Laster S B, Ohnishi Y, Saffitz J E, Goldstein J A
Department of Medicine, Washington University School of Medicine, St Louis, Mo. 63110.
Circulation. 1994 Sep;90(3):1398-409. doi: 10.1161/01.cir.90.3.1398.
Right ventricular free wall (RVFW) ischemia impairs global RV performance and may result in acute hemodynamic compromise. However, RV function and hemodynamic performance typically improve spontaneously over time. This study was designed to determine whether reperfusion facilitates recovery of function in the ischemic right ventricle.
Closed chest dogs underwent right coronary balloon occlusion for 1 hour (n = 9), 4 hours (n = 6), or 8 hours (n = 7). In all animals, occlusion depressed RVFW function and global RV performance. After 1 hour of ischemia, reperfusion led to immediate improvement in RVFW function and consequently global RV performance, with complete recovery over 4 weeks and scar in < 1% of total RVFW area. Reperfusion after 4- and 8-hour occlusions resulted in acute improvement in global RV performance but to a lesser extent and by different mechanisms, since RVFW contraction remained severely impaired. This disproportionate recovery of global RV function was attributable to diminished RVFW dyskinesis associated with reperfusion-induced increments in RVFW diastolic thickness (characterized histopathologically in 6 additional animals subjected to 4-hour occlusions but killed 1 hour after reperfusion by interstitial edema, contraction band necrosis, and hemorrhage). Although later reperfusion was associated with a slower pace and lesser extent of recovery, RVFW contraction improved markedly over time. At 4 weeks, there was trivial RVFW scar in 4-hour animals (2% of total RVFW area), and, although fibrosis was significantly greater in 8-hour animals (7% of RVFW area), infarction was minimal relative to the extent of jeopardized myocardium.
The responses of ischemic RV myocardium to reperfusion are complex, with disparate effects according to the duration of preceding ischemia. Early reperfusion results in prompt improvement in and subsequent complete recovery of RVFW contraction and global RV performance, with trivial or no RVFW scar. Late reperfusion leads to little acute recovery of RVFW function, but global performance improves owing to diminished RVFW dyskinesis associated with reperfusion-induced increments in RVFW diastolic thickness. Nevertheless, RVFW function improves over time, with minimal evidence of infarction. Therefore, reperfusion facilitates recovery of RV function and minimizes the extent of infarction even after prolonged ischemia.
右心室游离壁（RVFW）缺血会损害右心室整体功能，并可能导致急性血流动力学障碍。然而，右心室功能和血流动力学表现通常会随时间自发改善。本研究旨在确定再灌注是否有助于缺血右心室功能的恢复。
开胸犬接受右冠状动脉球囊闭塞1小时（n = 9）、4小时（n = 6）或8小时（n = 7）。在所有动物中，闭塞均会降低RVFW功能和右心室整体功能。缺血1小时后，再灌注导致RVFW功能立即改善，进而使右心室整体功能得到改善，4周内完全恢复，且RVFW总面积中瘢痕形成小于1%。4小时和8小时闭塞后再灌注导致右心室整体功能急性改善，但程度较小且机制不同，因为RVFW收缩仍严重受损。右心室整体功能这种不成比例的恢复归因于与再灌注诱导的RVFW舒张期厚度增加相关的RVFW运动障碍减轻（在另外6只接受4小时闭塞但在再灌注1小时后处死的动物中，通过组织病理学特征为间质水肿、收缩带坏死和出血）。尽管后期再灌注与恢复速度较慢和程度较小相关，但RVFW收缩随时间明显改善。4周时，4小时组动物的RVFW瘢痕轻微（占RVFW总面积的2%），虽然纤维化在梗死后8小时组动物中明显更严重（占RVFW面积的7%），但相对于受危及心肌的范围，梗死面积最小。
缺血性右心室心肌对再灌注的反应很复杂，根据先前缺血的持续时间有不同的影响。早期再灌注可使RVFW收缩和右心室整体功能迅速改善并随后完全恢复，RVFW瘢痕轻微或无。晚期再灌注导致RVFW功能几乎没有急性恢复，但由于与再灌注诱导的RVFW舒张期厚度增加相关的RVFW运动障碍减轻，整体功能得到改善。尽管如此，RVFW功能随时间改善，梗死证据极少。因此，即使在长时间缺血后，再灌注也有助于右心室功能的恢复并使梗死范围最小化。
