Background: Elevated plasma lactate dehydrogenase (LDH) concentration may reflect hemolysis due to mechanical heart valve dysfunction. Thus, knowledge of LDH levels in patients with properly working prostheses is required. Because hemolysis parameters for the SJM Hemodynamic Plus (HP) and Regent series are currently not available, the purpose of our study was to determine these data.
Methods: At 12-19 months follow-up after isolated aortic valve replacement with SJM HP(R) or Regent prostheses, we examined 102 patients by transthoracic echocardiography and determined plasma LDH, haptoglobin, bilirubin and hemoglobin.
Results: Five patients with properly working prostheses were excluded because of increased LDH due to non-cardiac reasons. In four patients with paravalvular leakage, LDH was 244, 307, 446 and 628 U/l, respectively. In patients with properly working prostheses, LDH was 287+/-52 (range: 163-374) U/l for HP(R) (n=33) and 274+/-48 (151-386) U/l for Regent valves (n=60, p=0.2). Haptoglobin was <1g/l in all patients; in 91% of HP and 75% of Regent valves, haptoglobin was below detection limit. Bilirubin and hemoglobin as well as red blood cell count (RBC) were normal in all patients except for five patients with renal anemia, two patients with paravalvular leakage and four patients with macrocytosis due to alcohol abuse. There was no correlation between LDH and transvalvular gradient (r=-0.02) or valve size (r=0.25).
Conclusions: In patients with SJM HP(R) or Regent valves in aortic position, LDH values > 400 U/l indicate valvular dysfunction or leakage if non-cardiac causes for hemolysis are excluded. However, paravalvular leakage can be present without substantially increased LDH. Haptoglobin has no diagnostic value as it is almost always markedly reduced. Hemolysis does not correlate with transvalvular gradient or prosthesis size.