Perioperative management - Endoaneurysmorrhaphy with intraluminal straight graft placement in infrarenal abominal aortic aneurysm - Vascular Surgery

The indication for open repair of abdominal aortic aneurysm (AAA) basically results from comparing the patient's individual risk of rupture in the spontaneous course of the disease with the risk of open surgery. If the risk of spontaeous rupture over the course exceeds the individual surgical risk, open surgery is usually indicated.

Rupture risk classification

 Indication for surgery

 There are two types of repair in AAA:

• open replacement of the abdominal aorta with a straight (tubular) or bifurcation graft (OAR, open aortic repair)
• endovascular placement of a stent graft (EVAR, endovascular aortic repair)

Laparoscopic aneurysm repair surgery, usually performed in combination with mini-laparotomy, is of lesser importance.

The following recommendations serve as a guide to choosing between OAR and EVAR:

OAR (trans-/retroperitoneal)

• Normal life expectancy
• Low surgical risk (fitness)
• Anatomy unsuitable for EVAR: landing zone; aneurysm neck (angle, length); iliac vessels (stenosis, elongation, kinking); thrombi; calcification
• Marfan and other connective tissue disorders

EVAR (standard /customized graft)

• Prior abdominal surgery
• Limited life expectancy
• High surgical risk
• Anatomy suitable for EVAR (see above)

Since stent graft systems are often of large caliber, EVAR requires adequate iliac artery lumen for access. Iliac arteries with atherosclerotic stenosis, tortuosity, kinking, or aneurysmal dilation are a problem.

In the long run, endovascular aortic grafts are associated with a higher complication rate than open aortic surgery.

The BAR Score Calculator -> www.britishaneurysmrepairscore.com can quickly calculate patient mortality risk for EVAR or OAR, which can be useful when advising patients about the risk of elective EVAR or OAR.

Video example:

Asymptomatic infrarenal AAA greater than 5 cm in diameter do not lend themselves to EVAR due to aneurysmal neck angulation greater than 60°.

Contraindications for open aneurysm repair:

• Serious cardiopulmonary risks (e.g. NYHA IV, COPD Gold stage IV)
• Acute or chronic inflammatory abdominal conditions (e.g., florid ulcerative colitis, recurrent sigmoid diverticulitis)
• History of multiple extensive abdominal procedures ("hostile abdomen")
• Cirrhosis of the liver
• Advanced tumor disease
• Compensated renal failure (relative contraindication)

Medical history

• Cardiac history
• Medication history
• Risk factors: nicotine abuse; arterial hypertension; coronary heart disease; cardiac failure; diabetes; manifest renal failure with/without dialysis; coagulopathy
• Walking distance/claudication
• Back or side pain?
• Mesogastric and upper quadrant complaints?

Inspection

• Skin changes
• Muscular abnormalities
• Orthopedic malalignment
• Skin color
• Body hair
• Trophic changes
• Swelling; edema; mycosis; phlegmon; leg ulcers    

Palpation

• Bilateral comparison of pulse status
• Bilateral comparison of skin temperature
• Possibly expansive pulsating mesogastric tumor
• Pasty painful abdomen with large pulsating mass: Suspected contained rupture

Auscultatory bilateral comparison of the limb arteries

Ankle-Brachial Index (ABI)

• ABI = systolic BP of posterior tibial artery / systolic BP of brachial artery

• ABI < 0.9 is considered evidence of significant PAD.
• Determining the ankle-brachial index (ABI) through non-invasive Doppler occlusion pressure measurement is a suitable test for confirming PAD.
• PAD diagnosis is determined by the ABI value with the lowest ankle artery pressure.
• A pathologic ankle-brachial index is an independent risk indicator for increased cardiovascular morbidity and mortality.

Color-flow Doppler ultrasonography

• Carotid arteries, abdominal aorta, limb arteries
• Stenoses and occlusions in almost all vascular regions apart from chest
• Allows quantifying the degree of stenosis and assessing plaque morphology
• Sensitivity and specificity around 90%   
• Well suited as screening modality

Contrast-enhanced spiral computed tomography angiography (SCTA)

• Broad range of indications: traumatic vascular lesion (esp. trunk); vascular dissection/rupture; aneurysm; arterial thrombosis/embolism; portal vein/mesenteric vein thrombosis; pulmonary artery embolism; PAD; vascular tumors
• Benefits: rapid; detects relevant comorbidities; visualizes peripheral arteries; sensitivity and specificity each about 90%
• Drawbacks: Radiation and contrast agent exposure, allergies (about 3%), no functional assessment
• Aneurysm: three-dimensional imaging of the entire aorta and its morphology, sufficiently accurate dimensions for EVAR, visualizing luminal condition with thrombosis and calcification

Angiography (intra-arterial DSA)

• Visualization of aortic branches (stenoses; renal polar arteries; visceral iliac and femoral arteries)
• Dynamic visualization
• Drawbacks: limited visualization of aneurysm morphology (only patent lumen); ionizing radiation; nephrotoxic contrast agent; invasive 

Cardiac check

• Resting ECG
• Exercise ECG
• Echocardiography

Chest x-ray

Possibly spirometry

Laboratory panels

• Blood count
• Electrolytes
• Coagulation
• Kidney function parameters
• Liver function parameters
• Blood lipids
• Blood group

• Enema the evening before
• Hair cut in surgical field
• Order packed RBCs
• Foley catheter
• Administer prophylactic perioperative antibiotics 30 min. before beginning surgery (see KRINKO recommendation, Robert Koch Institute)

General surgical risks

• Allergy/intolerance (e.g., latex, medication)
• Wound infection, sepsis
• Thromboembolism
• Skin/tissue/nerve damage due to positioning on OR table or procedure-related measures
• Keloid

Specific procedural risks

• Bleeding, blood transfusions, transmission of hepatitis/HIV through allogeneic blood transusion
• Secondary bleeding, possibly requiring revision surgery
• Thrombosis of the graft and possibly adjacent vascular segments; hypoperfusion of the legs; gangrene; limb loss/amputation; revision surgery
• Injury of adjacent organs (e.g. ureter; urinary bladder; bowel; kidneys; etc.), repeat surgery
• Kidney failure secondary to preexisting renal insufficiency or additional renal artery interventions, possibly ESRD
• Nerve injury with dysesthesia or pain; weakness of abdominal muscles; weakness or partial paralysis of thigh muscles; each of which may be temporary or permanent
• In men: sexual dysfunction, infertility in case of vas deferens injury, and non-functional contralateral vas deferens
• Impaired perfusion of the bowel/ischemic colitis, possibly resection, temporary or permanent stoma
• Spinal ischemia/paraplegia
• Abdominal compartment syndrome:  Multi-organ failure, intensive care medicine, relaparotomy
• Lymphedema, temporary or permanent
• Infection-induced graft suture breakage: bleeding, sepsis, relaparotomy
• Side effects of iodine-containing contrast media
• Suture aneurysm, surgical revision, possibly endovascular
• Incisional hernia
• Intra-abdominal adhesions