In vitro investigation on opening angle and hydrodynamic performance of four bileaflet valves in mitral position

AbstractMitral regurgitation (MR) occurs with a prevalence of approximately 10 % in patients aged 75 years or older and therefore is one of the most frequent indications for heart valve surgery. During the last decade surgical mitral valve repair (MVR) procedures emerged as the gold standard for the treatment of clinically relevant MR. However, for surgically inoperable or high-risk patients transcatheter-based MVR devices present a valuable treatment option. Within the current study, we developed an experimental setup to investigate the hydrodynamic performance of transcatheterbased MVR devices in vitro. The bicuspid mitral valve (MV) model employed in the experimental setup features a D-shaped MV annulus with d1 = 26.30 mm, d2= 30.05 mm and chordae tendineae with a length of l1= 25 mm attached to two papillary muscle structures. Pressure gradient - volumetric flow rate (Δp-Q) relations were investigated for steady state backward flow with transvalvular pressure gradients ranging from 0.75 mmHg ≤ Δp ≤ 103.13 mmHg. Deionized water at 37 °C with a dynamic viscosity of 1.002 mPa∙s and a density of 998 kg/m3 was used. A test-chamber consisting of a press-fit MV holder and cylindrical in- and outflow tracts were developed. Different designs for the exchangeable press-fit MV holder were manufactured using additive manufacturing technologies providing an optimal fitting for variable MV sizes and pathologies. In- and outflow tracts featuring a diameter of d = 50 mm and a height of h = 60 mm were made from transparent polymethylmethacrylate to allow for easy optical access during measurements. The experimentally investigated Δp-Q relation yields a quadratic correlation for the open MV and a linear correlation for the closed MV. A transvalvular closing pressure of (4.94 ± 0.04) mmHg was measured for the MV model.

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In Vitro Hydrodynamic Characteristics Among Three Bileaflet Valves in the Mitral Position

Artificial Organs ◽

10.1046/j.1525-1594.2000.06498.x ◽

2000 ◽

Vol 24 (5) ◽

pp. 346-354 ◽

Cited By ~ 15

Author(s):

Zhonggang Feng ◽

Mitsuo Umezu ◽

Tetsuo Fujimoto ◽

Toshiya Tsukahara ◽

Masakazu Nurishi ◽

...

Keyword(s):

Hydrodynamic Characteristics ◽

Mitral Position ◽

Bileaflet Valves

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In Vitro Hydrodynamics of Four Bileaflet Valves in Mitral Position

Asian Cardiovascular and Thoracic Annals ◽

10.1177/021849230000800102 ◽

2000 ◽

Vol 8 (1) ◽

pp. 3-10 ◽

Cited By ~ 1

Author(s):

Zhong Gang Feng ◽

Mitsuo Umezu ◽

Tetsuo Fujimoto ◽

Toshiya Tsukahara ◽

Masakazu Nurishi ◽

...

Keyword(s):

Pressure Drop ◽

Orifice Diameter ◽

Opening Angle ◽

Positive Pressure ◽

Closing Volume ◽

In Vitro Test ◽

Jude Medical ◽

Carbomedics Valve ◽

Bileaflet Valves

Hydrodynamics of St. Jude Medical, Carbomedics, Advancing The Standard, and On-X bileaflet valves with an annular diameter of 25 mm were obtained using an in-vitro test system. Steady flow studies demonstrated different pressure drops due to differences in valve design, particularly the geometric orifice diameter and the opening angle. The On-X valve produced the least pressure drop, whereas the Carbomedics valve had the greatest pressure drop. In pulsatile flow experiments, the On-X and St. Jude Medical valves consistently produced the lowest mean positive pressure gradients, while the Carbomedics valve had the highest gradients. In spite of its parallel leaflets design, the On-X valve showed a closing volume as small as that of Carbomedics valve. The results indicate that a larger orifice diameter and greater opening angle can significantly reduce transvalvular pressure loss. This study also demonstrated that attempts to improve the hydrodynamic efficacy of the On-X valve were successful in reducing the pressure gradient as well as maintaining a low closing volume.

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