Key result
Five antiarrhythmics suppress sinus activity and contractility, but procainamide uniquely triggers dual adrenergic responses.
Why the study?
The effects of different antiarrhythmic drugs on sinoatrial nodal pacemaker activity and contractility in isolated blood-perfused atrium preparations were not fully characterized.
Comparison
Quinidine, procainamide, lignocaine, phenytoin, and propranolol effects
Design
Preclinical experimental study with direct drug administration into sinus node artery
Authors
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May warrant high-dose caution clinically; leaves open translation of these experimental effects to practice.
Procainamide-induced positive chronotropic and inotropic effects in isolated dog atria appear to involve an adrenergic mechanism, distinguishing it from the purely negative effects of other tested antiarrhythmics.
Shigetoshi Chiba (1976) studied this question. Antiarrhythmic drugs (quinidine, procainamide, lignocaine, phenytoin, and propranolol) was evaluated on Pacemaker activity in the sinoatrial node and contractility. Five antiarrhythmic drugs induced negative chronotropic and inotropic effects and sinus arrest at high doses, while procainamide also induced positive effects likely via an adrenergic mechanism.
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