Isovolumic relaxation time varies predictably with its time constant and aortic and left atrial pressures: implications for the noninvasive evaluation of ventricular relaxation.

摘要: The isovolumic relaxation time (IVRT) is an important noninvasive index of left ventricular diastolic function. Despite its widespread use, however, the IVRT has not been related analytically to invasive parameters Establishing such a relationship would make more useful by itself and perhaps allow it be combined precisely with other filling. purpose this study was validate quantitative relationship. Assuming monoexponential decay pressure (pv) zero-pressure asymptote, postulated that interval from aortic valve closure (when pv = p(o)) until mitral opening atrial pressure, pA) given tau[log(p(o))-log(pA)], where tau constant log base e. To test hypothesis we analyzed data six canine experiments in which preload afterload were controlled nonpharmacologically. In addition, adjusted use beta-adrenergic blockade calcium infusion, as well hypothermia. each experiment collected before after surgical formation stenosis, performed permit wide range pressures. High-fidelity atrial, ventricular, root pressures digitized, measured dicrotic notch atrioventricular crossover point, calculated nonlinear least-squares regression.(ABSTRACT TRUNCATED AT 250 WORDS)