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Biomedical subjects

B J Drew

Publications and source records attributed to B J Drew.

At least 55 records · Page 3Linked to original sources
PubMed1996

Computer versus manual measurement of ST-segment deviation.

Total ST scores (sum of absolute deviations in all 12 electrocardiographic [ECG] leads) have been used for research purposes to estimate total ischemic burden and to predict reperfusion after thrombolytic therapy. Computerized monitoring systems are capable of measuring ST deviation to the 10-microV level, whereas humans are incapable of such precise resolution. The purpose of this study was to compare computer versus manual ST scores in 12-lead ECGs exhibiting ischemia and to compare interrater reliability of manual measurements between two experts. A total of 58 subjects with 100 microV or more ST deviation in one or more leads during percutaneous transluminal coronary angioplasty balloon inflation were selected for analysis. ST measurements were made at J + 80 ms, using the isoelectric line as a reference, and summed across all 12 leads. Manual measurements were made to a minimum of 50 microV by two independent reviewers blinded to the computer scores. Total ST scores were compared using paired t-tests, and Pearson coefficients were used to test the correlations. A high correlation was observed between the manual and computer measurements (r = .96, P < .00) and between the two reviewers (r = .96, P < .00). A high degree of interrater reliability is possible with manual measurements of ST deviation. Computer measurements are consistently greater than manual measurements, presumably because humans "round down" to the nearest 50 microV. As such, computers may detect ischemia that is missed by humans. However, computer and manual measurements of ST deviation should not be mixed when used as a variable for research.

Angioplasty, Balloon, Coronary↗
PubMed1996

ST segment monitoring with a derived 12-lead electrocardiogram is superior to routine cardiac care unit monitoring.

BACKGROUND: Prior studies have shown that a derived 12-lead electrocardiogram with a simple electrode configuration is comparable with the standard electrocardiogram for arrhythmia analysis. METHODS: A prospective, comparative, within subjects design was used to compare the value of the derived 12-lead electrocardiogram with that of routine monitoring of leads V1 and II for detection of transient myocardial ischemia in 250 patients treated for unstable angina or myocardial infarction. RESULTS: During 11,532 hours of derived 12-lead ST segment monitoring, 55 (22%) of 250 patients had 176 episodes of ischemia. Of the 55 patients with ischemia, 75% reported no chest pain and 64% had no ischemic ST changes with routine monitoring leads. All five patients who developed angiographically confirmed abrupt reocclusion after percutaneous transluminal coronary angioplasty had ischemic ST changes with the derived electrocardiogram (sensitivity, 100%), compared with only two patients with routine monitoring (sensitivity, 40%). Serious complications occurred in 17% of angina patients with ischemic events compared to 3% of those without ischemia. Length of stay in the cardiac care unit was twice as long in angina patients who had ischemic events. In patients with acute myocardial infarction, ischemic events were not associated with a more complicated hospital course; however, length of stay in the cardiac care unit was longer in patients with recurrent ischemia. CONCLUSIONS: The findings show that derived 12-lead ST monitoring is superior to routine monitoring of leads V1 and II for detecting transient myocardial ischemia. ST monitoring of the derived 12-lead electrocardiogram may identify high-risk patients with unstable angina and provide prognostic information that would not be otherwise available from the usual clinical measures.

Adult↗
PubMed1996

ST segment deviation during myocardial ischemia: are there gender differences?

UNLABELLED: Prior research indicates that women have greater ST segment shifts at the time of percutaneous transluminal coronary angioplasty (PTCA) balloon inflation than men. However, ST deviation in men and women has not been compared during balloon occlusion of the same coronary vessel. METHODS: To determine whether there is a gender difference in degree of ST deviation, 12-lead electrocardiographic (ECG) recordings were made in 45 subjects undergoing PTCA (25 men, 20 women). A total ST score was obtained by summing absolute deviations across all 12 leads. All patients had single vessel coronary artery lesions in the proximal half of one of the major epicardial arteries without evidence of collateral circulation. RESULTS: There were no differences between men and women in terms of age, left ventricular hypertrophy, ejection fraction, or the Norris Coronary Prognostic Index, which combines age, history of infarction, and evidence of heart failure on chest X-ray. When comparing mean ST segment deviation in men and women, vessel to vessel, no gender differences were found. CONCLUSION: When matched for coronary vessel, men and women have comparable ST deviation patterns during coronary occlusion with PTCA balloon inflation. Therefore, detection of myocardial ischemia related to coronary occlusion with continuous ST segment monitoring should be equally sensitive in men and women.

Adult↗
PubMed1995

ECG criteria to distinguish between aberrantly conducted supraventricular tachycardia and ventricular tachycardia: practical aspects for the immediate care setting.

UNLABELLED: To reevaluate ECG criteria for distinguishing supraventricular tachycardia (SVT) with aberrant conduction from ventricular tachycardia (VT), 133 wide QRS tachycardias were recorded in patients undergoing invasive electrophysiological (EP) study. Surface ECG leads (standard 12-lead and MCL leads) were compared to EP recordings to provide a standard for correct diagnosis. Criteria from six studies were pooled to select QRS morphology agreed to be highly specific for SVT or VT (specificity > 90%). Some morphological criteria were modified to simplify analysis for the immediate care setting. RESULTS: Although the 12-lead ECG was useful in distinguishing aberrancy from VT, 13 tachycardias (10%) were misdiagnosed or could not be diagnosed. The MCL1 lead recorded clearly different QRS morphology than lead V1 in 40% of VT cases and was diagnostically inferior to V1. Most established criteria were highly specific for a diagnosis, but not very sensitive as individual criteria. Neither a QRS width of > 0.14 seconds nor a monophasic R wave pattern in lead V1 were valuable in diagnosing VT. CONCLUSIONS: In distinguishing SVT with aberrant conduction from VT: (1) Although the 12-lead ECG is valuable, about 1 in 10 wide QRS tachycardias defy differentiation; (2) tachycardias > 190 beats/min often do not exhibit unequivocal criteria with which to make a certain diagnosis; (3) multiple leads are required for accurate assessment of QRS width, presence of AV dissociation or VA block, QRS axis, and morphological criteria; and (4) the MCL1 lead cannot be substituted for V1 in the use of morphological criteria for VT.

Adolescent↗
PubMed1994

Electrocardiographic changes in critically ill adults during intrahospital transport.

Critically ill patients are frequently transported out of the intensive care unit (ICU) for diagnostic tests and procedures. Advanced diagnostic testing and increased patient acuity have influenced the level of nursing care required during intrahospital transport. Previous studies have documented deleterious patient outcomes during intrahospital transport, but none have evaluated twelve lead electrocardiograms (ECGs). Using a prospective design, this study sought to describe ECG changes during intrahospital transport. A secondary purpose was to describe the nursing implications of transporting the patients in this sample. A convenience sample of 29 critical care patients (14 cardiac, 8 neurological, 5 medical, 2 transplant) was selected from three ICUs at a university hospital. In addition to the standard, single bipolar lead monitor, patients were monitored with a portable, interpretative electrocardiograph with continuous 12 lead ST segment analysis. Results of this study indicate that cardiac events during intrahospital transport may go undetected because of current monitoring practices and the mechanics of transport.

Adult↗
PubMed1994

T wave alternans.

Explore the source record for details and available documents.

Electrocardiography↗
PubMed1993

Safety and efficacy of central intravenous bolus administration of adenosine for termination of supraventricular tachycardia.

OBJECTIVES: This study was done to quantify the dosing differences between central and peripheral adenosine administration for treatment of supraventricular tachycardia. BACKGROUND: Earlier studies that evaluated the safety and efficacy of adenosine primarily utilized a peripheral site of administration. Although it has been recommended that lower doses should be given centrally, dosing recommendations have not been provided. METHODS: Thirty adults with supraventricular tachycardia underwent invasive electrophysiologic study and were treated with central and peripheral intravenous administration of adenosine. Peripheral injections were administered through a venous catheter in an upper extremity and central infusions were accomplished by means of a catheter positioned in or near the right atrium. The site of administration was randomized and each subject received adenosine by both routes. Adenosine was administered every minute in increasing increments of 3, 6, 9 and 12 mg until the tachycardia terminated. Peripheral responses were compared with those obtained centrally. RESULTS: The minimal effective peripheral dose was distributed among the four doses: Tachycardia was terminated in 11 patients with 3 mg (37%), in 10 (33%) with 6 mg, in 4 (13%) with 9 mg and in 5 (17%) with 12 mg. In contrast, after central administration, 23 episodes of tachycardia (77%) were terminated with 3 mg, 6 (20%) with 6 mg and 1 (3%) with 9 mg; none required 12 mg. Lower doses of adenosine were more effective after central than after peripheral administration, with 63% of the subjects requiring a lesser dose. There was no difference between the two routes of drug administration in the incidence of side effects or transient arrhythmias at the time of tachycardia termination. CONCLUSIONS: Adenosine can be safely given centrally for termination of supraventricular tachycardia. The initial dose should be 3 mg.

Adenosine↗