Novel Pressure-Regulated Deployment Strategy for Improving the Safety and Efficacy of Balloon-Expandable Transcatheter Aortic Valves

Abstract

Objectives: The authors propose a novel pressure-regulated method for balloon-expandable transcatheter heart valve (THV) deployment, aimed at optimizing prosthesis-annulus apposition while preventing significant tissue injury.

Background: The optimal method for balloon-expandable THV deployment remains debated. Current protocols are volume dependent, relying on under- and overfilling of the deployment apparatus. During deployment, the annular wall tension exerted by the expanding prosthesis is determined by maximal THV diameter and balloon pressure (Laplace's law).

Methods: Three hundred thirty consecutive patients with severe native aortic stenosis who underwent TAVR with SAPIEN 3 THVs were included. One hundred and six patients were considered at high risk for annular rupture. THVs were deployed until reaching a predetermined balloon pressure. Postdilatation was performed to reduce mild or greater angiographic paravalvular regurgitation (PVR). Using a biomechanical model, annular wall stress was estimated for each case and assessed against rates of postdilatation, mild or greater PVR on transthoracic echocardiography, new permanent pacemaker placement or left bundle branch block, and annular rupture.

Results: Patients with wall stress >3 MPa had reduced postdilatation rate (P < 0.001) and reduced final PVR (P = 0.014). Annular rupture occurred in 2 of 3 high-risk patients with wall stress >3.5 MPa (3.69 and 3.84 MPa); no rupture occurred in 95 high-risk patients with wall stress ≤3.5 MPa. We defined a single target deployment pressure per THV size to ensure deployment within target wall stress levels of 3 to 3.5 MPa: 6.25 atm for 23-mm THVs, 5.5 atm for 26-mm THVs, and 5 atm for 29-mm THVs. Patients within this target range (n = 136) had a 10.0% postdilatation rate, 12.7% mild PVR, and no moderate to severe PVR. The relationship between balloon filling volume and associated pressure and wall stress was inconsistent.

Conclusions: Pressure-regulated THV deployment is a simple, reproducible, safe, and effective method, regardless of high-risk anatomical complexities.

Keywords: TAVR; aortic stenosis; transcatheter heart valve.