A novel trileaflet mechanical heart valve: first in vitro results.

Objectives: Heart valve prostheses are the therapy of choice for patients with severe heart valve diseases. Two types of prostheses that can be implanted in patients are available: biological and mechanical. Though mechanical heart valves have some disadvantages like necessity of life-long anticoagulation, biological heart valve prostheses often necessitate reinterventions due to limited durability. Therefore, a new trileaflet mechanical heart valve was developed, featuring hinges in the systolic flow with the aim of function and thrombogenicity.

Methods: We first compared the new trileaflet mechanical heart valve to conventional bileaflet heart valves (St. Jude Medical and On-X valves) in vitro. Haemodynamic measurements were performed in a pulse duplicator system, and clot formation was examined with an implemented method using enzyme-activated milk as the test medium.

Results: Haemodynamic measurements showed the largest effective orifice areas and smallest pressure gradients for the trileaflet prosthesis compared to the bileaflet valve. Opening and closing characteristics of the trileaflet valve and of the St. Jude Medical valve were comparable. Clotting tests depicted only minor isolated deposits for the new trileaflet valve whereas the bileaflet valves showed distinct clots in the area of the hinge in all experiments.

Conclusions: Haemodynamic and clotting tests showed improvements for the new trileaflet valve compared to common bileaflet valves. The off-wall systolic position of the hinges, which eluded adverse flow areas, was a major advantage of the new valve.