Clinical Trial: Overnight Trials With Heat Stress in Autonomic Failure Patients With Supine Hypertension

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Overnight Trials to Compare the Effects of Controlled Heat Stress Versus Sham Control on Nocturnal Supine Hypertension in Autonomic Failure Patients

Brief Summary: Patients with autonomic failure are characterized by disabling orthostatic hypotension (low blood pressure on standing), and at least half of them also have high blood pressure while lying down (supine hypertension). Exposure to heat, such as in hot environments, often worsens their orthostatic hypotension. The causes of this are not fully understood. The purpose of this study is to evaluate whether applying local heat over the abdomen of patients with autonomic failure and supine hypertension during the night would decrease their nocturnal high blood pressure while lying down. This will help us better understand the mechanisms underlying this phenomenon, and may be of use in the treatment of supine hypertension.

Detailed Summary:

Primary autonomic failure is a neurodegenerative condition characterized by loss of efferent sympathetic function and severe baroreflex impairment. The clinical hallmark of autonomic failure is disabling orthostatic hypotension, but at least half of patients are also hypertensive while lying down. This supine hypertension can be severe and associated with end-organ damage and worsening of orthostatic hypotension due to increased pressure natriuresis. It also complicates the management of these patients by limiting the use of daytime pressor agents for the treatment of orthostatic hypotension. Currently, no antihypertensive drug effectively lowers BP and prevents pressure natriuresis without worsening standing BP.

It is well known that heat exposure (e.g. hot weather or a hot bath or shower) produces an acute and temporary worsening of orthostatic hypotension in autonomic failure patients. Factors that may predispose these patients to the lowering BP effects of heat stress include 1) impaired heat dissipation due to inability to sweat, 2) preserved heat-mediated skin vasodilation, and 3) blunted sympathetic hemodynamic responses to maintain BP (increases in cardiac output, heart rate, and vaso- and venoconstriction). Our preliminary results showed that 2 hours of passive heat stress lowers BP in these patients through a decrease in central volume. In this study, we will assess the efficacy and safety of passive heat stress in the treatment of nocturnal supine hypertension in autonomic failure patients. Our hypothesis is that controlled local (abdominal) passive heat stress applied during the night will lower nocturnal BP in autonomic failure patients with supine hypertension.

To test this hypothesis, we propose to compare the BP effects of passive heat applied during the night vs. a sham control in a randomized crossover st
Sponsor: Vanderbilt University Medical Center

Current Primary Outcome: Systolic blood pressure [ Time Frame: 10 pm - 8 am ]

Maximal change from baseline in systolic blood pressure during the night, measured from 10 pm to 8 am


Original Primary Outcome: Same as current

Current Secondary Outcome: Orthostatic Tolerance the following morning [ Time Frame: 10 min standing ]

Orthostatic tolerance defined as the area under the curve of standing systolic blood pressure calculated by the trapezoidal rule (upright systolic blood pressure multiplied by standing time) during a 10-minute standing test


Original Secondary Outcome: Same as current

Information By: Vanderbilt University Medical Center

Dates:
Date Received: February 1, 2017
Date Started: January 30, 2017
Date Completion: July 30, 2021
Last Updated: February 1, 2017
Last Verified: February 2017