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Biomedical subjects

G Fishwick

Publications and source records attributed to G Fishwick.

At least 37 records · Page 2Linked to original sources
PubMed1999

Quality control during endovascular aneurysm repair: monitoring aneurysmal sac pressure and superficial femoral artery flow velocity.

PURPOSE: To use intraoperative aneurysmal sac pressure measurement and flow monitoring of the superficial femoral artery (SFA) to ensure complete exclusion of the aneurysm from the circulation. METHODS: A 5F catheter was positioned in the aneurysmal sac of 15 consecutive patients undergoing endovascular aortomonoiliac aneurysm repair between February and September 1997. The catheter was connected to an external pressure transducer allowing pressure monitoring throughout the operation and for 24 hours postprocedurally. Flow velocity was monitored in the contralateral SFA by insonation with a 2-MHz Doppler ultrasound probe. RESULTS: No technical defect was observed in the deployment of 10 endografts, which demonstrated marked reduction in sac pressure and good flow in the lower limb. The mean aneurysm pressure dropped from 123 to 57 mmHg after graft insertion. In 5 cases, monitoring detected problems during the endograft procedure. In 3, incomplete stent deployment was detected by a failure of sac pressure to fall following stent inflation and by the presence of flow in the contralateral femoral artery. In the other 2 cases, a distal endoleak was detected by direct injection of contrast into the sac. CONCLUSIONS: Measuring aneurysm pressure in combination with SFA Doppler flow monitoring can detect complications of endovascular aneurysm repair.

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PubMed1998

Is endoluminal abdominal aortic aneurysm repair using an aortoaortic (tube) device a durable procedure?

Endoluminal repair of abdominal aortic aneurysm (AAA) is being adopted as a less invasive alternative to conventional open repair in many centers worldwide. Although the initial results are encouraging, the long-term durability of this procedure remains unknown. Endoluminal AAA repair in 29 patients using three different devices (EVT tube Endograft(R), aortouniiliac device, and Stentortrade mark bifurcated system) is described. Overall, 24 procedures (83%) were completed successfully. Complications included two deaths due to microembolization, five early conversions, two chest infections, three patients with buttock claudication, and three patients with trashed foot. Perigraft leaks were detected in four patients (three proximal, one distal) treated with the EVT tube Endograft. Continued aneurysm expansion was observed in three of the patients. One of the leaks was discovered at the 1-year follow-up. In this patient the aneurysmal process was not retarded by endoluminal repair. The findings in this patient may have implications for the durability of this technique. Therefore, careful long-term evaluation of this procedure is recommended prior to its widespread use.

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PubMed1998

A comparison between colour duplex ultrasonography and arteriography for imaging infrapopliteal arterial lesions.

OBJECTIVE: To investigate the agreement between colour duplex ultrasonography and digital subtraction arteriography of the infrapopliteal arteries. DESIGN: Retrospective, blinded study. SETTING: Vascular laboratory and Radiology Department, University Hospital. METHODS: The infrapopliteal vasculature was examined in a total of 51 limbs by both colour duplex ultrasound and digital subtraction angiography. By examining all arteries from the distal popliteal to the pedal arteries, a total of 204 individual arterial segments were available for analysis. Each segment was graded as 0-49%, 50-99% diameter reduced or occluded by both modalities. Using ultrasound, classification of stenoses was achieved by observing peak systolic velocity ratios; a doubling of peak systolic velocity indicating a > or = 50% diameter reducing stenosis. Where no Doppler signal could be obtained, the vessel was assumed to be occluded. From angiographic studies, two radiologists separately and blindly assessed the extent of disease for each infrapopliteal artery noting areas of > or = 50% diameter reduction and occlusion. The Kappa statistic was used to examine the level of agreement between angiography and ultrasound as well as between both radiologists. RESULTS: The Kappa level (95% confidence interval) of agreement between ultrasound and angiographic assessments for distinguishing patent from occluded segments was 0.61 (0.49-0.74) for all segments. The equivalent agreement between radiologists was 0.80 (0.70-0.89). Poorest agreement was observed from ultrasound assessments of the peroneal and tibioperoneal trunk arterial segments. CONCLUSION: Since agreement between colour duplex scanning and angiography never fell significantly below levels achieved between two radiologists, we conclude that colour duplex ultrasound can be used to assess infrapopliteal artery patency.

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PubMed1998

The influence of dietary supplementation with urea on resilience and resistance to infection with Haemonchus contortus.

Previous research has indicated that supplementing an apparently adequate diet with additional protein improves both host resistance and resilience in lambs infected with Haemonchus contortus. The present study tested the influence of supplementation with non-protein nitrogen (urea). Helminth-naive Hampshire Down lambs were given an apparently adequate basal diet or a diet supplemented with urea. The lambs were then infected with Haemonchus contortus for 10 weeks. Supplementation with urea had no discernible effect on resistance to infection; faecal egg counts, worm burdens, worm lengths and mean number of eggs per adult female worm did not differ between the 2 groups. However, lambs on the supplemented diet showed better resilience; they had greater packed red cell volumes, higher plasma albumin concentrations and increased liveweight gain compared to lambs on the basal diet. The loss of appetite following infection was less in lambs fed the urea-supplemented diet. The observed effect of urea supplementation was seemingly due to greater food consumption as well as the better diet.

Animal Nutritional Physiological Phenomena↗
PubMed1998

Comparison of computed tomography and duplex imaging in assessing aortic morphology following endovascular aneurysm repair.

BACKGROUND: Computed tomography (CT) has been used to assess patients following endovascular aneurysm repair to determine the need for secondary endoluminal or operative procedures. This prospective study compared CT and duplex imaging to evaluate aneurysm morphology following endoluminal aortic grafting. METHODS: Twenty patients were evaluated at regular intervals following successful endoluminal aneurysm repair. CT and duplex scanning were compared in their ability to determine aneurysm and aortic diameter, the presence of perigraft extravasation (endoleaks) and technical defects in the endograft. RESULTS: In 20 patients who were assessed 6 months after operation, duplex imaging identified four endoleaks (two early, two late; one proximal, three distal). In three cases, the aneurysm diameter progressively increased after operation. In patients with a thrombosed aneurysm sac, the aneurysm regressed at a median of 0.40 (range 0.13-0.8) cm per year. The CT findings were similar (median regression 0.43 (range 0-1.0) cm per year), although CT was unable to predict the site of the leak as accurately as duplex imaging. CT demonstrated that the diameter of the juxtarenal aorta increased following endografting. CONCLUSION: Duplex imaging is a less invasive, less costly alternative to CT in the follow-up of patients after endoluminal aortic surgery. Increase in size of the aneurysm sac following endovascular aneurysm repair strongly suggests the presence of an endoleak.

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PubMed1998

Torsion and kinking of unsupported aortic endografts: treatment by endovascular intervention.

PURPOSE: To describe the management strategies used to deal with twisted aortic endografts. METHODS AND RESULTS: Two patients with successfully excluded aortic aneurysms developed symptoms referable to previously undetected twists in their endografts (one EndoVascular Technologies [EVT] and one customized aortomonoiliac device). The limb graft occlusion in the EVT graft was treated surgically with a femorofemoral bypass, but the aortomonoiliac endograft was salvaged with percutaneous implantation of a Wallstent. During another aortomonoiliac procedure, suboptimal flow through the endograft was traced to contortion of the endograft as it passed over an angulated proximal aneurysm neck. An X-large Palmaz stent was deployed to support the graft at this point. CONCLUSIONS: Unsupported aortic endografts may develop twists and kinks during deployment that can lead to low outflow and graft occlusion. Endovascular techniques are available to repair these defects postoperatively, although more precise intraoperative assessment tools may identify these problems so that they can be corrected at the initial intervention.

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PubMed1998

Endovascular repair of aortic aneurysms in the the presence of a horseshoe kidney.

PURPOSE: To report two cases of endovascular aortic aneurysm exclusion in patients with a horseshoe kidney. METHODS AND RESULTS: Two male patients, one with a known horseshoe kidney and history of multiple previous laparotomies, presented with abdominal aortic aneurysms of approximately 6-cm diameter. Each was treated with a tapered aortomonoiliac polytetrafluoroethylene graft secured proximally with a Palmaz balloon-expandable stent. The endograft was sutured distally to a Dacron femorofemoral crossover graft. An anomalous renal vessel was sacrificed in one case. The aneurysms were successfully excluded, and the patients recovered without sequelae. CONCLUSIONS: Endovascular repair should be considered as a treatment option in patients with aortic aneurysm in the presence of a horseshoe kidney, particularly if the renal vasculature can be wholly preserved.

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PubMed1997

Aortomonoiliac endovascular grafting: difficult solutions to difficult aneurysms.

PURPOSE: To describe a refined technique for aortomonoiliac endograft exclusion of abdominal aortic aneurysms (AAAs). METHODS: A tapered aortomonoiliac graft was prepared from an 8-mm thin-walled expanded polytetrafluoroethylene tube graft predilated proximally to 35 mm and tapered distally to 15 mm. The proximal graft was sutured to a 5-cm-long, predilated Palmaz stent, which was mounted on a 30-mm balloon and backloaded into a 21F packaging sheath. With the patient under general anesthesia and both common femoral arteries exposed, the endograft was anchored in the infrarenal aorta and subsequently passed into one iliac system, where it was anastomosed to the iliac or femoral vessels. The contralateral common iliac artery was occluded, and an extra-anatomic, femorofemoral, or iliofemoral bypass grafting was performed. RESULTS: Twenty of the 25 AAAs treated to date with this technique have been successful, with aneurysm exclusion achieved in 18 (2 minor distal endoleaks are scheduled for endovascular repair). The technical failures were analyzed, resulting in enhancements to the technique. Complications included 2 early (< 30 days) deaths, 1 case of minor embolization, 1 transient renal failure, 1 pulmonary embolus, and 1 wound infection. The only late complication was a graft infection localized to the groin. CONCLUSIONS: Aortomonoiliac endovascular aneurysm repair is effective in patients with AAAs involving the iliac arteries. Short-term results are acceptable, but long-term efficacy must be addressed before this procedure is widely adopted. Technical changes made in response to early learning curve problems have led to a safer, more reliable procedure.

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PubMed1996

Influence of soyabean meal supplementation on the resistance of Scottish blackface lambs to haemonchosis.

Protein supplementation improves the resistance of sheep to haemonchosis. This experiment investigated the Scottish blackface breed to establish whether dietary protein supplementation is still beneficial in a genetically resistant breed. Lambs were given either a basal diet or a diet supplemented with soyabean meal to give an additional 80 g crude protein kg dry matter-1. The lambs were given an initial loading dose of Haemonchus contortus, followed by a trickle infection for 10 weeks. The weight gains of the lambs given the supplemented diet were greater and their carcases were leaner, irrespective of infection status. Infected animals on the basal diet were more anaemic and hypoalbuminaemic than animals receiving the supplemented diet, although there were no statistically significant differences in mean worm burdens or faecal egg counts.

Analysis of Variance↗
PubMed1996

Proximal stent deployment without contrast during endovascular aneurysm repair: an improved technique.

PURPOSE: To describe a technique to enhance stent visibility on the fluoroscopic monitor during aortic endograft deployment. TECHNIQUE: To assist in accurate positioning and deployment of the proximal stent in a Parodi-type aortic endograft, the stent is affixed to the balloon so that the radiopaque marker sits at the stent's distal end. When the device is in position and the sheath is retracted, the stent and the radiopaque balloon markers are clearly seen on the fluoroscopic image. Using normal saline only to inflate the balloon allows the stent to remain visible throughout deployment. CONCLUSIONS: The use of saline rather than contrast medium for balloon inflation provides continuous visualization of the stent during expansion, thus facilitating accurate deployment and early recognition of balloon migration within the stent.

Angioplasty, Balloon↗
PubMed1995

Influence of supplementation with dietary soyabean meal on resistance to haemonchosis in Hampshire down lambs.

The influence of dietary protein supplementation on resistance to haemonchosis was examined in Hampshire down lambs fed either a basal diet or a diet supplemented with soyabean. At seven months of age the lambs were challenged with an initial loading dose of Haemonchus contortus, followed by a trickle infection three times a week. Blood and faecal samples were collected three times a week and bodyweights were recorded weekly. After 10 weeks the lambs were slaughtered and their worm burdens and carcase composition determined. Although their mean worm burdens were similar, the lambs given the basal diet had higher faecal egg counts, lower packed red cell volumes and lower concentrations of total plasma protein and plasma albumin than the lambs given the supplemented diet. The dietary supplementation also improved the carcase composition of the lambs.

Animal Feed↗
PubMed1995

The influence of energy intake on the pathophysiology of Trypanosoma congolense infection in Scottish blackface sheep.

The intensity of parasitaemia, degree of anaemia, live body weight gains and blood biochemical changes were measured in two groups of Scottish Blackface sheep infected experimentally with Trypanosoma congolense and allowed either a high (9.9 MJ metabolisable energy (ME) day-1) or a low (6.1 MJ ME day-1) energy intake. It was observed that infected animals on the low energy intake had a longer mean prepatent period, but following patency they developed more severe anaemia and greater growth retardation than those on the high energy intake. Both infected groups exhibited significant reductions in serum total lipids, phospholipids, plasma cholesterol and albumin. However, these changes were more severe in the animals on the low energy intake than in those on the high energy intake. It was concluded that adequate energy nutrition enhances the ability of infected animals to withstand the adverse effects of infection, by promoting body weight gains and moderating the severity of the pathophysiological changes associated with ovine trypanosomosis.

Anemia↗
PubMed1993

The pathophysiology of Trypanosoma congolense infection in Scottish blackface sheep. Influence of dietary protein.

The intensity of parasitaemia, degree of anaemia, blood biochemical changes and live weight gains were measured in two groups of Scottish Blackface sheep infected experimentally with bloodstream forms of Trypanosoma congolense and given either a high or a low protein diet. It was observed that infected animals on a high protein diet tended to develop a higher intensity of parasitaemia than those on a low protein diet. Both groups of infected sheep exhibited similar degrees of anaemia, but the erythropoietic activity, as judged by the increase in mean corpuscular volume and appearance of normoblasts in the circulation, was significantly greater in animals on a high protein diet. The infected animals on a high protein diet gained weight at a similar rate to their uninfected controls, while those on a low protein diet gained significantly less than their controls between 0 and 70 days after infection. Following treatment with the trypanocidal drug isometamidium chloride, both infected groups recovered from the anaemia. However, the rate of recovery was faster in animals on a high protein diet than in those on a low protein diet. It was concluded that high protein intake ameliorates the adverse effects arising from infection, as assessed by the severity of anaemia and weight changes, and also enhances the rate of recovery following chemotherapy.

Anemia↗