We believe that the pattern of blood pressure response to tilt during the time preceding the development of the vasovagal reaction may provide adjunctive diagnostic information. A group of 101 consecutive patients affected by syncope of uncertain origin underwent passive tilt testing for 45 min at 60 degrees followed, if negative, by oral (sublingual) trinitroglycerin (TNG) 0.4 microg with continuation of the test for 20 min. Three main patterns were observed: the classic (vasovagal) syncope pattern was observed in 36 patients who, during the preparatory phase, had a rapid and full compensatory reflex adaptation to upright position, resulting in stabilization of their blood pressure values until abrupt onset of the vasovagal reaction; the dysautonomic (vasovagal) syncope pattern was observed in 47 patients in whom steady-state adaptation to upright position was not possible. There was thus a progressive fall in their blood pressure until the occurrence of a typical vasovagal reaction; the orthostatic intolerance pattern was observed in 18 patients in whom there was a progressive fall in blood pressure, similar to that of the dysautonomic group, but this was not followed by a clear vasovagal reaction. Compared with the classic, the dysautonomic patients were older, had a higher prevalence of co-morbidities, a very much shorter history of syncopal episodes, and a prevalence of mixed and vasodepressor forms of the VASIS classification. The patients with orthostatic intolerance had clinical characteristics similar to the dysautonmic group but they could not be classified according to the VASIS classification. In conclusion, in patients with syncope, a variety of abnormal responses is observed during tilt testing, suggesting that different syndromes can be diagnosed by the test. A more detailed, although still arbitrary, classification may form the basis of a number of future drug and pacemaker trials, as well as help towards a greater understanding of the different mechanisms of tilt-induced syncope.

A simple score derived from clinical history can be usefully employed for the triage and management of patients with syncope in an ED.

Head-up tilt testing potentiated by sublingual nitroglycerin (NTG), advocated by an Italian group, is a simple and safe but still not a standardized, diagnostic tool for the investigation of syncope. In fact, owing to its rapid spread, the original protocol received, often arbitrarily, many subsequent modifications. We now define the best methodology of the test on strictly evidence-based criteria as: stabilization phase of 5 min in the supine position; passive phase of 20 min at a tilt angle of 60 degrees; provocation phase of further 15 min after 400 micrograms NTG sublingual spray. Test interruption is made when the protocol is completed in the absence of symptoms, or there is occurrence of syncope, or occurrence of progressive (> 5 min) orthostatic hypotension. We intend that this protocol, named by us as 'The Italian Protocol', will be accepted as the standard methodology of the tilt test potentiated by sublingual nitrates.

The presence of suspected or certain heart disease after the initial evaluation is a strong predictor of a cardiac cause of syncope. A few historical findings are useful to predict cardiac and neurally mediated syncope in patients with and without heart disease.

No abstract