Preoperative heparin therapy causes immune-mediated hypotension upon heparin administration for cardiac surgery

J Cardiothorac Vasc Anesth. 2010 Feb;24(1):69-72. doi: 10.1053/j.jvca.2009.10.015.


Objective: To evaluate whether patients with positive or negative heparin antibodies who received heparin preoperatively by continuous infusion developed cardiovascular changes upon heparin administration prior to cardiopulmonary bypass.

Design: Clinical trial.

Setting: Single institution, academic hospital.

Participants: Eighty (80) patients with good ventricular function on low-dose heparin infusion prior to surgery.

Interventions: Patients were divided into 2 equal groups: group A had negative heparin antibodies (% ratio < 0.26), group B had positive heparin antibodies (% ratio > 1.2). All patients received heparin, 400 units/kg, prior to institution of cardiopulmonary bypass. Cardiovascular changes, activated coagulation time (ACT), and histamine levels were measured before and 5 minutes after administration of heparin. Platelets also were counted before and 6 hours after surgery.

Measurements and main results: Significant hypotension and decreased cardiac index occurred in patients with positive heparin antibodies who received heparin prior to cardiac surgery. Histamine levels increased significantly 5 minutes after heparin administration. Significant thrombocytopenia occurred 6 hours after surgery in group B patients. There was a good correlation between heparin antibodies, histamine levels, thrombocytopenia and cardiovascular changes. Group B patients also had heparin resistance as manifested by a lower ACT after the loading doses of heparin.

Conclusion: Patients with positive heparin antibodies pretreated with heparin prior to surgery developed a type of immune-mediated cardiovascular changes and postoperative thrombocytopenia.

MeSH terms

  • Adult
  • Aged
  • Antibodies / blood*
  • Anticoagulants / administration & dosage
  • Anticoagulants / adverse effects*
  • Anticoagulants / immunology
  • Coronary Artery Bypass / methods*
  • Female
  • Hemodynamics / drug effects
  • Heparin / administration & dosage
  • Heparin / adverse effects*
  • Heparin / immunology
  • Histamine / blood
  • Humans
  • Hypotension* / chemically induced
  • Hypotension* / immunology
  • Male
  • Middle Aged
  • Platelet Count
  • Preoperative Care
  • Prospective Studies
  • Thrombocytopenia / chemically induced
  • Thrombocytopenia / immunology
  • Whole Blood Coagulation Time


  • Antibodies
  • Anticoagulants
  • Histamine
  • Heparin