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QJM: monthly journal of the Association of Physicians 04/2011; 104(4):365-6. · 2.33 Impact Factor
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ABSTRACT: The 80-lead Body Surface Map (BSM) is a diagnostic tool utilised by clinicians for the diagnosis of myocardial infarction (MI) at our centre. The optimum number and placement of leads on the BSM is uncertain. We used Genetic Algorithm (GA) analysis to determine a reduced lead system for the optimal diagnosis of MI. 1106 cases presenting to our centre with ischaemic type chest pain (576 ST Segment Elevation MI, 244 Atypical ECG and 286 Non-MI) were recorded using the 80-lead BSM. A GA was developed to determine a subset of reduced number of leads, with their associated anatomical position within the 80-lead BSM system, while maintaining sensitivity and specificity for MI diagnosis. The GA was run on two separate occasions (Run A and Run B) and the output compared with the 80-Lead BSM. Run A produced a 24 lead system. The sensitivity and specificity for MI diagnosis was 86.40% and 97.55% respectively. Received Operator Characteristic (ROC) curve c-statistic was 0.805. Run B produced a 21 lead system with sensitivity and specificity of 84.84% and 98.25% respectively. ROC curve c-statistic was 0.811. This compares favourably with the 80 lead BSM (sensitivity 90%, specificity 92%, ROC c-statistic 0.850).
Computing in Cardiology, 2010; 10/2010
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B M Glover,
S J Walsh,
C J McCann,
M J Moore,
G Manoharan,
G W N Dalzell,
A McAllister,
B McClements,
D J McEneaney,
T G Trouton,
T P Mathew, A A J Adgey
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ABSTRACT: To compare the efficacy and safety of an escalating energy protocol with a non-escalating energy protocol using an impedance compensated biphasic defibrillator for direct current cardioversion of atrial fibrillation (AF).
This prospective multicentre randomised trial enrolled 380 patients (248 male, mean (SD) age 67 (10) years) with AF. Patients were randomised to either an escalating energy protocol (protocol A: 100 J, 150 J, 200 J, 200 J), or a non-escalating energy protocol (protocol B: 200 J, 200 J, 200 J). Cardioversion was performed using an impedance compensated biphasic waveform. First-shock success was significantly higher for those randomised to 200 J than 100 J (71% vs 48%; p<0.01) and for patients with a body mass index (BMI) >25 kg/m(2) (75% vs 44%; p = 0.01). In patients with a normal BMI there was no significant difference in first-shock success. There was also no significant difference between subsequent shocks or overall success. The use of a non-escalating protocol (protocol B) resulted in fewer shocks but with a higher cumulative energy. There was no difference in duration of procedure, amount of sedation administered or post-shock erythema between the groups.
First-shock success was significantly higher, particularly in patients with a BMI >25 kg/m(2), when a non-escalating initial 200 J energy was selected. The overall success, duration of procedure and amount of sedation administered, however, did not differ significantly between the two protocols.
Heart (British Cardiac Society) 07/2008; 94(7):884-7. · 4.22 Impact Factor
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ABSTRACT: To determine the diagnostic accuracy of advanced medical priority dispatch system (AMPDS) software used to dispatch public access defibrillation first responders to out-of-hospital cardiac arrests (OHCA).
All true OHCA events in North and West Belfast in 2004 were prospectively collated. This was achieved by a comprehensive search of all manually completed Patient Report Forms compiled by paramedics, together with autopsy reports, death certificates and medical records. The dispatch coding of all emergency calls by AMPDS software was also obtained for the same time period and region, and a comparison was made between these two datasets.
A single urban ambulance control centre in Northern Ireland.
All 238 individuals with a presumed or actual OHCA in the North and West Belfast Health and Social Services Trust population of 138 591 (2001 Census), as defined by the Utstein Criteria.
The accurate dispatch of an emergency ambulance to a true OHCA.
The sensitivity of the dispatch mechanism for detecting OHCA was 68.9% (115/167, 95% confidence interval (CI) 61.3% to 75.8%). However, the sensitivity for arrests with ventricular fibrillation (VF) was 44.4% (12/27) with sensitivity for witnessed VF of 47.1% (8/17). The positive predictive value was 63.5% (115/181, 95% CI 56.1% to 70.6%).
The sensitivity of this dispatch process for cardiac arrest is moderate and will constrain the effectiveness of Public Access Defibrillation (PAD) schemes which utilise it.
controlled-trials.com ISRCTN07286796.
Heart (British Cardiac Society) 04/2008; 94(3):349-53. · 4.22 Impact Factor
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Journal of Human Hypertension 01/2008; 21(12):969-72. · 2.80 Impact Factor
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ABSTRACT: To determine the epidemiology of out of hospital sudden cardiac death (OHSCD) in Belfast from 1 August 2003 to 31 July 2004.
Prospective examination of out of hospital cardiac arrests by using the Utstein style and necropsy reports. World Health Organization criteria were applied to determine the number of sudden cardiac deaths.
Of 300 OHSCDs, 197 (66%) in men, mean age (SD) 68 (14) years, 234 (78%) occurred at home. The emergency medical services (EMS) attended 279 (93%). Rhythm on EMS arrival was ventricular fibrillation (VF) in 75 (27%). The call to response interval (CRI) was mean (SD) 8 (3) minutes. Among patients attended by the EMS, 9.7% were resuscitated and 7.2% survived to leave hospital alive. The CRI for survivors was mean (SD) 5 (2) minutes and for non-survivors, 8 (3) minutes (p < 0.001). Ninety one (30%) OHSCDs were witnessed; of these 91 patients 48 (53%) had VF on EMS arrival. The survival rate for witnessed VF arrests was 20 of 48 (41.7%): all 20 survivors had VF as the presenting rhythm and CRI < or = 7 minutes. The European age standardised incidence for OHSCD was 122/100,000 (95% confidence interval 111 to 133) for men and 41/100,000 (95% confidence interval 36 to 46) for women.
Despite a 37% reduction in heart attack mortality in Ireland over the past 20 years, the incidence of OHSCD in Belfast has not fallen. In this study, 78% of OHSCDs occurred at home.
Heart (British Cardiac Society) 04/2006; 92(3):311-5. · 4.22 Impact Factor
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ABSTRACT: This paper describes the development of a model to assess the distribution of response times for mobile volunteers of a public access defibrillation (PAD) scheme in Northern Ireland. Using parameters based on a trial period, the model predicts that a PAD volunteer would arrive before the emergency medical services (EMS) to 18.8% of events to which they are paged in a given year period. This is in agreement with what has actually been observed during the trial period (where volunteers have actually reached 15% of events before the EMS), and thus assisting validation of the model. Results from this model illustrate how ongoing volunteer commitment is key to the success of the scheme
Computer-Based Medical Systems, 2006. CBMS 2006. 19th IEEE International Symposium on; 02/2006
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ABSTRACT: A comprehensive appraisal was undertaken on behalf of the British Cardiac Society and the Royal College of Physicians of London to assess the use of clopidogrel in acute coronary syndromes. The appraisal was submitted to the National Institute for Clinical Excellence (NICE) in August 2003 and contributed to the development of the recently published guidelines for the use of clopidogrel in acute coronary syndromes. The submission to NICE and more recent publications evaluating the use of clopidogrel are reviewed.
Heart (British Cardiac Society) 10/2005; 91(9):1135-40. · 4.22 Impact Factor
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ABSTRACT: The Inverse ECG problem is ill-conditioned and its solution requires a relatively high computing effort. Additional constraints are required in order to obtain a stable solution. A method is proposed in which the solution of the inverse ECG problem is approached in the frequency domain, taking advantage of the assumption that propagation delays may be ignored and the quasi-periodicity of ECG. In this method usual Tikhonov zero-order constraints are applied to the amplitudes of the signals for a selected frequency domain. This method ensures faster solutions that are spatially and temporally well behaved. Calculation of epicardial electrograms is compared to a basic method.
Computer-Based Medical Systems, 2005. Proceedings. 18th IEEE Symposium on; 07/2005
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Heart (British Cardiac Society) 02/2005; 91(1):118-25. · 4.22 Impact Factor
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Heart (British Cardiac Society) 01/2005; 90(12):1493-8. · 4.22 Impact Factor
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ABSTRACT: A novel device for transvenous atrial defibrillation with a biphasic rectangular pulse waveform, with instant power supplied through a radio-frequency energy-transfer link in a short air gap of up to 18 mm, has been investigated and is briefly described here. Previous waveform assessments, have suggested that a biphasic and asymmetric (second phase at 50% amplitude) pulse waveform of energy discharge is of particular clinical interest. Hence, a safety study upon the haemodynamic effects of such a novel waveform for atrial defibrillation, was carried out on 6 animal models (pigs), at energy levels of 3 J and 5 J. The results demonstrated relatively small and reversible effects on the haemodynamics and the novel waveform was comparable in effect to a conventional, capacitor-based (with RC exponential decay), biphasic waveform. Also, an assessment of the device output performance for various air gap distances is presented.
Devices, Circuits and Systems, 2004. Proceedings of the Fifth IEEE International Caracas Conference on; 12/2004
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Electronics Letters 01/2004; 39(25):1789- 1790. · 0.96 Impact Factor
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ABSTRACT: To test prospectively depolarisation and repolarisation body surface maps (BSMs) for mirror image reversal, which is less susceptible to artefact, in patients with acute ischaemic-type chest pain, and to compare these BSM criteria with previously published 12 lead ECG criteria.
An 80 lead portable BSM system was used to map patients presenting with acute ischaemic-type chest pain and a 12 lead ECG with left bundle branch block (LBBB). Acute myocardial infarction (AMI) was defined by serial cardiac enzymes. Each 12 lead ECG was assessed by the criteria of Sgarbossa et al and Hands et al for diagnosis of AMI. Depolarisation and repolarisation BSMs were assessed for loss of mirror image reversal of QRS with ST-T isointegral map patterns and a change in vector angle from QRS to ST-T outside 180+/-15 degrees -findings typically seen in LBBB with AMI.
Of 56 patients with chest pain and LBBB, 18 had enzymatically confirmed AMI. Patients with loss of BSM image reversal were significantly more likely to have AMI (odds ratio 4.9, 95% confidence interval 1.5 to 16.4, p = 0.007). Loss of BSM image reversal was significantly more sensitive (67%) for AMI than either 12 lead ECG method (17%, 33%) albeit with some loss in specificity (BSM 71%, 12 lead ECG 87%, 97%). Patients with AMI compared with those without AMI had a greater mean change in vector angle outside the normal range (180+/-15 degrees ), particularly between QRS isointegral and ST60 isopotential (the potential 60 ms after the J point at each electrode site) BSMs (19 degrees v 9 degrees, p = 0.038). Loss of image reversal and QRS-ST60 vector change outside 180+/-15 degrees had 61% sensitivity and 82% specificity for AMI (odds ratio 7.0, 95% confidence interval 2.0 to 24.4, p = 0.001).
BSM compared with the 12 lead ECG improved the early diagnosis of AMI in the presence of LBBB.
Heart (British Cardiac Society) 10/2003; 89(9):998-1002. · 4.22 Impact Factor
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ABSTRACT: To compare prospectively the impact of pre-hospital care by a physician-staffed mobile coronary care unit with patients managed initially in-hospital, all with acute myocardial infarction.
This was a single centre registry of consecutive patients (n=750) admitted with acute myocardial infarction to the coronary care unit and cardiology wards of the Royal Victoria Hospital, Belfast between 1998 and 2001. For the 750 patients, in-hospital mortality was 11% and was significantly lower for those managed pre-hospital (8% vs 13%, P=0.04): patients who received fibrinolytic therapy (n=474), the in-hospital mortality was significantly lower in the pre-hospital group (7% vs 13%, P=0.02). Those managed pre-hospital had significant reduction in the median delay times (25th, 75th percentiles) from onset of symptoms to call for help 1.0 (0.5, 2.2) vs 2.0 (0.9, 6.0) h, P<0.001, from call for help to receiving fibrinolytic therapy 1.0 (0.8, 1.5) vs 1.8 (1.2, 2.5) h, P<0.001 resulting in a shorter pain-to-needle time for fibrinolytic therapy 2.3 (1.5, 3.8) vs 4.0 (2.6, 7.2) h, P<0.001. For all patients, older age, haemodynamic indicators on admission (hypotension, higher heart rate, heart failure) and managed by the in-hospital route were significant independent variables for an adverse in-hospital mortality. Although for patients aged >or=75 years no statistical significant reduction in mortality occurred for those managed pre-hospital (P=0.051), nevertheless patients in this age group first treated pre-hospital who received fibrinolytic therapy had a significantly lower mortality than those first treated in-hospital (21% vs 43%, P=0.02).
Consecutive patients with acute myocardial infarction seen and managed initially out-of-hospital by a physician-staffed mobile coronary care unit had significantly lower in-hospital mortality.
European Heart Journal 01/2003; 24(2):161-71. · 10.48 Impact Factor
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European Heart Journal 11/2002; 23(19):1490-1. · 10.48 Impact Factor
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ABSTRACT: Patients with Q waves and T-wave inversion are generally at a later stage of the infarction process than patients without these changes. Our aim was to investigate whether a single assessment of electrocardiographic parameters at presentation would predict the proportion of myocardium salvageable by thrombolytic therapy.
Electrocardiographic algorithms to calculate the potential and final infarct size have been developed and allow the proportion of myocardium salvageable with therapy to be calculated. This was measured in 146 patients with acute myocardial infarction who had angiography at a median of 91 min after streptokinase. The relationship between myocardial salvage and the electrocardiographic parameters at presentation (Q waves, T-wave inversion, quantitative ST segment changes, and the initial QRS score), was examined together with the 90-min angiographic parameters (TIMI flow grade and collateral grade), clinical parameters (haemodynamics and age), and time to therapy. Parameters that correlated with myocardial salvage included the initial QRS score (r=-0.56, P<0.0001), Q wave grade (r=-0.36, P<0.0001), number of leads with ST depression (r=0.28, P<0.001), maximum ST depression (r=0.27, P<0.01), T-inversion grade (r=-0.26, P<0.01), and TIMI flow grade at 90 min (r=0.21, P<0.02). The time from symptom onset to thrombolytic therapy did not correlate with salvage (r=-0.09). On multivariate analysis, only the initial QRS score and T-inversion grade on the initial electrocardiogram were independent predictors of salvage (multivariate r using both variables combined=0.57, P<0.001).
The QRS score and T-wave inversion grade on the presenting electrocardiogram provide important information in predicting myocardial salvage. These parameters may help triage patients to appropriate therapies.
European Heart Journal 04/2002; 23(5):399-404. · 10.48 Impact Factor
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European Heart Journal 02/2002; 23(1):3-5. · 10.48 Impact Factor
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ABSTRACT: The detection of coronary heart disease leading to sudden death remains one of the greatest challenges in contemporary society. The advancements in new thrombolytic drugs offer significant potential far improved management of patients developing an acute myocardial infarction outside hospital. However, new diagnostic devices are now required to increase the sensitivity of detection beyond that achievable with the standard 12 lead ECG.
Intelligent Information Systems Conference, The Seventh Australian and New Zealand 2001; 12/2001
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ABSTRACT: Atrial fibrillation (AF) is one of the most common sustained cardiac arrhythmias found. Its treatment requires the use of a synchronised electrical shock or drug therapy. This paper describes a new form of electrical defibrillator that employs a two-part, transdermal RF transformer to couple an on-off keyed 7.2 MHz pulse to an implanted, passive receiver; this, in turn, delivers a unipolar DC shock to the heart. Factors influencing the transformer's design are discussed and results from axial and lateral primary/secondary coil displacement trials presented. In animal studies, cardioversion was 100% successful with pulses of 100 V amplitude and 10 ms width. The implant is battery-free, which makes it an attractive and inexpensive alternative for the treatment of AF.
Intelligent Information Systems Conference, The Seventh Australian and New Zealand 2001; 12/2001
