Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1065, USA.
Brain Res. 2012 Oct 5;1477:83-91. doi: 10.1016/j.brainres.2012.08.024. Epub 2012 Aug 29.
Arterial hypertension is a major risk factor for ischemic stroke. However, the management of preexisting hypertension is still controversial in the treatment of acute stroke in hypertensive patients. The present study evaluates the influence of preserving hypertension during focal cerebral ischemia on stroke outcome in a rat model of chronic hypertension, the spontaneously hypertensive rats (SHR). Focal cerebral ischemia was induced by transient (1h) occlusion of the middle cerebral artery, during which mean arterial blood pressure was maintained at normotension (110-120mm Hg, group 1, n=6) or hypertension (160-170mm Hg, group 2, n=6) using phenylephrine. T2-, diffusion- and perfusion-weighted MRI were performed serially at five different time points: before and during ischemia, and at 1, 4 and 7 days after ischemia. Lesion volume and brain edema were estimated from apparent diffusion coefficient maps and T2-weighted images. Regional cerebral blood flow (rCBF) was measured within and outside the perfusion deficient lesion and in the corresponding regions of the contralesional hemisphere. Neurological deficits were evaluated after reperfusion. Infarct volume, edema, and neurological deficits were significantly reduced in group 2 vs. group 1. In addition, higher values and rapid restoration of rCBF were observed in group 2, while rCBF in both hemispheres was significantly decreased in group 1. Maintaining preexisting hypertension alleviates ischemic brain injury in SHR by increasing collateral circulation to the ischemic region and allowing rapid restoration of rCBF. The data suggest that maintaining preexisting hypertension is a valuable approach to managing hypertensive patients suffering from acute ischemic stroke.
动脉高血压是缺血性中风的一个主要危险因素。然而，在高血压患者急性中风的治疗中，对于预先存在的高血压的管理仍然存在争议。本研究评估了在慢性高血压大鼠模型（自发性高血压大鼠）中，在局灶性脑缺血期间维持高血压对中风结果的影响。通过短暂（1 小时）阻断大脑中动脉来诱导局灶性脑缺血，在此期间使用苯肾上腺素将平均动脉血压维持在正常血压（110-120mmHg，第 1 组，n=6）或高血压（160-170mmHg，第 2 组，n=6）。在五个不同的时间点进行 T2-、弥散和灌注加权 MRI 序列：在缺血前和缺血期间，以及在缺血后 1、4 和 7 天。通过表观弥散系数图和 T2 加权图像来估计病变体积和脑水肿。在灌注不足的病变内和外部以及对侧半球的相应区域测量局部脑血流（rCBF）。在再灌注后评估神经功能缺损。与第 1 组相比，第 2 组的梗死体积、水肿和神经功能缺损明显减少。此外，在第 2 组中观察到更高的值和 rCBF 的快速恢复，而在第 1 组中两个半球的 rCBF 均显著降低。维持预先存在的高血压通过增加对缺血区域的侧支循环并允许 rCBF 的快速恢复，从而减轻 SHR 的缺血性脑损伤。数据表明，维持预先存在的高血压是管理患有急性缺血性中风的高血压患者的一种有价值的方法。
