Porcine carotid artery replacement with biodegradable electrospun poly-e-caprolactone vascular prosthesis.

OBJECTIVE: There is a continuous search for shelf-ready small-caliber vascular prostheses with satisfactory early and late results. Biodegradable scaffolds, repopulated by recipient's cells regenerating a neovessel, can be a suitable option for adult and pediatric, urgent and elective cardiovascular procedures. METHODS: This was a short-term experimental assessment of a new biodegradable vascular prosthesis for arterial replacement in the pig. Eleven pigs underwent bilateral carotid artery replacement with biodegradable electrospun poly-ε-caprolactone (PCL) nanofiber prostheses (internal diameter, 4 mm; length, 5 cm); or expanded polytetrafluoroethylene (ePTFE) prostheses as control. Perioperative anticoagulation was achieved with intravenous heparin (double baseline activated clotting time). Postoperatively, until conclusion of the study at 1 month, animals received aspirin and clopidogrel daily. Transit time flow was measured intraoperatively and at sacrifice. Doppler ultrasound (1 and 4 weeks) and a selective carotid angiography (4 weeks) were performed to assess patency. All explanted grafts were analyzed by histology, morphometry, and scanning electron microscopy in order to study graft-host interaction. RESULTS: Surgical handling and hemostasis of the new prostheses were excellent. Patency rate was 78% (7/9) for PCL grafts, compared with 67% (4/6) for ePTFE grafts. Transit time flow and Doppler ultrasound showed no significant changes in flow and velocity or diameter over time in both groups. Both prostheses showed no detectable in vivo compliance as compared with native carotid artery. Percent neoendothelialization was 86% for PCL and 58% for ePTFE grafts (P = .008). Neointima formation was equal in both grafts. More adventitial infiltration of macrophages, myofibroblasts, and capillaries was seen in PCL grafts with a milder foreign-body reaction when compared with ePTFE implants. Both grafts showed similar endoluminal thrombus formation. CONCLUSIONS: Biodegradable, electrospun PCL grafts showed good surgical and mechanical properties, no aneurysm formation, and similar short-term patency compared with ePTFE grafts. Rapid endothelialization and cell ingrowth confirms favorable PCL graft-recipient biological interaction. Despite good early results, long-term follow-up is required before clinical application.

Ascending aorto-superior mesenteric artery bypass as a surgical option for revascularization in mesenteric ischemia associated with type B aortic dissection.

We report the case of an acute ischemia of the superior mesenteric artery (SMA) after endovascular fenestration of a complicated acute type B aortic dissection. An initial attempt for endovascular revascularization of the SMA failed, and an ascending aorto-superior mesenteric artery bypass was urgently performed to salvage the small bowel. Surgery of patients in these specific settings is more complex because an adequate, more distal inflow vessel is often not present due to the dissected aorta and iliac arteries. This surgical option could be lifesaving and should be part of the vascular surgeon's armamentarium.

Isolated bilateral profunda femoris artery aneurysm.

BACKGROUND: Isolated bilateral profunda femoris artery aneurysm (PFAA) is a very rare entity. Most of the cases are unilateral and occur with synchronous aneurysms elsewhere. Symptoms range from none to limb ischemia or hemorrhage because of rupture. METHODS: We present a rare case of PFAA. In contrast to the general rule, the patient had a bilateral PFAA which was isolated to the deep femoral artery. The aneurysm was discovered after signs of acute limb ischemia caused by distal embolization. The patient was treated surgically with open aneurysmectomy and ligation of a branch of the deep femoral artery. CONCLUSION: PFAA are asymptomatic most of the time. Surgical repair is always recommended to prevent such life-threatening complications. Different treatment modalities are offered, including endovascular options. The presence of a PFAA should prompt screening for concomitant aneurysms.

Contrast enhanced ultrasonography versus MR angiography in aortocaval fistula: case report.

Aortocaval fistula (ACF) is a rare, life threatening complication of abdominal aortic aneurysms. Time to diagnosis is crucial as preoperative diagnosis and early surgical intervention significantly improve the outcome. The clinical spectrum being varied, the challenge of prompt and reliable diagnosis rests on emergency radiology. While the gold standard for detecting ACF today is CT angiography (CTA), frequently complicating renal insufficiency discourages the use of iodinated contrast making MR angiography (MRA) a useful alternative. Contrast enhanced ultrasound (CEUS) provides a promising new diagnostic option allowing rapid, non invasive and bedside diagnosis, especially in hemodynamically unstable patients. We present a case of prompt diagnosis of ACF by CEUS in comparison to modern MRA, thus establishing the new potential role of CEUS.

Pre-clinical validation of a new intra-operative "dual beam Doppler" blood flowmeter in an artificial circuit.

BACKGROUND: Intra-operative flow measurement during coronary or peripheral bypass operations is helpful for ruling out technical failures and for prediction of complication and patency rates. Preclinical validation of the flowmeters is required in order to rely on the intra-operatively measured results. The aim of this study is to evaluate a new "dual beam Doppler" blood flowmeter before clinical application and to compare it with the established "transit time flow measure-ment" technique in an artificial circuit. METHODS: Measurements were performed in an experimental flow model using pig blood and pig arteries. Three different flowmeters were used: Quantix OR (dual beam doppler flowmeter), CardioMed (transit time flowmeter), and Transonic (transit time flowmeter). Three validation tests were performed to assess correlation, precision, and repeatability of devices. (1) Correlation and agreement analysis was performed with various flow amounts (10-350 mL/min) (n = 160). (2) Device reproducibility and measurement stability were tested with a constant flow (flow amount = 300 mL/min) (n = 30). (3) A user accuracy test (intra- and inter-observer variability) was performed by 5 different observers with a constant flow (flow amount = 205 mL/min) (n = 75). Time collected true flow was used as a reference method in all steps and all tests were performed in a blind manner. Results are shown as mean values +/- standard deviations. Pear-son's correlation and Bland-Altman plot analyses were used to compare measurements. RESULTS: The mean flow was 167 +/- 98 mL/min for true flow and 162 +/- 94 mL/min, 165 +/- 94 mL/min, and 166 +/- 100 mL/min for Quantix OR, CardioMed, and Transonic, respectively. Correlation coefficients between Quantix OR, Medi-Stim, Transonic, and time collected true flow were over 0.98 (P = .01). Most of the measured results ( > 90%) were between +/- 1.96 SD agreement limits in Bland and Altman plot analysis. All devices showed good results in the reproducibility test. During the user accuracy test, larger variance changes were observed between intra- and inter-observer results with the dual beam Doppler flowmeter compared to the 2 used transit time flowmeters when used for single sided vessel access without stabilization device (available from the manufacturer). CONCLUSION: All 3 tested flowmeters showed an excellent correlation to the true flow in an artificial circuit and the accuracy of the tested devices was within agreement limits. Reproducibility of all devices was good and linear. The new dual beam Doppler flow measurement technique compares favorably to the classic transit time method. Clinical use may depend on operator, location, and condition, thus more studies may be required to ensure uniform results using the currently available blood flow measurement devices.

A novel high vacuum chest drainage system - a pilot study.

AIM: To assess the safety and feasibility of use of a novel high vacuum chest drainage system (HVCDS) and its influence on the cardiovascular system compared to a conventional system (CCDS). MATERIAL AND METHODS: Five anesthetized pigs underwent a median sternotomy. Three drains were placed in retrocardiac, retrosternal and left pleural positions. The animals received a HVCDS (22 Fr with 180 2-mm holes, n = 2) or a CCDS (n = 2). In the fifth animal off pump coronary artery bypass graft (OPCABG) stabilizers were tested. After chest closure animals had three 30 min runs of artificial bleeding (5 ml/min) under different negative aspiration pressures (-2, -20, -40 kPa) for both groups, followed by standardized surgical bleeding (-40 kPa - HVCDS, - 2 kPa - CCDS). Hemodynamic parameters and each drain's output were registered every 5 minutes and the residual blood was assessed. All catheters, the heart and left lung underwent macroscopic and histopathological examination. RESULTS: The application of the different pressures showed neither hemodynamic changes nor differences in blood drainage with both systems in two bleeding models. The HVCDS enabled drainage comparable to the CCDS but showed relevant clotting. Application of -20 kPa and -40 kPa caused macroscopic epicardial and pulmonary lesions in all tested devices including OPCABG stabilizers consisting of sub-epicardial or sub-pleural hemorrhage without myocyte or alveolar damage. CONCLUSIONS: The novel and conventional chest drainage systems used at pressures up to 40 kPa induced no hemodynamic instability. Both systems showed adequate equal drainage, despite major HVCDS clotting. High negative pressure drainage with both systems showed focal sub-epicardial and subpleural hemorrhage. Thus, long-term assessment of high pressure drainage and potential interaction with fragile structures (coronary bypass graft) should be carried out.

Hybrid treatment of an aortic arch aneurysm in a patient with a patent right and left internal mammary graft.

The aim of this report is to describe a known hybrid surgical and endovascular technique for aortic arch aneurysm repair in a special setting of a patient with previous coronary mammary bypass. We present a case of aortic arch aneurysm in a 66-year-old man with previous coronary bypass. He underwent a hybrid endovascular and surgical repair. All supraaortic vessels were debranched, keeping a continuous antegrade blood flow through the left and right internal mammary arteries to avoid myocardial ischemia. Endovascular treatment of aortic arch aneurysms is associated with less mortality and morbidity as compared with open surgery. The hybrid procedure with surgical debranching of the supraaortic vessels is the most commonly used method. In cases of previous coronary bypass with mammary arteries, care must be taken to maintain constant flow through the grafts during debranching.

Is the Surgical Safety Checklist successfully conducted? An observational study of social interactions in the operating rooms of a tertiary hospital.

OBJECTIVES: To determine whether the items on the Time Out and the Sign Out of the Surgical Safety Checklist are properly checked by operating room (OR) staff and to explore whether the number of checked items is influenced by the severity of the intervention and the use of the checklist as a memory tool during the Time Out and the Sign Out periods. METHODS: From March to July 2010, data were collected during elective surgery at the Geneva University Hospitals, Switzerland. The main outcome was to assess whether each item of the Time Out and the Sign Out checklists have been checked, that is, 'confirmed' by at least one member of the team and 'validated' by at least one other member of the team. The secondary outcome was the number of validated items during the Time Out and the Sign Out. RESULTS: Time Outs (N=80) and Sign Outs (N=81) were conducted quasi systematically (99%). Items were mostly confirmed during the Time Out (range 100-72%) but less often during the Sign Out (range 86-19%). Validation of the items was far from optimal: only 13% of Time Outs and 3% of Sign Outs were properly checked (all items validated). During the Time Out, the validation process was significantly improved among the highest risk interventions (29% validation vs 15% among interventions at lower risk). During the Sign Out, a similar effect was observed (19% and 8%, respectively). A small but significant benefit was observed when using a printed checklist as a memory tool during the Sign Out, the proportion of interventions with almost all validated items being higher compared with those without the memory tool (20% and 0%, respectively). CONCLUSIONS: Training on the proper completion of the checklist must be provided to OR teams. The severity of the interventions influenced the number of items properly checked.

Popliteal artery entrapment syndrome: report of two cases.

Popliteal artery entrapment syndrome accounts for an important part of correctible causes of claudication and limb ischemia in young people. It is caused by an abnormal relation between the popliteal artery (PA) and the medial head of the gastrocnemius muscle. The diagnosis should be considered in any patient under 50 with calf claudication. The mainstay of treatment is prevention of PA fibrosis because if left untreated, the syndrome leads to irreversible damage to the PA with thrombosis and limb ischemia. We describe two cases of different types in 21- and 27-year-old males, respectively, and we review the literature about the presentation, diagnosis, classification and management of this entity.

Mycoplasma hominis mediastinitis after acute aortic dissection repair.

We report a case of ascending aortic graft infection by an atypical bacteria, Mycoplasma hominis, with mediastinitis, a dreaded complication after cardiac surgery. A 55-year-old patient underwent ascending aorta replacement for acute type A dissection. He developed sternal instability and purulent discharge, requiring sternal wire removal and debridement. Cultures were initially sterile, but showed M. hominis infection after a significant delay and in specific culture media. The patient was treated with doxycycline and moxifloxacine. Cultures became negative and the sternum was closed on the 28th postoperative day after the first debridement. Recovery was favorable, with no signs of infection. Antibiotics were continued for one year. The patient is still asymptomatic 16 months after antibiotic interruption. Atypical organisms should be considered in the differential diagnosis of acute mediastinitis of unknown etiology after routine microbiological investigations.

Enhanced intimal thickening of expanded polytetrafluoroethylene grafts coated with fibrin or fibrin-releasing vascular endothelial growth factor in the pig carotid artery interposition model.

OBJECTIVE: Intimal hyperplasia and surface thrombogenicity are major factors in the high failure rate of synthetic small-diameter bypass grafts. Vascular endothelial growth factor is a potent stimulus for endothelial growth, and its provision in a fibrin matrix coating at the luminal graft surface may hold a key to spontaneous graft endothelialization and improved graft patency. METHODS: Pigs underwent bilateral carotid artery interposition of expanded polytetrafluoroethylene grafts either impregnated with fibrin (n = 11)--engineered to locally release vascular endothelial growth factor121 (vascular endothelial growth factor-fibrin; n = 11)--or left uncoated (n = 12). Graft patency was assessed by quantitative carotid angiography followed by graft histomorphometry at the 1-month experimental end point. RESULTS: Patency rates were not significantly different between study groups. Grafts coated with fibrin or vascular endothelial growth factor-fibrin exhibited significantly increased angiographic narrowing at the proximal anastomosis (for both P < .05 vs uncoated) and no difference at the distal anastomosis and the grafts' middle. Histological analysis showed 80% to 90% endothelial coverage and buildup of intima throughout the lengths of all grafts. Examination of the grafts' midportion revealed significantly enlarged neointimal layers of smooth muscle actin-positive cells in grafts coated with vascular endothelial growth factor-fibrin (242 +/- 47 microm2/micron) and fibrin (177 +/- 41 microm2/micron), compared with uncoated grafts (131 +/- 39 microm2/micron) (for both P < .05 vs uncoated). This thickening could not be explained by enhanced inflammation or vessel wall angiogenesis, which were minimal at the experimental end point. CONCLUSIONS: Fibrin and vascular endothelial growth factor produced effects deleterious to graft healing, by increasing the narrowing at proximal anastomosis and neointimal growth beyond that seen in uncoated grafts. It may reflect direct activation by exogenous vascular endothelial growth factor of vascular smooth muscle cells.

Effects of cryopreservation on the immunogenicity of porcine arterial allografts in early stages of transplant vasculopathy.

BACKGROUND: The number of revascularization procedures including coronary and lower extremity bypass, have increased greatly in the last decade. It suggests a growing need for vascular grafts. Cryopreserved allografts could represent a viable alternative but their immunologic reactivity remains controversial. METHODS: 71 pigs (40 recipients and 31 donors) were used. Two femoral grafts per recipient animal were implanted for 3, 7, and 30 days. Types of grafts: fresh autograft as a control graft (n=19), fresh allograft (n=31) and cryopreserved allograft (n=30). Histological and immunohistochemical studies were performed. RESULTS: Fresh allografts compared to autografts showed intimal inflammatory infiltration at 3 days (328 vs. 0 macrophages/mm2; P<0.05) and 7 days (962 vs. 139 T lymphocytes/mm2; P<0.05) post-transplantation. At 30 days, there was a loss of endothelial cells, presence of luminal thrombus and aneurismal lesions (total area=15.8 vs. 8.4 mm2; P<0.05). Cryopreservation did not reduce these lesions nor modify endothelial nitric oxide synthase (eNOS) expression nor modify the number of animals that developed anti-SLA antibodies. Moreover, at 7 days, cryopreserved allografts compared to fresh allografts showed a higher expression of P-selectin (5 out of 5 vs. 1 out of 5; P<0.05) and, at 30 days, a greater inflammatory reactivity (2692 vs. 1107 T lymphocytes/mm2 in media; P<0.05) with a trend towards a higher presence of multinucleated giant cells than in the fresh ones. CONCLUSIONS: The cryopreservation method used maintained immunogenicity of allografts and increased the inflammatory reactivity found in fresh allografts up to 30 days of vascular transplantation.