Radiofrequency ablation is successful in treating some but not all arrhythmias. With non irrigated technology it has been difficult to ablate ischemic VT. This may be due to an inadequate lesion size. Irrigated electrodes were developed to create larger lesions. Open irrigation at the catheter tip not only produces larger lesions, but also helps reduce the risk of coagulum (clots) and charring due to high temperatures.