TILT TESTING - A USEFUL SCREEN FOR RATE-DROP RESPONSE

Tilt testing is accepted as the main tool for the diagnosis of neuroca rdiogenic syncope, particularly in the ''malignant'' vasovagal form. A s a result of experience with tilt testing, the cardiovascular respons es to head-up tilting in patients with malignant vasovagal syncope (MV VS) have been defined in respect of the vasodepressor (hypotensive) an d cardioinhibitory (bradycardic) components. Pacing therapy has been o f limited value in the past, with controversy about its role, even in the cardioinhibitory form of MVVS. With the advent of more sophisticat ed algorithms for pacing (i.e., rate-drop response [RDR], Thera DR) in response to the onset of bradycardia in MVVS, however, this therapy i s being reexamined. This article examines the blood pressure and heart rate responses to head-up tilt in patients with MVVS and examines the role of this test in screening such patients for the benefits of paci ng with RDR. Careful analysis of the pattern of blood pressure and hea rt rate response during the tilt test may allow selection of those pat ients likely to respond to RDR and may provide useful information for initial programming of the algorithm.