to determine if paced cycle length-dependent changes in the qrs duration correlate with the change in ventricular tachycardia ( vt ) cycle length after procainamide , we measured the qrs duration during sinus rhythm and during right ventricular pacing before and after procainamide ( mean concentration , 9.9 micrograms/ml ) in 18 patients with morphologically identical vt induced at both study periods .
C0033216
procainamide
C0042514
vt