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Biomedical subjects

S T MacSweeney

Publications and source records attributed to S T MacSweeney.

At least 19 recordsLinked to original sources
PubMed2005

Cerebral white matter hyperintense lesions are associated with unstable carotid plaques.

OBJECTIVES: The aim of this study was to determine whether unstable carotid plaques, a known risk factor for cerebral emboli, are associated with cerebral white matter lesions. METHODS: Seventy-one symptomatic patients undergoing magnetic resonance imaging prior to carotid endarterectomy for high grade carotid stenosis were included in this study. The number and volume of white matter hyperintense lesions (WMHL) on fluid attenuated inversion recovery brain scans were compared according to the morphology of carotid plaque based upon the American Heart Association (AHA) histological classification. RESULTS: Of the 57 patients who had good quality brain scans and non-fragmented carotid plaques, 15 plaques were defined as stable (type V) and 42 as unstable (type VI). After adjustment for the major risk factors affecting WMHL, unstable carotid plaques were found to be associated with more WMHL in the ipsilateral cerebral hemisphere than stable plaques (transformed means 2.50+/-1.2 vs. 1.53+/-1.1, p=0.016), however, there was only a trend towards larger WMHL volumes (p=0.079). CONCLUSIONS: The observed association between unstable carotid plaques and the number of white matter lesions suggest that thromboembolic plaque activity may contribute to the development of leukoaraiosis, in particular smaller individual lesions. Larger studies are warranted to confirm this finding and explore the potential clinical impact for selecting candidates for carotid endarterectomy.

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PubMed2001

Endovascular repair of ruptured abdominal aortic aneurysm--a challenge to open repair? Results of a single centre experience in 20 patients.

INTRODUCTION: The mortality from ruptured abdominal aortic aneurysm (AAA) remains in the region of 50% despite advances in critical care. Endovascular repair of AAA has been shown to be associated with reduced physiological stress in the elective setting. It is hypothesised that the reduced physiological stress associated with EVAR may improve the outcome in patients with ruptured AAA. METHODS: A feasibility study of endovascular repair of ruptured AAA was undertaken at the University Hospital, Nottingham, U.K. between 1994 and 2000. Patients admitted with ruptured AAA were assessed by a team familiar with endovascular techniques for elective repair of AAA. After giving informed consent patients underwent spiral computed tomographic angiography (CTA) in the majority of cases. Patients were then transferred to the operating theatre for EVAR. RESULTS: Twenty patients underwent repair of ruptured AAA. Of these 20 patients, seven were referred from another hospital. Eight patients were considered unfit for open repair. The median duration of procedure was 180 min (range 120-480) and median blood loss was 1200 ml (range 750-2000 ml). The overall peri-operative mortality was 45%. A number of intra-operative and peri-operative procedures (both open and endovascular) were required to ensure aneurysm exclusion and to deal with the complications of endovascular surgery. CONCLUSIONS: Ruptured AAA remains a particularly hazardous condition to treat. There are a number of advantages of EVAR in this condition. A number of the problems early in the experience of EVAR have been addressed, but further experience is required to demonstrate its efficacy when compared with open repair.

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PubMed2000

Variation of method for measurement of brachial artery pressure significantly affects ankle-brachial pressure index values.

BACKGROUND: Mmeasurement of ankle brachial pressure indices (ABPI) is important in the assessment of patients with peripheral vascular disease. METHODS: Thirty-one hospitals with a vascular surgeon were selected at random. A telephone questionnaire was completed to assess the method used for the measurement of ABPI. Following the survey, 14 patients with peripheral vascular disease had their ABPI measurement done by two observers, a pre-registration house officer and a clinical nurse practitioner. Observers were blinded to their own and each other's results. Brachial systolic pressures were obtained using a DINAMAP(TM)(Critikon, Tampa, U.S.A.) automated blood pressure monitor, the Korotkoff method (12 cm cuff, parallel wrap) and an 8 MHz Doppler probe (Huntleigh) and sphygmomanometer. Ankle systolic pressures were obtained using the Doppler probe. The results were analysed using the Wilcoxon signed rank test. RESULTS: The survey demonstrated that at the majority of centres with vascular laboratories the brachial artery systolic pressures were measured using a Doppler probe. In contrast, at centres where the house officers performed the routine measurements, over 60% used the Korotkoff method to obtain this reading. One in four nurse practitioners used the Korotkoff method. When the ABPI values were calculated, the DINAMAP produced significantly higher median values than the Korotkoff (0.79 vs 0.72, p=0.003) and Doppler methods (0.79 vs 0.70, p<0.0001). The nurse had a higher median ABPI value of 0.76 compared with the doctor (0.71, p=0.01). CONCLUSION: This study shows that measurement of ABPI varies in different vascular units. The technique for ABPI measurement should be standardised.

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PubMed1999

Mortality rates following endovascular repair of abdominal aortic aneurysms.

PURPOSE: To present the perioperative and late mortality following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs). METHODS: Data were collected prospectively on 221 patients undergoing AAA EVR over a 4-year period (median 5-month follow-up). Patients were classified preoperatively as high risk with at least 1 of these features: serum creatinine > 150 micromol/L, ischemic heart disease or poor left ventricular function, respiratory function < 50% of predicted normal, ruptured or symptomatic AAA, contraindication to or failed open repair, and age > 80 years. RESULTS: One hundred forty (63.3%) patients were classified as high risk, the most common criterion being cardiac disease (n = 96, 68.6%). There were 25 (11.3%) deaths in the 30-day perioperative period, 22 (15.7%) in the high-risk group compared to 3 (3.7%) in the acceptable-risk group (p = 0.02). The most common causes of perioperative death were multisystem organ failure and myocardial infarction. A further 21 (9.5%) late deaths occurred, 16 (11.4%) in the high-risk group and 5 (6.2%) in the acceptable-risk group (p > 0.1). CONCLUSIONS: The mortality of patients at acceptable risk undergoing EVR compares with the best published series for conventional open AAA repair. The perioperative and late mortality in the high-risk patients are substantially higher.

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PubMed1998

A randomized, double-blind, placebo-controlled, crossover study to assess the immediate effect of sublingual glyceryl trinitrate on the ankle brachial pressure index, claudication, and maximum walking distance of patients with intermittent claudication.

PURPOSE: The goal of the present study was to assess the immediate effect of sublingual glyceryl trinitrate (GTN) in patients with intermittent claudication. METHODS: We conducted a randomized, double-blind, placebo-controlled crossover study. Inclusion criteria consisted of history of intermittent claudication, resting ankle brachial pressure index (ABPI) of 1.00 or less, a 20% or greater fall in ABPI after exercise, and maximum walking distance (MWD) of less than 250 m. Patients already receiving nitrates were excluded. In study 1, patients (n = 25) underwent a standard exercise test after randomization to receive either 800 microg of sublingual GTN or placebo. The postexercise ABPI was recorded. Then, the crossover portion of the study was performed. In study 2, patients (n = 22) had their claudication distance and MWD measured. They then were randomized to receive either GTN or placebo spray, and the exercise test was repeated, with the claudication distance and MWD recorded, followed by the crossover portion of the study. Statistical analysis was performed with the Wilcoxon matched pairs signed ranks test and the Mann-Whitney U test. RESULTS: In study 1, the median postexercise ABPIs for placebo and GTN were 0.29 and 0.36 (P =.0001). In study 2, the median claudication distance for both placebo and GTN groups was 70 m (P =.59). The median MWD for the placebo and GTN groups was 105 and 125 m (P =.0084) CONCLUSION: GTN can decrease the fall in ABPI after exercise and increase the MWD.

Administration, Sublingual↗
PubMed1998

Early complications of femorofemoral crossover bypass grafts after aorta uni-iliac endovascular repair of abdominal aortic aneurysms.

OBJECTIVE: The following procedures are the 3 main methods of endovascular repair (EVR) of abdominal aortic aneurysms (AAA): aorto-aortic bypass grafting, bifurcated bypass grafting, and aorta uni-iliac grafts. The latter method has the potential disadvantage of requiring an extra anatomic graft (ie, a femorofemoral crossover bypass graft) to maintain contralateral pelvic and limb perfusion. The aim of this study was to assess the complications associated with the femorofemoral crossover bypass graft after aorta uni-iliac EVR of AAA. METHOD: A prospective review was conducted of the complications attributable to the femorofemoral crossover bypass graft in 136 patients who underwent EVR of AAA with an aorta uni-iliac device. RESULTS: During a median follow-up of 7 months (range, 0 to 36 months), 4 patients had superficial wound infections that required antibiotic treatment and 2 patients had bypass graft infections. Nine hematomas developed: 7 (5%) groin hematomas (6 in patients with Dacron bypass grafts), 1 scrotal hematoma, and 1 perigraft hematoma. One bypass graft thrombus developed. CONCLUSION: The femorofemoral crossover bypass graft is a safe and a durable component of EVR of AAA with an aorta uni-iliac device. The results are similar to those with bifurcated devices.

Aorta, Abdominal↗
PubMed1996

Interaction between fibrillin genotype and blood pressure and the development of aneurysmal disease.

Debate as to whether abdominal aortic aneurysms (AAA) are caused by atherosclerosis or whether they have a strong genetic etiology continues. We have investigated the hypothesis that risk factors are likely to be strongest in patients with generalized aneurysmal disease. We screened 232 consecutive AAA patients for popliteal aneurysm and investigated cardiovascular and genetic risk factors in these patients. Ultrasonography demonstrated the presence of a popliteal aneurysm in 24 of 232 (10%) patients. Multivariate analysis identified four independent factors associated with popliteal aneurysm: age (p = 0.013), height (p = 0.017), triglyceride concentration (p = 0.009), and systolic blood pressure (p = 0.037). In the AAA patients a significant association of fibrillin-1 genotype was present, determined by a tandem repeat polymorphism, with both systolic and pulse pressure. The genotypes associated with the highest pressures were significantly more common among the patients with popliteal aneurysm, p = 0.03. Following these findings we investigated whether there was an association between fibrillin-1 genotype and blood pressure in a healthy population, 245 men aged 50-61 years. Again we found a significant association between fibrillin genotype and pulse pressure, p = 0.003. We suggest that a strong interaction occurs between fibrillin genotype and blood pressure which contributes to the development of aneurysmal disease.

Aging↗
PubMed1996

The Perth endoluminal bifurcated graft system--development and early experience.

The study aim was to develop a reliable endoluminal graft system that would enable the deployment of a bifurcated graft for infrarenal abdominal aortic aneurysms. A life-size plastic model was made of an abdominal aorta and iliac arteries, with a 50-mm infrarenal abdominal aortic aneurysm. This model was used to develop and test self-expanding graft systems, based on a barbed Gianturco stent and series of stainless-steel 'Z' stents within a woven Dacron graft. The bifurcated system developed involves a trouser graft with one long leg and one short. This graft-system is delivered through one femoral artery with deployment of the proximal aortic end infrarenally and the longer trouser leg within the ipsilateral common iliac artery. The short trouser leg is left hanging free within the distal end of the aneurysm cavity, just above the bifurcation. It is held open by a self-expanding stent and is cannulated from the contralateral femoral artery with a guide wire. A simple straight self-expanding stented graft is then deployed to extend this short trouser leg down into the common iliac artery, effectively creating an extension to the short leg. The graft system has been deployed in 21 patients with satisfactory exclusion of the aneurysm in 17 (81%). There has been one mortality and no conversion to open repair. All 17 aneurysms remain excluded at median follow-up of 30 (range 4-60) weeks. None of the four graft stents that leaked (two proximal and two distal) sealed spontaneously. Deployment of the uncovered Gianturco stent across the renal artery origins in 18 cases (85%) has not been associated with renal artery occlusion or deterioration in renal function at a median follow-up of 30 (range 4-60) weeks. The ability to deploy a bifurcated system increases the potential for endoluminal treatment of abdominal aortic aneurysm.

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PubMed1996

Unravelling the familial tendency to aneurysmal disease: popliteal aneurysm, hypertension and fibrillin genotype.

PURPOSE: To screen patients with abdominal aortic aneurysm for popliteal aneurysm and investigate cardiovascular and genetic risk factors associated with aneurysmal disease at more than one site (generalised aneurysmal disease). SUBJECTS, DESIGN AND SETTING: All patients referred to the Regional Vascular Surgical Service at Charing Cross Hospital with unruptured abdominal aortic aneurysm between 1989 and 1993 were screened for popliteal aneurysms, using ultrasonography. MAIN OUTCOME MEASURES: Palpation of a popliteal aneurysm or ultrasonographic detection of popliteal dilatation, where the ratio maximum popliteal fossa diameter/suprageniculate popliteal diameter was > or = 1.5, in relation to cardiovascular and genetic risk factors. RESULTS: Clinical examination detected popliteal aneurysms in only 11/232 patients (5%), but ultrasonography demonstrated the presence of popliteal aneurysm in a further 13 patients, 24/232 in total (10%). Multivariate regression identified four independent factors associated with popliteal dilatation disease: age (p = 0.046), height (p = 0.006), systolic hypertension (p = 0.037) and triglyceride concentration (p = 0.009). Generalised aneurysmal disease and systolic blood pressure were associated with polymorphic variation in the fibrillin-1 gene, but not with variations in the apolipoprotein B and type III collagen genes. CONCLUSIONS: Few patients with abdominal aortic aneurysm (10%) also have popliteal aneurysms: the risk of popliteal dilatation increases with age, height, systolic blood pressure, triglyceride concentration and fibrillin genotype. The strong interaction between fibrillin genotype and blood pressure may contribute to the familial tendency to aortic aneurysm.

Age Factors↗
PubMed1996

A self-expanding endoluminal graft for treatment of aneurysms: results through the development phase.

BACKGROUND: The results of two and a half years' experience of endoluminal treatment of aneurysmal disease (from March 1993 to December 1995) are reported. METHODS: The endoluminal grafts were individually made at Royal Perth Hospital. They are based on Dacron-covered stainless steel self-expanding 'Z' stents with Gianturco barbed stents (Cook Pty, Australia) for proximal anchorage for grafts within the aorta. RESULTS: Fourteen straight tube grafts (nine for aortic aneurysm, four for iliac aneurysm and one for subclavian aneurysm) and 24 bifurcate grafts were deployed; all were in patients considered high-risk for conventional repair. Seventy-two per cent of the straight tube grafts successfully excluded the aneurysm. The bifurcate grafts, in use since July 1994, successfully excluded the aneurysm in 88%. There were two delayed deaths from rupture after the grafts failed to exclude the aneurysms; two patients required conversion to open repair and survived; three patients have persistent endoleaks; and three of the bifurcate grafts subsequently occluded a graft limb but did not require further intervention. Ninety per cent of these complications occurred in the first half of the series (prior to January 1995). CONCLUSIONS: A learning and development curve was clearly apparent. The results thereafter compare favourably to those for open repair in similar high-risk groups, suggesting that these techniques hold promise for all patients with aneurysms.

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PubMed1995

Restorative proctocolectomy for Chagasic megacolon.

Chagas' disease is endemic in South America, affecting several million people. Megacolon, the commonest intestinal manifestation, causes severe constipation and usually requires surgery. We report a case which was treated by restorative proctocolectomy. We believe this to be a useful new technique in the treatment of this condition.

Adult↗
PubMed1994

Smoking and growth rate of small abdominal aortic aneurysms.

Smoking is an important risk factor for abdominal aortic aneurysm. Limiting the growth rate of small aneurysms has the potential to prevent them reaching a size at which surgical repair is considered. In 43 patients, with small aneurysms, growth rates were studied by serial ultrasound over 3 years. The median expansion rate of these small aneurysms was 0.13 cm per year. Growth rates were higher in those who continued to smoke (0.16 vs 0.09 cm per year in those who no longer smoked, p = 0.038). Higher growth rates were significantly correlated with the concentration of serum cotinine. Stopping smoking could reduce the growth rate of small abdominal aortic aneurysms.

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