Physiologic effects and functional outcome after treatment of dysfunctional right ventricular outflow tract in congenital heart disease using a two-stage intervention

Pathophysiological differences in relief of pulmonary stenosis (PS) as opposed to pulmonary regurgitation (PR) by percutaneous pulmonary valve implantation (PPVI) remain elusive, but might impact current assessment of procedural success and ultimately indications.

Invasive pressure measurements, cardiac magnetic resonance imaging and cardiopulmonary exercise testing were performed before pre-stenting (BMS), after BMS and after PPVI in patients with either PS or PR.

In PS (n = 14), BMS reduced the right ventricular (RV) to systemic pressure ratio (0.8 ± 0.2 vs. 0.4 ± 0.1%; p < .01), improved RF EF (53 ± 14 vs. 59 ± 12%; p = .01) but introduced free PR (PR fraction post 39 ± 12%; p < .01) with no changes in effective RV stroke volume (SV). PPVI eliminated PR (PR fraction 5 ± 3%; p < .01) and improved effective RV SV (p < .01) with no changes in RV EF (p = .47). Peak VO2 improved significantly after BMS, with no changes following PPVI (26 ± 9 vs. 30 ± 11 vs. 31 ± 10 ml/kg*min). In PR (n = 14), BMS exaggerated PR (PR fraction post 47 ± 10) with reduction in effective RV SV (pre 43 ± 9 vs. post 38 ± 8 ml/m²; p = .01), which improved after PPVI (post PPVI 49 ± 9 ml/m²; p < .01), secondary to elimination of PR (PR fraction 5 ± 4%; p < .01). RV EF (pre 53 ± 11 vs. post 53 ± 9 vs. post PPVI 50 ± 9%) and Peak VO2 (pre 22 ± 7 vs. post 21 ± 7 vs. post PPVI 23 ± 7 ml/kg*min) remained unchanged.

Exercise capacity in patients with right ventricular outflow tract dysfunction is primarily afterload-dependent.