Yao, Junke; (2024) Sizing and Stabilising Valvuloplasty Balloon Catheters Using a Robotic Inflation Device. Doctoral thesis (Ph.D), UCL (University College London).

Text PhD_Thesis_JunkeYao.pdf - Accepted Version Access restricted to UCL open access staff until 1 January 2026. Download (78MB)

Abstract

Aortic stenosis, a common heart valve disease, restricts blood flow due to the stiffening and thickening of aortic leaflets, preventing proper valve opening. Transcatheter aortic valve implantation (TAVI) offers a minimally invasive replacement of the diseased valve via a catheter, with balloon aortic valvuloplasty used beforehand to dilate the valve. However, balloon inflation during interventions can be unstable due to pulsating blood flow and heart contractions, risking malposition or cardiac arrest. Rapid ventricular pacing (RVP) mitigates this but can cause transient hypotension during inflation. Additionally, preoperative imaging for sizing has limitations, potentially causing complications. This thesis presents a novel approach to enhancing commercially available valvuloplasty balloon catheters by integrating stabilization and sensing functions through a robotic inflation platform. The key contribution is the development of a synchronized balloon dilatation mechanism and the aortic valve dimension estimation to avoid the need for RVP. This achieves safe, adequate balloon inflation and deflation during diastole for balloon stable and improves the selection of prosthetic aortic valve sizes. Numerical modelling evaluates the impact of varying inflation levels on positional instability caused by pulsating blood flow, guiding the design of the robotic platform for precise inflation and deflation control. The platform also acquires intra-balloon pressure-volume data, enabling an innovative intra-operative aortic annulus sizing method. Experimental validation using aortic root phantoms with different calcification patterns compared valve opening area and transvalvular pressure with conventional BAV, resulting in improved dilatation performance. The intra-operative annular sizing method uses a sizing algorithm to accommodate compliance and geometric irregularities and achieves accurate diameter estimation. High-speed synchronized dilation and intra-operative sizing simultaneously enhance the precision of TAVI device selection, reducing the reliance on RVP. Comprehensive simulations and experiments demonstrate significant progress towards autonomous stabilization of valvuloplasty balloon catheters and improved TAVI device selection for compliant aortic annuli with complex geometry.

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