Kass D A, Marino P, Maughan W L, Sagawa K
Department of Internal Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Circulation. 1989 Dec;80(6):1783-94. doi: 10.1161/01.cir.80.6.1783.
The influence of extent and location of regional ischemia, baseline left ventricular systolic function, and autonomic reflexes on in situ left ventricular end-systolic pressure-volume relations (ESPVRs) during coronary occlusion were studied in 13 open-chest dogs. Circumflex or left anterior descending arteries were randomly occluded (at proximal or distal sites) for 3 minutes in reflex-blocked (n = 6, hexamethonium/vagotomy) and unblocked (n = 7) animals. Pressure-volume data were obtained by the conductance-catheter technique, with ESPVRs determined by transient inferior vena caval occlusion. Ischemic zone size was estimated for each occlusion by radiolabeled microspheres. The relative influence of each variable on ESPVR change with ischemia was determined by multiple regression analysis. As in previous studies, regional ischemia displaced ESPVRs to the right by an amount that varied directly with ischemic bed size (y = +0.48x, r = 0.76, p less than 0.001). However, in contrast to previous data, coronary occlusion also reduced the ESPVR slope (end-systolic elastance, Ees) in the majority of cases. The extent of slope change was primarily dependent on the baseline elastance (Eesbase), such that the higher the initial elastance, the larger its subsequent reduction for any amount of ischemia (delta Ees = -0.78Eesbase, r = 0.94, p less than 0.001). Active reflexes added an offset constant to this relation (+3.15 mm Hg/ml, p less than 0.001). In addition, Ees fell slightly more with larger ischemic regions. Thus, although previous studies have reported primarily rightward parallel shifts in ESPVR with regional ischemia, the present data also demonstrate that the slope of the relation is often reduced. Greater baseline elastances typical of in situ, as opposed to isolated, ventricles probably explain the differences in apparent responses.
在13只开胸犬中，研究了局部缺血的范围和部位、基线左心室收缩功能以及自主反射对冠状动脉闭塞期间原位左心室收缩末期压力-容积关系（ESPVRs）的影响。在反射阻断（n = 6，六甲铵/迷走神经切断术）和未阻断（n = 7）的动物中，随机闭塞旋支或左前降支动脉（近端或远端部位）3分钟。通过电导导管技术获取压力-容积数据，通过短暂下腔静脉闭塞确定ESPVRs。通过放射性标记微球估计每次闭塞的缺血区大小。通过多元回归分析确定每个变量对缺血时ESPVR变化的相对影响。与先前的研究一样，局部缺血使ESPVRs向右移位，移位量与缺血床大小直接相关（y = +0.48x，r = 0.76，p < 0.001）。然而，与先前的数据相反，冠状动脉闭塞在大多数情况下也降低了ESPVR斜率（收缩末期弹性，Ees）。斜率变化的程度主要取决于基线弹性（Eesbase），因此初始弹性越高，对于任何缺血量其随后的降低幅度就越大（ΔEes = -0.78Eesbase，r = 0.94，p < 0.001）。主动反射给这种关系增加了一个偏移常数（+3.15 mmHg/ml，p < 0.001）。此外，Ees随较大缺血区域下降得略多。因此，尽管先前的研究主要报道了局部缺血时ESPVR向右平行移位，但目前的数据也表明该关系的斜率经常降低。与离体心室相比，原位心室典型的更高基线弹性可能解释了明显反应的差异。
