The aortic valve blood supply.
OBJECTIVE
Normal valves are known to be metabolically active, yet the route of oxygen delivery is unclear. Although diffusion from the valve surface is the presumed source, the presence, distribution and importance of the aortic valve's vascular bed is unclear.


METHODS
Seventeen porcine hearts (51 cusps) were obtained at slaughter. The coronary circulation was pressure-rinsed with a heparin solution and filled with an Aquablack solution at physiological pressure. The cusps were subsequently dissected and fixed for viewing with an inverted microscope. The anterior leaflet of the mitral valve was evaluated as a control for the vessel filling protocol. Using Adobe Photoshop and captured images, whole cusps were reconstructed, a grid was overlaid and vascular distribution evaluated.


RESULTS
Of the 15 porcine aortic valves that filled, 32/45 (71%) of the cusps contained vessels. Nine valves had vasculature in all three cusps and two valves were completely avascular. Vessels were found predominantly in the basal third of the cusps and extended in from the commissures almost to the level of the free edge. There was a statistically significant difference (p<0.001) between the appearance of vessels in the basal region and in the mid and free edge regions of the valve. No difference in vascularization pattern was noted between the left, right or non-coronary cusps.


CONCLUSIONS
The presence of a vasculature suggests that the metabolic activity of the cusp is greater than can be supported by diffusion from the cusp surface alone. The absence of functioning vessels might explain the failure associated with cryopreserved implants and may play a role in the durability problems faced by bioprosthetic valves. It will also be important to consider the role of this intrinsic circulation with the advent of tissue-engineered valves.
Weind
K L
KL
The Heart Valve Laboratory, Robarts Research Institute, London, Ontario, Canada.
Ellis
C G
CG
Boughner
D R
DR
D000818:Animals; D001021:Aortic Valve / Q000033:anatomy & histology*; D003326:Coronary Circulation; D008833:Microcirculation; D013552:Swine