PubMed Health⌕ Search

Biomedical subjects

Galen S Wagner

Publications and source records attributed to Galen S Wagner.

At least 19 recordsLinked to original sources
PubMed2006

Improvement of the detection of myocardial ischemia thanks to information technologies.

BACKGROUND: The standard 12-lead ECG remains one of the basic investigations for the early detection and assessment of acute coronary syndromes. It is easy to perform, anywhere and anytime, and can be digitally transmitted within minutes to an emergency medical service for remote advice and triage. But the conventional ST-segment deviation criteria are of limited diagnostic accuracy. The purpose of this study is to investigate how much the use of computerized ECG techniques based on the measurement of the serial spatiotemporal ECG changes could improve the detection accuracy of transmural myocardial ischemia. METHODS: We considered the serial changes of continuous 12-lead ECGs of 90 patients undergoing elective percutaneous coronary angioplasty (PTCA) recorded during balloon inflation as an experimental model of ECG changes induced by coronary artery occlusion. The spatiotemporal ECG changes were measured according to the CAVIAR method and assessed by multivariate discriminant analysis in reference to serial changes of control recordings and standard ECG criteria. RESULTS: The diagnostic accuracy of the CAVIAR criteria for ischemia detection was 97%, with sensitivity of 98% and specificity of 96%, whereas the diagnostic accuracy of the conventional ST-segment criteria was 74%, with sensitivity of 60% and specificity of 88%. The increase of overall performance was obtained for all the occlusion locations. CONCLUSIONS: Computer-assisted quantitative serial ECG analysis, taking into account the spatiotemporal changes of the QRS and T waves, would provide the physician with additional information for significantly improving the detection of transmural myocardial ischemia.

Diagnosis, Computer-Assisted↗
PubMed2006

Detection of acute ischemia from the EASI-derived 12-lead electrocardiogram and from the 12-lead electrocardiogram acquired in clinical practice.

ST-segment measurements in the standard 12-lead electrocardiogram (ECG) of patients with acute coronary syndromes are crucial for these patients' management. Our objective was to determine whether the 12-lead ECG derived from the 3-lead EASI system can attain a level of diagnostic performance similar to that of the Mason-Likar (ML) 12-lead ECG acquired in clinical practice (CP) by paramedics and emergency department technicians. Using 120-lead body surface potential maps recorded before and during balloon inflation angioplasty from 88 patients (divided into "responders" and "nonresponders"), and electrode placement data from 60 applications of precordial leads in CP, we generated for the "nonischemic" and "ischemic" states of each patient the following lead sets: the ML 12-lead ECG, the EASI-derived 12-lead ECG, and 60 sets of 12-lead CP ECGs. We extracted ST deviations at J + 60 milliseconds, summed them for all 12 leads of each lead set to obtain SigmaST, and, by using the bootstrap method, determined the mean sensitivity and specificity for recognizing the "ischemic" state at various thresholds of SigmaST. Results were displayed as receiver operating characteristics, and the area under these curves (AUC) +/- SE was used as the measure of diagnostic performance. AUC +/- SE for all patients were ML ECG, 0.66 +/- 0.03; EASI ECG, 0.64 +/- 0.03; and CP ECG, 0.67 +/- 0.03. Corresponding results for responders only were 0.81 +/- 0.04 for ML ECG, 0.78 +/- 0.04 for EASI ECG, and 0.81 +/- 0.04 for CP ECG. The differences between the AUCs for the different lead sets were not significant (P > .05). Thus, the EASI-derived 12-lead ECG is as good for detecting acute ischemia as is the 12-lead ECG acquired in CP.

Electrocardiography↗
PubMed2006

The value of both ST-segment and QRS complex changes during acute coronary occlusion for prediction of reperfusion-induced myocardial salvage in a canine model.

BACKGROUND: Analysis of ST-segment elevation for assessment of patients with suspected acute coronary occlusion is in widespread use for diagnostic and prognostic purposes. In this study, changes in the QRS complex also were analyzed to determine if these changes that are seldom used clinically can provide additional prognostic information. An acute coronary occlusion canine model, in which direct measurements of myocardial salvage were made, was used to assess whether ST-segment and QRS complex changes during coronary occlusion yielded independent estimates of the amount of salvage provided by reperfusion with arterial blood. METHODS AND RESULTS: Continuous electrocardiographic recordings were obtained from 14 study dogs undergoing a 90-minute period of coronary artery occlusion in which the severity of the ischemia during the occlusion was estimated at 10 and 45 minutes by microsphere injections. After 3 hours of reperfusion, the myocardium at risk and postmortem infarct size was measured. Myocardial salvage correlated inversely with both ST-segment elevation (r = -0.85; P < .0001), and QRS complex prolongation (r = -0.72; P = .003). When dogs were paired so that they had equal amounts of ST elevation but differed with respect to the presence of QRS prolongation, less myocardial salvage was found in those with QRS prolongation. The independent value of QRS prolongation was supported further by the observation that presence of QRS prolongation resulted in a loss of the highly significant correlation between ST elevation and salvage (r = -0.60; P = .2). CONCLUSIONS: High magnitudes of ST elevation are correlated significantly with less myocardial salvage. Moreover, for a given magnitude of ST elevation, the presence of concurrent QRS prolongation is associated with even less myocardial salvage.

Animals↗
PubMed2006

Effectiveness of prehospital wireless transmission of electrocardiograms to a cardiologist via hand-held device for patients with acute myocardial infarction (from the Timely Intervention in Myocardial Emergency, NorthEast Experience [TIME-NE]).

Percutaneous coronary intervention for patients with ST-segment elevation myocardial infarction (STEMI) decreases morbidity and mortality if performed within the first 2 hours of symptom onset. However, the American College of Cardiology/American Heart Association guideline for percutaneous coronary intervention door-to-balloon time (<90 minutes) in patients with STEMI is a infrequently accomplished goal. This study enrolled 277 patients with STEMI who were self-transported or transported by emergency medical services to NorthEast Medical Center for primary percutaneous coronary intervention. This study tested the hypothesis that prehospital wireless transmission of an electrocardiogram to a cardiologist's hand-held device results in shorter emergency department door-to-reperfusion time. A comparison was made between patients whose electrocardiogram was successfully transmitted during the intervention phase with (1) patients transported by the emergency medical services in the preintervention, (2) patients self-transported in the intervention phase, and (3) patients whose wireless transmission failed in the intervention phase. During the preintervention phase (2001 to 2003), 48 patients were enrolled. During the intervention phase (2003 to 2005), the following patients were enrolled: 101 self-transported patients, 24 patients with successful electrocardiographic transmission, and 19 patients for whom transmission failed. The median door-to-reperfusion time for patients with successful electrocardiographic transmission was 50 minutes, which was significantly shorter than a preintervention time of 101 minutes (p <0.0001), an intervention phase self-transport time of 96 minutes (p <0.0001), and a failed transmission time of 78 minutes (p <0.0001). In conclusion, prehospital wireless electrocardiographic transmission to a cardiologist's hand-held device significantly decreased emergency department door-to-reperfusion time, thus achieving the American College of Cardiology/American Heart Association guideline for patients with STEMI.

Aged↗
PubMed2006

Reduced high-frequency QRS components in electrocardiogram leads facing an area of the heart with intraventricular conduction delay due to bundle branch block.

BACKGROUND: The mechanisms underlying high-frequency QRS components (HF-QRS) are incompletely understood. One theory is that HF-QRS are related to the conduction velocity of the heart. The purpose was to test this hypothesis by comparing HF-QRS in patients with left or right bundle branch block (LBBB and RBBB, respectively) to those in healthy subjects and in patients with ischemic heart disease (IHD). METHODS: Twenty-two patients with LBBB, 19 patients with RBBB, 63 normal subjects, and 64 patients with IHD were included. Twelve-lead electrocardiograms were analyzed in the frequency interval 150 to 250 Hz. RESULTS: The study showed reduced HF-QRS in patients with LBBB compared with healthy subjects and patients with IHD. The difference, however, was small in lead V(1) and V(2). In patients with RBBB, no differences in HF-QRS could be detected except in few leads; among those is lead V(1). CONCLUSION: The results support the theory that HF-QRS are related to the conduction velocity of the heart.

Adolescent↗
PubMed2006

Comparison of ST-segment deviation to scintigraphically quantified myocardial ischemia during acute coronary occlusion induced by percutaneous transluminal coronary angioplasty.

This study compared ST-segment changes during acute coronary artery occlusion with measurements of ischemia by myocardial scintigraphy. Forty patients who were referred for elective prolonged percutaneous transluminal coronary angioplasty underwent 12-lead electrocardiographic recording before the procedure (baseline) and continuously during the entire balloon inflation (occlusion). For each patient, the summed ST-segment deviation was calculated as the maximal absolute difference, elevation or depression, between baseline and occlusion recordings in all 12 leads. Each patient underwent 2 myocardial scintigraphies, 1 with technetium-99m sestamibi injected during the balloon inflation and 1 on the following day as a control study. Ischemia that was induced by balloon occlusion was quantified in terms of extent and severity. Results for the entire study group showed that summed ST deviation correlated with extent (r = 0.59, p < 0.0001) and severity (r = 0.61, p < 0.0001) of ischemia. The location of maximal ST deviation differed for the 3 arteries. For occlusion of the left anterior descending artery, maximal ST deviation was elevated in lead V3. For occlusion of the left circumflex artery, maximal ST deviation was depressed in lead V2. Occlusion of the right coronary artery caused ST elevation in lead III and ST depression in lead V2. In conclusion, this study demonstrated a significant correlation between summed ST deviation and myocardial ischemia during coronary occlusion that is induced by percutaneous transluminal coronary angioplasty.

Acute Disease↗
PubMed2006

Usefulness of quantitative baseline ST-segment elevation for predicting outcomes after primary coronary angioplasty or fibrinolysis (results from the DANAMI-2 trial).

The DANAMI-2 trial showed a 40% decrease in the composite end point with primary coronary angioplasty versus fibrinolysis. This result was primarily driven by a decrease in reinfarction, with no significant difference in mortality or stroke rates. The objective of this study was to determine the prognostic value of the sum ST-segment elevation (SigmaST) on baseline electrocardiography in patients who were randomized to receive primary coronary angioplasty versus fibrinolysis. In the DANAMI-2, 1,450 patients had baseline ST-segment deviation measurements and were assigned to quartiles according to SigmaST: 0 to 6.5, 7.0 to 9.5, 10.0 to 14.5, and 15.0 to 70.5 mm. The composite and component end-point rates at 30 days were determined for each quartile and chi-square for trend statistic was used to compare end-point rates across quartiles of SigmaST. The composite end point occurred more often with increasing SigmaST (p = 0.05). With regard to component end points, only mortality increased significantly with SigmaST (p = 0.03), whereas reinfarction and stroke rates did not. By multivariate analysis, only SigmaST and age were independent predictors of mortality. The relative benefit of primary coronary angioplasty was similar for all SigmaST quartiles. In conclusion, the magnitude of SigmaST correlates with increased mortality at 30 days, thus driving the composite end point rate. Regardless of SigmaST, patients had a lower composite end-point rate with primary coronary angioplasty than with fibrinolysis.

Aged↗
PubMed2006

A cooperative network of trained sites for the conduct of a complex clinical trial: a new concept in multicenter clinical research.

BACKGROUND: The purpose of this report is to present a model of physicians in full-time clinical practice participating as investigators in multicenter clinical trials, sponsored by a pharmaceutical or medical device company. METHODS: This gas-exchange substudy was conducted as a pilot study to establish the feasibility of the 10-member EXERcise testing group of the Duke University Cooperative Cardiovascular Society (EXERDUCCS) consortium to perform a complex multicenter trial using cardiopulmonary exercise testing. An active interchange of information was established involving the principal investigator for the substudy, a dedicated full-time project coordinator, a medical director of the overall EXERDUCCS network site, the project coordinator for the sponsor, and all the participating EXERDUCCS investigators and coordinators. RESULTS: The sponsor set as a goal of enrollment of 6 subjects per site, and 8 of the 10 sites met this goal. As a result of the successful enrollment and completion of the study and substudy by the EXERDUCCS sites, the sponsor subsequently increased the payment stipends to the sites to compensate for the extra work and expense incurred. CONCLUSIONS: This cooperative experience accomplished several goals: (1) it allowed a complex clinical trial to be successfully completed in a time frame which would not have been possible using only single unconnected sites; (2) it educated the physician-investigators (and their personnel) in exercise cardiopulmonary; and (3) it prepared the sites for future clinical trials involving this methodology.

Angiotensin Receptor Antagonists↗
PubMed2006

Diagnostic conclusions from the EASI-derived 12-lead electrocardiogram as compared with the standard 12-lead electrocardiogram in children.

BACKGROUND: Fewer electrodes on more easily located places would facilitate electrocardiogram (ECG) recording. To investigate the possibility of simplifying ECG recording in children, we compared the diagnostic conclusions when interpreting standard versus EASI-derived 12-lead ECGs. Our hypothesis was that the variation of the interpretation of standard versus EASI-derived 12-lead ECGs was not greater than the intrareader variation of the interpretation of standard ECGs. METHODS: The study included 221 children. The 2 lead systems were recorded simultaneously. Two experienced pediatric cardiologists interpreted the ECGs. First, the reader interpreted a set of 221 ECGs with randomly allocated standard and EASI-derived 12-lead ECGs. Next, the reader interpreted the complementary ECG set without having access to the first set. Finally, the reader reinterpreted the standard ECGs from 98 children. RESULTS: The variation of the interpretation of standard versus EASI-derived 12-lead ECGs was only slightly larger than the intrareader variation of the interpretation of standard ECGs. CONCLUSIONS: For most of the electrocardiographic diagnoses, the conclusions from EASI-derived 12-lead ECGs were similar to those from standard ECGs. These findings support the suggestion that the EASI lead system is a potential alternative to the standard ECG in children.

Adolescent↗
PubMed2006

The prognostic value of the admission and predischarge electrocardiogram in acute coronary syndromes: the GUSTO-IIb ECG Core Laboratory experience.

BACKGROUND: Prior research suggests that patients may be entered into clinical trials with different electrocardiographic (ECG) findings than specified by study protocol criteria; the extent and impact of this variability in a large-scale trial have not been previously described. METHODS: We evaluated the relationship between case report form (CRF) categorization of the admission ECG and a Core Laboratory and subsequent outcome in a retrospective analysis of a trial of patients with acute ischemia and a broad spectrum of ECG changes (the GUSTO-IIb trial). RESULTS: In 11,037 patients with CRF information and an interpretable ECG, there was agreement in 89.1% of ST-elevation and 81.9% of non-ST-elevation cases. Among patients designated as having no ST elevation on the CRF, 1-year mortality rates were significantly higher in the subgroup of patients with Core Laboratory-determined ST elevation as compared with those where both the CRF and Core Laboratory classification were in agreement (8.8% vs 6.8%, P = .0093). Among patients designated as having ST elevation by the CRF, 1-year mortality rates were similar in both the subgroup of patients with and without Core Laboratory agreement (7.7% vs 8.2%, P = .72). CONCLUSIONS: These findings have important implications for clinicians in routine practice because even a simple evaluation (presence or absence of ST elevation) on the admission ECG was often discordant and was associated with adverse clinical outcome.

Aged↗
PubMed2006

The failure of years of experience with electrocardiographic transmission from paramedics to the hospital emergency department to reduce the delay from door to primary coronary intervention below the 90-minute threshold during acute myocardial infarction.

INTRODUCTION: Emergency medical services (EMS), hospital emergency departments, and cardiologists have taken steps to reduce time to reperfusion therapy by implementation of aggressive acute myocardial infarction treatment and triage protocols. Data indicate that significant myocardial salvage requires reperfusion within 2 hours, and the current American College of Cardiology guideline is 90 minutes after hospital emergency department admission. MATERIALS AND METHODS: To minimize delays in time to reperfusion in an urban-rural North Carolina County, Guilford County EMS and the Moses Cone Hospital have collaborated to implement transmission of EMS electrocardiographs (ECGs) to the emergency department. The study population included 92 patients who were transported by EMS and received primary coronary intervention during the second, third, and fourth years after initiation of this intervention in 1993. RESULTS: The median time from symptom onset to the initial ECG was 77 minutes. There was an additional 23 minutes between the availability of this ECG and the arrival of the patient at the emergency department. In the first year of the intervention, the time from hospital arrival to percutaneous coronary intervention was 80 minutes. In years 2 through 4, they were 93, 85, and 94 minutes, respectively. In 2003, 10 years after the intervention, the time from hospital arrival to percutaneous coronary intervention was 113 minutes. CONCLUSION: Initial gains in the time from hospital arrival to percutaneous coronary intervention, attributed to acquisition of the ECG in the prehospital setting, were not sustained over 10 years.

Angioplasty, Balloon, Coronary↗
PubMed2006

Determination of the ability of high-frequency ECG to estimate left ventricular mass in humans, determined by magnetic resonance imaging.

BACKGROUND: Previous studies have shown a significantly higher correlation between left ventricular mass index (LVMi) and high-frequency QRS components (HF-QRS) than between LVMi and QRS amplitudes in the standard frequency range in rabbits. The purpose of the present study was to compare ECG measurements from standard and high-frequency ranges with left ventricular mass (LVM) and LVMi determined by magnetic resonance imaging in humans. METHODS: Sixty-two normal subjects were studied. Signal-averaged ECGs from the 12 standard leads were analysed in the standard frequency range (0.05-150 Hz), in the middle (25-100 Hz) and high end (50-150 Hz) of the standard frequency range and in the 150-250 Hz range. Root-mean square (RMS) values from the HF-QRS and QRS amplitude measurements from the standard ECGs were compared with LVM and LVMi. RESULTS: The correlations between LVMi and HF-QRS were similar to those between LVMi and standard ECG. When regarding LVM, however, the correlations found in the standard ECG were higher than those found in HF-QRS. CONCLUSIONS: Contrary to previous results in animals, we found in humans no better correlation between HF-QRS and LVM/LVMi than between standard ECG and LVM/LVMi.

Adult↗
PubMed2006

Serial changes in the high-frequency ECG during the first year following acute myocardial infarction.

BACKGROUND: Previous studies have shown reduced high-frequency QRS components (HF-QRS) after acute myocardial infarction (MI). The purpose of this study was to investigate serial changes in HF-QRS during the first year following acute MI. METHODS: A total of 75 patients were included. Standard- and high-frequency ECGs were recorded on five occasions during the year following the MI (a few days after the MI, after 6 weeks, and after 3, 6 and 12 months). RESULTS: There was a statistically significant increase in HF-QRS during the follow-up year (P = 0.002). There were no significant differences in HF-QRS when comparing either the infarct location or the presence or absence of reperfusive therapy. Large differences in HF-QRS were observed, both intra-individually and inter-individually, during the year. CONCLUSIONS: There was a statistically significant increase in HF-QRS during the year following acute MI.

Aged↗
PubMed2005

Problem-based learning of research skills.

PURPOSE: To determine whether a short-term, problem-based educational intervention leads to increased research activity among health care practitioners. SUBJECTS AND METHODS: Participant's success was evaluated as a composite of 2 outcomes. These were (1) reporting results for the project designed during the practicum and (2) conducting subsequent research activities. The study population included 36 clinical research outcomes projects developed by clinical practitioners, postgraduate trainees, and medical students during 6 separate practicums. All project teams received the same educational intervention, an "outcomes research practicum" that was divided into 4 primary learning modules administered over a 1 to 4 month period. Each module included a preparatory videotape lecture, supplemental readings, and a 90-minute interactive laboratory session during which faculty members worked with participants to develop answers to a series of predefined questions relating to the design of clinical outcomes research projects. Follow-up continued for a minimum of 12 months and a maximum of 36 months. RESULTS: Eighty-three percent of project teams completed all 4 practicum modules, and 69% completed one of the study outcomes (50% completed their research project and 47% completing a subsequent research activity). Practitioners were more likely to complete subsequent research activities, whereas trainees were more likely to complete their study project. DISCUSSION: This short-term, problem-based educational intervention was successful in increasing the collective research activities of participants. Further, more rigorous structured research is needed to determine the ultimate impact on practice change and patient outcomes.

Education, Medical, Continuing↗
PubMed2005

Development of an automated Selvester Scoring System for estimating the size of myocardial infarction from the electrocardiogram.

Although the Selvester Scoring System for estimating the size of myocardial infarction from the standard 12-lead electrocardiogram (ECG) has potential clinical value, it has found limited application because of the difficulties in making precise and reproducible measurements. The objective of this study was to develop software to automate the Selvester Scoring System, thus allowing wider application of the technique. The study was carried out using a training set consisting of ECG data recorded from 705 individuals with and without previous myocardial infarction. Algorithms for the 50 criteria in the Selvester Scoring System were iteratively improved by comparison of scores obtained by 2 experienced cardiologist investigators with those generated by the program. The final version was evaluated in a test set consisting of 60 ECGs by comparing scores derived by cardiologist investigator with those obtained by the program. The disagreements occurred only in 1.1% of the score comparisons and in 1.6% of the specific measurements. In all cases in which a disagreement occurred, it resulted from very small differences in measurements. These results indicate that the algorithm for automated application of the Selvester Scoring System is adequate for both clinical and research applications.

Algorithms↗