Isolated dissection of the superior mesenteric artery without involvement of the aorta is rare.1 In the past, treatment methods were mainly aimed at by-pass surgery and arterial neoplasty as well as medical therapy. Recently, we have done endovascular stenting in two cases who suffered from spontaneous isolated superior mesenteric artery dissection, and achieved satisfactory results. Our approach may help to establish a new way to treat this kind of disease.
Seventeen days before hospitalization, the patient (male, 43 years old). suffered from superior abdominal pain after breakfast. The pain seemed to be intermittent at first, then turned into continuous, lancinating severe pain accompanied with vomiting, which were mainly gastric contents rather than hematodes ones. The symptom could be relieved a bit after vomiting. The second day post the occurrence of the symptom, the abdominal pain was aggravated together with severe vomiting of dark brown liquid. The symptoms were also accompanied by vertigo and temple unconsciousness (lasting for 3 minutes to 4 minutes) with a blood pressure of 90/40 mmHg. After emergency treatment with a transfusion, the symptoms were relieved but still superior belly vague pain and abdominal distention remained after dinner. As a result, the patient had to come to our hospital. Since the occurrence of the disease, no dark stools or diarrhea existed. The patient never had major trauma or surgical history.
During the hospitalization, physical examination had detected the following signs: well-stacked belly, no gastrointestinal form or peristaltic rushes. A tender solid mass of approximately 15 cm × 8 cm without clear boundary was palpable in the superior belly, which had a rough surface, fixed location and no vascular murmur. Both the blood routine test and biochemical test were normal.
On reconstituted 3-dimensional CT (GE Lightspeed VCT American) and colored Doppler (PHILIPS HD11, Holland) scan, isolated dissection of the superior mesenteric artery could be detected with thrombus formation in false lumen, and hematoma could be found in minor omental bursa (Figure 1 A and B). The dissection occurred at about 1.5 cm from the origin of the superior mesenteric artery and the true lumen was compressed on Digital Subtraction Angiography (DSA) (GE LCV+) (Figure 1C). Then, we put an 8F guiding catheter to the entrance of the dissection part of superior mesenteric artery and implanted a Wallstent RP stent with a size of 8 mm in diameter and 28 mm in length inside of the artery.
After stent implantation, the patient's angiography suggested that the arterial lumen had satisfactory shape and the shadow of the false lumen thinned a lot compared to previous image and inferior pancreaticoduodenal artery as well as jejunal arteries had favorable angiographic image (Figure 1D). In the clinical follow up 6 months after the intervention on Doppler (PHILIPS HD11) image, the superior mesenteric artery kept open well with thrombus formation in the previous false lumen. The patient never suffered from symptoms such as abdominal pain post the intervention (Figure 1E).
Two months before hospitalization, the patient (female, 54 years old). began to suffer from distension of the head when she felt nervous. This symptom was not accompanied by vertigo, headache, nausea or vomiting. At the same time, her blood pressure was 140/100 mmHg, which was relieved after taking some antihypertensive agent. When she came to our hospital, there was no obvious abdominal pain or vertigo, diarrhea and bloody stools.
The biochemical tests were all right including kalium, calcium tests, blood routine test, hepatic function and blood fat calculation.
The dissection of the superior mesenteric artery was detected by chance on superarenal gland CT (GE Lightspeed VCT) scan. The CT showed that the wall turned was thickened at the origin of the superior mesenteric artery and the diameter of the distal part of the artery was enlarged with an intimal flap that divided the vessel into true and false lumen (Figure 2 A and B). On DSA (GE LCV+), there was dissection formation locating in the place 2.5 mm away from the origin of the superior mesenteric artery and the associated artery had midrange stenosis (Figure 2C). The diameter of the proximal part of the main vessel of the superior mesenteric artery was 6 mm on the angiography. Then, we put a RH catheter to the distal part of the superior mesenteric artery and inserted a stiff guidewire with a length of 260 cm along the catheter. After that, the guide wire was kept in place, and the RH catheter was replaced with a 10F guiding catheter. Finally a FLUENCY™ covered stent with a size of 8 mm in diameter and 40 mm in length was placed in the true lumen at the level of the dissection.
The patient's angiogram after the intervention showed a widely patent true lumen with improved flow in the distal branches of the superior mesenteric artery, and the false lumen could not be seen (Figure 2D). On follow up 2 months after the intervention by contrast-enhanced CT (GE Lightspeed VCT), there were full patency of the grafts and distal end of superior mesenteric artery (Figures 2E-2H). The patient also had no symptoms post the interventional therapy.
The etiological factor of spontaneous isolated superior mesenteric artery dissection is still unclear. Some researchers propose that its occurrence is related to paratherapeutic injury, tunica media pathological changes accompanied by Marfan's syndrome, atherosclerosis, fibromuscular dysplasia, arteritis, infection and trauma.1 There have been only 56 cases reported since Bauersfeld2 described this disease for the first time as spontaneous isolated superior mesenteric artery dissection in 1947. Another data with 6666 autopsy cases suggested that the incidence for spontaneous isolated superior mesenteric artery dissection was 0.06%,3 which was mainly occurred on the place that was 1 cm-6 cm away from the origin of the superior mesenteric artery.4
There was gender difference in the distribution of this disease, mainly affecting males.4 This disease had no significant clinical symptoms in early stage. The main symptoms and signs in the mid and late stage are as follows: First, indefinite abdominal pains due to intestinal ischemia. Second, rupture of the dissection resulted in hemorrhagic shock. It seldom has objective findings on clinical routine examination but signs of vascular murmur may be detected.5 The mortality of the disease had reached as high as 100% in the past, which were mainly due to embolism or rupture of the superior mesenteric artery. Due to the development of modern diagnostic and treating methods, the death rate of such disease decreased nearly to 0.4
Enhancement CT scan is the major way to diagnose the spontaneous isolated superior mesenteric artery dissection,6 which could be performed in the patients who get agnogenic abdominal pain.7 The significant appearances of the disease in the early stage on CT scan are mainly showed as thrombus formation in the false lumen, intramural hematoma and valve formation in the vascular lumen, and increased attenuation of the fat around the superior mesenteric artery. The increased attenuation of the fat may be the key to diagnosis during the early stage. In late stage, the films mainly show enlargement of the caliber of superior mesenteric artery, hematoma of the mesentery and hemorrhagic ascites.8
Treatments for this disease vary according to the clinical situation of the patients. First, patients who had hypovolemic shock or peritonitis needed surgical treatment. Second, patients who suffered from dissection without abdominal pain could be treated with conservative drug therapy. Third, we could apply endovascular therapy on patients with only abdominal pain but had satisfactory distal out-flow.9 There are different ways for surgical treatment:9 Affected vessel excision together with graft transplantation, autogenic superior mesenteric artery transplantation, endarterectomy, gastroepiploic artery by pass surgery and open surgery for thrombectomy. Sparks et al5 suggested that the indications for surgical treatment of this disease in the early stage are as follows: first, the arterial lumen enlarge like aneurysm; second, occlusion of the true lumen and anticoagulant therapy does not work. Getting into the lesion and remolding of the vascular lumen are both tough problems for surgical treatment. Nonsurgical methods include using warfarin to prevent thrombus formation or distal embolism.
Interventional therapy was mainly applied on patients with patent out flow. Leung et al10 reported for the first time in 2000 of using Wallstent stent to treat a spontaneous isolated superior mesenteric artery dissection. They also emphasized that early diagnosis and thrombolysis could prevent necrosis of the intestine. Yamakado et al11 reported that using Z stent to treat abdominal dissection could cause embolism of superior mesenteric artery. He supposed that the stiff edge of the Z shape stent might tear the intima of the artery. As a result, flexible self-expandable stent might be a better choice. For one of the cases reported by Yamakado, using bare metal stent to cover the entrance of dissection achieved satisfactory results. However, there was contrast leaking into the false lumen on angiography. In order to prevent the contrast from leaking, we applied covered stent to treat the spontaneous isolated superior mesenteric artery dissection for the first time in the second case and found that covered stent could prevent internal leaking better than the bare metal stent and could achieve better results in angioplasty and blockage of the orificium fistulae of the dissection. There was no reference in the literature citing the use of covered stent to treat spontaneous isolated superior mesenteric artery dissection both at home and abroad. However, we should pay attention to the precise of the length of the stent to prevent the side branch of jejunal arteries from blockage when using covered stent to treat spontaneous isolated superior mesenteric artery dissection. Froment et al12 and Leung et al10 had used Wallstent stent with length of 70 mm and 68 mm respectively with no significant complication. There was also no complication in the two cases.
Complications caused by interventional therapy mainly include distal embolism,13 and temporary hypotension, which could be due to lack of increased blood flow after dilatation or vasodilator substance released caused by ischemia-reperfusion reaction.14 It is rare to find in-stent restenosis or side branch arterial occlusion.
In conclusion, using interventional therapy to treat spontaneous isolated superior mesenteric artery dissection could achieve an immediate and satisfactory result. However, the long term curative effects need to be observed.
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