From the Guidelines
Persistent orthostatic hypotension is primarily caused by autonomic nervous system dysfunction, volume depletion, and medication side effects, as well as other factors such as neurodegenerative disorders, endocrine disorders, and age-related changes. The causes of persistent orthostatic hypotension can be multifactorial, including neurogenic causes like neurodegenerative disorders (e.g., Parkinson's disease, multiple system atrophy, and diabetic neuropathy) which impair the body's ability to constrict blood vessels when standing 1. Volume depletion from dehydration, blood loss, or excessive diuresis can also reduce circulating blood volume, contributing to orthostatic hypotension. Medications commonly implicated include antihypertensives, diuretics, vasodilators, antidepressants, and Parkinson's medications, which can exacerbate orthostatic intolerance 1.
Key Factors Contributing to Orthostatic Hypotension
- Autonomic nervous system dysfunction
- Volume depletion
- Medication side effects
- Neurodegenerative disorders
- Endocrine disorders (e.g., adrenal insufficiency, hypothyroidism)
- Age-related changes in baroreceptor sensitivity and vascular stiffness
Management Strategies
- Addressing underlying causes
- Medication adjustments
- Increasing fluid and salt intake
- Compression stockings
- Sometimes medications like midodrine or fludrocortisone to increase blood pressure, as noted in recent guidelines 1. The therapeutic goal is to minimize postural symptoms rather than to restore normotension, and management typically involves a combination of nonpharmacologic and pharmacologic measures. Physical activity and exercise should be encouraged to avoid deconditioning, which is known to exacerbate orthostatic intolerance, and volume repletion with fluids and salt is critical 1.
From the Research
Causes of Persistent Orthostatic Hypotension
The causes of persistent orthostatic hypotension are varied and can be attributed to several factors, including:
- Aging, which can lead to a decline in baroreflex function and an increase in venous pooling 2
- Diseases such as diabetes and Parkinson's disease, which can cause baroreflex failure and result in a combination of orthostatic hypotension, supine hypertension, and loss of diurnal variation of blood pressure 2
- Autonomic nervous system dysfunction, which can be caused by neurological or non-neurological diseases and conditions 3
- Non-neurogenic disorders, such as dehydration, anemia, and certain medications 4
- Structural factors, such as varicose veins, and infravascular volume 4
Mechanisms and Influencing Factors
The mechanisms and influencing factors that contribute to orthostatic hypotension include:
- Baroreflex failure, which can result in an inability to regulate blood pressure in response to changes in posture 2
- Venous pooling, which can lead to a decrease in blood volume and a subsequent decrease in blood pressure 2
- Hormonal changes, such as a decrease in circulating and local hormones, which can influence blood pressure regulation 4
- Daily life factors, such as dehydration, physical inactivity, and certain medications, which can exacerbate orthostatic hypotension 4, 5
Prevalence and Prognosis
Orthostatic hypotension is a common cardiovascular disorder, with a prevalence that increases with age, ranging from 5% in patients under 50 years of age to 30% in those over 70 years of age 6. The presence of orthostatic hypotension has been shown to independently increase mortality and the incidence of myocardial infarction, stroke, heart failure, and atrial fibrillation 6.