**4.16. Catheter ablation for paroxysmal atrial fibrillation**

162 Hyperthermia

and ligation as the technique for elimination of saphenous vein reflux. One of the endovenous techniques is a radiofrequency-based procedure. Newer methods of delivery of radiofrequency were introduced in 2007. Endovenous procedures are far less invasive than surgery and have lower complication rates. The procedure is well tolerated by patients, and it produces good cosmetic results. Excellent clinical results are seen at 4-5 years, and the long-term efficacy of the

The US Food and Drug Administration (FDA) cleared the original radiofrequency endovenous procedure in March 1999. Endovenous techniques (endovenous laser therapy, radiofrequency ablation, and endovenous foam sclerotherapy) clearly are less invasive and are associated with fewer complications compared with more invasive surgical procedures, with comparable or greater efficacy. The original radiofrequency endovenous ablation system worked by thermal destruction of venous tissues using electrical energy passing through tissue in the form of high-frequency alternating current. This current was converted into heat, which causes irreversible localized tissue damage. Radiofrequency energy is delivered through a special catheter with deployable electrodes at the tip; the electrodes touch the vein walls and deliver energy directly into the tissues without coagulating blood. The newest system, called ClosureFast, delivers infrared energy to vein walls by directly heating a catheter tip with radiofrequency energy. Published results show a high early success rate with a very low subsequent recurrence rate up to 10 years after treatment. Early and mid range results are comparable to those obtained with other endovenous ablation techniques. The authors' overall experience has been a 90% success rate, with rare patients requiring a repeat procedure in 6-12 months. Overall efficacy and lower morbidity have resulted in endovenous ablation techniques replacing surgical stripping. Patient satisfaction is high and downtime is minimal, with 95% of patients reporting they would recommend the procedure to a friend (56-58).

**Figure 5.** A diagram shows the technique of RFA for varicose veins .A. The catheter is inserted and advanced into the diseases vein through a small incision into the diseased vein under ultrasound guidance. B Then laser or radiofrequency energy is applied to the lining of the vein, heating and shrinking the vein walls, causing them to seal and as the catheter withdrawn the vein is closed

procedure is now known with 10 years of experience (54-55).

Other diseases where ablation is used include cardiac catheter thermal ablation is now standard of care for a variety of cardiac arrhythmia types (irregular heart beat rhythm). Techniques are directed at cauterizing areas of high irritability that give rise to frequent ectopy and trigger paroxysmal atrial fibrillation (PAF), or cauterisation of the substrate that maintains PAF, (predominantly left atrial tissue), or both. Usually this is done with radiofrequency energy delivered percutaneously by steerable catheters. In the UK, recent Guidance from NICE approved catheter ablation for PAF on the NHS for patients who have failed treatment with two antiarrhythmic drugs. Similar guidelines exist in the USA. Success rates of 70-80% can be achieved, with multiple procedures being needed in many cases. RFCA for PAF carries significant risks. These are; stroke (<1%), cardiac tamponade (2-6%), pulmonary vein stenosis (0.5-1%), a small risk of arteriovenous fistula (<0.5%), and a very small but important risk of oesophago-atrial fistula. In older patients, (>70 years), patients with structural heart disease and patients with persistent or prolonged AF, there is significantly less chance of success with RFCA. Recently an electro-anatomic mapping systems" (a form of mini-"GPS", or "Sat-Nav" system), are becoming increasingly sophisticated at telling an electrophysiologist exactly where a catheter is within the heart, and exactly where anatomical structures are located relative to it. This is important for avoiding complications. A CT Scan or MRI scan of heart chambers is useful for obtaining the detailed anatomy of the heart for RFCA procedures (59-61).

RFA of the AV-junction followed by implantation of a pacemaker provides good control of symptoms, reduced drug and healthcare consumption, and reduced hospital admissions. However, AV-junctional ablation is not reversible, and allows atrial fibrillation to continue, albeit without allowing it to produce rapid, irregular ventricular rates, so that patients may be unaware of being in PAF. RFA of the AV-junction followed by implantation of a pacemaker is increasingly reserved for patients with established/chronic AF in whom ventricular rate-control cannot be achieved with AV-nodal blocking drugs. In these patients AF persists in spite of treatment anyway, and RFA of the AV-junction with permanent pacing can give excellent symptom control (NICE 2006) (62).
