Suture dehiscence and collagen content in the human mitral and tricuspid annuli

Abstract

Post-operative suture dehiscence is an important mode of short-term mitral and tricuspid valve (MV, TV) repair failure. We sought to evaluate suture pullout forces and collagen density in human atrioventricular valves for a better understanding of the comparative physiology between the valves and the underlying mechanobiological basis for suture retention. Mitral and tricuspid annuli were each excised from hearts from human donors age 60-79 with no history of heart disease (n=6). Anchor sutures were vertically pulled until tearing through the tissue. Suture pullout force (F P ) was measured as the maximum force at dehiscence. Subsequently, tissue samples from each tested suture position were evaluated for collagen content using a standard hydroxyproline assay. Among all mitral positions, no significant differences were detected among positions or regions with mean F P values falling between 6.9±2.6N (posterior region) and 10.3±4.7N (anterior region). Among all tricuspid positions, the maximum and minimum F P were 24.0±9.2N (trigonal region), and 4.5±2.6N (anterior region). Although for the MV, a given sample's collagen content had no correlation to its corresponding F p , the same relationship was significant for the TV. Further, the TV exhibited comparable F P to the MV overall, despite a nearly 40% reduction in collagen content. These findings suggest that sutures placed in the trigonal region of the TV have higher pullout force than those placed along other segments of the annuli. Furthermore, there are likely differences in collagen orientation between the mitral and tricuspid annuli, such that collagen content strongly impacts F P in one, but not the other.

Use of Computational Fluid Dynamics to Analyze Blood Flow, Hemolysis and Sublethal Damage to Red Blood Cells in a Bileaflet Artificial Heart Valve

“…Incidences of hemolysis do occur due to obstruction of a leaflet by formation of a thrombus or pannus [20,21]. Failure of a suture with the valve pulling away from the surrounding tissue, dehiscence, is yet another problem [22] leading to hemolysis. While clinical studies show a prevalence of subclinical hemolysis (with a low incidence of hemolytic anemia or clinically severe hemolysis) in valve replacement patients [23][24][25], current in-vitro and CFD research into hemolysis damage are still measuring and predicting damage to RBCs from notable amounts of hemolysis caused by artificial heart valves [26][27][28][29].…”