Can catheter ablation cure post-infarction ventricular tachycardia?

Catheters with saline-irrigated tips have retained controlled energy delivery while allowing production of larger lesions than conventional catheters. Alternatives to radiofrequency energy like laser, ultrasound and percutaneous cryotherapy are also undergoing investigation but before energy can be delivered, localization of the site critical for maintenance of the arrhythmia is required. This is difficult because the electrophysiologist is attempting to manoeuvre a 4 mm tip catheter in a large, complex three-dimensional structure guided by twodimensional fluoroscopy, in addition to having to localize the relevant portion of diseased myocardium within a large diffusely diseased ventricle. A number of technologies have been developed to facilitate this procedure. Catheter location systems associated with electroanatomical magnetic mapping (Carto) and noncontact mapping (Ensite) have improved the accuracy of catheter location and reduced the fluoroscopy time. Identification of the arrhythmia substrate has also been improved with the advent of global cardiac mapping systems. Using such technologies for catheter ablation of post-infarction ventricular tachycardia resulted in success rates of approximately 77% but with low recurrence rates of around 10%. The ability to visualize the arrhythmia action wave front in the intact human heart has also improved our understanding of the mechanisms of post-infarction ventricular tachycardia. With this improved understanding strategies for catheter ablation are changing. An example of this is the application of linear radiofrequency lesions to transect diastolic pathways or enclose ventricular tachycardia exit sites, an approach that has proved useful in patients with haemodynamically unstable ventricular tachycardia. It has also been apparent that not all diastolic pathways have an endocardial location. This has led some investigators to approach catheter ablation of post-infarction ventricular tachycardia from the epicardium although only limited data have been published.