Radiofrequency ablation is a medical procedure in which defined areas of tissue are destroyed by high-frequency currents as a result of heat exposure. The procedures are mainly used to destroy metastases in the liver and to treat atrial fibrillation. Radiofrequency ablation can be performed minimally invasively via catheter and is therefore particularly gentle. It can be repeated as needed for recurrent problems.
What is radiofrequency ablation?
Radiofrequency ablation is also known synonymously as radiofrequency or thermal ablation. Through an applicator or catheter, electrodes are placed in close proximity to the tissue to be destroyed and heated by a high-frequency current of about 460 to 480 kilohertz. The power consumption at the electrodes, despite different competing systems, is usually around 200 watts. The exposure to heat creates relatively sharply defined areas of destroyed tissue (heat necrosis), which can be further degraded by the body’s own metabolism and, in the case of obliteration in one of the atria, loses its electrical conductivity and electrical initiation potential. Radiofrequency ablation is usually performed using minimally invasive techniques. This offers the advantage of repeatability in case of unsatisfactory results or recurrent problems. Significantly less valuable functional liver tissue is removed when targeting metastases to the liver compared with conventional surgical procedures.
Function, effect, and goals
Radiofrequency ablation is mainly used in two completely different fields of application. On the one hand, it is used in oncological applications, mainly to combat metastases, and on the other hand, it is a cardiological treatment method for so-called atrial fibrillation. In cancer medicine, thermoablation is used less for the destruction of a primary tumor than for the necrotization of metastases, if the primary tumor belongs to the class of tumors that can metastasize. There is extensive experience for the destruction of metastases in the liver and vertebral bodies – usually as adjunctive therapy to chemotherapy and radiotherapy. However, no scientific studies exist to demonstrate any advantages of radiofrequency ablation over open surgical procedures. In principle, the main advantage of minimally invasive destruction of metastases metastasized in the liver by thermal ablation is believed to cause less damage to intact liver tissue than open surgical procedures. In surgical procedures, it is inevitable that more functionally healthy liver tissue will be removed than is the case with radiofrequency ablation. The goal of ablation in oncology is to prevent metastases from growing further and cause them to die. When radiofrequency ablation is used in cardiology, the aim is not so much to destroy tissue as to permanently alter the electrophysiological properties of certain cardiac muscle cells so that they cannot transmit or generate electrical stimuli to contract the atria. Atrial fibrillation, which is relatively common in the elderly, usually results from myocardial cells in the left atrium near the junction of the pulmonary veins transmitting uncoordinated electrical signals emanating from the pulmonary veins, causing the atria to contract arrhythmically and very rapidly. In doing so, they ignore the electrical impulses emitted by the sinus node, the main pacemaker in the right atrium. The goal of radiofrequency ablation to combat atrial fibrillation is to render the myocardial tissue around the junctions of the pulmonary veins electrically inactive. This is roughly equivalent to electrically isolating the orifices of the pulmonary veins in the left atrium (pulmonary vein isolation). While the goal of thermoablation in oncology is the destruction of diseased tissue (metastases), the goals of radiofrequency ablation for the treatment of atrial fibrillation are the sustained electrophysiological alteration of principally healthy cardiac muscle cells. The particular advantages of minimally invasive thermal ablation over surgical intervention lie in the repeatability of the ablation in the event of insufficient results or the formation of recurrences.Radiofrequency ablation for atrial fibrillation is contrasted with so-called cryoablation, in which ablation is achieved by the application of cold rather than heat. The main advantage of cryoablation over thermal ablation is that the tissue in question can be precooled during cryoablation. The electrophysiological effects can then be measured and verified. If the expected effect does not occur, the procedure can be aborted, and after temperature adjustment, the tissue is fully functional again.
Risks, side effects, and hazards
The direct risks associated with minimally invasive radiofrequency ablation to combat metastases are considered to be very low. They are lower than those of a conventional surgical procedure. The greatest “risk” is that the intended goals are not achieved with the first treatment or that recurrences appear. In most cases, thermoablation can then be repeated without any problems. The treatment of atrial fibrillation by radiofrequency ablation, for example in the left atrium, is also considered to be of low risk. However, higher technical risks are present because, for example, planned electrical isolation of the pulmonary veins requires a catheter to be advanced into the right atrium via a groin vein and then to penetrate the septum between the two atria to reach the left atrium near the junctions of the four pulmonary veins. The main risks with this procedure are not so much in performing the ablation as in maneuvering the cardiac catheter to the site of insertion in the left atrium. Possible complications can arise from blood clots forming, which can cause thrombotic events, and in injury to the pericardium or esophagus. Also, severe bleeding may occur at the site of entry of the cardiac catheter into the inguinal vein. Above risks of injury are minimized if the procedure is performed by an experienced physician.
