Tilt table testing is used to evaluate syncope in
Younger, apparently healthy patients
Elderly patients when cardiac and other tests have not provided a diagnosis
Tilt table testing produces maximal venous pooling, which can trigger vasovagal (neurocardiogenic) syncope and reproduce the symptoms and signs that accompany it (nausea, light-headedness, pallor, hypotension, bradycardia).
After an overnight fast, a patient is placed on a motorized table with a foot board at one end and is held in place by straps over the body; an IV line is inserted. After the patient remains supine for 15 minutes, the table is tilted nearly upright to 60 to 80° for 45 minutes during which symptoms and vital signs are monitored.
Relative contraindications include
If vasovagal symptoms develop, vasovagal syncope is confirmed. If symptoms do not occur, a drug (eg, isoproterenol) may be given to induce them. (NOTE: Isoproterenol should not be used in patients with hypertrophic cardiomyopathy or severe coronary artery disease.) Sensitivity varies from 30 to 80% depending on the protocol used. The false-positive rate is 10 to 15%.
With vasovagal syncope, heart rate and blood pressure (BP) usually decrease. Some patients have only a decrease in heart rate (cardioinhibitory); others have only a decrease in BP (vasodepressor). Other responses that suggest alternative diagnoses include a gradual decrease in systolic and diastolic BP with little change in heart rate (dysautonomic pattern), significant increase in heart rate (> 30 beats/minute) with little change in BP (postural orthostatic tachycardia syndrome), and report of syncope with no hemodynamic changes (psychogenic syncope).