The safety and efficacy of intravenous
quinidine gluconate, using intermittent boluses of 80 mg/cc every 5 minutes to a total dose of 800 mg, was evaluated in 61 patients referred for electrophysiologic studies (EPS). Patients were referred because of
out-of-hospital cardiac arrest (12), symptomatic
ventricular tachycardia (VT) (24), asymptomatic VT (18),
syncope of unknown origin (6), and supraventricular arrhythmias (1). Clinical
heart failure was present in 74% of patients, with a mean ejection fraction of 45 +/- 3 for all patients.
Quinidine prevented VT induction in 78% of patients at a mean dose of 9.6 mg/kg and facilitated VT induction in 7% of patients.
Quinidine failed to decrease mean arterial pressure in 14 patients, and in the remaining 47 patients arterial pressure decreased by 16%. Six patients had hemodynamically significant
hypotension. Two patients had
hypotension severe enough to require saline administration, while four had
hypotension not needing fluid replacement. Sixteen percent of patients experienced other side effects.
Quinidine can be administered safely by intermittent infusion and is effective in preventing programmed stimulation induction of VT. Carefully monitored, intravenous intermittent bolus administration of
quinidine should be utilized more frequently in EPS, since significant adverse side effects are infrequent.