LEFT VENTRICLE MECHANICS AND HEART SOUND DURING ISOVOLUMETRIC CONTRACTION.

The authors propose a phenomenological theory of the isovolumetric contraction part ICP of the heart cycle including propagation of the depolarization wave, fiber shortening, appearance of the left ventricular pressure (LVP), and oscillation of the thick left ventricular wall (LVW) accompanied by sound radiation. They derive exact analytical solutions showing the explicit dependence on all the parameters involved. It is found that the LV pressure is predominantly determined by the spherically symmetric motion of the LVW, while the heart sounds are connected with the angle-dependent motion of the LVW.