NONINVASIVE CHARACTERIZATION OF THE SOUND PATTERN CAUSED BY CORONARY-ARTERY STENOSIS USING FTF FAEST ZERO TRACKING FILTERS - NORMAL ABNORMAL STUDY

In this article, a new approach has been proposed to investigate the e xtraction of useful information from diastolic heart sounds caused by partially occluded coronary arteries. This method, which estimates and tracks the zeros (poles) of the diastolic heart sounds directly, take s advantage of the FTF/FAEST (Fast Transversal Filters/Fast a Posterio ri Error Sequential) technique which possesses the fast convergence pr operty of the Recursive Least Square (RLS) method and the computationa l simplicity of the Least Mean Square (LMS) method. In previous studie s, the main assumption was that the diastolic heart sounds were a stat ionary process. Since the production of the heart sounds is not a stat ionary process, a new approach that performs well not only for station ary but also for nonstationary processes can be required. This require ment can be satisfied by the adaptive FTF/FAEST zero tracking method w hich provides fast and stable convergence as well as computational eff iciency since the adaptive FTF/FAEST zero tracking method is based on the exact minimization of least squares criteria and the filter weight s of this method are optimal at each time instant. The zero trajectori es of the diastolic heart sounds were used to diagnose patients as dis eased or normal. Results showed that the normal and abnormal records w ere incorrectly distinguished in only 6 of 35 cases using a blind prot ocol where analysis was done without knowledge of the actual disease s tates of the patients. The most discriminant time region of the zero t rajectories of the diastolic heart sounds associated with coronary art ery disease was between 200 and 300 msec after the second heart sound during the diastolic period.