Hemodynamic mechanisms underlying orthostatic hypotension in stroke survivors: a cross-sectional study.

Background: Understanding the hemodynamic mechanisms underlying orthostatic hypotension is essential for selecting the appropriate treatment based on individual hemodynamic patterns. However, the relative contribution of changes in cardiac output and total peripheral resistance to orthostatic hypotension in stroke survivors remains unclear.

Objective: This study aimed to determine whether orthostatic hypotension is more strongly associated with a marked cardiac output decrease or an impaired total peripheral resistance increase among individuals with stroke.

Methods: In this cross-sectional study, 23 participants with stroke (13 males, mean [SD] age 63.7 [12.1] years, mean time since stroke 85.1 [34.1] days) underwent a head-up tilt test to assess orthostatic changes in blood pressure and hemodynamic variables. The head-up tilt test protocol consisted of a 5-min period in the supine position followed by a 5-min period with a 70° head-up tilt. Orthostatic hypotension was defined as a reduction in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg during the test. Heart rate, stroke index, cardiac index, and total peripheral resistance index were measured as hemodynamic variables.

Results: Orthostatic hypotension was identified in five participants (22%). These individuals demonstrated significantly greater orthostatic cardiac index increases (F_(5,105) = 2.75, p = 0.023, partial η² = 0.126) and more pronounced orthostatic total peripheral resistance index decreases (F_(5,105) = 4.19, p = 0.002, partial η² = 0.166) than those without orthostatic hypotension.

Conclusions: Our results suggest that impaired orthostatic total peripheral resistance increase mainly contributes to orthostatic hypotension in stroke survivors.