Medical Engineering & Physics vol:32 issue:8 pages:934-939
Objective: Mechanical heart valves carry the disadvantage of lifelong antithrombotic therapy, due to the high risk of thrombus formation on the valve surface. Current diagnostic methods are incapable of detecting thrombus formation in an early stage. Our aim is to develop a diagnostic method, based on the analysis of the acoustic signal produced by the valve. This method should be capable of early detection
of malfunction, thus permitting targeted medication and reducing valve related complications and mortality.
Methods: A measurement setup assuring optimal signal quality was developed, and a software program automating temporal and frequency analysis of the signal was implemented. The method and program were first validated on an in vitro mock circulatory loop. Next, three sheep were implanted with a St. Jude Regent bileaflet valve and one with an Advantage valve. The signal of their valve undergoing thrombosis was assessed on weekly basis before explantation. The four sheep were sacrificed shortly after the first detection of malfunction according to the newly
developed method. Different criteria to proceed to explantation were used in the four cases.
Results: In each case thrombus or membrane formation was detected on the leaflets upon explantation, which was in accordance with the analysis results that had predicted a certain level of malfunctioning.
Conclusions: Acoustical analysis of mechanical heart valves permits early detection of valvular malfunction. Temporal analysis is a more straightforward method than frequency analysis, but its detection capabilities are slightly less sensitive. Further research with more in vitro and animal testing is required to statistically validate these findings.