The haematocrit--an important factor causing impaired haemostasis in patients with cyanotic congenital heart disease

Background: Patients with cyanotic congenital heart disease(CCHD) have haemostatic abnormalities, which result in an increased risk of bleeding. The cause is unknown, but recent studies have indicated that an elevated haematocrit, which is present in cyanotic patients, could be an important factor. The aim of this study was to characterize the haemostatic profile, examine how changes in haematocrit affect the haemostatic profile, and whether a haematocrit reduction could terminate bleeding in CCHD patients.

Methods: This was a prospective, multicenter study. The haemostatic profile consisting of haematocrit, platelet count and thrombelastography(TEG) was characterized in ninety-eight CCHD patients. To evaluate the influence of haematocrit on the haemostatic profile, 21 of the patients underwent phlebotomy and 16 patients received treatment with an iron supplement. Furthermore ten patients with haemoptysis underwent phlebotomy. The haemostatic profile was reevaluated after interventions.

Results: TEG revealed that patients with CCHD and elevated haematocrit were hypocoagulable due to reduced clot formation and strength. Furthermore a positive correlation between elevated haematocrit and hypocoagulability was present. Interventions such as phlebotomy and treatment with supplemental iron causing significant haematocrit changes confirmed the correlation between haematocrit and the haemostatic profile. Finally a haematocrit reduction by phlebotomy successfully terminated haemoptysis in ten CCHD patients.

Conclusion: Patients with CCHD and elevated haematocrit are hypocoagulable. The hypocoagulable haemostatic profile is positively correlated to increasing haematocrit. An intervention, which increases or decreases haematocrit, changes the haemostatic profile. A haematocrit reduction seems to improve the haemostatic profile, and may thereby terminate bleeding. However, these results warrant further studies.