Maureen K. Sheehan
Matthew J. Sideman
Kevin E. Taubman
Presentation
A 67-year-old woman is referred for evaluation of possible chronic mesenteric ischemia (CMI). She has a 10-month history of postprandial abdominal pain, which has led to a fear of food and a 30-lb weight loss. Her past medical history is significant for hypertension, hyperlipidemia, and a 60 pack-year smoking history. She has had multiple tests including an esophagogastroduodenoscopy (EGD), colonoscopy, barium swallow, computed tomography (CT) scan, abdominal ultrasound, and a HIDA scan. She underwent a laparoscopic cholecystectomy 4 months ago for biliary dyskinesia without improvement in her symptoms.
Differential Diagnosis
The diagnosis of CMI is usually made late in the course of the disease. Most patients have had multiple tests before the diagnosis is considered. Peptic ulcer disease, biliary disease, enteritis, colitis, and gastrointestinal tumors should all be ruled out before settling on a diagnosis of CMI. However, in the patient with classic symptoms and significant risk factors, a high index of suspicion for CMI should be maintained and explored.
Patients with CMI tend to have the same risk factors as other individuals with atherosclerosis including hypertension, dyslipidemia, and smoking. The classic CMI symptom is postprandial abdominal pain, which typically occurs 15 to 45 minutes after food intake with severity frequently linearly related to the size of the meal. The pain is most often dull and located in the midepigastrium but may have some radiation. Due to the postprandial pain, many patients will develop fear of food—avoidance of food to avoid pain. As a result, significant weight loss tends to be a prevalent symptom as well. Because symptoms are general and nonspecific, patients will frequently have undergone extensive workup and perhaps treatment for their abdominal pain prior to presentation to a vascular surgeon.
Physical exam of patients with CMI tends not to be significantly telling. Patients in general will be thin secondary to their ongoing weight loss. They may have other sequelae of peripheral vascular disease, such as carotid bruits or diminished lower-extremity pulses. Patients may have an abdominal bruit present but that is neither sensitive nor specific.
Discussion
CMI is a relatively rare disease. Estimates show mesenteric atherosclerosis to affect only 17% of patients over 65 years of age, with many of the affected patients having asymptomatic disease. Open intervention was first described in 1958 followed by percutaneous intervention in 1980. Since the introduction of endovascular treatment, there has been debate regarding the best treatment for CMI. Open bypass has longer durability but carries significant morbidity and mortality. On the other hand, endovascular treatment has significantly less morbidity and mortality but also increased restenosis rates. Therefore, treatment choice needs to be individualized to the patient.
Workup
Duplex ultrasonography is an excellent screening modality for mesenteric occlusive disease. As noted previously, patients tend to have an ongoing history of weight loss and tend to be thin if not near cachectic so that imaging the celiac artery and superior mesenteric artery (SMA) with the ultrasound probe is not as difficult as usual; however, there remain the challenges of intra-abdominal gas and respiratory variation. Moneta et al. have reported that a peak systolic velocity (PSV) of 275 cm/s or greater in the SMA detects a 70% or greater stenosis with sensitivity of 92% and specificity of 96%, while a PSV of 200 cm/s or greater in the celiac artery detects a 70% or greater stenosis with a sensitivity of 87% and specificity of 80%. In a separate study, Zwolak et al. found that an end diastolic velocity (EDV) of 45 cm/s in the SMA correlated with a >50% stenosis, while the same was true of an EDV of 55 cm/s in the celiac artery. However, each vascular laboratory needs to determine their own criteria for diagnosis of mesenteric artery stenosis with validation.
Angiography is the gold standard diagnostic test and allows for definitive planning. Complete angiography requires both anteroposterior and lateral aortic views and may require selective injections of the celiac, superior mesenteric, and inferior mesenteric arteries. Atherosclerotic disease in the celiac artery and SMA tends to be orificial and may result from “spillover” disease from the aorta (Figure 1). Presence of well-developed collaterals supports the diagnosis of mesenteric ischemia. Generally, occlusion or significant stenosis of at least two of the vessels needs to be present for the patient to have symptoms; however, if the patient lacks adequate collateral pathways, symptoms may be present with disease of only one vessel.
FIGURE 1 • Aortic atherosclerotic disease with mesenteric “spillover.”
Presentation Continued
Computed tomography angiogram (CTA) of the patient showed atherosclerotic disease of the abdominal aorta with involvement of the visceral vessels. Lateral abdominal aortogram showed significant stenosis of the celiac and the SMA. Endovascular stents were place in the orifices of the celiac and SMA with resolution of abdominal pain and the patient was able to regain her weight (Figure 2).
FIGURE 2 • Celiac and SMA stenting.
Diagnosis and Treatment
CMI can be treated endovascularly with angioplasty, or more commonly, stenting of the diseased vessels. This can be done for stenosis and occlusions, assuming that the occlusions can be crossed with a wire. Endovascular treatment is attractive because it is minimally invasive, can be performed at the same time as the diagnostic angiogram, and can be done without general anesthesia. Benefits include the potential to reduce morbidity, mortality, length of hospital stays, and costs. Limitations of endovascular repair include questionable long-term durability. Restenosis within mesenteric stents is common (Figure 3).
FIGURE 3 • In-stent stenosis of an SMA stent.
Technical considerations for endovascular repair include access site and stent choice (Table 1). Femoral access can be used, but access of the mesenteric vessels can be difficult from this approach due to the angle of origin from the aorta of the celiac and SMA. A reverse curve angiographic catheter is used to access the orifice of the vessel, which can be difficult given the disease. Once the vessel is accessed, a stiff wire and either a guide or a long sheath should be advanced into the vessel to maintain access for the intervention. An easier approach is from the brachial artery, which yields a more direct access angle to the mesenteric vessels; however, sheath size needed for intervention must be taken into consideration in relation to the size of the brachial artery. If stenting is planned, a 6 Fr sheath will likely be required, which may be too large for a small brachial artery in an elderly female making brachial artery thrombosis post intervention an unacceptable risk or necessitating a brachial cutdown for sheath removal.
TABLE 1. Key Technical Steps and Potential Pitfalls to Endovascular Treatment of CMI
Once the diagnostic angiogram is completed, the decision made to intervene, and access to the target vessel accomplished, the distal vessel is assessed with angiogram and the appropriate-sized stent chosen. Intravascular ultrasound (IVUS) can be an extremely useful adjunct in choosing the appropriate-sized stent. Orificial lesions that are heavily diseased, and or calcified are best treated with balloon expandable stents given their superior radial force. If the disease extends beyond the bend in the SMA, consideration should be given to self-expanding stents to accommodate the tortuosity and motion of the artery. After successful deployment of the stent(s), a completion angiogram is performed and access surrendered. Closure devices for the access site are used at the discretion of the physician.
Success of the intervention is ultimately determined by symptomatic improvement in the patient. Function of the stents can be followed with duplex surveillance or by CT angiograms. Both modalities have their benefits and limitations. Duplex is inexpensive and noninvasive, but it is highly operator dependent and visualization of the stents can be problematic. CT is more reliable for imaging but is expensive and carries the risks of repeated radiation and contrast exposure.
Outcomes of endovascular treatment have shown good initial results but poor long-term patencies compared to open repair. Up to 30% of endovascular repairs will require secondary interventions for recurrent symptoms due to failing or failed stents. Despite these results, Medicare utilization studies have shown that mesenteric angioplasty/stenting has surpassed open surgical repair as the treatment of choice.
Surgical Repair of CMI
There are multiple options for surgical treatment of CMI (Table 2). Since the disease is most often caused by “spillover” atherosclerosis of the aorta into the origins of the celiac and the SMA, one surgical treatment is endarterectomy. To perform this operation (Table 3), a left-sided medial visceral rotation and retroperitoneal dissection is done to expose the abdominal aorta from the hiatus to the iliac bifurcation. The supraceliac aorta, infrarenal aorta, celiac, SMA, and left renal arteries are controlled with vessel loops. The patient is systemically heparinized and the vessels clamped. A “trap door” incision is made in the aorta by making transverse arteriotomies proximal to the celiac and distal to the SMA and then connecting them longitudinally on the left lateral side of the aorta. The anterior wall of the aorta with the visceral vessels is then reflected anteriorly and the atherosclerotic plaque removed from this segment as well as the celiac and SMA. The newly endarterectomized portion of the aorta is then closed primarily with running monofilament suture and flow reestablished to the bowel.
TABLE 2. Surgical Options for Treatment of CMI
TABLE 3. Key Technical Steps and Potential Pitfalls to Surgical Treatment of CMI
The other surgical option for treatment of CMI is bypass. There are multiple options and configurations for bypass of the mesenteric arteries (Table 2). One option is an antegrade bypass with the inflow arising from the supraceliac aorta. The bypass can either be to one vessel or it can be a bifurcated graft to the celiac and SMA. If only one vessel is to be revascularized, the most important vessel to bypass is the SMA as it supplies the majority of the blood flow to the gut and has collaterals to the celiac and the inferior mesenteric distributions. For this operation (Table 3), a laparotomy is performed and the supraceliac aorta exposed through the lesser sac. The crura of the diaphragm are dissected to gain full exposure of the aorta in this location. The distal targets are exposed and controlled. The celiac can be exposed through the lesser sac on the anterior surface of the aorta. The SMA needs to be exposed in the root of the mesentery. A tunnel is then created behind the pancreas connecting the exposed SMA in the root of the mesentery with the exposed supraceliac aorta. After completing the dissection, the patient is systemically heparinized and the vessels controlled. A side-biting aortic clamp can be used to partially occlude the supraceliac aorta and either a bifurcated graft or a solitary graft sewn with running monofilament suture. Autogenous venous grafts can be used instead of prosthetic if desired. The distal anastomoses are then completed in a standard fashion with running monofilament suture as well.
Another bypass option is a retrograde bypass to the mesenteric arteries (Table 2). In a retrograde bypass, the inflow is taken from either the infrarenal abdominal aorta or an iliac artery. Again, the bypass can be to a solitary mesenteric vessel or it can be bifurcated to two vessels. The operation is begun with a laparotomy and exposure of the inflow vessel with proximal and distal control (Table 3). The target vessel(s) are then exposed as described above. The patient is systemically heparinized and then the proximal and distal anastomoses are completed with running monofilament suture. Prosthetic graft material is generally used but autogenous grafts can be used as well. If vein is used for the bypass, it is preferable to make the length of the bypass as short as possible to prevent kinking of the graft. Care must be taken to measure the length and the angle to prevent this complication after the retractors have been removed and the bowel returned to its normal location. Again, if only one vessel is to be revascularized, the SMA is the most important vessel to bypass. A prosthetic graft has a theoretic advantage in this scenario. An externally reenforced polytetrafluoroethylene graft can be used in a gentle reverse “C” configuration from the infrarenal aorta (or iliac) to the SMA. The gentle curve allows the graft to lie within the bowel without kinking.
Regardless of the surgical approach to mesenteric revascularization, all patients need to be carefully monitored postoperatively for signs of visceral ischemia. Large-volume resuscitation may be necessary, especially if patients have sustained prolong bowel ischemia times. Lactate levels, urine output, and volume status all need to be closely monitored. The intensive care unit (ICU) setting is typically best suited for the initial postoperative care.
Case Conclusion
Approximately 1 year after stenting of the celiac and SMA, the patient experienced recurrent symptoms of postprandial abdominal pain, fear of food, and weight loss. She continued to smoke heavily. CTA showed near occlusion of both stents (Figures 4 and 5). Conversion to surgical bypass was recommended. She underwent antegrade aortoceliac and aorto-SMA bypass without sequelae. She recovered well and had complete resolution of her symptoms. Postoperative CT scan showed good function of her bypass grafts (Figure 6).
FIGURE 4 • Stenosis of celiac stent
FIGURE 5 • In-stent stenosis of SMA stent.
FIGURE 6 • Antegrade aortoceliac and aortomesenteric bypass.
TAKE HOME POINTS
· CMI is a rare disease.
· The triad of postprandial pain, fear of food, and weight loss must be present to entertain the diagnosis.
· Atherosclerotic disease with “spill-over” into the visceral vessel orifices is the main cause.
· Lateral aortogram is the gold standard test.
· Open surgical treatments include endarterectomy, antegrade bypass, and retrograde bypass.
· The SMA is the most crucial artery to revascularize.
· Endovascular treatment caries lower morbidity but also has lower long-term patency rates.
SUGGESTED READINGS
Ernst CB. Bypass procedures for chronic mesenteric ischemia. In: Ernst CB, Stanley JC, eds. Current Therapy in Vascular Surgery. 4th ed. Mosby, St. Louis, MO, 2001:682–685.
Moneta GL, Yeager RA, Dalman R, et al. Duplex ultrasound criteria for diagnosis of splanchnic artery stenosis or occlusion. J Vasc Surg. 1991;14(4):511–518.
Oderich GS. Current concepts in the management of chronic mesenteric ischemia. Curr Treat Options Cardiovasc Med. 2010;12(2):117–130.
Oderich GS, Malgor RD, Ricotta JJ II. Open and endovascular revascularization for chronic mesenteric ischemia: tabular review of the literature. Ann Vasc Surg. 2009;23(5):700–712.
Schermerhorn ML, Giles KA, Hamdan AD, et al. Mesenteric revascularization: management and outcomes in the United States, 1988–2006. J Vasc Surg. 2009;50(2):341–348.
Zwolak RM, Fillinger MF, Walsh DB, et al. Mesenteric and celiac duplex scanning: a validation study. J Vasc Surg. 1998;27(6):1078–1087.