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Biomedical subjects

G E Mead

Publications and source records attributed to G E Mead.

At least 19 recordsLinked to original sources
PubMed2002

Electrical cardioversion for atrial fibrillation and flutter.

BACKGROUND: Atrial fibrillation increases the risk of stroke, increases the risk of cognitive impairment, and adversely affects cardiovascular haemodynamics. Electrical cardioversion for atrial fibrillation has been in use since the 1960s; the rationale is that restoration of sinus rhythm improves cardiovascular haemodynamics, reduces the risk of stroke, and obviates the need for long-term anticoagulation. OBJECTIVES: To assess the effects of electrical cardioversion of atrial fibrillation or atrial flutter on the annual risk of thromboembolic events, strokes and mortality (primary outcomes measures), the rate of cognitive decline, quality of life, the use of anticoagulants and the risk of re-hospitalisation (secondary outcome measures) in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology. SEARCH STRATEGY: One reviewer searched the Cochrane Controlled Clinical Trials Register (2000 Issue 4), MEDLINE (1966 to December 2000), EMBASE (1980 to December 2000), CINAHL (1982 to November 2000) and proceedings of the American College of Cardiology (published in the Journal of the American College of Cardiology 1983 to 2000). Reference lists of articles were searched. Personal contact was made with experts in the field. A second reviewer handsearched proceedings of the British Cardiac Society (published in British Heart Journal (1980 to 1995) and in Heart (1995 to May 2001); proceedings of the European Congress of Cardiology and meetings of the Joint Working Groups of the European Society of Cardiology (published in European Heart Journal 1983-2000); scientific sessions of the American Heart Association (published in Circulation 1990-2000). SELECTION CRITERIA: Randomised controlled trial or controlled clinical trials of electrical cardioversion plus 'usual care' versus 'usual care' only, where 'usual care' included any combination of the following: anticoagulants, antiplatelet drugs and drugs for 'rate control', in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology. DATA COLLECTION AND ANALYSIS: It was planned to extract study data onto data extraction forms. The planned analysis was by the statistical package in RevMan. MAIN RESULTS: No completed randomised trials or controlled clinical trials of electrical cardioversion were found. Two ongoing trials were identified. REVIEWER'S CONCLUSIONS: There were no data from completed randomised controlled trials or controlled clinical trials to either support or refute the use of electrical cardioversion for atrial fibrillation. Randomised trials of electrical cardioversion are required.

Adult↗
PubMed2002

Severe ipsilateral carotid stenosis and middle cerebral artery disease in lacunar ischaemic stroke: innocent bystanders?

OBJECTIVES: Lacunar infarcts are thought to be mostly due to intracranial small vessel disease. Therefore, when a stroke patient with a relevant lacunar infarct does have severe ipsilateral internal carotid artery (ICA) or middle cerebral artery (MCA) disease, it is unclear whether the arterial disease is causative or coincidental. If causative, we would expect ICA/MCA disease to be more severe on the symptomatic side than on the asymptomatic side. Therefore, our aim was to compare the severity of ipsilateral with contralateral ICA and MCA disease in patients with lacunar ischaemic stroke. METHODS: We studied 259 inpatients and outpatients with a recent lacunar ischaemic stroke and no other prior stroke. We used carotid Duplex ultrasound and transcranial Doppler (TCD) ultrasound to identify ICA and MCA disease, and compared our results with previously published data. RESULTS: In our study, there was no difference between the severity of ipsilateral and contralateral ICA stenosis within individuals (median difference 0%, Wilcoxon paired data p=0.24, comparing severity of ipsilateral and contralateral stenosis). The overall prevalence of severe ipsilateral stenosis was 5%, and the prevalence of severe contralateral stenosis was 4% (OR 1.6, 95% CI 0.6, 4.8). There was no difference in the prevalence of ipsilateral and contralateral MCA disease. A systematic review of the other available studies strengthened this conclusion. CONCLUSION: Carotid stenosis in patients with a lacunar ischaemic stroke may be coincidental. Further studies are required to elucidate the causes of lacunar stroke, and to evaluate the role of carotid endarterectomy.

Carotid Stenosis↗
PubMed2000

Variability in Doppler ultrasound influences referral of patients for carotid surgery.

OBJECTIVE: Colour Doppler ultrasound is operator dependent, but it is unclear how much clinical impact this might have on patient referral for carotid endarterectomy. Our aim was to quantify the interobserver variability of Doppler ultrasound. METHODS: Consecutive patients attending for carotid Doppler ultrasound underwent two examinations on the same day, in random order, by two of three observers blind to each other's results. Severity of stenosis was assessed using standard velocity criteria and lesion appearance. RESULTS: A total of 189 patients were scanned (378 ICAs). Of the 134 ICAs scanned by observers 1 and 2, observer 1 classified 11 as 80-99% stenosis (operable), compared with nine by observer 2. Of the 206 ICAs scanned by observers 1 and 3, observer 1 classified 11 as 80-99% stenosis, compared with only five by observer 3. Of the 38 ICAs scanned by observers 2 and 3, observer 2 classified 2 as 80-99% stenosis compared with none by observer 3. Overall, clinical management would differ in 10/378 (3%) of ICAs, but in 10/22 (45%) of those considered operable by one of the three observers. CONCLUSION: There was clinically important interobserver variability in the assessment of ICA disease, which could result in serious errors if endarterectomy were performed on the basis of a single Doppler ultrasound.

Blood Flow Velocity↗
PubMed2000

How well does the Oxfordshire community stroke project classification predict the site and size of the infarct on brain imaging?

OBJECTIVES: The Oxfordshire Community Stroke Project (OCSP) classification is a simple clinical scheme for subdividing first ever acute stroke. Several small studies have shown that when an infarct is visible on CT or MRI, the classification predicts its site in about three quarters of patients. The aim was to further investigate this relation in a much larger cohort of patients in hospital with ischaemic stroke. METHODS: Between 1994 and 1997, inpatients and outpatients with ischaemic stroke were assessed by one of several stroke physicians who noted the OCSP classification. A neuroradiologist classified the site and extent of recent infarction on CT or MRI. RESULTS: Of 1012 patients with ischaemic stroke, 655 (65%) had recent visible infarcts. These radiological lesions were appropriate to the clinical classification in 69/87 (79%) patients with a total anterior circulation syndrome, 213/298 (71%) with a partial anterior circulation syndrome, 105/144 (73%) with a lacunar syndrome, and 105/126 (83%) with a posterior circulation syndrome. Overall, 75% of patients with visible infarcts were correctly classified clinically. If patients without a visible infarct did have an appropriate lesion in the brain (best case), the classification would have correctly predicted its site and size in 849/1012 (84%) patients, compared with only 492/1012 (49%) in the worst case scenario. CONCLUSION: The OCSP classification predicted the site of infarct in three quarters of patients. When an infarct is visible on brain imaging, the site of the infarct should guide the use of further investigations, but if an infarct is not seen, the OCSP classification could be used to predict its likely size and site.

Aged↗
PubMed2000

Relationship between pattern of intracranial artery abnormalities on transcranial doppler and Oxfordshire Community Stroke Project clinical classification of ischemic stroke.

BACKGROUND AND PURPOSE: The Oxfordshire Community Stroke Project (OCSP) devised a simple classification for acute stroke based on clinical features only, which is of value in predicting prognosis. We investigated whether the pattern of intracranial vascular abnormalities is related to the clinical syndrome. METHODS: Patients with acute ischemic stroke were classified by a stroke physician as having total or partial anterior circulation infarct (TACI or PACI, respectively), lacunar infarct (LACI), or posterior circulation infarct (POCI). Color-coded power transcranial Doppler was done whenever possible. Intracranial arterial velocities were compared in the 4 subtypes of ischemic stroke after adjustment for age and time to transcranial Doppler. RESULTS: Middle cerebral artery velocity was abnormal (hyperemia, reduced velocity, occlusion, or focal stenosis) in 38 of 69 TACIs (55%), 50 of 171 PACIs (29%), and 20 of 236 LACIs or POCIs (8%) (P<0.001). Velocity in the A1 segment of the anterior cerebral artery was reversed in 12 of 69 TACIs (17%), 20 of 171 PACIs (12%), and 8 of 236 LACIs or POCIs (3%) (P<0.001). Basilar artery velocity was abnormal in 8 of 121 POCIs (7%) compared with 5 of 355 (1%) of the other subtypes (P=0.005). Vertebral artery velocity was abnormal (reduced velocity, occlusion, stenosis) in 20 of 121 POCIs (17%) compared with 20 of 355 others (6%) (P=0.01). CONCLUSIONS: Intracranial arterial abnormalities were related to OCSP clinical subtype. Therefore, it is possible to stratify patients according to OCSP classification in trials of new treatments in which treatment effectiveness may depend on the underlying pattern of arterial pathology and before any arterial imaging is available.

Aged↗
PubMed1999

Cardioversion for atrial fibrillation: the views of consultant physicians, geriatricians and cardiologists.

BACKGROUND AND AIMS: Atrial fibrillation (AF) increases the risk of stroke and also has adverse haemodynamic consequences. Cardioversion of AF to sinus rhythm may obviate the need for long-term anticoagulation and improve cardiovascular haemodynamics, but is probably underused. We therefore investigated the views of hospital consultants about cardioversion for AF. METHODS: 336 Postal questionnaires were sent to all 186 consultant physicians, 54 cardiologists and 96 geriatricians in Scotland, followed by one reminder letter to non-responders. RESULTS: 71% Of questionnaires were returned. Cardiologists referred 18% of AF patients for cardioversion, while physicians referred 11% and geriatricians 5%. Cardiologists had better access to cardioversion facilities and were less likely to consider an enlarged left atrium and organic heart disease to be contra-indications to cardioversion. Anticoagulation was given for less than 3 weeks before cardioversion by 9% of cardiologists, 39% of physicians and 65% of geriatricians (P<0.001), and for less than 3 weeks after cardioversion by 17% of cardiologists, 45% of physicians and 47% of geriatricians (P = 0.7). SUMMARY: The wide variation in practice both between and within the different specialties suggests that consensus guidelines based on the best available evidence should be developed.

Atrial Fibrillation↗
PubMed1999

The influence of randomized trials on the use of anticoagulants for atrial fibrillation.

INTRODUCTION: Anticoagulants and anti-platelet drugs have been shown in randomized trials to reduce the risk of stroke in patients with atrial fibrillation (AF). We therefore investigated their use in patients known to be in AF before a stroke, transient ischaemic attack (either cerebral or ocular) or retinal artery occlusion to assess the influence of trials on clinical practice. METHODS: Inpatients and outpatients with acute stroke, transient ischaemic attack or retinal artery occlusion were prospectively identified by a stroke physician from 1990 to 1997. The presence or absence of AF before the vascular event, and prior use of anticoagulant and anti-platelet drugs were recorded at the time of the assessment and verified using information from general practitioner and hospital case notes. RESULTS: Of 1934 patients with stroke or retinal artery occlusion, 191 (10%) were in AF before their ischaemic event. Anticoagulants had been used in 40 (21%) of these, but only in 32 (2%) of the 1743 patients in sinus rhythm [odds ratio (OR) 14.2, 95% confidence interval (CI) 8.6-23.2]. Anti-platelet drugs had been used in 62 (32%) of those with AF compared with 500 (30%) of those in sinus rhythm (OR 1.2, 95% CI 0.9-1.64). Of the 161 patients in AF without contraindications to anticoagulants, only 36 (22%) were taking them. Although there was a statistically significant increase in anticoagulant use from 8% in 1990 to 23% in 1996, this could be explained solely by a fall in the age of the patients referred to our hospital. CONCLUSION: Anticoagulation is probably under-used in AF. We found no conclusive evidence that anticoagulation trials have influenced clinical practice. This raises issues about the dissemination and implementation of trial results.

Aged↗
PubMed1999

Can simple clinical features be used to identify patients with severe carotid stenosis on Doppler ultrasound?

OBJECTIVES: Carotid endarterectomy reduces the risk of stroke in symptomatic patients with severe ipsilateral carotid stenosis. Symptomatic patients should therefore undergo carotid Doppler imaging, but in some centres access to imaging is limited. It was therefore investigated whether simple clinical features alone or in combination could be used to identify patients with severe carotid stenosis, so that they could be referred preferentially for carotid imaging. METHODS: 1041 patients with acute stroke, cerebral or retinal transient ischaemic attacks, and retinal strokes admitted to Western General Hospital or seen in neurovascular clinics were assessed by a stroke physician. Their carotid arteries were investigated using colour Doppler imaging by a consultant neuroradiologist. Patients with primary intracerebral haemorrhage, total anterior circulation strokes, posterior circulation strokes, or posterior circulation transient ischaemic attacks were excluded because carotid surgery would be inappropriate. RESULTS: 726 patients were used in the analysis. Stepwise logistic regression showed that there were significant positive associations between severe carotid stenosis and an ipsilateral bruit, diabetes mellitus, and previous transient ischaemic attacks; and a negative association with lacunar events. The strategy with the highest specificity (97%) was "any three of these four features" but sensitivity was only 17%. The strategy with the highest sensitivity (99%) was to use one or more of the four features, but specificity was only 22%. CONCLUSION: None of the strategies identified all patients with severe carotid stenosis with a reasonable specificity. When access to carotid imaging is severely limited, simple clinical features are of some use in prioritising patients for imaging, but access to carotid imaging should be improved.

Aged↗
PubMed1999

Should computed tomography appearance of lacunar stroke influence patient management?

Patients with a lacunar stroke syndrome may have cortical infarcts on brain imaging rather than lacunar infarcts, and patients with the clinical features of a small cortical stroke (partial anterior circulation syndrome, PACS) may have lacunar infarcts on imaging. The aim was to compare risk factors and outcome in lacunar syndrome (LACS) with cortical infarct, LACS with lacunar infarct, PACS with cortical infarct, and PACS with lacunar infarct to determine whether the clinical syndrome should be modified according to brain imaging. As part of a hospital stroke registry, patients with first ever stroke from 1990 to 1998 were assessed by a stroke physician who assigned a clinical classification using clinical features only. A neuroradiologist classified recent clinically relevant infarcts on brain imaging as cortical, posterior cerebral artery territory or lacunar. Of 1772 first ever strokes, there were 637 patients with PACS and 377 patients with LACS who had CT or MRI. Recent infarcts were seen in 395 PACS and 180 LACS. Atrial fibrillation was more common in PACS with cortical than lacunar infarcts (OR 2.3, 95% confidence interval (95% CI) 0.9-5.5), and in LACS with cortical than lacunar infarcts (OR 3.9, 1.2-12). Severe ipsilateral carotid stenosis or occlusion was more common in PACS with cortical than lacunar infarcts (OR 3.5, 1.3-9.5); and in LACS with cortical than lacunar infarcts (OR 3.7, 1.1-12). In conclusion, patients with cortical infarcts are more likely to have severe ipsilateral carotid stenosis or atrial fibrillation than those with lacunar infarcts irrespective of the presenting clinical syndrome. Brain imaging should modify the clinical classification and influence patient investigation.

Brain↗
PubMed1998

Oral histoplasmosis: a case report.

We report a case of biopsy-proven histoplasmosis in an 81-year-old man with mouth ulcers. The initial infection was probably contracted whilst he was a prisoner of war in Sumatra, and was reactivated during intercurrent illness with congestive cardiac failure and oral corticosteroid treatment for idiopathic thrombocytopaenic purpura. Of particular note is the latent period of 50 years, and a positive cytoplasmic antineutrophil cytoplasmic antibody (cANCA) titre.

Adrenal Cortex Hormones↗
PubMed1998

Carotid disease in acute stroke.

BACKGROUND: the Oxfordshire Community Stroke Project (OCSP) devised a simple clinical classification for acute stroke which predicted mortality, functional recovery and patterns of recurrent stroke. We aimed to determine whether this could predict the presence of carotid disease and be used to select which patients with acute stroke should be referred for carotid imaging with a view to subsequent carotid endarterectomy. METHODS: we assessed patients with acute stroke admitted to seven hospitals over a 10-month period. Patients were classified according to the OCSP system and their carotid arteries investigated using portable continuous wave Doppler. Those with abnormal portable assessments had colour duplex Doppler imaging. RESULTS: of 305 patients with proven or probable cerebral infarction, severe (70-99%) ipsilateral carotid stenosis was found in 16 (16%) of the 101 with partial anterior circulation infarct (PACI), four (4%) of the 100 with total anterior circulation infarct (TACI), none of the 80 with lacunar infarct (LACI) and one (4%) of the 24 with posterior circulation infarct (POCI). Complete ipsilateral carotid occlusion was found in 25 (25%) of the TACI group, 11 (11%) of the PACI group, three (4%) of the LACI group and none of the POCI group. Severe carotid stenosis or occlusion was more common in the ipsilateral than the contralateral carotid artery for the TACI and PACI groups (chi2 P< 0.05), but there was no difference between ipsilateral and contralateral carotid disease in the LACI and POCI groups. If the OCSP classification is used to detect patients with 70-99% carotid stenosis, then the sensitivity is 76% and specificity is 70%. CONCLUSION: these findings suggest that ipsilateral carotid disease is an important cause of stroke for those with anterior circulation infarcts but not for those with LACI or POCI. Subjects with PACI should be referred for early carotid imaging to identify those with severe disease who may be suitable for elective carotid surgery.

Acute Disease↗
PubMed1997

Pilot study of carotid surgery for acute stroke.

BACKGROUND: Carotid endarterectomy is usually delayed for 2 months following an acute stroke, but the stroke may progress or a further stroke may occur. A randomized pilot study of urgent carotid surgery for acute stroke was undertaken to assess the feasibility of a definitive multicentre trial. METHODS: Seven Manchester hospitals referred patients with acute stroke (less than 7 days previously), defined according to the Oxfordshire Community Stroke Project classification The carotid arteries were examined by portable continuous-wave Doppler ultrasonography. Patients with more than 50 per cent carotid stenosis on portable Doppler ultrasonography underwent colour duplex Doppler imaging. Patients with more than 70-99 per cent carotid stenosis were randomized to urgent carotid surgery or best medical care. RESULTS: A total of 593 patients were assessed over 2 years. Of these, 414 had acute stroke, of whom 380 had probable cerebral infarction. Complete ipsilateral internal carotid artery occlusion was most common in patients with total anterior circulation infarcts (33 (28 per cent) of 117), whereas severe ipsilateral (70-99 per cent) stenosis was most common in partial anterior circulation infarcts (25 (20 per cent) of 128). Only 16 patients (one total and 15 partial anterior circulation infarcts) were fit enough for surgery and consented to randomization. CONCLUSION: A definitive trial of urgent carotid surgery would need to screen large numbers of patients but could focus on patients with partial anterior circulation infarcts.

Acute Disease↗
PubMed1997

Is there a role for carotid surgery in acute stroke?

INTRODUCTION: Carotid endarterectomy reduces the risk of stroke in patients with a history of minor ischemic stroke or transient ischaemic attacks and severe carotid stenosis, but the timing of surgery following acute stroke is controversial. Urgent carotid surgery in acute stroke may reduce the risk of early stroke recurrence due to further emboli from the diseased carotid, or may improve neurological recovery by improving cerebral blood flow to the ischaemic penumbra. METHODS: We identified from the literature patients undergoing carotid surgery in acute stroke using a Medline search and identifying references from these sources. RESULTS: Over 2000 patients were identified from the literature who underwent acute carotid surgery. Heterogeneous groups of patients were recruited, with no control patients treated medically in the majority of the studies. Mortality and morbidity was highly variable and depended primarily on the initial severity of the neurological deficit, with lower mortality in patients with minor neurological deficits. CONCLUSIONS: The role of carotid surgery in acute stroke is uncertain. A multicentre randomised controlled trial is now required to assess the value of acute carotid surgery.

Acute Disease↗
PubMed1996

Neutrophil activation in jugular venous blood during carotid endarterectomy.

OBJECTIVES: Neutrophils may play an important role in cerebral ischaemia. We investigated whether neutrophil activation can be detected in cerebral venous blood during the mild cerebral hypoxia and reperfusion that occurs during carotid cross clamping and declamping for endarterectomy. DESIGN, SETTING AND MATERIALS: The ipsilateral jugular bulb was cannulated at operation in 16 patients undergoing carotid endarterectomy. Blood was taken immediately prior to and 30 seconds following internal carotid cross clamping; then immediately prior to, 30 s and 2 m following declamping. Blood was also taken from a peripheral vein in the foot. Intracerebral oxygen saturation (CsO2) was measured continuously by near infrared cerebral spectroscopy. Neutrophil activation was measured by flow cytometric detection of fluorescence to hydrogen peroxide in unstimulated cells and phorbol myristate acetate stimulated cells, and expressed as mean fluorescent intensity (MFI). OUTCOME MEASURES: Neutrophil activation and cerebral oxygenation. MAIN RESULTS: CsO2 fell from 68% (95% Confidence interval 64%-72%) to 63% (59%-68%) following carotid cross clamping (p < 0.05, repeated measures analysis of variance). This recovered slightly during the cross clamp period to 64% but only returned to preclamp levels following declamping (p > 0.05). Neutrophil hydrogen peroxide generation by stimulated neutrophils rose significantly from 0.79 mean fluorescent intensity (0.53-1.19) to 1.46 (0.98-2.20) but no there was no further rise following cross clamp release. There was no significant neutrophil activation in the peripheral samples. CONCLUSIONS: These results indicate that even mild cerebral hypoxia is associated with priming of neutrophils in cerebral venous blood.

Aged↗