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INTRODUCTION

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Definition

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  • 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.

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Clinical Features

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  • 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).

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Laboratory Features

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  • 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.

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Table Graphic Jump Location
TABLE 20–1SEVERITY OF PROSTHETIC VALVE HEMOLYSIS
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Diagnosis

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  • 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.

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Treatment

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  • 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.

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MARCH HEMOGLOBINURIA AND SPORTS ANEMIA

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Definition

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  • First described in a German soldier in whom hemoglobinuria was brought on by marching.

  • Also seen in young athletes with frequent participation in severe and prolonged exertion.

  • Hemoglobinuria has also been ...

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