What is Hemolytic Anemia associated with mechanical damage to red blood cells?
Mechanical destruction of red blood cells in prosthetic blood vessels or valves of the heart. It is likely that the basis of this form of anemia is the mechanical injury of red blood cells due to the sharp compression of small blood vessels. Mechanical hemolytic anemia was observed in hemolytic-uremic syndrome, malignant hypertension, metastatic cancer, angiosarcoma.
For the first time in 1954, hemolytic anemia was described in patients with an aortic valve prosthesis. In 1961, a patient is described with acute erythrocyte destruction after plastic surgery to restore the interatrial septum with Teflon. I had to resort to re-operation, which established a patient with mitral valve insufficiency. During systole, the blood enters the Teflon septum with the area devoid of endothelium. On this site was a small bag, probably causing blood turbulence. During the second operation, the bag was sutured and the teflon bare area was covered with endothelium, after which the signs of increased red blood cell destruction disappeared. Since that time, there have been many reports of acute hemolytic syndrome after a similar operation.
According to the literature, the most frequent acute hemolytic anemia occurs in cases of aortic valve replacement. Hemolytic anemia, which developed 8 hours after surgery, is described. In other cases, the destruction of red blood cells developed only a few days or even weeks after surgery. Sometimes hemolytic anemia developed after mitral valve replacement.
Diagnosis of Hemolytic Anemia associated with mechanical damage to red blood cells
The degree of anemia may be different depending on the severity of the process of destruction of red blood cells. There are changes in the shape and size of erythrocytes, polychromasia (the ability to be stained with both basic and acidic dyes). Often found signs of fragmentation of red blood cells, there is a large number of triangular red blood cells, schizocytes (fragments of red blood cells), red blood cells with spikes. Hypochromia of erythrocytes and a decrease in color index associated with prolonged loss of iron in the urine are possible. The number of leukocytes and platelets in most cases within the normal range. The content of bilirubin is somewhat elevated. Serum iron content is normal or slightly reduced. It is possible that in case of mechanical trauma, various serum proteins, including immunoglobulins, are sometimes nonspecifically fixed on the altered erythrocyte membrane.
Thus, the main factor in the mechanism of the development of acute hemolytic anemia in patients undergoing heart surgery and prosthetics is the mechanical destruction of red blood cells when in contact with the surface of the prosthesis. Undoubtedly, not only the treatment of the prosthesis and the material from which it is made play a role, but also hemodynamic conditions: blood flow velocity in the area of the prosthesis, the formation of vortices.
Diagnostics is based on:
- on the data of the anamnesis;
- detection of red blood cell fragments and a large number of schizocytes in smears;
- on signs of intravascular erythrocyte destruction (such as an increase in plasma free hemoglobin, urine hemosiderin, an increase in serum LDH as a result of the release of an enzyme from red blood cells).
In a patient with mechanical hemolytic anemia, the life expectancy of a transfused red blood cell of a healthy person is sharply shortened. Such a study is more informative than determining the life expectancy of a patient’s own erythrocytes. Its shortening may be due to various reasons, whereas the shortening of the life span of erythrocytes of a healthy person is associated with mechanical destruction, if the serum does not contain allo- or autoantibodies to the erythrocytes of the donor.
Treatment of Hemolytic Anemia associated with mechanical damage to red blood cells
Symptomatic treatment; with severe hemolytic anemia, red blood cell transfusions are shown, sometimes repeated surgery. Mild hemolytic anemia does not require treatment, its symptoms gradually decrease. With symptoms of iron deficiency anemia, iron therapy is recommended.