Medication Summary
The goals of pharmacotherapy are to reduce morbidity and prevent complications.
Vasodilators
Class Summary
Vasodilators decrease preload and/or afterload.
Nitroglycerin sublingual (Nitrostat)
This agent causes relaxation of vascular smooth muscle by stimulating intracellular cyclic GMP; the result is a decrease in blood pressure. Dosage forms include SL, TD, and IV preparations. The distinction between short-acting preparations for treatment of acute attacks and long-acting preparations for prevention of recurrent episodes is important.
Administration of 300-400 µg of sublingual nitroglycerine) in order to increase average heart rate by approximately 20-25% over baseline to trigger abnormal responses in susceptible patients after a tilt stabilization phase of 5 minutes. [4]
Beta1/Beta2 Adrenergic Agonists
Class Summary
When given systemically, isoproterenol stimulates beta receptors in the heart, which produces positive inotropic and chronotropic effects. This results in increased cardiac output.
Isoproterenol (Isuprel)
Isoproterenol has sympathomimetic effects; specifically, beta1- and beta2-adrenergic receptor agonist activity.
Intravenous medication used in incremental doses (usually 3 µg/min) in order to increase average heart rate by approximately 20-25% over baseline to trigger abnormal responses in susceptible patients after a tilt stabilization phase of 20 minutes. [4]
Isotonic Crystalloids
Class Summary
Isotonic sodium chloride (normal saline [NS]) is a standard crystalloid intravenous (IV) fluid used for initial volume resuscitation. It expands the intravascular and interstitial fluid spaces. Typically, about 30% of administered isotonic fluid stays intravascular; therefore, large quantities may be required to maintain adequate circulating volume.
Normal saline (NS, 0.9% NaCl)
NS restores interstitial and intravascular volume. Administer a 250-mL bolus of 0.9% NaCl for hypotension.
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Patient undergoing upright tilt-table testing.
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Tilt-table test.
Tables
Recommendations |
Class |
level |
Tilt table is indicated in the case of an unexplained single syncopal episode in high-risk settings (eg, occurrence of, or potential risk of physical injury or with occupational implications)or recurrent episodes in the absence of organic heart disease, after cardiac causes of syncope have been excluded |
I |
B |
Tilt testing is indicated when it is of clinical value to demonstrate susceptibility to reflex syncope to the patient |
I |
C |
Tilt testing should be considered to discriminate between reflex and orthostatic hypotensive syncope |
IIa |
C |
Tilt testing may be considered for differentiating syncope with jerking movement from epilepsy |
IIb |
C |
Tilt testing may be indicated for evaluating patients with recurrent unexplained falls |
IIb |
C |
Tilt testing may be indicated for evaluating patients with frequent syncope and psychiatric disease |
IIb |
C |
Tilt testing is not recommended for assessment of treatment |
III |
B |
Isoproterenol tilt testing is contraindicated in patients with ischemic heart disease |
III |
C |
Type 1 - Mixed |
Heart rate falls at the time of syncope, but the ventricular rate does not fall to less than 40 beats/min-1 or falls to less 40 beats/min-1 for less than 10 s with or without asystole of less than 3 s. Blood pressure falls before the heart rate falls. |
Type 2 - Cardioinhibitory |
A) Cardioinhibition without asystole: heart rate falls to a ventricular rate less than 40 beats/min-1 for more than 10 s, but asystole of more than 3 s does not occur before the heart rate falls. B) Cardioinhibition with asystole: Asystole occurs for more than 3 s. Blood pressure falls with or occur before the heart rate fall. |
Type 3 - Vasodepressor |
Heart rate does not fall more than 10% from its peak at the time of syncope. |
|
Exception 1. Chronotropic incompetence: No heart rate rise during the tilt testing (ie, less than 10% from the pre-tilt rate). |
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Exception 2. Excessive heart rate rise: An excessive heart rate both at the onset of the position and throughout its duration before syncope (ie, greater than 130 beats/min-1). |
