Resident Teaching Conference 3/12/ PDF Free Download

Resident Teaching Conference 3/12/2010

Goals Definition and Classification of Acute Limb Ischemia Clinical Assessment of the Vascular Patient History and Physical Diagnostic Modalities Management of Acute Limb Ischemia Anticoagulation Thrombolysis Surgical Atheroembolic Disease Briefly discuss Infrainguinal Procedures Indications and Outcomes

Introduction Acute Limb Ischemia: Sudden reduction in limb perfusion that threatens viability Incidence 1.7/10,000 per year Variable clinical presentation Outcomes: Average mortality ~ 15% Amputation rates ~ 10-30% Goals of management Limb Salvage Minimize morbidity Prevention of death

Incidence of Co- morbidities

Clinical History Key Information Dominant symptoms (pain, loss of function, etc.) Onset and Duration (embolic vs. thrombotic) Sudden/Chronic Claudication Prior Operations Prior or Current Cardiac Disease Risk Factors for Atherosclerosis (HTN, DM, HL, Tobacco)

Physical Exam Pain Location, Severity Pallor/Poikilothermia Poikilothermia Pale discoloration, coolness Seen in early stages Typically 1 level below point of occlusion Pulselessness helps to localize lesion Paresthesias Earliest sign of tissue loss Light touch, 2-point, 2 proprioception Paralysis late finding>>advanced ischemia Motor Exam important

PULSE EXAM

Staging Acute Limb Ischemia Is the Limb viable?

Diagnostic Modalities EKG, Lab Panel, Plain Films Diagnostic imaging is dependent on clinical severity Doppler Segmental Pressures/ABI Assesses arterial and venous signals Normal ABI: 0.9 to 1.2 Claudication: 0.4 to 0.9 Limb-threatening ischemia: 0.0 to 0.4 Segmental Pressure drop > 15mm Hg significant

Diagnostic Duplex Ultrasonography Modalities Measures velocities ability to locate lesions Assesses plaque morphology, stenoses, thrombi

Triphasic Biphasic Monophasic Dampened

Diagnostic Modalities Arteriography Gold Standard for diagnosis of Acute Limb Ischemia For pts with viable limbs who can tolerate delay Aides in planning revascularization Assists in differentiating embolic vs. thrombotic process

Diagnostic Modalities CTA/MRA Noninvasive Excellent Reconstructed images Quick Contrast

Etiology of Acute Limb Ischemia Thrombosis vs. Embolism

Etiology of Acute Limb Ischemia Thrombosis Always develops from underlying lesion Longstanding disease Embolism Heart most common source Common Causes Atrial Fibrillation MI Prosthetic Valve Tumors/myxomas Endocarditis Non-Cardiac Aneurysms and Unstable plaques

Most Common Sites Of Arterial Embolic Occlusions

Management of Acute Limb Ischemia Reduce Morbidity and Mortality Rapid restoration of perfusion Anticoagulation Usually Heparin Begin ASAP Decreases M/M and Increases Limb Salvage Impedes propagation of clot; Not fibrinolytic Action of Heparin Risk of Heparin-induced induced Thrombocytopenia White-clot syndrome

Management of Acute Limb Ischemia Thrombolytic Therapy (Intra-Arterial) ~ 10% patients experience significant bleeding complication Common Drugs: Urokinase, Recombinant t-pat

Thrombolytics vs. Surgical Treatment Rochester Trial Compared Urokinase with Surgery in pts with ischemia <7d At 1 year, mortality was 25% in thrombolysis group and 48% in surgical group Amputation Rates were similar STILE Trial Compared Surgery, Urokinase, and Recombinant t-pat Pts with ischemia <14d had lower amputation rate with thrombolysis; >14d had lower amputation with Surgery TOPAS Trial Compared Surgery with Recombinant Urokinase Pts with ischemia <14d At 1 year, amputation rates similar Thrombolytic group had bleeding complications

Thrombolytics vs. Surgical Treatment Current Recommendations Thrombolytics are effective as initial therapy in pts with Category I or IIa Acute Limb Ischemia secondary to arterial or graft occlusions. Key points to Remember Serial lab monitoring (CBC, coags,, fibrinogen) Heparin drip required post-thrombolysis thrombolysis Lengthy period of treatment Definitive treatment must follow thrombolysis Weigh benefits of thrombolytics against surgical intervention Consider risk of bleeding

Question Which of the following statements about antithrombotic treatments is TRUE? A) ) In the absence of AT3, unfractionated heparin has no significant anticoagulant effect. B) ) Low molecular weight heparins share the ability to accelerate the activity of factor Xa C) ) Warfarin inhibits the absorption of vitamin K from the intestinal tract D) ) Hirudin, a synthetic thrombin inhibitor, is dependent on AT3 for anticoagulant activity E) ) The addition of aspirin to heparin increases the anticoagulant effect without increasing the risk of hemorrhage side effects.

Surgical Treatment Percutaneous Aspiration Thrombectomy Utilizes catheter and syringe to remove embolus/thrombus Useful with fresh clots Often used as adjunct to thrombolysis therapy Percutaneous Mechanical Thrombectomy Utilizes catheter to introduce pressurized stream of saline into thrombus Results in maceration of thrombus Useful with fresh clots

Surgical Treatment Surgical Embolectomy Indicated with profound ischemia >>sensory/motor deficits Lower Extremity: Obtain access to femoral vessels Additional access at popliteal vessels for distal emboli Upper Extremity: Obtain control of brachial, radial and ulnar vessels Completion angiogram Assess for compartment syndrome Heparin>>Warfarin for 6 months Identify responsible lesion for emboli

Compartment Syndrome

Compartment Syndrome History Significant Pain Nerve Impairment Motor Dysfunction Mechanism and Duration of Injury Anticoagulation Physical Severe pain at rest Tense or hard limb Pain with passive stretching (earliest sign) Sensory nerves affected before motor nerves Anterior Compartment >> 1 st web space Pressures > 30mm Hg

Infra-inguinal Procedures Fem-popliteal Bypass Utilized when SFA or Popliteal are occluded Appropriate Origin and Target Imaging must demonstrate patent vessels Ideally popliteal has luminal continuity with 3 terminal branches Above or Below Knee General Sequence: Harvesting of GSV Exposure of all vessels Tunnel creation Distal Anastomosis >> Proximal Anastomosis

Infra-inguinal Procedures Fem-popliteal Bypass Outcome: 4-Year primary patency rates 68% to 80% Limb salvage rates 75% to 80% Similar results with PTFE (above-knee only)

Infra-inguinal Procedures Infra-popliteal Bypass Performed when Fem-pop contraindicated Popliteal segment <7cm Extensive gangrene or foot infection Target s s include 3 distal vessels Must have luminal continuity to foot Stenosis of 50% or less is acceptable at or distal to anastomosis

Infrainguinal Procedures Infrapopliteal Bypass Outcome: 5-Year primary patency rates 60% to 67% Limb salvage rates 70% to 75%

Infrainguinal Procedures Plantar Bypass Target vessels below the ankle Offers alternative to amputation Outcome for DP 3-Year patency rates 58% to 60% Limb salvage rates 75% to 95% Outcome for Plantar or Tarsal vessels 2-Year patency rates 65% to 75% Limb salvage 80%

Question A 77 y/o female presents with a cold left hand. After operative embolectomy, the next step in this patients evaluation should be: A) MRA of the subclavian arteries B) Duplex examination of the carotid arteries C) Echocardiogram D) Cardiac catheterization E) Adson s s maneuver

Question A 77 y/o female presents with a cold left hand. After operative embolectomy, the next step in this patients evaluation should be: A) MRA of the subclavian arteries B) Duplex examination of the carotid arteries C) ) Echocardiogram D) Cardiac catheterization E) Adson s s maneuver

Atheroembolism Source Unstable plaque at inflection points Aneurysmal sacs of Aorta and Peripheral vessels Clinical Presentation Focal toe ischemia (blue-toe syndrome) Palpable distal pulses

Algorithm for Management of Atheroemboli Atheroembolism

Question Which of the following statements about the natural history of intermittent claudication is TRUE? A) Five-year survival is >90% B) Most patients eventually require revascularization to avoid amputation C) 1 in 4 patients will eventually undergo major amputation D) Intermittent claudication is a risk factor for adverse cardiovascular events. E) Abstinence from tobacco does not improve symptoms

Question Which of the following statements about the natural history of intermittent claudication is TRUE? A) Five-year survival is >90% B) Most patients eventually require revascularization to avoid amputation C) 1 in 4 patients will eventually undergo major amputation D) ) Intermittent claudication is a risk factor for adverse cardiovascular events. E) Abstinence from tobacco does not improve symptoms