Chronic Intravascular Hemolysis Following Cardiac Replacement With the St. Jude Medical Prosthesis: Comparative Study With the Bjork — Shiley Prosthesis

This study compares 153 patients with SJM prosthetic valves and 37 patients with Björk-Shiley valves for evidence of intravascular hemolysis and analyzes the degree of hemolysis by position (mitral or aortic), diameter, number of pros theses and duration of implant.

The hematological status of all the patients was assessed by the following laboratory tests: hemoglobin concentration, serum lactatedehydrogenase (LDH), red blood cells count (RBC) , reticulocytes, serum iron, serum haptoglo bin, hemosiderinuria and schistocytes count.

The results of laboratory tests and the characteristics of implant were com pared by the Pearson X² for qualitative variables and by the analysis of covari ance, using the regression approach, for continuous variables.

This study indicates a significantly higher degree of hemolysis in the St. Jude Medical group as shown by LDH and haptoglobin values which are the most reliable sources revealing qualitative hemolysis.

The relationship between hemolysis, duration of implant, diameter, number and position of the prostheses, inside the SJM group, shows significance only between hemolysis and number of prostheses.

Furthermore, the data show a higher degree of hemolysis in the mitral posi tion for SJM prosthesis and in aortic position for Björk-Shiley (B-S) prosthesis.

The explanation for this difference may be the turbulent flow of regurgitant leakage at the pivots recesses in the SJM valve which is higher in the mitral position where there is the maximal pressure gradient and the asynchronous closure of the two leaflets.

The authors conclude that, in spite of the higher degree of hemolysis shown by the SJM prosthesis, there is no reason to revaluate its use because no case of clinically significant hemolytic anemia was observed in this study.