The Pathology of TRI-Tech Leaflet Escape.
Marialuisa Valente, Mila Della Barbera, Annalisa Angelini, GianDomenico Cresce, Massimo Montisci, Gaetano Thiene. University of Padua, Medical School, Padova, Italy; San Bortolo Hospital, Vicenza, Italy
Background: The TRI-Tech valve is a low-profile mechanical bileaflet valve prosthesis with a rotating pivot system. Leaflet escape due to pivot fracture was reported and the implantation program interrupted worldwide. The fracture was ascribed to pivot height asymmetry.
Design: To assess whether the asymmetry was an isolated defect or intrinsic to other commercialized TRI-Tech valves, 3 TRI-Tech valves with leaflet dislodgement implanted in 3 patients (pts) two in aortic and one in mitral position and 150 unimplanted TRI-Tech valves, 19-31 mm in size, were studied. Both the pts with aortic escape died suddenly at 10 days and 39 months after surgery and the escaped emidisc was found in the thoracic aorta and in the left common iliac artery, respectively. The pt with mitral leaflet escape had a cardiogenic shock at 22 months, was successfully reoperated and the escaped leaflet was found in the left common iliac artery. Tab height and asymmetry measurement (Δ between tab heights from the leaflet base) was performed in all cases.
Results: In all the escaped discs one pivot disappeared, fractured at the base, thus explaining leaflet dislodgment from the hinge and its distal escape. Small thrombus deposition was observed within the hinge of the fractured tab in the aortic patient who died suddenly at 40 months from reoperation.The asymmetry was over 0.35 mm in all (0.55 and 0.40 mm in the aortic, and 0.46 in the mitral prostheses), and the fracture involved the lower tab in 2 and the higher tab in one. The asymmetry was observed in all unimplanted valves was less than 0.08 mm in 69 (46%), in between 0.08 and 0.20 in 66 (44%), 0.20 to 0.35 mm in 14 cases (9%), and over 0.35 mm in one case. Only in one out of 150 unimplanted valves the asymmetry was as high as observed in the fractured clinical valves.
Conclusions: Asymmetry was present in all unimplanted valves, however, in only one device it was of such size as observed in failing devices. This means that pivot fracture occurred when the height asymmetry was particularly severe. The more the asymmetry the early the fracture occurrence. Pivot rupture with leaflet escape was rarely reported in other valve models. The TRI-Tech quality control did not foresee pivot symmetry check. Since tolerance for pivot asymmetry is unknown and risk of rupture unpredictable, interruption of implant program with prophylactic replacement of implanted TRI-Tech valve was judicious.
Wednesday, March 2, 2011 1:00 PM
Poster Session VI # 39, Wednesday Afternoon