Local Heat Therapy for Hypertension in Autonomic Failure

Nashville, TN: Patients with autonomic failure and supine hypertension when treated with local heat therapy showed an effective lowering of overnight blood pressure (BP), according to a recent study in the Journal of the American Heart Association. The findings imply that local heat application can be a novel approach for the treatment of nocturnal supine hypertension.

"Long-term safety and efficacy of this treatment in improving nighttime fluid loss and daytime orthostatic hypotension needs to be assessed in the future trials," wrote the authors.

Majority of patients with autonomic failure are affected by supine hypertension which can worsen daytime orthostatic hypotension by inducing pressure diuresis and volume loss during the night and is associated with end-organ damage. In healthy people exposed to heat, sympathetic activation can prevent BP from falling. Considering this, Luis E. Okamoto, Vanderbilt University Medical Center, Nashville, TN, and colleagues hypothesized that passive heat had a BP‐lowering effect in patients with autonomic failure and could be used to treat their supine hypertension.

Study Protocols

• Protocol 1: Involving 22 patients, the researcher assessed the acute effects of local heat (40–42°C applied with a heating pad placed over the abdomen for 2 hours) versus sham control in a randomized crossover fashion.
• Protocol 2: A proof‐of‐concept overnight study with 12 patients, where the researchers compared the effects of local heat (38°C applied with a water‐perfused heating pad placed under the torso from 10 PM to 6 AM) versus placebo pill.

Key Findings

• Protocol 1: Heat acutely decreased systolic BP by −19±4 mm Hg (versus 3±4 with sham, P<0.001) owing to decreases in stroke volume (−18±5% versus −4±4%) and cardiac output (−15±5% versus −2±4%).
• Protocol 2: Heat decreased nighttime systolic BP (maximal change −28±6 versus −2±6 mm Hg). BP returned to baseline by 8 am. The nocturnal systolic BP decrease correlated with a decrease in urinary volume (r=0.57) and an improvement in the morning upright systolic BP (r=−0.76).

"Local heat therapy effectively lowered overnight BP in patients with autonomic failure and supine hypertension and offers a novel approach to treat this condition," wrote the authors. "Future studies are needed to assess the long‐term safety and efficacy in improving nighttime fluid loss and daytime orthostatic hypotension."

Reference

The study titled, "Local Passive Heat for the Treatment of Hypertension in Autonomic Failure," is published in the Journal of the American Heart Association.

DOI: https://www.ahajournals.org/doi/10.1161/JAHA.120.018979