Hemolysis in patients with the cloth-covered aortic valve prosthesis: Changing severity of hemolysis and prediction of anemia

Abstract

This paper is addressed to two questions: (1) Is there evidence for Increasing hemolysis in patients with a cloth-covered aortic valve prosthesis? (2) Is it possible to predict from the hematocrit, retriculocyte count, serum hemoglobin and serum lactic dehydrogenase (LDH) levels which patients are at risk of anemia? These screening studies were performed in patients attending the postoperative clinic from 1970 to 1973. Patients were classified into anemic and nonanemic groups. LDH values for the anemic group include all yearly values for that patient including preanemia levels. The median LDH levels showed a yearly increase in the anemic group and no change in the nonanemic group ( P < 0.005). A subset of these patients had a mean 1 year increase of 3 LDH units for 15 nonanemic patients and 242 units in 17 anemic patients. The reticulocyte levels did not demonstrate any progressive increase in the anemic group. The LDH level was the most useful predictor of future anemia. A value of 250 units predicted anemia on the next yearly visit with 28 percent false positive and 4 percent false negative readings. The reticulocyte count of more than 2.5 percent also placed the patient at greater risk of anemia. A serum hemoglobin level in excess of 40 mg 100 ml was common in the anemic patients and was present in only 3 of 17 nonanemic patients. It is suggested that the serum LDH level should be monitored in all patients with the aortic totally cloth-covered prosthesis. Values in excess of 250 units (four times the upper limit of normal by other LDH methods) or increasing levels, or both, suggest future anemia.