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Intracoronary Flecainide Induces ST Alternans and Reentrant Arrhythmia on Intact Canine Heart A Role of 4-Aminopyridine-Sensitive Current

Intracoronary Flecainide Induces ST Alternans and Reentrant Arrhythmia on Intact Canine Heart A Role of 4-Aminopyridine-Sensitive Current,Hidetada Tac

Intracoronary Flecainide Induces ST Alternans and Reentrant Arrhythmia on Intact Canine Heart A Role of 4-Aminopyridine-Sensitive Current   (Citations: 11)
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Background—The electrical alternans shown on an ST segment, ST alternans, is known as one of the most important predictors of ventricular fibrillation (VF). It has also been reported that sodium channel inhibition changes action potential configuration, especially on the repolarization phase. Thus, the sodium channel blocker may produce ST alternans and trigger reentrant arrhythmia. Methods and Results—A sodium channel blocker (disopyramide, lidocaine, or flecainide) was infused selectively into the left anterior descending coronary artery in anesthetized, open-chest dogs. Sixty unipolar electrograms were simulta- neously recorded from the entire cardiac surface of the heart. The amplitude of ST alternans (ST a) was determined as the difference in the ST-segment magnitude between 2 consecutive electrograms. We accepted the greatest STa among 60 leads for evaluation. High-dose flecainide (100 mg z kg21 z min21) increased STa and evoked a spontaneous VF. The STa in high-dose flecainide loading (8.763.4 mV; mean6SEM) was significantly greater than that in disopyramide or lidocaine (0.960.4 and 0.860.2 mV, P,0.05). Treatment of 4-aminopyridine (4-AP) suppressed the increase in STa and the occurrence of VF evoked by flecainide, while E4031 or verapamil did not inhibit those. Conclusions—Flecainide caused the ST alternans that was closely correlated to the occurrence of VF. Because the ST alternans was suppressed by 4-AP treatment, a 4-AP-sensitive current such as Ito or Isus may play an important role on this phenomenon. (Circulation. 1999;99:1637-1643.)
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    • ...Among the sodium channel blockers, disopyramide and lidocaine [61] had no effect on TWA, procainamide [62] reduced TWA amplitude, and flecainide [61] tended to increase alternans...
    • ...Among the sodium channel blockers, disopyramide and lidocaine [61] had no effect on TWA, procainamide [62] reduced TWA amplitude, and flecainide [61] tended to increase alternans...
    • ...In another study, treatment with verapamil did not suppress the ST segment alternans [61]...

    Majid Haghjooet al. Microvolt T-wave alternans: A review of techniques, interpretation, ut...

    • ...The present experiments were designed to (1) determine the plasma concentrations achieved by infusing 4AP in vivo to dogs, (2) design a loading and maintenance infusion regimen of 4AP that maintains stable plasma concentrations over time, (3) determine the effects of 4AP infusion on canine atrial and...

    Carol Matthewset al. Dose-Dependence of 4Aminopyridine Plasma Concentrations and Electrophy...

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