טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentVitenberg Lilia
SubjectThe Early Detection of Myocardial Ischemia
DepartmentDepartment of Biomedical Engineering
Supervisor Professor Amir Landesberg


Abstract

Early diagnosis of myocardial ischemia has important therapeutic and prognostic implications. Ischemia leads to inhomogeneity the cardiac mechanical and electrical activity. The study aims to detect the earliest signs of ischemia and test the hypothesis that the statistical behavior of the ECG and the temporal changes in cardiac mechanics allow earlier diagnosis. In situ swine model of acute infarction was used (39.5 ± 8.4 kg, n=5). General anesthesia was maintained with Fentanyl and Pancuronium. Pressure transducers were inserted into the left ventricle and the aorta. Flow meter was placed around the ascending aorta. Left ventricle volume was accessed by sono-crystals. ECG was measured by the surface electrodes. Acute ischemia was produced by ligation of a large diagonal or marginal coronary artery. An algorithm for analyzing the beat to beat temporal ECG morphological changes and the trends in the mechanical performance was developed. The ECG variability was compared with the anticipated variability produced by the jitter. Consistent changes were obtained in only four parameters: maximal rate of pressure development, maximal rate of relaxation, ST elevation and ECG variability. The greatest ECG variability was observed in the QRS offset region. The earliest signs of ischemia appeared 50 to 400 seconds after the occlusion, and at the systolic phase: at the QRS offset variability and the maximal rate of isovolumic pressure development. The changes in the relaxation rate and the ST elevation appeared latter. Analysis of the cardiac mechanics and the changes in ECG morphology allows the early detection of the myocardial ischemia.