Atrial arrhythmia following a biatrial approach to mitral valve surgery.

The biatrial approach to exposing the mitral valve during surgery has the potential for improving visualization of the valve with minimal cardiac manipulation. This procedure, involving a right atriotomy and an extended transseptal incision, may isolate the sinus node from its normal blood supply and autonomic innervation. Thirty-eight consecutive patients undergoing this procedure were examined. Twenty-two of these patients (58%) were admitted in normal sinus rhythm and 15 (40%) were in atrial fibrillation (AF) or atrial flutter. Of the 22 patients admitted in normal sinus rhythm, only 3 patients remained in this rhythm at discharge. Fourteen of the 22 patients were discharged in a slow, low atrial rhythm. All of the patients admitted in AF were discharged in AF. Of the 14 patients discharged in a low atrial rhythm, the rhythm persisted in eleven patients (80%) at a mean of 6-month follow-up. The routine use of this transseptal approach to mitral valve surgery needs further assessment in light of the predictable loss of the sinus mechanism.

Mapping reentry around atriotomy scars using double potentials.

Supraventricular arrhythmias, often seen in patients after cardiac surgery, may be associated with scars produced in the atria at the time of surgery. Double potentials, found in the presence of functional or anatomical block, can define the limits and critical regions of a reentrant circuit associated with the atriotomy scars. We describe six patients with seven distinct atrial tachycardias in whom atriotomy scars were successfully mapped during intraatrial reentry utilizing the presence and interelectrogram relationship of observed double potentials. The reentrant circuit was mapped in all patients by following the relationship between double potentials along the surgical scar, assuming that they would be widely split in the middle of the scar and merge into a single continuous fractionated potential at the apex of the scar. At this site, atrial pacing was performed to entrain the tachycardia and confirm the participation of the atriotomy scar in the clinically relevant atrial tachycardia. Radiofrequency ablation was performed from the site of electrogram fusion to the nearest anatomical obstacle. Five of seven atrial tachycardias were successfully ablated utilizing this technique over a mean follow-up of 10 months. We proposed that these double potentials and their interelectrogram relationship are an effective means of mapping atriotomy scars and guiding successful radiofrequency ablation.