Stanford Goldman...[et al.]. / "Nov. 15, 1950." / Bibliography: p. 11. / Army Signal Corps Contract No. W36-039-sc-32037. Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on December 1, 2009. Major professor: Dr. Lily Laiho. "Presented to the faculty of California Polytechnic State University, San Luis Obispo, California." "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Engineering." "June 2009." Includes bibliographical references (p. 29-30).

Includes bibliographical references (p. 64-65).

published_or_final_version / Community Medicine / Master / Master of Philosophy

The accurate differentiation of a ventricular from a supraventricular origin of a wide QRS tachycardia (QRS > 120 milliseconds) is an important clinical problem. Misdiagnosis of this arrhythmia can lead to institution of inappropriate drug therapy acutely with potentially catastrophic consequences. Various diagnostic aids have been used to obtain electrocardiographic potentials to aid in the differentiation. This report assesses the clinical usefulness of oesophageal electrocardiography in the differentiation of wide complex tachycardias and describes a simple, safe technique to obtain oesophageal electrocardiograms. Eighteen consecutive patients between the ages of 27 and 71 years who were haemodynamically stable were selected for this study. The technique was performed in the following manner: A temporary pacing catheter was lubricated and passed nasally and advanced with the patient being instructed to swallow. Adjustments in catheter depth were made as necessary to obtain an optimal recording on a standard electrocardiograph recorder. Satisfactory placement with minimal patient discomfort was achieved within 6.5 minutes (average 4.5 minutes) in all cases. High quality tracings were obtained in every instance. In the 18 patients with tachyarrhythmia, AV dissociation consistent with ventricular tachycardia was demonstrated in 11 instances; in the remainder the diagnosis was supraventricular tachycardia. Of the 11 patients diagnosed as ventricular tachycardia, 9 were initially misdiagnosed as supraventricular tachycardia, whilst only 1 of 7 patients with supraventricular tachycardia was misdiagnosed. This study has demonstrated that oesophageal electrocardiography is useful in the differentiation of wide complex tachycardias. The technique outlined in this report is simple and offers the following advantages: the temporary pacing catheter is associated with minimal discomfort; the catheter allows easy manoeuverability within the oesophagus which allows proper depth to be easily obtained; the equipment used is routinely available. Therefore the technique offers a rapid, safe and simple method of obtaining an oesophageal electrocardiogram which is invaluable in the electrocardiographic differentiation of a wide complex tachycardia. / Thesis (M.Med.)-University of Natal, Durban, 1990.

No description available.

Background: The 12-lead electrocardiogram (ECG) is a pivotal clinical investigation for evaluations of disorders of myocardial electrophysiology and function. Myocardial ischemia is generally diagnosed on the basis of clinical history, combined with ST segment shifts and T wave changes on resting 12-lead ECG. The ECG is also used as a monitoring tool for assessment of resolution of transmural ischemia following emergency treatment. Because this technology is easy, noninvasive, and inexpensive, it represents a convenient central investigative modality. On the other hand, the 12-lead ECG exhibits very low predictive accuracy for the diagnosis of ischemia in the absence of concurrent symptoms. Even if ECG monitoring is combined with treadmill exercise, the sensitivity and positive predictive accuracy for detection of myocardial ischemia are only around 50% - 75%. Therefore, information from the ECG, combined with exercise test, does not usually have a large influence on clinical decision-making. A number of imaging techniques may be combined with pacing-induced tachycardia or pharmacological stress in order to improve the diagnostic accuracy of such provocative tests for ischemia beyond the level provided by continuous ECG monitoring alone. These include echocardiography, nuclear imaging with single photon emission computed tomography (SPECT) or positron emission tomography (PET) and magnetic resonance imaging. All add to the diagnostic accuracy of the provocative tests performed, but involve considerably incremental costs. The question therefore arises: is it possible to refine continuous ECG analysis during provocative testing in such a way that the diagnostic accuracy of the procedure can be improved? The majority of clinical studies has examined the accuracy or otherwise of the diagnosis of myocardial ischemia utilizing fluctuation of the ST segments during either “spontaneous” ischemia or during provocative manoeuvres (e.g. exercise). As previously stated, the diagnostic accuracy of such analyses tends to be mediocre; when subjected to utility evaluation under Bayesian considerations, they often add little to history/physical examination. However, a number of potential refinements of 12-lead ECG analysis have been proposed, in order to improve both detection and as well as localization and quantitation of ischemia. These include evaluation of a variety of the component waveforms of both the QRS complex and the ST segment of the ECG. Current experiments The currently described series of investigations arose from preliminary findings that myocardial ischemia in a canine model was associated with transient fluctuations in QRS entropy. Both evaluations performed related to the hypothesis that reversible myocardial ischemia causes transient increases in entropy within QRS complexes and ST segments of the human 12-lead ECG. A series of preliminary experiments suggested that such changes did indeed occur, mainly within the ST segment. The first series of experiments performed compared conventional continuous ST segment analysis within the 12-lead ECG is vs. continuous evaluation of entropy-derived parameters for the localization of ischemia induced by balloon inflation during non-emergency coronary angioplasty. In a series of 103 patients, localization of ischemia was similarly accurate for the entropy-based method and the ST segment assessment method. Ischemic zones were correctly localized by these approaches in 88% and 80% of cases, respectively (p not significant). There was poor concordance between the extent of ST elevation and changes in ST segment entropy. In a small subset of patients with complete bundle branch block and/or ST depression on resting ECG (n=22), entropy-based localization of ischemia was possible in 55% of cases compared with 41% via ST segment assessment (difference not significant). Post hoc analysis revealed that entropy fluctuations arose throughout the ST segment rather than predominantly at the J-point. The second series of experiments was carried out on patients undergoing pacing-induced provocation of possible myocardial ischemia, with scanning via myocardial perfusion imaging (SPECT) examination. As with the first series, 12-lead ECG recording and ST trend monitoring were performed during the pacing procedure. The ST segment deviation and the entropy-based analyses were used for localization of possible ischemia. Data analyses were correlated with myocardial perfusion imaging results. A total 43 patients were studied. Categorization of ischemia via ST segment assessment had only 30% concordance with myocardial perfusion imaging results, while entropy-based analyses had 58% concordance. Therefore neither “conventional” (i.e. ECG-based ST segment analysis) nor novel entropy-based analyses are currently of clinical utility for detection of tachycardia-induced ischemia. / Thesis (M.Med.Sc.) - University of Adelaide, School of Medicine, 2008

Antenatal fetal surveillance is a field of increasing importance in modern obstetrics. Measurements extracted (such as fetal heart rate) from antenatal fetal monitoring techniques have the potential to reduce the social, personal and financial burdens of fetal death on families, health care systems and the community. Techniques to monitor the fetus through pregnancy have been developed with the aim of providing information to enable the clinician to diagnose fetal wellbeing, characterise development and detect abnormality. An early diagnosis before delivery may increase the effectiveness of the appropriate treatment. Over the years, various research efforts have been carried out in the field of fetal electrocardiography by attaching surface electrodes to the maternal body. Unfortunately the desired fetal heartbeat signals at the electrode output are buried in an additive mixture of undesired interference disturbances. In this thesis, a non-invasive fetal electrocardiogram machine has been designed, constructed and implemented. This machine is composed of three modified electrocardiogram circuits and an external soundcard. Data was acquired from four surface electrodes placed on the maternal body. Eleven pregnant subjects, with a gestation age between the 30th and 40th weeks of pregnancy, were used to investigate the validity of this machine. Fetal R-waves were detected in 72.7 percent of subjects. The development of a non-invasive machine, capable of detecting and recording valuable anatomic and electrophysiological information of a fetus, represents an important tool in clinical and investigative obstetrics.

Diss. (sammanfattning) Umeå : Univ., 2005. / Härtill 4 uppsatser.

Thesis (M.Sc. (Biomedical Instrumentation))--Mahidol University, 1984.