Tilt Testing

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SAMPLE EXCERPT
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PRE-PROCEDURE
INDICATIONS
  • To establish the diagnosis of neurogenic syncope, when the diagnosis is suggested by history but otherwise unproven
    • After a single episode in a high-risk setting or occupation
    • After multiple episodes of syncope in the absence of heart disease
  • To differentiate between neurogenic syncope and orthostatic hypotension
  • To differentiate syncope with jerky movements from seizures
  • To evaluate frequent syncopal events in patients with psychiatric disease
  • Note: NOT recommended for assessment of treatment of neurogenic syncope
CONTRAINDICATIONS

Absolute Contraindications

  • Patient refusal

Relative Contraindications

  • Syncope proven to be due to another cause
  • Syncope in patients with structural heart disease or known or presumed arrhythmias who have not undergone other evaluation, possibly including electrocardiogram, echocardiogram, ambulatory rhythm monitoring, and/or electrophysiology study

Do not use isoproterenol in those with ischemic heart disease, uncontrolled hypertension, history of ventricular arrhythmias, left ventricular outflow tract obstruction, and/or significant aortic stenosis.

EQUIPMENT
  • Tilt table
  • Blood pressure cuff and continuous ECG monitoring
  • Equipment for IV catheterization, particularly if isoproterenol will be used
    • 20-gauge IV catheter
    • Local anesthesia, 3-cc syringe, and small (25- or 30-gauge) needle for subcutaneous infiltration of local anesthetic, heparin flush and “lock”
  • Optional equipment includes arterial line or beat-to-beat blood pressure monitoring system.
  • Resuscitation equipment, including oxygen source and suction, crash cart, defibrillator, and resuscitation drugs
ANATOMY

Neurally mediated hypotension or syncope represents an abnormality of blood pressure regulation characterized by the abrupt onset of hypotension and/or bradycardia. Both orthostatic stress (prolonged standing) and emotional stress can precipitate syncope. It is hypothesized that it results from a paradoxical reflex that is initiated when venous pooling reduces ventricular preload. Cardiac output and blood pressure fall, and arterial baroreceptors cause catecholamine release. The volume-depleted ventricle contracts vigorously, leading to activation of mechanoreceptors, also called C-fibers—nonmyelinated fibers found in the atria, ventricles, and pulmonary artery. The afferent C-fibers project to the dorsal vagal nucleus of the medulla, leading to a decrease in peripheral sympathetic tone and an increase in vagal tone, with resultant vasodilation and bradycardia. Because emotional trauma can also cause neurogenic syncope, it is believed that higher neural centers can also participate in the reflex.


PROCEDURE
Sample excerpt does not include step-by-step text instructions for performing this procedure
The full content of this section includes:
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  • Links to medical evidence and related procedures

POST-PROCEDURE
CARE
  • Remove blood pressure cuff, ECG patches, and defibrillator patches.
  • Remove IV catheter if one was used and apply a bandage.
COMPLICATIONS
  • Rarely, ventricular arrhythmias have been seen with isoproterenol.
  • Asystole pauses as long as 73 seconds have been reported but are exceedingly rare.
  • Headache may occur with nitroglycerin.
  • Self-limited atrial fibrillation has been described during or after a positive test response.
RESULT ANALYSIS
  • The presence of reflex hypotension and/or bradycardia with reproduction of symptoms is diagnostic of neurocardiogenic syncope. A drop in blood pressure with a minimal change in heart rate is diagnostic of vasodepressor syncope, while a drop in heart rate with no change in blood pressure is consistent with cardioinhibitory syncope. If both heart rate and blood pressure drop, this represents a mixed cause of neurocardiogenic syncope. The presence of reflex hypotension and/or bradycardia without symptoms may represent neurocardiogenic syncope, but the diagnosis is less certain.
  • Drop in blood pressure of >20 mm Hg systolic and >10 mm Hg diastolic within 3 minutes of standing is consistent with classical orthostatic hypotension. Some patients may have a decrease in blood pressure of >40 mm Hg immediately upon standing, which is consistent with initial orthostatic hypotension.
  • Autonomic failure has an initial and continuous drop in blood pressure with no change in heart rate.
  • Postural orthostatic tachycardia syndrome shows an increase in heart rate with no change in blood pressure.
  • Induction of syncope in the absence of hypotension and/or bradycardia is diagnostic of psychogenic pseudosyncope.
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