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Biomedical subjects

B J Drew

Publications and source records attributed to B J Drew.

At least 73 records · Page 4Linked to original sources
PubMed1993

ST segment monitoring for coronary artery reocclusion following thrombolytic therapy and coronary angioplasty: identification of optimal bedside monitoring leads.

BACKGROUND: Bedside ST segment monitors analyze only one precordial lead and one, two or three limb leads. The precordial lead V1 (or V6 if V1 is not feasible) has been recommended for bedside monitoring because of its value in diagnosing cardiac rhythms with a wide QRS complex. Thus, the remaining lead choices for ST monitoring are limited to the six limb leads. PURPOSE: To determine which of the limb leads in conjunction with V1 or V6 provides the greatest sensitivity for myocardial ischemia, a study was undertaken. METHOD: A total of 30 vessel-unique ischemic episodes were analyzed prospectively using continuous 12-lead electrocardiographic recordings in patients with acute myocardial infarction (n = 2) and patients undergoing coronary angioplasty (n = 25). RESULTS: Ischemic changes were evident in all cases using the full 12-lead electrocardiogram. Right coronary artery-related ischemia was detected in all cases using a single-lead III or aVF. In the group as a whole, the best combinations were: V1 + aVF, V1 + III, V6 + III, and V6 + aVF. Two patients developed sudden coronary artery reocclusion in the cardiac care unit after successful angioplasty. In both, leads identified in the cardiac catheterization laboratory as sensitive for recording ischemia were excellent choices for detection of reocclusion in the cardiac care unit. CONCLUSIONS: 12-lead electrocardiogram recordings during coronary angioplasty balloon inflation provide excellent guidance for postprocedure lead selection decisions. The most valuable limb leads for detecting ischemia due to abrupt artery closure are leads III and aVF, either of which is more sensitive than the routinely monitored lead II. The precordial leads valuable for arrhythmia monitoring, V1 and V6, are seldom sensitive in detecting ischemia in these patients.

Adult↗
PubMed1993

Bedside electrocardiogram monitoring.

A recent national survey of critical care nurses reveals that the leads many nurses select to monitor their patients are diagnostically inferior to other available leads, and that lead placement often is inaccurate. This article reviews the best leads for electrocardiographic (ECG) monitoring, illustrates their accurate placement, and explains reasons for the dilemma in current practice. Questions relevant to practicing nurses are addressed, including 1) Is lead MCL1 as good as V1? 2) When is it appropriate to substitute lead MCL1 for V1? and 3) How important is it for electrodes to be placed exactly in specific anatomic locations? Finally, a case study is provided to illustrate how accurate monitoring can prevent misdiagnosis and resultant inappropriate therapy.

Critical Care↗
PubMed1993

ST segment monitoring for myocardial ischemia.

Many patients in the critical care unit (CCU) are at risk for myocardial ischemia and acute coronary artery reocclusion. The use of continuous ST segment monitoring detects transient and sustained ischemia, despite the absence of symptoms, more completely than rate and rhythm monitoring alone. The accuracy and sensitivity of the ST segment for detection of ischemia is dependent on the number and location of the electrocardiographic leads used in conjunction with the site of obstruction. Thus, when using ST segment monitoring for detection of ischemia, one of the most important decisions for the nurse to make is lead selection. In addition, both ischemic and nonischemic ST segment changes must be considered.

Critical Care↗
PubMed1992

Comparison of a vectorcardiographically derived 12-lead electrocardiogram with the conventional electrocardiogram during wide QRS complex tachycardia, and its potential application for continuous bedside monitoring.

Previous investigators published conflicting reports comparing a vectorcardiographically derived electrocardiogram (ECGD) with the conventional 12-lead one (ECG). Prior comparisons were obtained in adults during sinus rhythm, but never in patients with wide QRS complex tachycardia. The ECGD was evaluated during baseline rhythms in patients with varying cardiac diagnoses, and the diagnostic accuracy of the 2 methods was compared during 64 episodes of wide QRS complex tachycardia in 49 patients during cardiac electrophysiologic study. All leads of the 12-lead ECGD closely resembled the conventional ECG in baseline and tachycardia tracings, except leads V3 and V4. QRS voltages were less in the ECGD, resulting in an inability to detect left ventricular hypertrophy in one third of patients with that diagnosis. There was excellent agreement between the ECGD and ECG in diagnosing prior myocardial infarction (92%), ventricular preexcitation patterns (100%), bundle branch and fascicular blocks (100%), and axis deviation. The ECGD was equally as valuable as the ECG in the diagnosis of wide QRS complex tachycardia. There was perfect agreement between the 2 lead systems in application of the morphologic criteria differentiating supraventricular tachycardia with aberration from ventricular tachycardia in leads V1, V2 and V6, and for criteria requiring axis determination and measurement of RS intervals in the precordial leads. The ECGD tracings contained less muscle artifact during body movements (e.g., after direct-current defibrillation). In conclusion, the ECGD's close correlation with the ECG, and its technical superiority and simple 5 torso-positioned electrode configuration make it worth pursuing as an option for continuous bedside monitoring.

Adult↗
PubMed1991

Value of electrocardiographic leads MCL1, MCL6 and other selected leads in the diagnosis of wide QRS complex tachycardia.

To compare the modified precordial leads MCL1 and MCL6 with the conventional precordial leads V1 and V6 and assess the diagnostic accuracy of selected leads for continuous bedside electrocardiographic (ECG) monitoring, 121 wide QRS complex tachycardias were recorded from 92 patients during cardiac electrophysiologic study. As ascertained from intracardiac recordings, 86 tachycardias were ventricular and 35 were supraventricular with aberrant conduction. Early or late peaking of the predominant QRS deflection in lead MCL6 or V6 proved valuable in diagnosing wide complex tachycardia. An interval of less than or equal to 50 ms from the onset of the QRS complex to the predominant peak (or nadir) indicated supraventricular tachycardia; an interval of greater than or equal to 70 ms indicated ventricular tachycardia. The QRS complexes in leads MCL1 and MCL6 were comparable to those in leads V1 and V6 during sinus rhythm. Significant discrepancies in QRS configuration occurred between the modified and conventional precordial leads during ventricular tachycardia, especially between leads MCL1 and V1; however. these differences did not affect diagnostic accuracy. A single MCL1, V1, MCL6 or V6 lead was equally valuable in the diagnosis of wide complex tachycardia and far superior to a single lead II. A combination of leads (MCL1 + MCL6), (V1 + V6), (V1 + I + aVF) or (V1 + V6 + I + aVF) was superior to a single lead or the routinely monitored lead V1 + II combination.

Bundle-Branch Block↗
PubMed1991

MCL1 and MCL6 compared to V1 and V6 in distinguishing aberrant supraventricular from ventricular ectopic beats.

Use of V1 and V6 has been suggested for distinguishing aberrant supraventricular from ventricular ectopy. For two decades, "modified" leads MCL1 and MCL6 have been widely used as V1 and V6 substitutes for bedside monitoring, but their use has never been validated. To determine the value of MCL1 and MCL6, 81 morphologically distinct wide QRS ectopic beats were recorded from 46 patients during cardiac electrophysiological study. As determined by the His-bundle electrogram, 31 of the ectopics were aberrant supraventricular, 50 were ventricular. A new criterion, measurement of QRS onset to the predominant peak or nadir of the complex, was valuable in diagnosing wide complexes in MCL6 and V6. An interval of 50 msec or less predicted aberrant supraventricular ectopy; an interval of 70 msec or more predicted ventricular ectopy. There was agreement between the modified and conventional precordial leads regarding which QRS patterns were useful in distinguishing aberrant supraventricular from ventricular ectopy. A greater proportion of wide complexes in MCL1 and V1 exhibited patterns useful in making the diagnosis compared to MCL6 and V6. Using well-established criteria, the proportion of correct diagnoses that was made from individual leads was: MCL1 = 86%, V1 = 85%, MCL6 = 72%, V6 = 67%. The bedside leads (MCL1 and MCL6) were not statistically different in diagnostic accuracy from their conventional lead counterparts (V1 and V6); however, MCL1 and V1 were superior to MCL6 and V6. When the new criterion was added to make the diagnosis from MCL6 and V6, no difference in diagnostic accuracy was present between the four leads.

Bundle-Branch Block↗
PubMed1991

Accuracy of bedside electrocardiographic monitoring: a report on current practices of critical care nurses.

Diagnostic criteria for many arrhythmias can be observed from any monitoring lead; however, other important criteria are "lead specific," such as the diagnostic QRS patterns in V1 that aid in distinguishing ventricular tachycardia from supraventricular tachycardia with bundle branch block or aberration. Therefore, it makes a great deal of difference which leads are selected for bedside monitoring. Our purpose was to determine which leads nurses select for monitoring, and the accuracy of lead placement. From a random sample of nurses who were members of the American Association of Critical-Care Nurses, 302 returned a monitoring questionnaire. Average critical care experience was 8.5 years. Lead II was most often selected (74%) for single-channel monitoring; lead II plus V1 (or MCL1) were most often selected (87%) for dual-channel monitoring. Only 37% of nurses demonstrated proper technique for obtaining their single lead of choice; even fewer (13%) demonstrated proper technique for obtaining their dual leads of choice. These results suggest that misdiagnosis of arrhythmias such a wide complex tachycardia in monitored patients may be caused by inappropriate lead selection as well as inaccurate lead placement.

Arrhythmias, Cardiac↗
PubMed1991

Bedside electrocardiographic monitoring: state of the art for the 1990s.

Recent evidence indicates that misdiagnosis of cardiac arrhythmias is a common occurrence in critical care and telemetry units. The present article addresses the problem by reviewing electrocardiographic criteria for diagnosing the arrhythmias and ischemic conditions of major importance in the critically ill patient including wide QRS complex tachycardias, bundle branch blocks, and ST segment monitoring after thrombolytic therapy and balloon angioplasty. In addition, the advantages and disadvantages of various monitoring leads are discussed with recommendations regarding the most ideal leads for detecting these arrhythmias of interest. Finally, practical suggestions are offered for improving the quality of bedside electrocardiographic monitoring.

Angioplasty, Balloon, Coronary↗
PubMed1989

Cardiac rhythm responses. 2. Review of 22 years of nursing research.

To discover what questions nurses have been asking about cardiac rhythm responses, a literature search was conducted. A total of 57 nursing studies reported from 1964 through 1987 were identified. Research studies of cardiac rhythm responses could be grouped into four broad categories: (1) those that explored the phenomenon itself; (2) those that measured cardiac rhythm responses alone or in conjunction with other dependent variables as an index of another phenomenon such as fear, stress and anxiety, biologic (circadian) rhythms, pain severity and pain coping, sensory stimulation and overstimulation, fatigue, metabolic energy expenditure, and fetal well-being-fetal oxygen reserve; (3) those that measured cardiac rhythm responses to evaluate the safety or efficacy of various nursing interventions and routines; and (4) those that measured cardiac rhythm responses to evaluate recovery from acute myocardial infarction or cardiac surgery including evaluation of the success of cardiac rehabilitation programs. Four landmark studies that contributed new knowledge or changed practice are discussed. In addition, questions suggesting areas for future research are listed.

Electrocardiography↗
PubMed1989

Cardiac rhythm responses. 1. An important phenomenon for nursing practice, science, and research.

The human responses to actual or potential health problems that are of interest to nursing encompass physiologic, psychologic, and sociocultural responses. Measurement of cardiac rhythm responses provides a unique opportunity to look at the complex interplay of physiologic, emotional, and environmental factors at a particular time. A model depicting the relationships between cardiac rhythm responses and the central nursing domain concepts of individual, environment, health, transitions, and nursing therapeutics is presented. Measurement of cardiac rhythm responses provides an objective, quantifiable, noninvasive, inexpensive, readily accessible, reliable, and valid tool for measuring human responses. Study of the phenomenon holds promise for nursing practice, science, and research fostering links among the three. Study of cardiac rhythm responses will have direct applicability to practice with the potential for narrowing the research-practice gap. Moreover, study of the phenomenon will contribute to nursing knowledge and foster advancement of nursing science by the development of theory.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Chest pain is an unreliable measure of ischemia in men and women during PTCA.

OBJECTIVE: To investigate the differences between men and women in ischemia-induced pain, the amount of ST-segment deviation (the "ST deviation score"), and the relation between pain intensity and ST deviation score. DESIGN: Retrospective, comparative descriptive. SETTING: Cardiac catheterization laboratory of a large, urban, university-affiliated medical center with full cardiac services. PATIENTS: Adults who underwent percutaneous transluminal coronary angioplasty (PTCA) and had electrocardiographic (ECG) evidence of myocardial ischemia during balloon inflation. METHODS: Continuous 12-lead ECGs were recorded during balloon inflation in patients undergoing PTCA. Patients rated pain on a scale of 0 to 10. The total ST deviation score equaled baseline ECG ST minus maximal ST deviation; absolute deviations were totaled. Frequencies, measures of central tendency, or chi-square or t tests were used for data analysis with significance established at p < 0.05. RESULTS: There were no difference in the degree of chest pain between men and women during balloon inflation, nor was ST deviation score associated with pain in either gender. Pain intensity did not correlate with total ST deviation in men (r = 0.02) or women (r = -0.07). CONCLUSIONS: In this study, pain was a poor indicator of ischemia in both sexes during PTCA, and the degree of pain did not correlate with the magnitude of ST deviation. More than one third of men and more than one fourth of women experienced no chest pain during balloon inflation. Clinicians should consider continuous ST-segment monitoring and patient symptoms to monitor accurately for ischemia.

Adult↗
PubMedDate not supplied

Frequency of silent myocardial ischemia with 12-lead ST segment monitoring in the coronary care unit: are there sex-related differences?

BACKGROUND: Ischemia that occurs in the coronary care unit (CCU), whether symptomatic or silent, is associated with significant in-hospital and out-of-hospital complications. Studies have reported that more than 90% of ischemic episodes are silent in patients with unstable angina who are treated in the CCU with maximal medical therapy. Prior reports indicate that women complained more frequently of chest pain than men did. PURPOSE: The aim of this study was to compare the frequency of silent myocardial ischemia in men versus women with use of continuous 12-lead ST segment monitoring in the CCU. A secondary goal was to determine whether silent ischemia was associated with less ST segment deviation as compared with symptomatic ischemia. METHOD: Patients admitted for treatment of acute coronary syndrome in the CCU and who subsequently had 1 or more ischemic events during their monitoring period were selected for this analysis. All patients were continuously monitored (42.5 hours +/- 37.6) in the CCU with the EASI (Zymed Medical Instruments, Camarillo, Calif) 12-lead electrocardiogram (ECG) system that derives 12 leads with use of 3 information channels and 5 electrodes. RESULTS: Of 491 patients, 128 (91 men and 37 women) had at least 1 episode of transient myocardial ischemia. Men and women did not differ in their proportion of chest pain during ischemia (men 27% and women 21%, NS). For both men and women, ST segment deviation was significantly greater during symptomatic ischemia compared with silent ischemia. CONCLUSION: There are no sex-related differences in ischemic events in the CCU in regards to the variables of chest pain and ST magnitude. Therefore, because chest pain is not a reliable indicator of myocardial ischemia in the CCU, regardless of sex, patients should be adequately monitored for ischemic events.

Aged↗