Disorders In Depth
Baroreflex Failure
Introduction
Baroreflex failure, a rare disorder due to a damaged baroreflex arc, prevents the body’s buffering of high and low blood pressures. It is characterized by marked lability of BP with episodic severe hypertension and increased heart rate during stress and hypotension and normal or reduced heart rate during rest. There is often also headache, diaphoresis, emotional lability, and refractoriness of heart rate in response to exogenous vasoactive substances. It may resemble another rare disorder, pheochromocytoma, a catecholamine-secreting tumor.
Etiologies may include:
- Surgery and irradiation for cancer of the throat
- Injury to the glossopharyngeal and vagus nerves
- Cell loss bilaterally in the nuclei of the solitary tract in the setting of a degenerative neurologic disease of medullary and higher structures.
- For many of those who suffer from baroreflex failure, an etiology remains unknown.
Symptoms
- Baroreflex failure has a range of presentations, varying from the acute onset of a hypertensive crisis to a chronically volatile blood pressure and heart rate with hypertensive surges in response to stress, punctuated by periods of normal or even low blood pressure during rest. Differentiating this syndrome from other causes of labile hypertension is essential in devising effective treatment.
- Patients with baroreflex failure may present with severe hypertension, either sustained or episodic. Blood pressures can reach 170-320/110-135.
- Accompanying tachycardia may suggest the diagnosis of pheochromocytoma, which is supported by sensations of warmth and or flushing, palpitations, and headache.
Management
- Clonidine or methyldopa suppresses pressor and tachycardic surges
- Diazepam reduces stress
