Effect of the Implantation Angle on the Durability of a Bio-Prosthetic Pulmonary Valve in the Tetralogy of Fallot

BACKGROUND AND OBJECTIVES: Tetralogy of Fallot (TOF) patients require pulmonary valve replacement (PVR) after total correction to prevent the late complications associated with pulmonary valve dysfunction. This study aimed to evaluate factors affecting the durability of bio-prosthetic pulmonary valves, with an emphasis on the angle of implantation as well as age, size or materials of prosthetic valve. METHODS: Of the 50 consecutive patients with TOF who underwent redo-PVR due to prosthetic valvular failure (PVF) between January 2001 and May 2020, 36 had good images for measuring implantation angle on computed tomography, magnetic resonance imaging, or angiography. We defined the angle of implantation as the angle between an imaginary axial line from the center of the prosthetic valve and an imaginary parallel line from the point where the line meets the anterior wall of main pulmonary artery on sagittal planes. RESULTS: The median age at total repair of TOF was 13.4 months (interquartile range [IQR], 8.4-22.3 months) and the median age at initial PVR was 10.1 years (IQR, 8.4-12.2 years). The mean interval from initial PVR to redo-PVR was 10.1±3.6 years and follow-up duration was 15.6±2.5 years after initial PVR. The implantation angle (<30° or ≥45°) was significantly related with early (<10 years after PVR) PVF. CONCLUSIONS: The risk for early PVF was relatively lower when the implantation angle was between 30° and 45°. We should be careful to implant a prosthetic valve with an adequate angle to maintain a laminar flow in the pulmonary position for better durability.