Abstract
We propose a novel, two-degree of freedom mathematical model of mechanical vibrations of the heart that generates heart sounds in CircAdapt, a complete real-time model of the cardiovascular system. Heart sounds during rest, exercise, biventricular (BiVHF), left ventricular (LVHF) and right ventricular heart failure (RVHF) were simulated to examine model functionality in various conditions. Simulated and experimental heart sound components showed both qualitative and quantitative agreements in terms of heart sound morphology, frequency, and timing. Rate of left ventricular pressure (LV dp/dtmax) and first heart sound (S1) amplitude were proportional with exercise level. The relation of the second heart sound (S2) amplitude with exercise level was less significant. BiVHF resulted in amplitude reduction of S1. LVHF resulted in reverse splitting of S2 and an amplitude reduction of only the left-sided heart sound components, whereas RVHF resulted in a prolonged splitting of S2 and only a mild amplitude reduction of the right-sided heart sound components. In conclusion, our hemodynamics-driven mathematical model provides fast and realistic simulations of heart sounds under various conditions and may be helpful to find new indicators for diagnosis and prognosis of cardiac diseases.New & noteworthyTo the best of our knowledge, this is the first hemodynamic-based heart sound generation model embedded in a complete real-time computational model of the cardiovascular system. Simulated heart sounds are similar to experimental and clinical measurements, both quantitatively and qualitatively. Our model can be used to investigate the relationships between heart sound acoustic features and hemodynamic factors/anatomical parameters.
Highlights
Previous studies have proposed various theories about the genesis of heart sounds including sudden tension in otherwise loose valve membranes [1], sudden tension in chordae tendineae [2] and forceful striking of the valve leaflets [3]
To the best of our knowledge, this is the first hemodynamic-based heart sound generation model embedded in a complete real-time computational model of the cardiovascular system
A very influential premise about the origin of the major heart sound components was proposed by Rushmer in 1955 [4] who suggested that abrupt cessation of backward flow by each valve closure causes a vibration of the column of blood and the structures surrounding it including valve leaflets as well as the ventricular, atrial and arterial walls
Summary
Previous studies have proposed various theories about the genesis of heart sounds including sudden tension in otherwise loose valve membranes [1], sudden tension in chordae tendineae [2] and forceful striking of the valve leaflets [3]. A very influential premise about the origin of the major heart sound components was proposed by Rushmer in 1955 [4] who suggested that abrupt cessation of backward flow by each valve closure causes a vibration of the column of blood and the structures surrounding it including valve leaflets as well as the ventricular, atrial and arterial walls. Though this hypothesis on heart sound generation is still well-accepted, up till to date it has been relatively overlooked in modeling studies regarding how hemodynamic factors may contribute to heart sound genesis. We used our model to investigate the relation between hemodynamic factors and acoustic features of heart sounds in rest, during exercise and in heart failure
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