Electrocardiography of the left ventricle in coronary artery disease and hypertrophy
This thesis describes a series of studies which were undertaken to improve the diagnostic accuracy of the electrocardiogram (ECG), given the availability of computer assisted measurement techniques. Scalar 12 lead electrocardiograms have been recorded from over 200 cardiac patients recruited specifically for this study. Over 1,500 additional ECGs were available from normal and abnormal test populations. The ECG measurements were correlated with clinical, echocardiographic, radionuclide, coronary angiographic and contrast angiographic data of the left ventricle in order to meet the aims of the study. The history of electrocardiography was reviewed both with respect to the technique itself and the evolution of equipment through to present day computer assisted technology for recording and measurement of ECG waveforms. In addition, the development of echocardiography, nuclear cardiology and cardiac catheterization was also reviewed with particular attention being given to recent developments in technology which have allowed a reappraisal of gold standards against which the ECG can be compared. With more specific relevance to the aim of this study, the development of ECG criteria mainly with respect to post mortem examinations was reviewed so that a contrast could be drawn with present day techniques. In particular, emphasis was laid on the twin areas of left ventricular hypertrophy and ischemic heart disease. Evaluation of left ventricular function from the scalar electrocardiogram was undertaken in two ways. First of all the latest ECG scoring system of Selvester was assessed, from which left ventricular ejection fraction could be calculated. Secondly, indirect evidence of left atrial overload from the electrocardiogram was also studied. It was shown that left ventricular function could be predicted qualitatively with reasonable accuracy in the early post infarct period (third day) using the 54 criteria/32 points scoring system.