Adverse results of a decellularized tissue-engineered pulmonary valve in humans assessed with magnetic resonance imaging

OBJECTIVES: Matrix P (R) and Matrix P plus (R) tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology. METHODS: Between June 2006 and August 2008, 17 Matrix P (R) and 10 Matrix P plus (R) TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required. RESULTS: Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V-max = 3.7 +/- (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 +/- 3%) and stenosis with moderate-to-severe insufficiency (V-max = 3.5 +/- 0.8 m/s, RGF = 38 +/- 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case. CONCLUSIONS: The high frequency of Matrix P (R) and Matrix P plus (R) graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.