Analysis of sixty-two explanted Liotta bioprostheses: biocompatibility, biofunctionality, and biodurability issues

Sixty-two explanted Liotta porcine bioprostheses were examined to review the issues related to their biocompatibility, biofunctionality, and biodurability. These bioprostheses were harvested from 56 patients with implantation times ranging from only a few hours to more than nine years of implantation. There were 10 acute and short-term (< 1 year), 20 midterm (1 < t < 5 years), and 32 long-term (> 5 years) cases. The indications for the reoperations were: hemodynamic (59), thrombosis (10), and endocarditis (3). The major indications varied according to the duration of implantation: blood infiltration, fibrin buildup, thrombosis in the short-term; endocarditis and hemodynamic insufficiency in the midterm; and mineralization and tears causing hemodynamic incompetence in the long term. Mineralization proved to be the main threat to long-term durability for porcine valves. Besides a few short-term failures, these explanted devices slowly degenerated over time and were replaced to prevent congestive heart failure. Documentation of the failure modes of these porcine valves is important since the demand for bioprostheses will increase in the future, in particular for percutaneous devices. Such bioprostheses emphasize a critical biocompatibility issue following implantation because they have the capacity to remain free of thrombus in the absence of anticoagulation. The biofunctionality appears to be adequate in the absence of subsequent pathology with restoration of normal valve function. However, the documentation of such significant long-term biodurability issues raises questions that have been addressed but not fully answered yet with the new generations of bioprostheses.