| Abstract: | The effects of right atrial (RA) and coronary sinus (CS) stimulation have been studied in 13 patients with circus movement tachycardia (CMT). Tachycardia entrainment has occurred in all patients during RA pacing and in 11/13 during CS pacing, for a pacing rate 10 to 31 beats faster than the tachycardia rate. During RA pacing, short episodes of right atrial ventricular dissociation (6/13 patients) occurred but not during CS pacing. This can be explained by the anatomical proximity of the CS to the AV node (AVN) or by postulating two separate lateral inputs in the upper part of the AVN. Tachycardia entrainment is a criteria in favor of a reentry mechanism. It delineates a ranges of frequency between tachycardia rate and the slowest possible atrial stimulation rate capable of tachycardia termination which may be benefit for patients with drug resistant CMT, for whom antitachycardia pacemaker is envisaged. |
