The in vitro hydrodynamic characteristics of the porcine pulmonary valve and root with regard to the ross procedure.
OBJECTIVE
The hydrodynamic parameters and leaflet motion of the porcine pulmonary root and valve and the performance of the pulmonary autograft implanted in subcoronary position or as a free-standing root were investigated at systemic and pulmonary pressures in vitro.


METHODS
Ten fresh pulmonary and aortic roots (anulus diameter, 20-25 mm) were tested in a pulsatile flow simulator. Five free-sewn pulmonary valves were implanted in aortic roots in the subcoronary position, and 5 pulmonary roots were implanted as free-standing roots. The external diameter of the roots was measured at the sinotubular junction in a pressure range of 0 to 120 mm Hg. The transvalvular gradient and regurgitation were measured, and the effective orifice area was calculated. The leaflet motion was recorded on video tape.


RESULTS
The fresh pulmonary roots were more compliant than their aortic counterparts (33% +/- 3. 0% vs 7% +/- 1.5% with dilatation at 0-30 mm Hg and 46% +/- 8.4% vs 35% +/- 7.8% with dilatation at 0-120 mm Hg). The pulmonary roots had a lower pressure drop at systemic than at pulmonary pressures. The pressure drops of the pulmonary roots were also lower than those of the aortic roots in the systemic pressure range. The leaflet opening of the pulmonary valve was triangular, with low bending deformation at all pressures. Implanting the free-sewn pulmonary valve in the subcoronary position or the pulmonary root as a free-standing root did not affect the hydrodynamic parameters and leaflet motion adversely.


CONCLUSIONS
The pulmonary valve and root could easily withstand aortic pressures in vitro. A biphasic dilatation curve ensures that higher pressures did not overdilate the pulmonary root. Moreover, valve performance was better at systemic pressures.
Yorkshire Heart Centre, Leeds General Infirmary, and the School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom.
Z L
ZL
Nagy
J
J
Fisher
P G
PG
Walker
K G
KG
Watterson
D000818:Animals; D001021:Aortic Valve / Q000502:physiology* / Q000601:surgery; D001696:Biomechanical Phenomena; D001705:Bioprosthesis; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D011664:Pulmonary Valve / Q000502:physiology* / Q000601:surgery; D011673:Pulsatile Flow; D013552:Swine; D014743:Videotape Recording