Key result
Isoprenaline shortens refractory period and cuts temporal dispersion ~65% in quinidine-induced long QT.
Why the study?
The mechanisms underlying changes in ventricular refractory period and temporal dispersion in quinidine-induced long QT interval and the effects of heart rate, isoprenaline, and lignocaine were not fully understood.
Mean Difference: -29
Absolute Event Rate: 228% vs 257%
p-value: p=<0.001
In a canine model of quinidine-induced long QT, isoprenaline significantly reduced both the effective refractory period and its temporal dispersion, providing a mechanistic basis for its efficacy in suppressing polymorphous ventricular tachycardia.
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Should not change practice in long QT; hypothesis-generating and requires human validation.
Inoue et al. (1985) studied Quinidine-induced long QT interval (n=19). Isoprenaline and lignocaine vs. Baseline (quinidine alone) was evaluated on Effective refractory period (ERP) (p=<0.001). In dogs with quinidine-induced long QT, isoprenaline significantly shortened both effective refractory period (257 vs 228 ms, p<0.001) and temporal dispersion (34 vs 12 ms, p<0.01).
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