Evidence of incomplete left ventricular relaxation in the dog: prediction from the time constant for isovolumic pressure fall.
Evidence of incomplete left ventricular relaxation in the dog: prediction from the time constant for isovolumic pressure fall.
复制标题
狗左心室不完全舒张的证据：根据等容压下降的时间常数进行预测。
DOI：
10.1172/jci109250
复制
发表时间：
1978
期刊：
影响因子：
--
通讯作者：
J. Weiss
中科院分区：
文献类型：
--
作者：
M. Weisfeldt;J. Frederiksen;F. Yin;J. Weiss
尽管有人提出不完全舒张解释了左心室舒张末压相对于容量的某些增加，但还没有明确的证据表明不完全舒张发生在完整的工作心室中。为了识别不完全舒张，对 10 只犬右心旁路手术准备过程中心室起搏期间的左心室压力-尺寸关系进行了研究。首先根据起搏中断后延长舒张期结束时的压力和尺寸值确定每个心室的完全放松的指数舒张压尺寸线。对于在广泛变化的血流动力学条件下起搏期间的 167 次心跳，舒张压维度值遇到这条定义充盈期间完全放松状态的线，表明舒张在舒张末期之前完成。确定所有心跳的等容指数压降 (T) 的时间常数。对于该指数函数，如果没有发生舒张期充盈，则在最大负 dP/dt 后 3.5 T 时将完成 97% 的压力下降。对于 167 次心跳，完全放松的压力维度线总是在 3.5 T 之前遇到。在非常快的起搏速率（170-200 次/分钟）和（或）药物延长放松的情况下，会发生不完全放松，这一点可以通过在舒张期间从未达到定义完全放松状态的线这一事实来证明 (n = 15)。这种不完全放松的证据仅在随后的搏动在 3.5 T 之前开始时发生，但在这些条件下并不总是发生。因此，舒张末期压力相对于舒张容积的增加可能是由于在心率足够快或心室舒张时间足够长的情况下不完全舒张造成的。当下一次心跳在最大负 dP/dt 之后超过 3.5 T 开始时，不会发生不完全松弛。
Although it has been proposed that incomplete relaxation explains certain increases in left ventricular end diastolic pressure relative to volume, there has been no clear demonstration that incomplete relaxation occurs in the intact working ventricle. To identify incomplete relaxation, left ventricular pressure-dimension relationships were studied in 10 canine right heart bypass preparations during ventricular pacing. The fully relaxed, exponential diastolic pressure-dimension line for each ventricle was first determined from pressure and dimension values at the end of prolonged diastoles after interruption of pacing. For 167 beats during pacing under widely varying hemodynamic conditions, diastolic pressure-dimension values encountered this line defining the fully relaxed state during the filling period indicating that relaxation was complete before end diastole. The time constant for isovolumic exponential pressure fall (T) was determined for all beats. For this exponential function, if no diastolic filling occurred, 97% of pressure fall would be complete by 3.5 T after maximal negative dP/dt. For the 167 beats the fully relaxed pressure-dimension line was always encountered before 3.5 T. With very rapid pacing rates (170-200 beats/min) and(or) with pharmacologic prolongation of relaxation, incomplete relaxation occurred as evidenced by the fact that the line defining the fully relaxed state was never reached during diastole (n = 15). This evidence of incomplete relaxation occurred only when the subsequent beat began before 3.5 T but did not always occur under these conditions. Thus, an increase in end diastolic pressure relative to diastolic volume may result from incomplete relaxation under conditions of sufficiently rapid heart rate or sufficiently prolonged ventricular relaxation. Incomplete relaxation does not occur when the next beat begins more than 3.5 T after maximum negative dP/dt.