What is Orthostatic Hypotension
Orthostatic hypotension is an abnormal drop in blood pressure upon standing—specifically a decrease in systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mmHg within 3 minutes of standing from a supine or seated position. 1
Definition and Diagnostic Criteria
The European Society of Cardiology defines orthostatic hypotension as a progressive and sustained fall in systolic BP from baseline value ≥20 mmHg or diastolic BP ≥10 mmHg, or a decrease in systolic BP to <90 mmHg, occurring within 3 minutes of active standing or head-up tilt of at least 60 degrees. 1
In patients with supine hypertension, a systolic BP drop of ≥30 mmHg should be considered diagnostic. 2
The condition may be symptomatic or asymptomatic—patients do not need to experience symptoms for the diagnosis to be clinically significant. 3, 4
Clinical Subtypes Based on Timing
Orthostatic hypotension is classified into distinct subtypes based on when the blood pressure drop occurs:
Initial orthostatic hypotension occurs within 15 seconds of standing, with a BP decrease >40 mmHg systolic and/or >20 mmHg diastolic, followed by spontaneous rapid recovery within 40 seconds. 1
Classical orthostatic hypotension develops within 30 seconds to 3 minutes of standing and represents sustained hypotension due to impaired vasoconstriction. 1
Delayed orthostatic hypotension occurs beyond 3 minutes of standing and is characterized by a slow progressive decrease in BP. 1
Pathophysiology
The fundamental problem in orthostatic hypotension is failure of peripheral vascular resistance to increase appropriately upon standing, not primarily a cardiac pump failure, though cardiac dysfunction can contribute. 5
In neurogenic orthostatic hypotension, cardiovascular sympathetic fibers fail to increase total peripheral vascular resistance upon standing, resulting in inadequate vasoconstriction and a blunted heart rate response (usually <10 beats per minute increase). 5, 1
In non-neurogenic orthostatic hypotension (such as from hypovolemia), the heart rate response is preserved or enhanced (>10 beats per minute increase). 5, 1
Upon standing, approximately 500-800 mL of blood pools in the lower extremities and splanchnic circulation; normally, the autonomic nervous system compensates by constricting veins and arteries while increasing heart rate and cardiac contractility. 6
Common Symptoms
When symptomatic, patients experience manifestations of cerebral and systemic hypoperfusion:
Most common symptoms: Dizziness, lightheadedness, pre-syncope, weakness, fatigue, and visual disturbances (blurring, enhanced brightness, tunnel vision). 1, 4
Cardiovascular symptoms: Palpitations, chest pain, and dyspnea. 1, 4
Characteristic pain pattern: Neck pain in the occipital/paracervical and shoulder region (coat hanger syndrome), low back pain, or precordial pain. 1, 4
Other manifestations: Hearing disturbances (impaired hearing, crackles, tinnitus), nausea, sweating, and syncope. 1, 3
Major Causes
Medication-Induced (Most Common)
Diuretics cause volume depletion and are among the most common culprits in medication-induced orthostatic hypotension. 5
Vasodilators (including nitrates) directly reduce vascular tone. 5
Alpha-adrenergic blockers impair vasoconstriction and are particularly problematic in initial orthostatic hypotension. 5
Dopamine agonists (such as ropinirole) cause orthostatic hypotension through D2-mediated blunting of the noradrenergic response to standing and subsequent decrease in peripheral vascular resistance. 7
Autonomic Nervous System Dysfunction
Primary autonomic failure: Multiple system atrophy, pure autonomic failure, Parkinson's disease, and dementia with Lewy bodies. 5
Secondary autonomic failure: Diabetes mellitus with autonomic neuropathy, amyloidosis with autonomic nerve infiltration, spinal cord injuries, and autoimmune/paraneoplastic autonomic neuropathy. 5
Volume Depletion and Other Causes
Severe volume depletion from excessive diuresis, dehydration, or blood loss causes non-neurogenic orthostatic hypotension. 5, 6
Age-related physiologic changes including stiffer hearts less responsive to preload changes, impaired compensatory vasoconstrictor reflexes, baroreflex dysfunction, and reduced cerebral autoregulation. 5
Clinical Significance and Epidemiology
Prevalence ranges from 5% in middle-aged adults to 20% in community-dwelling elderly, and up to 33% in elderly hospital inpatients. 5, 4
Orthostatic hypotension accounts for 20-30% of syncope cases in older adults. 5
The condition is associated with a 64% increase in age-adjusted mortality, markedly increased cardiovascular morbidity, and up to a 50% increase in relative risk of all-cause mortality. 5, 4
Orthostatic hypotension significantly increases the risk of falls, especially backward falls in elderly patients. 5, 4
Diagnostic Testing
Measure BP after 5 minutes of lying or sitting, then at 1 minute and 3 minutes after standing. 5, 4
If the patient cannot stand safely or clinical suspicion remains high despite normal bedside testing, head-up tilt table testing at 60 degrees or more is recommended. 1, 4
Assessment of heart rate response helps distinguish neurogenic (blunted increase) from non-neurogenic (preserved or enhanced increase) causes. 1, 5