Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands.

OBJECTIVE: The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR). METHODS: This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests. RESULTS: The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively). CONCLUSION: In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

In Vivo Evaluation of Customized Aortic Repair Using a Novel Survival Model.

OBJECTIVE: The aim of the study was to evaluate the feasibility and mid-term biological behavior of the novel customized aortic repair (CAR) method for endovascular aneurysm treatment. METHODS: CAR consists of exclusion of an aneurysm from the circulation using a custom-designed dog bone-shaped balloon, followed by aneurysm sac filling with an in situ curing polymer. After curing and balloon deflation, the circulation is restored through a patent cast neolumen. A liquid two-component polymer was injected via a small bore catheter under X-ray control into a surgically created aneurysm. In 50% of the procedures, a self expanding bare metal stent was placed in the polymer cast lumen. A novel animal model was established involving creation of an aneurysm by anastomosing a venous interposition graft into the common carotid artery of eight adult sheep. Two animals were excluded because of non-device related complications. The remaining six animals were monitored for 20 weeks with duplex sonograms performed monthly to assess blood flow and polymer cast lumen patency. After the animals were sacrificed the polymer cast, common carotid artery, and the brain in the carotid outflow tract were removed for histological assessment. RESULTS: In four of the six animals, the aneurysm was successfully excluded using CAR with uneventful follow up. The aneurysm sac was filled incompletely in two animals, resulting in a stent malpositioning and cast lumen occlusion after 12 weeks in one case, and a type 1 endoleak in the other. All six animals survived for 20 weeks. Neither migration nor expansion of the polymer cast was observed and the polymer was demonstrated to be biocompatible and non-thrombogenic. Polymer emboli were not detected in the brain or meninges after sacrifice. CONCLUSIONS: The feasibility and mid-term biological safety of the CAR method for minimally invasive aneurysm repair was demonstrated using a simulated aneurysm survival model.

Aortic Customize: an in vivo feasibility study of a percutaneous technique for the repair of aortic aneurysms using injectable elastomer.

OBJECTIVE: This study aimed to test a percutaneous technique for aneurysm-sac filling by means of in situ polymerisation in an in vivo model. DESIGN: Aortic Customize is a new endovascular treatment concept for aortic aneurysms: a non-cross-linked liquid elastomer is injected to fill the aneurysm sac around a balloon-catheter. With this method, a compliant elastomer mould with a patent lumen is created. MATERIAL: The formulation used in the experiments consisted of a two-component addition-cure liquid-silicone formulation, based on vinyl-terminated polydimethylsiloxane (PDMS). METHODS: The concept of aneurysm-sac filling was tested in vivo in porcine experiments (n = 3). RESULTS: In vivo porcine experiments with the sac-filling application showed successful exclusion of the created aneurysms with patent lumens and absence of endoleaks. The aneurysms were excluded successfully in the in vivo model, injecting elastomer through a 7-French catheter, filling up the entire aneurysm sac. CONCLUSIONS: These in vivo experiments demonstrate that the principle of aneurysm-sac filling by means of in situ curing is feasible, excluding the aneurysm and creating a new lumen. Further long-term animal experiments must be done prior to consideration of clinical application.

Donor pretreatment-mediated and cold storage-dependent proximal tubular necrosis--a unique form of acute renal insufficiency.

After a 5-hour period of donor pretreatment with cyclophosphamide (CY) and methylprednisolone (P) (100 mg/kg each), cold storage of pretreated canine renal allografts may cause early and severe postoperative renal insufficiency. This renal insufficiency is mediated by CY metabolites and depends on the number of hours of cold storage, for severe renal insufficiency is not observed after 6 hours of cold storage but is invariably present after cold storage beyond 18 hours. The renal insufficiency is associated with coagulation necrosis of the proximal tubules, particularly the pars recta. Since the repair of ischemia-medicated proximal tubular lesions requires mitotic activity, results suggest that the proximal tubules of donor pretreated kidneys are subjected to a concentration of CY metabolites sufficient to cause an extent of DNA damage that, in the absence of a sufficient time for nuclear repair, inevitably leads to cell death and renal insufficiency when the tubular cells are driven to mitosis by cold storage-mediated ischemia.

Endoluminal pulse oximetry in ischemic colon in a swine model.

BACKGROUND: Postoperative sigmoidal ischemia after aortic grafting is a severe complication. No simple methods are available to detect this entity at an early stage. This study was done to monitor for sigmoidal ischemia with a new endoluminal probe based on pulse oximetry (SmO2). STUDY DESIGN: A prospective controlled animal study was done. Five pigs with low flow in the caudal mesenteric artery (20 percent of the basal flow) and four pigs in a control group were included. General and local circulatory parameters were monitored in the carotid and pulmonary artery and in the caudal mesenteric vein (CMV). Mucosal biopsy specimens were taken for histologic examination. Statistical analysis was done with the Wilcoxon and Mann-Whitney rank sum test and with analysis of variance. RESULTS: During the first two hours of ischemia, no sigmoidal pulse was detected. During the third hour, in three pigs the pulse curve reappeared with a SmO2 of 48 to 88 percent. After two hours, the mean oxygen saturation in the CMV of the ischemic group was 64 percent (compared with the control group, 77 percent, p < 0.05). After one hour, the mean lactate concentrations were 2.0 and 1.3 mmol per L, respectively (p < 0.05). Significant histologic changes occurred with neutrophilic infiltration in the crypts, in the lamina propria, and in the submucosa. CONCLUSIONS: Low-flow sigmoidal ischemia can be detected and monitored with endoluminal pulse oximetry in this model of early sigmoidal ischemia.

Local colonic blood pressure degree through aortic reconstruction procedures: a porcine model.

Sigmoideal ischemia after aortic grafting is a severe complication with high morbidity and mortality. To investigate the basics of this circulatory problem an animal model was created with sigmoideal ischemia that could be quantified. For this purpose a new pig model was developed with stable general circulatory and ventilatory parameters for several hours, while at the same time controlled sigmoideal ischemia was induced. In five pigs a left retroperitoneal approach to the aorta was performed to isolate the caudal mesenteric artery (CMA). Sigmoideal ischemia was achieved by ligating the collateral circulation and constricting the distal aorta. A flow probe was applied to the CMA. An intravascular saturation probe was introduced in the caudal mesenteric vein (CMV) and a pulse oximeter was applied to the serosal surface of the sigmoid. Every hour, blood gas analyses from the carotic artery, CMA, and CMV were completed. Registrations of all circulatory and ventilatory parameters were performed with the help of a computer. The mean flow in the CMA was 29 mL/min (13-45) and decreased to 5 mL/min (3-7) after aortic constriction. Parameters reflecting the stability of the model, such as the cardiac index (mean 89 mL/min kg-1), the mixed venous oxygen saturation (mean 67%), and the total body oxygen consumption (mean 3.3 mL/min kg-1), did not change with statistical significance during 4 h of partial aortic constriction. The conclusion is that a new model has been developed of quantitative sigmoideal ischemia in the pig that was stable for several hours.

Mycotic aneurysm after aortic bifurcation prosthesis.

Fever in the presence of an intravascular graft will focus the clinical investigation on an infection of this graft. This case report describes an uncommon cause of fever in a 75-year-old patient, namely a mycotic aneurysm of the aortic stump.

Submuscular emphysema as a result of diverticulitis of the sigmoid colon without clinical implication.

Diverticulitis of the colon may be the cause of the formation of subcutaneous or submuscular air in the hip or leg region. This phenomenon results mostly in an inflammation or abscess. A case is presented in which sigmoid diverticulitis caused submuscular air without any clinical discomfort.

Hyperparathyroidism due to primary cystic parathyroid adenoma.

Three cases of parathyroid cyst are reported, bringing the total of reported functional and nonfunctional parathyroid cysts to 157 cases. Based on our findings a cystic parathyroid adenoma should be defined as a macroscopic cyst with a diameter larger than 1 cm. The three reported cases of functional parathyroid cysts suggest that they are not as rare as reported. Parathyroid cyst should be considered in every patient with a palpable neck mass, certainly in patients with hyperparathyroidism and a fluid-filled lesion at sonography. Functional parathyroid cysts may be multiple, therefore all four parathyroid glands should be identified, as during exploration for hyperparathyroidism. Our three cases show a preference for the inferior site which is in agreement with the literature. Nonfunctional, generally solitary, parathyroid cysts can be cured by percutaneous aspiration.

Preliminary experience with a new ultraviolet-cured expandable plastic endoprosthesis in the management of malignant esophageal strictures.

BACKGROUND AND STUDY AIMS: Different types of expandable metal stent are currently available for the palliative treatment of malignant esophageal strictures. To overcome some of the disadvantages involved in the design of metal mesh stents, we designed a balloon-expanded plastic endoprosthesis, which is hardened by irradiation with ultraviolet light after deployment. We present here our preliminary results. PATIENTS AND METHODS: From April 1995 to January 1996, four patients with unresectable esophageal malignancies were treated with this stent. Insertion of the stent was the only palliative procedure carried out. The patients were followed up until death. RESULTS: Stent placement was successful in all patients, and no procedure-related complications occurred. Dysphagia was reduced from an average score of 2.6 to 1.0. Early complications included retrosternal pain of limited duration in one patient. One patient died 72 hours after uncomplicated stent placement, due to cardiac arrhythmia. Late complications were limited to tumor overgrowth in two patients, after a mean of 104 days. The stent patency rate averaged 92 days. CONCLUSIONS: In patients with a malignant esophageal stricture, this newly developed expandable endoprosthesis is effective in relieving dysphagia. The deployment of the stent is easy and safe. The endoprosthesis has potential advantage over current expandable metal mesh stents.

Prolongation of canine allograft survival with donor pretreatment.

Donor pretreatment of 100 mg/kg each of cyclophosphamide (CY) and methylprednisolone (P) infused 5 hours before nephrectomy invariably prolongs the survival of DLA mismatched, MLC incompatible nonlittermate Beagle renal allografts as well as the survival of mongrel renal allografts. The effect of donor pretreatment appears to be mediated by cyclophosphamide and its metabolites because methylprednisolone pretreatment does not significantly prolong survival. Methylprednisolone is needed, however, because it abolishes cyclophosphamide pretreatment mediated early but transient postoperative renal (allograft) insufficiency. The effect of donor pretreatment appears to be mediated by drugs residing in the graft; mannitol infusions given 1 hour prior to donor nephrectomy or peroperatively into the recipient decrease the renal cortical content of carbon 14 cyclophosphamide and its metabolites and abolishes the prolonged survival. Because donor pretreated kidneys contain less than 0.5% of the infused dose of carbon 14 cyclophosphamide, the drugs appear to exert their effect locally in the transplanted kidney. Donor pretreatment mediating prolonged canine renal allograft survival appears to be an example of influencing a biological process by a localized drug delivery by virtue of unique properties of the drug and because early postoperatively host sensitization occurs mainly at the site of the graft.

Endoluminal pulse oximetry of the sigmoid colon and the monitoring of the colonic circulation.

Colonic ischaemia is a frequently observed serious complication following abdominal aortic reconstruction. For adequate treatment of this disorder, early diagnosis and resection of the diseased colon is essential. The purpose of this study was to evaluate a new method, based on pulse oximetry, to detect colonic ischaemia at an early preclinical stage. During a 7-year period (1989-1995) colonoscopy and pulse oximetry were performed in all patients at risk of colonic ischaemia: complicated acute or elective aortic reconstructions, colostomies with superficial necrosis and in patients who underwent uncomplicated aortic reconstruction and non-ischaemic colonic problems (n = 90). The sensitivity, specificity and positive predictive values, and negative predictive value, were calculated. All patients, except four for whom an acute relaparotomy was necessary, subsequently underwent colonoscopy combined with endoluminal pulse oximetry. Of the 90 patients, 30 had colonic ischaemia according to endoscopy (n = 26) or relaparotomy (n = 4), and in 33 patients the absence of pulsatile signal was detected by means of pulse oximetry. Thus, in three patients, pulse oximetry was falsely positive for colonic ischaemia. The calculated sensitivity and specificity of pulse oximetry were 100 and 95%, respectively. In comparison to other methods used for early detection of colonic ischaemia, pulse oximetry appears to be a promising method for the evaluation and monitoring of colonic ischaemia because it is non-invasive and easy to apply with a high sensitivity and specificity.

The effect of inhibition of renin-angiotensin system by valsartan during hypovolemic shock and low flow sigmoideal ischaemia in pigs.

The aim of this experiment was to study the effect of Renin-Angiotensin System (RAS) blockade by means of valsartan on the colonic and systemic circulation in pigs during low flow sigmoideal ischemia in combination with hypovolemic shock. This condition resembles the situation that occurs in patients suffering from a ruptured aneurysm and a compromised colonic circulation. An experimental study in pigs was performed : 6 pigs with low flow sigmoideal ischemia and hypovolemic shock were treated with valsartan and a control group of 5 pigs with low flow sigmoideal ischemia and hypovolemic shock without medical treatment.Valsartan, 3 mg/kg, was administered intravenously. The operation was performed via left sided lumbotomy. The distal aorta was partially occluded to a flow reduction of 30% of the initial value. Hypovolemic shock was induced by withdrawing 20 ml/kg blood in 45 min. Resuscitation with 30 ml/kg haemaccel was iniated after 2 h of shock. The following parameters were measured: blood pressure, cardiac output; hemoglobin, lactate, angiotensin II in mixed venous blood (obtained from pulmonary artery) and in splanchnic blood (obtained from caudal mesenteric vein); and endoluminal pulse oximetry of the sigmoideal mucosa. Statistical analysis was performed by ANOVA and Wilcoxon signed rank test. There was a significant increase of lactate levels both in systemic and splanchnic circulation (P<0.05) in both groups. In the control group, the mean angiotensin II concentrations in the systemic circulation increased, after induction of ischaemia and shock. In the experimental group, the increase in angiotensin concentrations after resuscitation was significantly more prominent. In the colonic circulation, in both groups, there was a significant increase in angiotensin II levels in the splanchnic circulation following ischaemia and reperfusion (P<0.05), but there was no significant difference between the groups. There were no detectable mucosal signals measured by pulse oximetry after induction of shock throughout the experiment, whereas in the experimental group, median mucosal oxygen saturations of 81, 74.5 and 85% were achieved after resuscitation and declamping (P<0.01).In conclusion, angiotensin II inhibition during hypovolemic shock improves the colonic circulation, measured by pulse oximetry. However, other parameters of tissue ischaemia did not improve.

Endoluminal pulse oximetry combined with tonometry to monitor the perfusion of the sigmoid during and after resection of abdominal aortic aneurysm.

Early detection of colonic ischaemia after aortic grafting is essential if mortality is to be decreased when this complication develops. The aim of this study was to determine changes in the sigmoid colon during and after abdominal aortic grafting using endoluminal pulse oximetry (SmO2). Oxygen saturation was measured on the mucosa (SmO2) and serosa (SsO2) of 20 sequential patients undergoing elective surgery for abdominal aortic aneurysm; intramural pHi was also measured. Initially, all patients had a normal SmO2 in the sigmoid; however, before cross-clamping eight patients had a reduction in the SmO2. The pulse curve disappeared immediately after cross-clamping in 15 patients, with only five still showing a pulse curve in the sigmoid colon. Before declamping, 13 patients regained their pulse curve. The intraluminal pHi showed a large interindividual variation (2 S.D. approximately 0.4). Patients were classified into three groups according to SmO2: group A, no pulse; group B, diminished saturation (< 90%); and group C, normal saturation (> or = 90%). There was significant correlation with the pHi after cross-clamping in all groups. One patient who developed ischaemia of the sigmoid colon demonstrated a prolonged reduction in the SmO2, a decreased perioperative pHi, and an increased oxygen saturation in the inferior mesenteric vein during cross-clamping.

Sigmoidal ischaemia after aortic grafting, detected by endoluminal pulse oximetry.

Colonic ischaemia after abdominal aortic grafting is a severe complication. Late detection of transmural ischaemia will result in a high mortality rate. No simple specific methods are available to detect the early stage. The aim of this pilot study was to detect and monitor sigmoidal ischaemia after aortic surgery with a new endoluminal sigmoidal probe, based on pulse oximetry. Twelve patients with sigmoidal ischaemia were included, the endoluminal probe being introduced into the sigmoid at least 25 cm proximal to the anal verge. It is shown that with this method, mucosal and transmural ischaemia can be graded and differentiated. Patients who showed no wave-form had transmural ischaemia; those with mucosal ischaemia showed reliable wave-forms with oxygen saturation from 40-85%. Colonic ischaemia after aortic grafting can be detected by endoluminal pulse oximetry but the clinical outcome will only improve by early detection in the preclinical stage.

The renin-angiotensin system in swine during hypovolaemic shock combined with low-flow ischaemia of the sigmoid colon.

Colonic ischaemia is a serious complication after aortic surgery, and is most frequent after repair of ruptured aortic aneurysms. It was felt that the increased risk of colonic ischaemia during shock might be the result of a local effect of the renin-angiotensin system in the splanchnic circulation, which is exacerbated by poor perfusion. In order to evaluate the activity of the renin-angiotensin system in the colonic circulation, a subtotal occlusion of the distal aorta was induced in nine pigs. A colonic flow reduction of 70% was created for 4 hours. In the experimental group (n = 6), induce hypovolaemic shock, 20 cm3/kg blood was sampled at 45 min before resuscitation was performed with 20 cm3/kg haemaccel. The sham group (n = 3) did not have hypovolaemic shock induced. Blood samples were taken for determinations of angiotensin II, haemoglobin and lactate. Blood gas was obtained from the pulmonary artery and the caudal mesenteric vein for blood gas analysis and lactate determinations. ANOVA and the Wilcoxon sum rank test were used for statistical analysis. There was a significant increase in angiotensin II after induction of ischaemia in both groups. The increase in angiotensin II in the splanchnic circulation was more prominent than the increase in the systemic circulation (P < 0.01). In the experimental group, there was a sustained increase in angiotensin II levels in the splanchnic circulation following shock and reperfusion (P < 0/01). The increase in lactate concentrations, which was significantly higher in the experimental group (P < 0.05), was evidence of intestinal ischaemia. There was a significant decline in cardiac output and blood pressure during the period of shock (P < 0.05). The combination of colonic ischaemia and hypovolaemic shock followed by reperfusion leads to an increase in angiotensin II activity. The increase of the local activity of the renin-angiotensin system in the splanchnic circulation is more prominent after ischaemia and reperfusion. This is probably caused by a selective response of the splanchnic vasculature to shock, ischaemia and reperfusion.