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Our report encompasses two cases of Dacron patch infection following carotid endarterectomy and a systematic review of the literature. Particular attention is placed on the incidence, aetiology, investigation, presentation and management dilemmas of this rare complication of carotid surgery. We present all known cases of synthetic patch infection following carotid endarterectomy over the last 12 years. 14 publications have been identified totalling 77 cases of graft infection. Approximately 0.25-0.5% of all Dacron patches appear to get infected. Infection may present early or late and appears to have a bi-modal distribution depending on the presence of low- or high-grade infection. Post-operative complications especially wound haematoma is associated with the later development of infection. Most patients present with pseudoaneurysm formation, neck swelling or a draining local sinus and are infected with either Staphylococcus epidermidis or Staphylococcus aureus. Duplex ultrasound is the investigation of choice and complete excision of all infected material and arterial reconstruction with a vein patch or graft is recommended. Dacron patch infection is a rare but recognised complication of carotid surgery and knowledge of this condition is vital for vascular surgeons and other speciality surgeons to whom cases may present.

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Forty carotid endarterectomies were undertaken in 34 patients. Operations were prospectively randomized to periarterial application of either 1 per cent lignocaine (n = 19) or normal saline (n = 21), and detailed measurements taken of intraoperative pulse rate and blood pressure. Patients receiving lignocaine demonstrated a lower pulse rate, and lower systolic and mean blood pressures than those receiving placebo, with significance in relation to clamp application and shunt removal (P < 0.05). It was particularly noticeable that patients receiving lignocaine demonstrated less intraoperative variation in pulse rate and blood pressure. Topical lignocaine stabilizes pulse rate and blood pressure during carotid endarterectomy.

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Mallory Weiss tears are a common cause of upper gastrointestinal bleeding, typically reported as following repeated vomiting after an alcoholic binge. This association may have been overemphasised, and these lesions could be caused by a wide range of spontaneous and iatrogenic events. A case of sudden postoperative death caused by massive haematemesis, unheralded by any evidence of vomiting or retching, as a result of Mallory Weiss tears is reported.

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Three cases of true aneurysms of the profunda femoris artery are reported along with a review of 17 other cases in the literature. These aneurysms are rare and commonly present with rapid enlargement or rupture (9/20), the risk of rupture being higher than those affecting the femoral or popliteal arteries. All patients underwent successful surgical treatment except for one who required amputation. The diagnosis of an aneurysm of the profunda femoris artery must be considered in all patients with a pulsatile swelling in the groin. Surgical treatment is mandatory, and it carries a low mortality as well as a low risk of amputation.

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An inexpensive image processing system, assembled from commercially available components and driven by "in-house" software, was tested as a means of processing radiographs obtained in a radiology department. In this preliminary study, the main interest was to investigate, through subjective appraisal, the ability of the system to recover the image quality of poorly exposed radiographs. Subsidiary objectives were to obtain some information regarding the specification limits of the system and its components, as well as some quantitative estimate of its advantages for clinical diagnosis. The system was used to process a set of film radiographs of an anthropomorphic chest phantom, produced under conditions that were designed to provide a wide range of image qualities. Following this, four sets of randomly ordered processed and unprocessed images were formally assessed by a group of experienced observers. Consensus opinion from the group indicated that significant improvement could be obtained through simple image processing. Some radiographs regarded as unacceptable became, after processing, acceptable to viewers.

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Osteryoung square-wave voltammetric analysis is a rapid technique that can be used to determine nicarbazin residues in chicken tissue. The method is reproducible and can be applied to samples containing as little as 1-10 mug/g nicarbazin. This level of sensitivity is more than adequate for meeting governmental regulations. Osteryoung square-wave voltammetry is significantly faster than classical differential pulse polarography.

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No synthetic prosthesis has yet been found which can satisfactorily be used as a substitute for saphenous veins in vascular surgery. One explanation for the lack of success is that their properties and behaviour do not mimic those of the arteries they replace. The essential features for a successful vascular prosthesis, over and above biocompatibility, are a low friction non-thrombogenic flow surface, mechanical (elastic) behaviour that matches natural artery and dimensions that approximate the host vessels. This will allow a high velocity of flow with low impedance. A prosthesis with this specification would avoid the problems of flow disturbances and reflection at the anastomoses, pulse wave damping and large pressure gradients, all of which reduce pulsatile energy. We have designed a vascular prosthesis based upon the above criteria. It has an internal diameter of 4 mm and a wall thickness of 1 mm. Its geometry makes it kink resistant and a good match for tibial and coronary arteries. The prosthesis is made from polyurethane and its mechanical properties, which approximate to those of peripheral arteries, are achieved via a mechanism of internal wall compression rather than external circumferential expansion. To assess the in-vivo potential of this prosthesis, 21 grafts were implanted in 11 sheep, replacing a section of carotid artery with a 6 cm long prosthesis. All 21 grafts were patent after 3 months. One graft was removed for histological examination. 16 of the remaining 20 grafts were patent after 7 months. Problems associated with thrombosis were not encountered and we conclude that this prosthesis shows good potential as a small bore vascular substitute.

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Analysis of the morphological aspects of continuous-wave Doppler examination is a reliable means of detecting carotid stenosis involving 50% or more of the diameter of the arterial lumen. This study was undertaken to evaluate the indexes likely to increase the diagnostic accuracy of this noninvasive investigation method. The indexes studied were the variations of the maximal frequency and the systolic peak frequencies, measured proximal to and at the level of stenosis, and the ratio of the systolic peak frequency measured in the internal carotid artery and in the common carotid artery. After obtaining data on an experimental model, the study was conducted in healthy volunteers (n = 24) and in patients with carotid atherosclerotic disease (n = 23). The experimental study confirmed that stenosis greater than 50% leads to a reduction of blood flow and that there is a mathematical relationship between the frequency measured proximal to and at the level of the stenosis and the degree of stenosis. Clinical data showed that there was a significant decrease in the frequency of the systolic peak in elderly "healthy" subjects as compared with younger subjects. However there was no difference between patients with and without stenosis. The index was 0.8 in young subjects, 1.3 in healthy elderly subjects, and greater than 1.3 in subjects who had a stenosis. There was no statistically significant difference between these two last groups. At the threshold value of 2.3, the sensitivity of the FI index was 22% and the specificity was 94% in the detection of carotid artery stenosis. In the assessment of the tight stenosis, sensitivity was 44%.

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In this prospective study, the reliability of the morphologic analysis of the continuous Doppler signal was evaluated. Three parameters were considered: the maximum systolic frequency (max A), a resistance parameter (RP) and the degree of spectral broadening (SB). The apparatus used allowed us to construct a color arterial image. Seventy-four subjects were included in this study: 17 volunteers investigated by ultrasound only, and 57 patients investigated by ultrasound and arteriography. Anatomic correlation was obtained in 31 operated cases. The threshold values, as determined in the volunteers, were as follows: 3.5 kHz for max A, 0.86 for RP and 58% for SB. Sensitivity was 94% when max A, SB and cartography were combined to detect tight stenoses. The sensitivity for each of the parameters alone was much weaker (61% for max A and 33% for RP). For all carotid lesions, the sensitivity of detection when all parameters were combined was 68%. Specificity was 77%. The study of the carotid bifurcation by the continuous Doppler effect allowed us to identify tight stenosis with reliability. On the other hand, it was impossible to distinguish between normal arteries and moderate stenosis, or between tight stenosis and complete occlusion.

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In a prospective study the incidence, causes and management of atypical claudication have been investigated. All patients had a clinical assessment, Doppler ultrasound studies and X-rays of the lumbosacral spine, some had epidural injections, myelography with computerized axial tomography and arteriography. The incidence of atypical claudication was low, 13 per cent of all claudicants referred to our department, and although difficulties in diagnosis were encountered an approximately equal incidence of spinal and arterial causes was found. Only one patient had a definite central spinal stenosis. The need for invasive investigations was low (18 per cent) and even lower for surgery (7 per cent); the majority of patients' symptoms responded to conservative management.

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The physical quality of a digitised image is affected by non-digital processes in the imaging instrumentation and by digital processes in the computer. The spatial unsharpness depends on instrumental resolution and on the pixel size of the digital array. The image contrast depends on the properties of the imaging system and on the number of grey scales used in the digital sampling process. The possibility is examined of constructing formulae for spatial unsharpness, and for the analogous parameter in the intensity dimension, defined as threshold contrast, in terms of instrumental and digital components. Formulae are developed from simple principles and tested against the observed properties of computer simulated images. The conclusion is that the concepts and the formulae provide a basis for predicting the effects of digital processing on the total unsharpness and contrast of digitised images.

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