vascular module lecture 2: ACUTE LIMB ISCHEMIA LECTURE 2024.pptx

Acute limb ischemia (ALI) occurs when there is sudden decrease in limb perfusion that threatens limb viability and requires urgent diagnosis and management to prevent loss of life and limb.
If ALI is suspected based on history and physical examination, intravenous (IV) heparin should be initiated immediately and vascular surgery consulted. The thrombolytic agent - 24 hours to 48 hours.
Profound ischemia who may not tolerate such a prolonged procedure are not candidates for catheter-directed thrombolysis.
Major bleeding occurs in 6% to 9% of patients, including intracranial hemorrhage in less than 3%
Factors associated with an increased risk of bleeding include the intensity and duration of thrombolytic therapy, the presence of hypertension, patient age greater than 80 years, and thrombocytopenia

1. KEY POINTS Acute limb ischemia (ALI) occurs when there is sudden decrease in limb perfusion that threatens limb viability and requires urgent diagnosis and management to prevent loss of life and limb. If ALI is suspected based on history and physical examination, intravenous (IV) heparin should be initiated immediately and vascular surgery consulted.

2. KEY POINTS Acute limb ischemia (ALI) occurs when there is sudden decrease in limb perfusion that threatens limb viability and requires urgent diagnosis and management to prevent loss of life and limb. If ALI is suspected based on history and physical examination, intravenous (IV) heparin should be initiated immediately and vascular surgery consulted.

3. KEY POINTS Assessment of 6 P’s (pulses ) - by palpation and Doppler flow, sensation, and motor strength determines limb viability. Patients are then classified based on viability of the ischemic limb as follows: viable (stage I), marginally threatened ( IIa ), immediately threatened (IIb), and irreversibly damaged (III).

4. KEY POINTS Assessment of pulses (by palpation and Doppler flow), sensation, and motor strength determines limb viability. Patients Classified based on viability of the ischemic limb as follows: viable (stage I ), marginally threatened ( IIa ) , immediately threatened (IIb ), and irreversibly damaged (III).

5. KEY POINTS Endovascular thrombolysis is most appropriate for patients with a viable or marginally threatened limb (I and IIa ), acute occlusion (less than 2 weeks duration), and a history strongly suggestive of arterial or graft thrombosis. Surgical revascularization is preferred for patients with an immediately threatened limb (IIb), occlusion of more than 2 weeks’ duration, proximal occlusion ( suprainguinal ), and embolic occlusion.

6. KEY POINTS Endovascular thrombolysis is most appropriate for patients with a viable or marginally threatened limb (I and IIa ), acute occlusion (less than 2 weeks duration), and a history strongly suggestive of arterial or graft thrombosis. Surgical revascularization is preferred for patients with an immediately threatened limb (IIb), occlusion of more than 2 weeks’ duration, proximal occlusion ( suprainguinal ), and embolic occlusion .

7. Initial Management – Goal Limb/life Preservation of limb and life, Restoration of blood flow, Prevention of recurrent thrombosis or embolism. Receive an IV heparin bolus + continuous heparin infusion. Current practice is to administer IV unfractionated heparin with 80 U/kg to 150 U/kg bolus followed by infusion of 18 U/kg/h Achieve therapeutic heparin level and activated partial thromboplastin time at 2 to 2.5 times baseline. If HIT or an antithrombin III deficiency, alternative agents, such as direct thrombin inhibitors ( lepirudin or argatroban ), can be used. The decision to administer heparin should not be delayed while waiting for vascular surgery consultation or diagnostic imaging.

8. Aspirin should also be administered. Dependent position to increase perfusion pressure to the limb, and the limb should be kept warm. Adequate pain control is paramount, Resuscitation with IV crystalloid fluids in the hypovolemic patient is advised. Hypoxic patients should receive supplemental oxygen . Acute heart failure and dysrhythmias should be treated promptly to improve limb perfusion.

9. Assessment of limb viability must be performed Vascular surgery consultation obtained to develop a plan for immediate revascularization. Options - Endovascular and surgical therapies.

10. Endovascular therapy Use of thrombolytics, mechanical devices, or both, to restore blood flow to the ischemic limb . During endovascular therapy, a guide wire is used to bypass the occlusion with a catheter, which allows for direct delivery of a thrombolytic agent into the thrombus. Thrombolytic agents ( eg , alteplase, reteplase , and tenecteplase ) convert plasminogen to plasmin Degrades the fibrin clot. systemically (intravenous) or locally via catheter-directed therapy.

11. Endovascular therapy Use of thrombolytics, mechanical devices, or both, to restore blood flow to the ischemic limb. A guide wire to bypass the occlusion with a catheter, direct delivery of a thrombolytic agent into the thrombus. Thrombolytic agents ( eg , alteplase, reteplase , and tenecteplase ) convert plasminogen to plasmin Degrades the fibrin clot. systemically (intravenous) or locally via catheter-directed therapy .

12. Endovascular therapy Use of thrombolytics, mechanical devices, or both, to restore blood flow to the ischemic limb. A guide wire to bypass the occlusion with a catheter, direct delivery of a thrombolytic agent into the thrombus. Thrombolytic agents ( eg , alteplase, reteplase , and tenecteplase ) convert plasminogen to plasmin Degrades the fibrin clot. systemically (intravenous) or locally via catheter-directed therapy.

13. Endovascular therapy Use of thrombolytics, mechanical devices, or both, to restore blood flow to the ischemic limb. A guide wire to bypass the occlusion with a catheter, direct delivery of a thrombolytic agent into the thrombus. Thrombolytic agents ( eg , alteplase, reteplase , and tenecteplase ) convert plasminogen to plasmin Degrades the fibrin clot. Systemically (intravenous) or locally via catheter-directed therapy.

14. The thrombolytic agent - 24 hours to 48 hours . Profound ischemia who may not tolerate such a prolonged procedure are not candidates for catheter-directed thrombolysis. Major bleeding occurs in 6% to 9% of patients , including intracranial hemorrhage in less than 3% Factors associated with an increased risk of bleeding include the intensity and duration of thrombolytic therapy, the presence of hypertension, patient age greater than 80 years, and thrombocytopenia

15. Endovascular thrombolysis is most appropriate for patients with a history strongly suggestive of arterial or graft thrombosis. Patients with a nonviable limb (stage III), bypass graft with suspected infection , or contraindication to thrombolysis (history of intracranial hemorrhage, recent major surgery, or intracranial neoplasm or active bleeding) are not candidates for catheter-directed thrombolysis. Endovascular treatment with thrombolysis is also contraindicated infective endocarditis, tumor emboli, and mural or floating thrombi in the LV or left atrium.

16. Surgical approaches

17. Complications

18. REPERFUSION INJURY

19. REPERFUSION INJURY Hyperkalemia can cause life-threatening cardiac dysrhythmia and cardiac arrest.

20. REPERFUSION INJURY- Myoglobinemia and Rhabdomyolysis Elevated serum muscle enzymes (creatine kinase), Red to brown urine due to myoglobinuria, and Acute renal failure. Saline hydration Urine output of 3 mL/kg/h