Neurally Mediated Syncope患者におけるHead-uptilt試験中の経頭蓋超音波ドプラ法による血行動態の検討

抄録

While the head-up tilt test (HUT) is useful for establishing a diagnosis of neurally mediated syncope (NMS), it exposes patients to the stress of syncopal or presyncopal attacks unnecessarily. In order to find any changes that might predict the manifestation of syncopal attacks, we carried out transcranial Doppler sonography (TCD) during HUT in four patients with syncope. Changes in heart rate (HR), blood pressure (BP), mean blood flow velocity (MFV) in the middle cerebral artery and pulsatility index (PI) were estimated during the whole HUT period. HUT was positive in two patients and negative in the other two. In the two patients with positive HUT, MFV declined gradually from the beginning of HUT, showing a marked drop at the time of presyncopal symptoms. PI also increased gradually for 10 min prior to syncope and showed marked elevation at the time of syncope. After treatment, the time to syncope was prolonged, and the severity and frequency of NMS were reduced in both patients. The slopes of MFV decline and PI elevation during HUT were also reduced after treatment. The gradual MFV decline associated with gradual PI elevation may reflect the dysfunction of the cerebrovascular autonomic nervous control system which may underlie the pathogenesis of NMS. The estimation of gradual changes in MVF and PI during HUT may make it possible to predict the manifestation of syncopal or presyncopal attacks. TCD monitoring during HUT may therefore be useful for predicting syncopal attacks and protecting patients from unnecessary stress.