A method of using the pulmonary trunk to form a trileaflet valve

Abstract

Materials and Methods Human anatomic study. Using cadavers (n 7), the main pulmonary trunk was removed and trimmed to create a tissue cylinder with a height equal to the corresponding aortic annulus diameter (Figure 1, A). Three longitudinal incisions, 2 mm less than one half the cylinder height, were positioned 120° apart (Figure 1, A). The resulting flaps were involuted and secured 2 to 3 mm from the superior rim of the cylinder with 6-0 polypropylene (Prolene; Ethicon, Inc, Somerville, NJ) sutures passed through adjacent flaps near their free edges and tied, making each a U stitch (Figure 1, B-D). The base of the involuted tissue was joined with additional 6-0 polypropylene sutures, creating interleaflet triangles and eliminating acute corners from the inner surface of the valve (Figure 1, E). The outermost wall was scalloped (Figure 1, D and E). Implantation was performed with a subcoronary, modified freehand method (Figure 1, F and G). After removal of the native leaflets, stay sutures were passed through the aortic annulus at a position corresponding to the midpoint of each excised leaflet. These were placed through the construct at the superior cut edge (as opposed to the base of the valve in the freehand method), and the construct was lowered into position (Figure 1, F). A 6-0 polypropylene suture was run along the superior aspect of the construct’s outermost wall, following the commissural pillars’ contours (Figure 1, G). Passive testing of each valve’s competency was performed under a 200 mm Hg saline column, enabling endoscopic inspection of the neoleaflets. One aortic root was positioned in a flow simulator, and transvalvular pressure gradients were determined across a range of flows (1-6 L/min, 0.9% saline). Sheep study. The valve design was tested in an adult sheep model (n 2). Before each operation, a replacement valve derived from the pulmonary trunk of a donor sheep was passively tested. The valve constructs were implanted as aortic valve replacements in the subcoronary position by the modified freehand technique described previously (Figure 1, F and G). After weaning from cardiopulmonary bypass, the valves were examined with an epicardial echocardiography probe. Regurgitant flow was determined by continuous-wave Doppler scanning in the long-axis view. Peak velocity was obtained in the one animal in which anatomic alignment of the probe allowed measurement. All animals received humane care in compliance with the “Guide for the Care and Use of Laboratory Animals” prepared by the Institute of Laboratory Resources, National Research Council.