Radiofrequency Ablation - Use in Cardiology

Use in Cardiology

Radiofrequency energy is used in heart tissue or normal parts to destroy abnormal electrical pathways that are contributing to a cardiac arrhythmia. It is used in recurrent atrial flutter, atrial fibrillation (AF), supraventricular tachycardia (SVT), atrial tachycardia and some types of ventricular arrhythmia. The energy-emitting probe (electrode) is at the tip of a catheter which is placed into the heart, usually through a vein. This catheter is called the ablator. The practitioner first "maps" an area of the heart to locate the abnormal electrical activity (electrophysiology study) before the responsible tissue is eliminated. Ablation is now the standard treatment for SVT and typical atrial flutter and the technique can also be used in AF, either to block the atrioventricular node after implantation of a pacemaker or to block conduction within the left atrium, especially around the pulmonary veins. In some conditions, especially forms of intra-nodal re-entry (the most common type of SVT), also called atrioventricular nodal reentrant tachycardia or AVNRT, ablation can also be accomplished by cryoablation (tissue freezing using a coolant which flows through the catheter) which avoids the risk of complete heart block - a potential complication of RF ablation in this condition. Recurrence rates with cryoablation are higher, though. Microwave ablation, where tissue is ablated by the microwave energy "cooking" the adjacent tissue, and ultrasonic ablation, creating a heating effect by mechanical vibration, or laser ablation have also been developed but are not in widespread use.

In 2004, former British prime minister Tony Blair underwent RF catheter ablation for recurrent atrial flutter.

In AF, the abnormal electrophysiology can also be corrected surgically. This procedure, referred to as the "Cox maze procedure", is mostly performed concomitantly with cardiac surgery.

A new and promising indication for the use of RF technology has made news in the last few years. Hypertension (high blood pressure) is a very common condition, with about 1 billion people over the world, nearly 75 million in the US alone. Complications of inadequately controlled hypertension are many and have both individual and global impact. Treatment options include medications, diet, exercise, weight reduction and meditation. Inhibition of the neural impulses that are believed to cause or worsen hypertension has been tried for a few decades. Surgical sympathectomy has helped but not without significant side effects. Using RF-generated heat to ablate nerve endings in the renal arteries was found to help in cases of 'resistant hypertension' (defined as blood pressure readings over 150/90 despite three antihypertensive medications). The procedure is non-surgical and comparatively simpler to perform. The initial experience has been very encouraging. More clarification (in terms of long term success, side effects and complications) is needed. If the initial positive experience holds up, the procedure may have far reaching benefits in a few other conditions as well.