THE HYPERTENSION OF AUTONOMIC FAILURE AND ITS TREATMENT

We studied the incidence and severity of supine hypertension in 117 pa tients with severe primary autonomic failure presenting to a referral center over a g-year period. Patients were uniformly characterized by disabling orthostatic hypotension, lack of compensatory heart rate inc rease, abnormal autonomic function tests, and unresponsive plasma nore pinephrine. Fifty-four patients had isolated autonomic impairment (pur e autonomic failure). Sixty-three patients had central nervous system involvement in addition to autonomic impairment (multiple-system atrop hy). Patients were studied off medications, in a metabolic ward, and o n a controlled diet containing 150 mEq of sodium. Fifty-six percent of patients had supine diastolic blood pressure greater than or equal to 90 mm Hg. The prevalence of hypertension was slightly greater in fema les (63%) than in males (52%). Potential mechanisms responsible for th is hypertension were investigated. No correlation was found between bl ood volume and blood pressure. Similarly, plasma norepinephrine (92+/- 15 pg/mL) and plasma renin activity (0.3+/-0.05 ng/mL per hour) were v ery low in the subset of patients with pure autonomic failure and supi ne hypertension (mean systolic/diastolic pressure, 177+/-6/108+/-2 mm Hg, range 167/97 to 219/121). Supine hypertension represents a challen ge in the treatment of orthostatic hypotension. We found these patient s to be particularly responsive to the hypotensive effects of transder mal nitroglycerin. Doses ranging from 0.025 to 0.1 mg/h decreased syst olic blood pressure by 36+/-7 mm Hg and may effectively treat supine h ypertension overnight, but the dose should be individualized and used with caution.