A prototype expert system for analysis and diagnosis of single chamber paced ECGs

A rule-based expert system has been proposed that will assist clinicians in the often difficult task of analyzing multi-channel pacemaker electrocardiograms (ECGs). Analysis of the pacemaker ECGs is important to the follow-up evaluation of patients with implanted pacemakers. Because of the complexity and variability of pacemaker algorithms, diagnosis of pacemaker ECGs is often considerably more difficult than the interpretation of usual ECGs. However, comparatively little work has been done in this area, mainly since the diversity and complexity of pacemaker logic makes interpretation a difficult task. The proposed prototype expert system on interpretation of the pacemaker ECG can provide great clinical benefit because few clinicians are adequately trained in the diagnosis of such ECGs for the interpretation of pacemaker functionality. The expert system guides the clinicians through the analysis of the pacemaker ECGs during a follow-up. The program bases its conclusion on information it receives from the user's response to questions the system poses regarding specific characteristic of the ECG waveform during multiple cycles. The clinician simply answers the question with Yes or No. The system uses a top-down method to analyze the ECG information. The system evaluates two domain specific tasks during the interaction with the user. First, the system starts with analyzing the pacemaker ECGs for pacemaker malfunctions (no output, intermittent output, noncapture, intermittent capture, oversensing or undersensing). When the malfunction type is identified, the system starts the second task: diagnosis of the pacemaker ECGs. During this task the expert system tries to determine the cause of the pacemaker malfunction (e.g., leadelectrode fracture, pacemaker configuration setting, pacemaker malfunction etc.). The expert system gives a solution for the pacemaker malfunction when the cause of malfunction is found. Evaluation of this system by medical experts demonstrates that it mimics an instructional assistant in a consistent and reliable manner. Although the system has not been tested extensively, preliminarily tests show that the prototype could identify all the presented test cases. The expert system described in this report is still a prototype. The prototype contains the domain specific knowledge of the single chamber pacemaker. The domain specific knowledge of dual chamber pacemakers is not yet implemented in the system. Thus, further development on the expert system is necessary.