Pathologic evaluation of 28 Mitroflow pericardial valves: a 12-year experience

Mitroflow pericardial valves (model A12) are used for aortic valve replacement with favorable hemodynamic results, and are ideal for patients with a small aortic annulus as the pericardium is mounted outside the stent frame. We report the morphologic findings in explanted Mitroflow valves from our institution and demonstrate pathologic changes leading to explantation.

From 2001 to 2013, 28 Mitroflow valves were analyzed at our institution. Demographic data was recorded. The excised valves were analyzed by gross and microscopic examination. After pathologic examination, mode of failure was determined.

During the 12-year period, 28 valves were explanted. The 28 patients, with a mean age at implant of 72.2 ± 5.7 years (range, 60 to 81 years), included 16 males (57%). The mean interval between index surgery and explantation was 4.5 ± 3.4 years (range, 3 months to 11 years). Structural valve deterioration was seen in 18 (64%) patients; mean age at implantation was 72.1 ± 5.69 years with an implant duration of 6.25 ± 2.6 years. Findings in patients with structural valve deterioration included cusp thickening (n = 18), tears (n = 17), pannus deposition (n = 17), and calcification (n = 14). Nonstructural valve deterioration and endocarditis was seen in 1 (4%) and 7 patients (25%), respectively. One valve explanted at post mortem did not contribute to the patient's death.

Structural valve deterioration was seen in 18 of 19 explanted valves with implant durations of at least 30 months, and is related to valve design. It appears that clinicians should carefully consider Mitroflow valve implantation in all patients, even in patients older than 65 years old, given the early presence of structural valve deterioration.