This article is part of the operation script for grafting an abdominal aortic aneurysm. The article can be used on its own, or to go to the next part of the operation, click on NEXT PART OF THE OPERATION at the bottom of this page.

AORTIC ANEURYSM 220 SECTION 10.00 - CONTROLLING THE LOWER END OF THE ANEURYSM

STEP 10.01 INTRODUCTION

This dissection is usually easier than for the upper end of the aneurysm.

There is less urgency for speed now that the pressure in the leaking aneurysm has been controlled.

The main hazard is avoiding damage to the iliac veins.

STEP 10.02 DISPLAY THE POSTERIOR PERITONEUM

This is the peritoneum lying below the fourth part of the duodenum, with the descending colon on the left and the small bowel on the right.

This may be the site of an enormous haematoma and infiltration from blood from a leaking aneurysm.

STEP 10.03 OPEN THE POSTERIOR PERITONEUM

Use dissecting scissors and a pledget on a stick.

Start at the site of opening the peritoneum at the lower border of the duodenum.

Make a longitudinal cut into the peritoneum from the upper end of the aneurysm to the common iliac arteries.

Run the dissection down the mid line of the aorta.

Finish at the bifurcation of the aorta.

This cut may run to one side or another.

The origin of the iliac arteries may be hidden by the aneurysm or displaced by the tortuosity of the arteries themselves.

Avoid the ureters, which run over the iliac arteries to the pelvis.

The ureters lie behind the gonadal veins.

The blue of these veins is a guide to the ureters

The ureters are pale, with longitudinal vessels.

They show peristalsis when squeezed gently with forceps.

They will usually be swept laterally, under the lateral leaf of peritoneum.

They will eventually lie lateral to an aorto-aortic graft.

They should usually be placed posterior to the limbs of an aorto - bifemoral graft.

STEP 10.04 DIVIDE THE INFERIOR MESENTERIC VEIN

This will improve exposure of the aorta and prevent inadvertent damage to the vein.

The vein runs behind the posterior peritoneum on the left, usually on medial to inferior mesenteric artery.

It runs cephalically, lateral to the duodeno – jejunal flexure.

The blood drainage of the large bowel will reroute along other mesenteric veins.

Tie off the vein using eg 2/0 Vicryl. (Ethicon W9136)

STEP 10. 05 RETRACT THE PELVIC STRUCTURES

Use a Deaver retractor in the lower part of the wound

Display the lower aorta and pelvic cavity.

STEP 10.06 LOOK FOR ILIAC ANEURYSMS AND STENOSES

Both aneurysms and stenoses will need to be bypassed by a Y graft.

Only aneurysms need to be isolated as well as bypassed.

For a leaking iliac aneurysm:

Plan to isolate the aneurysms once the lower end of the aorta and the lumbar arteries have been controlled.

STEP 10.07 TECHNIQUE FOR ISOLATING DISTAL ANEURYSMS

Ideally the vessel feeding blood to the aneurysm and the vessel draining blood from the aneurysm, should be ligated.

This is not always possible due to:

The site of the aneurysm.

The direction of blood flow to aneurysm after a Y graft.

Excision of an aneurysm may be justified only in a femoral artery but not in an iliac artery.

Dissect the relevant vessel off the associated vein.

Use O’Shaughnessy forcep as for the aorta.

Pass a double 2/0 Vicryl tie around the artery.

Hold the ends in an artery forcep.

Do not tie them off until the graft has been inserted.

STEP 10.08 ISOLATION OF AN ANEURYSM OF ONE COMMON ILIAC ARTERY

Plan to tie off the affected common iliac artery above and below the aneurysm.

Blood supply to the pelvic organs will come via the limb of the graft on the same side, and retrogradely up the external and internal iliac arteries.

STEP 10.09 ISOLATION OF BILATERAL COMMON ILIAC ANEURYSMS

Plan to tie off both common iliac arteries above and below the iliac aneurysms.

Blood supply to the pelvic organs will come via the limbs of the graft on the each side, and retrogradely up the external and internal iliac arteries.

STEP 10.10 ISOLATION OF A UNILATERAL EXTERNAL ILIAC ARTERY ANEURYSM

Plan to tie off the external iliac artery above and below the aneurysm.

Blood supply to the pelvic organs will come via the limbs of the graft on the opposite side, and retrogradely up the external iliac arteries.

STEP 10.11 ISOLATION OF BILATERAL EXTERNAL ILIAC ARTERY ANEURYSMS

Plan to tie off the external iliac artery above and below the larger of the two aneurysms.

Blood supply to the pelvic organs will come via the limb of the graft on the opposite side, and retrogradely up the smaller aneurysm and the internal iliac artery.

The smaller aneurysm should expand more slowly in the future.

STEP 10.12 ISOLATION OF UNILATERAL INTERNAL ILIAC ARTERY ANEURYSM

Plan to tie off the internal iliac artery proximal to the aneurysm.

Blood supply to the pelvic organs will come via the limb of the graft on the opposite side, and retrogradely up the opposite internal iliac artery.

STEP 10.13 ISOLATION OF BILATERAL INTERNAL ILIAC ARTERY ANEURYSMS

Plan to tie off the internal iliac artery proximal to the larger aneurysm.

Blood supply to the pelvic organs will come via the limb of the graft on the opposite side, and retrogradely up the opposite external iliac artery and through the internal iliac aneurysm.

The smaller aneurysm should expand more slowly in the future.

STEP 10.14 ISOLATION OF A UNILATERAL FEMORAL ANEURYSM

Plan to anastomose the limb of the Y graft to a non –aneurysmal section of the superficial femoral artery distal to the aneurysm.

Tie off the femoral artery above and below the aneurysm.

Blood supply to the thigh muscles should be adequate via anastomotic channels from the superficial femoral artery.

Blood supply to the pelvic organs will come via the limb of the graft on the opposite side, and retrogradely up the opposite external and internal iliac arteries.

STEP 10.15 ISOLATION OF BILATERAL FEMORAL ANEURYSMS

Plan to anastomose the limbs of the Y graft to non – aneurysmal sections of the superficial femoral arteries distal to the aneurysm.

Tie off the femoral artery above and below the larger of the aneurysms. Excision is often possible.

Blood supply to the thigh muscles should be adequate via anastomotic channels from the superficial femoral arteries.

Blood supply to the pelvic organs will come via the limb of the graft on the opposite side, and retrogradely up the femoral aneurysm and the external and internal iliac arteries.

The smaller aneurysm should expand more slowly in the future.

Consider an extra graft from one limb of the Y graft to an iliac artery.

STEP 10.16 ISOLATION OF POPLITEAL ARTERY ANEURYSMS

Surgery on popliteal artery aneurysms can be postponed to a later date.

STEP 10.17 COMBINATIONS OF ANEURYSMS

Follow the above principles to create procedures that will ensure satisfactory blood flow to the pelvis and the lower limbs.

STEP 10.18 DIVIDE THE INFERIOR MESENTERIC ARTERY

Look out for the inferior mesenteric artery running downwards on the left side of the posterior peritoneum.

If you cannot find it:

It may be thrombosed.

Make sure that you have identified the left ureter first.

Dissect out the mesenteric artery, double ligate it with eg 2/0 Vicryl (Ethicon W9125) and divide it.

The left colon and upper rectum should obtain sufficient blood supply from anastomoses with the marginal artery and pelvic vessels.

If you cannot find the artery:

Continue with the dissection.

Be prepared to stitch the artery off from inside the aorta after opening the sac, if it has not thrombosed.

STEP 10.19 DISSECT OUT THE ORIGIN OF THE LEFT COMMON ILIAC ARTERY

Use O’Shaughnessy forceps or a mixture of finger and blunt dissection.

The common, the external and internal iliac arteries may be displaced from their usual positions and directions.

This can be caused by the aneurysm and/or a large haematoma.

Also, any dilatation of the iliacs is usually associated with lengthening and tortuosity of the vessels.

Make sure you have dissected the common iliac arteries, and not the others.

If the iliac veins are adherent to the arteries,

Only display the front and the sides of the iliac arteries ready for a right angled De Bakey clamp to occlude the vein as well as the artery later.

• • • This method is preferred by many surgeons instead of attempting a potentially hazardous complete dissection of the arteries.

Control abnormal branches of the iliac arteries with sloops, double wrapped around and clipped with artery forceps.

If the iliac veins bleed:

Control them with 5 minutes of pressure.

If this fails:

Repair the defects with eg 4/0 Prolene (Ethicon W8935) .

If this fails:

Tie the veins off using 2/0 Vicryl (W9025).

STEP 10.20 DISSECT OUT THE ORIGIN OF THE RIGHT COMMON ILIAC ARTERY

As for the left common iliac artery (STEP 10.19).

STEP 10.21 DISSECT OUT THE ORIGIN OF THE LEFT EXTERNAL ILIAC ARTERY

As for the left common iliac artery (STEP 10.19).

STEP 10.22 IDENTIFY THE ORIGIN OF THE RIGHT EXTERNAL ILIAC ARTERY

As for the left common iliac artery (STEP 10.19).

STEP 10.23 CLAMP THE LEFT COMMON ILIAC ARTERY

Use a right angled De Bakey clamp (3 clicks).

Arrange the handles to lie down towards the thigh so as to be out of the way of the anastomoses.

If the vessel is too deep:

Use a straight De Bakey clamp.

Beware of knocking the clamp during the anastomosis.

STEP 10.24 LOCALLY ANTICOAGULATE THE DISTAL LEFT ILIAC ARTERY

Use 120 ml. of Heparinised Saline, a 20 ml. syringe and a green topped 21 SWG needle.

Check the needle is pressed onto the syringe until it has stopped creaking.

Angle the needle on the syringe to 30 degrees to avoid passing the needle through the back wall of the artery.

Squeeze the artery distal to the clamp to find an uncalcified area of wall.

This squeezing will also help detect whether the artery is thrombosed.

Push the needle into the anterior wall at 30 degrees to the vessel.

Avoid pushing the needle through the posterior wall.

Aspirate blood into the syringe before injecting, to confirm you are in the lumen of the artery.

If bubbles aspirate:

You have gone through the back wall.

Reposition the needle.

If blood does not aspirate:

You may have gone through the posterior wall.

Reposition the needle.

If blood still does not aspirate:

The artery may contain blood clot, aneurysmal debris or be blocked by atheroma.

Your initial clinical examination of the patient should have suggested any arterial blockage).

Continue with the operation, but be prepared to perform an embolectomy or to eventually use a straight graft.

If saline fills the wound:

You have gone through the back wall of the artery.

Reposition the needle.

STEP 10.25 CLAMP THE RIGHT COMMON ILIAC ARTERY

As for the left common iliac artery (STEP 10.19).

STEP 10.26 LOCALLY ANTICOAGULATE THE DISTAL RIGHT ILIAC ARTERY

As for the left common iliac artery (STEP 10.19).

You have now stopped flow of blood into the aneurysm from above and from below.

The next step is to stop blood flow into the back of the aneurysm from the lumbar arteries.

The aneurysm has to be opened to do this.

NEXT PART OF THE OPERATION

LAST PART OF THE OPERATION

BACK TO START OF THE OPERATION