Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field.

The present treatment of atrial fibrillation by radiofrequency catheter ablation requires long continuous lesions in the thin walled left atrium where side effects may lead to serious complications. Better understanding of the physical processes that take place during ablation may help to improve the quality, safety, and outcome of these procedures. These processes include the distribution of power between blood, tissue, and patient; the mechanisms of tissue heating and coagulum formation; the relation between tissue and electrode temperatures; and the effects of increased electrode size and internal and external electrode cooling. With normal electrode-tissue contact, only a fraction of all power is effectively delivered to the tissue. Due to the variability of blood flow cooling, applied power and electrode temperature rise are poor indicators of lesion formation. With a longer electrode, the efficiency of tissue heating is decreased and the greater variation in tissue contact caused by electrode orientation makes lesion formation even more unpredictable. The absence of impedance rise during ablation does not guarantee the absence of blood clot formation on the tissue contact site. Blood clots may unnoticeably be created on the lesion surface and are caused by thermal denaturization of blood proteins, independent of heparinization. Irrigated ablation with external flush may prevent blood clot formation. Irrigation minimally affects lesion size by cooling the tissue surface. Larger lesions may only be created by the application of higher power levels. Electrode cooling, however, impedes electrode temperature feed back and blinds the operator for excessive tissue heating. External cooling alone with preservation of temperature feed back is a promising concept that may lead to improved procedural safety and success.

Background-Electrode

The smaller electrode resulted in transmission of a greater fraction of the radiofrequency power to the tissue and resulted in higher tissue temperature, larger lesions, and lower dependency of lesion size on the electrode orientation.