[Electrophysiologic effect of a new Ca(2+)-antagonist, TA-3090 on supraventricular tachycardia and conduction system]

We investigated the effect of a new Ca-antagonist, TA-3090 on supraventricular tachycardia (SVT) and conduction system, comparing it with the effect of Diltiazem Hydrochloride, in 11 patients who had paroxysmal SVT attacks. Seven of the 11 patients presented atrioventricular reentrant tachycardia (AVRT) via retrograde concealed conduction through an accessory pathway, and the others presented AV nodal reentrant tachycardia (AVNRT). After SVT was induced by means of programmed electrical stimulation at high right atrium, TA-3090 (0.1 mg/kg body weight) or Diltiazem (0.2 mg/kg) was administered intravenously for 3 minutes. TA-3090 terminated nine of 11 SVTs, while Diltiazem terminated four of 4 SVTs. On termination of SVT, both drugs interrupted A-H conduction during AVRT and the slow pathway during AVNRT. After TA injection, five of 11 SVTs could not be induced by programmed electrical stimulation, while two of 4 SVTs could not be induced after Diltiazem. In AVRT, three patients in which TA-3090 prevented SVT induction had a longer AV node effective refractory period than that of the others in which TA-3090 could not prevent SVT (330 +/- 46 vs 210 +/- 24 msec, p less than 0.01). However, SVT was induced more easily than before in three of the 11 patients treated with TA-3090 administration, and in one of the 4 patients treated with Diltiazem administration.(ABSTRACT TRUNCATED AT 250 WORDS)