Catheter Ablation

Excerpt

Catheter ablation, particularly radiofrequency ablation has revolutionized treatment for tachyarrhythmia. It has evolved rapidly over the years and has proven to be first-line therapy for many tachycardias in most of the patients having recurrent symptoms, which limit their productivity and hinder their lifestyle. the use of catheter ablation was first introduced in the late 1960s; it was designed first for recording, where the surgical treatment of cardiac arrhythmia was the main concept. In 1967, the concept of induction of cardiac arrhythmia was first introduced through programmed electrical stimulation. in the late 1970s, Wellen was able to perform programmed electrical stimulation. and record the activation sequences from more than one recording catheter, followed by the development of both the surgical ablation and the intracardiac recordings. Previously the arrhythmia was terminated by surgical maneuvers, for example, surgical excision of the triggered arrhythmogenic focus for atrial tachycardia and cryo excision of the AV junction in case of resistant supraventricular tachycardia. The maze procedure is one of the well-known procedures, particularly during mitral valve surgery complicated with atrial fibrillation (AF), for AF termination.In 1981, the concept of the transvenous catheter was first defined when a patient that was undergoing an electrophysiological recording following defibrillation, where a high-voltage discharge was emitted when the defibrillator electrode hit the catheter electrode at His. This energy caused damage to underlying tissue.. Direct current cardioversion was first used in atrial fibrillation ablation. The direct current was delivered to the distal electrode and a surface electrode; this led to uncontrollable tissue damage. In the 1990s, radiofrequency ablation replaced the direct current. RF energy is an alternating current generated with a frequency of 350 kHz to 700 kHz (usually 500 kHz on commercially available RF generators) delivered in a continuous, unmodulated sinusoidal manner to create thermal injury. The current is delivered in a unipolar fashion from the tip of the catheter electrode to a large surface (100 cm2 to 250 cm2). A patch is placed against the skin where the electric energy is delivered and converted to thermal injury when it passes through the tissue (resistive heating). Large patches are placed on the patient's back as a ground to avoid skin burns. The tissue in direct contact with the catheter is damaged by resistive heating while deeper and surrounding tissues are heated and damaged by conductive heating. Acute lesions show inflammation and hemorrhage around a central area of coagulative necrosis. Areas with inflammation at the border of central necrosis explain the recurrence of arrhythmias later, as the area may contain viable arrhythmogenic tissue that is acutely non-conductive at the time of ablation but can conduct later after the healing process takes place. .

Current ablation equipment allows temperature monitoring and temperature control, which is a valuable tool during radiofrequency ablation procedures as it provides important information regarding the adequacy of tissue heating, minimizes the development of coagulum and lesion size. Newer technical modifications, including a larger distal electrode and saline cooling, have helped to minimize impedance rise and allow the creation of larger and deeper lesions..In this review article, we will discuss the role of catheter ablation in the management of cardiac arrhythmias, summarize the technical aspects of the procedures, highlight the indications for ablation and discuss complications associated with catheter ablation.