Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ INTRODUCTION +++ Definition ++ Also referred to as macroangiopathic hemolytic anemia, a type of fragmentation hemolytic anemia. Complications of prosthetic heart valves (or less commonly cardiac valve disorders, especially severe aortic or subaortic stenosis) or other mechanical cardiac devices, such as left ventricular assistance devices. Turbulence and high shear stresses within a space enclosed by a foreign surface result in red cell fragmentation and hemolysis. +++ Clinical Features ++ Patients with ball-and cage valves, bileaflet valves (as compared to tilting disc valves), mechanical valve prostheses versus xenograft tissue prostheses, and double-valve as compared to single-valve replacement are more likely to experience clinically significant hemolysis. Hemolytic anemia is usually mild and compensated but may be severe. Coexistent other causes of anemia (iron or folate deficiencies, see Chaps. 8 and 9), and increased cardiac output as a consequence of strenuous physical exertion, can convert mild hemolysis without anemia to moderate or severe hemolysis and a more severe anemia resulting from increased shear stress. More important clinically is the thrombogenicity of nonendothelialized surfaces, as well as the loss of nitric oxide-mediated reduction in platelet reactivity and vasodilation, which promote platelet thrombosis and embolization (see Chapter 19). +++ Laboratory Features ++ Blood film: moderate poikilocytosis, schistocytosis, and polychromasia may be present (see Table 20–1). Serum levels of total and indirect bilirubin, and LDH can be elevated, whereas the serum haptoglobin is depressed. Urine hemosiderin present as a result of intravascular hemolysis. Iron deficiency may result from chronic hemoglobinuria and hemoglobinuria. Decreased platelet count may indicate platelet thrombi on valve surfaces. ++Table Graphic Jump LocationTABLE 20–1SEVERITY OF PROSTHETIC VALVE HEMOLYSISView Table||Download (.pdf) TABLE 20–1 SEVERITY OF PROSTHETIC VALVE HEMOLYSIS Mild Moderate Severe Hemosiderinuria Present Present Marked Hemoglobinuria Absent Absent Absent Schistocytosis < 1% > 1% > 1% Reticulocytosis < 5% > 5% > 5% Haptoglobin Decreased Absent Absent LDH < 500 Units/L > 500 Units/L > 500 Units/L LDH, lactic acid dehydrogenase.Source: Williams Hematology, 8th ed, Chap. 50, Table 50–2, p. 759. +++ Diagnosis ++ Based on the presence of schistocytes on the blood film and evidence of chronic intravascular hemolysis in a patient with a cardiac valve disorder or an artificial heart valve or cardiac device. +++ Treatment ++ Appropriate therapy is to replace iron and folate (if deficient). Surgical repair or replacement of the malfunctioning prosthesis (if indicated). Transfusion may be necessary preoperatively and may diminish the rate of hemolysis by decreasing the heart rate and flow velocity. For severe anemia ineligible for reoperation, recombinant human erythropoietin treatment may diminish or eliminate transfusion requirements. +++ MARCH HEMOGLOBINURIA AND SPORTS ANEMIA +++ Definition ++ First described in a German soldier in whom hemoglobinuria was brought on by marching. Also seen in young ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth