Chapter 20: Traumatic Hemolytic Anemia, March and Sports-Related Hemoglobinuria, Traumatic Cardiac Hemolytic Anemia

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.

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 ...