Right ventricular outflow tract landing zone perimeter / circularised diameter - new imaging standards in pulmonary valve replacement reporting.

Background: Right ventricular outflow tract intervention spans transcatheter, surgical, or hybrid pulmonary valve replacement methodologies. Standardised pre-procedure workup includes cardiac MRI to identify an intended valve site (landing zone). Our institutional practice includes measurement of the right ventricular outflow tract perimeter (circumference) of this site in end-systole. Our primary aim was to compare patients by their perimeter values to the palliative interventions performed (transcatheter versus surgical/hybrid methodologies).

Methods: Retrospective review of patients undergoing pulmonary valve replacement from January 2017 to 2021. We performed perimeter measurements at the intended valve site on advanced imaging; the outcomes of interventions were outlined via descriptive and statistical analyses.

Results: A total of 37 patients underwent pulmonary valve replacement that met study criteria - 21 transcatheter, 7 surgical, and 9 hybrid. Median age at intervention was 26 years (range 8-70). The mean end-systolic perimeter of the transcatheter cohort was 88.9 ± 8.7 mm and in the surgical/hybrid cohort measured 106.6 ± 7.5 mm. For the transcatheter cohort, the median "circularised" diameter derived from the perimeter measurement (divided by π) was 27.7 mm (range 24.3-32.4). Notably, this correlated (r = 0.93, p < 0.01) with the median diameter of the narrowest region during actual transcatheter right ventricular outflow tract balloon sizing (lateral imaging) of 27.1 mm (range 23.2-30.1).

Conclusions: Right ventricular outflow tract perimeter measurement to determine circularised diameter is useful in planning pulmonary valve replacement in terms of candidacy of transcatheter versus the need for a surgical/hybrid approach. The circularised diameter correlates with transcatheter right ventricular outflow tract balloon sizing.