Arterial Aneurysms Vascular Surgery Course For MRCS Military Academy, Thursday 18.08.05.

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Arterial Aneurysms Vascular Surgery Course For MRCS Military Academy, Thursday 18.08.05

Transcript of Arterial Aneurysms Vascular Surgery Course For MRCS Military Academy, Thursday 18.08.05.

Arterial Aneurysms

Vascular Surgery Course For MRCS

Military Academy, Thursday 18.08.05

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 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%

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