A novel coaptation plate device for functional mitral regurgitation: an in vitro study

Comparative Study of Single Opening&Closing and Continuous Pulsatile Flow Valve Tester

PURPOSE

The purpose is to demonstrate the difference in closing volume fraction between the single opening&closing valve tester (SOCVT) and continuous pulsatile flow valve tester (CPFVT).

METHODS

A comparative study was conducted in four hemodynamic conditions selected from the ISO 5840 on the four mitral valve states: normal annulus, 40% annulus dilation, 60% annulus dilation, and repaired valve with a clip device in both the SOCVT and CPFVT. The closing volume fractions were compared and errors calculated in the 16 cases.

RESULTS

In the CPFVT, the flowrate waveform depends more on hemodynamic conditions rather than the valve morphology. For closing volume fractions in the two testers, twelve cases had errors between 10% and 20% and 3 cases had errors between 2.2% and 5.5%. There was no statistic difference in the closing volume fraction between the CPFVT and SOCVT for the normal annulus, 40% valve annulus dilation, 60% valve annulus dilation and repaired valves (P values = 0.44, 0.44, 0.33, and 0.08, respectively, n = 4).

CONCLUSION

There is certain error in closing volume measurements, even if no statistic difference in closing volume measured by the SOCVT and CPFVT. The typical flow waveforms of the mitral valve may be available to standardize testing of the SOCVT to evaluate valve hemodynamics. The SOCVT may be an alternative to the valve testing.

A Single-opening&closing Valve Tester for Direct Measurement of Closing Volume of the Heart Valve

PURPOSE

The objective of this study was to develop a novel single opening&closing pulsatile flow in-vitro valve tester for direct measurement of closing volume of the heart valve.

METHODS

A single opening&closing valve tester was composed of a piston pump, valve mounting chamber, reservoir, measurement and control system. The piston pump was used to drive a valve to open and close with dictated flow which comprised three phases of accelerated, constant, and decelerated flow with six slopes. A high speed camera was used to record valve opening and closing images. Two pressure transducers across the tested valve were used to capture the ending time of valve closing which was verified by the high-speed photography. The closing time was measured and closing volume was calculated with a piston displacement volume during valve closing. A tilting disc valve and porcine mitral valve were tested.

RESULTS

There was a big difference in flowrate between the Transonic flowmeter and piston pump. The heart valve opened and closed under the dictated flow driven by the piston pump. The transvalvular pressure was minor during valve opening and then increased sharply during valve closing. The closing time varied approximately linearly with the slope of the decelerated flow and was comparable between the two methods by the transvalvular pressure and high-speed photography. The closing volumes did not change much with the slope of the decelerated flow and were 7.0 ± 1.0 and 14.0 ± 1.5 mL for the tilting disc valve and mitral valve, respectively.

CONCLUSION

Pulsatile flow is challenging to the flowmeter. A novel single opening&closing pulsatile flow in-vitro valve tester for the heart valve has successfully been developed and can be used to simulate and evaluate the opening and closing hemodynamics of the heart valve. The tester can be used to measure valve closing volume and time accurately with a standardized testing protocol free from effect of other components such as the resistance, compliance units and auxiliary valve in the continuous pulsatile flow valve tester.

Transapical Coaptation Plate for Functional Mitral Regurgitation: An In Vitro Study

A novel transapical coaptation plate (TCP) device was developed and anchored by sutures in the mitral valve to treat functional mitral regurgitation. The objective of this study was to test efficacy of the TCP in an in vitro model. Eight fresh porcine mitral valves were mounted in a left heart simulator to simulate functional mitral regurgitation by means of annular dilatation and asymmetrical or symmetrical papillary muscle (PM) displacement. Six polyurethane TCPs in thickness of 6.4(#1), 4.8(#2), 3.2(#3) mm and hardness of durometer 30 A (H) and 30 OO(S),were fabricated and labeled as H1, H2, H3 and S1, S2, S3, respectively. These TCPs were anchored by the sutures in the mitral annulus and left ventricle apex, and tested. Steady backward flow leakage in a hydrostatic condition and regurgitant volume in a pulsatile flow were measured before and after implantation of the TCPs. Mean regurgitant volume fractions in the asymmetric PM displacement were reduced significantly from 59.1 to 37.2% for H1, 43.2% for H2, 35.9% for S1 and 34.2% for S2 (p < 0.021), after implantation of the TCPs. No significant reduction in mitral regurgitation was seen for H3 and S3 (p > 0.067). Mitral regurgitation was mild in the symmetric PM displacement, and was not significantly reduced after implantation of the TCPs. In conclusion, the TCP anchored by the sutures in the mitral annulus and left ventricle apex functions successfully as a plug in the mitral valve leaflet gap. The TCP with thickness equal to or greater than 4.8 mm is effective to reduce functional mitral regurgitation. The TCP hardness has no effect on difference in reduction of functional mitral regurgitation.