From the Guidelines
The workup for syncope secondary to hypotension should begin with a thorough history and physical examination, focusing on potential causes of decreased blood pressure, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Initial Evaluation
The initial evaluation should include:
- Initial vital signs, including orthostatic measurements (blood pressure and heart rate while lying, sitting, and standing)
- Laboratory tests, such as complete blood count, basic metabolic panel, and cardiac biomarkers like troponin
- An electrocardiogram (ECG) to identify arrhythmias or conduction abnormalities
Additional Testing
Additional testing may include:
- Echocardiography to assess cardiac function and structure, particularly if cardiac causes are suspected
- Ambulatory cardiac monitoring (Holter or event monitor) for 24-48 hours or longer for recurrent unexplained episodes
- Tilt-table testing in cases where vasovagal syncope is suspected
Management
Management of syncope secondary to hypotension may involve:
- Acute water ingestion, which can temporarily restore orthostatic tolerance in patients with neurogenic orthostatic hypotension (OH) 1
- Physical counter-pressure maneuvers, such as leg crossing or squatting, which can increase blood pressure
- Compression garments, which can improve orthostatic symptoms and blunt associated decreases in blood pressure
- Medications, such as midodrine, droxidopa, or fludrocortisone, which can be beneficial in patients with syncope due to neurogenic OH 1
Considerations
The workup and management should be tailored to the patient's age, comorbidities, and clinical presentation, with the goal of identifying reversible causes and preventing recurrence. Volume status assessment is crucial, especially in patients taking diuretics or those with potential volume depletion. Medication review is also important, as many drugs can cause or exacerbate hypotension.
From the FDA Drug Label
Midodrine hydrochloride tablets are indicated for the treatment of symptomatic orthostatic hypotension (OH) The FDA drug label does not answer the question.
From the Research
Workup for Syncope Secondary to Hypotension
The workup for syncope secondary to hypotension involves a thorough evaluation to determine the underlying cause of the hypotension. The following steps are recommended:
- Take a detailed history to identify potential causes of hypotension, such as dehydration, bleeding, or medication side effects 2, 3
- Perform a physical examination, including orthostatic assessment, to evaluate for signs of hypotension and potential underlying causes 2, 3
- Obtain an electrocardiogram (ECG) to evaluate for cardiac causes of syncope, such as arrhythmias or cardiac conduction abnormalities 2, 3
- Consider laboratory testing, such as complete blood count, electrolyte panel, and renal function tests, to evaluate for potential underlying causes of hypotension 2, 3
- Use clinical decision rules, such as the San Francisco Syncope Rule, to assess the short-term risk of death and the need for hospital admission 2, 3
Treatment of Syncope Secondary to Hypotension
The treatment of syncope secondary to hypotension depends on the underlying cause. The following treatments may be considered:
- Fluid replacement and salt supplementation to increase blood volume and blood pressure 4, 5
- Medications, such as midodrine or fludrocortisone, to increase blood pressure and prevent syncope 4, 5, 6
- Lifestyle modifications, such as increasing fluid and salt intake, and practicing counter-pressure maneuvers, to prevent syncope 6
- Cardiac device placement or ablation may be considered for cardiac causes of syncope 2
Pharmacological Treatment
Pharmacological treatment for syncope secondary to hypotension may include: