Hypotension Unawareness in Profound Orthostatic Hypotension

Background

Clinicians depend on history given by the patients when considering the diagnosis of orthostatic hypotension.

Methods

Patients with a decrease in systolic blood pressure more than 60 mm Hg from baseline during a head-up tilt table test were included. They were classified according to their symptoms during the head-up tilt table test. Localization of the cause of orthostatic hypotension was sought in each of these groups.

Results

Eighty-eight (43%) patients had typical symptoms, 49 (24%) had atypical symptoms, and 68 (33%) were asymptomatic. The average decrease in systolic blood pressure was 88 mm Hg, 87.5 mm Hg, and 89.8 mm Hg in the typical, atypical, and asymptomatic groups, respectively (P = .81). Patients reported severe dizziness with a similar frequency as lower extremity discomfort. Backache and headache also were common atypical complaints. Patients with peripheral cause of dysautonomia were able to sustain the longest upright position during the head-up tilt table test (21 minutes, compared with central dysautonomia [15 minutes]) (P = .005). There was no correlation between the cause of dysautonomia and the occurrence of symptoms during the head-up tilt table test (P = .58).

Conclusion

A third of the patients with severe orthostatic hypotension are completely asymptomatic during the head-up tilt table test, and another quarter have atypical complaints that would not lead physicians toward the diagnosis of orthostatic hypotension. These findings suggest that they might not provide adequate information in diagnosing profound orthostatic hypotension in a subset of patients with this disorder.     

起搏后体位性低血压

观察7条狗起搏前后从卧位变为站位时的血流动力学变化。起搏后起立时平均动脉压平均下降28％,是正常时(13％)的二倍,并且恢复时间明显延长(P<0.01)。实验表明起搏前后狗的体位性低血压代偿机制不同,正常时起立时心输出量增加20％左右,心率平均增加24％,而每搏输出量在开始阶段常减少,有的在整个站立过程中减少。心率在提高心输出量,代偿体位性低血压中起着重要作用。起搏后由于心率固定不变,因而出现明显的体位性低血压。提高起搏频率可改善体位性低血压。     

直立性低血压的最新研究进展

直立性低血压的发病率随着年龄增长而逐渐增加,资料显示其可增加患者脑卒中、心肌梗死及死亡等临床事件的发生。现对直立性低血压的发病机制和诊断治疗的研究进展做一综述。     

An Unusual Cause of Dyspnea

Background. Right-sided arcus aorta (RSAA) is a rare condition and usually asymptomatic. However, it may be symptomatic if it causes tracheal or esophageal compression. Methods. The authors evaluated clinical and radiological features of seven patients with RSAA who had the diagnosis between May 2006 and May 2009. Results. The authors found that the incidence of RSAA was 0.16% in patients who had applied to their clinic. The age of patients ranged from 17 to 55 years. The male to female ratio was 6/1. Four patients were symptomatic due to RSAA. Most common symptoms were dyspnea during exercise, which is similar to exercise-induced asthma and dysphagia. Two patients were misdiagnosed as asthma. The flow-volume curves on spirometry of the patients showed intrathoracic upper airway obstruction. Thorax magnetic resonance imaging (MRI) revealed marked narrowing of the tracheal air column due to external compression of RSAA in three patients. Conclusions. RSAA should be included in the differential diagnosis of asthma. Spirometry may help to suspect RSAA. Thorax computed tomography (CT) and/or MRI are the best imaging methods for the diagnosis of RSAA.