Journal of electrocardiology
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Case Reports
Intraatrial conduction delay associated with an epicardial implantable cardioverter-defibrillator.
The implantable cardioverter-defibrillator (ICD) has become an important mode of therapy for patients at risk for sustained ventricular arrhythmias. While the survival benefit of these devices is clear, adverse consequences are coming to light. The authors report a case of dramatic intraatrial conduction delay associated with repeated ICD shocks, resulting in pacemaker syndrome in a patient who had received both an ICD and a dual-chamber pacemaker. This and other conduction disturbances may become more common as experience with ICDs grows, and may demand adjunctive or alternative therapies to prevent frequent shocks.
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The authors have investigated potential applications of artificial neural networks for electrocardiographic QRS detection and beat classification. For the task of QRS detection, the authors used an adaptive multilayer perceptron structure to model the nonlinear background noise so as to enhance the QRS complex. ⋯ For electrocardiographic QRS complex pattern classification, an artificial neural network adaptive multilayer perceptron was used as a pattern classifier to distinguish between normal and abnormal beat patterns, as well as to classify 12 different abnormal beat morphologies. Preliminary results using the MIT/BIH (Massachusetts Institute of Technology/Beth Israel Hospital, Cambridge, MA) arrhythmia database are encouraging.
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The objective of this study was to prospectively determine the utility, efficiency, and reliability of early prehospital 12-lead electrocardiogram (ECG) application, the improvement in prehospital diagnostic accuracy, and paramedic and base physician opinions regarding early application of prehospital 12-lead ECGs in a broad range of stable chest pain patients. The patient population consisted of cooperative, stable adult prehospital patients with a chief complaint of nontraumatic chest pain of presumed ischemic origin. From July 17, 1989 through January 1, 1990 paramedics acquired prehospital 12-lead ECGs on 680 stable adult chest pain patients. ⋯ Paramedic application of prehospital 12-lead ECGs was found to be efficient and reliable, and it can be applied to most cooperative stable adult prehospital chest pain patients. Prehospital 12-lead ECGs significantly improve base physicians' diagnostic accuracy in myocardial infarction, angina, and nonischemic chest pain patients. Paramedic and base physicians' opinions regarding early application of prehospital 12-lead ECGs during patient evaluation were favorable.
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A case is presented in which markedly low surface electrocardiographic (ECG) voltage and an infarction pattern are rapidly reversed with renal hemodialysis for pulmonary edema. A patient presenting with QRS voltages below 0.1 mV in all the limb and augmented limb leads and a waveform pattern suggestive of an anterior and inferior myocardial infarction experienced a dramatic increase in voltage and a reversal of the infarction pattern after dialysis. ⋯ This case illustrates one source of diagnostic error, and that dialysis may result in large, rapid changes in the ECG. Diagnostic errors may be avoided by obtaining serial ECGs in patients undergoing dialysis.
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Perioperative cardiac morbidity remains a significant problem in both cardiac and noncardiac surgical patients. The role of perioperative myocardial ischemia appears to be important and is under active investigation. In a series of studies in 200 high-risk patients undergoing noncardiac surgery or coronary artery bypass graft (CABG) surgery, we measured the pre-, intra-, and post-operative electrocardiographic (ECG) ischemic patterns using either continuous 2-lead ambulatory (Holter) monitoring or continuous 12-lead (modified treadmill) monitoring. ⋯ Most ECG ischemic episodes were supply-dependent, not demand-dependent. Comparing the pattern of intraoperative ischemia with the chronic ambulatory preoperative pattern, we found that, under conditions of strict hemodynamic control, intraoperative ischemia apparently recapitulated the preoperative pattern, and that the stresses of anesthesia and surgery contributed less than previously thought. The highest incidence of ischemia occurred postoperatively, ranging between 30% and 60%, in both cardiac and noncardiac surgical patients.(ABSTRACT TRUNCATED AT 250 WORDS)