Biological heart valves

Abstract

Cardiac valvular pathologies are often caused by rheumatic fever in young adults, atherosclerosis in elderly patients, or by congenital malformation of the heart in children, in effect affecting almost all population ages. Almost 300,000 heart valve operations are performed worldwide annually. Tissue valve prostheses have certain advantages over mechanical valves such as biocompatibility, more physiological hemodynamics, and no need for life-long systemic anticoagulation. However, the major disadvantage of biological valves is related to their durability. Nevertheless, during the last decade, the number of patients undergoing biological, rather than mechanical, valve replacement has increased from half to more than three-quarters for biological implants. Continuous improvement in valve fabrication includes development of new models and shapes, novel methods of tissue treatment, and preservation and implantation techniques. These efforts are focused not only on the improvement of morbidity and mortality of the patients but also on the improvement of their quality of life. Heart valve tissue engineering aims to provide durable, "autologous" valve prostheses. These valves demonstrate adaptive growth, which may avoid the need of repeated operations in growing patients.

Iranian homograft tissue processing

“…Heart valve disease has devastating consequences and is burdensome for patients and health systems. Roughly 300,000 heart valve replacements are performed globally in a year 13 , 14 . All kinds of valve replacements come with an associated number of complications and drawbacks.…”

Antibody formation towards porcine tissue in patients implanted with crosslinked heart valves is directed to antigenic tissue proteins and αGal epitopes and is reduced in healthy vegetarian subjects

“…1 Along with mechanical valve prostheses, bioprosthetic heart valves, which are derived from porcine or bovine tissue, are frequently implanted. 2 For more than 50 years, a method has been established that both helps to preserve the tissue and reduces the natural immunogenicity of theses valves, namely the fixation of the tissue with glutaraldehyde. Aldehydes chemically react with free amino groups and therefore crosslink tissue proteins which is assumed to destroy or mask immunogenic epitopes within the tissue.…”

The choice of cryopreservation method affects immune compatibility of human cardiovascular matrices

“…The ability to replace tissues on demand would help to decrease the mortality rate in many clinical scenarios. Off-the-shelf available vascular grafts and heart valves for example would be needed for bypass surgery 1 , 2 , cardiac valvular pathologies including rheumatic fever, atherosclerosis in elderly patients or congenital malformation in children 3 – 6 , shunts for dialysis patients 7 , 8 and vessel reconstruction after organ transplantation 9 , 10 . Therefore, improved strategies and techniques for tissue preservation have to be developed to tackle this urgent and so far unmet medical need 11 .…”

“…Biological vascular and heart valve matrices appear to be beneficial compared to synthetic or mechanical substitutes with respect to hemodynamic features, biocompatibility, anti-coagulation treatment, and their potential to grow and remodel especially in young patients 4 , 6 , 12 . However, the availability of human biological matrices for an off-the-shelf allogeneic application is limited.…”