the maximum amplitude of S1 and the maximum rising rate of LVP and the relationship between the amplitude of dominant peaks/valleys and the corresponding rising rate of LVP were examined by linear, quadratic, cubic, and exponential models. The results showed that the relationships are best fit by nonlinear exponential models.
authors.affiliation: Department of Biomedical Engineering, Dalian University of Technology Dalian, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Tang
authors.forename: Chengjie
authors.initials: C
authors.lastname: Ruan
authors.forename: Tianshuang
authors.initials: T
authors.lastname: Qiu
authors.forename: Yongwan
authors.initials: Y
authors.lastname: Park
authors.forename: Shouzhong
authors.initials: S
authors.lastname: Xiao
keywords: Amplitude of the first heart sound; exponential model; model fitting; rise rate of left ventricular pressure