What are the SVS treatment guidelines for unruptured abdominal aortic aneurysm (AAA)?

Answer

Even patients who do not have symptoms from their AAAs may eventually require surgical intervention because the result of medical management in this population is a mortality of 100% over time as a consequence of rupture. In addition, these patients have a potential for limb loss from peripheral embolization.

The decision to treat an unruptured AAA is based on operative risk, the risk of rupture, and the patient’s estimated life expectancy. In 2009, the Society for Vascular Surgery (SVS) published a series of guidelines for the treatment of AAAs based on these principles.^[20]

Operative risk is based on patients’ comorbidities and hospital factors (see Table 1 below). Patient characteristics, including age, sex, renal function, and cardiopulmonary disease are perhaps the most important factors. However, lower-volume hospitals and surgeons are associated with higher mortality.^[21]

Table 1. Operative Mortality Risk With Open Repair of Abdominal Aortic Aneurysm (Open Table in a new window)

</tbody>

Lowest Risk	Moderate Risk	High Risk
Age <70 y	Age 70-80 y	Age 80 y
Physically active	Active	Inactive, poor stamina
No clinically overt cardiac disease	Stable coronary disease; remote MI; LVEF >35%	Significant coronary disease; recent MI; frequent angina; CHF; LVEF < 25%
No significant comorbidities	Mild COPD	Limiting COPD; dyspnea at rest; O₂ dependency; FEV₁</td></tr>
...	Creatinine 2.0-3.0 mg/dL	...
Normal anatomy	Adverse anatomy or AAA characteristics	Creatinine >3 mg/dL
No adverse AAA characteristics	...	Liver disease (↑PT; albumin </td></tr>
Anticipated operative mortality, 1-3%	Anticipated operative mortality, 3-7%	Anticipated operative mortality, at least 5-10%; each comorbid condition adds ~3-5% mortality risk
AAA = abdominal aortic aneurysm; CHF = chronic heart failure; COPD = chronic obstructive pulmonary disease; FEV₁ = forced expiratory volume in 1 second; LVEF = left ventricular ejection fraction; MI = myocardial infarction; PT = prothrombin time.

Abdominal ultrasonography can provide a preliminary determination of the aneurysm’s presence, size, and extent. Rupture risk is in part indicated by the size of the aneurysm (see Table 2 below).

Table 2. Abdominal Aortic Aneurysm Size and Estimated Annual Risk of Rupture (Open Table in a new window)

AAA Diameter (cm)	Rupture Risk (%/y)
<4	0
4-5	0.5-5
5-6	3-15
6-7	10-20
7-8	20-40
>8	30-50
AAA = abdominal aortic aneurysm.

In addition to aneurysm diameter, factors such as sex, aneurysm expansion rate, family history, and chronic obstructive pulmonary disease (COPD) also affect the risk of rupture (see Table 3 below).

Table 3. Factors Affecting Risk of Abdominal Aortic Aneurysm Rupture (Open Table in a new window)

Factor	Low Risk	Average Risk	High Risk
Diameter	<5 cm	5-6 cm	>6 cm
Expansion	<0.3 cm/y	0.3-0.6 cm/y	>0.6 cm/y
Smoking/COPD	None, mild	Moderate	Severe/steroids
Family history	No relatives	One relative	Numerous relatives
Hypertension	Normal blood pressure	Controlled	Poorly controlled
Shape	Fusiform	Saccular	Very eccentric
Wall stress	Low (35 N/cm²	Medium (40 N/cm²	High (45 N/cm²)
Sex	...	Male	Female
COPD = chronic obstructive pulmonary disease.

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Media Gallery

Radiograph shows calcification of abdominal aorta. Left wall is clearly depicted and appears aneurysmal; however, right wall overlies spine.
On radiography, lateral view clearly shows calcification of both walls of abdominal aortic aneurysm, allowing diagnosis to be made with certainty.
CT demonstrates abdominal aortic aneurysm (AAA). Aneurysm was noted during workup for back pain, and CT was ordered after AAA was identified on radiography. No evidence of rupture is seen.
Arteriography demonstrates infrarenal abdominal aortic aneurysm. This arteriogram was obtained in preparation for endovascular repair of aneurysm.
Lateral arteriogram demonstrates infrarenal abdominal aortic aneurysm. Demonstration of superior mesenteric artery, inferior mesenteric artery, and celiac artery on lateral arteriogram is important for complete evaluation of extent of aneurysm.
Arteriogram after successful endovascular repair of abdominal aortic aneurysm.
Ultrasonogram from patient with abdominal aortic aneurysm (AAA). This aneurysm was best visualized on transverse or axial image. Patient underwent conventional AAA repair.
MRI of 77-year-old man with leg pain believed to be secondary to degenerative disk disease. During evaluation, abdominal aortic aneurysm was discovered.
Age is risk factor for development of aneurysm.
Inflammation, thinning of media, and marked loss of elastin.
Pulsatile abdominal mass.
Aneurysm with retroperitoneal fibrosis and adhesion of duodenum.
Aortic endoprosthesis (Cook aortic and aortobi-iliac endograft).
Endoaneurysmorrhaphy
Endovascular grafts.
Atheroemboli from small abdominal aortic aneurysms produce livedo reticularis of feet (ie, blue toe syndrome).
Enhanced spiral CT scans with multiplanar reconstruction and CT angiogram.
Angiography is used to diagnose renal area. In this instance, endoleak represented continued pressurization of sac.

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Table 1. Operative Mortality Risk With Open Repair of Abdominal Aortic Aneurysm

</tbody>

Lowest Risk	Moderate Risk	High Risk
Age <70 y	Age 70-80 y	Age 80 y
Physically active	Active	Inactive, poor stamina
No clinically overt cardiac disease	Stable coronary disease; remote MI; LVEF >35%	Significant coronary disease; recent MI; frequent angina; CHF; LVEF < 25%
No significant comorbidities	Mild COPD	Limiting COPD; dyspnea at rest; O₂ dependency; FEV₁</td></tr>
...	Creatinine 2.0-3.0 mg/dL	...
Normal anatomy	Adverse anatomy or AAA characteristics	Creatinine >3 mg/dL
No adverse AAA characteristics	...	Liver disease (↑PT; albumin </td></tr>
Anticipated operative mortality, 1-3%	Anticipated operative mortality, 3-7%	Anticipated operative mortality, at least 5-10%; each comorbid condition adds ~3-5% mortality risk
AAA = abdominal aortic aneurysm; CHF = chronic heart failure; COPD = chronic obstructive pulmonary disease; FEV₁ = forced expiratory volume in 1 second; LVEF = left ventricular ejection fraction; MI = myocardial infarction; PT = prothrombin time.

Table 2. Abdominal Aortic Aneurysm Size and Estimated Annual Risk of Rupture

AAA Diameter (cm)	Rupture Risk (%/y)
<4	0
4-5	0.5-5
5-6	3-15
6-7	10-20
7-8	20-40
>8	30-50
AAA = abdominal aortic aneurysm.

Table 3. Factors Affecting Risk of Abdominal Aortic Aneurysm Rupture

Factor	Low Risk	Average Risk	High Risk
Diameter	<5 cm	5-6 cm	>6 cm
Expansion	<0.3 cm/y	0.3-0.6 cm/y	>0.6 cm/y
Smoking/COPD	None, mild	Moderate	Severe/steroids
Family history	No relatives	One relative	Numerous relatives
Hypertension	Normal blood pressure	Controlled	Poorly controlled
Shape	Fusiform	Saccular	Very eccentric
Wall stress	Low (35 N/cm²	Medium (40 N/cm²	High (45 N/cm²)
Sex	...	Male	Female
COPD = chronic obstructive pulmonary disease.

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Author

Saum A Rahimi, MD, FACS Interim Chief, Assistant Professor of Surgery, Division of Vascular Surgery, Rutgers Robert Wood Johnson Medical School

Saum A Rahimi, MD, FACS is a member of the following medical societies: American College of Surgeons, Society for Vascular Surgery, Eastern Vascular Society, Vascular Society of New Jersey

Disclosure: Nothing to disclose.

Chief Editor

Vincent Lopez Rowe, MD Professor of Surgery, Program Director, Integrated Vascular Surgery Residency and Fellowship, Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, Keck School of Medicine of the University of Southern California

Vincent Lopez Rowe, MD is a member of the following medical societies: American College of Surgeons, American Surgical Association, Pacific Coast Surgical Association, Society for Clinical Vascular Surgery, Society for Vascular Surgery, Western Vascular Society

Disclosure: Nothing to disclose.

Acknowledgements

Suman Annambhotla, MD Fellow in Vascular Surgery, Northwestern University, The Feinberg School of Medicine

Suman Annambhotla, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, Association for Academic Surgery, and Society for Vascular Surgery