Bypass Placement Research Articles

3D Printed Surgical Guide for Coronary Artery Bypass Graft: Workflow from Computed Tomography to Prototype.

Patient-specific three-dimensional (3D) printed models have been increasingly used in many medical fields, including cardiac surgery for which they are used as planning and communication tools. To locate and plan the correct region of interest for the bypass placement during coronary artery bypass graft (CABG) surgery, cardiac surgeons can pre-operatively rely on different medical images. This article aims to present a workflow for the production of a patient-specific 3D-printed surgical guide, from data acquisition and image segmentation to final prototyping. The aim of this surgical guide is to help visualize the region of interest for bypass placement during the operation, through the use of dedicated surgical holes. The results showed the feasibility of this surgical guide in terms of design and fitting to the phantom. Further studies are needed to assess material biocompatibility and technical properties.

Survival and complications in cats treated with subcutaneous ureteral bypass.

To report the complications and factors affecting outcome for cats following placement of a subcutaneous ureteral bypass (SUB™). In this retrospective study, complications, the presence of a urinary tract infection and survival time were recorded following subctutaneous ureteral bypass placement. Factors affecting survival time were assessed using a Kaplan Meier curve and log rank test. Ninety-five cats had 130 subcutaneous ureteral bypasses placed. Ten cats did not survive to discharge. Forty cats died or were euthanised after discharge (42%); the median survival time of these cats was 530 days (range 7 to 1915). Minor complications occurred in 18 cats (19%) and major complications occurred in 46 cats (48%), the majority of which were after hospital discharge. Twenty-seven cats were diagnosed with a urinary tract infection (UTI) post-operatively. A significant association between long-term survival and creatinine at presentation was identified. The median survival time for cats presenting with creatinine concentration ≥440 μmol/L (International Renal Interest Society stage acute kidney injury (AKI) 4 and 5) was 530 days (95% CI 273-787 days), compared to a median survival time of 949 days (95% CI 655-1243 days; Log Rank P=0.024) for those cats presenting with creatinine <440 μmol/L (International Renal Interest Society stage AKI 1-3). In this population of cats, subcutaneous ureteral bypass placement was associated with an approximately 10% in-hospital mortality and a high complication rate. Most complications were manageable, resulting in an overall median survival time of over 2 years.

Longitudinal computational fluid dynamics study of stenosis and aneurysmal degeneration of an aortorenal bypass.

Saphenous vein graft (SVG) bypass placement is regarded as the optimal option for renal artery stenosis, which usually causes secondary hypertension and poor renal perfusion. Using computational fluid dynamics, this study aimed to investigate the underlying hemodynamic mechanism of the vein aneurysm and stenosis after aortorenal bypass surgery. Three-dimensional models were reconstructed based on computed tomographic angiography images of a 20-year-old female patient who suffered from uncontrollable hypertension using the image processing package Mimics (Materialise). The morphology and hemodynamic parameters in the healthy state, at initial presentation and at post-operative 9-month and 2-year follow-ups after surgery were analysed. The hemodynamic parameters became normal in the left and right renal arteries after bypass surgery. However, flow separation and stagnation occurred at the post-operative 9-month aorta-vein anastomosis, which caused asymmetrical flow and extremely high wall shear stress (WSS) and WSS gradients at the outflow vein tract, where the stenosis occurred 2years later. In addition, the graft bending produced an asymmetrical flow pattern downstream. This research revealed that the abnormal hemodynamics, including flow separation and extremely high WSS values and gradients, caused by the retrograde flow of aortorenal bypass may be responsible for the SVG degeneration. In addition, flow asymmetry due to vessel bending is a potential risk factor for SVG aneurysm dilation.

Treatment and outcomes of ureter injuries due to ovariohysterectomy complications in cats and dogs.

To describe the presentation, treatment and outcome of unilateral and bilateral ureter injuries resulting from ovariohysterectomy complications in cats and dogs. Retrospective case series of cats and dogs with ureteric injuries resulting from an ovariohysterectomy complication. Patient signalment, history, presenting clinical signs, clinical pathology, imaging, diagnosis, treatment and outcome were obtained from the medical records and telephone contact with the owners. Fourteen female cats and five female dogs were included. Eleven (58%) exhibited clinical signs immediately after recovery from ovariohysterectomy, six (32%) had a median onset of clinical signs of 3 days (range 1 to 16 days), and two (10%) were referred immediately because of a known complication during surgery. Five of seven animals with bilateral ureter injury presented with anuria. Three animals died or were euthanased without definitive surgery. Surgical repair included ureteroneocystostomy (eight cats, one dog), ureteronephrectomy (four cats, two dogs), subcutaneous ureteral bypass placement (three cats) and ureteral stent (one cat). Of the 16 operated animals, seven (44%) that were discharged from the hospital experienced major complications requiring one or more additional surgeries. Overall outcome was excellent in 13 (68%), good in one (5%), fair in one (5%) and poor in four (22%) animals. A key indicator of a ureteric injury is an animal failing to recover normally or becoming unwell shortly after ovariohysterectomy. Anuria is likely in animals with bilateral ureter injury. Excellent outcomes are possible following surgical treatment.

Diagnostic imaging observations in cats treated with the subcutaneous ureteral bypass system.

To describe pre- and post-operative ultrasonographic and fluoroscopic findings, including any abnormalities, in cats treated for ureteral obstruction with a subcutaneous ureteral bypass system. Retrospective review of imaging findings in cats with ureteral obstruction that had surgery to place the first version of the bypass system and at least one follow-up ultrasound or fluoroscopic study. Pre- and post-operative renal pelvic diameter on ultrasound, fluoroscopic appearance of the bypass system and any related abnormality were recorded. Eighty-one cats were included (47 unilateral, 34 bilateral bypass systems). Median preoperative renal pelvic diameter was 9 mm (range 3 to 28 mm) and median renal pelvic diameter at the first postoperative ultrasound was 3 mm (range 2 to 23 mm). The median number of postoperative imaging studies was two (range 1 to 8) and the median follow-up period after surgery was 205 days (range 1 to 1378 days). Bypass system abnormalities were identified postoperatively in 43 (53%) cats, including nephrostomy or cystostomy catheter blockage due to an undetermined cause or kinking of the catheter, nephrostomy or cystostomy catheter leakage, non-obstructive kinking of the catheter and loose nephrostomy pig-tail loop. Many abnormalities required repeat surgery, but others were managed conservatively. Fifty-four percent of obstructed ureters became patent after bypass placement, although the majority remained slightly dilated or had irregular margins compatible with chronic inflammation. Bypass abnormalities, mainly tube blockage, occurred frequently in cats treated for ureteral obstruction. Ultrasonography and fluoroscopy were useful for postoperative examination, including documenting renewed ureteral patency and investigation of suspected abnormalities.

Temperature Disturbance Management in a Heat Exchanger Network for Maximum Energy Recovery Considering Economic Analysis

The design of heat exchanger networks (HEN) in the process industry has largely focused on minimisation of operating and capital costs using techniques such as pinch analysis or mathematical modelling. Aspects of operability and flexibility, including issues of disturbances affecting downstream processes during the operation of highly integrated HEN, still need development. This work presents a methodology to manage temperature disturbances in a HEN design to achieve maximum heat recovery, considering the impact of supply temperature fluctuations on utility consumption, heat exchanger sizing, bypass placement and economic performance. Key observations have been made and new heuristics are proposed to guide heat exchanger sizing to consider disturbances and bypass placement for cases above and below the HEN pinch point. Application of the methodology on two case studies shows that the impact of supply temperature fluctuations on downstream heat exchangers can be reduced through instant propagation of the disturbances to heaters or coolers. Where possible, the disturbances have been capitalised upon for additional heat recovery using the pinch analysis plus-minus principle as a guide. Results of the case study show that the HEN with maximum HE area yields economic savings of up to 15% per year relative to the HEN with a nominal HE area.

Local cerebral hemodynamics following STA-MCA bypass in patients with symptomatic carotid occlusions

To assess changes in local hemodynamic parameters in patients with symptomatic ICA occlusions and moyamoya disease after placement of extracranial-intracranial bypass (EC-IC bypass). The study included 112 patients who underwent surgical treatment at the National Scientific and Practical Center for Neurosurgery in the period between 1999 and 2015. Of these, 105 patients had ICA occlusions, and 7 patients had moyamoya disease. During the main stage of EC-IC bypass placement, all patients were monitored for local hemodynamic parameters using intraoperative contact Doppler ultrasonography - 89 (72%) patients (72%) and flowmetry - 56 (50%)). In 33 (29%) cases, both techniques were used. Forty two patients underwent preoperative SCT perfusion to assess the degree of perfusion deficit. Grade 1 cerebrovascular insufficiency (acute oligemia) was detected in 6 patients; grade 2 perfusion deficit (persistent oligemia) was found in 25 patients; grade 3 perfusion deficit (chronic oligemia) was present in 11 patients. Measurements were performed before bypass placement: the blood flow direction and hemodynamic parameters in the cortical arteries were evaluated; and after bypass placement: blood flow values and directions in the cortical artery, proximal and distal to the bypass area, were assessed. A total of 112 EC-IC bypasses were placed without perioperative complications and deaths. Bypass functioning was confirmed in 108 (96.3%) cases; bypass thrombosis occurred in 4 (3.7%) cases. The distal blood flow direction was observed in patients with ICA occlusions (105 patients) in all cases before EC-IC bypass placement. Patients with moyamoya disease had more often the proximal blood flow direction - 5 (71%) out of 7 cases. The cerebral blood flow parameters obtained in this study differed significantly, depending on the baseline degree of perfusion deficit. The blood flow rate was minimal in patients with grade 1 cerebrovascular insufficiency. After revascularization, local hemodynamics in the cortical arteries was significantly dependent on the ability of EC-IC bypass to reverse blood flow in the proximal acceptor artery. A change in the blood flow direction was observed in 86 (77%) cases. The mean volumetric blood flow in EC-IC bypass was 34.2±5.7 mL/min. The knowledge of baseline hemodynamic parameters and their changes after revascularization plays an important role in choosing the correct surgical technique, further bypass functioning, and, as a result, improvement of the clinical outcome after surgery.

Urinary Tract Infections after Ureteral Stent or Subcutaneous Ureteral Bypass (SUB) Placement in Three Cats

Urinary Tract Infections after Ureteral Stent or Subcutaneous Ureteral Bypass (SUB) Placement in Three Cats

Risk factors for positive urine cultures in cats with subcutaneous ureteral bypass and ureteral stents (2010-2016).

BackgroundUreteral stent and subcutaneous ureteral bypass (SUB) placement are commonly used for managing ureteral obstructions. Urinary tract infection (UTI) is a recognized complication.ObjectivesTo determine postoperative incidence of positive urine cultures in cats undergoing ureteral stent and SUB placement and to identify risk factors associated with positive urine cultures.DesignRetrospective study.AnimalsForty‐three cats that underwent 48 surgical events.ProceduresMedical records were reviewed. Cats were included if urine cultures were performed before and after surgery. Variables were compared to identify risk factors.ResultsUrine cultures were positive postoperatively pre‐discharge in 5/20 (25%) cats. Median duration of follow‐up post‐discharge was 209 days (range, 11‐2184 days), with a total of 143 urine cultures performed in cats post‐discharge. Of these, 16 (11%) were positive in 12/48 (25%) cats. Nine different bacteria were identified; Enterococcus spp. (n = 8) predominated as monomicrobic or mixed infections. In 14/16 instances of positive urine cultures, affected cats had lower urinary tract signs, signs of pyelonephritis or both. Cats that received antibiotics postoperatively were significantly less likely to have a positive urine culture compared to those that did not (odds ratio, 0.2, 95% confidence interval, 0.05, 0.8, P = 0.02). Chronic kidney disease, renal implant type and postoperative urinary catheterization were not associated with positive urine cultures.Conclusions and Clinical RelevancePostoperatively, occurrence of positive urine cultures was similar to previous reports. Subclinical bacteriuria was less common than UTI. Postoperative urinary catheterization has been speculated to increase risk of bacteriuria, but this was not the case in this cohort.

Transesophageal ultrasonography during orthotopic liver transplantation: Show me more.

The first perioperative transesophageal echocardiography (TEE) guidelines published 21years ago were mainly addressed to cardiac anesthesiologists. TEE has since expanded its role outside this setting and currently represents an invaluable tool to assess chamber sizes, ventricular hypertrophy, and systolic, diastolic, and valvular function in patients undergoing orthotopic liver transplantation (OLT). Right-sided microemboli, right ventricular dysfunction, and patent foramen ovale (PFO) are the most common intra-operative findings described during OLT. However, left ventricular outflow tract obstruction and left ventricular ballooning syndrome are more difficult to recognize and less frequent. Transesophageal ultrasonography (TEU) during OLT is also underused. Its applications are as follows: (1) assistance in the difficult placement of pulmonary arterial catheters; (2) help with catheterization of great vessels for external veno-venous bypass placement; (3) intra-operative evaluation of surgical liver anastomosis patency, if feasible, through the liver window; and (4) intra-operative investigation of "acute hypoxemia" due to pulmonary and cardiac issues using trans-esophageal lung ultrasound (TELU). The aims of this review are as follows: (1) to summarize the uses of TEE and TEU throughout all phases of OLT, and (2) to describe other new feasible applications.

The use of high-flow extracranial-intracranial artery bypass in pathology of the cerebral and brachiocephalic arteries: technical features and surgical outcomes

Poor outcomes of surgical treatment for complex cerebral aneurysms due to the development of cerebral ischemia were the cause to use cerebral revascularization surgery for this pathology. the study objective was to master a high-flow extracranial-intracranial (EC-IC) artery bypass technique and evaluate its application in surgical treatment of complex and giant cerebral aneurysms as well as complex lesions of the brachiocephalic arteries. Fifty two patients underwent high-flow IC-EC bypass surgery; of these, 34 patients had complex cerebral aneurysms, and 18 patients had complex stenotic occlusive lesions of the brachiocephalic arteries. After bypass placement, the patients with aneurysms underwent different variants of aneurysm exclusion (trapping or proximal clipping/ligation of the parent artery). All patients underwent follow-up studies of the bypass function and clinical condition in the early postoperative period and 6 and 12 months after surgery. High-flow IC-EC bypass surgery is routinely used in clinical practice of the Novosibirsk Federal Center of Neurosurgery. Fifty one out of the 52 patients were followed-up in a range of 4 to 56 months. According to the direct or CT angiography data, bypasses functioned in 51 (98.1%) patients in the early and long-term postoperative periods. The clinical efficacy (no ischemic changes and improved cerebral perfusion) of high-flow IC-EC bypasses was demonstrated in 31 (91.2%) of 34 patients with aneurysms and in 17 (94.4%) of 18 patients with complex lesions of the brachiocephalic arteries. The total number of surgical complications was 8 (15.4%) cases: 7 complications occurred in patients with aneurysms, and 1 complication developed in a patient with bilateral ICA occlusion. Of these, ischemic complications developed in 4 (7.7%) cases, hemorrhagic complications occurred in 2 (3.8%) cases, and cranial nerve complications were found in 2 (3.8%) cases. One (1.9%) female patient with a giant aneurysm died from hemispheric stroke due to insufficient blood flow through the bypass. Implementation of a large number of surgeries enabled improvement of the technique and clarification of the prerequisites for preoperative examination, intraoperative control, and postoperative management of patients. A low mortalits rate suggests this technique for use in clinical practice. The surgery is indicated for the treatment of giant aneurysms of the petrous, cavernous, and clinoid segments of the ICA. In the case of giant supraclinoid aneurysms, the surgery may be combined with removal of thrombotic masses from the aneurysm sac for rapid decompression of the cranial nerves. Application of this surgery for treatment of giant aneurysms of the trunk and bifurcation of the basilar artery is promising but requires further investigation. The surgery is also recommended for improving cerebral perfusion in the setting of complex stenotic occlusive lesions of the BCA: prolonged BCA stenoses, tandem ICA stenoses located in both the extracranial and intracranial segments, nonspecific vasculitis and arteriitis, subcranial aneurysms, kinking etc.

A retrospective study of anesthesia for subcutaneous ureteral bypass placement in cats: 27 cases.

The goals of this retrospective clinical case series study were to describe the management of anesthesia, and to report perioperative complications in cats undergoing subcutaneous ureteral bypass (SUB) placement due to ureteral obstruction. Medical records of client-owned cats with ureteral obstruction and anesthetized for SUB placement between 2012 and 2015 in a veterinary teaching hospital were reviewed. Twenty-seven cases were identified. Duration of anesthesia and surgery (mean ± standard deviation) were 215 ± 42 min and 148 ± 36 min, respectively. Hypothermia was the most common intraoperative complication. Hypotension, hypocapnia, hypertension and bradycardia were also frequently observed. Out of 22 cats who experienced intraoperative hypotension, 17 received inotropes and vasopressors. There was a significant decrease in creatinine (P=0.008) and total solids (P=0.007) after SUB placement when compared with baseline values. Postoperative complications included pain, anorexia, nausea, hypertension, and urinary tract-related problems. No death occurred in the postoperative period. Successful management of anesthesia for SUB placement involves rigorous anesthetic monitoring and immediate treatment of complications. Perioperative complications appear to be common. This study could not identify risk factors associated with this procedure.

A global mathematical model for the simulation of stenoses and bypass placement in the human arterial system

This paper is concerned with a global mathematical model for the human circulation; we describe its construction, its validation and its application to study the haemodynamical effect of stenoses and bypass placement in the arterial system. A geometric multiscale approach is adopted combining one-dimensional (1D) descriptions to represent 55 major arteries and zero-dimensional (0D) compartmental descriptions for the heart, lungs, the venous system and the microcirculation. Modern non-linear numerical methods are implemented for solving the 1D systems of hyperbolic partial differential equations and high-order Runge–Kutta methods are used to solve the systems of Ordinary Differential Equations resulting from the compartmental models. The complete global mathematical model is then validated for healthy and stenotic cases comparing numerical predictions from the model against in-vivo measurements. Results show overall satisfactory agreement. In addition, a sensitivity analysis is conducted in order to assess the influence of the most important parameters on some haemodynamical quantities of interest. We then apply the model to simulate the haemodynamics for healthy controls and subjects with arterial stenosis. We study the haemodynamical effect of bypass placement, considering different locations in the arterial system, different degrees of severity, for both single and multiple arterial stenoses. Haemodynamical quantities of interest in the study are local pressure and flow rate. We observe that large stenotic plaques near the heart cause abnormally strong pressure waves in the circulatory system and two adjacent occlusions worsen the phenomenon. We find that the mathematical model is capable of predicting the most convenient bypass location and graft dimensions, consistent with normal haemodynamics.

Methodological framework for economical and controllable design of heat exchanger networks: Steady-state analysis, dynamic simulation, and optimization

The problem of interaction between economic design and control system design of heat exchanger networks (HENs) is addressed in this work. The controllability issues are incorporated in the classical design of HENs. A new methodological framework is proposed to account for both economics and controllability of HENs. Two classical design methods are employed, namely, Pinch and superstructure designs. Controllability measures such as relative gain array (RGA) and singular value decomposition (SVD) are used. The proposed framework also presents a bypass placement strategy for optimal control of the designed network. A case study is used to test the applicability of the framework and to assess both economics and controllability. The results indicate that the superstructure design is more economical and controllable compared to the Pinch design. The controllability of the designed HEN is evaluated using Aspen-HYSYS closed-loop dynamic simulator. In addition, a sensitivity analysis is performed to study the effect of bypass fractions on the total annualized cost and controllability of the designed HEN. The analysis shows that increasing any bypass fraction increases the total annualized cost. However, the trend with the total annualized cost was not observed with respect to the control effort manifested by minimizing the integral of the squared errors (ISE) between the controlled stream temperatures and their targets (set-points). An optimal ISE point is found at a certain bypass fraction, which does not correspond to the minimal total annualized cost. The bypass fractions are validated via open-loop simulation and the additional cooling and/or heating utility requirements, in order to meet the target temperatures, are optimized. The optimum bypass fraction, which minimizes the additional utilities, is found to be the same as the one determined by minimization of ISE.

Early surgical bypass versus endoscopic stent placement in pancreatic cancer.

391 Background: Biliary obstruction frequently occurs in locally advanced or metastatic pancreatic cancer and is often managed by surgical biliary bypass or endoscopic stenting. We compared readmissions/reinterventions among pancreatic cancer patients undergoing bypass vs. stenting. Methods: Retrospective analysis of unresected pancreatic cancer patients in the Healthcare Cost and Utilization Project (HCUP) Florida State Inpatient Database and Florida State Ambulatory Surgery Database 2007-2011 using revisit variables. Patients with early surgical or endoscopic approach analyzed. Subsequent admissions and surgical, endoscopic or percutaneous interventions identified. Propensity score matching by approach. Univariate analysis of patient characteristics and outcomes before and after matching. Multivariate analysis of readmission and reintervention performed by logistic regression. Results: 1,823 and 342 underwent endoscopic treatment vs. early surgical bypass, respectively. After propensity score matching, 684 patients analyzed (table). 64.0% (219) of endoscopic and 70.5% (241) of surgical patients readmitted (p=0.07) and 15.2% (57) and 9.1% (31) underwent reintervention (p=0.01). Endoscopic patients had lower index median length of stay (6 vs 11 days, p&lt;0.01) and admission costs ($11,549 vs $23,215, p&lt;0.01). In multivariate analysis, surgical biliary bypass was predictive of readmission (OR 1.50; 95% CI 1.03-2.18), but initial procedure was not predictive of reintervention (p=0.20). Conclusions: Surgical biliary bypass is less commonly performed than endoscopic stenting. Among propensity score-matched patients, readmission rates are similar, though endoscopic patients require more subsequent interventions. Candidates for both techniques may experience fewer invasive procedures if offered initial surgical biliary bypass. [Table: see text]

17 URETEROCALICOSTOMY FOR THE TREATMENT OF SELECT CASES OF URETEROPELVIC JUNCTION OBSTRUCTION

INTRODUCTION AND OBJECTIVES: Hydronephrosis can be a serious complication of aortic reconstructive surgery, presenting in early or late postoperative period. The incidence and treatment tactics for this infrequent complication are still debated in literature. Our study tries to answer these questions. METHODS: 450 patients following aortofemoral and aortoiliac reconstruction were included. There were 382 (84.9%) males and 68 (15.1%) females with a median age of 65.7 8.3 years. Patients were investigated preoperatively and at 1 week, 3, 6 and 12 months after vascular surgery. Two urologists performed clinical and ultrasound examination, intravenous pyelograms assessment. Patients with preoperatively diagnosed urological pathology were not included into this study. RESULTS: We revealed unilateral hydronephrosis in 8.0% (36/ 450) of patients. 83.3% (30/36) of them had a history of aortic aneurysm resection with aortofemoral bypass grafting and 16.7% (6/36) underwent aortofemoral bypass only (p 0.05). There were 44.4% (16/36) patients with mild obstruction and 55.6% (20/36) patients with extensive ureteral strictures. The mild asymptomatic obstruction resolved spontaneously following 1 month of observation. Patients with late (6–12 months) obstruction developed ureteral strictures and required for active management. They underwent ureterolysis and ureteral resection with ureteroureterostomy. Four of them developed stricture relapse postoperatively. Intraureteral metallic self-expanding endoprosthesis placement was performed to eliminate the obstruction in 3 cases. One patient with obliteration of ureter underwent subcutaneus nephrovesical bypass. CONCLUSIONS: Ureteral obstruction can be a serious complication of reconstructive aortic surgery. This especially concerns to aneurysms of abdominal aorta and patients with graft complications. Early mild asymptomatic obstruction may resolve spontaneously or require ureteral stenting. Late hydronephrosis may contribute to retroperitoneal fibrosis associated with periureteral inflammatory process and extensive ureteral strictures. Intraureteral metallic self-expanding endoprosthesis or subcutaneus nephrovesical bypass placement can be appropriate in patients with contraindications to open reconstructive surgery.

症候性大型‐巨大海綿静脈洞部内頚動脈瘤に対する治療戦略―バイパス術・血管内治療の併用タイミングについて―

For the treatment of symptomatic large-giant aneurysm in the cavernous portion of the internal carotid artery (ICA), it is often necessary to occlude the ICA with or without extracranial-intracranial (EC-IC) bypass surgery. We report 11 patients with such symptomatic lesions treated between January 2004 and June 2008 by staged endovascular trapping of the aneurysm with detachable coils following selective EC-IC bypass placement. The necessity of the bypass was determined according to neurological conditions and radiological findings during the preoperative balloon test occlusion (BTO) of the ICA. When ischemic symptoms occurred during BTO, high-flow bypass was selected. Otherwise, findings on single-photon emission computed tomography were used for the bypass selection. Following completion of the bypass, dual antiplatelet therapy was induced. Then the confirmative BTO and endovascular ICA occlusion (ICA-O) under local anesthesia were planned several days after the bypass placement. A total of 4 high-flow bypasses with radial artery graft were placed before ICA-O, while 7 patients underwent endovascular ICA-O without bypass surgery. There were no perioperative complications related to the procedures in 10 cases, but 1 developed cerebral infarction 7 days after bypass placement possibly due to distal embolism from intraaneurysmal thrombus. No patients showed postoperative symptoms according to insufficient ipsilateral cerebral blood flow, and cranial nerve palsies improved in all patients. Favorable outcomes can be expected for patients with such aneurysms by staged endovascular ICA-O with selective EC-IC bypass. Although endovascular ICA-O can be safe and useful, understanding of adequate antithrombotic therapy and treatment timing are especially important in cases with bypass placement.

Endovascular abdominal aortic aneurysm repair complicated by spondylodiscitis and iliaco-enteral fistula

Infections of abdominal aortic endografts are rare. There are no reports on the association with spondylodiscitis. We report a case of a 74-year-old man who underwent endovascular aneurysm repair (EVAR) and subsequently femorofemoral bypass placement due to occlusion of the right limb of the endograft. Six months later, he presented with rectal bleeding, weight loss, back pain, and low abdominal pain. Computed tomography revealed extensive abscess formation with air in and around the endograft and psoas muscles, in continuity with destructive spondylodiscitis L3-4. There was a small bowel loop in close proximity to the occluded right leg of the endograft, which was filled with air bubbles. An axillofemoral bypass was created followed by a laparotomy. Intra-operatively, an iliaco-enteral fistula was found. The small bowel defect was sutured, the endograft completely removed, and the infrarenal aorta and both common iliac arteries were closed. Necrotic fragments of the former L3-4 disk were removed. The postoperative course was uneventful. Seven months postoperatively, the patient had recovered well. Iliaco-enteric fistula and spondylodiscitis are rare complications of aortic aneurysm repair. This is the first report of spondylodiscitis after EVAR.

Cholangiocarcinoma

Cholangiocarcinoma is a malignant lesion of the bile duct epithelium. Its incidence and prevalence are low. It appears from the sixth decade of life and there is slight male predominance. It is most frequently found in the confluence of the hepatic ducts, where it is called hilar cholangiocarcinoma or Klatskin tumor. Its etiology is unknown but there are predisposing conditions and environmental risk factors such as primary sclerosing cholangitis, Caroli's disease, bile duct malformations, industrial toxins and parasitic infections. The classic presentation of cholangiocarcinoma includes jaundice, weight loss and right upper quadrant pain. These, in addition to laboratory exams, endoscopical and imaging procedures, lead to the diagnosis. Hilar cholangiocarcinoma must be distinguished from other malignant or benign causes of biliary obstruction. Cholangiocarcinoma of the distal common bile duct must be differentiated from other periampullary tumors and intrahepatic cholangiocarcinoma can be confused with a hepatocellular carcinoma. Two classifications are used for clinical staging: TNM and Bismuth-Corlette. The best treatment is the complete surgical excision with negative histological margins, although the resectability index is low. The type and size of surgery depends on the location and extent of the tumor. Patients with unresectable tumors can be subjected to palliative procedures such as biliary-enteric bypass, endoscopic or pecutaneous stent placement. Chemotherapy is not effective. Recently, endoscopic phototherapy has emerged as a better alternative for palliative care.

Duplex Features of Vein Graft Stenosis and the Success of Percutaneous Transluminal Angioplasty

Purpose: To determine if criteria exist that are correlated to a successful outcome after balloon angioplasty for vein graft stenosis. Methods: During a 5-year period, duplex surveillance of 380 infrainguinal vein bypasses identified 76 hemodynamically failing grafts (87 stenoses) requiring intervention. Percutaneous transluminal angioplasty (PTA) was selected over surgical repair based on 3 criteria: time interval from primary grafting procedure, vein graft diameter, and stenosis length. The 28 (32%) stenoses (20 grafts) treated by PTA were used in a retrospective analysis to test if any variables favored a successful outcome. Patient and lesion characteristics, graft patency, and restenosis following PTA were correlated with duplex features of the stenosis recorded prior to, immediately after, and at 3- to 6-month intervals postprocedurally. Results: Lesion characteristics that correlated with a successful outcome were vein size ≥3.5 mm, lesion length &lt; 2 cm, and appearance &gt; 3 months after surgery. Conduit type, PTA site, patient demographics, and indication for bypass did not correlate with PTA durability. Nineteen lesions in 13 grafts met these criteria (group 1), while 9 stenoses in 7 grafts did not (group 2). Lesion severity based on duplex velocity measurements were similar in both groups before (p = 0.40) and after (p = 0.32) treatment. During the mean 21-month follow-up, group 1 grafts required less intervention (p = 0.035). At last follow-up, hemodynamic changes were durable in group 1 (p = 0.0068) but not in group 2 (p = 0.39). Conclusions: Selection of vein graft stenoses for treatment by PTA can be based on temporal and duplex data. PTA of short (&lt; 2 cm) stenoses in good caliber veins (≥ 3.5 mm) appearing &gt; 3 months after bypass placement was durable with a late intervention rate of approximately 10%. Direct surgical repair or replacement is recommended for early (&lt; 3 months) and/or long segment stenoses that develop in small caliber conduits.