Heart
Ischemic heart disease
Coronary arteritis and aneurysms


Topic Completed: 1 March 2015

Revised: 25 February 2019

Copyright: 2015-2019, PathologyOutlines.com, Inc.

PubMed Search: Coronary arteritis and aneurysms [title]
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Cite this page: Amita R Coronary arteritis and aneurysms. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/heartcoronaryarteritis.html. Accessed March 23rd, 2019.
Definition / general
  • Coronary artery aneurysm (CAA): localized, irreversible dilatation of blood vessel lumen that exceeds the diameter of the adjacent normal segment by more than 1.5 fold
  • Ectasia: diffuse dilatation of coronary arteries that involves 50% or more of the length of the artery
  • The first description of a CAA was by Morgagni in 1761 (Am Heart J 1985;109:129)
Epidemiology
  • Studies from Germany and US found a 1.4% incidence of coronary artery aneurysms
Sites
  • Coronary ostial, epicardial and intramural segments
  • Right coronary artery is most commonly affected (40.4%); also left anterior descending artery (32.3%), left circumflex artery (23.4%), left main coronary artery (3.5%)
Pathophysiology
  • Increased proteolysis of extracellular matrix proteins is probably the mechanism of coronary artery aneurysm formation
  • Matrix metalloproteinase 1 (interstitial collagenase), matrix metalloproteinase 2 (gelatinase A), matrix metalloproteinase 3 (stromelysin 1), matrix metalloproteinase 9 (gelatinase B), and matrix metalloproteinase 12 (macrophage metalloelastase) are capable of degrading essentially all components of arterial wall matrix (elastin, collagen, proteoglycans, laminin, fibronectin, etc.), and are present in elevated concentrations in aortic aneurysms, while there are decreased levels of tissue inhibitors of matrix metalloproteinases
Etiology
  • Atherosclerosis (50% of cases)
  • Coronary vasculitis:
    • Infectious: acute bacterial, fungal or viral; chronic syphilitic aortitis or tuberculosis
    • Noninfectious:
      • Coronary ostia and epicardial arteries
      • Takayasu arteritis
      • Rheumatoid arthritis
      • Ankylosing spondylitis
    • Epicardial and intramural arteries
      • Giant cell arteritis
      • Polyarteritis nodosa
      • Kawasaki disease
      • Acute rheumatic fever
      • Collagen vascular diseases: granulomatosis with polyangiitis (Wegener's) and Churg-Strauss syndrome
      • Buerger disease
      • Atherosclerosis induced periarteritis
      • Drugs
    • Predominantly intramural arteries
      • Sarcoidosis
  • Others
    • Trauma
    • Dissection
    • Angioplasty
    • Drug eluting stents
    • Congenital malformation: Marfans syndrome
    • Cocaine use
Clinical features
  • Commonly presents with angina pectoris, dyspnea, edema or sudden death
Diagnosis
  • Coronary angiography, intravascular ultrasound and, on most occasions, autopsy
Radiology description
  • Coronary angiography, intravascular ultrasound
Prognostic factors
  • Prognosis of patients with coronary artery atherosclerosis is similar with and without coronary aneurysms
Case reports
Treatment
  • TGF beta inhibitors: angiotensin II type 1 receptor antagonists such as losartan which prevent aortic aneurysms in a mouse model of Marfan syndrome
  • The secretion of metalloproteinases 1, 2, 3, and 9 from macrophages and vascular smooth muscle cells can be inhibited by statins (hydroxymethylglutaryl coenzyme A reductase inhibitors), including simvastatin, lovastatin and cerivastatin
  • Antiplatelet therapy (with aspirin or clopidogrel) or anticoagulation (with warfarin) to prevent thrombosis
  • Stenting and coil embolization
  • Surgical repair becomes mandatory when a coronary aneurysm is 3 times larger than the original vessel diameter
Clinical images

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50 mm round mass with calcification

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Descending artery aneurysm

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Coronary angiogram

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After CABG

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Distal left main aneurysm

Gross description
  • An aneurysm is commonly defined as a localized dilatation exceeding the diameter of adjacent normal segments by 50%
  • Giant coronary aneurysms are usually more than 2 cm but the Committee of the American Heart Association defines giant aneurysms as greater than 8 mm
  • A true arterial aneurysm can be fusiform or saccular; fusiform aneurysms are much more common
  • A false aneurysm or pseudoaneurysm is a rupture of the artery contained by the tunica adventitia or a blood clot
Gross images

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Right coronary artery

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Circumflex coronary artery aneurysm

Microscopic (histologic) description
  • All coronary aneurysms have destruction of the tunica media which is thinned or no longer identifiable between the tunica intima and tunica adventitia
  • The normal tunica media is replaced by hyalinized connective tissue
  • Destruction of the internal elastic lamina sometimes obscures the border between diseased tunica media and tunica intima
  • In atherosclerosis, lipid deposits, foam cells, cholesterol clefts, eosinophilic debris, calcifications, neovascularization, an inflammatory reaction and hemorrhage can be seen, sometimes limited to the tunica intima or extending into the tunica media
  • The inflammatory reaction consists primarily of lymphocytes and macrophages, sometimes with foreign body giant cell formation around cholesterol clefts; neutrophils, eosinophils, and plasma cells may be present
  • Thrombus formation is invariably present on the luminal surface of coronary aneurysms
  • Eosinophilic coronary periarteritis is characterized by:
    • Eosinophilic inflammatory infiltration limited to the adventitia; periadventitial soft tissue is recognized in the epicardial large coronary arteries
    • All 3 main coronary artery branches are affected, with the left anterior descending artery most frequently affected
    • Medial smooth muscle cells of the affected coronary artery and both internal and elastic laminae are well preserved
    • Fibrinoid necrosis or granuloma as seen in polyarteritis nodosa or allergic granulomatous angina are not found in or around the inflammatory area
    • No findings of any type of vasculitis in any other tissues or organs
Microscopic (histologic) images

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Dense inflammatory infiltration

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Condensing fibrin and a few fibroblasts

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Elastica-van Gieson

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Verhoeff van Gieson

Electron microscopy images

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Eosinophil infiltrating adventitia

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