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Aneurysms

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Aneurysms

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Aneurysms

  1. 1. ANEURYSMS
  2. 2. Learning Objectives • Definition • Classification • Pathology • Complication
  3. 3. Definition • Localized abnormal dilation of blood vessel or heart due to blood vessel wall stress. • Weak spot on a blood vessel wall that causes an outward bulging, likened to a bubble or balloon • Congenital or acquired. • Nidus for thrombosis and embolization. • Increase in size Risk of rupture Uncontrolled bleeding • Arises in the heart following a myocardial infarction.
  4. 4. Definition
  5. 5. Classification A. Depending upon composition of the wall
  6. 6. Classification A. Depending upon composition of the wall Trauma to vessel wall
  7. 7. Classification
  8. 8. Classification 1. Saccular having large spherical outpouching. 2. Fusiform having slow spindle-shaped dilatation. 3. Cylindrical with a continuous parallel dilatation. 4. Serpentine or varicose which has tortuous dilatation of the vessel. 5. Racemose or circoid having mass of intercommunicating small arteries and veins. B. Depending upon shape :
  9. 9. Classification
  10. 10. Classification Lateral left carotid arteriogram shows an irregular channel of the giant serpentine aneurysm Cirsoid aneurysm in the right occipital and post-auricular regions in a 19 year old male patient
  11. 11. Classification C. Depending upon location A. Arterial and venous, with arterial being more common. B. Capillaries, specifically capillary aneurysms. C. The heart, including coronary artery aneurysms, ventricular aneurysms, aneurysm of sinus of Valsalva, and aneurysms following cardiac surgery. D. The aorta, namely aortic aneurysms including thoracic aortic aneurysms and abdominal aortic aneurysms. E. The brain, including cerebral aneurysms, berry aneurysms, and Charcot–Bouchard aneurysms. F. The legs, including the popliteal arteries.[citation needed] G. The kidney, including renal artery aneurysm and intraparechymal aneurysms.
  12. 12. Classification D. Depending upon pathogenetic mechanisms : 1. Atherosclerotic (arteriosclerotic) aneurysms are the most common type. 2. Syphilitic (luetic) aneurysms found in the tertiary stage of the syphilis. 3. Dissecting aneurysms (Dissecting haematoma) in which the blood enters the separated or dissected wall of the vessel. 4. Mycotic aneurysms resulting from weakening of the arterial wall by microbial infection. 5. Berry aneurysms which are small dilatations especially affecting the circle of Willis in the base of the brain.
  13. 13. Pathology Etiology • Atherosclerosis especially in aortic aneurysms • Hypertension especially in ascending aortic aneurysms • Trauma • Vasculitis • Congenital defects – Fibromuscular dysplasia – Berry aneurysms typically in the circle of willis • Infections - – Syphilic aneurysms – Mycotic aneurysms – From embolization of a septic embolus - complication of infective endocarditis – As an extension of an adjacent suppurative process – By circulating organisms directly infecting the arterial wall.
  14. 14. Pathology • Occur when structure or function of the connective tissue within the vascular wall is compromised. • Poor intrinsic quality of the vascular wall connective tissue. • Imbalance in vascular wall collagen degradation and synthesis caused by inflammation and associated proteases. • Weakening of vascular wall due to – loss of smooth muscle cells – synthesis of non-collagenous /non-elastic extracellular matrix.
  15. 15. Pathology  Poor intrinsic quality of the vascular wall connective tissue – defective synthesis of fibrillin leads to aberrant TGF-β activity and weakening of elastic tissue in the aorta, this may result in progressive dilation in Marfan syndrome. – mutations in TGF-β receptors lead to defective synthesis of elastin and collagens I and II in Loeys-Dietz syndrome. – Weak vessel walls due to defective type III collagen synthesis are also a hallmark of the vascular forms of Ehlers-Danlos syndrome. – altered collagen cross-linking associated with Vitamin C deficiency (scurvy)
  16. 16. Pathology Imbalance in vascular wall collagen degradation & synthesis • Increased matrix metalloprotease (MMP) expression, especially by macrophages in atherosclerotic plaque or in vasculitis degrade virtually all components of the extracellular matrix in the arterial wall (collagens, elastin, proteoglycans, laminin, fibronectin). • Decreased expression of tissue inhibitors of metalloproteases (TIMPs) • May be associated with MMP & TIMP polymorphisms.
  17. 17. Pathology Weakening of vascular wall • Ischemia of the inner media occurs when there is atherosclerotic thickening of the intima. • Systemic hypertension causes significant narrowing of arterioles of the vasa vasorum. • Medial ischemia may lead to “degenerative changes” of the aorta. • Smooth muscle cell loss/change in synthetic phenotype leads to scarring (and loss of elastic fibers), inadequate extracellular matrix synthesis, and production of increasing amounts of amorphous ground substance (glycosaminoglycan).
  18. 18. Pathology
  19. 19. ATHEROSCLEROTIC ANEURYSMS • Most common form of aortic aneurysms. • More commonly seen in males over the age of 50 years. • Most common sites abdominal aorta, thoracic aorta, iliac arteries and other large systemic arteries. • Pathogenesis :
  20. 20. ATHEROSCLEROTIC ANEURYSMS
  21. 21. External view, gross photograph of a large aortic aneurysm that ruptured Opened view, with location of rupture tract indicated by a probe. The wall of the aneurysm is exceedingly thin, with lumen filled by large uantity of layered but largely unorganized thrombus
  22. 22. ATHEROSCLEROTIC ANEURYSMS COMPLICATIONS : 1. Rupture • Most serious and fatal complication. • Depends upon the size and duration of the aneurysm and the blood pressure. • Rupture of abdominal aneurysm may occur either into the peritoneum or into the retroperitoneum resulting in sudden and massive bleeding. • Occasionally, there may be slow progressive leak from the aneurysm. • A ruptured aneurysm is more likely to get infected. 2. Compression • The atherosclerotic aneurysm may press upon some adjacent structures such as compression of ureter and erosion on the vertebral bodies. 3. Arterial occlusion • Atherosclerotic aneurysms of the abdominal aorta may occlude the inferior mesenteric artery, or there may be development of occlusive thrombosis. • Collateral circulation develops slowly and is nearly always sufficient so as not to produce effects of ischaemia. • Thromboembolism is rather common in abdominal aneurysms.
  23. 23. Obliterative endarteritis: • Luminal narrowing and obliteration, scarring of the vessel wall, and a dense surrounding rim of lymphocytes and plasma cells that may extend into the media • The aorta loses its elastic recoil with destruction of the media and becomes dilated, producing an aneurysm. • Valvular insufficiency and massive volume overload lead to hypertrophy of the left ventricle. • The greatly enlarged hearts are sometimes called "cor bovinum" (cow's heart).
  24. 24. COMPLICATIONS 1. Rupture • Causes massive and fatal haemorrhage into the pleural cavity, pericardial sac, trachea and oesophagus. 2. Compression • The aneurysm may press on the adjacent tissues and cause symptoms :  on trachea causing dyspnoea,  on oesophagus causing dysphagia,  on recurrent laryngeal nerve leading to hoarseness  and erosion of vertebrae, sternum and ribs due to persistent pressure. 3. Cardiac dysfunction • When the aortic root and valve are involved, syphilitic aneurysm produces aortic incompetence and cardiac failure. • Narrowing of the coronary ostia may further aggravate cardiac disease.
  25. 25. Dissecting aneurysm of the aorta (Aortic dissection) • Refers to a dissecting haematoma in which the blood enters the separated (dissected) wall of the vessel and spreads for varying distance longitudinally. • The most common site is the aorta and is an acute catastrophic aortic disease. • The condition occurs most commonly in men in the age range of 50 to 70 years. • In women, dissecting aneurysms may occur during pregnancy.
  26. 26. Dissecting aneurysm of the aorta (Aortic dissection) The aortic wall has split (dissected) at the level of the media producing an outer false lumen running parallel to the central true lumen which is narrowed.
  27. 27. Dissecting aneurysm of the aorta (Aortic dissection) PATHOGENESIS 1. Hypertension in about 90% cases of dissecting aneurysm. 2. Marfan’s syndrome 3. Development of cystic medial necrosis of Erdheim, especially in old age. 4. Iatrogenic trauma during cardiac catheterisation or coronary bypass surgery 5. Pregnancy, for some unknown reasons
  28. 28. Dissecting aneurysm of the aorta (Aortic dissection) CLASSIFICATION
  29. 29. Dissecting aneurysm of the aorta (Aortic dissection) HISTOLOGY i. Focal separation of the fibromuscular and elastic tissue of the media. ii. Numerous cystic spaces in the media containing basophilic ground substance. iii. Fragmentation of the elastic tissue. iv. Increased fibrosis of the media.
  30. 30. Dissecting aneurysm of the aorta (Aortic dissection) COMPLICATIONS 1. Rupture • Haemorrhage from rupture results in mortality in 90% of cases. • Haemorrhage occurs into the pericardium; less frequently it may rupture into thoracic cavity, abdominal cavity or retroperitoneum. 2. Cardiac disease • Involvement of the aortic valve results in aortic incompetence. • Obstruction of coronaries results in ischaemia causing fatal myocardial infarction. • Rarely, dissecting aneurysm may extend into the cardiac chamber. 3. Ischaemia • Obstruction of the branches of aorta by dissection results in ischaemia of the tissue supplied. • There may be renal infarction, cerebral ischaemia and infarction of the spinal cord.
  31. 31. To summarize… • An aneurysm is a permanent abnormal dilatation of a blood vessel due to congenital or acquired weakening or destruction of the vessel wall. • ŒBased on pathogenetic mechanisms, aneurysms are atherosclerotic, syphilitic (luetic), dissecting, mycotic and berry aneurysms; the last ones are seen in the circle of Willis in the base of the brain. • ŒAtherosclerotic aneurysms are the most common,affecting abdominal aorta more often and may rupture or cause compression on adjacent tissues. • Syphilitic aneurysm occurs due to syphilitic aortitis and affects ascending and arch of aorta. • Dissecting haematoma is often preceded by hypertension and affects the arch and ascending aorta most often.

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