Different Tilting Disc Valves Show Similar Rotation-Dependent Impairment in Hemodynamic Performance under a Tilted Implantation Position[1]

Abstract

Background: Aortic annulus calcification can promote tilted implantation of mechanical valves. This study evaluates the hemodynamics of tilting disc valves under this condition. Methods: 23 mm and 25 mm Ultracor® (UC) and Medtronic-Hall-Easy-Fit® (MH) valves were investigated in a pulse-duplicator under physiological conditions. Mean pressure gradient (dP_mean), systolic energy loss (dW_sys), effective orifice area (EOA), closure (V_Cl), leakage (V_L), and total regurgitation volume (V_R) were assessed. Valves were independently positioned at five axial rotations (0 - 180°, zero defined as major orifice facing the top of the “tilt-ramp”) and three tilt angles (0°, 10°, 20°) by lifting the prosthesis in the noncoronary sinus. Results: Diameter-enhanced MH valves exhibited a better systolic performance but a higher regurgitation than corresponding UC valves. Moderate tilting showed a rotation-independent increase in dP_mean and dW_sys and a decrease in V_R and EOA with no fundamental differences between valve types. Further tilting caused small additional changes at 90 - 180° rotation. At 0° rotation, however, dramatic regurgitation occurred throughout. Conclusion: Tilting worsened systolic performance regardless of valve type. It should therefore be avoided. Due to extensive regurgitation at 0° rotation, this position should be corrected whenever tilting is inevitable.

Heart valves - aortic valve - tilting disc valve - valve replacement - hemodynamics - pulsatile flow - cardiovascular physiology - cardiovascular models

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1 Presented at the annual meeting of The German Society for Thoracic and Cardiovascular Surgery in Hamburg, Germany, 13 - 16 February 2005.