Spectrum of orthostatic hypotension

Baroreflexes regulate sympathetic and parasympathetic outflow to maintain BP. Classic orthostatic hypotension occurs when there is generalized autonomic failure (OH_gaf), often involving both the afferent and efferent limbs of the baroreflex. Afferent baroreflex failure occurs due to a selective lesion of the afferent limb. Initial OH (OH_ini) can occur in normal subjects, can be symptomatic and even cause syncope. With partial adrenergic failure, BP recovery after OH_ini is delayed, and patients with delayed BP recovery have increased morbidity and mortality. OH can be delayed in onset (OH_del) and occur after 3min of standing. OH_del is also associated with increased morbidity and mortality depending on the underlying etiology. OH due to partial adrenergic failure can present with sympathetic overactivity, described as hyperadrenergic OH. The management of OH begins with defining the phenotype, amount of adrenergic impairment, followed by patient education. Increasing severity requires progression from nonpharmacologic to pharmacologic measures.