[Indications and techniques for endovascular revascularization of visceral arteries in mesenteric ischemia]

Endovascular revascularization of visceral arteries is an important cornerstone of an interdisciplinary treatment concept for both acute and chronic forms of mesenteric ischemia. The advantages lie in the minimally invasive procedure and the speed of restoration of perfusion. This article provides an overview of the indications, techniques and current state of the clinical literature with respect to endovascular revascularization.

The pig is a better model than the rabbit or rat for studying the pathophysiology of human mesenteric arteries

AIMS

Animal models are essential to investigate cardiovascular pathophysiology and pharmacology, but phylogenetic diversity makes it necessary to identify the model with vasculature most similar to that of humans.

METHODS AND RESULTS

In this study, we compared the mesenteric arteries of humans, pigs, rabbits and rats in terms of the i) evolutionary changes in the amino acid sequences of α₁ and β2 adrenoceptors; M₁, M₂, and M₃ muscarinic receptors; and bradykinin (BKR) and thromboxane-prostanoid (TP) receptors, through bioinformatics tools; ii) expression of α₁, β₂, M1, M3 and TP receptors in each tunica, as assessed by immunofluorescence; and iii) reactivity to receptor-dependent and independent contractile agonists and relaxants, by performing organ bath assays. Phylogenetically, pigs showed the highest degree of evolutionary closeness to humans for all receptors, and with the exception of BKR, rabbits presented the greatest evolutionary difference compared to humans, pigs and rats. The expression of the measured receptors in the three vascular tunica in pigs was most similar to that in humans. Using a one-way ANOVA to determine the differences in vascular reactivity, we found that the reactivity of pigs was the most similar to that of humans in terms of sensitivity (pD2) and maximum effect of vascular reactivity (Emax) to KCl, phenylephrine, isoproterenol and carbachol.

CONCLUSIONS

The pig is a better vascular model than the rabbit or rat to extrapolate results to human mesenteric arteries. Comparative vascular studies have implications for understanding the evolutionary history of different species.

TRANSLATIONAL PERSPECTIVE

The presented findings are useful for identifying an animal model with a vasculature that is similar to that of humans. This information is important to extrapolate, with greater precision, the findings in arterial pathophysiology or pharmacology from animal models to the healthy or diseased human being.

Dapagliflozin induces vasodilation in resistance-size mesenteric arteries by stimulating smooth muscle cell KV7 ion channels

Dapagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor that, in addition to glucose reduction, lowers systemic blood pressure. Here, we investigated if dapagliflozin could directly relax small mesenteric arteries that control peripheral vascular resistance and blood pressure, and the underlying molecular mechanism. We used pressurized arterial myography, pharmacological inhibition and Western blotting to investigate the direct effect of dapagliflozin on the contractility of freshly isolated, resistance-size rat mesenteric arteries. Our pressure myography data unveiled that dapagliflozin relaxed small mesenteric arteries in a concentration-dependent manner. Non-selective inhibition of K_V channels and selective inhibition of smooth muscle cell voltage-gated K⁺ channels K_V7 attenuated dapagliflozin-induced vasorelaxation. Inhibition of other major K_V isoforms such as K_V1.3, K_V1.5 channels as well as large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels, ATP-sensitive (K_ATP) channels did not abolish vasodilation. Dapagliflozin-evoked vasodilation remained unaltered by pharmacological inhibition of endothelium-derived nitric oxide (NO) signaling, prostacyclin (PGI₂), as well as by endothelium denudation. Our Western blotting data revealed that SGLT2 protein is expressed in rat mesenteric arteries. However, non-selective inhibition of SGLTs did not induce vasodilation, demonstrating that the vasodilatory action is independent of SGLT2 inhibition. Overall, our data suggests that dapagliflozin directly and selectively stimulates arterial smooth muscle cells K_V7 channels, leading to vasodilation in resistance-size mesenteric arteries. These findings are significant as it uncovers for the first time a direct vasodilatory action of dapagliflozin in resistance mesenteric arteries, which may lower systemic blood pressure.

A primer for measuring cGMP signaling and cGMP-mediated vascular relaxation

Soluble guanylyl cyclase (sGC, also called GC1) is the main receptor for nitric oxide (NO) that catalyzes the production of the second messenger molecule, 3'5' cyclic guanosine monophosphate (cGMP) leading to vasorelaxation, and inhibition of leukocyte recruitment and platelet aggregation. Enhancing cGMP levels, through sGC agonism or inhibition of cGMP breakdown via phosphodiesterase inhibition, has yielded FDA approval for several cGMP modifier therapies for treatment of cardiovascular and pulmonary diseases. While basic research continues to improve our understanding of cGMP signaling and as new therapies evolve to elevate cGMP levels, we provide a short methodological primer for measuring cGMP and cGMP-mediated vascular relaxation for investigators.

Abdominal apoplexy due to rupture of inferior pancreaticoduodenal artery: A rare case of acute abdomen

Background

Abdominal apoplexy is one of the rare causes of non-traumatic intra-abdominal bleeding. This condition is usually seen in male patients in their 50s with history of hypertension. As soon as abdominal apoplexy is suspected, immediate resuscitation should be performed followed by emergent surgery. The patient's outcome depends entirely on the clinical condition and the time interval between diagnosis and treatment.

Case Presentation

Herein we present a 63-year-old man with idiopathic spontaneous intraperitoneal hemorrhage (ISIH) caused by spontaneous rupture of non-aneurysmal inferior pancreaticoduodenalartery (IPDA).

Conclusion

In this report, a case of abdominal apoplexy has been presented caused by spontaneous rupture of non-aneurysmal inferior pancreaticoduodenalartery (IPDA) in a patient without any significant past medical history.

Vascular assessment in small bowel obstruction: can CT predict requirement for surgical intervention?

PURPOSE

Small bowel obstruction (SBO) is a common cause of emergency presentations for abdominal pain and can be complicated by mesenteric ischemia. Computed tomography is currently central to diagnosis and management planning. Currently accepted signs identify secondary effects of the root physiological insult, which is vascular obstruction. We hypothesized that with advancements in CT technology and reconstruction algorithms, we can now more closely interrogate the mesenteric vasculature for obstruction and more accurately predict the need for surgical intervention.

METHODS

We retrospectively audited the charts of all patients presenting with a clinical diagnosis of SBO at a single institution in a 12-month period. Two blinded consultant radiologists were then asked to analyze 3D MIP reconstruction CT scans for vascular obstruction in addition to any currently accepted signs of ischemia. Comparison between vascular cutoff and accepted current signs in the need for surgical intervention and the presence of any signs of ischemia in theater were recorded.

RESULTS

Vascular cutoff had a comparable, with a trend towards superiority, sensitivity and specificity and inter-observer agreement to currently accepted signs of ischemia. The absence of a cut off sign has an excellent negative predictive value for ischemia with only 2 (3.7%) patients demonstrating ischemia at surgery where the vascular cutoff sign was not seen to be present.

CONCLUSION

Interrogating vascular obstruction using 3D MIP reconstructions in small bowel obstruction may be a more sensitive and specific sign for prediction of surgical intervention, possibly occurring earlier in the obstruction pathway.

Mesenteric artery calcium scoring: a potential screening method for chronic mesenteric ischemia

Objective

A practical screening tool for chronic mesenteric ischemia (CMI) could facilitate early recognition and reduce undertreatment and diagnostic delay. This study explored the ability to discriminate CMI from non-CMI patients with a mesenteric artery calcium score (MACS).

Methods

This retrospective study included CTAs of consecutive patients with suspected CMI in a tertiary referral center between April 2016 and October 2019. A custom-built software module, using the Agatston definition, was developed and used to calculate the MACS for the celiac artery (CA), superior mesenteric artery (SMA), and inferior mesenteric artery. Scoring was performed by two blinded observers. Interobserver agreement was determined using 39 CTAs scored independently by both observers. CMI was defined as sustained symptom improvement after treatment. Non-CMI patients were patients not diagnosed with CMI after a diagnostic workup and patients not responding to treatment.

Results

The MACS was obtained in 184 patients, 49 CMI and 135 non-CMI. Interobserver agreement was excellent (intraclass correlation coefficient 0.910). The MACS of all mesenteric arteries was significantly higher in CMI patients than in non-CMI patients. ROC analysis of the combined MACS of CA + SMA showed an acceptable AUC (0.767), high sensitivity (87.8%), and high NPV (92.1%), when using a ≥ 29.7 CA + SMA MACS cutoff. Comparison of two CTAs, obtained in the same patient at different points in time with different scan and reconstruction parameters, was performed in 29 patients and revealed significant differences in MACSs.

Conclusion

MACS seems a promising screening method for CMI, but correction for scan and reconstruction parameters is warranted.

Key Points

• A mesenteric artery calcium score obtained in celiac artery and superior mesenteric artery has a high negative predictive value for chronic mesenteric ischemia and could serve as a screening tool.

• Interobserver agreement of the mesenteric artery calcium score is excellent.

• Scan and reconstruction parameters influence the mesenteric artery calcium score and warrant the development of a method to correct for these parameters.

Distance measurements and origin levels of the coeliac trunk, superior mesenteric artery, and inferior mesenteric artery by multiple-detector computed tomography angiography

The aim of this study is to determine vertebral levels of the coeliac trunk, the superior mesenteric artery, and the inferior mesenteric artery originated from the abdominal aorta and to calculate the distance measurements between these arteries and between these arteries and the aortic bifurcation by multidetector computed tomography angiography technique. It was determined that the nine different vertebral levels of the coeliac trunk, the nine different vertebral levels of the superior mesenteric artery, and the eleven different vertebral levels of the inferior mesenteric artery. The distance measurements between the coeliac trunk and the superior mesenteric artery, the inferior mesenteric artery, the aortic bifurcation were found significant between female and male. In this study, it was determined more different levels than the levels described in classical anatomy. The preoperative information of these morphological variations can contribute to the reduction of surgical time and perioperative vascular complications especially for anterior lumbar interbody fusion and defining the location of the primary lymphatic drainage site for gastrointestinal malignancies.

Finerenone Reduces Intrinsic Arterial Stiffness in Munich Wistar Frömter Rats, a Genetic Model of Chronic Kidney Disease

BACKGROUND

Development of albuminuria and arterial stiffness in Munich Wistar Frömter (MWF) rats, a model of chronic kidney disease, is related to alterations in extracellular matrix, increased oxidative stress, and endothelial dysfunction. Finerenone (FIN), a novel, nonsteroidal, potent, and selective mineralocorticoid receptor antagonist, improves endothelial dysfunction through enhancing nitric oxide (NO) bioavailability and decreasing superoxide anion levels due to an upregulation in vascular and renal superoxide dismutase activity. We hypothesize that FIN reduces arterial stiffness in this model associated to the reduction in albuminuria and matrix metalloproteinase (MMP)-2/9 activity.

METHODS

Twelve-week-old MWF rats with established albuminuria and age-matched normoalbuminuric Wistar (W) rats were treated with FIN (10 mg/kg/day, once-daily oral gavage) or with vehicle (control, C) for 4 weeks.

RESULTS

Arterial stiffness was significantly higher in mesenteric arteries (MA) of MWF-C as compared to W-C. FIN treatment significantly lowered β-index, a measure of intrinsic stiffness independent of geometry, in MWF (βMWF-FIN = 7.7 ± 0.4 vs. βMWF-C = 9.2 ± 0.5, p < 0.05) positively correlating with urinary albumin excretion. Elastin fenestrae area in the internal elastic lamina of MA from MWF-FIN was significantly larger (+377%, p < 0.05). FIN increased plasma pro-MMP-2 and decreased plasma MMP-2 and MMP-9 activities, correlating with reductions in β-index. MA from MWF-FIN exhibited higher NO bioavailability and reduced superoxide anion levels compared to MWF-C.

CONCLUSION

FIN treatment reduces intrinsic arterial stiffness in MA from MWF rats associated with changes in elastin organization, normalization of MMP-2 and MMP-9 activities, and reduction of oxidative stress. Moreover, reduction of arterial stiffness correlates with reduction in albuminuria.

and its vasodilation effects on isolated rat mesenteric arteries

Gerbera piloselloides (L.) Cass. (Compositae) possesses various biological effects. It is used as an oriental remedy for relieving cough and resolving phlegm. The present study is to investigate the vasodilation effects of Gerbera piloselloides on isolated rat mesenteric arteries (MAs) and the potential mechanism. Different organic extracts of Gerbera piloselloides were tested, and an HPLC-UV-FD-based analytical method was established to identify the active constituents. The principal components, namely, 8-MOP (8-methoxypsoralan) and 8-MSD (8-methoxysmyrindiol), were found to be predominant in the extracts of petroleum ether and dichloroform, which showed stronger vasodilation activities. 8-MSD was isolated from Gerbera piloselloides by silica gel column chromatography coupled with a Waters 2545 high throughput autopurification system, and its vasodilation effects were explored by an assay of tension on rat MA rings. The results suggest that 8-MSD induces vascular relaxation in rat MAs via an endothelium-dependent mechanism involving the Kir channel, which enables Ca²⁺ entry in the cell and activates production of NO. The present research indicates that 8-MSD may be therapeutically useful as an anti-hypertension agent and to potentially treat cardiovascular and gastrointestinal diseases.

Impact of moderate- and high-intensity exercise on the endothelial ultrastructure and function in mesenteric arteries from hypertensive rats

Oxidative stress (OS) influences vascular function and structure in spontaneously hypertensive rats (SHRs). It is also responsible for the decreased nitric oxide (NO) bioavailability that influences endothelial vasodilation. The effects of high-intensity exercise on endothelial function and ultrastructure in hypertension remain unknown. Thus, this study investigated the effects of moderate- and high-intensity exercise on hypertension-associated endothelial dysfunction and ultrastructural remodeling. Moderate-intensity (SHR-M) and high-intensity (SHRH) aerobic exercise training groups were compared in age-matched sedentary SHRs (SHRC) and normotensive Wistar-Kyoto rats (WKY-C). The results showed that the endothelial ultrastructure was impaired in the SHR-H and SHR-C groups. Glutathione peroxidase levels were significantly increased in the SHR-M group compared to the SHR-C group. MDA content was higher in the SHR-H group than in the SHR-C group, but the levels of antioxidant enzymes did not increase accordingly. Apocynin scavenging reactive oxygen species (ROS) ameliorated endothelium-dependent vasodilator function in the SHR-H group. However, the SHR-M and WKY-C groups abolished the increased vasodilation induced by apocynin. L-NAME, a NO synthase inhibitor, was applied to isolated mesenteric arteries (MAs) to evaluate NO contribution. Moderate-intensity exercise reversed the decreased NO contribution to MAs in hypertension, and high-intensity exercise aggravated this change. These data suggest that moderate-intensity exercise ameliorated adverse remodeling of the endothelial ultrastructure and function in hypertension by decreasing oxidative stress and increasing NO contribution. However, high-intensity exercise exacerbated all of these changes by increasing OS and ROS contribution, and decreasing NO contribution.

Equilin displays similar endothelium-independent vasodilator potential to 17β-estradiol regardless of lower potential to inhibit calcium entry

Conjugated equine estrogens (CEE) have been widely used by women who seek to relieve symptoms of menopause. Despite evidence describing protective effects against risk factors for cardiovascular diseases by naturally occurring estrogens, little is known about the vascular effects of equilin, one of the main components of CEE and not physiologically present in women. In this regard, the present study aims to compare the vascular effects of equilin in an experimental model of hypertension with those induced by 17β-estradiol. Resistance mesenteric arteries from female spontaneously hypertensive rats (SHR) were used for recording isometric tension in a small vessel myograph. As effectively as 17β-estradiol, equilin evoked a concentration-dependent relaxation in mesenteric arteries from female SHRs contracted with KCl, U46619, PDBu or ET-1. Equilin-induced vasodilation does not involve classical estrogen receptor activation, since the estrogen receptor antagonist (ICI 182,780) failed to inhibit relaxation in U46619-precontracted mesenteric arteries. Vasorelaxation was not affected by either endothelium removal or by inhibiting the release or action of endothelium-derived factors. Incubation with L-NAME (NOS inhibitor), ODQ (guanylyl cyclase inhibitor) or KT5823 (inhibitor of protein kinase G) did not affect equilin-induced relaxation. Similarly, indomethacin (COX inhibitor) or blockage of potassium channels with tetraethylammonium, glibenclamide, 4-aminopyridine, or ouabain did not affect equilin-induced relaxation. Inhibitors of adenylyl cyclase SQ22536 or protein kinase A (KT5720) also had no effects on equilin-induced relaxation. While 17β-estradiol inhibited calcium (Ca²⁺) -induced contractions in high-K⁺ depolarization medium in a concentration-dependent manner, equilin induced a slight rightward-shift in the contractile responses to Ca²⁺. Comparable pattern of responses were observed in the concentration-response curves to (S)-(-)-Bay K 8644, a L-type Ca²⁺ channel activator. Equilin was unable to block the transitory contraction produced by caffeine-induced Ca²⁺ release from intracellular stores. In conclusion, equilin blocks L-type Ca²⁺ channels less effectively than 17β-estradiol. Despite its lower effectiveness, equilin equally relaxes resistance mesenteric arteries by blocking Ca²⁺ entry on smooth muscle.

Neuronal nitric oxide synthase contributes to the normalization of blood pressure in medicated hypertensive patients

Neuronal nitric oxide synthase (nNOS) is expressed in the cardiovascular system and besides NO, generates H₂O₂. nNOS has been proposed to contribute to the control of blood pressure in healthy humans. The aim of this study was to verify the hypothesis that nNOS can contribute to the control of vascular relaxation and blood pressure in hypertensive patients undergoing drug treatment. The study was conducted in resistance mesenteric arteries from 63 individuals, as follows: 1) normotensive patients; 2) controlled hypertensive patients (patients on antihypertensive treatment with blood pressure normalized); 3) uncontrolled hypertensive patients (patients on antihypertensive treatment that remained hypertensive). Only mesenteric arteries from uncontrolled hypertensive patients showed impaired endothelium-dependent vasorelaxation in response to acetylcholine (ACh). Selective nNOS blockade with inhibitor 1 and catalase, which decomposes H₂O₂, decreased vasorelaxation in the three groups. However, the inhibitory effect was greater in controlled hypertensive patients. Decreased eNOS expression was detected in both uncontrolled and controlled hypertensive groups. Interestingly nNOS expression and ACh-stimulated H₂O₂ production were greater in controlled hypertensive patients, than in the other groups. ACh-stimulated NO production was lower in controlled hypertensive when compared to normotensive patients, while uncontrolled hypertensive patients showed the lowest levels. Catalase and nNOS blockade inhibited ACh-induced H₂O₂ production. In conclusion, nNOS-derived H₂O₂ contributes to the endothelium-dependent vascular relaxation in human resistance mesenteric arteries. The endothelial dysfunction observed in uncontrolled hypertensive patients involves decreased eNOS expression and NO production. The normalization of vascular relaxation and blood pressure in controlled hypertensive patients involves increased nNOS-derived H₂O₂ and NO production.

One visceral artery may be enough; successful pancreatectomy in a patient with total occlusion of the celiac and superior mesenteric arteries

Background

The anatomic variations of the visceral arteries are not uncommon. The liver arterial blood supply shows 50% variability between humans, with the most common anatomy being one hepatic artery arising from the celiac trunk and one pancreatico-duodenal arcade between the celiac trunk and the superior mesenteric artery. Occlusion of one artery are mostly asymptomatic but may become clinically relevant when surgery of the liver, bile duct or the pancreas is required. If these pathologies are not reversible, an oncologic pancreatic head resection cannot be performed.

Case presentation

We report the case of a 64-year-old Caucasian female patient with a locally advanced, resectable adenocarcinoma of the pancreas with complete atherosclerotic occlusion of the celiac trunk and the superior mesenteric artery. This vascular anomaly was missed on the preoperative imaging and became known postoperatively. A collateral circulation from a hypertrophic inferior mesenteric artery to the celiac trunk and the superior mesenteric artery compensated the blood supply to the visceral organs. The postoperative course was complicated by an elevation of the transaminases AST/ALT, which normalized under conservative treatment with alprostadil (prostavasin™) and anticoagulation, since angiographic recanalization failed. The patient recovered fully and was discharged at the 14th postoperative day. Two years later, she required endovascular repair of an aortic rupture during which the inferior mesenteric artery was preserved.

Conclusion

This case underlines the natural potential of the human body to adapt to chronic arterial malperfusion by creating a collateral circulation and supports the need for adequate preoperative imaging, including a proper arterial phase before upper abdominal surgery.

SKA-31, an activator of endothelial Ca2+-activated K+ channels evokes robust vasodilation in rat mesenteric arteries

It is now well recognized that endothelial KCa2.3 and KCa3.1 channel activities contribute to dilation of resistance arteries via endothelium-mediated hyperpolarization and vascular smooth muscle relaxation. In this study, we have investigated the functional effect of the KCa channel activator SKA-31 in third order rat mesenteric arteries using arterial pressure myography. Isolated arteries were cannulated, pressurized intraluminally to 70 mmHg at 36 °C and then constricted with 1 μM phenylephrine. Acute bath exposure to SKA-31 evoked a robust and reversible inhibition of developed tone (IC₅₀ = 0.22 μM). The vasodilatory effects of SKA-31 and acetylcholine were blunted in the presence of KCa2.3 and KCa3.1 channel antagonists, and were largely prevented following endothelial denudation. Western blot and q-PCR analyses of isolated mesenteric arteries revealed KCa2.3 and KCa3.1 channel expression at the protein and mRNA levels, respectively. Penitrem-A, an inhibitor of KCa1.1 channels, decreased vasodilatory responses to acetylcholine, sodium nitroprusside and NS-1619, but had little effect on SKA-31. Similarly, bath exposure to the eNOS inhibitor L-NAME did not alter SKA-31 and acetylcholine-mediated vasodilation. Collectively, these data highlight the major cellular mechanisms by which the endothelial KCa channel activator SKA-31 inhibits agonist-evoked vasoconstriction in rat small mesenteric arteries.

Binding and functional pharmacological characteristics of gepant-type antagonists in rat brain and mesenteric arteries

AIM

The neuropeptide calcitonin gene-related peptide (CGRP) is found in afferent sensory nerve fibers innervating the resistance arteries and plays a pivotal role in a number of neurovascular diseases such as migraine and subarachnoid bleedings. The present study investigates the binding and antagonistic characteristics of small non-peptide CGRP receptor antagonists (i.e. gepants) in isolated rat brain and mesenteric resistance arteries.

METHODS

The antagonistic behavior of gepants was investigated in isolated rat mesenteric arteries using a wire myograph setup while binding of gepants to CGRP receptors was investigated in rat brain membranes using a radioligand competitive binding assay. Furthermore, the histological location of the key components of CGRP receptor (RAMP1 and CLR) was assessed by immunohistochemistry.

RESULTS

Our functional studies clearly show that all gepants are reversible competitive antagonists producing Schild plot slopes not significantly different from unity and thus suggesting presence of a uniform CGRP receptor population in the arteries. A uniform receptor population was also confirmed by radioligand competitive binding studies showing similar affinities for the gepants in rat brain and mesenteric arteries, the exception being rimegepant which had 50-fold lower affinity in brain than mesenteric arteries. CLR and RAMP1 were shown to be located in both vascular smooth muscle and endothelial cells of rat mesenteric arteries by immunohistochemistry.

CONCLUSION

The present results indicate that, despite species differences in the CGRP receptor affinity, the antagonistic nature of these gepants, the distribution pattern of CGRP receptor components and the mechanism behind CGRP-induced vasodilation seem to be similar in resistance-sized arteries of human and rats.

Vascular imaging of the mesenteric vasculature

Imaging of the mesenteric vasculature is crucial in diagnosing vascular disease of the gastro-intestinal tract such as acute or chronic mesenteric ischemia caused by arterial stenosis, embolism or thrombosis, mesenteric vein thrombosis and mesenteric aneurysm or dissection. The reference standard for imaging of the mesenteric vasculature is digital subtraction angiography. However, modalities as duplex ultrasonography, computed tomography angiography and magnetic resonance angiography are developing rapidly and may provide accurate imaging non-invasively. This review provides an up-to-date overview of the anatomic resolution, clinical application, emerging techniques and future perspectives of these four radiological modalities for imaging of the mesenteric vasculature.

Intensive Long Distance Running as a Possible Cause of Multiple Splanchnic Arterial Aneurysms: A Case Report

This is a case report that suggests the possible association between multiple splanchnic arterial aneurysms and long-distance running. The clinical features of one patient admitted at Chungbuk National University Hospital for treatment of multiple splanchnic arterial aneurysms were reviewed. A 54-year-old man had a recurrent, intermittent and epigastric pain for 2 months. There was no abnormality in gastroscopy and colonoscopy. An abdominal computed tomography angiography documented calcified superior mesenteric artery (SMA) and splenic artery aneurysms. The patient had a history of recreational long-distance running for over 10 years. His average running time per week was more than 10 hours. There was no evidence of systemic arteritis, connective tissue disorder or infectious process that may have caused the aneurysms. He did not take any drugs. The SMA aneurysm was opened, and the aneurysmal segment of SMA was replaced with a vein graft. The splenic aneurysm was observed. The patient recovered without any sequelae.

Colectomy in patients with previous colectomy or occlusive vascular diseases: Pitfalls and precautions

Two principal branches from the aorta provide the colonic blood supply: the superior and inferior mesenteric arteries. There are numerous anatomical variations, which the surgeon must fully understand before embarking on any colonic surgery. A good knowledge of these variations is particularly important when the patient has already undergone colectomy or presents with occlusive vascular disease. The aim of this review is to summarize the standard anatomy and the main variations of the colonic blood supply as they apply to colorectal surgery in this setting.

The vasodilatory action of telmisartan on isolated mesenteric artery rings from rats

OBJECTIVES

Angiotensin II type 1 receptor blockers (ARBs) represent one of the widely used antihypertensive agents. In addition to anti-hypertension effect, some ARBs also show other molecular effects such as activating peroxisome proliferator-activated receptor-γ and so on. Here we studied the effects of telmisartan on the rat isolated mesenteric artery rings pre-contracted by phenylephrine (PE).

MATERIALS AND METHODS

Rat mesenteric artery rings were pre-contracted with 10 μM PE, and cumulative concentration-response curves to telmisartan were obtained. The endothelium-dependent mechanisms were investigated by mechanical removal of the endothelium. K(+) channels were investigated by pretreatment of the artery rings with various K(+) channel blockers.

RESULTS

Telmisartan produced concentration-dependent relaxation of the artery rings pre-contracted by 10 μM PE. Denudation of the endothelium did not affect the relaxant effect of telmisartan. Pretreatment with BaCl2 nearly inhibited the relaxation induced by the 0.5, 1, 5 and 10 μM telmisartan, but did not affect the relaxation induced by the 50 and 100 μM telmisartan. While the relaxation induced by telmisartan was not affected by pretreatment with TEA, 4-AP and glibenclamide.

CONCLUSION

These findings demonstrated that telmisartan produces concentration dependent vasodilation in isolated rat mesenteric artery rings with or without endothelium pre-contracted by PE. KIR channel may be involved in such a relaxant effect of telmisartan.

Multiple visceral artery aneurysms managed by Yasargil aneurysm clips

Here, we present the case of a 37-year-old woman with multiple visceral artery aneurysms in the pancreaticoduodenal, inferior pancreatic and splenic arteries associated with celiac trunk stenosis. An aneurysmectomy and end-to-end anastomosis was performed for two adjacent aneurysms, while clipping with intracranial aneurysm clips were performed for the other three aneurysms. During 36-month follow-up, no recurrence or newly developed lesions were noted, and the celiac artery had been reconstituted spontaneously. We believe that using intracranial aneurysm clips in the treatment of visceral artery aneurysms is feasible and safe and can be considered when endovascular procedures are unlikely to be successful.

Factors influencing the yield of mesenteric angiography in lower gastrointestinal bleed

AIM: To assess if certain triaging rules could be established to optimize the yield of mesenteric angiography.

METHODS: Medical records of 101 patients were retrospectively reviewed and parameters relating to age, gender, pulse rate, blood pressure, serum hemoglobin, intensive care unit (ICU) admission, and the number of packed red blood cells (PRBC) transfused in the 12 and 24 h prior to the angiography were tabulated in two groups with positive and negative angiography results.

RESULTS: We found no correlation between gender, pulse rate, blood pressure or serum hemoglobin and positivity of the mesenteric angiogram. But patients with positive angiogram were found to be on average 7 years older (73.2 years vs 65.9 years old) (P = 0.02). Angiogram was positive in 39.3 % (11/28) of patients admitted in ICU vs 23.2% (17/73) who were admitted elsewhere in the hospital (P = 0.03). In the 12 and 24 h prior to angiography, patients with a positive angiogram received a mean of 2.7 ± 2.3 and 3.3 ± 2.6 units of PRBC s respectively, while patients with a negative angiogram had a mean of 1.6 ± 1.9 (P = 0.02) and 2.1 ± 2.6 units (P = 0.04) received respectively in the same period.

CONCLUSION: Older age, ICU admission, having received at least 4 units PRBC over 12 h or 5 units over 24 h prior to angiogram are leading indicators for a positive study.

Impaired effect of relaxin on vasoconstrictor reactivity in spontaneous hypertensive rats

Relaxin is thought to be involved in vasodilation to pregnancy by increasing endothelium-dependent vasodilation and compliance, and decreasing myogenic reactivity. Primary (essential) hypertension predisposes to circulatory maladaptation and subsequent gestational hypertensive disease. This study aimed to determine that vascular responses to chronic exposure to relaxin are impaired in young female rats with primary hypertension. In 10-12 weeks old Wistar-Hannover rats (WHR) and spontaneous hypertensive rats (SHR), we determined vascular responses in isolated kidney and mesenteric arteries after 5-days of chronic exposure to relaxin (4 μg/h) or placebo. SHR show decreased sensitivity to phenylephrine (by 67%, p<0.01) and renal perfusion flow (RPFF, by 19%, p<0.01), but no changes in flow-mediated vasodilation, myogenic reactivity or vascular compliance. In WHR, relaxin stimulated flow-mediated vasodilation (2.67 fold, from 48 ± 9 to 18 ± 4 μl/min, p = 0.001), inhibited myogenic reactivity (from -1 ± 2 to 7 ± 3 μm/10 mmHg, p = 0.01), and decreased sensitivity to phenylephrine (28%, from 1.39 ± 0.08 to 1.78 ± 0.10 μM, p<0.01), but left compliance and RPFF unchanged. NO-blockade by L-NAME diminished most relaxin-mediated responses. In SHR, the vasodilator effects of relaxin were blunted for myogenic reactivity and sensitivity to phenylephrine, with similar effects on flow-mediated vasodilation, compliance, RPFF and equal Rxfp1 (relaxin family peptide receptor) gene expression, as compared to WHR. Primary hypertension blunts both the relaxin-induced inhibition of myogenic reactivity and α-adrenergic vasoconstrictor response, independent from Rxfp1 gene expression, while the relaxin-dependent enhanced flow-mediated vasodilation remains intact. This implies selective resistance to relaxin in young subjects suffering from primary hypertension.

Aberrant celio-mesenteric supply of the splenic flexure: Provoking a bleed

Lower gastrointestinal hemorrhage presents a common indication for hospitalization and account for over 300000 admissions per year in the United States. Multimodality imaging is often required to aid in localization of the hemorrhage prior to therapeutic intervention if endoscopic treatment fails. Imaging includes computer tomography angiography, red blood cell tagged scintigraphy and conventional angiography, with scintigraphy being the most sensitive followed by computer tomography angiography. Aberrant celio-mesenteric supply occurs in 2% of the population; however failure to identify this may result in failed endovascular therapy. Computer tomography angiography is sensitive for arterial hemorrhage and delineates the anatomy, allowing the treating physician to plan an endovascular approach. If at the time of conventional angiography, the active bleed is not visualized, but the site of bleeding has been identified on computer tomography angiography, provocative angiography can be utilized in order to stimulate bleeding and subsequent targeted treatment. We describe a case of lower gastrointestinal hemorrhage at the splenic flexure supplied by a celio-mesenteric branch in a patient and provocative angiography with tissue plasminogen activator utilized at the time of treatment to illicit the site of hemorrhage and subsequent treatment.

Structure and function of cerebral and mesenteric resistance arteries in low-dose endotoxin-infused pregnant rats

OBJECTIVE

Since the cerebrovasculature likely plays a prominent role in the pathophysiology of eclampsia, we assessed the effects of low-dose endotoxin-induced experimental preeclampsia on the function and structure of rat posterior cerebral arteries (PCA) and mesenteric arteries (MA).

METHODS

Nonpregnant (NP) and pregnant (P) rats were infused with saline (NP-CTL, n=9; P-CTL, n=9) or low-dose endotoxin (NP-endotoxin, n=9; P-endotoxin, n=10). Myogenic activity, pressure of forced dilatation (FD) and structural properties were evaluated in PCA and MA.

RESULTS

PCA underwent FD between 125 and 150mmHg in P-endotoxin (repeated measures ANOVA vs 75mmHg; P<0.05) and between 150 and 175mmHg in P-CTL and NP animals (repeated measures ANOVA vs 75mmHg; P<0.05). PCA myogenic tone was unaffected by pregnancy or endotoxin, however, pregnancy decreased the MA myogenic tone (P<0.05 vs NP). Passive characteristics of PCA and MA were unaffected by pregnancy or endotoxin.

CONCLUSION

Low-dose endotoxin-infusion during pregnancy, but not pregnancy alone, decreased the pressure of FD in PCA. This may predispose to cerebral autoregulatory breakthrough and edema formation during increased blood pressure as seen in eclampsia.

Gender difference and change of α(1)-adrenoceptors in the distal mesenteric arteries of streptozotocin-induced diabetic rats

BACKGROUND

The purpose of this study was to evaluate the gender-related changes in the function and distribution of α(1)-adrenoceptors in the distal mesenteric artery of streptozotocin (STZ)-induced diabetic rats at the level of α(1)-adrenoceptor subtypes.

METHODS

Diabetes was induced by intravenous injection of STZ in a dose of 60 mg/kg through the tail vein in 8 week-old male or female Sprague-Dawley rats (n = 13/group). Age-matched normal rats (n = 15) were used as a control group. Four weeks after STZ injection, the change in mean arterial pressure caused by a 45° tilting was recorded. The α(1)-adrenoceptor subtypes mediating contractions of the distal mesenteric artery were investigated using the agonist, phenylephrine as well as subtype-selective antagonists including prazocin, 5-methylurapidil, and BMY 7378. The expression of α(1)-adrenoceptor subtypes of each artery was examined by immunofluorescence staining and western blotting using subtype selective antibodies.

RESULTS

Compared with normal male rats, the contractile response to phenylephrine was decreased in the distal mesenteric artery in normal female rats. Moreover, a decrease in contractile force was observed in STZ-induced diabetic rats compared with age-matched controls. Western blotting revealed that there was the difference between normal male and female rats in manifestation of the α(1D)-adrenoceptor. In STZ-induced male and female diabetic rats, all α(1)-adrenoceptor subtypes were decreased in distal mesenteric arteries, compared with normal rats.

CONCLUSIONS

There was the gender-related functional difference of α(1)-adrenoceptors in normal rats. In both male and female rats, diabetes decreased the contractile response in mesenteric arteries, which might be caused by the overall change in α(1)-adrenoceptor.