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Computer studies in electrocardiography
Başlık:
Computer studies in electrocardiography
Yazar:
Macfarlane, Peter W., author.
ISBN:
9780438058279
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (463 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: T. D.V Lawrie.
Özet:
An investigation into the theory and practice of electrocardiography has been described. The methods developed were applied to the analysis and interpretation by computer of 3 orthogonal lead and conventional 12 lead electrocardiograms (ECGs) from 1100 patients. The history of the development of electrocardiography was reviewed and the clinical application of this diagnostic aid briefly discussed. To assist the theoretical considerations, the concept of an equivalent cardiac generator was utilised. Several examples, including the single dipole, multipolar expansion of a potential function and a set of multiple dipoles were considered in detail in a review of established theoretical and clinical studies. The conclusion reached was that the single dipole is clinically the most suitable and at the same time a theoretically satisfactory equivalent cardiac generator. A new equivalent cardiac generator, consisting of a network of resistors and batteries was designed for the purpose of extending previously existing EGG lead field theory. Network analysis led to the formulation of an equation relating the potential measured by any ECG lead to the lead field strength and the single resultant electrical dipole moment of the cardiac electromotive forces. The theory of lead field measurement from torso model studies was reviewed and corrected, since previously published data from such work were subsequently used in the design of a modified axial orthogonal lead ECG recording system. This formed part of the EGG data acquisition system which consisted of two multichannel magnetic tape recorders, various EGG amplifiers, display facilities and a small PDP-8 digital computer. The 1100 patients in this study were each classified clinically on the basis of cardiovascular, radiological and electrocardiographic findings. In many instances haemodynamic and angiocardiographic data were also available. Serum enzyme changes were also taken into account in the diagnosis of myocardial infarction. No post mortem data was used. Each patient had a 3 lead and 12 lead ECG tape recorded in groups of 3 leads simultaneously. These analogue signals were replayed to a PDP-8 computer for conversion to digital form and storage on digital magnetic tape. This data was subsequently transferred to KDF9 computer compatible magnetic tape. This method of recording allowed the same ALGOL wave recognition program to be used on a KDF9 computer for wave recognition of EGGs from both lead systems. The program incorporated a new set of data smoothing equations to remove 50 Hz interference and minimise somatic tremor. No detailed attempt to analyse cardiac arrhythmias was included. All wave amplitudes and durations were measured; for the 3 lead EGG vector magnitudes and orientations were also calculated. A further KDF9 ALGOL program interpreted the 12 lead EGG measurements on the basis of existing criteria. These interpretations were compared with those of a panel of cardiologists to assess the accuracy of the computing method and to classify each 12 lead ECG. The corresponding 3 lead ECGs in each classification were used in the computer assisted derivation of means, standard deviations and 96% ranges of all orthogonal lead parameters from each normal or abnormal group. From these statistics, a new set of diagnostic criteria was formulated for the 3 lead ECG derived from the modified axial lead system. These were used in the computer interpretation of all 3 lead ECGs by a KDF9 ALGOL program. The 3 and 12 lead ECG interpretations were compared and discrepancies discussed in terms of false positive, false negative and, where appropriate, clinical findings. The main finding was that the 3 orthogonal lead system was clinically as useful as the conventional 12 lead system. This is particularly favourable for computer assisted interpretation since the data storage requirement for the 3 lead ECG is reduced by a factor of 4 and the time for analysis reduced by a factor of 3 compared to that for the 12 lead ECG. It was thus concluded that the use of three orthogonal lead electrocardiography is the method of choice for computer assisted interpretation of electrocardiograms.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684658.1) | 684658-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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