Spontaneous Anastomosis Research Articles

Hierarchical Vessel Network-Supported Tumor Model-on-a-Chip Constructed by Induced Spontaneous Anastomosis.

The vascular system in living tissues is a highly organized system that consists of vessels with various diameters for nutrient delivery and waste transport. In recent years, many vessel construction methods have been developed for building vascularized on-chip tissue models. These methods usually focused on constructing vessels at a single scale. In this work, a method that can build a hierarchical and perfusable vessel networks was developed. By providing flow stimuli and proper HUVEC concentration, spontaneous anastomosis between endothelialized lumens and the self-assembled capillary network was induced; thus, a perfusable network containing vessels at different scales was achieved. With this simple method, an in vivo-like hierarchical vessel-supported tumor model was prepared and its application in anticancer drug testing was demonstrated. The tumor growth rate was predicted by combining computational fluid dynamics simulation and a tumor growth mathematical model to understand the vessel perfusability effect on tumor growth rate in the hierarchical vessel network. Compared to the tumor model without capillary vessels, the hierarchical vessel-supported tumor shows a significantly higher growth rate and drug delivery efficiency.

Preoperative evaluation of moyamoya spontaneous anastomosis of combined revascularization donor vessels in adults by duplex ultrasonography

Objective: To evaluate the preoperative diagnostic value of duplex ultrasonography in moyamoya spontaneous anastomosis of combined revascularization donor vessels in adults.Methods: A total of 99 preoperative adult patients who underwent superficial temporal artery-to-middle cerebral artery (STA-MCA) anastomosis were retrospectively analyzed. Each side of the cerebral hemisphere was examined as a separate procedure. A total of 198 cerebral hemispheres were divided into three groups: a collateral, non-collateral, and control group based on digital subtraction angiography (DSA). Hemodynamic parameters, including peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were analyzed.Results: There were only four of cases (5%, 4/198) of STA spontaneous anastomosis, whereas those of maxillary artery (MA) anastomosis were 44 (23.7%, 44/186). Compared with the control group, MA PSV and EDV of the collateral group increased significantly, while RI decreased significantly (p < .05). The area under the curve (AUC) of MA RI was 0.654. As a predictor of MA spontaneous anastomosis, duplex ultrasonography had high specificity but poor sensitivity. In collateral group, PSV and EDV detected two weeks post-surgery were significantly higher than those detected pre-operatively (PSV: p = .018, EDV: p = .025). By contrast, there were no significant difference of the PSV and EDV detected six months post-surgery compared with pre-operation (PSV: p = .450, EDV: p = .099). Additionally, MA RI in two weeks after the surgery was comparable with preoperative values.Conclusions: Duplex ultrasonography could be applied to evaluate the adult moyamoya spontaneous anastomoses of MA preoperatively. Despite its poor sensitivity, this diagnostic modality is still reliable and specific. STA-MCA anastomosis combined with EDMS did not affect MA pre-operative spontaneous anastomosis.

Indirect revascularization for nonmoyamoya intracranial arterial stenoses: clinical and angiographic outcomes

Symptomatic intracranial arterial stenoses have a high rate of recurrent stroke despite medical and endovascular treatments. The authors present clinical and angiographic quantitative outcomes of indirect revascularization for patients with symptomatic intracranial stenosis. Patients treated for symptomatic intracranial arterial stenosis by indirect revascularization were included. The patient population comprised those in whom medical management had failed and for whom endovascular therapy was unsuitable or had failed. Patients underwent encephaloduroarteriosynangiosis (EDAS) with or without bur holes. Preoperative and postoperative angiograms were evaluated for change in caliber of extracranial blood vessels (superficial temporal artery [STA] and middle meningeal artery [MMA]) and for evidence of neovascularization. Thirteen patients underwent EDAS. Ischemic symptoms ceased within the follow-up period in all patients, returning in a delayed fashion in only 2. No other patients had recurrent TIAs or strokes after the initial postoperative period. Donor blood vessels increased in size relative to preoperative sizes in all but 1 case (average increase of 52% for proximal STA [p=0.01], 74% for midpoint of STA [p=0.01], and 84% for the MMA [p=0.02]). In addition, 8 of 11 patients demonstrated direct spontaneous anastomoses from extracranial to middle cerebral artery branches, and all patients demonstrated angiographic evidence of vascular blush and/or new branches from the STA and/or MMA. Indirect revascularization appears to be a safe and effective method to improve blood flow to ischemic brain due to intracranial arterial stenosis. Neovascularization and enlargement of the branches of the ECA were observed in all patients and correlated with improvement in ischemic symptoms. Indirect revascularization is an option for patients in whom medical therapy has failed and who are not suitable for endovascular treatment.

Reversed arterial flow in the paramedian segments of the liver after pancreaticoduodenectomy

Variation of splanchnic arterial anatomy is frequent and may complicate pancreatic surgery, leading to life-threatening postoperative complications. We report a case of severe hepatic dysfunction after pancreaticoduodenectomy due to accidental section of the right hepatic artery. Bedside ultrasound examination showed a reversed arterial flow in the paramedian segments of the liver. Based on intraoperative and ultrasound findings, a retrograde arterial supply of the right liver from the left hepatic artery through spontaneous anastomosis between the arteries of segment 4 and the right paramedian segments was assumed and confirmed by postoperative CT examination.

Use of intraluminal stents in multiple intestinal atresia

Multiple intestinal atresia presents a difficult technical problem because of extreme loss of intestinal length, disparity of residual bowel wall size, and discontinuity of multiple short intestinal segments. The authors report on a 3,000-g infant with gastroschisis complicated by intrauterine volvulus and multiple intestinal atresias who was treated successfully with intraluminal stenting and sutureless anastomoses. A total of 25 cm of small bowel was salvaged including 13 segments each measuring 1 to 8 cm in length. Subsequent radiographic studies showed spontaneous anastomosis with a compartmental configuration of the residual bowel and decreased transit time. Five months postoperatively, the patient was weaned off total parenteral nutrition completely and one year later is growing and gaining weight with 4 to 6 bowel movements per day. J Pediatr Surg 37:34. Copyright 2002, Elsevier Science (USA). All rights reserved.

Pelvic inflammatory disease after tubal sterilization: a review.

Exceptions ot the common notion that tubal occlusion protects from recurrent pelvic inflammatory disease (PID) do exist. Since 1975, 71 cases of salpingitis and 38 tubo-ovarian abscesses (TOA) in sterilized women have been published. The majority of cases of salpingitis after previous tubal occlusion (SPOT) developed more than a year after either laparoscopic or laparotomy sterilization procedures. For tubo-ovarian abscess after previous tubal occlusion (TOAPOT), this time interval ranged from several weeks to almost two decades. Most cases of salpingitis showed inflammation of both tubal segments. When only one segment was involved, it was generally the proximal segment. The appearance of the TOAPOT at the time of surgery was typical to TOA. The symptoms of salpingitis were not different from symptoms in any other case of PID, and those associated with TOAPOT were typical of TOA. Laboratory findings included leucocytosis and growth of Neisseria gonorrohoea and Chlamydia trachomatis from the cervix, the infected tube, and the peritoneal fluid. Pus cultures obtained from cases of TOAPOT grew mixed or single organisms. Detailed histopathologic studies in tubal specimens after the failure of an occlusion procedure are available from cases with no infection. They have demonstrated distortion, loss of musculature, and loss of lumen configuration, all of which may have been the result of compromised blood supply to the tube. These findings may be extrapolated to cases of SPOT and TOAPOT, assuming similar changes may be present before the development of infection. The mechanisms by which infection may develop in previously occluded tubes are divided into three groups: The first group consists of situations where there is persistence of free passage between the proximal and distal portions of the tube. These include toboperitoneal fistula, spontaneous anastomosis at the occlusion site, recanalization of the occluded site, incomplete tubal occlusion due to a faulty surgical technique or rupture of the weakened tubal wall. The second group consists of infections initiated by the surgical procedure itself, such as introduction of pathogens at surgery, exacerbation of chronic PID, and ascending infection secondary to surgical manipulation. In the third group, the infection is initiated systemically by hematogeneous spread, lymphatic spread, or change in immunologic status.

もやもや病に対する穿頭術を組み合わせた吻合術

The branches of external carotid artery were separately used to revascularize all areas supplied by ACA, MCA and PCA. The parietal branch of STA was usually used for an end to side anastomosis with a cortical branch of MCA. EDAS, using the proximal part of the frontal branch of STA, and EMS, using the inner layer of temporal muscle, were also performed in all pateints to stimulate spontaneous anastomosis. In addition, frontal burr holes were made to induce vascularization of the ACA areas from the distal part of frontal branch of ACA. If necessary, occipital burr holes in the area supplied by occipital artery was also added for the PCA territories. The first operation was performed on the dominant side, then a similar procedure was performed on the opposite side after an interval of at least 3 months.Postoperative clinical symptoms improved in most of the cases. The findings from MRI, MRA, angiography, and SPECT demonstrated an improvement of cerebral circulation through operative sites with disappearance of abnormal vessels. Rapid normalization of the EEG occurred within a year in more than half of the pateints.These results suggest that the placement of frontal and occipital burr holes, in addition to STA-MCA anastomosis, EDAS, and EMS, is effective in vascularizing the ischemic areas in patients with moyamoya disease.

Anatomy of spontaneous splenorenal and gastrorenal venous anastomoses: Review of the literature

Anatomy of spontaneous splenorenal and gastrorenal venous anastomoses: Review of the literature

Anatomy of spontaneous splenorenal and gastrorenal venous anastomoses Review of the literature

Portal hypertension is characterised by the development of a collateral portocaval circulation. Among these venous reroutings, some are situated posteriorly in the left subphrenic compartment. These are the spontaneous splenorenal and gastrorenal anastomoses. Their incidence is estimated at around 16%. On the one hand, there are the direct shunts, which anastomose the spelling v. to the left renal v., of an anecdotal nature, and on the other the spontaneous indirect splenorenal shunts, characterised by the presence of a complete neurovascular pedicle traversing the gastrophrenic ligament. This relates to the gastric collateral v., which is connected to the left renal v. via the inferior v. of the left crus of the diaphragm and the middle capsular v., hence the name "gastro-phreno-capsulo-renal shunt". At an advanced stage of portal hypertension these splenorenal shunts may acquire a major caliber and behave like actual surgical shunts.

Surgical treatment for pediatric moyamoya disease: use of the superficial temporal artery for both areas supplied by the anterior and middle cerebral arteries.

To revascularize ischemic territories of both the anterior cerebral artery (ACA) and the middle cerebral artery (MCA), a simple and effective combined bypass operation was performed in 36 pediatric patients with moyamoya disease during the past 8 years. The branches of the superficial temporal artery (STA) were used to revascularize the ACA and MCA territories. In children older than 5 years, the parietal branch of the STA was usually used for an end to side anastomosis with a cortical branch of the MCA. In children who were younger than 5 years, the parietal branch of the STA was used for an encephaloduroarteriosynangiosis instead of a direct anastomosis. Encephaloduroarteriosynangiosis, using the proximal part of the intact frontal branch of the STA, and encephalomyosynangiosis, using the temporal muscle, were also performed in all patients to stimulate spontaneous anastomosis. In addition, bilateral frontal burr holes were made in all patients to induce vascularization of the ACA territories from the distal part of the intact frontal branch of the STA. The first operation was performed on the dominant side, then a similar procedure was performed on the opposite side after an interval of at least 3 months. Postoperative clinical symptoms and the findings from magnetic resonance imaging, magnetic resonance angiography, angiography, and electroencephalography demonstrated improvement in all patients. These results suggest that the placement of bilateral burr holes (while leaving the frontal branch of the STA intact), in addition to the STA-MCA anastomosis, encephaloduroarteriosynangiosis, and encephalomyosynangiosis, is very effective in vascularizing the ischemic ACA and MCA territories in pediatric patients with moyamoya disease.

Spontaneous Anastomosis of Transected Vessels

Experiments were performed on rats to establish the capacity for spontaneous repair of transected arteries and veins. The tests were done on the femoral vessels, with transection effected in a number of modifications. Veins proved capable of bridging even a triple transection within 2 weeks. Not a single artery, however, anastomosed. Vascular repair was on the basis of adventitial and perivascular networks. Explanations of arterial incapacity for spontaneous repair can presently be only speculative. The observations add to our knowledge concerning the revascularization of free grafts, and also indicate that in veins, spontaneous anastomosis can be induced by loosely approximating the stumps.

Ultrasonographic diagnosis of portal vein cavernous transformation in children.

The aim of this work was to evaluate the efficiency, sensitivity, and specificity of ultrasonographic findings in the diagnosis of portal vein cavernous transformation and secondary splanchnic hypertension in children. Twenty patients with esophageal varices on endoscopic sclerotherapy, with ages ranging from 1 to 15 years (mean of 7.5), were compared with 20 age-matched normal asymptomatic controls. In 17 cases, diagnosis was confirmed by splenoportography. Ultrasonographic portal vein features, respiratory variations in splenic and superior mesenteric veins, lesser omentum to aorta diameter ratio and spleen size, as well as the presence of vessels in the lesser omentum and of spontaneous anastomoses, were analyzed in both groups. The efficiency of ultrasonography to establish a diagnosis of portal vein cavernous transformation reached 100%. Splenic and superior mesenteric vein respiratory variation was negligible in patients and inspiration versus expiration diameter differences ranged from 1 to 4 mm (mean of 2.4) in controls (p less than .001). Mean lesser omentum to aorta ratio was 2.07 in patients versus .9 in controls (p less than .001). Splenomegaly was found in all but two cases; lesser omentum vessels were visualized in nine cases; whereas five presented spontaneous splenorenal anastomoses and gallbladder varices were observed in five patients. Thus, ultrasonography allowed portal vein cavernous transformation to be diagnosed throughout; portal hypertension was also detected. It may be concluded that ultrasonography, either alone or associated with endoscopy, provides a reliable method for portal vein cavernous transformation diagnosis. Angiography should be reserved for preoperative or controlled hemodynamic studies.

The Lurking Sperm: Vasectomy Failures

To the Editor.— My comments are prompted by the article entitled Lurking Sperm: A Review of Failures in 8879 Vasectomies Performed by One Physician by Dr Alderman 1 and Dr Schmidt's 2 editorial. Since 1952,I have performed and followed up over 26 600 vasectomies and have been frequently involved as an expert witness in legal cases involving vasectomies. My procedure is to excise a 3-cm section of each vas. The ends are crushed and tied (five to seven times each) with absorbable suture. I have had only one known failure (spontaneous anastomosis). I stopped using fulguration because as a consultant I was seeing many failures after fulguration among patients of other physicians. I concluded that burned tissue cannot be controlled and is often apt to lead to later patency rather than occlusion of a lumen. Fulguration is not reliable, consistent, predictable, or controllable. The higher risk of death under

Spontaneous anastomosis of vessels approximately 100 μ in diameter: an experimental study

Spontaneous anastomosis of vessels approximately 100 μ in diameter was studied in experiments on rats. The vessels—both arteries and veins—were transected and the stumps joined with a suture. In the veins, a fully functional anastomosis developed within 5 to 7 days after the intervention. Spontaneous anastomosis was, however, relatively uncommon with arteries and also took longer. The experiments support the view that anastomosis is governed by chemotaxis.

Angiographic demonstration of cerebral revascularization after encephalo-duro-arterio-synangiosis (EDAS) performed on pediatric moyamoya patients.

For the treatment of the moyamoya disease, we developed a surgical procedure of Encephalo-duro-aterio-synangiosis (EDAS), which was conducted in 15 cases on 23 sides. As a result we obtained improvement in cerebral vascularization as well as in neurological and electroencephalographic findings in all cases. This report describes an introduction of the procedure and a review of the postoperative cerebral angiograms. Cerebral revascularization by EDAS proceeded on the following steps, and it was confirmed that efficient cerebral revascularization could be obtained 6 months after the operation in almost all cases following the steps: 1) dilatation and increase of dural artery, 2) dilatation of donor scalp artery, 3) cerebral revascularization with the development of visible fine spontaneous anastomoses between the donor scalp artery and the cerebral arteries and 4) further dilatation of the donor scalp artery and retraction of the abnormal rete vasculosum at the base of the brain.

Reanastomosis of the vas deferens.

To the Editor.— Temporary spontaneous reanastomosis of the vas deferens, presented by Marshall and Lyons (219:1753, 1972), is of great interest to all those performing vasectomies. In order for a fistula to develop there must be active changes taking place in the tissues. The normal healing process results in a rather rapid production of granulation tissue followed by regressive changes and scar formation. This process is prolonged by chemical irritation from the suture materials, especially surgical silk. The reaction from absorbable materials is shorter. Completely biologically inert material, such as tantalum, produces no irritant effect, and scar formation is solely due to the ischemia produced by compression of the tissues. According to this hypothesis, late spontaneous anastomosis of the vas ends is more likely to occur with the use of silk ligatures. It also may occur after several months if there has been leakage of sperm from the proximal end

The influence of succinylsulfathiazole (Sulfasuxidine) upon the response of canine small intestine to irradiation

A study was carried out to determine whether the injury attending intense segmental intestinal irradiation could be reduced by diminishing and altering the intestinal bacterial flora. Sulfasuxidine administration for 3 days before and 6 weeks after irradiation of isolated segments of canine ileum with 4000 r significantly reduced the lethality attending the irradiation of 15- cm lengths of ileum and reduced the inflammatory cell infiltration and edema and increased the vascularity of the granulation tissue internally lining the mucosally denuded areas of 5-cm lengths of ileum. Following the rapid complete loss of mucosa attending irradiational injuries of 4000 r, the size of the mucosally denuded area was reduced by exponential longitudinal shortening by the absorption of the irradiated muscle and connective tissue. An almost complete spontaneous anastomosis of proximal and distal nonirradiated intestine was effected 8 months after the irradiation of 5-cm lengths of ileum. The administration of Sulfasuxidine did not influence this rate of absorption. The mechanisms of the obstruction of the irradiated intestines are discussed. (M.C.G.)

Intussusception of ileum with expulsion of intussusceptum per anum

1. 1. A case of intussusception of the ileum with spontaneous anastomosis and spontaneous expulsion per anum of the intussusceptum and recovery is presented. 2. 2. Intussusception is briefly discussed. 3. 3. Reports of similar type cases are reviewed.