Endovascular Approach to Chronic Mesenteric Ischemia

Surgical Approach

Endovascular revascularization of the mesenteric ves- sels is indicated in acute or chronic clinical settings. A bypass to the celiac and/or the SMA from a supraceliac approach has the highest patency but comes with sig- ni cant morbidity and mortality. However, if the patient is at a high risk, then an endovascular approach can be initially utilized as a bridge to an open and more dura- ble procedure. The current trend is an endovascular approach rst. Open mesenteric revascularizations are being performed less, and most vascular graduates have been exposed to only a handful of cases during their training. Hence, this trend may very well have to do with the comfort level of the vascular surgeon. However, the authors believe, an initial endovascular approach for CMI serves as a bridge to open surgical therapy espe- cially if the patient is severely malnourished or very high medical risk.

For endovascular treatment of CMI, several things have to be considered: brachial versus femoral approach, type of catheter to engage the lumen, balloon expandable stent versus self-expanding, covered versus bare metal stent, and monorail versus coaxial systems.

Contraindications to Endovascular Approach

There are no absolute contraindications. Occlusions of the SMA with heavy calci cations can be a relative contraindi- cation, especially if the occlusion is up to the middle colic artery.

Celiac vs. SMA or Both

The main objective is to treat the SMA. Celiac artery stenting can be attempted if SMA angioplasty is not possible or can not be done. In a comparative analysis of celiac versus SMA angioplasty and stenting, Ahanchi

a Vert or MPA 125 are popular choices (Cook Medical, Bloomington, IN). This approach can be performed with a cut down in high-risk patients (women, small caliber arteries). Lastly, it also depends on skill set and comfort level of the surgeon. The brachial approach clearly has advantages of torquability and pushability to facilitate crossing occlusions.

Balloon-expandable Versus Self-expanding

Most interventionalists prefer a balloon-expandable stent for accurate placement. However, if an abdomi- nal procedure is planned in the future, a self-expanding stent can be used. It will keep its form and withstand retractor pressure during a subsequent open procedure, whereas the balloon-expandable stent may get crushed. Self-expanding nitinol stents are not as precise. Avoid the usage of more than one stent.

Covered Versus Bare Metal

With covered stents there are four options: Gore ViaBahn (Gore Medical, Flagstaff, AZ), Bard Fluency (Bard, Tempe, AZ), Wall Graft (Boston Scienti c, Natick, MA), and iCast (Atrium, Hudson, NH). The rst three require a large

Key Technical Steps

1. Approach via the left brachial artery. The authors recommend a cut down if the patient is at high risk for brachial complica- tions (elderly, women, small caliber arteries). A femoral approach can be used, if the angle of the SMA is not very acute.

2. Place a 6-French 90-cm sheath if approaching via the brachial artery in the descending thoracic aorta at the level of the celiac artery (a 70-cm sheath is not long enough in most instances). Imaging can be obtained from a femoral sheath simultaneously through a separate catheter.

3. The image intensi er is placed at 80–90 degrees for a lateral view and initial angiogram obtained to identify the SMA and the celiac artery. The patients upper extremities have to be out of the way (above the head) for better imaging.

4. A slightly angled, moderately stiff catheter (e.g., MPA 125) is used with a hydrophilic stiff wire such as a Road Runner or Stiff Hydrophilic Glide (Cook Medical, Bloomington, IN) for crossing an occlusion. If there is a high-grade stenosis, a more pliable wire is preferred.

5. Once the wire has crossed the lesion, exchange it with a 0.35 or 0.18 working wire. Have adequate purchase of the exchange catheter into the target artery as it may get kicked out when introducing a stiffer wire, especially from the femoral approach.

6. Advance the sheath to cross the lesion, especially an occlusion.

7. Balloon angioplasty with a 20- to 40-mm length balloon can be used to assess the extent of area to be treated and visualize the waist seen during insuf ation.

8. Once the stent is in the desired location, withdraw the sheath.

9. Deploy the stent hanging out 3–5 mm into the aorta as it is easy to miss disease at the origin. The angle of the SMA has to be factored in to have adequate coverage.

Potential Pitfalls

• The stent can sheer off the delivery catheter when going through a long heavily diseased segment. Hence, the sheath or guiding catheter should cross the lesion rst if a balloon-expandable stent is used. Similarly, predilating with a balloon can make crossing the lesion with a stent less risky. This can be dif cult if 0.18 or 0.14 wires are used, as they may not be able to provide enough support. Thus, the sheath has to cross the lesion on a 0.35 system.

• Plan on placing a single stent. Magnify the image during deployment for precision, as it can be dif cult to visualize the extent of the diseased segment and the origin of the vessel.

• The lesion may require preangioplasty for the mounted stent to go through. During this, very judicious wire control cannot be over emphasized since there is not much purchase in the SMA and wire access can easily be lost. In addition, the location of the wire must be identi ed so it is not in one of the smaller SMA branches, which can lead to a perforation. Wire movement is inevitable during the procedure, and utmost caution has to be used to keep ensuring the position of the wire.

• Dissection of the SMA is a dreaded complication. It can be avoided by minimizing wire and sheath movement with catheter exchanges. Also, avoid advancing the sheath unprotected without a dilator.

Case Conclusion

The cross table oblique arteriogram con rmed a high-grade proximal SMA stenosis and occluded celiac artery. A balloon-expandable bare metal stent (8 × 20 mm) was successfully placed in the SMA (Fig. 1).

He was then placed on nutritional supplements for the next 2 weeks.The patient gained weight while he was on supplemental nutrition and IV antibiotics. He then underwent replacement of the infected graft with femoral vein and has continued to do well postoperatively.

of vasodilator during angiography. Vasc Endovascular Surg. 2009;43(1):46-50.

CLINICAL SCENARIO CASE QUESTIONS

1. A 77-year-old woman presents with mild abdominal pain 3 weeks after colon resection for a left colon mass. She has a normal lactate but elevated WBC to 16K. Postoperatively, she has not been eating well and lost weight. After evaluation, mesenteric ischemia is sus- pected. She has an occlusion of the SMA 1.5 cm distal to the origin all the way to the middle colic on CTA. The celiac artery has a high-grade stenosis. What is the most appropriate approach:

a. Systemic heparin and open embolectomy of the SMA
b. Systemic heparin with systemic vasodilator
c. Systemic TPA
d. Angiogram via brachial approach and stent the celiac artery rst
e. Angiogram via the brachial artery approach and stent the SMA rst past the middle colic

2. Decreasing the risk of mesenteric arterial dissection with an endovascular approach is best accomplished by:

a. Using intravascular ultrasound
b. Always approaching the artery ori ce via a groin approach
c. Preprocedural clopidogrel loading
d. Care with advancing the catheter or sheath only after good wire access
e. Using self-expanding stents only