Indexes of intravascular hemolysis, quantification of coagulation factors, and platelet survival in patients with porcine heterograft valves

Evaluation of hemolysis in patients with prosthetic heart valves

The primary mechanism and most common cause of hemolytic disease in patients with prosthetic heart valves are mechanical trauma to red blood cells and paraprosthetic valvular regurgitation, respectively. Presenting features in patients with this condition include anemia, congestive heart failure, fatigue, jaundice, dark urine, and a regurgitant murmur. Various laboratory studies can be utilized to diagnose hemolytic anemia and to assess the severity of hemolysis. Transthoracic echocardiography, transesophageal echocardiography, and Doppler studies including color Doppler are useful imaging methods to assess valve function. Treatment is usually medical (oral iron); however, in patients with paravalvular regurgitation, surgery is often required to correct the anemia.

Contegra Pulmonary Valved Conduits Cause No Relevant Hemolysis

BACKGROUND

Contegra is a bovine jugular vein graft for pediatric RVOT reconstruction. Regular blood draws belong to a (controlled phase I) study protocol aiming at FDA-admission that included the first 60 patients. After 3.3 years we found not a single case of clinically relevant hemolysis and looked for reasons to eliminate this traumatic procedure from the protocol.

METHODS

Age of the patients ranged from 2 days to 17.4 years (median 1.6 years). Out of them 26 were males and 34 were females. Blood samples were taken before implant, before discharge, 1, 3, 6, and then every 6 months after implantation. Haptoglobin, free hemoglobin, reticulocytes, and hemoglobin were determined. We evaluate a total follow-up time of 132.6 years and 365 blood probes. We normalized the values to standard deviations, built a score (1 point for each value pointing toward hemolysis with at least two standard deviations) to compare divergent findings, and compared pre- and postoperative values. Finally, we analyzed the role of three patients with coexisting mechanical valve prostheses.

RESULTS

High free hemoglobin was not associated with lower hemoglobin, indicating no chronic hemolysis. A high RVOT gradient as possible shear stress indicator was not associated with low haptoglobin or higher score values. All parameters turned into or toward normal ranges and showed less hemolysis than preoperatively. A mean of 1.1 parameters indicated (clinically irrelevant) hemolysis after 6 months or later. Haptoglobin was significantly lower in mechanical valve patients.

CONCLUSION

There is no hint that Contegras cause hemolysis.