Valvuloplasty Balloon Catheter Sizing Approach for Calcified Aortic Valve with Different Annulus Ratios

Transcatheter aortic valve implantation (TAVI) is re- garded as the option of preference minimally invasive intervention to treat high-risk patients with aortic steno- sis, which is a common heart valve disease charac- terized by the narrowing of the valve opening due to the thickening of the valve leaflets. During TAVI, a prosthetic aortic valve, replacing the diseased native valve with its function, is inserted and expanded by a balloon catheter if it is a balloon-expandable device. As a result, the correct size of the prosthetic device is vital due to its association with potential complications such as paravalvular regurgitation and aortic annulus rupture [1]. Pre-operative annulus size measurement based on imaging techniques is commonly applied be- fore TAVI procedure including transthoracic echocar- diography, transesophageal echocardiography and multi- detector computed tomography [2], [3]. However, these techniques face two major limitations: heavy dependence on the operator’s experience and the influence of the optimum instant in the cardiac cycle for evaluation. In addition, the potential changes in the annular geometry caused by balloon aortic valvuloplasty, which uses a balloon catheter to dilate the calcified aortic leaflets as a bridge treatment to TAVI, are not considered. There- fore, intraoperative assessments based on valvuloplasty balloon catheters were introduced, which measure the annulus size by the balloon when it is inflated for dilatation [4]. They do, however, only provide limited compatibility for a limited number of devices. This study proposes an intra-operative method for mea- suring the aortic annulus that account for compliance and elliptical geometries using balloon internal pressure and volume data. The valvuloplasty balloon catheter from a commercially available source was used to obtain the intra-balloon pressure-volume curves by an inflation device. A characterized analytical model and a numeri- cal model for balloon free-inflation were used to develop a sizing algorithm for estimating annulus dimensions.