The patient must be fasting for at least 4 hrs; should stay 5 min. in supine position and then is tilted at 60 degrees for 20 min. Then, it is administered 400 micrograms of sublingual nitroglycerin for 20 min. more. The tilt table test (TTT) is considered positive if the patient presents syncope or if the systolic blood pressure is lower than 60 mmHg. The hemodynamic variables, the HR variability, and the BP are written down for those patients who have these values available.