Harvard Medical School, Institute for Aging Research/Hebrew SeniorLife, Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, MA 02131, USA.
Hypertension. 2010 Nov;56(5):859-64. doi: 10.1161/HYPERTENSIONAHA.110.160002. Epub 2010 Sep 27.
Hypertension is associated with microvascular and macrovascular brain injury but its direct influence on the cerebral circulation is not fully clear. Our objective was to investigate the association of hypertension with global and regional cerebral vasoreactivity to CO(2) using continuous arterial spin labeling MRI, independent of stroke and white matter hyperintensities. Participants (n=62; mean age: 66.7±1.0 years, 55% women, 84% white, 65% hypertension, 47% stroke) underwent arterial spin labeling perfusion MRI during normal breathing, 5% CO(2) rebreathing, and hyperventilation, as well as 24-hour ambulatory blood pressure monitoring. Vasoreactivity was the slope of the regression between cerebral perfusion and end-tidal CO(2). White matter hyperintensity volumes were quantified. Nighttime dipping was calculated as the percentage decline in nighttime/daytime blood pressure. After accounting for stroke and white matter hyperintensity volume, hypertensive participants had lower global vasoreactivity (1.11±0.13 versus 0.43±0.1 mL/100 g per minute per millimeter of mercury; P=0.0012). Regionally, this was significant in the frontal, temporal, and parietal lobes. Higher mean systolic blood pressure was associated with lower vasoreactivity (decreased by 0.11 U/10-mm Hg increase in systolic blood pressure; P=0.04), but nighttime dipping was not (P=0.2). The magnitude of decrease in vasoreactivity in hypertension without stroke was comparable to the magnitude of decrease in vasoreactivity in stroke without hypertension. Hypertension has a direct negative effect on the cerebrovascular circulation independent of white matter hyperintensities and stroke that is comparable to that seen with stroke. Because lower vasoreactivity is associated with poor outcomes, studies of the impact of antihypertensive on vasoreactivity are important.
高血压与微血管和大血管脑损伤有关，但它对脑循环的直接影响尚不完全清楚。我们的目的是使用连续动脉自旋标记 MRI 研究高血压与 CO₂ 引起的全局和局部脑血管反应性之间的关系，而不考虑中风和脑白质高信号。参与者（n=62；平均年龄：66.7±1.0 岁，55%为女性，84%为白人，65%患有高血压，47%患有中风）在正常呼吸、5%CO₂再呼吸和过度通气期间接受动脉自旋标记灌注 MRI，以及 24 小时动态血压监测。血管反应性是脑灌注与呼气末 CO₂之间的回归斜率。白质高信号体积被量化。夜间血压下降幅度计算为夜间/日间血压下降的百分比。在考虑中风和脑白质高信号体积后，高血压患者的全局血管反应性较低（1.11±0.13 与 0.43±0.1 mL/100 g per minute per millimeter of mercury；P=0.0012）。局部来看，额叶、颞叶和顶叶明显。平均收缩压越高，血管反应性越低（收缩压每增加 10mmHg，血管反应性降低 0.11 U；P=0.04），但夜间血压下降幅度没有变化（P=0.2）。没有中风的高血压患者的血管反应性下降幅度与没有高血压的中风患者的血管反应性下降幅度相当。高血压对脑血管循环有直接的负面影响，独立于脑白质高信号和中风，与中风相当。由于较低的血管反应性与不良预后相关，因此研究抗高血压药物对血管反应性的影响很重要。
