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PubMedDate not supplied

[Closed loop intestinal obstruction: role of computerized tomography].

PURPOSE: The obstruction of a bowel segment at both ends results in a closed loop obstruction. Progression to strangulation frequently occurs if surgical intervention is delayed. The role of plain radiography in the diagnosis of closed loop obstruction and strangulation has been shown to be limited, while the recent literature has demonstrated the growing role of computed tomography (CT). This paper reports our experience in the study of closed loop obstruction by CT. MATERIAL AND METHODS: The CT studies of 12 patients with surgically confirmed closed loop obstruction were retrospectively reviewed. The following CT signs were used for the diagnosis: a) fluid-filled distended loops, b) C-shaped incarcerated loop, c) radial distribution of several dilated bowel loops and mesenteric vessels converging toward the point of obstruction, d) triangular or fusiform tapering of the closed loop and/or whirl sign in the site of obstruction. RESULTS: On the basis of these signs, the diagnosis was made in 11 of 12 patients. Only 1 patient, who had a negative CT study, was positive at a subsequent enteroclysis. CT findings of strangulation were associated in 3 cases: slight wall thickening with vascular congestion and mesenteric ascites, confirmed at surgery. DISCUSSION AND CONCLUSIONS: Small bowel obstruction can be distinguished into simple and closed loop obstructions. The latter is a more severe condition which is often complicated by strangulation with vascular impairment, edema and intramural and mesenteric hemorrhage. Consequent arterial insufficiency rapidly leads to ischemia, infarction and necrosis. The radiologist plays a role in the early recognition of the closed loop obstruction and of any sign of strangulation. The role of CT in the diagnosis and workup of patients with suspected intestinal occlusion has been analyzed in the literature with reported 63% sensitivity, 78% specificity and 66% accuracy. CT is also capable of revealing the causes of occlusion in 73-95% of cases. The above CT signs, as confirmed in our experience, allow to identify closed loop obstruction and also small bowel strangulation, thus supplying a valuable contribution to diagnosis and accurate preoperative evaluation. We conclude that CT can accurately demonstrate the presence of closed loop obstruction and can be the technique of choice in patients in whom obstruction is associated with clinical signs suggestive of strangulation.

Female↗

PubMed1980

An experimental study on gastroschisis using fetal surgery.

Gastroschisis models were successfully created in three groups of fetal rabbits by means of fetal surgery. Anatomical and pathologic assessments were carried out on the neonates that had experimental gastroschisis. In group I surgery was performed on the fetuses of 21 days gestational age; in group II on the fetuses of 23 days; and in group III on the fetuses of 26 days, respectively. Five cases of experimental gastroschisis were made in each group. The body weights of those with gastroschisis were low as compared with those of normal neonates. Intestinal length decreased and wall thickness increased as the result of 5--10 days evisceration. Abdominal cavity decreased in volume in all cases and could not accommodate the eviscerated organs. The number and density of distal mesenteric vessels (vasa recta) was high in the shortened intestine in gastroschisis models. Therefore it can be reasonably assumed that the intestine is only contracted and the possibility of return to normal length remains.

Abdominal Muscles↗

PubMed1992

In vitro hyporeactivity to methoxamine in portal hypertensive rats: reversal by nitric oxide blockade.

The endothelial cell plays an important role in the local control of vascular smooth muscle tone. Portal hypertension is accompanied by systemic vasodilatation and a decreased response to vasoconstrictors, changes especially evident in the superior mesenteric arterial bed. To evaluate a possible effect of the locally released endothelium-derived relaxing factor nitric oxide (NO), we tested the effect of NO blockade in in vitro perfused superior mesenteric arterial beds of normal (sham) and portal hypertensive (PVL) rats, induced by partial portal vein ligation. A significant (n = 7/group; P = 0.02) hyporeactivity to the vasoconstrictive properties of the alpha-adrenoceptor agonist methoxamine (3 x 10(-6) to 3 x 10(-4) M) was prevented by blocking NO formation in PVL compared with sham rats, using the stereospecific biosynthesis antagonist N omega-nitro-L-arginine (10(-4) M, n = 7/group; NS for all methoxamine concentrations tested). This effect was reversed by the NO precursor L-arginine (10(-3) M, n = 5/group). In conclusion, these in vitro results in mesenteric vessels demonstrate that 1) portal hypertension is accompanied by a hyporeactivity to the vasopressor methoxamine and 2) locally released NO in this preparation is responsible for the decreased vasoconstrictive response.

Acetylcholine↗

PubMedDate not supplied

Differential changes of prostanoid synthesis by the gastrointestinal tract, mesenteric vasculature and hepatic portal vein of diabetic rats: comparison between pair and ad libitum feeding.

The synthesis of the prostaglandins (PG) I2 (measured as 6-oxo-PGF1 alpha), E2, E2 alpha) and thromboxane (TX) A2 (measured as TXB2) by the mucosal and muscular portions of the stomach, duodenum, jejunum, ileum, mesenteric vessels, hepatic portal vein and two arteries (carotid and aorta) was investigated in long term streptozotocin-induced diabetes mellitus (DM; fed ad libitum and pair fed). In all regions of the gastrointestinal tract there were no changes in PG synthesis (per unit weight of tissue) in diabetic rats (pair fed or fed ad libitum) compared to controls. However, there were marked increases in PG synthesis (up to 3 fold) by the mesenteric vasculature and hepatic portal vein in diabetic animals fed ad libitum and in pair fed diabetic rats and decreases in the aorta and carotid artery. These data suggest that increases in PG synthesis by the splanchnic vasculature may constitute a specific adaptive response to DM. The similarity of the responses of pair fed rats to those of rats fed ad libitum indicates that DM and not hyperphagia is the likely determinant of these adaptive changes. Given that increased splanchnic blood flow enhances nutrient uptake (both known to occur in DM), the increase in splanchnic vascular PG synthesis, in particular of vasodilatory PGI2, may contribute to enhanced nutrient uptake.

Animals↗

PubMed2002

Prophylactic use of epidermal growth factor reduces ischemia/reperfusion intestinal damage.

Ischemia/reperfusion of mesenteric vessels is a useful model for acute vascular insufficiency and the early stages of multiorgan failure, conditions associated with high morbidity and mortality. Epidermal growth factor (EGF) is a potent mitogen that shows potential for use in intestinal injury. We therefore examined its influence on this model. Male Sprague-Dawley rats received human recombinant EGF (2 mg/kg i.p., n = 14) or saline (n = 16); 25 minutes before arterial clamping of the superior mesenteric artery (ischemic period) for 60 minutes followed by a final 60-minute reperfusion period. Additional rats were not operated on (controls, n = 7) or had sham operation (laparotomy only, n = 10). Ischemia/reperfusion caused macroscopic damage affecting 56%, 51 to 67% (median, interquartile range), of small intestinal length and intraluminal bleeding. Malondialdehyde levels (free radical marker) increased eightfold compared to nonoperated animals (2400, 2200 to 2700 micro mol/mg protein versus 290, 250 to 350 micro mol/mg protein, P < 0.01) and myeloperoxidase levels (marker for inflammatory infiltrate) increased 15-fold (3150, 2670 to 4180 U/g tissue versus 240, 190 to 250 U/g tissue, P < 0.01). Pretreatment with EGF reduced macroscopic injury to 11%, 0 to 15%; prevented intraluminal bleeding; and reduced malondialdehyde and myeloperoxidase levels by approximately 60% and 90% (all P < 0.01 versus non-EGF-treated). Mesenteric ischemia/reperfusion also damaged the lungs and kidneys and increased serum tumor necrosis factor-alpha levels (circulating cytokine activity marker). EGF pretreatment also reduced these changes. These studies provide preliminary evidence that EGF is a novel therapy for the early treatment or prevention of intestinal damage and multiorgan failure resulting from mesenteric hypoperfusion.

Animals↗

PubMedDate not supplied

Progress in chronic mesenteric arterial ischemia.

Analysis of surgical treatment for chronic mesenteric arterial occlusive lesions in 45 patients between 1964 and 1986 has shown an evolution in diagnostic criteria, indications for operation, and surgical technique. Prior to 1976, a variety of surgical procedures (diaphragmatic crus release, arterial dilation, patch angioplasty, reimplantation, endarterectomy) were employed in treatment of patients with a wide range of symptoms and variation in number of mesenteric vessels involved. Since 1976, we have selected patients with "typical" symptoms (postprandial epigastric pain, fear of eating, weight loss) and 2 or 3 vessel disease, and have avoided surgery for celiac crus lesions. Typical symptoms were seldom present in isolated celiac artery crus compression, 4 of 15 pts (23%), but were often present with 2 or 3 vessel disease, 17 of 28 pts (61%, p = 0.03). Satisfactory resolution of pain was achieved in 18 of 24 pts with 2 or 3 vessel disease. We conclude that presence of "typical" symptoms and angiographic findings of 2 or 3 vessel disease are prerequisites for effective surgical treatment. Bypass graft is our surgical technique of choice, but the extent of arterial reconstruction required to relieve symptoms remains undefined.

Adolescent↗

PubMed1989

[Sonographic diagnosis of acute intestinal ischemia].

Acute intestinal ischaemias, which are associated with a high mortality of 70-90 per cent, are properly identified in only about 50% of the cases despite the use of update imaging methods. Improvement of the unfavourable prognosis appears possible if diagnosis is effected early enough. With the help of high-resolution real time sonographic equipment--as far as possible with 5 MHz linear or convex transducers--ischaemic changes of the intestinal wall can be detected. However, a sophisticated examination technique is necessary. The following findings must be sought for, depending on the degree of severity and the stage of the mesenterial disturbance of blood flow: Oedematous swelling of the intestinal wall; intramural air ("pneumatous intestinalis"); free liquid; free air; possibly also air in the portal venous system. If the conditions of examination are favourable, it is also possible to identify the relevant stenose or occlusions at the mesenteric vessels by means of Duplex sonography. Sonography is well suited for acute diagnosis and follow-up assessment of intestinal flow disturbances. Angiography should be used preoperatively and to clarify the problem of non-occlusive types of intestinal ischaemia.

Cecum↗

PubMed1988

Afferent electrical stimulation of mesenteric nerves inhibits duodenal HCO3- secretion via a spinal reflex activation of the splanchnic nerves in the rat.

The experiments were performed on male Sprague-Dawley rats anaesthetized with chloralose. Duodenal HCO3- secretion was measured in situ by pH-stat titration. The nerves bundles surrounding two randomly chosen mesenteric vessels were electrically stimulated (3 Hz, supramaximal intensity) in the afferent direction. This was done in order to mimic the intestino-intestinal spinal reflex activation of the splanchnic sympathetic fibres. The procedure reduced duodenal HCO3- secretion by 20% together with an increase in mean arterial pressure and heart rate. Duodenal HCO3- secretion decreased similarly in control rats and in those subjected to a cervical cord transection, whereas animals with bilaterally cut splanchnic nerves did not respond to such mesenteric nerve stimulation. Pharmacological pretreatment with guanethidine or yohimbine, but not prazosin, inhibited the reduction in duodenal HCO3- secretion. Thus the data suggest that electrical stimulation of mesenteric afferent nerves inhibits duodenal HCO3- secretion via a spinal reflex activation of splanchnic sympathetic nerve fibres to the duodenum, and that the response is mediated via alpha 2 adrenoceptors.

Afferent Pathways↗

PubMed2006

Intrinsic pump-conduit behavior of lymphangions.

Lymphangions, segments of lymphatic vessels bounded by valves, have characteristics of both ventricles and arteries. They can act primarily like pumps when actively transporting lymph against a pressure gradient. They also can act as conduit vessels when passively transporting lymph down a pressure gradient. This duality has implications for clinical treatment of several types of edema, since the strategy to optimize lymph flow may depend on whether it is most beneficial for lymphangions to act as pumps or conduits. To address this duality, we employed a simple computational model of a contracting lymphangion, predicted the flows at both positive and negative axial pressure gradients, and validated the results with in vitro experiments on bovine mesenteric vessels. This model illustrates that contraction increases flow for normal axial pressure gradients. With edema, limb elevation, or external compression, however, the pressure gradient might reverse, and lymph may flow passively down a pressure gradient. In such cases, the valves may be forced open during the entire contraction cycle. The vessel thus acts as a conduit, and contraction has the effect of increasing resistance to passive flow, thus inhibiting flow rather than promoting it. This analysis may explain a possible physiological benefit of the observed flow-mediated inhibition of the lymphatic pump at high flow rates.

Animals↗

PubMed1995

Acute mesenteric ischemia.

The term acute mesenteric ischemia (AMI) is applied to a wide spectrum of bowel injury within the distribution of the superior mesenteric vessels, ranging from reversible alterations in bowel function to transmural necrosis of the bowel wall. Intensivists not only are called upon to manage this catastrophic disease but also may be faced with AMI as a consequence of other illnesses that they treat.

Acute Disease↗

PubMed1998

Impaired function of alpha-2 adrenoceptors in smooth muscle of mesenteric arteries from spontaneously hypertensive rats.

The alpha2-adrenoceptor function in mesenteric arteries of spontaneously hypertensive rats (SHR) was investigated by comparing membrane potential changes in response to adrenergic agonists in preparations from female SHR, Wistar-Kyoto (WKY) and normotensive Wistar rats (NWR). Resting membrane potential was found to be less negative in mesenteric arteries from SHR than in those from NWR and WKY. Apamin induced a decrease in the membrane potential of mesenteric artery rings without endothelium from NWR and WKY, but had no effects in those from SHR. Both UK 14,304 and adrenaline, in the presence of prazosin, induced a hyperpolarization that was significantly lower in de-endothelialized mesenteric rings from SHR than in those from NWR and WKY. In mesenteric rings with endothelium, however, similar hyperpolarization was observed in the three strains. In NWR mesenteric rings with endothelium the hyperpolarization induced by activation of alpha2-adrenoceptors was abolished by apamin, whereas in intact SHR mesenteric rings this hyperpolarization was slightly reduced by apamin and more efficiently reduced by Nomega-nitro-L-arginine. It is concluded that the activity of potassium channels coupled to alpha2-adrenoceptors is altered in the smooth muscle cells of SHR mesenteric arteries, contributing to their less negative membrane potential. On the other hand, the endothelial alpha2-receptors are functioning in mesenteric vessels from SHR and their stimulation induces a hyperpolarization mainly through the release of nitric oxide.

Adrenergic alpha-Agonists↗

PubMed2005

Early retropancreatic dissection during pancreaticoduodenectomy.

BACKGROUND: During pancreaticoduodenectomy, early neck division may be inadequate, particularly in cases of replaced or accessory right hepatic artery (RHA) or diffuse intraductal papillary and mucinous neoplasm (IPMN) or when invasion of superior mesenteric artery is suspected. METHODS: Modification of the technique of pancreaticoduodenectomy with dissection of the superior mesenteric vessels performed from behind the head of the pancreas before any pancreatic or digestive transection. The pancreas is divided later, after adequate mobilization of the specimen from the vessels, on either the neck or the body, according to underlying disease. RESULTS: We used this technique successfully in 20 patients with a replaced or accessory RHA, which was successfully preserved in 19; one patient had inadvertent division of a 2-mm diameter accessory RHA that was ligated with no postoperative complications. Additionally, we used this technique in 18 patients with IPMN-14 pancreaticoduodenectomies extended to the body and 4 total pancreatectomies-and in 3 patients with adenocarcinoma involving the porto-mesenteric confluence and needing en-bloc vascular resection. CONCLUSIONS: Early division of retroperitoneal margin is a useful technical variant of pancreaticoduodenectomy, which can be recommended in selective indications to improve safety and radicality of the procedure.

Carcinoma, Pancreatic Ductal↗

PubMed1989

[Non-occlusive mesenteric ischemia in patients undergoing maintenance hemodialysis].

Non occlusive mesenteric ischaemia is a serious complication of maintenance haemodialysis. Its physiopathological mechanisms are controversial and its frequency is underestimated. Eight cases (in 5 patients) are reported: the clinical syndrome consisted of acute abdominal pain without evidence of shock or abdominal wall rigidity at palpation, associated with hyperleucocytosis and hyperkaliemic acidosis. The normality of the mesenteric vessels was confirmed at autopsy in one patient and during surgery in all others. Two patients were found to have caecal necrosis, 2 had diffuse necrotizing enterocolitis and 1 had necrosis of the left colon. The prognosis of this complication is sombre: 4 of our 5 patients died, including 3 who had relapsed 1, 4 and 18 months respectively after surgery (diffuse ileocolic necrosis). The usually accepted physiopathological mechanism is volaemic contraction consecutive to haemodialysis in often atheromatous subjects; however, the fact that the mesenteric infarction is not occlusive, that it occurs sometime after the end of the haemodialysis session and above all, the lack of haemodynamic changes during or immediately after the session suggest that other factors (bioincompatibility) are involved.

Abdomen, Acute↗

PubMed1993

Portal vein thrombosis in a child with homozygous sickle-cell disease.

A 13-year-old boy with homozygous sickle-cell (SS) disease died suddenly at home following a short history of abdominal pain. Autopsy revealed venous thrombosis of the hepatic, portal, superior mesenteric and splenic veins. Venous thrombosis is rare in SS disease and thrombosis of mesenteric vessels is most frequently seen in chronic myeloproliferative disorders. Its occurrence in SS disease raises the possibility of a common pathogenesis and adds another pathology to the causes of the abdominal painful crisis.

Abdominal Pain↗

PubMedDate not supplied

Predicting resectability of periampullary cancer with three-dimensional computed tomography.

The radiographic assessment of extent of tumor burden and local vascular invasion appears to be enhanced with three-dimensional computed tomography (3D-CT). The purpose of this study was to evaluate the impact of preoperative 3D-CT in determining the resectability of patients with periampullary tumors. Intraoperative findings from exploratory laparotomy were gathered prospectively from 140 patients who were thought to have periampullary tumors and were deemed resectable after undergoing preoperative 3D-CT imaging. CT findings were compared to intraoperative findings, and the accuracy of 3D-CT in predicting tumor resectability and, ultimately, the likelihood of obtaining a margin-negative resection were assessed. Of the 140 patients who were thought to have resectable periampullary tumors after preoperative 3D-CT, 115 (82%) were subsequently determined to have periampullary cancer. The remaining 25 patients had benign disease. Among the patients with periampullary cancer, the extent of local tumor burden involving the pancreas and peripancreatic tissues was accurately depicted by 3D-CT in 93% of the patients. 3D-CT was 95% accurate in determining cancer invasion of the superior mesenteric vessels. Preoperative 3D-CT accurately predicted periampullary cancer resectability and a margin-negative resection in 98% and 86% of patients, respectively. For patients with pancreatic adenocarcinoma (n=85), preoperative 3D-CT resulted in a resectability rate and a margin-negative resection rate of 79% and 73%, respectively. The ability of 3D-CT to predict a margin-negative resection for periampullary cancer, including pancreatic adenocarcinoma, relies on its enhanced assessment of the extent of local tumor burden and involvement of the mesenteric vascular anatomy.

Adenocarcinoma↗

PubMed1993

Vascular remodeling in systemic hypertension.

It is now well accepted that treatment of hypertension must extend beyond the mere control of blood pressure. Among the objectives "beyond blood pressure control" is the remodeling of resistance and compliance vessels that have usually undergone a process of hypertrophy and/or hyperplasia. Salutary vascular remodeling by antihypertensive treatment not only implies structural changes of the vascular wall, but also functional improvements, including diminished contractile responses to endogenous vasoconstrictors and enhanced relaxation to endogenous vasodilators. We have treated spontaneously hypertensive rats with the angiotensin-converting enzyme (ACE) inhibitors zabicipril, perindopril, and ramipril at antihypertensive and sub-antihypertensive doses and have analyzed vascular morphology and function. Chronic oral treatment was begun before hypertension developed (prevention study). Remodeling of mesenteric vessels with, inter alia, a reduction of the media:lumen ratio was achieved by antihypertensive doses of the drugs. Further, vascular function was improved not only after high-dose, but also after low-dose ACE inhibitor treatment, as tested in the aortic vessels: an inhibition of vascular ACE was associated with attenuated vasoconstrictor responses to norepinephrine and enhanced dilator responses to acetylcholine. In addition, low and high doses significantly increased aortic cyclic guanosine monophosphate (cGMP) content, suggesting an improved vasodilator capacity. Our data demonstrate that improvements of vascular function can be achieved by ACE inhibitors, independently of structural changes and of the antihypertensive action exerted by these drugs.

Acetylcholine↗

PubMedDate not supplied

Diagnosis of acute intestinal ischemia by color Doppler sonography. Color Doppler sonography and acute intestinal ischemia.

Detection of acute intestinal ischemia is a diagnostic challenge. Color Doppler sonography of the abdomen may contribute to its diagnosis by showing lesions of the gut wall associated with occlusion or stenosis of the mesenteric vessels. Our overview of the sonographic findings of acute intestinal ischemia is presented as well as a proposition of algorithm for the working up to the diagnosis based on recent clinical experience.

Arterial Occlusive Diseases↗

PubMedDate not supplied

Transcatheter occlusion of inferior mesenteric arteriovenous fistula: a case report.

Transcatheter embolization of the inferior mesenteric artery with steel coils was performed for the control of massive lower gastrointestinal bleeding and sepsis. The bleeding and sepsis was caused by a very large arteriovenous fistula of the inferior mesenteric vessels. This iatrogenic lesion developed and became symptomatic just 5 weeks after an anterior resection of the rectum was performed. Following embolization, the patient made a speedy recovery from the sepsis and no recurrent bleeding was noted.

Arteriovenous Fistula↗