Haemodynamic performance of the Medtronic Freestyle Porcine bioprosthesis in the pulmonary position in adult patients with corrected Tetralogy of Fallot

Objective: To assess the performance of the Medtronic Freestyle Porcine Stentless bioprosthesis following Pulmonary Valve Replacement (PVR) in patients with corrected Tetralogy of Fallot (TOF). Methods: A retrospective review was performed of 75 consecutive adult patients with a history of corrected TOF (65, 86.7%) or pulmonary atresia/VSD (10, 13.3%) undergoing PVR with the Medtronic Freestyle Porcine bioprosthesis from April 2008 to March 2014. Results: Mean age at reoperation was 33.4 ± 9.6 years, at a mean 29.8 ± 6.7 years following primary repair. Preoperative severe pulmonary regurgitation (PR) was present in 71(94.7) patients and mean preoperative Right Ventricular (RV) outflow tract gradients were 19.72mmHg. In addition to PVR, concomitant procedures were performed in 57(76%) patients, primarily right ventricular outflow tract augmentation (32, 42.7%). There was no 30-day mortality and no late deaths at a mean follow-up of 2.7 years. Echo at one year showed 97% of patients had no or trivial PR. Mean gradients between 12 -15mmHg were seen, with no significant differences between valve sizes from 21-29mm. RV end diastolic diameters reduced from pre op mean 4.06 ± 0.81cm to 3.37 ± 0.67 post op, p <0.001. RV end diastolic volume index measured on MRI reduced from mean 166.40 ± 37.09ml/m2 to 104.93 ± 21.89ml/m2 p=<0.001. Gradients and PR grade were not significantly changed at 4.7 years of echo follow up. Conclusion: The Medtronic Freestyle valve has low gradients at all valve sizes with minimal pulmonary regurgitation and substantial RV volume and diameter reduction. Further follow up will be required to assess its durability in the pulmonary position.