title: Clinical measures of heparin's effect and thrombin inhibitor levels in pediatric patients with congenital heart disease.
abstract: In this investigation, we examined the relationship among three thrombin inhibitors, antithrombin III (ATIII), heparin cofactor II (HCII), and alpha-2-macroglobulin (alpha2M), and several clinical tests of heparin's effect in pediatric patients with congenital heart disease undergoing cardiopulmonary bypass. One hundred eighteen children were stratified into six age groups: <1 mo, 1-3 mo, 3-6 mo, 6-12 mo, 12-24 mo, and >10 yr. Baseline ATIII, HCII, and alpha2M values were measured. Baseline celite- and kaolin-activated clotting times (ACT) were also measured and repeated 3 min after a standard heparin dose of 400 U/kg. Differences in ACT values before and after heparin administration and a heparin dose-response relationship were calculated for each patient. Kaolin-activated ACT tests showed less variation after heparin administration than celite-activated tests. In contrast to what has been demonstrated in adults, ATIII showed no positive correlation with the clinical tests of heparin's effect nor did the other thrombin inhibitors. Additionally, patients <1 mo old had unexpectedly low levels of alpha2M accompanying their expected low levels of ATIII and HCII. Our findings raise concerns about the ability of heparin to adequately anticoagulate these neonates during cardiopulmonary bypass and, consequently, challenge the accuracy of ACT prolongation to truly reflect the extent of their anticoagulation.
authors.affiliation: Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA. nina_guzzetta@emoryhealthcare.org
authors.forename: Nina A
authors.initials: NA
authors.lastname: Guzzetta
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Miller
authors.forename: Kathy
authors.initials: K
authors.lastname: Todd
authors.forename: Fania
authors.initials: F
authors.lastname: Szlam
authors.forename: Renee H
authors.initials: RH
authors.lastname: Moore
authors.forename: Keith K
authors.initials: KK
authors.lastname: Brosius
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Wilson
authors.forename: Anna M
authors.initials: AM
authors.lastname: Cohen
authors.forename: Steven R
authors.initials: SR
authors.lastname: Tosone
mesh_terms: D000991:Antithrombins / Q000494:pharmacology / Q000627:therapeutic use*; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D006330:Heart Defects, Congenital / Q000097:blood* / Q000188:drug therapy* / Q000453:epidemiology; D006493:Heparin / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010976:Platelet Count; D011446:Prospective Studies; D013917:Thrombin / Q000037:antagonists & inhibitors*
chemical_list: D000991:Antithrombins; D006493:Heparin; D013917:Thrombin