November 1, 2023Catheterization and Cardiovascular Interventions7 citations

Right ventricular outflow tract obstruction associated with neointimal tissue accumulation and distortion of the Harmony TPV25 stent frame: Potential mechanisms and treatment

ZSZachary L. Steinberg ACAllison K. Cabalka DBDavid T. Balzer

Structured PICO

Does valve-in-valve implant improve hemodynamics in patients with Harmony TPV25 transcatheter pulmonary valve obstruction?

Population

6 patients who underwent reintervention for Harmony TPV25 transcatheter pulmonary valve dysfunction (obstruction with peak catheterization gradient 28-73 mmHg) 10-28 months after initial implant.

Intervention

Valve-in-valve implant using balloon expandable transcatheter valves

Outcome

Final peak gradient and regurgitation after valve-in-valve implant, and description of stent frame distortion and tissue accumulationsurrogate

Valve-in-valve implantation with balloon-expandable valves effectively treats short-term Harmony TPV25 dysfunction caused by frame distortion and tissue accumulation.

Abstract

BACKGROUND: The Harmony TPV25 transcatheter pulmonary valve (Medtronic Inc.) is constructed with a self-expanding stent frame comprising six zigged nitinol wires sewn together and covered with knitted polyester fabric, with flared inflow and outflow ends and a porcine pericardial valve sutured to the central portion of the device. It was approved for treatment of pulmonary regurgitation after prior right ventricular outflow tract repair in 2021. Early outcomes of this procedure have been excellent, but little is known about valve durability or ultimate mechanisms of dysfunction. METHODS: We collected data on patients who underwent reintervention for TPV25 dysfunction and described findings related to distortion of the stent frame and tissue accumulation. RESULTS: We describe six patients who underwent valve-in-valve implant for TPV25 obstruction (peak catheterization gradient peak 28-73 mmHg) 10-28 months after implant. In all cases, there was tissue accumulation within the inflow and valve-housing segments of the device and deformation of the self-expanding valve frame characterized by variable circumferential narrowing at the junction between the valve housing and the inflow and outflow portions of the device, with additional geometric changes in all segments. All six patients underwent valve-in-valve implant that results in a final peak gradient ≤10 mmHg and no regurgitation. DISCUSSION: The occurrence of short-term Harmony TPV25 dysfunction in multiple patients with a similar appearance of frame distortion and tissue accumulation within the inflow and valve housing portions of the device suggests that this may be an important failure mechanism for this valve. Potential causes of the observed findings are discussed. It is possible to treat this mechanism of TPV25 dysfunction with valve-in-valve implant using balloon expandable transcatheter valves.

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