Abdominal aortic aneurysm surgery

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Overview

Indications for operative repair of an abdominal aortic aneurysm include the presence of symptoms such as back pain, the presence of a rupture or contained rupture, an abdominal aortic aneurysm diameter greater than 5.5 cm, a rate of expansion of greater than 1 cm in one year, and an inflammatory or infectious etiology. Open surgical repair is favored in young patients as an elective procedure, the presence of an expanding aneurysm, symptomatic aneurysm, or ruptured aneurysm. An endovascular repair (EVAR) is favored in older patients and high risk patients or those unfit for open repair. Risk factors for postoperative morbidity and mortality include extensive atheromatous disease, mural calcification, thrombosis, juxtarenal extension of the aneurysm and the presence of inflammatory changes.

Indications for Operative Repair

• Symptoms
• Rupture/ contained rupture
• Distal emboli
• Pain or bowel obstruction
• AAA diameter > 5.5 cm
• AAA expansion > 1.0 cm in 1 year
• Inflammatory or infectious etiology

2005 ACC/AHA Practice Guidelines for the Management of Patients With Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic)-Recommendations for Symptomatic Aortic or Iliac Aneurysms (DO NOT EDIT)

Class I

"1. In patients with the clinical triad of abdominal and/or back pain, a pulsatile abdominal mass, and hypotension, immediate surgical evaluation is indicated. (Level of Evidence: B)"

"2. In patients with symptomatic aortic aneurysms, repair is indicated regardless of diameter. (Level of Evidence: C)"

2005 ACC/AHA Practice Guidelines for the Management of Patients With Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic)-Recommendations for Aortic Aneurysm Rupture (DO NOT EDIT)

Class I

"1. Patients with infrarenal or juxtarenal AAAs measuring 5.5 cm or larger should undergo repair to eliminate the risk of rupture. (Level of Evidence: B)"

"2. Patients with infrarenal or juxtarenal AAAs measuring 4.0 to 5.4 cm in diameter should be monitored by ultrasound or computed tomographic scans every 6 to 12 months to detect expansion. (Level of Evidence: A)"

Class III (No Benefit)

"1. Intervention is not recommended for asymptomatic infrarenal or juxtarenal AAAs if they measure less than 5.0 cm in diameter in men or less than 4.5 cm in diameter in women. (Level of Evidence: A)"

Class IIa

"1. Repair can be beneficial in patients with infrarenal or juxtarenal AAAs 5.0 to 5.4 cm in diameter. (Level of Evidence: B)"

"2. Repair is probably indicated in patients with suprarenal or type IV thoracoabdominal aortic aneurysms larger than 5.5 to 6.0 cm. (Level of Evidence: B)"

"3. In patients with AAAs smaller than 4.0 cm in diameter, monitoring by ultrasound examination every 2 to 3 years is reasonable. (Level of Evidence: B)"

Pre-Operative Assessment

• The ADAM trial suggested that the "biological age," as reflected by the condition of the vital organs such as the lungs, kidneys, heart was more important than the chronological age as a determinant of operative outcome.
• Patients with poor renal and pulmonary function have worse operative outcomes

  • Chronic obstructive pulmonary disease
  • Elevated creatinine concentrations
  • Electrocardiographic evidence of ischemia

• Aortic factors implicated in postoperative morbidity and mortality include:

  • Extensive atheromatous disease
  • Mural calcification
  • Thrombosis
  • Juxtarenal extension of aneurysm
  • Inflammatory aortic aneurysms
  • The increased risk resulted from:

    • Longer suprapenal clamping time
    • Need for complex dissection
    • Increased hemodynamic stresses

Surgery Options

The treatment options for asymptomatic AAA are immediate repair, surveillance with a view to eventual repair, and a conservative approach. Appropriate patient selection and estimation of the risk of rupture is important, as once rupture occurs, emergency surgery is indicated and mortality from exsanguination is high. There are currently two modes of repair available for an AAA: open aneurysm repair (OR), and endovascular aneurysm repair (EVAR).

Conservative treatment

• Smoking cessation
• Blood pressure control.
• Indicated when repair carries a high risk of mortality and is unlikely to improve life expectancy.

Surveillance

• Surveillance is indicated when the risk of repair exceeds the risk of rupture.
• Although some controversies exists around the world, most vascular surgeons would not consider repair until the aneurysm reached a diameter of 5cm.
• The threshold for repair varies slightly from individual to individual, depending on the balance of risks and benefits when considering repair versus ongoing surveillance.
• The size of an individual's native aorta may influence this, along with the presence of comorbitities that increase operative risk or decrease life expectancy.

Open Repair

An open repair is indicated in the following scenarios:

• Young patients as an elective procedure
• Expanding aneurysms
• Symptomatic aneurysms
• Ruptured aneurysms

Endovascular Repair (EVAR)

An endovascular repair (EVAR) is indicated in:

• Older patients
• High risk patients or those unfit for open repair

Advantages

Advantages of an endovascular repair over an open repair include the following:

• Lower mortality compared to open repair
• Reduced length of stay including a reduced time in intensive care unit
• Earlier return to normal activity

Disadvantages

Disadvantages of an endovascular repair compared to an open repair include the following:

• Endovascular repair requires more frequent ongoing surveillance and a higher chance of requiring an additional procedure

Complications

The most common complications related to repair of abdominal aortic aneurysm is related to cardiovascular and pulmonary status. smokers, patients with co-existent chronic obstructive pulmonary disease and coronary artery disease are more at risk of developing complications like:

• Myocardial ischemia
• Arrhythmias
• Pneumonia
• Atelectasis

Other complications include:

• Incomplete seal at proximal or distal stent attachment
• Leaking into the sac from branch vessels
• Failure of anastomosis between stent components
• Leakage through graft material
• Graft infection
• Acute renal failure
• Distal embolization
• Wound infection
• Colonic ischemia
• False aneurysm formation
• Aortoduodenal fistula
• Peri-operative bleeding

Surgery and Device Based Therapy

2011 ACCF/AHA Focused Update of the Guideline for the Management of Patients With Peripheral Artery Disease (Updating the 2005 Guideline) - Recommendations for Management of Abdominal Aortic Aneurysm (DO NOT EDIT)

Class I

1. Open or endovascular repair of infrarenal AAAs and/or common iliac aneurysms is indicated in patients who are good surgical candidates. (Level of Evidence: A)

2. Periodic long-term surveillance imaging should be performed to monitor for endoleak, confirm graft position, document shrinkage or stability of the excluded aneurysm sac, and determine the need for further intervention in patients who have undergone endovascular repair of infrarenal aortic and/or iliac aneurysms. (Level of Evidence: A)

Class IIa

1.Open aneurysm repair is reasonable to perform in patients who are good surgical candidates but who cannot comply with the periodic long-term surveillance required after endovascular repair. (Level of Evidence:C)

Class IIb

1.Endovascular repair of infrarenal aortic aneurysms in patients who are at high surgical or anesthetic risk as determined by the presence of coexisting severe cardiac, pulmonary, and/or renal disease is of uncertain effectiveness. (Level of Evidence:B)

ACC/ AHA Guidelines - Recommendations for surgery of Abdomino-thoracic surgery (DO NOT EDIT)

Class I

1. For patients with chronic dissection, particularly if associated with a connective tissue disorder, but without significant comorbid disease, and a descending thoracic aortic diameter exceeding 5.5 cm, open repair is recommended (Level of Evidence: B)

2. For patients with degenerative or traumatic aneurysms of the descending thoracic aorta exceeding 5.5 cm, saccular aneurysms, or postoperative pseudoaneurysms, endovascular stent grafting should be strongly considered when feasible(Level of Evidence: B)

3.For patients with thoracoabdominal aneurysms, in whom endovascular stent graft options are limited and surgical morbidity is elevated, elective surgery is recommended if the aortic diameter exceeds 6.0 cm, or less if a connective tissue disorder such as Marfan or Loeys-Dietz syndrome is present (Level of Evidence: C)

4. For patients with thoracoabdominal aneurysms and with end-organ ischemia or significant stenosis from atherosclerotic visceral artery disease, an additional revascularization procedure is recommended(Level of Evidence:B)

2005 ACC/AHA Practice Guidelines for the Management of Patients With Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic)-Recommendations for Visceral Artery Aneurysms (DO NOT EDIT)

Class I

"1. Open repair or catheter-based intervention is indicated for visceral aneurysms measuring 2.0 cm in diameter or larger in women of childbearing age who are not pregnant and in patients of either gender undergoing liver transplantation. (Level of Evidence: B)"

Class IIa Open repair or catheter-based intervention is probably indicated for visceral aneurysms 2.0 cm in diameter or larger in women beyond childbearing age and in men. (Level of Evidence: B)