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Principal Developer: A. Roussin Thrombolytic Therapy in Peripheral Arterial Disease Introduction Thrombolysis
for arterial insufficiency dates back five decades but comparative data with surgery date
back one decade only. Systemic fibrinolytic therapy is not effective and has long given
way to intra-arterial thrombolysis. Despite this, the role of thrombolytic therapy is
still controversial and requires considerable clinical expertise with a team approach
usually consisting of an interventional radiologist, a vascular surgeon and/or an
internist. The benefit of pharmacological clot lysis must always be weighted against
surgical intervention and the risk of bleeding associated with fibrinolysis. All actual
intra-arterial lysis protocols result in a certain degree of systemic fibrinolysis,
responsible for a real risk of major bleeding comparable to fibrinolysis for myocardial
infarction. In particular, intracerebral hemorrhage occurs in up to 1% of treated cases.
Although all major vascular centers use fibrinolytic therapy as part of their
armamentarium, there is no regulatory agency approving any protocol in Indications
Surgical embolectomy, with a Fogarty catheter for example, is the preferred
mode of intervention for proximal acute arterial embolic occlusion. Surgery results in
faster restoration of blood flow than fibrinolysis, without the risk of hemorrhage. Local
fibrinolysis is occasionally used per- or post-operatively in this context only if there
is additional distal clot embolisation difficult to reach surgically and only if there is
risk of tissue loss. Acute thrombotic arterial occlusion: native arteries Although fibrinolysis sometimes results in less extensive surgical interventions (STILE and TOPAS studies, both randomized), major end points such as mortality and amputation-free survival are not significantly different. Nevertheless, timing being the priority, fibrinolysis can precede surgery and vice-versa depending on the immediate availability of these interventions. It is crucial to remember that 8 hours is the time limit to revascularize a profoundly ischemic limb without incurring tissue damage or gangrene. Since intra-arterial fibrinolysis cannot be reliably counted upon to restore adequate flow in 8 hours when there is an underlying atherosclerotic lesion, serious consideration should always be given to surgical revascularisation. Acute thrombotic arterial occlusion: occluded bypass It is in this field that intra-arterial fibrinolysis is perhaps the most useful, permitting better planning of the subsequent surgery and resulting in a less extensive procedure. But then again, long term major end points are not necessarily better. It is important to remember that thrombosis of femoro-popliteal or similar bypasses are related to early or late surgical stenosis and atherosclerosis and that restoring flow is usually not sufficient to insure continued patency. Sub-acute (no immediate muscular or neurologic threat) and chronic peripheral atherosclerotic occlusion Intra-arterial fibrinolysis can be considered for recently ischemic limbs, ideally if ischemia has been present for less than 14 days. Surgery has been demonstrated superior than thrombolysis for limbs with more than 14 days of sub-acute ischemia. Occluded dialysis access grafts Local
fibrinolysis is a useful adjunctive technique during surgery when there are residual
thrombi or new thrombi arising from a complicated procedure. The risk of bleeding must be
weighted against the importance of tissue ischemia or graft compromise by poor occluded
run-off.
Agents and mode of administration Dosage and methods of administration have been described in a "Standards of Practice" document published in 2005 by the Society of Interventional Radiology for the percutaneous management of acute limb ischemia. A previous 2003 consensus document by the Society of Vascular & Interventional Radiology. See references 1 and 12
Urokinase (Abbokinase™) has been the agent of choice in the last decade, because of
possibly better results than with Streptokinase, although no head to head double blinded
prospective comparative study has ever been published. However, Urokinase is presently not
available in References 10. Kessel D, Berridge D, Roberston I. Infusion techniques for peripheral arterial thrombolysis. Cochrane Database Syst Rev 2004; 1: CD000985 11. Ouriel K. Thrombolytic Therapy for Acute Peripheral Arterial Occlusion. Chapter 16 p 213-223 in Comprehensive Vascular and Endovascular Surgery. Ed Mosby 2004 12. Rajan DJ et al. Quality Improvement Guidelines for Percutaneous Management of Acute Limb Ischemia. J Vasc Interv Radiol 2005; 16: 585-595 13. Hull JF et al. Tenecteplase in Acute Lower-leg Ischemia: Efficacy, Dose, and Adeverse Events. J Vasc Interv Radiol 2006; 17: 629-636 |