Transient Orthostatic Hypertension During Head-Up Tilt Test in Young Adults: A Phenotype of Blood Pressure Variability.

Purpose: The mechanisms underlying orthostatic hypertension (OHT) remain poorly understood. The authors evaluated the cardiovascular, cerebrovascular dynamics, and autonomic response to head-up tilt test (HUTT) in young adults with symptoms of orthostatic intolerance and transient OHT.

Methods: Forty-four female subjects were included (34 ± 13 years old) and categorized in three groups after a 30-minute 70° passive HUTT: symptomatic patients with OHT (surge of systolic blood pressure ≥20 mm Hg for at least 5 minutes at any given time during HUTT), orthostatic intolerance (symptomatic patients without orthostatic blood pressure changes), and healthy asymptomatic control subjects.

Similar Cerebral Blood Flow and Autonomic Responses to Upright Tilt Test in Adult Patients With Different Hemodynamic Mechanisms Leading to Reflex Syncope.

Purpose: Although the underlying mechanisms of reflex syncope remain under debate, there is evidence that it results from decreased cardiac output related to splanchnic blood pooling or a fall in systemic vascular resistance. The aim was to evaluate the response of cerebrovascular and autonomic variables to passive orthostatic challenge in adult patients with different mechanisms leading to reflex syncope.

Methods: The study included 30 subjects (66% women, mean age 34 ± 14 years) who suffered a hemodynamic collapse during a drug-free head-up tilt test.