Nonuniformity and volume loading independently influence isovolumic relaxation rates.
Nonuniformity and volume loading independently influence isovolumic relaxation rates.
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不均匀性和体积负荷独立影响等容松弛率。
DOI：
10.1152/ajpheart.1989.257.6.h1927
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Lew,WY
中科院分区：
文献类型：
--
作者：
Gillebert,TC;Lew,WY
在7只麻醉犬上，观察负荷条件和左心室功能不均匀对左心室压下降速率的影响。通过闭塞下腔静脉和/或静脉输注右旋糖酐改变负荷条件。将8-20 ng异丙肾上腺素注入轻度左前降支，造成冠状动脉前壁不同步、早起的节段延长。通过比较前壁和后壁的节段长度，用中壁声学测微仪测量，量化时间和区域的不一致性指数。用峰值-dp/dt、时间常数tau和等容松弛时间来评价左室压下降的速度。在不改变非均匀指数的情况下，容量负荷降低了左心室压降速率。在不改变整体负荷条件的情况下，冠脉内异丙肾上腺素产生不均匀，并降低左心室压下降的速率。异丙肾上腺素(恒定剂量)的作用与左心室容量无关。我们的结论是，在完整的射血左心室中，负荷条件和不均匀是决定左室压下降速率的重要因素，但这两个因素是通过在很大程度上独立的机制发挥作用的。
We examined the influence of loading conditions and nonuniformity of left ventricular (LV) function on the rate of LV pressure fall in seven anesthetized dogs. Loading conditions were altered with vena cavae occlusions and/or intravenous infusions of dextran. Nonuniformity was produced by injecting 8-20 ng of isoproterenol into the mild left anterior descending coronary artery to produce an asynchronous and early onset of segment lengthening in the anterior wall. Temporal and regional nonuniformity were quantified with indexes derived by comparing segment lengths in the anterior and posterior walls, measured with midwall sonomicrometers. The rate of LV pressure fall was assessed with peak -dP/dt, the time constant, tau, and the duration of isovolumic relaxation. Volume loading decreased the rate of LV pressure fall without altering the nonuniformity indexes. Intracoronary isoproterenol produced nonuniformity and decreased the rate of LV pressure fall without altering global loading conditions. The effects of isoproterenol (in a constant dose) were similar irrespective of the LV volume. We conclude that in the intact, ejecting left ventricle, loading conditions and nonuniformity are important determinants of the rate of LV pressure fall, but these two factors exert their influence by mechanisms that are largely independent.