Atrial and ventricular burst pacing from a coronary sinus catheter: relation to position of radiofrequency transmitter.

A young woman with drug-refractory recurrent supraventricular tachycardia was managed by rapid atrial stimulation using a catheter positioned in the coronary sinus. During follow-up, radiofrequency activation of the pacemaker resulted in burst ventricular and/or atrial pacing, depending on the distance of the transmitter's antenna loop from the receiver. Current output was directly related to the distance of the transmitter's antenna loop from the receiver and ranged from 20 mA at a distance of 0 cm from the receiver to 1 mA at 5 cm. If possible, coronary sinus lead placement should be avoided for radiofrequency-activated atrial burst pacing given the large current output with direct contact of the transmitter's antenna loop to the implanted receiver and the risk for ventricular stimulation. Alteration of the spatial relationship between the transmitter and receiver can be used to decrease current output and prevent ventricular pacing if atrial burst pacing from the coronary sinus is desirable.