Mechanically induced complete atrioventricular block during retrograde catheter ablation of a left-sided incessant tachycardia.

Concern for potentially lethal complications related to transseptal catheterisation, such as perforation of the aorta, has made this approach less attractive over the last decades. Nevertheless, this method is now increasingly being used for ablation of left-sided arrhythmias. We report a transient complication of a retrograde procedure in a patient with a left-sided 'Coumel-type' incessant tachycardia. We had to proceed to transseptal catheterisation, as the complication recurred during the second attempt even when using a less rigid transaortic radiofrequency catheter. The transseptal approach using a less stiff cryoenergy catheter was performed without complications.