abdominal aortic aneurysms basic science april 12, 2006

Abdominal Aortic AneurysmsAbdominal Aortic Aneurysms

Basic ScienceBasic Science

April 12, 2006April 12, 2006

1. What is true concerning the 1. What is true concerning the presentation of AAAs?presentation of AAAs?

A.A. Most AAAs are asymptomatic when first Most AAAs are asymptomatic when first discovered.discovered.B.B. Up to half of all AAAs are found Up to half of all AAAs are found incidentally by a radiological study.incidentally by a radiological study.C.C. When symptomatic, AAAs usually present When symptomatic, AAAs usually present as vague abdominal or back pain.as vague abdominal or back pain.D.D. Severe abdominal/back pain with Severe abdominal/back pain with tenderness of the aneurysm warrants urgent tenderness of the aneurysm warrants urgent repair.repair.E.E. Up to 5% of all AAAs present for the first Up to 5% of all AAAs present for the first time with acute rupture.time with acute rupture.

80% are found incidentally by U/S, CT, MRI, or 80% are found incidentally by U/S, CT, MRI, or xray.xray.

Up to 12% present for the first time with rupture.Up to 12% present for the first time with rupture.

Acutely expanding aneurysms produce severe, Acutely expanding aneurysms produce severe, deep back pain or abdominal pain radiating to deep back pain or abdominal pain radiating to the back. This may be accompanied by the back. This may be accompanied by tenderness to palpation of the aneurysm. This tenderness to palpation of the aneurysm. This presentation often precedes rupture and urgent presentation often precedes rupture and urgent treatment is required.treatment is required.

2. When diagnosing AAAs:2. When diagnosing AAAs:

A.A. Ultrasound is too user dependent and Ultrasound is too user dependent and unreliable to use as a method for diagnosis and unreliable to use as a method for diagnosis and subsequent follow up of AAAs.subsequent follow up of AAAs.B.B. CT scan is the most precise test for CT scan is the most precise test for imaging AAAs and can give information about imaging AAAs and can give information about the renal vasculature for pre-operative planning.the renal vasculature for pre-operative planning.C.C. MRI is less sensitive than CT in identifying MRI is less sensitive than CT in identifying accessory renal arteries and grading stenoses.accessory renal arteries and grading stenoses.D.D. Arteriography remains an accurate tool to Arteriography remains an accurate tool to assess the size and extent of AAA disease.assess the size and extent of AAA disease.E.E. Physical exam alone is not sufficient to Physical exam alone is not sufficient to assess AAA disease.assess AAA disease.

U/S is the most widely used modality to diagnose and U/S is the most widely used modality to diagnose and follow-up AAA disease. It is less useful as a pre-follow-up AAA disease. It is less useful as a pre-operative planning tool due to its inability to accurately operative planning tool due to its inability to accurately assess the renal and iliac vasculature.assess the renal and iliac vasculature.MRI is a viable option to CT, especially in the renal MRI is a viable option to CT, especially in the renal impaired population where contrast is a concern.impaired population where contrast is a concern.Arteriography has largely been supplanted by CT Arteriography has largely been supplanted by CT scanning. Although it still has its uses, it cannot scanning. Although it still has its uses, it cannot accurately measure the size of the aneurysm since only accurately measure the size of the aneurysm since only the lumen (and not clot) will be visible.the lumen (and not clot) will be visible.Physical exam is more accurate in thin patients with Physical exam is more accurate in thin patients with large aneurysms. Since this isn’t the typical patient large aneurysms. Since this isn’t the typical patient population, PE may result in 50% false positive and population, PE may result in 50% false positive and negative rates.negative rates.

3. What is the most important factor 3. What is the most important factor to consider in a patient who is to consider in a patient who is about to undergo AAA repair?about to undergo AAA repair?

A.A. Age.Age.

B.B. Cardiac status.Cardiac status.

C.C. Pulmonary status.Pulmonary status.

D.D. Renal status.Renal status.

E.E. Mental status.Mental status.

With the advent of endovascular repair age alone With the advent of endovascular repair age alone is no longer a reason to deny repair.is no longer a reason to deny repair.Uncorrected CAD increases the risk of Uncorrected CAD increases the risk of mortality/morbidity significantly, with a 4.7% risk of mortality/morbidity significantly, with a 4.7% risk of fatal MI and 16% risk of non-fatal MI. Any patient fatal MI and 16% risk of non-fatal MI. Any patient found to have significant CAD should undergo found to have significant CAD should undergo catheterization first before elective AAA repair.catheterization first before elective AAA repair.Pulmonary and renal function are also important, Pulmonary and renal function are also important, especially when determining the use of contrast especially when determining the use of contrast material, and should be optimized pre-operatively.material, and should be optimized pre-operatively.

4. Criteria for operative repair 4. Criteria for operative repair include:include:

A.A. Size of the AAA; anything greater than 4.5 cm Size of the AAA; anything greater than 4.5 cm should be repaired due to higher risk of rupture.should be repaired due to higher risk of rupture.B.B. Rate of growth; greater than 1 cm growth in a 6 Rate of growth; greater than 1 cm growth in a 6 month period warrants repair.month period warrants repair.C.C. Symptoms; abdominal or back pain originating Symptoms; abdominal or back pain originating from a rapidly expanding aneurysm warrants urgent from a rapidly expanding aneurysm warrants urgent repair.repair.D.D. Endovascular repair only for all patients over the Endovascular repair only for all patients over the age of 85.age of 85.E.E. Mental status; no repair warranted for those with Mental status; no repair warranted for those with dementia or psychiatric issues due to poor follow-up.dementia or psychiatric issues due to poor follow-up.

In generalIn general AAAs greater than 5.5 cm should be AAAs greater than 5.5 cm should be repaired (of course each patient is different – i.e. repaired (of course each patient is different – i.e. tiny little old lady with 4.5 cm AAA).tiny little old lady with 4.5 cm AAA).

Growth of 0.5 cm or more in 6 months warrants Growth of 0.5 cm or more in 6 months warrants repair.repair.

Endovascular repair should only be done for Endovascular repair should only be done for proper candidates with adequate anatomy.proper candidates with adequate anatomy.

MS is not a contraindication for repair.MS is not a contraindication for repair.

5. In open repair of AAAs:5. In open repair of AAAs:

A.A. Transperitoneal or retroperitoneal Transperitoneal or retroperitoneal approaches may be used with similar outcomes.approaches may be used with similar outcomes.B.B. The IMA should be carefully re-implanted The IMA should be carefully re-implanted to the graft at the end of each case.to the graft at the end of each case.C.C. Only tube grafts are covered with the Only tube grafts are covered with the aortic sac vs. bifurcated grafts where the sac is aortic sac vs. bifurcated grafts where the sac is completely removed.completely removed.D.D. Long lasting absorbable sutures (i.e. PDS) Long lasting absorbable sutures (i.e. PDS) should be used to prevent suture granulomas at should be used to prevent suture granulomas at the anastomotic site.the anastomotic site.E.E. All backbleeding lumbar arteries are All backbleeding lumbar arteries are oversewn once the mural thrombus is removed.oversewn once the mural thrombus is removed.

The retroperitoneal approach is useful in The retroperitoneal approach is useful in patients with a hostile abdomen. The patients with a hostile abdomen. The transperitoneal approach gives greater exposure transperitoneal approach gives greater exposure to the right renal artery and right iliacs.to the right renal artery and right iliacs.The IMA may be ligated with good backbleeding.The IMA may be ligated with good backbleeding.All grafts should be covered to prevent All grafts should be covered to prevent aortoenteric fistulas and other adhesive aortoenteric fistulas and other adhesive complications.complications.Non-absorbable monofilament sutures should be Non-absorbable monofilament sutures should be used.used.

6. Concerning endovascular repair 6. Concerning endovascular repair of AAAs:of AAAs:

A.A. The graft is deployed via the femoral The graft is deployed via the femoral arteries percutaneously.arteries percutaneously.B.B. Most grafts are bifurcated self-expanding Most grafts are bifurcated self-expanding stents in two pieces: the main body and a limb.stents in two pieces: the main body and a limb.C.C. Technical success rate for the procedure Technical success rate for the procedure is ~90%.is ~90%.D.D. Contraindications include a short proximal Contraindications include a short proximal infrarenal neck (<1.5 cm) and excessively infrarenal neck (<1.5 cm) and excessively tortuous iliac arteries.tortuous iliac arteries.E.E. Long term survival thus far is comparable Long term survival thus far is comparable to open repair.to open repair.

The procedure requires cut down of the femoral The procedure requires cut down of the femoral arteries.arteries.

The technical success rate reported in the The technical success rate reported in the literature is excellent, in the range of 99-100%.literature is excellent, in the range of 99-100%.

The benefits of this procedure are decreased The benefits of this procedure are decreased blood loss, quicker recovery, and lesser blood loss, quicker recovery, and lesser morbidity with shorter stay in the hospital, and it morbidity with shorter stay in the hospital, and it may be applicable to high-risk patients.may be applicable to high-risk patients.

7. A patient with a known history of AAA 7. A patient with a known history of AAA arrives in the ER with abdominal pain, is arrives in the ER with abdominal pain, is

diaphoretic, and hypotensive with MS diaphoretic, and hypotensive with MS changes. The next step in management is:changes. The next step in management is:

A.A. ECG to rule out a MI.ECG to rule out a MI.B.B. STAT blood work to check the Hct.STAT blood work to check the Hct.C.C. Immediate CT scan to r/o AAA rupture.Immediate CT scan to r/o AAA rupture.D.D. Transfer to the SICU for resuscitation.Transfer to the SICU for resuscitation.E.E. Boluses of 4 units of blood and 2 L Boluses of 4 units of blood and 2 L crystalloid to raise the SBP >120.crystalloid to raise the SBP >120.F.F. Direct trip to the OR for exploration and Direct trip to the OR for exploration and AAA repair.AAA repair.

AAAs can rupture anteriorly resulting in free AAAs can rupture anteriorly resulting in free intraperitoneal rupture, or retroperitoneally, often intraperitoneal rupture, or retroperitoneally, often resulting in a contained rupture.resulting in a contained rupture.

In cases of free rupture, patients often present In cases of free rupture, patients often present with abdominal/back pain and hemodynamic with abdominal/back pain and hemodynamic instability, requiring immediate operation without instability, requiring immediate operation without any further workup. Resuscitating these patients any further workup. Resuscitating these patients too aggressively without correcting the rupture too aggressively without correcting the rupture results in further bleeding, hemodilution, and results in further bleeding, hemodilution, and coagulopathy.coagulopathy.

The mortality in free rupture with shock The mortality in free rupture with shock remains extremely high: ~90%. The remains extremely high: ~90%. The deaths usually occur in the ICU after the deaths usually occur in the ICU after the operation.operation.

The mortality in contained ruptures is The mortality in contained ruptures is <50%.<50%.

8. The mortality rate after elective 8. The mortality rate after elective AAA repair is:AAA repair is:

A.A. 0-5% in leading centers for open 0-5% in leading centers for open repair.repair.

B.B. 5-10% for open repair population 5-10% for open repair population wide.wide.

C.C. 0-1% for endovascular repair.0-1% for endovascular repair.

D.D. 5-10% for inflammatory aneurysms 5-10% for inflammatory aneurysms and rapidly expanding aneurysms and rapidly expanding aneurysms presenting with abdominal/back pain.presenting with abdominal/back pain.

The mortality rate for endovascular repair The mortality rate for endovascular repair is 1-3%, comparable to that of well is 1-3%, comparable to that of well selected open patients.selected open patients.

9. The most frequent complication 9. The most frequent complication of AAA repair is:of AAA repair is:

A.A. Peripheral embolization to the lower Peripheral embolization to the lower extremities.extremities.

B.B. Colonic ischemia.Colonic ischemia.

C.C. Myocardial infarction.Myocardial infarction.

D.D. Paraplegia.Paraplegia.

E.E. Sexual dysfunction.Sexual dysfunction.

All of the above are known complications of AAA All of the above are known complications of AAA repair, with MI being the most common at 3-16% repair, with MI being the most common at 3-16% and paraplegia least common (0.2%).and paraplegia least common (0.2%).““Colon ischemia occurs after 1% of aneurysm Colon ischemia occurs after 1% of aneurysm repairs and presents with bloody diarrhea, repairs and presents with bloody diarrhea, abdominal pain, and distention and leukocytosis abdominal pain, and distention and leukocytosis with findings of mucosal sloughing on with findings of mucosal sloughing on sigmoidoscopy. In case of transmural colonic sigmoidoscopy. In case of transmural colonic necrosis, colon resection and exteriorization of necrosis, colon resection and exteriorization of stomas are warranted. Mortality rate in patients stomas are warranted. Mortality rate in patients with colon ischemia is 50% and increases to with colon ischemia is 50% and increases to 90% when full-thickness gangrene and 90% when full-thickness gangrene and peritonitis have developed.”peritonitis have developed.”

10. Match the appropriate endoleak 10. Match the appropriate endoleak definitions.definitions.

A.A. Type IType I

B.B. Type IIType II

C.C. Type IIIType III

D.D. Type IVType IV

A.A. Attachment site.Attachment site.

B.B. Collateral Collateral circulation.circulation.

C.C. Fabric tear or Fabric tear or module interface.module interface.

D.D. Transgraft.Transgraft.

Type I and III endoleaks usually require Type I and III endoleaks usually require correction due to risk of aneurysmal growth and correction due to risk of aneurysmal growth and rupture. Correction normally entails balloon rupture. Correction normally entails balloon angioplasty or deployment of a modular angioplasty or deployment of a modular extender cuff at the site of leak.extender cuff at the site of leak.Type II endoleaks can be treated with Type II endoleaks can be treated with embolization of the collateral vessel.embolization of the collateral vessel.Type IV endoleaks are benign and self-limited, Type IV endoleaks are benign and self-limited, usually seen as a blush at completion usually seen as a blush at completion ateriography, and warrant ruling out the more ateriography, and warrant ruling out the more worrisome type I endoleak.worrisome type I endoleak.

11. When repair of a AAA is 11. When repair of a AAA is complicated with a concurrent complicated with a concurrent

disease:disease:A.A. All other diseases should always be dealt All other diseases should always be dealt with first and the AAA repaired once the patient with first and the AAA repaired once the patient is fully optimized.is fully optimized.B.B. The most life threatening disease needs to The most life threatening disease needs to be dealt with first, and if more than one disease be dealt with first, and if more than one disease exists then both should be dealt with exists then both should be dealt with concomitantly.concomitantly.C.C. A ruptured or symptomatic AAA normally A ruptured or symptomatic AAA normally takes precedence over other concurrent disease takes precedence over other concurrent disease processes.processes.D.D. Endovascular repair is contraindicated in Endovascular repair is contraindicated in patients with concurrent abdominal disease patients with concurrent abdominal disease processes.processes.

The most common disease entities that The most common disease entities that coexist with aortic aneurysms include coexist with aortic aneurysms include hepatobiliary, pancreatic, gastrointestinal, hepatobiliary, pancreatic, gastrointestinal, gynecologic, and genitourinary disorders gynecologic, and genitourinary disorders and structural abnormalities of the and structural abnormalities of the abdominal wall.abdominal wall.Endovascular aneurysm repair can avoid Endovascular aneurysm repair can avoid concomitant intra-abdominal problems, but concomitant intra-abdominal problems, but it will not resolve intestinal obstruction or it will not resolve intestinal obstruction or other life-threatening conditions.other life-threatening conditions.

12. Regarding horseshoe kidneys 12. Regarding horseshoe kidneys in AAA repair:in AAA repair:

A.A. Endovascular repair is contraindicated Endovascular repair is contraindicated in patients with horseshoe kidneys.in patients with horseshoe kidneys.B.B. Up to 3% of the general population Up to 3% of the general population have horseshoe kidneys.have horseshoe kidneys.C.C. Renal arteries arising from the Renal arteries arising from the aneurysm should be reimplanted to aneurysm should be reimplanted to preserve renal function.preserve renal function.D.D. The anterior approach is The anterior approach is contraindicated in patients with horseshoe contraindicated in patients with horseshoe kidneys.kidneys.

Endovascular repair can be done in the Endovascular repair can be done in the normal fashion for patients with horseshoe normal fashion for patients with horseshoe kidneys who have appropriate anatomy.kidneys who have appropriate anatomy.

0.3% of the population have horseshoe 0.3% of the population have horseshoe kidneys.kidneys.

Although the anterior approach may be Although the anterior approach may be used, the retroperitoneal approach is still used, the retroperitoneal approach is still preferable in patients with horseshoe preferable in patients with horseshoe kidneys.kidneys.

13. Inflammatory AAAs:13. Inflammatory AAAs:

A.A. Account for 5% of all AAAs.Account for 5% of all AAAs.

B.B. Present initially as ruptured AAAs Present initially as ruptured AAAs more often than non-inflammatory AAAs.more often than non-inflammatory AAAs.

C.C. Often present with flank/abdominal Often present with flank/abdominal pain with associated weight loss and pain with associated weight loss and elevated ESR.elevated ESR.

D.D. Ureters may be involved resulting in Ureters may be involved resulting in urinary symptoms.urinary symptoms.

Rupture of inflammatory AAAs is unusual. Rupture of inflammatory AAAs is unusual. This is mainly because patients present This is mainly because patients present with symptoms much earlier than non-with symptoms much earlier than non-inflammatory AAAs.inflammatory AAAs.

Whether the inflammatory process Whether the inflammatory process provides a protective effect is not known. provides a protective effect is not known.

End.End.

abdominal aortic aneurysms basic science april 12, 2006

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