Superior mesenteric artery aneurysms: is presence an indication for intervention?
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INTRODUCTION: Although rare, superior mesenteric artery (SMA) aneurysms have a definite rupture risk. Past reports have suggested that this risk is low, yet most investigators recommend repair in selected patients. We reviewed our experience with 21 patients to try to determine when intervention was indicated. METHODS: A retrospective review of the medical records of all patients with SMA aneurysms at our institutions from January 1980 through December 1998 was undertaken. Only patients with true aneurysms of the SMA were included. RESULTS: Twenty-one patients with true SMA aneurysms were identified and included 14 males (67%) and seven females (33%). This represents a 6.9% incidence rate of all visceral aneurysms seen at our institutions. Eight patients (38%) had rupture at presentation, including seven of the 14 males (50%). In contrast to previous reports, only one patient (4.7%) had an infectious etiology. Five patients were on beta-blocker therapy, but none were seen with rupture. However, eight of the remaining 16 patients (50%) without beta-blockade had rupture. Thirteen patients (62%) had calcified aneurysms, but all ruptures were seen in noncalcified aneurysms. Operative intervention occurred in 11 of the 21 patients (52%). All eight patients with rupture underwent operation, including six ligations and one successful embolization, and one patient died before completion of repair. The operative mortality rate was 37.5% for ruptured aneurysms. Elective repair included one prosthetic graft, one excision and patch angioplasty, and one embolization, with no mortality. Ten of the 21 patients (48%) with SMA aneurysms were observed, and all were alive and well at a mean of 67 months' follow-up (range, 2 to 148 months). CONCLUSION: SMA aneurysms are rare but appear to have a higher risk of rupture than previously reported. Male patients and patients with noncalcified aneurysms appear to have a greater risk of rupture. beta-Blockade may have some protective effect against aneurysm rupture. Intervention is reasonable in all patients at good operative risk with SMA aneurysms, considering the high rupture rate in our series. (+info)
ET(A) receptor blockade protects the small intestine against ischaemia/reperfusion injury in dogs via an enhancement of antioxidant defences.
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The aim of the present study was to determine whether the ET(A) receptor antagonist LU135252 can protect the mesenterium against ischaemia/reperfusion (I/R) damage. Direct occlusion of the superior mesenteric artery was performed for 30 min in two groups of dogs. Declamping was followed by 90 min of reperfusion. Mesenteric release of ET-1 was studied in series 1 (n=6). In series 2, 5 min before cross-clamping, the treated group (n=7) received an intravenous bolus of LU135252 (5 mg/kg), whereas the control group (n=6) was given vehicle. Mean arterial blood pressure and mesenteric blood flow were recorded. Mesenteric venous and systemic arterial serum lactate and glucose, plasma creatine kinase and free radical concentrations were determined at 15 min intervals. Ischaemia for 30 min induced a significant increase (P<0.05) in mesenteric ET-1 release (1594+/-526 pg/min, compared with 343+/-258 pg/min at baseline), which had returned to baseline after 20 min of reperfusion. LU135252 administration significantly decreased mesenteric blood flow during ischaemia (204+/-23%) compared with controls (320+/-34%, P<0.05). In contrast, mesenteric blood flow was higher in the treated group (120+/-19% compared with 82+/-7%; P<0.05) after 90 min of reperfusion. Mesenteric lactate production was reduced by ET(A) antagonist administration under ischaemia (0.77+/-0.02 mmol/l) compared with controls (1.36+/-0.04 mmol/l; P<0.01). Lower levels of venous creatine kinase were present in the treated group during ischaemia as well as after reperfusion (120+/-7% compared with 150+/-16%; P<0.01). Administration of LU135252 also improved the total scavenger capacity of the mesenteric bed during ischaemia [(15.9+/-3.9)x10(6) compared with (6.4+/-3.6)x10(6) relative light units; P<0.05] and early reperfusion [(8.7+/-3.1)x10(6) compared with (1.1+/-2.9)x10(6) relative light units]. Thus ET-1 is involved in I/R-induced disturbances in the intestine. LU135252 seems to counteract these changes, in part by increasing the antioxidant capacity of the mesenterium. (+info)
Role of female sex hormones in neuronal nitric oxide release and metabolism in rat mesenteric arteries.
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This study examines the effects of female sex hormones on the vasoconstrictor response to electrical field stimulation (EFS), as well as the modulation of this response by neuronal NO. For this purpose, segments of denuded superior mesenteric artery from ovariectomized (OvX) female Sprague-Dawley rats and from control rats (in oestrus phase) were used. EFS induced frequency-dependent contractions, which were greater in segments from OvX rats than in those from control rats. The NO synthase inhibitor N(G)-nitro-l-arginine methyl ester strengthened EFS-elicited contractions to a greater extent in arteries from OvX rats than in those from control rats. Similar results were observed with the preferential neuronal NO synthase inhibitor 7-nitroindazole. The sensorial neurotoxin capsaicin did not modify EFS-induced contractions in segments from either group. In noradrenaline-precontracted segments, sodium nitroprusside (SNP) induced concentration-dependent relaxation, which was greater in segments from control rats than in those from OvX rats. 8-Bromo-cGMP induced similar concentration-dependent relaxation in noradrenaline-precontracted segments from both OvX and control rats. Diethyldithiocarbamate, a superoxide dismutase (SOD) inhibitor, reduced the relaxation induced by SNP in segments from both groups of rats. SOD, a superoxide anion scavenger, enhanced the relaxation induced by SNP in segments from OvX rats, but did not modify it in segments from control rats. EFS induced NO(-)(2) formation, which was greater in segments from OvX than in those from control rats, and pretreatment with tetrodotoxin, a blocker of nerve impulse propagation, abolished release in both cases. These results suggest that EFS induces greater neuronal NO release in mesenteric segments from OvX rats than in those from control rats and, although NO metabolism is also higher, the contribution of net neuronal NO in the vasomotor response to EFS is greater in segments from OvX rats than in those from control rats. (+info)
Urgent contrast enhanced computed tomography in the diagnosis of acute bowel infarction.
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Bowel infarction commonly presents as an acute abdomen that rapidly progresses to severe shock. The diagnosis is often not clinically suspected. Three cases are described where the diagnosis was made during dynamic contrast enhanced computed tomography (CT), when gas was demonstrated in the portal venous system and liver. Two patients died during surgery, the third survived because of the prompt diagnosis made on CT, and subsequent surgical treatment. The radiological findings are reviewed. (+info)
Spontaneous isolated dissection of the superior mesenteric artery.
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A case of a 63-year-old man with isolated dissection of the superior mesenteric artery (SMA), demonstrated by enhanced computed tomography (CT) and abdominal angiography, was admitted to our hospital. The severity of this disease varies from mild to severe; the severe cases require surgery. But the mild cases, like the one presented here, only need conservative therapy. This case demonstrated the usefulness of anticoagulation therapy and the indications for surgical and radiological intervention. (+info)
Disruption of the iliocolic artery after blunt trauma.
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Injury to the superior mesenteric artery and branches is an uncommon event, which is typically associated with penetrating injury and high mortality. A case is presented of rupture of a branch of the superior mesenteric artery (iliocolic artery) after blunt trauma. The case illustrates the more occult presentation and better overall prognosis associated with this type of injury as compared with injury to the proximal superior mesenteric artery. In addition this case highlights the importance of vigilance in patients who deteriorate after initial resuscitation. (+info)
Successful management in the case of mesenteric ischemia complicated with acute type a dissection.
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We report a case of acute type A dissection with ischemic enterocolitis due to blood flow insufficiency in the superior mesenteric artery. A 67 year-old man, with medicated ischemic heart disease and hypertension, presented to another hospital with chest pain radiating to the back and epigastrium. Contrast-enhanced computed tomography revealed a type A dissecting aneurysm, that extended from the ascending aorta to the left common iliac artery, with a 50-mm diameter in the ascending aorta. Celiac trunk and left renal artery arose from the false lumen, and the superior mesenteric artery (SMA) was compressed by the thrombosed false lumen. Symptoms of acute mesenteric ischemia clearly developed. Then, a large amount of tarry stool (melena) was discharged. First, an emergency saphenous vein bypass was performed from the common iliac artery to the superior mesenteric artery at the orifice of the ileocolic artery where it was free from dissection. Then total arch replacement was performed using cardiopulmonary bypass. The patient's postoperative course was uneventful, and the abdominal symptoms completely disappeared. This case demonstrates that prompt surgical relief of ischemia in major organs is important to save lives in the cases of acute aortic dissection with ischemic complications. (+info)
Nutcracker syndrome: an overlooked cause of hematuria.
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Nutcracker syndrome is caused by compression of the left renal vein between the aorta and the superior mesenteric artery, where it courses in the fork formed at the bifurcation of these arteries. The phenomenon results in left renal venous hypertension, which leads to left renal vein and left gonadal vein varices and unilateral hematuria. The main presenting symptom is hematuria, with or without left flank pain. The disorder is easily missed by routine diagnostic methods. Its incidence is likely underestimated. We report on a 25-year-old woman who experienced intermittent gross hematuria and left flank pain. The diagnosis of nutcracker syndrome was missed initially. Abdominal computed tomography, angiography, venography, and magnetic resonance angiography, which were later performed, showed that the left renal vein was compressed between the aorta and the superior mesenteric artery. The pressure gradient between the left renal vein and the inferior vena cava was 6.8 cm H2O. A diagnosis of nutcracker syndrome was established. She refused surgery and was lost to follow-up. The diagnosis and treatment of nutcracker syndrome are discussed. Magnetic resonance angiography is a safe and reliable tool for diagnosing this disorder. (+info)