A Practical Model of Balloon/Tissue Contact in Pulmonary Vein Isolation with Cryoballoon Ablation

Effective treatment of paroxysmal atrial fibrillation with pulmonary vein isolation via cryoballoon ablation is dependent on effective contact with the targeted tissue surface. A computational method for determining contact area between the inflated cryoballoon and a given left atrial anatomy (including the pulmonary veins which return blood to the left atrium) was developed to evaluate the potential benefit of multiple balloon sizes in any left atrial anatomical shape acquired by medical imaging (e.g. X-ray computed tomography). The balloon geometry and material properties were obtained from 3D scanning and material testing of a commercial cryoballoon (POLARx™ FIT cryoballoon catheter, Boston Scientific). The tissue model consists of a primary continuous layer of elastic material conforming to the inside surface of the left atrium and a support array of massless, stiff surfaces conforming to the tissue shape and connected to linear spring elements. A sensitivity study shows robustness of model outputs (e.g. balloon/tissue contact area proximal edge location) to a relevant range of balloon and tissue model parameters. Application of the model to post-procedure comparison of contact area for two different balloon sizes based on cine and X-ray CT imaging is discussed. The balloon/tissue contact model provides a balance between realistic prediction of tissue deformation and model complexity, offering potential for near-real-time application to clinical procedure planning.