RF ablation has an established record of successfully treating a variety of arrhythmias. With RF ablation, precisely focused radiofrequency energy (low-voltage, high-frequency electricity) passes between the catheter tip and the heart tissue, effectively burning small, targeted areas of heart tissue, creating a scar. This damaged tissue is no longer capable of generating or conducting electrical impulses thereby preventing the arrhythmia from being generated.
There are many different RF catheters available that make it possible for the cardiologist to access certain sites inside the heart. Once the RF catheter is in the selected position within the heart, it only takes a minute to make a burn (lesion). Given the procedure may continue for up to 4 hours, this is an important consideration.
Currently, RF ablation is the primary treatment for heart-racing problems. Clinical trials found an overall success rate using RF ablation of 90 - 95%, while about 5% of patients required a second try because of recurrence.
Cryoablation is carried out using hollow catheters (Freezor catheters) and cooled, thermally conductive, circulated fluids. During the procedure, a pressurized refrigerant liquid (nitrous oxide or N2O) travels in an ultra-fine tube to the tip of the catheter. The liquid refrigerant vaporizes as it is sprayed into the tip. As it vaporizes, it absorbs heat from the surrounding tissue, thereby cooling and freezing the target tissue. The warmed refrigerant is vacuumed back and out of the system.
Cryoablation is an effective and safer way of treating younger patients with heart rhythm problems where there might be a risk of damaging the conduction system with RF ablation such as AV node re-entry tachycardia or in all patients with high risk of atrioventricular node (AV node) injury such as para-nodal arrhythmias.
While cryocatheters stick tightly to the heart muscle and do not move like RF catheters, clinical trials show success rate of treating patients with common types of heart racing to be 85%. While croyablation allows the cardiologist to free tissue to test whether it is responsible for heart racing, as the tissue can be rewarmed to restore its function, with RF ablation, once the tissue is burned, it stays burned. Using cryoablation, the time it takes to make a comparable lesion is several minutes, compared to 60 seconds using RF ablation. There is a higher chance of recurrent arrhythmia - approximately 15% with cryoablation and due to the longer "burn time", the procedures take longer.