in the second patient in whom preexcitation disappeared after intravenous injection of ajmaline or procainamide as well as during exercise testing , atrial pacing showed 1:1 conduction over the accessory pathway at a cycle length of 220 msec and the shortest r-r interval during induced atrial fibrillation was 190 msec .
C0033216
procainamide
C0004238
atrial fibrillation