Hydrodynamic Assessment of Aortic Valves Prepared from Porcine Small Intestinal Submucosa

Abstract

Infants and children born with severe cardiac valve lesions have no effective long term treatment options since currently available tissue or mechanical prosthetic valves have sizing limitations and no avenue to accommodate the growth of the pediatric patient. Tissue engineered heart valves (TEHVs) which could provide for growth, self-repair, infection resistance, and long-term replacement could be an ideal solution. Porcine small intestinal submucosa (PSIS) has recently emerged as a potentially attractive bioscaffold for TEHVs. PSIS may possess the ability to recruit endogenous cardiovascular cells, leading to phenotypically-matched replacement tissue when the scaffold has completely degraded. Our group has successfully implanted custom-made PSIS valves in 4 infants with critical valve defects in whom standard bioprosthetic or mechanical valves were not an option. Short term clinical follow-up has been promising. However, no hydrodynamic data has been reported to date on these valves. The purpose of this study was to assess the functional effectiveness of tri-leaflet PSIS bioscaffolds in the aortic position compared to standard tri-leaflet porcine bioprosthetic valves. Hydrodynamic evaluation of acute PSIS function was conducted using a left heart simulator in our laboratory. Our results demonstrated similar flow and pressure profiles (p > 0.05) between the PSIS valves and the control valves. However, forward flow energy losses were found to be significantly greater (p < 0.05) in the PSIS valves compared to the controls possibly as a result of stiffer material properties of PSIS relative to glutaraldehyde-fixed porcine valve tissue. Our findings suggest that optimization of valve dimensions and shape may be important in accelerating de novo valve tissue growth and avoidance of long-term complications associated with higher energy losses (e.g. left ventricular hypertrophy). Furthermore, long term animal and clinical studies will be needed in order to conclusively address somatic growth potential of PSIS valves.

Effect of valve leaflet surface patterning on valve hydrodynamic performance

“…This hemodynamic parameter can be used for evaluation of the closing performance of the valve. 9 Many factors affect the amount of regurgitation. Therefore, in addition to testing the percentage of the regurgitation of each valve at different flow rates, ISO also recommends testing conditions with different reverse pressures and different heart rates at a fixed physiological cardiac output of 5 L/min to evaluate the effects of reverse pressures and heart rates on regurgitation.…”

Biological Scaffolds for Congenital Heart Disease

“…Furthermore, the explanted intracardiac patches displayed calcification, elastic fibres, eosinophils, no infiltration of host cells, and inhibited remodelling of the cardiac tissue after 21 months of implantation. In another study, four infants suffering from CHD valvular defects received personalised porcine SIS tri-leaflet valves [119]. A short-term clinical follow-up based on haemodynamic assessment (TEHV scaffolds vs. standard porcine bioprosthetic valves) revealed comparable flow and pressure profiles, despite significantly higher forward flow energy losses exhibited by the engineered valves.…”

After 50 Years of Heart Transplants: What Does the Next 50 Years Hold for Cardiovascular Medicine? A Perspective From the International Society for Applied Cardiovascular Biology

“…Early clinical successes have been noted in pediatric mitral valve repair using constructs of porcine small intestinal submucosa handmade in the clinic to resemble valve leaflets (78). The ad hoc use of this material in patients with few other clinical options has yielded promising results in short-term clinical follow-ups and work by recruiting endogenous cells that stimulate leaflet remodeling and growth (79, 80). Similar strategies are being developed for aortic valve replacement.…”