Biomedical subjects
G Stansby
Publications and source records attributed to G Stansby.
Angioplasty of lower limb arterial stenoses under ultrasound guidance: single-center experience.
PURPOSE: To examine the feasibility and utility of ultrasound-guided angioplasty for treating lower limb stenoses. METHODS: Duplex ultrasonography was employed to guide 55 balloon dilation procedures (27 iliac, 26 superficial femoral, 1 profunda, and 1 vein graft) with the help of a special ultrasound catheter (EchoMark). Ultrasound was used to determine balloon size, monitor guidewire passage, direct the dilation, and judge procedural success. Angiography was performed prior to the procedure to confirm preprocedural ultrasound findings and afterward to compare with duplex visual and hemodynamic parameters of success (peak systolic velocity ratio < 2.0). RESULTS: The balloon size determined from duplex measurements correlated in all cases with sizes selected based on the angiographic image. Guidewire visualization was possible in 95% of the cases. Angioplasty using ultrasound alone was feasible in 84%; inability to obtain a satisfactory image owing to vessel tortuosity, calcification, and bowel gas accounted for the failures. Against the duplex success criterion, initial completion angiograms had an accuracy of 76%, sensitivity of 76%, and specificity of 100%. The additional time for ultrasound guidance averaged 42 +/- 12 minutes for all cases. CONCLUSIONS: Our results show that ultrasound guidance is feasible in routine clinical practice. In this series of well-selected cases of arterial stenoses, angioplasty was performed safely using ultrasound guidance alone in over 80% of the cases. Fluoroscopic monitoring is needed when ultrasound visualization is suboptimal.
Plasma endothelin-1 concentrations in non-insulin-dependent diabetes mellitus and nondiabetic patients with chronic arterial obstructive disease of the lower limbs.
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Vein quality in vascular surgery.
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Deuterium oxide-based University of Wisconsin solution improves viability of hypothermically stored vascular tissue.
BACKGROUND: Preservation of vascular function largely determines the outcome of transplantation. We have investigated replacing the water (H2O) in University of Wisconsin (UW) solution with deuterium oxide (D2O) in an attempt to improve vascular function after hypothermic storage. METHODS: Rat aortic segments were stored in UW solutions based on 100% H2O, 25% D2O, 50% D2O, and 100% D2O at 4 degrees C for 24, 48, or 72 hr. Vascular function was measured via contraction and endothelium-dependent relaxation after stimulation with phenylephrine and acetylcholine. RESULTS: UW solution with 25% D2O gave a significant (P<0.05) improvement of contraction and relaxation in comparison with H2O-based UW solution and other concentrations of D2O. CONCLUSIONS: Low concentrations (25%) of D2O-UW solution are significantly superior to the H2O-based (i.e., commonly used) equivalent at up to 72 hr. These results suggest that low concentrations of D2O-UW solution can improve the quality of hypothermic storage.
Effect of cryopreservation on Gal alpha 1-3Gal expression on adult porcine pancreatic islets.
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Spinal cord complications of thoracoabdominal aneurysm surgery.
BACKGROUND: Although rare, paralysis secondary to spinal cord ischaemia after aortic aneurysm surgery is a devastating complication. Many papers have been published on this topic but without a clear consensus on the best way of minimizing the problem. Recent articles have included advanced pharmacological approaches and the literature has been reviewed in light of these. METHODS: Relevant papers were identified by an extensive text word search of the Medline database and a review of quoted articles. RESULTS: Spinal cord complications are commoner after the repair of Crawford type II aneurysms than less extensive aneurysms. The presence of dissection, rupture and prolonged clamp times are associated with an increased incidence. About a quarter of all cord problems develop over 24 h after surgery and this may be due to a reperfusion type injury, although the exact mechanisms are by no means clear. CONCLUSION: A combination of rapid surgery, left heart bypass for the repair of more extensive aneurysms, free spinal drainage and the avoidance of postoperative hypoxia and hypotension help to minimize spinal cord ischaemia. No pharmacological agent has yet been shown conclusively to improve outcome in the clinical setting.
Role of magnetic resonance angiography for assessment of abdominal aortic aneurysm before endoluminal repair.
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Early effect of carotid endarterectomy on arterial blood pressure measured with an ambulatory monitor.
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Thromboembolism prophylaxis during laparoscopic cholecystectomy.
BACKGROUND: The aim of this study was to determine current UK practice with regard to thromboembolism prophylaxis during laparoscopic cholecystectomy. METHODS: Postal questionnaires were sent to 800 members of the Association of Surgeons; replies were received from 551 surgeons (69 per cent) of whom 417 practised laparoscopic cholecystectomy. RESULTS: Heparin was prescribed to all patients by 74 per cent, and selectively by 20 per cent, of respondents. Surgeons who performed fewer than ten laparoscopic cholecystectomies per annum were significantly less likely to use heparin (P < 0.001) and more likely to believe that heparin produces significant adverse bleeding (P < 0.01). Thirty per cent of respondents used low molecular weight heparin. Stocking to deter thromboembolism were used by 74 per cent, and pneumatic compression by 37 per cent. Indications for heparin varied considerably and were not influenced by Thromboembolic Risk Factors (THRIFT) guidelines. Only 20 per cent of respondents considered that thromboembolism was a problem; 91 per cent reported that they had never experienced a thromboembolic complication following laparoscopic cholecystectomy. CONCLUSION: The rate of thromboembolism after laparoscopic cholecystectomy is unknown but most surgeons believe the risk is very low. Surgeons' attitudes towards thromboembolism prophylaxis are variable, but most experienced surgeons use low-dose heparin.
Clostridium difficile colitis after aortic surgery.
OBJECTIVE: To determine the incidence and outcome of Clostridium difficile colitis (CDC) following aortic surgery. DESIGN: Retrospective clinical study, and case-note review. PATIENTS: Of 180 patients undergoing aortic surgery for either aneurysmal or occlusive disease between 1 September 1994 and 31 August 1996 (24 months), 15 (8.4%) developed CDC. There were 12 male and three female patients of median age 65 (range 46-84). RESULTS: Two patients died from multiple organ failure in association with CDC, one of whom underwent negative relaparotomy for suspected ischaemic bowel because the diagnosis of CDC had not been entertained. Previously identified risk factors for CDC comprised: age > 65 (eight); renal impairment (four); chronic obstructive airways disease (seven); coexistent malignancy (three); admission from another hospital (four); H2 antagonist therapy (13); ITU (nine); and/or HDU care (14). Diarrhoea commenced a median of 9 (range 5-26) days, and CDC, was diagnosed a median of 14 (range 10-26) days after operation. All patients received intravenous Cefuroxime, originally prescribed as prophylaxis, for a median of 6 (range 3-16) days prior to onset of CDC. Two patients received 1 additional antibiotic; one received 2; two received 3; and one received 4 prior to onset of CDC. CONCLUSIONS: CDC is a common and potentially serious complication of vascular, and in particular, aortic surgery. Although such patients often possess several risk factors for CDC, colitis frequently follows prolonged 'prophylactic' cephalosporin administration, which should therefore be avoided.
Retroperitoneal endoscopic iliofemoral cross-over graft for critical limb ischaemia.
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Superficial femoral vein graft donation from the amputated limb.
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Short-term exposure to low concentrations of thapsigargin inhibits replication of cultured human vascular smooth muscle cells.
BACKGROUND: Central to the pathophysiology of stenosis following balloon angioplasty and arterial bypass surgery is proliferation of vascular smooth muscle cells (VSMCs). To investigate the role of calcium (Ca2+) in VSMC proliferation, the effect of thapsigargin, Ca2+ ionophore A23187, ionomycin, cyclopiazonic acid and di-tert-butylhydroquinone (all of which raise intracellular Ca2+ levels) on the proliferation of cultured human VSMCs was observed. METHODS: Cultured VSMCs from human saphenous vein were treated with calcium-modulating drugs and proliferation was assessed by determining [3H]thymidine and 5-bromo-2'-deoxyuridine incorporation and cell number. RESULTS: Over a 48-h exposure, thapsigargin inhibited VSMC replication (median 50 per cent maximal inhibitory concentration 2 nmol/l) whereas the other drugs were much less effective. Short-term exposure (5, 10, 30 and 60 min) to thapsigargin elicited a significant dose-dependent inhibition of VSMC replication whereas, again, the other drugs were without significant effect. CONCLUSION: Thapsigargin-sensitive intracellular Ca2+ pools play a key role in controlling VSMC proliferation and specialized means of administering thapsigargin may constitute a possible approach to preventing stenosis.
Endoscopic subfascial division of incompetent perforating calf veins.
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Recurrent panniculitis as the first clinical manifestation of recurrent acute pancreatitis secondary to cholelithiasis.
A case of recurrent panniculitis in the legs as the first clinical manifestation of recurrent acute pancreatitis secondary to cholelithiasis is described in a 59-year-old Caucasian woman.
Homocysteine and vascular disease.
There is increasing evidence that a raised blood level of homocysteine (HC) is a risk factor for premature atherosclerosis. With a gene frequency between one in 70 and one in 200 this condition may be more common than previously thought. It should be suspected especially in young patients in whom other risk factors are absent. The diagnosis may be made by demonstrating raised plasma HC levels, either basally or after methionine loading. Studies have shown significantly increased levels of HC in patients with premature coronary artery, peripheral vascular and cerebrovascular disease. The mechanisms by which HC produces vascular damage are, as yet, not completely understood but endothelial injury is probably a central factor. The principle of treatment is to lower HC levels in the blood by administration of vitamin B6, vitamin B12, folate or betaine. How effective this strategy will be in preventing complications is not yet known.