What is the recommended heparin dosage for a dissection flap?

Heparin Dosage for Arterial Dissection Flap

For patients with arterial dissection flaps, an initial intravenous bolus of 100 units/kg heparin followed by continuous infusion with supplemental doses to maintain ACT between 300-350 seconds is recommended. 1

Initial Anticoagulation Protocol

1. Pre-procedure preparation:

   • Administer aspirin in conjunction with ticlopidine or clopidogrel for 3 days before any planned intervention 1
   • This allows ticlopidine to achieve full functional activity

2. Initial heparin dosing:

   • IV bolus: 100 units/kg 1
   • Continuous infusion: Titrate to maintain target ACT

3. Monitoring and adjustment:

   • Monitor ACT hourly 1
   • Target ACT: 300-350 seconds 1
   • Administer supplemental heparin as needed to maintain target ACT

Post-Procedure Management

For patients with visible arterial dissection flaps:

• Post-procedure heparin:

  • Continue heparin for 24 hours post-procedure 1
  • Target APTT: 1.5-2.3 times control values 1

• Alternative options:

  • Subcutaneous enoxaparin 1 mg/kg twice daily can be used as an alternative 1

Special Considerations

High-Risk Patients

For high-risk patients with arterial dissections, mural thrombosis, or ischemic symptoms:

• Consider abciximab:
  • Initial loading dose: 0.25 mg/kg IV 10-60 minutes before procedure 1
  • Followed by 12-hour IV infusion at 10 μg/min 1
  • When using abciximab, reduce heparin dose to 70 units/kg to maintain ACT around 200 seconds 1
  • Can extend abciximab use up to 24 hours for high-risk cases 1

Type A Aortic Dissection

Recent research suggests that a lower-dose heparin protocol may result in less postoperative bleeding and reduced blood product transfusion requirements in Type A aortic dissection surgeries 2. However, this should be considered in the context of the surgical approach rather than medical management.

Monitoring for Complications

• Thrombotic complications:

  • Intramural thrombosis can occur in >90% of deeply injured arteries even with ACT elevated to 4-5 times control 1
  • Animal studies suggest heparin doses >180 units/kg/h may be required to inhibit thrombosis during angioplasty 1

• Bleeding complications:

  • Monitor for bleeding at sheath insertion sites
  • Regular platelet count monitoring for heparin-induced thrombocytopenia 3

Transitioning to Oral Anticoagulation

After initial management:

• Discontinue heparin after the procedure if no complications 1
• Continue aspirin (325 mg daily) and ticlopidine (250 mg twice daily) or clopidogrel (75 mg daily) for at least 4 weeks 1

Caution

• Standard heparin dosing may not suppress increased thrombin generation in acute coronary syndromes despite adequately prolonged APTT 4
• Higher heparin doses may be required in hypercoagulable states 3
• Routine post-procedural heparin infusion is not recommended due to increased bleeding risk without definite benefits 1