Catheter ablation of focal triggers and drivers of atrial fibrillation

A brief overview of surgery for atrial fibrillation

The Maze procedure was the first surgical technique developed to ablate, rather than isolate, atrial fibrillation and was first performed clinically in 1987. The experimental and clinical electrophysiological maps on which the Maze procedure was based demonstrated the presence of two or more large (5-6 cm diameter) macro-reentrant circuits during established atrial fibrillation (AF). Eleven years later, focal triggers were identified, primarily in and around the pulmonary veins, and were shown to be responsible for the induction of individual episodes of AF. Thus, it became clear that episodes of paroxysmal AF could be treated in most patients by isolating or ablating the region of the pulmonary veins, but that once AF became non-paroxysmal and thus dependent upon the macro-reentrant circuits for its maintenance, it would still be necessary to perform some type of additional procedure to interrupt those circuits. Approximately 100,000 patients who undergo coronary artery bypass grafting (CABG), aortic valve replacement (AVR) or mitral valve surgery in the US also have associated AF, but only 20% of them undergo a concomitant procedure to ablate the AF. However, multiple studies have demonstrated that treating the AF at the time of these other primary operations results in an improved quality of life, fewer long-term strokes and improved long-term survival while adding no risk to the overall surgical procedure. Moreover, the major cardiology and surgery societies recommend that concomitant AF surgery be performed in all cases when feasible. Patients undergoing CABG and AVR who have paroxysmal AF should undergo pulmonary vein isolation, while those with non-paroxysmal AF (persistent or long-standing persistent AF) should have a Maze procedure. Patients undergoing mitral valve surgery who have either paroxysmal AF or non-paroxysmal AF should undergo a Maze procedure.

Atrial tachycardia initiating atrial fibrillation successfully ablated in the non-coronary cusp of the aorta

A 60-year-old woman was referred for catheter ablation of atrial fibrillation (AF). Atrial flutter and atrial tachycardia (AT) also had been clinically documented. During the electrophysiological study, the clinical AT was induced by burst atrial pacing during isoproterenol infusion and exhibited negative P waves in the inferior leads, positive P waves in leads I, aVL, and aVR, and biphasic P waves in lead V1. The AT repeatedly and spontaneously accelerated to initiate AF by causing fibrillatory conduction in the atria. Successful catheter ablation of the AT was achieved in the non-coronary cusp of the aorta (NCC) where the local atrio-ventricular electrogram amplitude ratio was >1 during both the AT and sinus rhythm. The tailored approach targeting the NCC AT alone without left atrial ablation completely eliminated the AF. In catheter ablation of AF in a patient with a co-existing clinical AT, it may be recommended to examine the clinical AT first. If the clinical AT initiates the AF and local atrial activations in the His bundle region precede the P wave onset during AT, mapping in the NCC should be considered prior to left atrial catheterization.