Catheter-delivered cryoablation in the pediatric coronary sinus: assessing newer arrhythmia therapies.

摘要

Cryothermal (Cryo)-energy tissue delivery, utilizing handheld probes, was the mainstay of arrhythmia surgery throughout thel980s, becoming the "gold standard," with success rates better than pharmacologic therapy of the time. However, the surgical nature of the procedure itself with need for open thoracotomy, cardiopulmonary bypass, and combination skills and cooperation between the electrophysiologist and surgeon, often with custom-fabricated epicardial "mapping" electrodes, made this a long and tedious intervention, and not without typical surgical morbidities. In this regard, the evolution of effective radiofrequency (RF) catheter delivery systems was seen as an advantage in arrhythmia intervention associated with less comorbidities, even in children. However, RF energy application intrinsically is associated with technical limitations. Lesions are relatively deep, with large areas and volume, potentially causing adverse collateral tissue damage. The inherent capability of cryoablation to first "map" a potential arrhythrnogenic site by reversible extracellular cooling with high temperatures (0degC to -15degC) has distinct advantages over RF applications. With Cryo, if the reversible thermal application is found to be effective and safe, lower tissue temperatures to -70degC can then be applied, associated with production of a permanent lesion by intracellular disruption of organelles and cell membranes. A comparable analogy is the difference between applying an ice cube and dry ice. This reversing capability is absent with RF and has made Cryo technology ideal for application in smaller hearts and any arrhythrnogenic substrate close to the normal conduction tissue. In addition, the potential for less collateral damage makes its application attractive in preventing vascular damage. The evolution of catheter from hand-probe cryoablation delivery technology during the 1990s has now extended its use from the operative field into catheter-ization laboratory. Although perhaps more utilized in older patients than children, catheter-delivered cryoablation is currently becoming part of the standard ablative technologies for various arrhythmias in Pediatric Electrophysiology centers. The application of this technology into the coronary sinus of children, however, is still an evolving concept.