What are the absolute contraindications to heparin infusion?

Absolute Contraindications to Heparin Infusion

Heparin infusion is absolutely contraindicated in patients with history of heparin-induced thrombocytopenia (HIT), known hypersensitivity to heparin or pork products, uncontrolled active bleeding, and when suitable blood coagulation tests cannot be performed at appropriate intervals. 1

Detailed List of Absolute Contraindications

1. Heparin-Induced Thrombocytopenia (HIT)

• History of HIT or heparin-induced thrombocytopenia with thrombosis (HITT) 1
• Any administration of heparin is strictly contraindicated in patients with confirmed HIT, including heparin locks, catheter flushes, or routine administration 2
• The risk of recurrent HIT with re-exposure can lead to severe thrombotic complications and increased mortality

2. Hypersensitivity Reactions

• Known hypersensitivity to heparin or pork products 1
• History of anaphylactoid reactions to heparin preparations

3. Uncontrolled Active Bleeding

• Active major bleeding at any site, tissue, or organ 1
• Exception: When bleeding is due to disseminated intravascular coagulation (DIC), heparin may still be considered 1

4. Inability to Monitor

• Situations where suitable blood coagulation tests (e.g., whole blood clotting time, partial thromboplastin time) cannot be performed at appropriate intervals 1
• This contraindication applies specifically to full-dose heparin therapy; low-dose heparin generally doesn't require this level of monitoring

High-Risk Scenarios Requiring Caution

While not absolute contraindications, the following conditions require extreme caution when considering heparin infusion:

• Severe thrombocytopenia (platelets <50,000/mcL) 2
• Uncontrolled arterial hypertension (systolic >200 mmHg, diastolic >110 mmHg) 2
• Severe renal impairment 2
• Liver failure with elevated INR (>1.5) 2
• Recent central nervous system bleeding or high-risk intracranial/spinal lesions 2
• Recent spinal anesthesia or lumbar puncture 2
• Recent major surgery with high bleeding risk 2

Alternative Anticoagulation Options

When heparin is contraindicated but anticoagulation is necessary:

1. Direct Thrombin Inhibitors:

   • Bivalirudin - preferred for cardiac surgery when needed 2, 3
   • Argatroban - preferred in renal impairment 2

2. For HIT patients requiring cardiac surgery:

   • Antiplatelet agents (tirofiban, cangrelor) combined with heparin for specific cardiac procedures 2, 3
   • Bivalirudin is the preferred alternative for cardiac surgery with cardiopulmonary bypass 2

3. For renal replacement therapy in HIT:

   • Citrate or argatroban are preferred for circuit anticoagulation 2

4. For mechanical thromboprophylaxis:

   • Intermittent pneumatic compression devices when pharmacological prophylaxis is contraindicated 2

Monitoring Recommendations

• All patients receiving heparin should have baseline platelet count before starting treatment 4
• For patients with previous heparin exposure within 100 days, obtain baseline platelet count and repeat 24 hours after starting heparin 4
• For patients on unfractionated heparin, monitor platelet counts every other day from days 4-14 4
• If platelet count falls by ≥50% or below normal range, or if new thrombosis develops between days 4-14, consider HIT and assess clinically 4

Clinical Pitfalls to Avoid

• Don't delay alternative anticoagulation when HIT is strongly suspected - waiting for laboratory confirmation can lead to thrombotic complications 4
• Avoid warfarin in acute HIT as it can worsen hypercoagulability by depleting protein C 5
• Don't administer prophylactic platelets to patients with HIT as this can worsen thrombotic risk 4
• Remember that HIT can present with delayed onset, even after heparin has been discontinued 5
• Recognize that thrombotic complications in HIT can be severe and include venous and arterial thrombosis, limb ischemia, and skin necrosis 5

When heparin is absolutely contraindicated but anticoagulation is necessary, prompt consultation with hematology is recommended to determine the most appropriate alternative anticoagulant based on the specific clinical scenario.