High-resolution sonomicrometry in sheep showed LV transverse diameter shortens and longitudinal diameter increases during isovolumic contraction, challenging classic cardiac cycle definitions.
Left ventricular (LV) longitudinal and transverse geometric changes during isovolumic contraction and relaxation are still controversial. This confusion is compounded by traditional definitions of these phases of the cardiac cycle. High-resolution sonomicrometry studies might clarify these issues. Crystals were implanted in six sheep at the LV apex, fibrous trigones, lateral and posterior mitral annulus, base of the aortic right coronary sinus, anterior and septal endocardial wall, papillary muscle tips, and edge of the anterior and posterior mitral leaflets. Changes in distances were time related to LV and aortic pressures and to mitral valve opening. At the beginning of isovolumic contraction, while the mitral valve was still open, the LV endocardial transverse diameter started to shorten while the endocardial longitudinal diameter increased. During isovolumic relaxation, while the mitral valve was closed, LV transverse diameter started to increase while the longitudinal diameter continued to decrease. These findings are inconsistent with the classic definitions of the phases of the cardiac cycle.
Goetz et al. (Sat,) reported a other. High-resolution sonomicrometry was evaluated on Left ventricular longitudinal and transverse geometric changes. High-resolution sonomicrometry in sheep showed LV transverse diameter shortens and longitudinal diameter increases during isovolumic contraction, challenging classic cardiac cycle definitions.