Townsend Courtney M.Jr., Evers B. Mark. Atlas of General Surgical Techniques: Expert Consult

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CHAPTER 89 • Mesenteric Ischemia 971

Mesenteric Thrombosis

◆ The proximal jejunum is usually ischemic because the stenosis involves the origin of the

SMA, and thrombectomy alone will not sufﬁ ce.

◆ The SMA is isolated as for SMA embolectomy.

◆ After systemic heparinization, the SMA is occluded and a longitudinal arteriotomy is made

in the SMA below any palpable plaque.

◆ The thrombectomy catheter is then passed proximally and distally to remove any thrombus

present. Antegrade blood ﬂ ow is usually diminished or absent, but retrograde ﬂ ow may be

quite brisk because of well-established collaterals.

◆ Arterial inﬂ ow will be required from either the supraceliac, infrarenal aorta, or iliac arteries,

which will be described subsequently.

Mesenteric Venous Thrombosis

◆ Mesenteric venous thrombosis may be primary or secondary to a number of conditions

including cancer, hypercoagulable states, polycythemia, trauma, dehydration, and pancre-

atitis. Thrombus most often involves the superior mesenteric vein (70%) and inferior

mesenteric vein (30%).

◆ At laparotomy, segmental small bowel congestion with edema of the mesentery is the usual

ﬁ nding. Segmental resection is usually the only treatment necessary. Long-term treatment

with the anticoagulant warfarin (Coumadin) to prevent further thrombotic episodes is

instituted postoperatively.

Chronic Mesenteric Ischemia

◆ Usually high-grade stenosis or occlusion of two of the three vessels (celiac artery and SMA)

supplying the viscera is necessary to cause chronic mesenteric ischemia. Evidence of large

collaterals on angiography suggests the diagnosis.

Retrograde Aortosuperior Mesenteric Bypass

◆ The SMA is exposed as described for mesenteric embolectomy, and a self-retaining

retractor is placed.

◆ A segment of the abdominal aorta that is free of signiﬁ cant atherosclerosis (as determined

on the CT scan) between the renal artery and IMA is isolated and mobilized.

◆ After systemic heparinization, the aorta is occluded between clamps, and an arteriotomy is

made on its anterior lateral aspect.

972 Section XII • Vascular

◆ A harvested segment of saphenous or superﬁ cial femoral vein or 6- or 7-mm ringed polytet-

raﬂ uoroethylene (PTFE) or Dacron graft is fashioned and anastomosed end-to-side to the

aorta with running 4-0 polypropylene suture (Figure 89-4, A). The graft is then routed in a

gentle curve to the SMA. The SMA and its branches distal to the stenosis or occlusion are

occluded with clamps and vessel loops, and a longitudinal arteriotomy is made beyond any

palpable plaque.

◆ The graft is anastomosed end-to-side to the SMA with running 5-0 or 6-0 polypropylene

suture, with care given to ﬂ ush the artery and the graft before the anastomosis is completed

(Figure 89-4, B).

◆ The entire bowel is then inspected, the mesenteric vessels are auscultated, and the anasto-

moses are assessed with color ﬂ ow Doppler ultrasound.

CHAPTER 89 • Mesenteric Ischemia 973

Superior

mesenteric artery

Aorta

Ringed

prosthetic graft

Inferior vena cava

Left renal vein

Completing

anastomosis

Atherosclerotic

lesion

Clamp

Superior

mesenteric artery

Aorta

Inferior vena cava

Left renal vein

Atherosclerotic

lesion

Ringed

prosthetic graft

FIGURE 89 –4

974 Section XII • Vascular

Antegrade Aortomesenteric Bypass

◆ When the infrarenal aorta is severely diseased, an antegrade mesenteric bypass originating

from the supraceliac aorta should be considered.

◆ After the abdomen is explored, the left lobe of the liver is mobilized by dividing the trian-

gular ligament, and the lesser sac is entered by dividing the gastrohepatic ligament.

◆ The stomach and esophagus are retracted to the left, with care given not to injure the vagus

nerves. The left lobe of the liver is retracted to the right with a self-retaining retractor

(Figure 89-5, A).

◆ The diaphragmatic crura and median arcuate ligament are then divided in the midline, and

the supraceliac aorta is mobilized for a distance of approximately 6 to 8 cm.

◆ The celiac artery and SMA are then identiﬁ ed and mobilized by dividing the autonomic

neural ﬁ bers so that a segment of each artery uninvolved with atherosclerosis is identiﬁ ed.

Heparin (100 U/kg) and mannitol (25 g) are administered.

◆ The celiac artery is then divided between clamps, and the proximal end is oversewn with

5-0 polypropylene suture (Figure 89-5, B).

◆ The aorta is occluded between clamps, and an elliptical arteriotomy is made in the aorta

(Figure 89-5, C).

CHAPTER 89 • Mesenteric Ischemia 975

Celiac trunk

Superior

mesenteric artery

FIGURE 89 –5

Aorta ready for

anastomosis

Celiac artery

Oversewn

celiac origin

976 Section XII • Vascular

◆ A 14 ⫻ 7 bifurcated prosthetic graft is fashioned and anastomosed end-to-side to the aorta

with running 3-0 Prolene suture. One limb of the graft is cut to an appropriate length,

beveled, and anastomosed end-to-end to the distal celiac artery with 5-0 polypropylene

suture (Figure 89-5, D). The vessel and graft are ﬂ ushed, the anastomosis is completed,

and ﬂ ow is reestablished.

◆ The second limb of the graft is routed behind the pancreas to the SMA. The SMA is

occluded between clamps, and a longitudinal arteriotomy is made. The graft limb is dis-

tended with blood to its optimal length and is beveled, and the anastomosis is completed

with 5-0 or 6-0 polypropylene suture (Figure 89-5, E).

Celiac anastomosis

Celiac artery

Completing superior

mesenteric artery

anastomosis

(end-to-side)

FIGURE 89 –5, cont’d

CHAPTER 89 • Mesenteric Ischemia 977

Iliomesenteric Bypass

◆ When the supraceliac and infrarenal aorta are both severely involved with atherosclerosis or

the patient is in poor general health, the common iliac artery can be used as the inﬂ ow

vessel.

◆ The peritoneum over the common iliac artery is incised, and a segment of artery is mobi-

lized, with care given not to injure the left common iliac vein.

◆ After systemic heparinization, the common iliac artery is occluded between clamps, and a

longitudinal is arteriotomy made. A limb of a bifurcated prosthetic graft including cuff of

the body or saphenous vein is fashioned and anastomosed end-to-side to the common iliac

artery with 4-0 polypropylene suture (Figure 89-6, A).

Superior

mesenteric artery

Aorta

Inferior vena cava

Left renal vein

Completing

anastomosis

Atherosclerotic

lesion

Ringed

prosthetic graft

FIGURE 89 –6

978 Section XII • Vascular

◆ The limb of the graft is routed in a gentle curve to the SMA, and the anastomosis is con-

structed end-to-side to the SMA with running 5-0 polypropylene suture (Figure 89-6, B-C).

3. CLOSING

◆ Hemostasis is secured, and the blood supply to the viscera is carefully assessed by palpation

and auscultation of the mesenteric vessels and interrogation of the anastomoses with color

ﬂ ow Doppler ultrasound.

◆ The abdomen is then closed with a looped 1-0 polydioxanone (PDS) suture.

Aorta

Superior

mesenteric artery

Completing

anastomosis

Left renal vein

Ringed

prosthetic graft

FIGURE 89 –6, cont’d

CHAPTER 89 • Mesenteric Ischemia 979

Right common

iliac artery

Inferior

vena cava

Superior

mesenteric artery

Left renal vein

Right renal vein

Ringed

prosthetic graft

Left common

iliac artery

Atherosclerotic

lesion

Aorta

FIGURE 89 –6, cont’d

980 Section XII • Vascular

STEP 4: POSTOPERATIVE CARE

◆ The patient is returned to the intensive care unit. Fluid volume, hematocrit, acid-base sta-

tus, liver function tests, and clotting factors are carefully monitored and replaced. Persistent

acidosis is usually indicative of ongoing bleeding or bowel or hepatic ischemia.

◆ Colonoscopy should be performed with care if colonic ischemia is suspected, because an

intraluminal pressure greater than 30 mm Hg may further impair colonic blood ﬂ ow.

Prompt surgery is indicated if there is persistent acidosis, ongoing bleeding, or evidence of

sepsis.

STEP 5: PEARLS AND PITFALLS

◆ Early diagnosis and treatment of mesenteric ischemia is essential if the survival rate is to be

improved.

◆ A planned second-look operation to resect marginally viable segments of bowel is an inte-

gral part of the postoperative care of patients with mesenteric ischemia.

◆ Ongoing bleeding may be due to increased ﬁ brinolysis, especially in patients undergoing

antegrade mesenteric bypass with prolonged hepatic ischemia. After other causes of bleed-

ing have been excluded, blood should be drawn for plasminogen levels, and an infusion of

small amounts of epsilon aminocaproic acid should be considered.

◆ The choice of graft material is determined by the presence or absence of fecal contamina-

tion. Prosthetic grafts are preferred because they are less likely to kink. If there is gross con-

tamination, an autogenous saphenous vein or superﬁ cial femoral vein graft should be used.

These grafts should be carefully placed to avoid kinking and recurrent ischemia.

◆ Patients undergoing surgery for mesenteric ischemia may require large volumes of ﬂ uid

intraoperatively and postoperatively and are prone to developing abdominal compartment

syndrome. If there is signiﬁ cant bowel edema, the abdomen should not be closed primarily.

Temporary abdominal content containment with plastic bags (Bogota bag) or polyglactin

mesh or application of a wound vacuum-assisted closure (VAC) device and delayed

primary closure should be done once the visceral edema has resolved.

◆ There is ongoing debate about the number of vessels to be revascularized. Patients with

acute mesenteric ischemia are usually too critically ill to withstand total revascularization,

and only the SMA should be revascularized. Revascularization of both the celiac artery and

SMA should be considered in patients with chronic mesenteric ischemia.