Why can't the patient have heparin (unfractionated heparin)?

Absolute Contraindications to Heparin

Heparin is absolutely contraindicated in patients with a history of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia with thrombosis (HITT), active uncontrolled bleeding (except in disseminated intravascular coagulation), known hypersensitivity to heparin or pork products, and in situations where appropriate coagulation monitoring cannot be performed. 1

Primary Contraindications

Heparin-Induced Thrombocytopenia (HIT/HITT)

• Any history of HIT or HITT is an absolute contraindication to heparin use 1
• HIT is a serious antibody-mediated reaction where antibodies develop against platelet Factor 4-heparin complexes, causing in vivo platelet aggregation 1
• HITT represents progression to venous and arterial thromboses, which may be the initial presentation 1
• Even in acute HIT (less than 1 month), heparin should be strictly avoided pre- and postoperatively 2
• For patients with subacute HIT (less than 3 months) requiring cardiac surgery with cardiopulmonary bypass, re-exposure to heparin is contraindicated unless anti-PF4/heparin antibodies are undetectable by ELISA 2

Active Bleeding

• Uncontrolled active bleeding is an absolute contraindication, except when due to disseminated intravascular coagulation 1
• Fatal hemorrhages have occurred with heparin use 1
• Adrenal hemorrhage with acute adrenal insufficiency, ovarian hemorrhage, and retroperitoneal hemorrhage have been reported 1

Hypersensitivity

• Known hypersensitivity to heparin or pork products (including anaphylactoid reactions) is an absolute contraindication 1

Inability to Monitor

• Heparin is contraindicated when suitable blood coagulation tests (whole blood clotting time, partial thromboplastin time) cannot be performed at appropriate intervals 1
• This applies specifically to full-dose heparin; low-dose prophylactic heparin typically does not require monitoring 1

Relative Contraindications and High-Risk Situations

Sepsis-Related Coagulopathy

• In septic patients with active hemorrhage or significant clotting abnormalities, mechanical leg compression devices are preferred over heparin 2
• Thrombocytopenia is frequently present in septic patients, making heparin use problematic 2
• Sepsis creates consumptive coagulopathy and liver dysfunction predisposing to both clotting and bleeding 2

Increased Hemorrhage Risk Conditions

Use heparin with extreme caution (or avoid) in: 1

• Cardiovascular: Subacute bacterial endocarditis, severe hypertension
• Surgical: During and immediately following spinal tap, spinal anesthesia, or major surgery involving brain, spinal cord, or eye
• Hematologic: Hemophilia, thrombocytopenia, vascular purpuras
• Gastrointestinal: Ulcerative lesions, continuous tube drainage of stomach or small intestine
• Other: Active menstruation, liver disease with impaired hemostasis

Special Patient Populations

• Women over 60 years of age have a higher incidence of bleeding with heparin 1
• Patients with hereditary antithrombin III deficiency receiving concurrent antithrombin III therapy require dose reduction due to enhanced anticoagulant effect 1

Alternative Anticoagulants When Heparin is Contraindicated

For Acute HIT

• Argatroban: Direct thrombin inhibitor, preferred in renal impairment 2
• Bivalirudin: Direct thrombin inhibitor with short half-life (20-30 minutes), suggested for PCI in subacute HIT 2
• Danaparoid: Heparinoid with mainly anti-Xa activity, suitable for thrombosis prophylaxis 2
• Fondaparinux: Synthetic pentasaccharide, reasonable for patients with increased bleeding risk 2

For Septic Patients with Contraindications

• Intermittent pneumatic compression devices are recommended when heparin is contraindicated (thrombocytopenia, severe coagulopathy, active bleeding, recent intracerebral hemorrhage) 2

Critical Clinical Pitfalls

Medication Errors

• Never use Heparin Sodium Injection as a "catheter lock flush" product 1
• Fatal hemorrhages have occurred in pediatric patients when 1 mL vials containing 10,000 units were confused with catheter lock flush vials 1
• Carefully examine all vials to confirm correct strength before administration 1

Monitoring Requirements

• Any unexplained fall in hematocrit, blood pressure, or other unexplained symptoms should prompt serious consideration of hemorrhagic event 1
• For patients with 4Ts score ≥4 (intermediate/high HIT probability), proceed immediately to ELISA testing and discontinue heparin without awaiting results 3
• If 4Ts score ≤3 (low probability), HIT is extremely unlikely and heparin may be resumed 3