Acute Mesenteric Ischemia

Etiology

Vascular


Etiology

Arterial Embolism

Source of Arterial Embolism

  • Cardiac Source: most arterial emboli originate from a cardiac source
    • Atrial Fibrillation/Flutter (see Atrial Fibrillation, [[Atrial Fibrillation]] and Atrial Flutter, [[Atrial Flutter]])
    • Atrial Myxoma (see Atrial Myxoma, [[Atrial Myxoma]]): usually located in the left atrium
    • Endocarditis (see Endocarditis, [[Endocarditis]])
      • Infectious Endocarditis
      • Non-Infectious (Marantic) Endocarditis: due to systemic lupus erythematosus (SLE), RA, malignancy, sepsis, severe burns
    • Left Atrial/Left Atrial Appendage Thrombus (see Intracardiac Thrombus, [[Intracardiac Thrombus]])
    • Left Ventricular Thrombus (see Intracardiac Thrombus, [[Intracardiac Thrombus]])
      • Myocardial Infarction with Left Ventricular Aneurysm (see Left Ventricular Aneurysm, [[Left Ventricular Aneurysm]]): usually antero-apical with associated decreased systolic function
      • Left Ventricular Dysfunction/Cardiomyopathy with Decreased Cardiac Output (see Congestive Heart Failure, [[Congestive Heart Failure]])
    • Mechanical Prosthetic Mitral/Aortic Valve: usually in the setting of inadequate anticoagulation
    • Mitral Annular Calcification
    • Papillary Fibroelastoma: cardiac tumor usually found on the mitral/aortic valves
  • Arterial Source: account for 20% of arterial emboli
    • Aneurysm
    • Aortic Atherosclerotic Plaque/Cholesterol Emboli Syndrome (see Cholesterol Emboli Syndrome, [[Cholesterol Emboli Syndrome]]): risk of embolization is increased with increased plaque thickness, plaque ulceration or mobility, and cardiovascular procedures (cardiac catheterization/intra-aortic balloon pump/cardiac surgery may dislodge the plaque)
  • Paradoxical Embolism: account for 2-4% of arterial emboli
    • Epidemiology
      • Patients with paradoxical embolization are typically younger (mean age: 39) than patients with other types of arterial thromboembolization (mean age: 68)
      • Patients with paradoxical embolization typically have little evidence of cardiac or peripheral arterial disease
    • Mechanism: venous thrombosis that traverses a right-to-left intracardiac shunt (patent foramen ovale, atrial septal defect, atrial septal aneurysm)
    • Venous Sources
      • Upper/Lower Extremity Deep Venous Thrombosis (DVT)

Destination of Arterial Embolism

  • General Comments
    • Lower extremities are affected more commonly than upper extremities
    • Emboli commonly lodge in sites of arterial narrowing: at atherosclerotic plaques or bifurcation points (common femoral bifurcation, common iliac bifurcation, popliteal artery bifurcation)
  • Femoral Artery: 28% of cases
  • Upper Extremity Artery: 20% of cases
  • Aortoiliac: 18% of cases
  • Popliteal Artery: 17% of cases
  • Visceral Artery: 9% of cases
  • Other Artery: 9% of cases

Arterial Thrombosis

  • General Comments
    • Arterial thrombosis usually occurs at the site of an atherosclerotic plaque, in arterial aneurysms, at the site or within a prior revascularization (stents, grafts), or in a vein bypass (usually at a site of venous abnormality)
  • Aneurysm with Thrombosis
  • Arteritis/Vasculitis (see Vasculitis, [[Vasculitis]])
  • Atherosclerotic Plaque: the degree of limb ischemia in a patient with pre-existing atherosclerotic plaques in the affected distribution may be less severe, due to the prior development of collateral circulation
  • Entrapment Syndrome
  • Ergotism (see Ergotism, [[Ergotism]])
  • Hypercoagulable State: arterial thrombosis may occur in these patients even in normal limb arteries
  • Leukostasis (see Leukostasis, [[Leukostasis]])
  • Low-Flow State
  • Methamphetamine Intoxication (see Methamphetamine, [[Methamphetamine]]): associated with “body packing” and “body stuffing”
  • Vascular Grafts/Stents

Arterial Trauma

  • Blunt Arterial Trauma
  • Penetrating Arterial Trauma
  • Iatrogenic Arterial Trauma
    • Cardiac Catheterization: incidence of arterial complications following cardiac catheterization (hematoma, pseudoaneurysm, arteriovenous fistula, arterial occlusion, cholesterol emboli syndrome) is between 1.5-9%
      • Arterial occlusions can occur due to intimal flaps/dissections or embolization of thrombus from the arterial sheath site

Physiology

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Diagnosis

  • Abdominal/Pelvic CT
    • Pneumatosis Intestinalis
    • Gas in Portal Vein
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Clinical Manifestations

Gastrointestinal Manifestations

Renal Manifestations

Other Manifestations

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Treatment

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References

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