Protocols for tilt testing

Acceptable tilt test protocols⁶

Tilt test protocols vary, but a generally acceptable protocol (for evaluating adult patients) involves an initial drug-free tilt at 60-80°, lasting 30-45 minutes. If this is non-diagnostic, then pharmacological provocation is used.⁶

Laboratory and environment⁶

Dim lighting, comfortable temperature, quiet environment.
Tilt table capable of angles of 60-80°.
Minimum of three lead electrocardiographic recording.
Continuous beat to beat blood pressure recording.
Emergency resuscitation equipment on standby.

Patient⁶

Fasting after midnight or at least several hours before tilt test.
Intravenous access for fluid replacement.
Supine period of 20-45 minutes to allow equilibration.
Initial drug-free tilt for 30-45 minutes at 60-80°.

Pharmacological agents

Drug-free tilt: low sensitivity in elderly patients (>60 years of age).^w2
Isoproterenol infusion or sublingual nitroglycerin most commonly used.
Isoproterenol—Exogenous catecholamine used to help identify patients susceptible to neurocardiogenic syncope. Plasma concentrations of adrenaline (epinephrine) and noradrenaline (norepinephrine) increase significantly when patients are gradually tilted.⁶ Low dose isoproterenol (1-2 ľg/min) is well tolerated in elderly patients but has low sensitivity^w2; high dose (5ľg/min) has high sensitivity but has more adverse side effects such as warmth, diaphoresis, palpitations, nausea, palpitations, and chest discomfort, and is thus poorly tolerated.^w2
Nitroglycerin (400 g sublingual)—Nitrate used to help increase sensitivity of tilt testing in elderly patients, by elimination of the diminished blood pooling and baroreceptor activation associated with postural changes^w2; generally well tolerated; main side effect is headache. Compared with isoproterenol, nitroglycerin increases sensitivity of tilt testing in elderly patients.^w2

Endpoints⁶

Positive—If syncopal symptoms with hypotension, bradycardia, or both occur as a consequence of the procedure; if syncope occurs as a result of hypotension, bradycardia, or both.⁶
Negative—No response; or bradycardia or hypotension, without presyncopal or syncopal symptoms.⁶

Diagnostic capability and reproducibility⁶

85% diagnostic specificity³ (90%, with pharmacological provocation^2,6).
Sensitivity ranges from 32% to 85%,⁶ with 87% sensitivity when pooled data are used.³
Reproducibility ranges from 65% to 85%.⁶

** For more extensive reading, refer to ESC and ACC guidelines.**

Additional references

w1 Ventura R, Maas R, Zeidler D, Schoder V, Nienaber CA, Schuchert A, et al. A randomized and controlled pilot trial of beta-blocker for the treatment of recurrent syncope in patients with a positive or negative response to head-up tilt test. Pacing Clin Electrophysiol 2002;25:816-21.

w2 Mahanonda N, Bhuripanyo K, Kangkagate C, Wansanit K, Kulchot B, Nademanee K, et al. Randomized double-blind, placebo-controlled trial of oral atenolol in patients with unexplained syncope and positive upright tilt table test results. Am Heart J 1995;130:1250-3.

w3 Takata TS, Wasmund SL, Smith ML, Li JM, Joglar JA, Banks K, et al. Serotonin reuptake inhibitor (paxil) does not prevent the vasovagal reaction associated with carotid sinus massage and/or lower body negative pressure in healthy volunteers. Circulation 2002;106:1500-4.

w4 Mitro P, Trejbal D, Rybar AR. Midodrine hydrochloride in the treatment of vasovagal syncope. Pacing Clin Electrophysiol 1999;22:1620-4.

w5 Yu JC, Sung RJ. Clinical efficacy of propantheline bromide in neurocardiogenic syncope: pharmacodynamic implications. Cardiovasc Drugs Ther 1997;10:687-92.

w6 Natale A, Sra J, Akhtar M, Kusmirek L, Tomassoni G, Leonelli F, et al. Use of sublingual nitroglycerin during head-up tilt-table testing in patients >60 years of age. Am J Cardiol 1998;82:1210-3.