Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

An ACT is drawn and additional heparin is administered to ensure adequate heparinization (ACT >250). The SMA and its jejunal branches are occluded, and a transverse arteriotomy is made (Figure 89-3, A).

A balloon catheter is then passed proximally toward the origin of the SMA, the embolus is extracted, and the proximal SMA is occluded once adequate inflow has been restored (Figure 89-3, B). The balloon catheter is also passed distally to ensure no thrombotic material remains (Figure 89-3, C). The clamps are temporarily removed, and the vessel is flushed proximally and distally.

Transverse arteriotomy in superior mesenteric artery

A

Embolus

Catheter removing embolus from proximal superior mesenteric artery

B

Catheter removing embolus from distal superior mesenteric artery

C

FIGURE 89–3

9 7 0 S E C T I O N X I I • VA S C U L A R

The lumen of the SMA is irrigated with heparinized saline, and the arteriotomy is approximated with interrupted 6-0 polypropylene suture (Figure 89-3, D).

The bowel is inspected, and mesenteric vessels are interrogated with Doppler ultrasound to ensure adequate perfusion. Nonviable segments of bowel should be resected.

Interrupted sutures to close arteriotomy

D

FIGURE 89–3, cont’d

Mesenteric Thrombosis

The proximal jejunum is usually ischemic because the stenosis involves the origin of the SMA, and thrombectomy alone will not suffice.

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 flow is usually diminished or absent, but retrograde flow may be quite brisk because of well-established collaterals.

Arterial inflow 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 pancreatitis. 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 finding. 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 significant 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.

9 7 2 S E C T I O N X I I • VA S C U L A R

A harvested segment of saphenous or superficial femoral vein or 6- or 7-mm ringed polytetrafluoroethylene (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 flush 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 anastomoses are assessed with color flow Doppler ultrasound.

9 7 4 S E C T I O N X I I • VA S C U L A R

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 triangular 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 identified and mobilized by dividing the autonomic neural fibers so that a segment of each artery uninvolved with atherosclerosis is identified. 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).

Celiac trunk

Superior mesenteric artery

A

Oversewn celiac origin

Celiac artery

B

Aorta ready for anastomosis

Celiac artery

C

FIGURE 89–5

9 7 6 S E C T I O N X I I • VA S C U L A R

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 flushed, the anastomosis is completed, and flow 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 distended 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

D

Completing superior mesenteric artery anastomosis (end-to-side)

E

FIGURE 89–5, cont’d

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 inflow vessel.

The peritoneum over the common iliac artery is incised, and a segment of artery is mobilized, 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).

Aorta

Ringed prosthetic graft

Superior mesenteric artery

Completing anastomosis

A

FIGURE 89–6

9 7 8 S E C T I O N X I I • VA S C U L A R

The limb of the graft is routed in a gentle curve to the SMA, and the anastomosis is constructed 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 flow Doppler ultrasound.

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

Left renal vein

Ringed prosthetic graft

Completing anastomosis

Superior mesenteric artery

Aorta

B

FIGURE 89–6, cont’d