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Biomedical subjects

R A Warner

Publications and source records attributed to R A Warner.

At least 19 recordsLinked to original sources
PubMed2001

Standards for the function of an academic 12-lead electrocardiographic core laboratory.

An academic 12-lead electrocardiogram (ECG) core laboratory aims to provide the highest possible quality ECG recording, measurement, and storage to aid clinicians in research into important cardiovascular outcomes and to maximize the credibility of scientific results based solely, or in part, on ECG data. This position paper presents a guide for the structure and function of an academic ECG core laboratory. The key functional aspects are: 1) Data collection, 2) Staff composition, 3) Diagnostic measurement and definition standards, 4) Data management, 5) Academic considerations, 6) Economic consideration, and 7) Accreditation. An ECG Core Laboratory has the responsibility for rapid and accurate analysis and responsible management of the electrocardiographic data in multicenter clinical trials. Academic Laboratories, in addition, provide leadership in research protocol generation and production of research manuscripts for submission to the appropriate peer-review journals.

Accreditation↗
PubMed2001

Validation of advanced ECG diagnostic software for the detection of prior myocardial infarction by using nuclear cardiac imaging.

The investigators report the diagnostic performance of the latest version (Version 2.5) of the recently developed Cardiovise algorithm for detecting prior myocardial infarction (MI). The Cardiovise 2.5 prior MI algorithm, a component of Cardiovise Cardiac Diagnostic System (Inovise Medical, Inc, Newberg, OR), uses scalar QRS, scalar T wave, and vectorcardiographic QRS criteria for detecting, sizing, and localizing prior MI. In this study only the detection part of the algorithm's performance was evaluated, using 105 patients with and 98 patients without prior MI as indicated by the results of cardiac imaging with Sestamibi. The specificity, and sensitivity of Cardiovise 2.5 for detecting prior MI in this population of patients are 97% and 79%, respectively. The sensitivity and overall diagnostic performance of Cardiovise 2.5 was significantly better than those of a total of 6 human readers (3 cardiologists and 3 primary care physicians) and to 2 commercially available ECG diagnostic algorithms.

Algorithms↗
PubMed2001

A dynamic three-dimensional display of ventricular excitation and the generation of the vector and electrocardiogram.

Computer models, such as those produced by Solomon and Selvester, have helped increase our understanding of the heart's electrical activity. In the present report, we describe a dynamic three-dimensional computerized display of the myocardial excitation sequence that is based on this fundamental research. The display is based on the vectors of the potential differences generated in the various parts of the myocardium during its excitation. The sums of these individual vectors form composite vectors that are related to the ECG signals recorded from the body's surface. The display simultaneously portrays the temporal changes of the composite vectors in 3 dimensions and in each plane (the transverse, frontal and left sagittal). It also shows the corresponding changes in the QRS complexes in each of the 12 scalar ECG leads. The display shows the patterns of activation of the normal heart and an example of posterolateral myocardial infarction. The technique facilitates the understanding of myocardial activation and how it is modified by specific pathological conditions. It is believed that this method of presentation and visualization of the generation of the ECG will be of value in the teaching of this process.

Computer Simulation↗
PubMed2000

Comparison of an automated thrombolytic predictive instrument to both diagnostic software and an expert cardiologist for diagnosis of an ST elevation acute myocardial infarction.

Because the electrocardiograms (ECGs) of patients with symptoms suggesting an acute thrombotic coronary occlusion are typically read by physicians relatively inexperienced in this skill, it is important to develop automated decision support. A Thrombolytic Predictive Instrument (TPI) is now available along with the standard diagnostic software in a commercially available electrocardiograph. This study evaluates the performance of the predictive software in comparison to both an expert cardiologist and standard diagnostic software. True sensitivity and specificity cannot be determined because acute coronary angiography was not performed. The specificities determined by this study were excellent (98% and 99%), and the sensitivities were very good (72% and 78%). These results that the TPI will be only rarely applied to patients who do not indeed have an acute coronary thrombosis. However, the reasons for even this small number of presumably falsely TPI positive patients should be determined and analyzed. It is unlikely that alterations of the thresholds for TPI activation will significantly improve on this very good level of sensitivity, without prohibitively decreasing specificity.

Clinical Competence↗
PubMed2000

The correlation between presenting ST-segment depression and the final size of acute myocardial infarcts in patients with acute coronary syndromes.

The use of reperfusion therapy in patients with ST elevation acute coronary syndromes had been established. However, reperfusion therapy is usually considered contra-indicated in those with ST depression, despite the knowledge that regional posterior infarction is typically indicated by ST depression maximal in leads V1 to V3 and nonregional subendocardial infarction is typically indicated by marked ST depression maximal in other leads. This study of patients with non-ST-elevation acute coronary syndromes investigates the quantitative relationship between presenting ST depression and final QRS changes in both of these subgroups. The final QRS score was significantly higher (2.44 points) than that of a control group with not ST depression, (1.55 points) in the group with maximal ST depression in V1 to V3 (P = 0.04). However, in the entire population, there was a highly significant correlation (P = .003) between the sum of the presenting ST depression and the final QRS score. Trials of reperfusion therapy will be required to determine if such evolution to electrocardiogram documented acute myocardial infarction can be prevented in patient with marked ST depression acute coronary syndromes.

Case-Control Studies↗
PubMed1999

Using digital versus analog ECG data in clinical trials.

In 54 patients, we measured 3 different electrocardiogram (ECG) parameters required in the Symphony 1 trial and compared various combinations of pairs of measurements from 4 different sets of analog data and 1 set of digital data. Particularly for measurements of the durations of R waves in lead aVF, we found poor intraobserver and interobserver reliability and poor agreement between analog and digital data. There was much better agreement in measurements of the amplitudes of S waves in lead V3. The poorer agreement involving durations appears to be due to difficulties in accurately identifying the offsets of portions of the QRS complex, especially in lead AVF. We conclude that, particularly in measurements of duration, digital and analog data are not equivalent.

Analog-Digital Conversion↗
PubMed1994

Using directly acquired digital ECG data to optimize the diagnostic criteria for anterior myocardial infarction.

The use of a newly developed method of directly transferring digital data from Marquette electrocardiogram (ECG) systems (Milwaukee, Wisconsin) to personal computers for subsequent storage and analysis is illustrated. This method can eliminate the slowness and inaccuracy associated with measuring relevant ECG parameters from analog tracings and manually entering the data into a computer. In this study, the new method was used to derive ECG criteria for anterior myocardial infarction and to compare their performances to those of the current Marquette 12SL diagnostic program and of a group of cardiologists who had also interpreted the ECGs. Using angiographic data, 82 normal subjects and 55 patients with anterior myocardial infarction were identified. The digital ECG data from the patients in each group were transferred to a personal computer and frequency distributions of these data were generated. From these frequency distributions, the ECG criteria that most reliably separated the two groups were identified. The diagnostic performance of the best of these empirically derived criteria appears clinically superior to the performances of both the 12SL program and the cardiologists who had also interpreted the ECGs.

Adult↗
PubMed1992

An analysis of symptoms in patients with permanent ventricular pacemakers.

The prevalence and severity of symptoms of the "pacemaker syndrome" were investigated in 64 patients with VVI pacemakers and compared, in the same patients, to a series of control symptoms, unrelated to pacemaker function. Symptoms were also compared in patient groups unlikely to have the "pacemaker syndrome" (atrial fibrillation), most likely to have such symptoms (retrograde atrial activation) and in an intermediate group (competitive paced and sinus rhythms). There was a linear relationship between the frequency and severity of "pacemaker" symptoms and control questions in all groups and no preponderance of "pacemaker" symptoms in any group. The study provides an estimate of the number and severity of symptoms in patients with VVI pacemakers, demonstrates the non-specificity of the "pacemaker syndrome" and shows no evidence of a sub-clinical "pacemaker syndrome" in the patients observed.

Aged↗
PubMed1991

Mitral valve prolapse and neuroticism in chest pain patients with normal and diseased coronary arteries.

Patients with chest pain and normal coronary arteries (NCA) score higher on measures of neuroticism than patients with coronary artery disease (CAD). This relationship, coupled with findings linking mitral valve prolapse (MVP) and anxiety disorders, led us to examine prospectively the possibility that a greater incidence of MVP among NCA patients accounts for their elevated neuroticism scores. One-hundred-forty-four patients completed psychological tests and a structured interview prior to cardiac catheterization. Forty-one of the 144 patients (28%) had normal coronary arteries. Within the NCA group 29 percent had MVP; within the CAD group only 13 percent had MVP. Despite the significant difference between NCA and CAD groups on measures of neuroticism, there were no differences as a function of MVP status, nor was there an interaction of MVP and coronary arterial status. These findings support the case for an association between NCA and neuroticism independent of the presence or absence of MVP.

Angina Pectoris↗
PubMed1990

Use of hepatic vein catheterization in the evaluation of patients with anasarca.

In patients with anasarca, the relative importance of cardiac, pulmonary and/or hepatic dysfunction is often difficult to determine. Conventional use of the Swan-Ganz catheter helps to separate the contributions of right and left heart disease, but it is seldom used to evaluate liver dysfunction. This report describes passage of a Swan-Ganz catheter into the hepatic vein prior to pulmonary artery placement in 11 patients. Hepatic vein catheterization permitted wedged hepatic venography using contrast media and measurement of the wedged and free hepatic venous pressures. All 11 patients had pulmonary hypertension; three had cor pulmonale only, and the others had combinations of left and right heart failure. In addition, six patients had either a cirrhotic pattern on venography, or portal hypertension. Only three of these six patients had previous clinical evidence of liver disease. This study does not prove that identification of hepatic dysfunction by this method improves the outcome in such patients. However, this low risk modification of standard pulmonary artery catheterization provides additional information which is clinically useful in searching for and avoiding complications of cirrhosis, as well as offering a clearer understanding of pathophysiology in acute multisystem disease.

Ascites↗
PubMed1988

One-year psychosocial follow-up of patients with chest pain and angiographically normal coronary arteries.

As many as 30% of patients with chest pain symptoms who are referred for arteriography are found to have normal coronary arteries. Research has shown that patients with anginal symptoms and normal coronary arteries score higher on neuroticism measurements (anxiety, depression and somatic concerns) at the time of catheterization than patients with anginal symptoms who have coronary artery disease. Research examining the cardiac course of chest pain patients with normal coronary arteries indicates that this is a nonprogressive disorder. Although follow-up studies of these patients report continued chest pain and diminished physical activity, these studies have ignored the psychologic status of the patients. Thus, it is not known whether their higher neuroticism scores at the time of catheterization persist following angiography or whether such elevated indexes of neuroticism are transient phenomena associated with precatheterization anticipatory stress. The present study examined 48 Veterans Administration Medical Center patients: 24 with anginal symptoms and normal coronary arteries and 24 with documented coronary artery disease. The patients completed a structured clinical interview and a set of psychologic inventories on the day before catheterization and 1 year later. The findings established continued high neuroticism scores among patients with anginal symptoms only and supported the findings of other investigators regarding continuing chest pain and restricted physical activity. The knowledge alone of benign coronary artery status resulted in virtually no change in the psychosocial status of these patients. Alternative treatment methods are discussed.

Angiography↗
PubMed1988

Relationship between Doppler left ventricular diastolic filling indexes and the electrocardiographic criteria for left atrial enlargement.

Traditional electrocardiographic (ECG) criteria for left atrial enlargement (LAE) emphasize the increased amplitude and width of the corresponding component of the hypertrophied atrium. Although a correlation exists between LAE and ECG criteria, a cause-and-effect relationship has not been conclusively demonstrated. Because the diastolic properties of the left ventricle directly influence left atrial emptying, these properties might also influence the ECG diagnosis of LAE. Therefore, the authors hypothesized that the ECG criteria for LAE are influenced by diastolic properties of the left ventricle as defined by Doppler-derived parameters.

Atrial Fibrillation↗
PubMed1988

Usefulness of abnormalities of repolarization in the electrocardiographic diagnosis of healed myocardial infarction.

The authors evaluated the ability of criteria involving abnormalities of repolarization to diagnose healed myocardial infarction (MI). They studied the Q, R, S, and T waves and the ST-segments of the electrocardiograms (ECGs) of 60 angiographic-normal patients, 63 patients with angiographic evidence of healed inferior MI, and 33 patients with angiographic evidence of anterior MI. The best individual criteria involving repolarization were T wave amplitude less than or equal to 0.4 mm in lead II for inferior MI (specificity, 93%: sensitivity, 67%) and T wave amplitude greater than 2.4 mm for anterior MI (specificity, 100%: sensitivity, 27%). These T wave criteria enhanced the diagnostic performances of otherwise marginal QRS criteria for both inferior and anterior MI. The authors conclude that ECG criteria that involve abnormalities of the T waves are useful for diagnosing healed MI.

Electrocardiography↗