Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease resulting in long-term right ventricular (RV) failure, ventricular arrhythmias and sudden cardiac death. Our team validated a swine chronic model of repaired TOF (r-TOF) and characterized several levels of ventricular detrimental remodelling. We aimed to evaluate the potential reversibility of this structural remodelling following percutaneous pulmonary valve implantation (PPVI).

Significant pulmonary regurgitation, mild stenosis and RV outflow tract scars were created in 21 piglets. Subsequently, 12 animals underwent PPVI at different time intervals using the Melody® valve. Ventricular remodelling was evaluated by TTE, MRI, ventricular optical mapping, histological and biomolecular study.

Initial results showed a significant RV hypertrophy on MRI with a prolongation of RV activation time beyond the surgical scar and the LV in rTOF models compared to sham-models. Four animals died during PPVI procedure. Among survival animals, the valvular function was excellent, and a significant decrease in RV volume was observed on MRI evaluation. Regarding the first ex vivo results, a significant RV hypertrophy together with a prolongation of RV activation time (APD80) beyond the surgical scar and the LV was found in r-TOF control animals while a limitation of the prolongation of APD80 beyond RVOT and LV has been observed in PPVI pigs. Subsequent experiments (including electrophysiological and biomolecular study) are currently undertaken.

The creation of a swine survival r-TOF model mimicking the essential features of postoperative TOF, and its subsequent pulmonary valve replacement, is feasible. PPVI so far appears to have a beneficial effect on RV hypertrophy and ventricular electrophysiological disturbances, suggesting potential reversibility on ventricular remodelling after this targeted therapy.