Mechanical PVR is associated with a limited risk of valvular thrombosis. Thrombolysis was an effective treatment in the majority.

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Objective: Hinge washing is a crucial factor in the prevention of mechanical prosthetic valvar thrombosis, especially in the pulmonary valve position. The aim of this laboratory study was to determine the relationship between pressure difference and the amount of hinge washing in the closed position, using the pressures that are normal for the right ventricle and pulmonary artery. Methods: In an in vitro setting, four different bileaflet mechanical valves were tested for hinge washing in closed position. Based on similarity in inner diameter (range: 20.5-21.4 mm), the following valves were tested: Abbott SJM Regent size 23, Cryolife On-X size 23, LivaNova Carbomedics-R size 25, Medtronic Open Pivot (M-OP)-A size 25. Tests were carried out in a range between 3 and 100 mm Hg pressure difference, using water as a test fluid. The amount of leakage per minute through the closed valve was measured. Results: All four valves showed an increase in leakage with increasing transvalvar gradient, and the relationship between pressure and leakage behaves in logarithmic fashion. Leakage under normal pulmonary diastolic pressure conditions (10 mm Hg) was between 23.3% and 29.3% of the leakage under aortic diastolic pressure conditions (80 mm Hg). The Cryolife On-X valve showed the highest closed leakage volume under pulmonary conditions (10 mm Hg) 0.254 + 0.01 (L/min), where the Medtronic MOP showed the lowest leakage volume with 0.125 + 0.014 (mL/min). Conclusion: Hinge washing is related to transvalvar pressure difference in closed position. Valve brands differed significantly from each other in the amount of hinge washing.

In this thesis the prosthetic heart valve in the pulmonary position has been analyzed. The results in this thesis demonstrate that there is a need for a suitable valve for the pulmonary position, tailored to the physiological circumstances of the right ventricle and the young age of this population. Currently available valve types each have its own limitation that tend to be more prone in the pulmonary position. We have demonstrated that a mechanical prosthetic valve can be a suitable option for pulmonary valve replacement. furthermore, we have demonstrated that the hemodynamic conditions in which the valve is placed influence the functionality of valve. Our results showed that the quality of life of congenital heart disease patients with a prosthetic valve is comparable to the general population. Overall, we can conclude that the use of prosthetic valves in the pulmonary valve is suboptimal, while life expectancy increases and in particular the Quality of Life of patients with a pulmonary prosthetic valve does not seem to be affected.