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Biomedical subjects

I B Menown

Publications and source records attributed to I B Menown.

17 recordsLinked to original sources
PubMed2001

ST depression only on the initial 12-lead ECG: early diagnosis of acute myocardial infarction.

AIMS: To compare the diagnostic ability of the 12-lead ECG with body surface mapping for early detection of acute myocardial infarction in patients presenting with ST depression only on the 12-lead ECG. METHODS AND RESULTS: Fifty-four consecutive patients with chest pain <24 h and ST depression were recruited. A 12-lead ECG and 80-lead body surface map were recorded at presentation from which univariate and multivariate prediction models of acute myocardial infarction were developed. Patients were randomly divided into a training-set and a validation-set. Acute myocardial infarction occurred in 16/30 training-set and 8/24 validation-set patients. Univariate prediction of acute myocardial infarction by the 12-lead ECG, based on the depth or numbers of leads with ST depression, was not improved by assessment of ST elevation outside the conventional 12 leads using body surface mapping. The optimum multivariate 12-lead ECG model developed in training-set patients (six ST depression variables) had poor sensitivity (38%) although good specificity (81%) for acute myocardial infarction when tested prospectively in validation-set patients. In contrast, the optimum body surface mapping model developed in training-set patients (three isointegral or isopotential variables) achieved high sensitivity (88%) whilst maintaining good specificity (75%) for acute myocardial infarction when tested prospectively in validation-set patients. CONCLUSION: Body surface mapping, when compared with the 12-lead ECG, may improve the early diagnosis of acute myocardial infarction in patients presenting with chest pain and ST depression only on the 12-lead ECG.

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PubMed2001

Suspected angina pectoris: a rapid-access chest pain clinic.

We prospectively evaluated a rapid-access chest pain clinic in terms of clinical diagnoses, outcomes, morbidity and mortality at 3 months follow-up in patients, and cost-effectiveness. All patients seen at the clinic from February 1999 to December 2000 were assessed. Referring doctors indicated the management they would have provided had the clinic been unavailable, to allow a cost-effectiveness analysis. Overall, 709 patients were referred, 471 (66%) from General Practitioners, 212 (30%) from Accident and Emergency doctors and 26 (4%) from other sources. All had recent onset, or increasing frequency of ischaemic-type chest pain (excluding those with suspected myocardial infarction or rest chest pain angina). Fifty-one (7%) had acute coronary syndromes, 119 (17%) had stable ischaemic heart disease, 144 (20%) had possible ischaemic heart disease, and 395 (56%) were considered to have non-ischaemic symptoms. Some 70% of patients were seen within 24 h. Only 57 patients (8%) were admitted. Had the clinic been unavailable, 160 patients would have been admitted. Out-patient cardiology appointments were arranged for 116 patients (16%), and 429 patients (60%) were discharged directly. Follow-up data at 3 months were obtained from 565/567 eligible patients (99.6%). No major cardiac events (death/myocardial infarction) occurred in those with non-ischaemic chest pain. There were five deaths (including one due to cancer) and three patients had a myocardial infarction (event rate 1%). There were eleven readmissions for angina: six were in patients with acute coronary syndromes, and four of these six were awaiting revascularization. The estimated net saving was pound 58/patient. A rapid-access chest pain clinic offers a prompt, safe and cost-effective service in a challenging group of patients.

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PubMed2000

Noninvasive assessment of reperfusion after fibrinolytic therapy for acute myocardial infarction.

Assessment of reperfusion by the 12-lead electrocardiogram (ECG) or biochemical markers is limited by suboptimal sensitivity and/or specificity. Body surface mapping (BSM) improves the spatial sampling of the 12-lead ECG. Serial 12-lead ECGs and 64-lead anterior BSMs were recorded from 67 patients with acute myocardial infarction undergoing coronary angiography 90 minutes after fibrinolytic therapy. ECG-1 and BSM-1 were recorded before/shortly after therapy (median 18 minutes). ECG-2 and BSM-2 were recorded after the 90-minute angiogram (median 30 minutes). The maximum ST elevation on ECG-1 was noted and > or = 30% ST resolution on ECG-2 was taken to represent partial/complete reperfusion. Patients were randomly divided into a training set and validation set. Isointegral and isopotential ST-T variables from BSMs of training-set patients were compared with Thrombolysis In Myocardial Infarction (TIMI) trial flow using discriminant analysis to identify which variables best classified reperfusion. Reperfusion (TIMI 2/3 flow) occurred in 32 of 34 training-set patients and in 29 of 33 validation-set patients. In the training set, > or = 30% ST resolution correctly classified reperfusion with 72% sensitivity (23 of 32) and 50% specificity (1 of 2). In the validation set, > or = 30% ST resolution classified reperfusion with 59% sensitivity (17 of 29) and 50% specificity (2 of 4). In comparison, a model containing 24 BSM variables correctly classified all training-set patients, and when prospectively tested in the validation-set, correctly classified 28 of 29 patients who achieved reperfusion (97% sensitivity) and all 4 patients who failed to reperfuse (p = 0.035). In conclusion, BSM is more useful than the 12-lead ECG for noninvasive assessment of reperfusion after fibrinolytic therapy for acute myocardial infarction.

Analysis of Variance↗
PubMed2000

Early diagnosis of right ventricular or posterior infarction associated with inferior wall left ventricular acute myocardial infarction.

Right ventricular (RV) or posterior infarction associated with inferior wall left ventricular acute myocardial infarction (AMI) has important therapeutic and prognostic implications. However, RV and posterior chest leads in addition to the 12-lead electrocardiogram are required for accurate detection. Body surface mapping (BSM) has greater spatial sampling and may further improve inferior wall AMI classification. Consecutive patients with chest pain lasting <12 hours were assessed to identify those with AMI and > or =0.1 mV ST elevation in > or =2 contiguous inferior leads of the 12-lead electrocardiogram (bundle branch block or left ventricular hypertrophy excluded). A 12-lead electrocardiogram, RV leads (V(2)R, V(4)R), posterior chest leads (V(7), V(9)), and a BSM were recorded. From each BSM, the 12 electrodes overlying the RV region (regional RV map) and 10 electrodes overlying the posterior wall (regional posterior map) were assessed for ST elevation. Infarct size was estimated by serial cardiac enzymes. AMI occurred in 173 of 479 patients. Of the 62 patients with inferior wall AMI, ST elevation > or =0.1 mV occurred in 26 patients (42 in V(2)R or V(4)R compared with 36 patients (58%) in > or =1 electrode on the regional RV map (p = 0.0019). ST elevation > or =0.1 mV occurred in 1 patient (2%) in V(7) or V(9) compared with 17 patients (27%) in > or =1 electrode on the regional posterior map (p = 0.00003). ST elevation > or =0.05 mV occurred in 6 patients (10%) in V(7) or V(9) compared with 22 patients (36%) in > or =1 electrode on the regional posterior map (p = 0.00003). Patients with ST elevation on regional RV and/or posterior maps had a trend toward larger infarct size (mean peak creatine kinase 1,789+/-226 vs. 1,546+/-392 mmol/L; p = NS). Thus, BSM, when compared with RV or posterior chest leads, provides improved classification of patients with inferior wall AMI and RV or posterior wall involvement.

Body Surface Potential Mapping↗
PubMed2000

Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarction.

AIMS: The optimum definition of ST elevation for diagnosis of acute myocardial infarction, with respect to both the minimum height and the minimum numbers of leads, is unknown. Furthermore, only 50% of patients with acute myocardial infarction present with ST elevation. We thus quantified the sensitivity and specificity of different ST elevation criteria for diagnosis of acute myocardial infarction, and determined whether models incorporating multiple QRST features in addition to ST elevation, could improve detection of acute myocardial infarction. METHODS AND RESULTS: The study population comprised 1190 subjects: 1041 consecutive patients presenting with chest pain (335 with acute myocardial infarction) and 149 controls without chest pain. Subjects were randomly divided into a training set (587) and a validation set (603). ECG prediction models for acute myocardial infarction incorporating different ST elevation criteria and/or additional QRST features (Q waves, ST depression, T wave inversion, bundle branch block, axes deviations, and left ventricular hypertrophy) were developed in training set patients using forward stepwise multiple logistic regression. Models were then prospectively tested in the validation set patients. The optimum ST elevation model (based on > or =1 mm ST elevation in > or = 1 inferior/lateral leads, or > or =2 mm ST elevation in > or =1 anteroseptal leads) correctly classified 83.1% of subjects (55.8% sensitivity, 94. 0% specificity). The choice of ST elevation definition had marked influence on the sensitivity (45.4-68.6%) and specificity (81.2-98. 1%) for diagnosis of acute myocardial infarction. The addition of multiple QRST variables only marginally improved overall classification but did result in high specificity (92.6-96.1%). CONCLUSION: Different definitions of 'significant' ST elevation led to marked variations in sensitivity and specificity for diagnosis of acute myocardial infarction. Multiple QRST features in addition to ST elevation only marginally improved overall classification.

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PubMed2000

Improving the ECG classification of inferior and lateral myocardial infarction by inversion of lead aVR.

OBJECTIVE: To assess whether the use of inverted lead aVR (-aVR) would improve the classification of acute inferior or lateral myocardial infarction presenting with ST elevation. DESIGN: Observational study. The presence of >/= 1 mm ST elevation in lead -aVR (derived by manual assessment of ST depression in conventional lead aVR) was determined by a single investigator, blinded to patient outcome. PATIENTS: 173 consecutive patients with chest pain for </= 12 hours and ST elevation of >/= 1 mm in inferior leads (II, III, aVF) or lateral leads (I, aVL, V5, V6), excluding those with anterolateral ST elevation. MAIN OUTCOME MEASURE: Incidence of ST elevation in lead -aVR in patients with inferior or lateral ST elevation, or both. RESULTS: ST elevation in lead -aVR was present in 25 of 136 patients (18%) with inferior but no lateral ST elevation (indicating greater superior involvement) and in three of 11 patients (27%) with lateral but no inferior ST elevation (indicating greater inferior involvement). ST elevation in lead -aVR bridged the gap between inferior and lateral ST elevation in 15 of 25 (60%) patients with inferior and lateral chest lead (V5/V6) ST elevation, and in all patients with inferior and lateral limb lead (I/aVL) ST elevation. The presence of ST elevation in lead -aVR was associated with a larger infarct size as defined by median peak creatine kinase on serial sampling: 1780 v 987 mmol/l; p = 0.021. CONCLUSIONS: Use of lead -aVR improves the ECG classification of acute inferior or lateral acute myocardial infarction and thus may be useful as part of the routine 12 lead ECG assessment of such patients.

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PubMed1999

Determinants of coronary blood flow after thrombolytic administration. TIMI Study Group. Thrombolysis in Myocardial Infarction.

OBJECTIVES: This study evaluated the determinants of coronary blood flow following thrombolytic administration in a large cohort of patients. BACKGROUND: Tighter residual stenoses following thrombolysis have been associated with slower coronary blood flow, but the independent contribution of other variables to delayed flow has not been fully explored. METHODS: The univariate and multivariate correlates of coronary blood flow at 90 min after thrombolytic administration were examined in a total of 2,195 patients from the Thrombolysis in Myocardial Infarction (TIMI) 4, 10A, 10B and 14 trials. The cineframes needed for dye to first reach distal landmarks (corrected TIMI frame count, CTFC) were counted as an index of coronary blood flow. RESULTS: The following were validated as univariate predictors of delayed 90-min flow in two cohorts of patients: a greater percent diameter stenosis (p < 0.0001 for both cohorts), a decreased minimum lumen diameter (p = 0.0003, p = 0.0008), a greater percent of the culprit artery distal to the stenosis (p = 0.03, p = 0.02) and the presence of any of the following: delayed achievement of patency (i.e., between 60 and 90 min) (p < 0.0001 for both cohorts), a culprit location in the left coronary circulation (left anterior descending or circumflex) (p = 0.02, p < 0.0001), pulsatile flow (i.e., reversal of flow in systole, a marker of heightened microvascular resistance, p = 0.0003, p < 0.0001) and thrombus (p = 0.002, p = 0.03). Despite a minimal 16.4% residual stenosis following stent placement, the mean post-stent CTFC (25.8 +/- 17.2, n = 181) remained significantly slower than normal (21.0 +/- 3.1, n = 78, p = 0.02), and likewise 34% of patients did not achieve a CTFC within normal limits (i.e., <28 frames, the upper limit of the 95th percent confidence interval previously reported for normal flow). Those patients who failed to achieve normal CTFCs following stent placement had a higher mortality than did those patients who achieved normal flow (6/62 or 9.7% vs. 1/118 or 0.8%, p = 0.003). CONCLUSIONS: Lumen geometry is not the sole determinant of coronary blood flow at 90 min following thrombolytic administration. Other variables such as the location of the culprit artery, the duration of patency, a pulsatile flow pattern and thrombus are also related to slower flow. Despite a minimal 16% residual stenosis, one-third of the patients treated with adjunctive stenting still have a persistent flow delay following thrombolysis, which carries a poor prognosis.

Angioplasty, Balloon, Coronary↗
PubMed1998

Body-surface map models for early diagnosis of acute myocardial infarction.

The standard 12-lead ECG is only 50% sensitive for the detection of acute myocardial infarction (AMI). The majority of leads for optimal classification of AMI probably lie outside the area covered by the 6 precordial leads. Thus, body-surface mapping (BSM) may be more helpful, as a larger thoracic area is sampled. We recorded 64-lead anterior BSMs in 635 patients with chest pain suggestive of AMI and abnormal electrocardiograms (ECGs), and 125 controls without chest pain. Of the 635 patients, 325 had AMI according to World Health Organization (WHO) criteria (203 presenting with ST segment elevation, and 122 with nondiagnostic ECG), and 310 had an "abnormal ECG but not AMI." QRS and ST-T isointegrals and variables describing map shape were derived. Subjects were randomly allocated to a training set (63 controls, 321 patients) and a validation set (62 controls, 314 patients). Multiple logistic regression was used in the training set to identify which variables gave best discrimination between groups. A model with these variables was then tested prospectively in the validation set. In stage 1 (all subjects), controls were compared with patients. In the training set, a model containing 21 variables classified 58/63 controls (specificity 92%) and 316/321 patients (sensitivity 98%). In the validation set, the model classified 48/62 controls (specificity 77.4%) and 302/314 patients (sensitivity 96%). In stage 2 (studying patients only), patients with AMI were compared with patients who had an abnormal ECG-not AMI. In the training set, a model containing 28 variables classified 132/165 patients (sensitivity 80%) with AMI and 134/156 patients (specificity 86%) with an abnormal ECG-not AMI. In the validation set, the model classified 123/160 patients (sensitivity 77%) with AMI and 131/154 patients (specificity 85%) with an abnormal ECG-not AMI. Combining results of both stages in a two-step algorithm gave an overall classification in the training set of controls 92%, abnormal ECG-not AMI 84%, AMI 80%, and in the validation set of controls 77%, abnormal ECG-not AMI 82%, AMI 74%. Thus, in conclusion, when compared with the 12-lead ECG, BSM models results in higher sensitivity and specificity for detection of AMI, particularly in patients presenting with chest pain and nondiagnostic ECG changes. The use of BSM models in such patients, may lead to the earlier detection of AMI and appropriate administration of fibrinolytic therapy and/or anti-platelet agents.

Body Surface Potential Mapping↗
PubMed1997

Community-acquired lower respiratory tract infection: implementation of an antibiotic protocol.

Enthusiastic formulation of clinical guidelines continues to increase but although theoretical difficulties in guideline implementation have been recognised, little attention has been paid to their effectiveness in everyday clinical practice. The introduction of a protocol for empirical treatment of lower respiratory tract infection (PETRI) to an acute medical take-in unit in Belfast is described. Early involvement of all relevant staff, preparation of user-friendly flow charts, and imaginative publicity, resulted in an initial implementation rate of 75%. The role of implementation as a significant rate-limiting step in the audit cycle is emphasised.

Anti-Bacterial Agents↗
PubMed1993

Perinatal outcome and antenatal care in a black South African population.

The relationship between perinatal outcome and antenatal care was investigated at King Edward VIII Hospital, Durban, by a case control retrospective study of pregnancy records in 165 perinatal deaths and 156 infants surviving the perinatal period. 82% of the mothers of live infants had booked for antenatal care compared with only 60% of those who experienced a perinatal death. Hospital booking was associated with a higher infant birthweight. For those who booked earlier there was no reduction in total perinatal mortality or the stillbirth:neonatal death ratio, and many of the mothers of highest risk failed to book. This suggests that the better perinatal outcome in booked mothers may have been secondary to the type of mother who chose to book, rather than the actual antenatal care. To help reduce perinatal mortality, methods must be employed which reach those mothers who are most likely to fail to book.

Birth Weight↗
PubMed1992

Retro-pharyngeal liposarcoma.

We present a case of extensive recurrence of a retro-pharyngeal liposarcoma following surgical removal 18 years previously. The surgery and pathology are discussed, and management strategies of head and neck liposarcomas are reviewed.

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