Efficacy of disopyramide on vasovagal syncope induced by head-up tilt test.

Long-Term Effects of Pharmacological Therapy for Vasovagal Syncope on the Basis of Reproducibility During Head-Up Tilt Testing

“…15,[21][22][23][24] The reported acute efficacy of disopyramide ranges from 20 to 90% with a mean of 87%. 17,[25][26][27][28][29]30 In the present study, 55% of the patients responded effectively to acute administration of intravenous disopyramide. Overall, the -adrenergic blocker therapy was more effective than that with disopyramide.…”

“…Concerning this, we have reported that the optimal dose of isoproterenol is 0.02 or 0.03 g/kg per min. 25 The present study used these doses.…”

“…14 In fact, most patients show a marked increase in heart rate and a low frequency/high frequency ratio that reflects sympathetic activity in heart rate variability immediately before vasovagal syncope during HUT testing. [14][15][16][17][18][19]25 Consequently, if a positive response is not observed with a HUT alone, the addition of isoproterenol infusion further increases the heart rate and inotropism, mimicking the increased catecholamine discharge provoked by stressful stimulation that occurs in vasovagal syncope. Thus, isoproterenol provocation as part of a HUT has recently proved to be of great help in inducing vasovagal syncope.…”

“…17,25,[28][29][30] Beta-adrenergic blockers are speculated to exert their effect via negative inotrophic actions, which are thought to diminish the degree of cardiac mechanoreceptor activation, or by acting elsewhere to oppose the high level of catecholamine. In the present study, 80% of the patients had an apparently beneficial response to the acute administration of intravenous propranolol.…”