What is classic Orthostatic Hypotension (OH)?

Classic Orthostatic Hypotension (OH)

Classic orthostatic hypotension (OH) is defined as a sustained decrease in systolic blood pressure ≥20 mmHg, diastolic blood pressure ≥10 mmHg, or a sustained decrease in systolic blood pressure to an absolute value <90 mmHg within 3 minutes of standing or head-up tilt of at least 60 degrees. 1

Diagnostic Criteria and Characteristics

• In patients with supine hypertension, a systolic blood pressure drop ≥30 mmHg should be considered diagnostic 1
• The blood pressure drop starts immediately upon standing and the rate of drop decreases, resulting in sustained low blood pressure that may persist for many minutes 1
• Heart rate increase is typically blunted in neurogenic OH (usually <10 beats per minute) due to impaired autonomic heart rate control 1
• In contrast, orthostatic heart rate increase is preserved or even enhanced in OH due to hypovolemia 1
• Classic OH is associated with increased mortality and cardiovascular disease prevalence 1

Clinical Presentation

• Symptoms may include dizziness, light-headedness, fatigue, weakness, and visual and hearing disturbances 1
• Pain in the neck and shoulder region (coat hanger pain), low back pain, or precordial pain may occur, particularly in autonomic failure 1
• Symptoms typically develop upon standing, are relieved by sitting or lying, and may be worse in the morning, with heat exposure, after meals, or with exertion 1
• Classic OH may be symptomatic or asymptomatic - symptoms depend more on the absolute BP level than the magnitude of the fall 1
• Symptom occurrence likely depends on cerebral autoregulation capacity 1

Pathophysiology

• Results from impaired increase in total peripheral resistance and heart rate in autonomic failure, leading to blood pooling in lower extremities 1
• Alternatively, severe volume depletion can cause the same hemodynamic pattern 1
• The prevalence in community settings is approximately 20% in older adults and 5% in middle-aged adults 2
• Associated with up to a 50% increase in relative risk of all-cause mortality 2

Differentiation from Other Forms of Orthostatic Hypotension

Initial OH

• Characterized by BP decrease >40 mmHg systolic and/or >20 mmHg diastolic within 15 seconds of standing 1
• BP spontaneously and rapidly returns to normal, with symptoms lasting <40 seconds 1
• More common in young, asthenic subjects or with alpha-blocker use 1

Delayed OH

• Occurs beyond 3 minutes of standing or head-up tilt 1
• Characterized by slow, progressive decrease in BP 1
• Absence of bradycardia helps differentiate it from reflex syncope 1
• More common in elderly persons with stiffer hearts sensitive to decreased preload 1
• May represent a mild form of classical OH, especially if associated with Parkinsonism or diabetes 1

Orthostatic VVS (Vasovagal Syncope)

• BP drop starts several minutes after standing up and accelerates until fainting occurs 1
• Low BP is short-lived compared to the sustained hypotension of classic OH 1
• Often preceded by autonomic activation (nausea, pallor, sweating) 1

Common Risk Factors and Associated Conditions

• Frailty and advanced age 1
• Medication use (vasoactive drugs, diuretics, alpha-blockers) 1
• Autonomic failure (primary or secondary to conditions like Parkinson's disease) 1
• Hypovolemia from any cause 1
• Diabetes mellitus increases prevalence across all age groups 2

Clinical Implications

• Associated with increased risk of falls 2
• Significantly increases cardiovascular risk 2
• Impaired recovery of blood pressure after initial fall represents a negative prognostic factor in the elderly 1
• Management should focus on reducing symptoms and improving quality of life while avoiding excessive supine hypertension 3

Classic OH represents a serious clinical condition that requires proper identification and management to reduce morbidity and mortality, particularly in vulnerable populations such as the elderly.