Key result
Quinidine consistently prolonged the ventricular effective refractory period by 9% to 11% (P<0.001), regardless of the basic drive train cycle length or duration.
Why the study?
Does quinidine prolong the ventricular effective refractory period independently of pacing rate in patients undergoing electropharmacological testing?
Does quinidine prolong the ventricular effective refractory period independently of pacing rate in patients undergoing electropharmacological testing?
Quinidine prolongs the ventricular effective refractory period in humans independently of the pacing rate.
Answers are grounded in this paper and cite their sources.
Quinidine effects on ventricular refractoriness may be assessed without rate correction in EP testing; extends prior observations but leaves open outcome implications.
In this study, the rate dependent effect of quinidine on the ventricular effective refractory period (VERP) was evaluated in 30 patients undergoing electropharmacological testing with quinidine. The VERPs were measured in the baseline state and after at least 2 days of treatment with 1,458-2,044 mg/day of quinidine gluconate (mean plasma quinidine concentration 2.2 +/- 0.7 mcg/mL). In 20 patients, the VERP was measured using conventional basic drive trains of 8 beats and basic drive cycle lengths of 600, 500, 400, and 350 msec. In another 10 patients, the VERP was measured after 3 minutes of continuous ventricular pacing at cycle lengths of 600 and 400 msec, and compared to the VERPs measured at the same basic drive cycle lengths using basic drive train durations of 2 and 8 beats. In the baseline state and after treatment with quinidine, the VERP shortened progressively as the basic drive train cycle length decreased and as the drive train duration increased to 3 minutes (P less than 0.001). Quinidine consistently prolonged the VERP by 9%-11% (P less than 0.001), regardless of the basic drive train cycle length. Quinidine's effect was also not affected by the basic drive train duration. In conclusion, the effect of quinidine on VERP in humans is independent of the rate of the basic drive train, both when measured using conventional 8-beat basic drive trains and when a three minute drive train duration is used in order to attain the maximum effect of the basic drive train cycle length on the VERP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Rosenheck et al. (1990) studied Patients undergoing electropharmacological testing (n=30). Quinidine gluconate vs. Baseline was evaluated on Ventricular effective refractory period (VERP) (9%-11% prolongation, p=<0.001). Quinidine consistently prolonged the ventricular effective refractory period by 9% to 11% (P<0.001), regardless of the basic drive train cycle length or duration.
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