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首页> 外文期刊>Ultrasound in Medicine and Biology >Transcranial Doppler studies on cerebral autoregulation suggest prolonged cerebral vasoconstriction in a subgroup of patients with orthostatic intolerance.
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Transcranial Doppler studies on cerebral autoregulation suggest prolonged cerebral vasoconstriction in a subgroup of patients with orthostatic intolerance.

机译：经颅多普勒对脑自动调节的研究表明，直立性不耐症患者亚组的脑血管收缩时间延长。

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We studied the cerebral autoregulation in a subgroup of patients with orthostatic intolerance, who exhibited excessively decreased middle cerebral artery flow velocity (MCAFV) on transcranial Doppler sonography (TCD) during head-up tilt (HUT) test but without orthostatic hypotension or postural tachycardia. Twenty patients and 20 age- and sex-matched controls underwent Valsalva maneuver (VM) and HUT test with simultaneous monitoring of MCAFV by TCD and blood pressure, heart rate recordings. The pulsatility index (PI), cerebrovascular resistance (CVR) and autoregulatory indices were calculated. During HUT, patients had marked MCAFV reduction (-29.0 +/- 5.25% vs. -8.01 +/- 4.37%), paradoxically decreased PI (0.68 +/- 0.17 vs. 0.96 +/- 0.28) but increased CVR (45.7 +/- 16.7% vs. 14.3 +/- 12.6%). The MCAFV decreased similarly during early phase II of VM in both groups but did not recover to baseline in patients during late phase II, phase III and less overshoot in phase IV (-11 +/- 16.7% vs. +2.2 +/- 17.9 %; -15.4 +/- 16.5% vs. -2.4 +/- 17.8% and 16.7 +/- 22.9% vs. 38.7 +/- 26.5%, respectively). We concluded that in these patients, cerebrovascular vasoconstriction in response to physiologic stimulation was normal but relaxation during and after stimulation were impaired, indicating prolonged cerebral vasoconstriction.
机译：我们研究了在体位不耐受的亚组患者中的脑自动调节功能，这些患者在抬头倾斜（HUT）试验中经颅多普勒超声（TCD）表现出大脑中动脉血流速度（MCAFV）过度降低，但没有体位性低血压或体位性心动过速。 20名患者和20名年龄和性别匹配的对照接受了Valsalva操纵（VM）和HUT测试，同时通过TCD监测MCAFV和血压，心率记录。计算搏动指数（PI），脑血管阻力（CVR）和自动调节指数。在HUT期间，患者的MCAFV显着降低（-29.0 +/- 5.25％vs. -8.01 +/- 4.37％），PI降低（0.68 +/- 0.17 vs.0.96 +/- 0.28），但CVR升高（45.7 + /-16.7％与14.3 +/- 12.6％）。两组在VM早期II期中MCAFV的下降情况相似，但在II期晚期，III期患者中未恢复至基线，IV期的过冲较少（-11 +/- 16.7％vs. +2.2 +/- 17.9） ％;-15.4 +/- 16.5％与-2.4 +/- 17.8％和16.7 +/- 22.9％与38.7 +/- 26.5％）。我们得出的结论是，在这些患者中，响应生理刺激的脑血管收缩是正常的，但刺激期间和之后的放松受到损害，表明脑血管收缩时间延长。

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