Hayashida K, Nishiooeda Y, Hirose Y, Ishida Y, Nishimura T
Department of Radiology, National Cardiovascular Center, Osaka, Japan.
J Nucl Med. 1996 Jan;37(1):1-4.
To clarify the relationship between abnormalities in cerebral blood flow (CBF) and in blood pressure regulation, we performed 99mTc-HMPAO brain SPECT in association with measurement of plasma norepinephrine and blood pressure in both the upright and supine positions.
We studied six patients with orthostatic hypotension and six normal patients. No patient had any significant stenosis of the carotid arteries on echocardiography-Doppler ultrasound and no abnormalities on brain MRI or CT. Changes in systolic blood pressure were monitored during the upright test, and 8-ml blood samples were taken at baseline and at 1 and 5 min after the upright position.
Systolic blood pressure decreased by a mean of 38 +/- 10 and 9 +/- 3 mmHg in the orthostatic hypotension and normal groups, respectively. Compared with baseline values, plasma norepinephrine levels at 1 and 5 min after the upright test did not increase in the orthostatic hypotension group but did increase significantly in the normal group. In the orthostatic hypotension group, 99mTc-HMPAO brain SPECT showed postural cerebral hypoperfusion in the bilateral frontal areas, of which the mean count ratio of the frontal-to-cerebellar area between the upright and supine positions significantly changed from 0.871 +/- 0.029 to 0.942 +/- 0.067 and from 0.881 +/- 0.035 to 0.954 +/- 0.073 in the right and left areas, respectively. No postural change in CBF was evident in other areas in the orthostatic hypotension group. In the normal group, there were no such changes in CBF, blood pressure and plasma norepinephrine levels during the upright test.
Postural cerebral hypoperfusion in the frontal areas in the orthostatic hypotension group might relate to maladaptation of the vascular response during the upright test.
为阐明脑血流量（CBF）异常与血压调节异常之间的关系，我们进行了99mTc-HMPAO脑单光子发射计算机断层扫描（SPECT），并同时测量了立位和卧位时的血浆去甲肾上腺素及血压。
我们研究了6例直立性低血压患者和6例正常患者。所有患者经超声心动图-多普勒超声检查均无明显颈动脉狭窄，脑磁共振成像（MRI）或计算机断层扫描（CT）均无异常。在直立试验过程中监测收缩压变化，并在基线、直立位后1分钟和5分钟采集8毫升血样。
直立性低血压组和正常组的收缩压平均分别下降38±10 mmHg和9±3 mmHg。与基线值相比，直立试验后1分钟和5分钟时，直立性低血压组的血浆去甲肾上腺素水平未升高，而正常组显著升高。在直立性低血压组中，99mTc-HMPAO脑SPECT显示双侧额叶出现姿势性脑灌注不足，直立位与卧位之间额叶与小脑区域的平均计数比在右侧和左侧区域分别从0.871±0.029显著变为0.942±0.067，从0.881±0.035显著变为0.954±0.073。直立性低血压组其他区域未发现CBF的姿势性变化。在正常组中，直立试验期间CBF、血压和血浆去甲肾上腺素水平均无此类变化。
直立性低血压组额叶的姿势性脑灌注不足可能与直立试验期间血管反应的适应不良有关。
