was performed on two of the failed heterograft valves and three control pig valves. Failure of the heterograft was due to stretching and deformation of the cusps with resultant valvular incompetence. Stretching of the cusp was a result of reduction in the amount of its collagen content. The elastic tissue appeared little altered. A microscopic layer of fibrin thrombus was present on the surface...

OBJECTIVES The purpose of this study was to investigate the expression of angiotensin II (Ang II)-producing enzyme systems in normal and stenotic aortic valves. BACKGROUND Chronic inflammation and fibrosis are involved in the pathogenesis of aortic stenosis (AS), but the detailed molecular mechanisms of this atherosclerosis-like process remain obscure. Angiotensin II, a powerful mediator of i...

BACKGROUND Glutaraldehyde-treated bioprosthetic heart valves are commonly used for replacement of diseased heart valves. However, calcification and wear limit their durability, and the development of new and improved bioprosthetic valve designs is needed and must be evaluated in a reliable animal model. We studied glutaraldehyde-treated valves 6 months after implantation to evaluate bioprosthet...

BACKGROUND The mechanisms of extracellular matrix changes accompanying myxomatous valvular degeneration are uncertain. METHODS AND RESULTS To test the hypothesis that valvular interstitial cells mediate extracellular matrix degradation in myxomatous degeneration by excessive secretion of catabolic enzymes, we examined the functional characteristics of valvular interstitial cells in 14 mitral ...

BACKGROUND AND AIM OF THE STUDY The performance and longevity of bioprosthetic heart valves are limited by tissue calcification and degeneration after implantation. Experimental valve replacement in large animal models forms an important component of the preclinical evaluation of these bioprosthetic heart valves. The study aim was to assess the feasibility of a mitral model for stentless valves...

One hundred and fifty five patients with 167 bioprosthetic valves (68 Wessex porcine, 54 Hancock pericardial, and 45 low profile Ionescu-Shiley pericardial valves) were studied by Doppler ultrasound. Valve gradients were calculated from the mitral and aortic flow velocities by the modified Bernoulli equation. Mean mitral gradients were significantly smaller across the Ionescu-Shiley valves than...

Heterologous aortic valves are used in many clinics as replacements for diseased human aortic and mitral valves. These valves possess all the advantages of homologous aortic valves and are more easily available to the surgeon. The heterologous valve also provides a greater choice of valve size than does the homograft; this can be of importance when replacing the mitral valve. Hetero-graft valve...

The aim of the present study was to analyze if LDL particles trapped in stenotic aortic valve tissue undergo oxidative modification. Degenerative aortic stenosis affects >3% of the population >75 years of age in the Western world. Recent studies have revealed the presence of a chronic inflammatory process similar to what has been described in other degenerative diseases such as atherosclerosis....

Multipotent neural crest cells (NCCs) are a major extracardiac component of cardiovascular development. Although recognized as contributing cells to the arterial valves at early developmental stages, NCC persistence in the valves at later times or in the adult heart is controversial. We analyzed NCC persistence and contributions to both semilunar and atrioventricular (AV) valves in the mature h...