procainamide and amiodarone similarly increased the vt cycle length ( +68 vs. +61 msec ) , the corrected qt interval ( +63 vs. +49 msec ) , and the ventricular effective refractory period measured at paced cycle lengths of 600-550 msec ( +23 vs. +21 msec ) and 400 msec ( +25 vs. +23 msec ) .
C0033216
procainamide
C0042514
vt