Multiple protocols have been developed varying the angle tilt, its duration, and the concomitant use of pharmacologic agents. The patient is placed supine and vital signs are closely monitored to obtain a personal baseline. It is recommended that if venous cannulation had been performed prior to the test, the monitoring period should be longer. Another important consideration is to avoid invasive intra-arterial blood pressure monitoring during TTT because catheterization may induce in some individuals a vasovagal reaction. The patient is positioned in a head-up position. The recommendation is that the tilt angle be between 60° and 70°; however, steeper angles have been described. Heart rate and blood pressures are recorded every 3–5 min and a symptom diary is maintained. Pharmacologic agents can induce symptoms in patients that have remained asymptomatic. Isoproterenol, a non-specific beta agonist, used as an infusion is commonly employed. The infusion is titrated from 1–3 mcg/min to increase the heart rate up to 25 % above the recorded baseline, and then the head-up tilt phase of the study begins. Another important consideration is that isoproterenol is contraindicated in patients with ischemic heart disease. Nitrates have also been showed to have some use in tilt table testing, intravenous infusion or sublingual nitrates. Nitrates work by inducing venodilation, and, thus, reducing cardiac preload, stroke volume, and output. Yet, it does not hamper increases in heart rate or arterial constriction. Like isoproterenol, nitrates decrease the exam duration but are better-tolerated and easier to use [2].

Test interpretation depends on the clinical setting for indication in the first place. In patients without structural heart disease, TTT is determined to be diagnostic for different outcomes. First, for the evaluation of reflex hypotension or bradycardia that may, or not, be accompanied of spontaneous syncope. Secondly, when the patient develops progressive orthostatic hypotension even if there are no associated symptoms. In selected patients being assessed for POTS, TTT may play a diagnostic role, but it is still discretionary to the ordering physician. In patients with structural heart disease, arrhythmias should be excluded before considering a test to be diagnostic. Reproduction of a syncopal event even in the absence of hypotension or bradycardia is in turn suggestive of psychogenic pseudosyncope. The rate of false positives and negatives depends on the patient population; however, these are difficult to estimate given that there is no gold standard testing for comparison.

If the patient has remained asymptomatic during TTT, and there is suspicion for false negative results, it is recommended that the test be repeated using isoproterenol. Though relatively safe for most patients, isoproterenol should be avoided in patients with angina and history of arrhythmia. While most make no discriminations regarding test results when isoproterenol is used, some cardiologists make the distinction that a test is positive only if there is loss of consciousness or postural tone. Nonetheless, the most current guidelines do not include separate diagnostic criteria for TTT with concomitant isoproterenol [2]. Nitrates, like isoproterenol, may increase the rate of false positives. Trials comparing nitroglycerin to isoproterenol have been conducted, thus, showing similar results; however, sublingual nitroglyerine was simpler to administer, much better tolerated, and safer than low-dose isoproterenol [3, 4].