Bioprosthetic heart valves: modes of failure

Abstract

Valve replacement started in 1960, with the surgeon now having a significant variety of prosthetic heart valves from which to choose. These valves are broadly divided into mechanical heart valves (MHV) and bioprosthetic heart valves (BHV). Improvements in the performance and ease of usage of BHV without the need for anticoagulant therapy are among the desired features of BHV and hence the increasingly preferred choice over their mechanical counterparts. However, with increased use the post-implantation complications have become more apparent, and these include: calcification, cusp tears, pannus growth, infective endocarditis, valve thrombosis and other factors specific to valve type. In this review we describe these complications in order to bring awareness among surgeons, clinicians and pathologists. Diagnosis, treatment and preventive measures, if taken in a timely manner, can help reduce their impact and further enhance the quality of life of patients with prosthetic heart valves.

Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

“…Patient's own valve was taken from one site (pulmonary) and implanted at another site, for example, pulmonary valve grafted into the aortic site. This predominately occurs in children with diseased native aortic valves [2].…”

“…Other findings were calcification, pannus, thrombus, and mononuclear cells and macrophages on the cusp surface (Figures 2 and 13). The high rate of para-stent post cuspal tears, thickening, and tissue degeneration is due to high mechanical stress [2,9] and abrasion-related damage at this point ( Figure 7). The Mitroflow pericardial valves are prone to early calcification because of lack of antimineralization treatment [9].…”

“…A Dacron fabric covers the entire stent and a sewing skirt is fashioned and attached to the base of the wire 2 ISRN Biomaterials stent. Contemporary models of these valves are durable and last for 10-15 years [2].…”

“…Tears are commonly seen at the commissure and around the stent post due to high stress aggregation at these sites and collagen degeneration [2]. They are commonly seen associated with calcification, though the calcification at the margins of tears could be a secondary phenomenon, occurring after the tear [23] (Figure 7).…”

“…The aortic root, valve, and proximal ascending aorta are fixed, cleaned, sized, mounted on a stent if needed, and packaged (and cryopreserved in the case of homografts). Today, most tissue valves are also treated with antimineralisation agents, to reduce tissue calcification [2,5]. BHF failure may occur due to general causes, that is, factors common to all valves or to factors specific to each particular device.…”