Vascular Control III Pig Lab.docDocument Transcript
SIU School of Medicine
Vascular Control III
By the end of this laboratory session participants should be able to…
1) Expose the infra-renal abdominal aorta and common iliac arteries.
2) Perform a tube graft replacement of the infra-renal aorta, analagous to the
repair of an infra-renal abdominal aortic aneurysm in human subjects.
The anatomy of the abdominal aorta and iliac vessels should be reviewed. In
addition, prior to participation in the animal laboratory, the basic techniques of
vascular control and the creation of an end-to-end vascular anastomosis should be
practiced in the surgical skills lab using laboratory models.
III. SUGGESTED READING
1) Zollinger & Zollinger. Atlas of Surgical Operations 7th Edition. McGraw Hill
Inc., New York, 1993.
Anatomy of the Abdominal Aorta and IVC - Plate IV
Resection of Abdominal Aortic Aneurysm - Plate CXXXV-VIII
2) Sabiston DC. Textbook of Surgery 15th Edition. W.B. Saunders Co.,
Aortic Abdominal Aneurysms
IV. ANATOMICAL CONSIDERATION
There are several anatomic structures that the surgeon needs to be aware of during
repair of an infra-renal abdominal aortic aneurysm.
The 3rd and 4th portions of the duodenum are retroperitoneal structures
overlying the abdominal aorta. The duodenum must be carefully
mobilized to the right in order to expose the aortic neck
2) Mesenteric Lymphatic’s
As the aorta is cleared of overlying tissue, major mesenteric lymphatic’s
joining the cisterna chyli must be ligated prior to division in order to avoid
a lymphatic leak.
3) Inferior Mesenteric Vein (IMV)
The IMV crosses from left to right over the upper aspect of the infra-renal
aorta. To gain adequate exposure, it may need to be divided. Care should
be taken to avoid excessive traction on the small bowel that is retracted
superiorly in order to prevent tearing of this vein.
4) Left Renal Vein
The left renal vein crosses the aorta anteriorly en route to the inferior vena
cava (IVC) at the level of the aortic neck. The vein needs to be identified
and dissected in order to achieve cephalad retraction (Figure 2). If
additional exposure is required, the vein may be divided medially so that
the venous flow from the left kidney can be diverted retrograde through
the left adrenal, gonadal, and descending lumbar tributaries (Figure 3).
The location of the left renal vein should be noted if preoperative CT scan
is performed since the vein may occasionally lie posterior to the aorta. A
small or absent left renal vein anterior to the aorta may be the only clue (if
preoperative CT scan is not performed) that a retrograde left renal vein
exists which if unrecognized, may lead to major venous injury during
attempts at circumferential proximal aortic control.
5) Sympathetic Nerves
Sympathetic fibers cross over the anterior surface of the aorta,
communicating with lumbar ganglia laterally and then continuing across
the origin of the left common iliac artery (CIA) and downward to join the
pelvic plexuses (Figure 4). These nerves affect sexual function and
division should be avoided, if possible.
6) Common Iliac Veins
The iliac veins are a source of major bleeding that may be quite difficult to
control. The proximal right CIA lies directly on top of the left iliac vein
just beyond the aortic bifurcation. This is a notorious site for major
iatrogenic venous injury since the vein is adherent to the artery and may
be torn during attempts at CIA circumferential control.
The Ureter may be seen as it passes anterior to the iliac vessels (Figure 5).
In addition, it may be adherent to the surface of large aneurysms
8) Lumbar Veins
Lumbar veins, lying posterior to the aorta, may be the source of
troublesome bleeding if complete division of the aortic neck is performed.
Therefore, the posterior wall of the aortic neck is left intact.
9) Inferior Mesenteric Artery (IMA)
Dissection of the tissue overlying the aorta should be performed to the
right of the origin of the IMA so that it is not inadvertently injured
V. DESCRIPTION OF THE LABORATORY MODULE
A review of the technical aspects of the procedure will be presented and any
general questions will be answered. Two participants will be assigned to each
pig. The pigs will be sedated, anesthetized, and monitored by the DLAM Surgery
Suite staff. The participants will work together to perform a midline laparotomy,
achieve aortoiliac exposure, and place a PTFE interposition graft from the infra-
renal aorta to the aortic bifurcation. Closure of the retro peritoneum and
laparotomy incision will complete the session.
VI. DESCRIPTION OF THE PROCEDURE
1) The abdomen is opened through a long midline incision extending from the
xiphoid to the pubis (Figure 6).
2) After a thorough abdominal exploration, the duodenum and small bowel are
mobilized to the right by incising the peritoneal attachments to the left of the
duodenum (Figure 1).
3) The duodenum and small bowel are placed behind a large pad and retracted to
the right. Next, the tissue overlying the aorta is incised from the level of the
left renal vein to the aortic bifurcation, clipping or ligating any traversing
lymphatics and small vessels.
4) The left renal vein is mobilized to allow for upward retraction (Figure 2). If
necessary for adequate exposure, the renal vein may be divided (Figure 3).
5) The surface of the aorta is cleared of tissue, keeping to the right of the inferior
mesenteric artery in case reimplantation of the vessel is necessary. The IMA
is controlled with a double vessel loop (Figure 4, 5).
6) The aortic neck just below the renal arteries is then dissected laterally and
blunt finger dissection is used to encircle the aorta. Using an angled vascular
clamp, umbilical tape is passed posteriorly to aid in aortic vascular control and
cross-clamping (Figure 7). Alternatively, a red rubber catheter, cut across its
tip, may be passed initially and then used to guide the vascular clamp around
the aorta (Figure 8)
7) The proximal common iliac arteries are dissected anteriorly and laterally. Red
vessel loops are passed around each vessel twice using a right angle clamp.
8) The subject is given a heparin bolus (100 units/kg in human patient).
9) Using aortic sizers, the proximal aortic neck is measured and an appropriate
graft is chosen.
10) Both common iliac arteries are clamped using angled DeBakey clamps
11) The aorta is clamped just below the renal arteries using a Satinsky clamp or a
12) The aorta is opened longitudinally, using a #11 blade and then the Potts
scissors, “T’ing off” the aortotomy proximally and distally (Figure 10). In the
human patient with an aneurysm, the thrombus is removed (Figure 11).
13) Bleeding lumbar vessel is ligated from the interior of the aorta using silk
sutures in a figure-of-8 fashion (Figures 12, 13).
14) A vigorously back-bleeding IMA may be over sewn using Silk suture placed
from within the aneurysm sac to avoid occluding the proximal IMA branches.
Sometimes the IMA may need to be reimplanted.
15) The proximal anastomosis is performed using Prolene suture (3.0 Prolene in
human subjects) in an end-to-end fashion, beginning posteriorly. The deep
posterior bites incorporate a double thickness of aortic wall with each pass.
The sutures are run in an over-and-over fashion on each side, ending in the
midline anteriorly (Figures 14, 15, 16). Sutures are placed from the interior to
the exterior of the vessel to avoid pushing the edge of plaque inward, creating
an internal flap or dissection (Figure 17).
16) A vascular clamp is placed on the distal tube graft and the proximal aortic
clamp is momentarily released to check for proximal anastomotic bleeding.
Bleeding sites may be over sewn using additional Prolene suture. Once
hemostasis at the proximal anastomosis is achieved, the aortic clamp is
17) The tube graft is then transected distally at the appropriate length to perform a
tension-free, kink-free interposition graft (Figure 18).
18) The distal aortic anastomosis is performed as described for the proximal
anastomosis. Prior to completing the final few anterior sutures, the common
iliac arteries and the graft are flushed to remove any air or debris by briefly
loosening each of the vascular clamps. The sutures are then tied.
19) The vascular clamp on the graft is released to check for anastomotic bleeding.
Hemostasis is achieved as described for the proximal anastomosis.
20) One common iliac artery clamp is removed, allowing for blood pressure
stabilization after flow is restored to one leg. Until the patient’s blood
pressure is in an acceptable range, partial unclamping may be necessary.
Once stabilized, the other common iliac artery clamp is removed. The
femoral pulses and pedal pulses are checked at this time to be sure distal
embolization of atherosclerotic plaque has not occurred.
21) Irrigation may be performed and hemostasis inspected again.
22) The bowel is also checked for viability (IMA ligation or reimplantation).
23) In the case of a human patient, the aneurysm sac is closed around the graft
using vicryl suture (Figure 19).
24) Using vicryl suture, the retro peritoneum is closed.
25) The midline fascia and skin are then closed.
Self-retaining ring system
Red vessel loops – maxi & mini
PTFE graft – 6 x 40 or 8 mm x 40
Suction – Fraser and Yankauer tips
1. Ouriel, K. and Rutherford R. Atlas of Vascular Surgery: Operative
Procedures. W.B. Saunders Company, New York 1998.
2. Rutherford R. Atlas of Vascular Surgery: Basic Techniques and Exposures.
W.B. Saunders Company, Philadelphia 1993.
3. Zollinger & Zollinger. Atlas of Surgical Operations 7th Edition. McGraw Hill
Inc., New York, 1993.