Stichting CardioZorg, Planetenweg 5, 2132 HN, Hoofddorp, Netherlands.
Department of Paediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
J Transl Med. 2021 May 4;19(1):193. doi: 10.1186/s12967-021-02819-0.
Orthostatic intolerance (OI) is a frequent finding in individuals with myalgic encephalomyelitis /chronic fatigue syndrome (ME/CFS). Published studies have proposed that deconditioning is an important pathophysiological mechanism in various forms of OI, including postural orthostatic tachycardia syndrome (POTS), however conflicting opinions exist. Deconditioning can be classified objectively using the predicted peak oxygen consumption (VO) values from cardiopulmonary exercise testing (CPET). Therefore, if deconditioning is an important contributor to OI symptomatology, one would expect a relation between the degree of reduction in peak VOduring CPET and the degree of reduction in CBF during head-up tilt testing (HUT).
In 22 healthy controls and 199 ME/CFS patients were included. Deconditioning was classified by the CPET response as follows: %peak VO ≥ 85% = no deconditioning, %peak VO 65-85% = mild deconditioning, and %peak VO < 65% = severe deconditioning. HC had higher oxygen consumption at the ventilatory threshold and at peak exercise as compared to ME/CFS patients (p ranging between 0.001 and < 0.0001). Although ME/CFS patients had significantly greater CBF reduction than HC (p < 0.0001), there were no differences in CBF reduction among ME/CFS patients with no, mild, or severe deconditioning. We classified the hemodynamic response to HUT into three categories: those with a normal heart rate and blood pressure response, postural orthostatic tachycardia syndrome, or orthostatic hypotension. No difference in the degree of CBF reduction was shown in those three groups.
This study shows that in ME/CFS patients orthostatic intolerance is not caused by deconditioning as defined on cardiopulmonary exercise testing. An abnormal high decline in cerebral blood flow during orthostatic stress was present in all ME/CFS patients regardless of their %peak VO results on cardiopulmonary exercise testing.
直立不耐受（OI）是肌痛性脑脊髓炎/慢性疲劳综合征（ME/CFS）患者常见的发现。已发表的研究提出，去适应是各种形式 OI 的重要病理生理机制，包括体位性心动过速综合征（POTS），但存在相互矛盾的观点。去适应可以使用心肺运动测试（CPET）中预测的峰值摄氧量（VO）值进行客观分类。因此，如果去适应是 OI 症状的重要原因之一，那么人们会期望 CPET 中峰值 VO 的降低程度与头高位倾斜测试（HUT）中 CBF 的降低程度之间存在关系。
共纳入 22 名健康对照者和 199 名 ME/CFS 患者。根据 CPET 反应将去适应分类如下：%peak VO≥85%=无去适应，%peak VO 65-85%=轻度去适应，%peak VO<65%=严重去适应。与 ME/CFS 患者相比，HC 在通气阈值和峰值运动时的耗氧量更高（p 值介于 0.001 和<0.0001 之间）。尽管 ME/CFS 患者的 CBF 降低幅度明显大于 HC（p<0.0001），但无、轻度或重度去适应的 ME/CFS 患者之间的 CBF 降低幅度没有差异。我们将 HUT 的血液动力学反应分为三类：心率和血压反应正常、体位性心动过速综合征或直立性低血压。三组患者的 CBF 降低幅度无差异。
本研究表明，在 ME/CFS 患者中，直立不耐受不是由心肺运动测试定义的去适应引起的。在所有 ME/CFS 患者中，无论其 CPET 中%peak VO 的结果如何，在直立应激期间都会出现大脑血液流量异常急剧下降。
