Twenty patients with recurrent sustained ventricular tachycardia (VT) underwent serial electrophysiological studies (EPS) 1) to determine the predictive value of the EPS in the selection of antiarrhythmic therapy, and 2) to establish the therapeutic efficacy of available antiarrhythmic agents. In each patient VT could be reproducibly initiated by programmed stimulation. After control EPS, the e...

PURPOSE The purpose of this study is to evaluate the demethylating and tumor suppressor-reactivating activity of hydralazine and procainamide. EXPERIMENTAL DESIGN MDA-231, MCF-7, and T24 cell lines were treated for 5 days with 10 micro M hydralazine or 10 micro M procainamide. 5-aza-deoxycytidine at 0.75 micro M was used as positive control. BALB/c nu/nu mice xenografted with MDA-231 cells we...

BACKGROUND Use-dependent effects of antiarrhythmic drugs on phase 0 sodium current result in rate-dependent conduction slowing with important potential clinical consequences. The purpose of the present study was to determine whether state-dependent interactions of procainamide with sodium channels can be analyzed based on conduction changes in vivo. METHODS AND RESULTS Procainamide infusions ...

To evaluate the mechanisms of action of procainamide on the components of the reentrant pathway, drug-induced changes in activation patterns, effective refractory periods (ERPs), and stimulation thresholds were analyzed in nine dogs with sterile pericarditis and sustained atrial flutter. Activation maps were based on 127 close bipolar recordings from a special "jacket" electrode. From the contr...

Serial electrophysiologic testing of multiple drugs was performed in 21 patients with recurrent atrioventricular (AV) nodal reentrant paroxysmal supraventricular tachycardia (PSVT). All patients had reproducible sustained PSVT induced before drug administration. Serial daily PSVT induction was attempted after administration of i.v. ouabain (0.01 mg/kg) (16 patients), i.v. propranolol (0.1 mg/kg...

Purpose: The purpose of this study is to evaluate the demethylating and tumor suppressor-reactivating activity of hydralazine and procainamide. Experimental Design: MDA-231, MCF-7, and T24 cell lines were treated for 5 days with 10 M hydralazine or 10 M procainamide. 5-aza-deoxycytidine at 0.75 M was used as positive control. BALB/c nu/nu mice xenografted with MDA-231 cells were treated with th...

JN, Lau SH: Time dependent changes in the functional properties of the atrioventricular conduction system in man. Circulation 52: 1012, 1975 10. Dhingra RC, Denes P, Wu D, Chuquimia R, Rosen KM: The significance of second degree atrioventricular block and bundle branch block. Observations regarding site and type of block. Circulation 49: 638, 1974 11. Dhingra RC, Denes P, Wu D, Chuquimia R, Ama...

BACKGROUND Type I antiarrhythmic drugs block the cardiac sodium channel in a use-dependent fashion. This use-dependent behavior causes increased drug binding and consequently increased sodium channel blockade at faster stimulation rates. Importantly, the kinetics of drug association and dissociation from the sodium channel differ for each type I antiarrhythmic drug. METHODS AND RESULTS Thirty...

The cycle length dependence of the action potential duration and the effective refractory period of the right ventricular endocardium were investigated in 24 patients undergoing electrophysiologic studies for suspected ventricular tachycardia. The action potential duration at 90% repolarization and the effective refractory period at twice diastolic threshold strength were measured at the same c...

1-Aminobenzotriazole (ABT) has been used widely as a nonselective in vitro and in vivo inhibitor of cytochrome P450 enzymes. To date, however, it has not been evaluated as an inhibitor of UDP-glucuronosyltransferase (UGT), sulfotransferase (SULT), and N-acetyltransferase (NAT). In the present study, ABT was shown not to inhibit UGT and SULT activity (acetaminophen and 7-hydroxycoumarin as subst...