Orthostatic hypertension: An underestimated cause of orthostatic intolerance.

Objective: To investigate the frequency and mechanism of orthostatic hypertension (OHT) in patients with orthostatic intolerance.

Methods: We retrospectively reviewed 1033 consecutive case series of orthostatic intolerance that underwent autonomic function tests including a head-up tilt test. OHT was defined as a paradoxical orthostatic increase in systolic blood pressure (BP) of at least 20 mmHg during the tilt. We collected autonomic parameters during the standardized autonomic function tests, which included the beat-to-beat derived hemodynamic parameters during the tilt table test and compared them with age and sex-matched normal controls and the orthostatic hypotension (OH) group with orthostatic symptoms.

Results: We identified 38 (3.7%) patients who showed OHT during the tilt. The increase in mean systolic BP during the tilt was 26.5 mmHg. Approximately 87% (33/38) of the OHT patients showed an increase in total peripheral resistance during the tilt. The mean increase in total peripheral resistance from a supine baseline was significantly higher in OHT patients compared to normal controls, but the OH group showed a decrease in mean total peripheral resistance during the tilt.

Conclusions: A select few patients with orthostatic dizziness can show OHT during the tilt and they have signs of increased peripheral resistance. Conclusions: OHT may be considered in the differential diagnosis of orthostatic intolerance.