69 research outputs found
Right Atrial-ventricular Dissociation and Entrainment while Pacing from High Right Atrium and Coronary Sinus during Circus Movement Tachycardias
Thirteen patients with circus movement tachycardias [CMT] were studied. Twelve had leftâsided, and one, rightâsided, accessory pathways. Entrainment was possible during overdrive high right atrial stimulation in 13/13 patients, and during coronary sinus pacing in 10/12 patients. The minimal pacing rates required for this to occur were 10 to 31 beats/min faster than those of the tachycardias. Short episodes of right atrialâventricular dissociation occurred while pacing from the high right atrium [6/13 patients), but not from the coronary sinus (0/13 patients). It is possible to explain this phenomenon by postulating the existence of two distinct atrioventricular (AV) nodal inputs (one for rightâsided and the other for leftâsided impulses); it could also have been an expression of the close distance existing between the AV node and the coronary sinus. Entrainment, by defining a range of paring rates followed by resumption of the tachycardia upon the cessation of stimulation, indicated that faster rates were needed for the CMT to be interrupted. However, regardless of the pacing rate and pacing site, tachycardia termination occurred when an anterograde impulse was blocked at the. AV node. The information obtained from this study suggests that some patients with drugâresistant CMT may benefit from pacing modes capable of terminating the arrhythmia âthrough entrainmentâ at the slowest atrial rate at which this is possible
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