aneurysm

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aneurysm

  1. 1. Arterial Aneurysms Vascular Surgery Course For MRCS Military Academy, Thursday 18.08.05
  2. 2. Definition Permanent localized dilatation of the affected artery over the normal diameter ~ 50% Arteriomegaly ~ 100% Aneurysms As the age increases, arteries become stiffer, wider (aneurysm) and longer (tortousity)
  3. 3. Aetiology • Most aneurysms are caused by degenerative disease affecting the vessel (atherosclerosis) • Structural weakness & Haemodynamic forces – Damage to, and loss of intima – Reduction in the elastin and collagen content of the media – Collagen; tensile strength, adventitia – Elastin; recoil capacity, media • Risk factors – smoking, hypertension, hypercholesterolaemia
  4. 4. Aetiology • Laplace’s low (Tension varies directly with radius when pressure is constant) – For every increase in the radius there is a large increase in tension, leading to further enlargement of the aneurysm
  5. 5. Rare causes of aneurysms • Congenital – Marfan’s syndrome, Berry aneurysms • Post-stenotic – Coarctation of the aorta, Cervical rib, Popliteal artery entrapment syndrome • Traumatic – Gunshot, stab wounds, arterial punctures • Inflammatory – Takayaso’s disease, Behcet’s disease
  6. 6. Rare causes of aneurysms • Mycotic – Bacterial endocarditis, syphilis • Pregnancy associated – Splenic, cerebral, aortic, renal, iliac & coronary
  7. 7. Classification • False – Due to traumatic breach in the wall – The sac made up from the compressed surrounding tissue • True – Dilatation involving all layers of the wall • Fusiform – Spindle-shaped involving whole circumference • Saccular – Small segment of wall ballooning due to localized weakness
  8. 8. Incidence- atherosclerotic • >90% affecting abdominal aorta • Infra-renal segment in ~95% • Male : Female ratio 4:1 • More common in western countries • 5% over 50s, 15% over 80s • Associated with iliac aneurysms in 30% • Associated with popliteal aneurysms in 10%
  9. 9. Anatomy of the abdominal aorta • Begins at T12, Ends at L4 • Anterior relations – Splenic vein, pancreas, duodenum • Right – Cisterna chyli, IVC, azygos vein • Left – Sympathetic trunk • Surface anatomy – Just above transpyloric plane in the mid line to a point left to the midline on the supracristal plane
  10. 10. • Paired visceral branches – Suprarenal, renal, gonadal • Unpaired visceral branches – Coeliac, SMA, IMA • Paired abdominal wall branches – Subcostal, inferior phrenic,lumber branches of the abdominal aorta
  11. 11. Clinical features of AAA • Asymptomatic in 75% – Incidentally discovered during clinical exam.or radiographic investigation • Pain – Central abdominal radiating to the back – Chronic due to stretching the vessel wall or compression/erosion of surrounding structures – Acute pain due to rupture
  12. 12. Clinical features of AAA • Rupture – Risk of rupture correlate with aneurysm size – Retroperitoneal, back pain, stable – Intraperitoneal, abdo/back/falnk pain, shock – 5-year rupture rate 0% in AAA <5cm – 5-year rupture rate 25% in AAA >5cm • Risk of rupture can be predicted by – High diastolic BP, COAD
  13. 13. Complications of AAA • Fistulation, rare – Gut, IVC, left renal vein • Thrombosis, rare – Acute lower limb ischaemia • Distal embolism – Acute ischaemia to small distal areas (trash foot) • Distal obliteration – Claudication, rest pain, gangrene
  14. 14. Investigation • CXR, PFT • ECG, Echo • ESR • U&Es • USS • Spiral CT with contrast • Arteriography
  15. 15. Management of AAA • Elective repair for AAA >6cm – Mortality 5% • Urgent repair for AAA <6cm – Developed back pain – Rate of growth >0.5cm / 6 month • Emergency repair for ruptured AAA – Mortality 50%
  16. 16. Elective surgical repair • 6-unit X-matched blood • Mid line or transverse incision • Aneurysm neck defined and controlled • Control of normal vessels distal to AAA • Systemic heparinization, 5000IU • AAA sac opened and thrombus removed • Back bleeding from lumber arteries controlled by sutures • Inlay tube or trouser synthetic graft • Closure of aneurysm sac over graft
  17. 17. Emergency surgical repair • Unstable patient, no investigation • Stable patient, USS/spiral CT • 10-unit of x-matched blood • Urinary catheter & 2 large-bore i.v. lines • Resustation to systolic BP ~100mmHg • Crash anaesthetic induction • No heparinization • Rapid entrance to abdomen & neck control – If difficult, supra-renal clamp for short period
  18. 18. Complications of aortic surgery • Haemorrhage, DIC • CVA • Colonic ischaemia spinal cord ischaemia • Aorto-enteric fistula • Graft thrombosis • Myocardial ischaemia • Renal failure, ARDS, MODS • False anastomotic aneurysm • Distal embolism (trash foot)
  19. 19. Endovascular repair of AAA • Patient unfit for surgical repair – severe cardio-pulmonary co-morbidities, hours shoe kidney, Inflammatory AAA, hostile abdo. • Anatomical suitability – Neck diameter & length – Iliac arteries diameter & tortousity • Morbidity – Endoleak, migration, kink, thrombosis • Mortality ~5% • Flow-up & durability
  20. 20. Inflammatory AAA • Marked fibrosis of the aneurysm wall extending to the surrounding structures • It involve the anterior and lateral aspects only • It associated with inflammatory cell infiltrate of T- , B- lymphocytes & plasma cells • The fibrosis may compress the ureters leading to renal failure • Rupture is less common and usually posterior • Pt. presents with abdo. pain, weight loss, raised ESR • Difficult surgery, therefore conservative/endovascular
  21. 21. popliteal aneurysms • Second most common site of atherosclerotic aneurysms • Occasionally, present with pulsatile swelling • Commonly, aneurysm thrombosis or distal emboli leading to peripheral ischaemia • USS/CT/Arteriography to confirm diagnosis • Surgical repair, resection/ligation and vein bypass • 40% of pts with PA aneurysms have an AAA
  22. 22. Femoral aneurysms • Can occur in isolation but usually part of generalized arteriomegaly • Often symptomless and rarely rupture • Distal emboli & thrombosis may occur • Surgical repair by using vein or synthetic graft
  23. 23. Splenic aneurysms • Male : female 1 : 4 • It present in child bearing period • Usually symptomless unless ruptured • Rupture rate 25% in the third trimester • Surgical treatment is indicated if the aneurysm diameter >3cm or patient is pregnant
  24. 24. 1- AAA • A- is 4 time more common in males • B- incidence is falling in western countries • C- may safely observed if asymptomatic and >5.5cm in diameter • D- is rarely amenable to endoluminal stenting • E- is less common than popliteal aneurysms
  25. 25. 2- AAA • A- may cause embolisation to lower limbs • B- is more common in males • C- can almost always be treated by endovascular stenting • D- can be detected by screening • E- should be operated upon when it is 5.5 cm long
  26. 26. 3- AAA • A- typically rupture at 4cm diameter • B- extends above the renal artery in 20% of cases • C- is invariably visible on abdominal X-ray • D- is associated with coronary artery disease • E- has an association with smoking
  27. 27. answers • 1- A • 2- ABD • 3- DE

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