Minimal Access Atrial Fibrillation Surgery

Abstract

Atrial fibrillation (AF) is a common supraventricular arrhythmia associated with symptoms of varying severity. AF is the most common sustained arrhythmia in the United States. Paroxysmal AF is defined as recurrent AF (∙2 episodes) that terminates spontaneously within 7 days. Persistent AF is defined as AF which is sustained beyond 7 days or lasting less than 7 days but necessitating pharmacologic or electrical cardioversion. Long-standing persistent AF is defined as continuous AF of greater than 1 year duration. Permanent AF refers to long-standing AF and where the decision was made not to restaure in sinus rhythm by any means. Mechanisms of AF are incompletely understood; however two major mechanisms predominate which are multiple random propagating wavelets and focal triggers. Paroxysmal AF represents 12% of the patients with AF and can be due to either focal AF or wavelet AF, while patients with persistent or permanent AF represent 88% and have multiple wavelets AF. This has important therapeutic implications since focal AF is often triggered by a focal source originating usually around the pulmonary veins, and the ablation of that focal trigger can eliminate AF. In the multiple wavelet hypotheses, AF results from the presence of multiple reentrant wavelets occurring simultaneously in the left and right atria, and treatment will require more ablation than the pulmonary veins which include the creation of an anatomical pattern of myocardial scar. The corridor procedure, the radial maze procedure, and the Cox maze I-III surgically create anatomical patterns designed to disrupt the reentry circuits of AF by dividing the atria into nonconductive segments. Despite its proven efficacy, the Cox maze procedure did not gain widespread application due to its complexity and technical difficulty. Therefore many groups worldwide replaced the “cut and saw technique,” with linear lines of ablation. These ablations lines are created using a variety of energy sources including radiofrequency energy, microwave, cryoablation, laser, and high-intensity focused ultrasound (HIFU). Surgical ablation is based on the principle that the predominant mechanism of development and persistent AF is reentry stimulated by ectopic triggers. Thus the techniques consist of creating an intricate pattern of lesions inducing scarring in predefined areas in the atrial wall which effectively blocks the propagation of reentrant circuits while preserving normal conduction from the sinus to the AV node.