Erythrocyte damage observed in patients with heart valve replacement: Investigation by morphological, biochemical and hemorheological techniques

Current sophisticated open heart surgical technologies have improved the prognosis of patients undergoing heart valve repair and replacement. Optimal antithrombotic strategy is now established using antiplatelet and anticoagulant agents, whereas subclinical erythrocyte damage caused by prosthetic heart valves is drawing less attention. Therefore, the aim of this study is to investigate the erythrocyte damage in prosthetic heart valve recipients from several viewpoints of serum biochemistry, erythrocyte morphology, and clinical hemorheology. Serum lactate dehydrogenase level was elevated significantly (p = 0.007) in patients with metallic heart valves (n = 6) but not in those with bioprosthetic heart valves (n = 8) as compared with healthy controls (n = 8). In the microscopic examination, teardrop cells, fragmented cells, and erythrocyte with local membrane protrusion (so-called budding) were observed in some patients with metallic heart valve replacement but not in the other two groups. Erythrocyte filterability estimated by our specific gravity filtration technique showed significant intergroup difference at low filtration pressure (50 cmH₂O) (p < 0.001), but not at high filtration pressure (100 cmH₂O). Therefore, damage to the erythrocyte by prosthetic heart valves is evident from morphologic, biochemical, and hemorheological perspectives. These findings indicate that damaged erythrocytes may have rheological impact at low shear rate condition reflecting the complicated relationship between structure and function of erythrocyte membrane regulating wholecell deformability in concert.