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PubMed1991

The effects of temporary occlusion of the superior mesenteric vein or splenic vein on biliary bilirubin and bile acid excretion in rats.

To elucidate the possible implication of hepatic blood supply to the occurrence of hepatolithiasis, the rat superior mesenteric vein, which drains blood from the intestine, or the splenic vein, which drains from the spleen, was occluded for 30 minutes. Changes in the hepatic oxygen saturation index, intrahepatic uridine diphosphate-glucuronic acid concentration, bile flow, and the excretion of bilirubin as well as its fraction, along with bile acid in bile before and after the procedure, were observed. In association with superior mesenteric vein occlusion, oxygen saturation index, hepatic uridine diphosphate-glucuronic acid concentration, bile flow, bile acid concentration in bile, and percentage of biliary bilirubin diglucuronide were all decreased. Incubation of bile under sterile conditions from rats with occluded superior mesenteric veins resulted in precipitation of mainly calcium salt of fatty acid. In contrast, splenic vein occlusion caused no changes except for a decrease in biliary bilirubin concentration. Incubation of bile from rats with occluded splenic veins did not induce precipitation. From these findings it can be concluded that blood flow in the superior mesenteric vein is the primary source of oxygen supply to the rat liver and that this vein plays an important role in maintaining bile flow, bile acid excretion, and bilirubin conjugation and in preventing the precipitation of bile (possibly preventing hepatolithiasis).

Animals↗
PubMedDate not supplied

Safety of portal vein resection using centrifugal pump-assisted venous bypass between the superior mesenteric vein and the umbilical vein.

BACKGROUND/AIMS: To achieve complete resection of pancreatic cancer, portal vein resection has been performed with increasing frequency at the time of pancreaticoduodenal resection (pancreaticoduodenectomy or total pancreatectomy). In the meantime, visceral congestion and liver ischemia are of great concern during the procedure. We investigated safety of portal vein resection using a centrifugal pump-assisted bypass between the superior mesenteric vein and the umbilical vein. METHODOLOGY: A retrospective comparison was performed in 49 consecutive patients who underwent pancreatoduodenal resection with or without portal vein resection using the bypass for pancreatic cancer. Twenty-two patients underwent portal vein resection using the bypass (group 1). The other 27 patients undergoing pancreatoduodenal resection without portal vein resection comprise the control group (group 2). RESULTS: Total operative time was 756 +/- 159 min and 526 +/- 109 min (p<0.001) and median blood loss was 2090 mL and 1200 mL in groups 1 and 2, respectively. However, the centrifugal pump-assisted bypass allowed stable bypass flow, and neither intestinal edema nor ischemic change of the liver was observed during portal vein resection and the subsequent reconstruction. Postoperatively, the peak postoperative AST, ALT and total bilirubin levels showed no significant difference and postoperative day of starting a liquid diet was similar between the groups (9.0 +/- 5.4 vs. 9.8 +/- 3.8 days, p=0.48). In addition, the rates of morbidity (55% vs. 48%) including biliary and pancreatic leak as well as mortality (9% vs. 4%) did not significantly differ between the 2 groups. CONCLUSIONS: The centrifugal pump-assisted bypass may be useful to prevent hepatic ischemia and visceral congestion during portal vein resection procedures, resulting in similar postoperative outcomes to the control after pancreaticoduodenal resection for pancreatic cancer.

Aged↗
PubMed1996

Anatomical differences in responsiveness to vasoconstrictors in the mesenteric veins from normal and portal hypertensive rats.

The present study evaluates the effects of pre-hepatic portal hypertension, induced in rats by partial portal vein ligation, on the responsiveness of rostral (proximal) and caudal (distal) rings from the mesenteric vein. The anatomical origin of the sample influenced the response to vasoconstrictors in sham-operated animals, and this pattern of reactivity was specifically modified in portal-ligated rats. In veins from sham-operated rats, contraction induced by a submaximal concentration of KCl (60 mM) was greater in proximal than in distal rings. Vasopressin and 5-hydroxytryptamine contracted mainly distal rings, methoxamine showed a greater effect on proximal rings, and endothelin-1 and angiotensin-II contracted vein rings independently of their anatomical origin. In veins from portal hypertensive rats, response to KCl (60 mM) were increased in distal rings, and all rings exhibited enhanced reactivity to vasopressin and 5-hydroxyptyptamine as well as attenuation of the response to methoxamine. Responses to endothelin-1 were decreased in proximal vein rings from portal hypertensive rats whereas responses to angiotensin-II were not influenced by the anatomical origin. Incubation with atropine, propranolol or indomethacin, did not modify the responses to vasopressin and 5-hydroxytryptamine in tissues from either sham-operated or portal hypertensive animals. Likewise, the hyporeactivity to methoxamine and endothelin-1 in rings from portal hypertensive rats persisted in the presence of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester. These results suggest the physiological existence of anatomical differences in the responsiveness to vasoconstrictors throughout the mesenteric vein and that changes in the responsiveness of the mesenteric vein induced by portal hypertension are specific for each agonist and possibly result from individual variations at a receptor or post-receptor level.

Animals↗
PubMed1995

Simultaneous measurement of flow in the superior mesenteric vein and artery with cine phase-contrast MR imaging: value in diagnosis of chronic mesenteric ischemia. Work in progress.

PURPOSE: To evaluate the use of measurements of blood flow in the superior mesenteric vein (SMV) and superior mesenteric artery (SMA) simultaneously acquired with phase-contrast cine magnetic resonance (MR) imaging for diagnosing chronic mesenteric ischemia. MATERIALS AND METHODS: Simultaneous measurements of flow in the SMV and SMA were obtained in six healthy volunteers and eight patients with angiographically proved SMA stenosis (six asymptomatic, two symptomatic). Flow dynamics in both vessels were correlated with the degree of arterial disease seen at angiography and with the presence or absence of ischemic symptoms. RESULTS: Postprandial SMV and SMA flow increased substantially less in patients with atherosclerosis than in volunteers. Comparison of simultaneous SMV and SMA flow measurements provided more information about collateral flow to and from the mesenteric circulation than did either the SMV or SMA flow measurement alone. CONCLUSION: Simultaneous SMV and SMA flow measurement with cine phase-contrast MR imaging may be useful in diagnosing and understanding chronic mesenteric ischemia.

Adult↗
PubMed1993

Ultrastructural analysis of sympathetic neuromuscular junctions on mesenteric veins of the guinea pig.

This study reports on the detailed ultrastructure of sympathetic postganglionic varicose axon terminals on mesenteric veins leading from the ileum of the guinea pig and in particular the structural arrangement of the varicosities with venous smooth muscle cells. The response to nerve stimulation in veins has a long time course and it has been suggested that this reflects a wide separation between the site of transmitter release and the receptors on the effector cell membrane. The aim of this study was to determine the distance between individual sympathetic varicosities and smooth muscle cells in mesenteric veins. Fluorescent histochemical preparations of the sympathetic innervation of the different branches of mesenteric veins indicate the branching network of varicose axons around the vessel to be relatively dense. Electron micrographs show the innervation to be confined to the adventitia close to the medio-adventitial border and to be predominantly catecholaminergic. A serial section ultrastructural analysis of the relationship of the varicosities with the outer smooth muscle cells showed that almost all (98%) of the exposed axon varicosities in the adventitia formed neuromuscular junctions. Three-dimensional reconstructions from serial sections of individual varicosities have shown that the junctions have structural specialisations identical to neuromuscular junctions described on arterial vessels and similar to those found at skeletal neuromuscular junctions. The density of neuromuscular junctions on the veins was found to be similar to that on the corresponding artery in the same animal. We suggest that in veins, noradrenaline is released focally at neuromuscular junctions.

Animals↗
PubMedDate not supplied

Portal vein absence and nodular regenerative hyperplasia of the liver with giant inferior mesenteric vein.

We present a patient with nodular regenerative hyperplasia of the liver (NRH) and portal vein absence studied with CT, MR imaging, and MR angiography. The most striking feature was exuberant hemorrhoids due to a giant hepatofugal inferior mesenteric vein. A relationship between unbalanced portal blood flow and nodular regenerative transformation of the liver is suggested in this patient.

Adolescent↗
PubMedDate not supplied

Refractory proctosigmoiditis probably caused by inferior mesenteric vein ligation at sigmoidectomy.

A case of refractory proctosigmoiditis is reported in a 65-year-old female post-sigmoidectomy patient. She had bloody diarrhea and abdominal pain 2 years after sigmoidectomy, in which the inferior mesenteric vein was ligated close to the inferior mesenteric artery root during the lymph node dissection, while the inferior mesenteric artery trunk and the last branch of the sigmoid arteries was preserved. The biopsied specimen obtained by a fiber optic colonoscopy was diagnosed as proctitis. Antidiarrheals, 5-aminosalicylic acid and steroid enemas showed only limited therapeutic effects. An angiography revealed a mild degree of rectal artery dilatation and tiny venous angiogenesis detected on the delayed phase images. Because the inferior mesenteric vein had been ligated, collateral veins developed to drain the blood on the distal side of the anastomosis to bilateral internal iliac veins. The venous blood of the descending colon (oral side of anastomosis) drained to left colic vein. The cause of rectosigmoiditis was considered to be venous congestion due to the inferior mesenteric vein ligation. A rectosigmoidectomy with reanastomosis using a double-stapling technique was performed, and the patient was discharged without symptoms.

Aged↗
PubMed1997

Characterization of alpha-adrenoceptors in canine mesenteric vein.

The alpha-adrenergic receptors (alpha-ARs) in canine mesenteric vein (DMV) were studied by using nonselective agonists and selective antagonists in functional studies and in ligand binding to classify the subtypes present. Based on functional studies of phenylephrine (PE)-induced contractions and ligand-binding interactions of [3H]-prazosin with prazosin (PR), WB 4101 (WB), 5-methylurapidil (5-MU), BMY 7378, and SK&F 105854, and pretreatment with chloroethylclonidine (CEC), DMV alpha1-ARs resembled the alpha1D subtype. However, the affinity of PR assessed in functional and ligand-binding studies was less (pK(B,D,i) < or = 9) than expected from previous characterization of cloned rat or human alpha1-AR (pKi > or = 10). Interactions with 5-MU, BMY 7378, or SK&F 105854 suggested the presence of some alpha1-ARs that were not typical of alpha1D-AR and that binding and functional interactions did not yield corresponding results. PR binding was abolished by treatment with CEC, contractile responses to PE were reduced in Emax, and the concentration-effect curve shifted to the left, as previously reported. DMVs contracted in response to alpha2-AR agonists and were studied when contractions were potentiated by increasing extracellular KCl to 20 mM. Rauwolscine (RAU) had K(B) values at these sites consistent with K(D) values in binding studies. CEC had no effect on RAU binding in DMV. Ligand-binding studies to [3H]-RAU sites did not reveal a clear identification of subtype, but these alpha2-ARs were clearly not alpha2B-ARs. We conclude that canine mesenteric vein contains alpha1D-like ARs, but with significant differences, and an unclassifiable alpha2-AR. There may also be a smaller population of other, not alpha1D-like ARs, receptors, mediating responses to PE and binding of prazosin.

Adrenergic alpha-Agonists↗
PubMed1981

Effects of endogenous and exogenous noradrenaline on the smooth muscle of guinea-pig mesenteric vein.

Membrane responses of smooth muscles of the guinea-pig mesenteric vein to noradrenaline released from perivascular nerves or applied exogenously were investigated.1. Exogenously applied noradrenaline depolarized the muscle membrane at concentrations of over 10(-6)m, and generated slow waves or action potentials. Application of phentolamine but not propranolol suppressed the depolarization.2. The depolarization induced by exogenous noradrenaline was associated with increase in the membrane resistance. The level of the membrane depolarization was modified by changing [K](o), but not by [Na](o) or [Cl](o).3. Repetitive but not single stimulation of the nerves produced slow depolarization of the membrane. The amplitude of the slow depolarization was dependent on the frequency or number of stimuli within a certain range, but beyond this an increased frequency or an increased number of stimulating pulses produced no further increase in amplitude of the slow depolarization.4. The slow depolarization induced by nerve stimulation was analysed in relation to the diffusion of transmitter. The rising phase of the slow depolarization fitted well with the theoretically predicted one, while the falling phase did not.5. Stimulation of nerves with a high frequency and a large number of pulses produced slow waves or action potentials superimposed on the slow depolarization of the membrane.6. Membrane responses induced by nerve stimulation did not appear in the presence of TTX or phentolamine. TEA enhanced the nerve-induced responses.7. Myogenic electrical activities insensitive to TTX and phentolamine were recorded from the mesenteric vein. These activities were induced by nerve stimulation only in the fresh tissues, were usually irregular in shape, size and frequency, and lasted for 5-20 min.8. It was concluded that alpha-adrenergic receptors on the muscle membrane reacted in a similar manner to noradrenaline either released from the nerves or applied exogenously. Noradrenaline depolarized the muscle membrane by the decrease in potassium conductance of the membrane.

Animals↗
PubMed1989

Comparison of the prejunctional beta-adrenoceptor stimulating actions of adrenaline and isoprenaline in the dog mesenteric vein.

1. The prejunctional beta-adrenoceptor stimulating actions of adrenaline and isoprenaline were compared by recording junction potentials from smooth muscle cells of the dog mesenteric vein. 2. The potency of adrenaline and isoprenaline on beta-adrenoceptors in the postjunctional membrane was estimated from hyperpolarization of the membrane in smooth muscle cells of the guinea-pig facial vein. In the presence of yohimbine, both agents hyperpolarized the membrane to a similar extent. 3. In the dog mesenteric vein, amplitude of the excitatory junction potential (e.j.p.) and slow depolarization was inhibited by adrenaline and potentiated by isoprenaline; the former but not the latter was accompanied by depolarization of the smooth muscle membrane. 4. In the presence of yohimbine, adrenaline inhibited the e.j.p. without depolarization of the smooth muscle membrane; the action was weaker than in the absence of yohimbine. The isoprenaline-induced potentiation of the e.j.p. was further enhanced by yohimbine. 5. It is concluded that adrenaline and isoprenaline have similar stimulating actions on postjunctional beta-adrenoceptors in the guinea-pig facial vein, but have different actions on prejunctional beta-adrenoceptors in the dog mesenteric vein; isoprenaline but not adrenaline stimulates this beta-adrenoceptor to facilitate the release of transmitter substances from perivascular noradrenergic nerves.

Adrenergic beta-Agonists↗
PubMed2001

Ischaemic jejunal stenosis complicating portal and mesenteric vein thrombosis: a report of two cases.

A major complication of portal and mesenteric vein thrombosis is acute bowel ischaemia resulting in infarction and requiring immediate resection of the involved segment. Sufficient collaterals can prevent acute haemorrhagic infarction, but bowel stenosis due to chronic ischaemia may develop. We report two cases of ischaemic jejunal stenosis occurring 4 weeks after successful treatment of portal and mesenteric vein thrombosis. Diagnosis of high-grade segmental stenosis of the jejunum was established by contrast medium radiography of the gastrointestinal tract. After laparotomy and resection of the stenosed jejunal segment, both patients recovered well from the operation and were released from hospital. Follow-up examinations revealed an unremarkable state of health. Ischaemic bowel stenosis should be considered in patients with recurring abdominal pain after mesenteric and portal vein thrombosis. A close follow-up of every patient after treatment for mesenteric and portal vein thrombosis should be carried out to ensure early diagnosis of this complication.

Adult↗
PubMedDate not supplied

Two-step portal bypass to reconstruct an invaded superior mesenteric vein in pancreatic cancer.

Advanced cancer of the pancreatic head, especially in its caudal portion, has a limited surgical resectability due to its frequent invasion to the superior mesenteric vein (SMV). A patient with advanced carcinoma of the pancreatic head with vascular invasion to the major bifurcation of the SMV, underwent a pancreatico-duodenectomy under a two-step passive bypass of the portal flow. The marginal colic veins were dilated and formed a long collateral route to the inferior mesenteric vein and the splenic vein due to stenosis of the SMV. The venous flow in this vein was then easily interrupted with the surgical manipulation of the transverse colon. The first passive bypass was thus inserted into the accessory right colic vein to preserve the venous return from both the small intestine and the colon, and also to enable surgical dissection of the invaded SMV itself. After a thorough dissection of the invaded SMV, a second bypass was inserted into the main trunk of the SMV through the dissected vascular stump. Subsequently the passive bypass was maintained until the portal reconstruction with an interposition of the left common iliac vein could be performed. The patient recovered well from the surgery without any complications throughout the postoperative course. In summary, the two-step portal bypass describes, is thus considered a stable and safe procedure for the reconstruction of the superior mesenteric vein, during pancreatoduodenectomy for advanced carcinoma of the pancreatic head.

Angiography↗
PubMed1997

Anatomic variants of mesenteric veins: depiction with helical CT venography.

OBJECTIVE: The purpose of this study was to describe the variable anatomy of mesenteric veins on axial CT images and on volume-rendered CT venograms that use maximum intensity projection and shaded-surface display. SUBJECTS AND METHODS: Fifty-seven patients undergoing helical CT of the pancreas were included in the study. The mesenteric venous system was analyzed in 54 patients. Three patients were excluded because the helical CT data were unsatisfactory. RESULTS: On helical CT with maximum intensity projection and shaded-surface display, the superior mesenteric vein (SMV) was seen as a single trunk of variable length in 40 patients. In seven other patients, two mesenteric trunks merged separately with the splenic vein. In the remaining seven patients, the SMV was occluded by tumor. The inferior mesenteric vein drained into the splenic vein in 28 patients (56%), into the SMV in 14 patients (26%), and into the splenomesenteric angle in nine patients (18%). CONCLUSION: Both axial and volume-rendered CT venograms accurately reveal the variable mesenteric venous anatomy. CT venograms may replace conventional angiography in presurgical planning.

Female↗
PubMed1993

A case of protein C deficiency associated with cerebral infarction and obstruction of deep leg and inferior mesenteric veins.

Protein C, a vitamin K-dependent protein, is a blood coagulation inhibitor. Its deficiency causes systemic thrombosis. A 31-year-old woman developed cerebral infarction followed by late psychomotor seizures, and thrombosis in the inferior mesenteric vein and bilateral crural veins. Her parents were first cousins. Her mother died of cerebral thrombosis in her 30's. Her elder brother died of suspected purpura fulminans immediately after birth. Her protein C activity and protein C antigen level decreased markedly and were less than 5% of those of normal controls and 0.3 microgram/ml, respectively. Her father, a paternal aunt and a maternal uncle also showed a low protein C activity and protein C antigen level. This patient seems to have congenital protein C deficiency which produced thrombosis in the leg veins and the mesenteric vein, probably cerebral infarction.

Adult↗
PubMed2003

Superior mesenteric vein thrombosis after colectomy for inflammatory bowel disease: a not uncommon cause of postoperative acute abdominal pain.

PURPOSE: Thromboembolism is a significant cause of morbidity and mortality in inflammatory bowel disease. Several prothrombotic conditions have been investigated in inflammatory bowel disease. The aim of this study was to evaluate the incidence of symptomatic postoperative superior mesenteric vein thrombosis in inflammatory bowel disease patients undergoing colonic resections and to identify and characterize their clinical presentation. METHODS: Between January 1999 and December 2001, 83 consecutive patients undergoing total colectomy for inflammatory bowel disease were studied retrospectively. Patients who developed new-onset postoperative acute abdominal pain were evaluated by CT scan of the abdomen. A complete coagulation profile, including thrombin time, platelet count, protein C, protein S, antithrombin III, homocysteine level, factor V Leiden mutation, plasminogen, and prothrombin G20210A mutation, was obtained in patients diagnosed with superior mesenteric vein thrombosis. RESULTS: Four patients (4.8 percent; 3 females; 3 patients with ulcerative colitis and 1 with Crohn's colitis) developed symptomatic postoperative superior mesenteric vein thrombosis. Two of these patients had extension of the clot into the portal vein. Their presenting symptom was abdominal pain, with a median interval of ten days from the index surgery. The hematologic workup was negative in three patients, with one heterozygous for prothrombin G20210A mutation. All patients were treated with systemic anticoagulation for at least six months. One ulcerative colitis patient was diagnosed after abdominal colectomy and underwent an uneventful ileal pouch-anal anastomosis after systemic anticoagulation. CONCLUSION: Postoperative superior mesenteric vein thrombosis is a more frequent occurrence than previously reported in patients with inflammatory bowel disease. Direct surgical trauma to the middle colic veins, with resulting thrombosis, is likely to be the precipitating factor in a borderline intrinsically hypercoagulable environment. All patients became asymptomatic after systemic anticoagulation and recovered uneventfully.

Abdomen, Acute↗
PubMed1967

The innervation of sheep mesenteric veins.

1. An isolated preparation of sheep mesenteric vein is described from which contractions of the longitudinal smooth muscle of the adventitia have been recorded in response to stimulation of intramural and periarterial nerves.2. The preparation did not respond to single stimuli but the relation between amplitude of response and frequency of stimulation was characteristic of that described for other smooth muscles innervated by sympathetic nerves.3. Responses were blocked by tetrodotoxin, guanethidine, and by a number of alpha-receptor blocking drugs. Responses to peri-arterial stimulation were unaffected by hexamethonium. It was concluded that the longitudinal smooth muscle is supplied with post-ganglionic noradrenergic motor nerves and the presence of such fibres in the adventitia was confirmed by fluorescence microscopy.4. Acetylcholine also caused contractions. Although a direct excitatory action on the smooth muscle could not be excluded, results suggest that acetylcholine may release noradrenaline from the axons of the sympathetic ground plexus.

Acetylcholine↗