Arterial Aneurysms Vascular Surgery Course For MRCS Military Academy, Thursday

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)

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

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

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

Rare causes of aneurysms Mycotic –Bacterial endocarditis, syphilis Pregnancy associated –Splenic, cerebral, aortic, renal, iliac & coronary

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

Incidence- atherosclerotic >90% affecting abdominal aorta Infra-renal segment in ~95% Male : Female ratio4:1 More common in western countries 5% over 50s, 15% over 80s Associated with iliac aneurysms in 30% Associated with popliteal aneurysms in 10%

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

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

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

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

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

Investigation CXR, PFT ECG, Echo ESR U&Es USS Spiral CT with contrast Arteriography

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%

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

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

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)

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

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

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

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

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

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

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

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

answers 1- A 2- ABD 3- DE