Abstract 11596: Should we Focus on Hematocrit or Hemoglobin in Patients with Eisenmenger Syndrome?
Objectives: To evaluate whether whole blood viscosity (WBV) for a certain hemoglobin (Hb) or hematocrit (Hct) differs between iron-deficient and iron-replete patients with Eisenmenger syndrome (ES).
Background: Iron deficiency has been identified as a predictor of adverse outcome in patients with ES. Although an increase in Hb is important to maintain arterial oxygen content, the concomitant increase in Hct will increase WBV. We hypothesize that iron-deficient patients not only have a lower Hb but also a higher WBV for a certain Hb.
Methods: Seventy-four patients with ES were included in the study. Hct, Hb, mean corpuscular hemoglobin (MCH) and iron status were obtained. WBV was estimated using the formula proposed by Hutton et al: Ln WBV = (Hb concentration (g/dL) / ln MCH (pg)) x (0.57 - 0.0542 ln shear rate) + 0.3214
Results: There was a linear relationship between Hct and WBV in iron-replete (R²=0.834; P<0.0001) and iron-deficient (R²=0.866; P<0.0001) patients (interaction; P=0.808). There was a linear relationship between Hb and WBV in iron-replete (R²=0.923; P<0.0001) and iron-deficient patients (R²=0.854; P<0.0001) (interaction; P<0.0001). There was a relationship between oxygen carrying capacity and WBV in iron-replete (R²=0.507; P<0.0001) and iron-deplete patients (R²=0.349; P=0.001). (interaction; P=0.037).
Conclusions: As Hb is the main determinant of oxygen carrying capacity and Hct the main determinant of viscosity, we were able to show that iron-deficient patients have a higher viscosity for a certain hemoglobin because of a higher hematocrit. Both parameters are not interchangeable and iron-deficient patients not only have a suboptimal oxygen carrying capacity but also a higher viscosity for the same oxygen carrying capacity.
- © 2011 by American Heart Association, Inc.