Definition of Orthostatic Hypotension
Orthostatic hypotension is defined as a reduction of systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg within 3 minutes of standing or during head-up tilt of at least 60 degrees. 1
Types of Orthostatic Hypotension
There are several distinct types of orthostatic hypotension, each with specific characteristics:
Classical OH: A sustained decrease in systolic BP ≥20 mmHg, diastolic BP ≥10 mmHg, or a sustained decrease in systolic BP to an absolute value <90 mmHg within 3 minutes of active standing or head-up tilt. In patients with supine hypertension, a systolic BP drop ≥30 mmHg should be considered. 1
Initial OH: A BP decrease on standing of >40 mmHg for systolic BP and/or >20 mmHg for diastolic BP within 15 seconds of standing. BP then spontaneously and rapidly returns to normal, with the period of hypotension and symptoms being short (<40 seconds) but potentially still causing syncope. 1
Delayed OH: Defined as OH occurring beyond 3 minutes of head-up tilt or active standing. It is characterized by a slow progressive decrease in BP. The absence of bradycardia helps differentiate delayed OH from reflex syncope. 1
Clinical Significance and Impact
Orthostatic hypotension is associated with increased mortality and cardiovascular disease prevalence. 1
The presence of orthostatic hypotension, when due to advanced cardiovascular autonomic neuropathy (CAN), is associated with an additional increase in mortality risk. 1
OH may complicate treatment of hypertension, heart failure, and coronary heart disease; cause disabling symptoms, faints, and traumatic injuries; and substantially reduce quality of life. 2
Despite being largely asymptomatic or with minimal symptoms, the presence of OH independently increases mortality and the incidence of myocardial infarction, stroke, heart failure, and atrial fibrillation. 2
Common Symptoms
Dizziness, lightheadedness, blurred vision, weakness, fatigue, nausea, palpitations, and headache 3
Less common symptoms include syncope, dyspnea, chest pain, and neck and shoulder pain (coat hanger syndrome) 3, 4
Testing and Diagnosis
For diagnosis, blood pressure should be measured after 5 minutes of lying supine, then continued after 1 or 3 minutes of standing. 1
If the patient does not tolerate standing for this period, the lowest systolic blood pressure during the upright posture should be recorded. 1
Head-up tilt-table testing can aid in confirming a diagnosis when standard orthostatic vital signs are nondiagnostic. 3
For its ease and prognostic value, orthostatic hypotension should be assessed routinely in diabetic patients even without symptoms, particularly after the age of 50. 1
Management Considerations
Treatment goals involve improving hypotension without excessive supine hypertension, relieving orthostatic symptoms, and improving standing time. 3
Treatment includes correcting reversible causes and discontinuing responsible medications when possible. 3
Nonpharmacologic treatment should be offered to all patients before considering pharmacologic options. 3, 4
For patients who do not respond adequately to nonpharmacologic treatment, medications such as midodrine may be beneficial. Midodrine forms an active metabolite that is an alpha1-agonist, producing an increase in vascular tone and elevation of blood pressure. 5, 3
Understanding the definition and proper diagnosis of orthostatic hypotension is critical for appropriate management and reducing associated morbidity and mortality risks.