Vascular—Abdominal Aortic Aneurysm

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Vascular—Abdominal Aortic Aneurysm

Concept

An aneurysm is defined as a greater than 50% increase in the normal vessel diameter. Incidence in normal popula- tion ~ 2%, increase risk in patients with Peripheral Valvular Disease, coronary disease, and popliteal or femoral artery aneurysms. Also, an association with fam- ily history of AAA.

Way Question May be Asked?

“56 y/o female seen in ER with complaints of back pain, and is hypotensive and has a pulsatile epigastric mass on exam.” Rarely will get the patient with the classic triad of flank/back/abdominal pain, hypotension, and pulsatile abdominal mass. Mass is palpable above the umbilicus.

Should also be prepared to answer for the patient referred to you from the PMDs office after a routine physical exam discovers an asymptomatic pulsatile abdominal mass.

How to Answer?

In the unstable pt, you don’t have too much time to do your routine H +P:

Focused H +P while resuscitating the patient and getting them ready for the OR

Stat bedside Ultrasound

Flat or lateral abdominal (lumbar) x-ray

CT scan with IV contrast is a really bad choice here Fluids to keep SBP 90 is OK! (higher is associated

with increased risk of rupture)

T +C 6–8 U PRBC and send to OR with FFP, platelets, cryo, O-neg blood

Prep pt including neck, chest, abdomen, and thighs Do not anesthetize pt until completely prepped and

draped!!!

Xiphoid to pubis incision with knife

Get proximal control of aorta quickly:

If free intraperitoneal rupture, can consider balloon occulusion of the aorta, otherwise:

Divide hepatogastric ligament Pull stomach to left

Retract left hepatic lobe superiorly

Aortic occluded placed against aorta and com- press against spine

Distal control by clamping both iliacs Then enter retroperitoneal hematoma (often

hematoma does dissection for you)

Identify aneurysm neck and place proximal clamp in infrarenal position

Then give anesthesiologist time to catch up (lines, fluids, blood and blood products)

Don’t need systemic heparinization if ruptured Then open aneurysm, evacuate thrombus, suture

ligate any lumbars, place graft (tube graft 24 mm if iliacs non-aneurysmal)

Close peritoneum over top of graft Return to ICU

Be prepared to deal with hypothermia, acidosis, coagulopathy, renal failure, loss of pulses in an extremity, abdominal compartment syndrome, and post-op MI

Don’t perform aorto-bifem if mild ectasia/aneurys- mal dilation of iliacs (it’s just a longer operation in already unstable pt!)

In Asymptomatic Patient

Complete H +P Size of AAA by U/S

CT scan is best preoperative study for AAA evaluation Risk of rupture increases with size

Any AAA more than 5 cm in size is candidate for repair or AAA showing rapid growth (> 0–0.5 cm over 6 months) during follow-up

If ≤ 5 cm, ultrasound q 6 months

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Cardiac work-up in all pts: persantine thallium stress test

If positive finding on cardiac work-up → cardiac cath/surgery

A-line, SGC, Foley intra-op and post-op

Operative Approach

If elective, can discuss retroperitoneal approach through left flank incision:

Less post-op ileus and pain Useful in pt with prior abd surgery Easier access to suprarenal aorta Only describe if have seen this before

Harder to access right iliac through this incision Open transperitoneal approach:

Better pelvic exposure Used in cases of rupture

Careful of injuring duodenum/iliac veins/intra-op coagulopathy

Common Curveballs

Aneurysm will be suprarenal Aneurysm will be 4 cm

Asked when you will reimplant IMA (don’t need to if strong backbleeding or no backbleeding)

Pt will also have obstructing or near obstructing sig- moid colon lesion (key to answer here is size of AAA vs. how close to obstructing is colon lesion)

Pt will have had prior transverse colectomy for cancer (need to reimplant the IMA if stump pressure < 70 and check arteriogram pre-op)

Aneurysm will present in atypical fashion: embolization to the legs, inflammatory, aortacaval fistula, acute AAA thrombosis with pelvic and lower extremity ischemia

Pt will present later with: graft infection, aortoenteric fistula (ax-bifem 1st followed by ligation aorta), pseudoaneurysm at anastomosis

Being asked to describe your pre-op cardiac assessment (stress thallium)

There will be an intra-op anomaly: horseshoe kidney, retroaortic renal vein, left-sided IVC

Pt will be in shock and they will ask you if you want to get a CT or go straight to the OR (go to the OR and resuscitate en route!

Being asked what to do with pt with dementia, metasta- tic cancer, or elderly

Pt will have had prior abdominal surgery (colectomy →reimplant IMA!)

Being asked your feelings about “stent-grafts” (results good so far and done in symptomatic pts, but always be the conservative surgeon on the Oral Exam) Be prepared to deal with common post-op problems (pt

will likely have at least one of the following):

hypothermia acidosis coagulopathy

renal failure—(abdominal compartment syndrome, ATN, atheromatous debris, ureteral injury, hypovolemia—favorite question of the examiners is post-op AAA low UO!!!)

loss of pulses in an extremity abdominal compartment syndrome

ischemic left colon (reimplant IMA if stump pressure < 40 or Hartmann procedure post-op) post-op MI

spinal cord ischemia impotence

Strikeouts

Not knowing how to gain control of rupturing aorta Not prepping pt widely enough (include neck and

Vascular—Abdominal Aortic Aneurysm

Vascular—Abdominal Aortic Aneurysm

Concept

An aneurysm is defined as a greater than 50% increase in the normal vessel diameter. Incidence in normal popula- tion ~ 2%, increase risk in patients with Peripheral Valvular Disease, coronary disease, and popliteal or femoral artery aneurysms. Also, an association with fam- ily history of AAA.

Way Question May be Asked?

“56 y/o female seen in ER with complaints of back pain, and is hypotensive and has a pulsatile epigastric mass on exam.” Rarely will get the patient with the classic triad of flank/back/abdominal pain, hypotension, and pulsatile abdominal mass. Mass is palpable above the umbilicus.

Should also be prepared to answer for the patient referred to you from the PMDs office after a routine physical exam discovers an asymptomatic pulsatile abdominal mass.

How to Answer?

In the unstable pt, you don’t have too much time to do your routine H +P:

Focused H +P while resuscitating the patient and getting them ready for the OR

Stat bedside Ultrasound

Flat or lateral abdominal (lumbar) x-ray

CT scan with IV contrast is a really bad choice here Fluids to keep SBP 90 is OK! (higher is associated

with increased risk of rupture)

T +C 6–8 U PRBC and send to OR with FFP, platelets, cryo, O-neg blood

Prep pt including neck, chest, abdomen, and thighs Do not anesthetize pt until completely prepped and

draped!!!

Xiphoid to pubis incision with knife

Get proximal control of aorta quickly:

If free intraperitoneal rupture, can consider balloon occulusion of the aorta, otherwise:

Divide hepatogastric ligament Pull stomach to left

Retract left hepatic lobe superiorly

Aortic occluded placed against aorta and com- press against spine

Distal control by clamping both iliacs Then enter retroperitoneal hematoma (often

hematoma does dissection for you)

Identify aneurysm neck and place proximal clamp in infrarenal position

Then give anesthesiologist time to catch up (lines, fluids, blood and blood products)

Don’t need systemic heparinization if ruptured Then open aneurysm, evacuate thrombus, suture

ligate any lumbars, place graft (tube graft 24 mm if iliacs non-aneurysmal)

Close peritoneum over top of graft Return to ICU

Be prepared to deal with hypothermia, acidosis, coagulopathy, renal failure, loss of pulses in an extremity, abdominal compartment syndrome, and post-op MI

Don’t perform aorto-bifem if mild ectasia/aneurys- mal dilation of iliacs (it’s just a longer operation in already unstable pt!)

In Asymptomatic Patient

Complete H +P Size of AAA by U/S

CT scan is best preoperative study for AAA evaluation Risk of rupture increases with size

Any AAA more than 5 cm in size is candidate for repair or AAA showing rapid growth (> 0–0.5 cm over 6 months) during follow-up

If ≤ 5 cm, ultrasound q 6 months

Cardiac work-up in all pts: persantine thallium stress test

If positive finding on cardiac work-up → cardiac cath/surgery

A-line, SGC, Foley intra-op and post-op

Operative Approach

If elective, can discuss retroperitoneal approach through left flank incision:

Less post-op ileus and pain Useful in pt with prior abd surgery Easier access to suprarenal aorta Only describe if have seen this before

Harder to access right iliac through this incision Open transperitoneal approach:

Better pelvic exposure Used in cases of rupture

Careful of injuring duodenum/iliac veins/intra-op coagulopathy

Common Curveballs

Aneurysm will be suprarenal Aneurysm will be 4 cm

Asked when you will reimplant IMA (don’t need to if strong backbleeding or no backbleeding)

Pt will also have obstructing or near obstructing sig- moid colon lesion (key to answer here is size of AAA vs. how close to obstructing is colon lesion)

Pt will have had prior transverse colectomy for cancer (need to reimplant the IMA if stump pressure < 70 and check arteriogram pre-op)

Aneurysm will present in atypical fashion: embolization to the legs, inflammatory, aortacaval fistula, acute AAA thrombosis with pelvic and lower extremity ischemia

Pt will present later with: graft infection, aortoenteric fistula (ax-bifem 1st followed by ligation aorta), pseudoaneurysm at anastomosis

Being asked to describe your pre-op cardiac assessment (stress thallium)

There will be an intra-op anomaly: horseshoe kidney, retroaortic renal vein, left-sided IVC

Pt will be in shock and they will ask you if you want to get a CT or go straight to the OR (go to the OR and resuscitate en route!

Being asked what to do with pt with dementia, metasta- tic cancer, or elderly

Pt will have had prior abdominal surgery (colectomy →reimplant IMA!)

Being asked your feelings about “stent-grafts” (results good so far and done in symptomatic pts, but always be the conservative surgeon on the Oral Exam) Be prepared to deal with common post-op problems (pt

will likely have at least one of the following):

hypothermia acidosis coagulopathy

renal failure—(abdominal compartment syndrome, ATN, atheromatous debris, ureteral injury, hypovolemia—favorite question of the examiners is post-op AAA low UO!!!)

loss of pulses in an extremity abdominal compartment syndrome

ischemic left colon (reimplant IMA if stump pressure < 40 or Hartmann procedure post-op) post-op MI

spinal cord ischemia impotence

Strikeouts

Not knowing how to gain control of rupturing aorta Not prepping pt widely enough (include neck and

thighs . . . “chin to knees”)

Not ruling out MI or other abdominal processes Not palpating pulses

Addressing AAA first in pt with + persantine thallium or cardiac cath

Not knowing how to manage the common postopera- tive problems (see above)

Trying to perform any endovascular stent graft

Not taking asymptomatic pt with rapid AAA growth to the OR

Risk of Rupture

5 cm AAA → annual risk ~5%

7 cm AAA → annual risk ~20%