Evaluation of Electrophysiological Alteration Created by Local Autonomic Dysfunction Using Magnetocardiography

Abstract

The pattern of local neurocircuitry is likely to play a critical role in influencing electric heterogeneity of repolarization (EHR), a fundamental factor in arrhythmogenesis. Magnetocardiography (MCG) has revolutionized the investigation of cardiac cellular physiology and advanced our understanding of basic mechanisms of electrical activity. In our study we investigated whether MCG mapping could expose the electrophysiological alteration created by local autonomic dysfunction and which are sensitive to myocardial cooling. 24-h Holter monitoring, ECG, Tissue Doppler echocardiograms (TDE) and MCG  records were performed in  4 male  patients affected by  ventricular extrasystolia Patients were without cardiac structural abnormalities, history of myocardial infarction and sign of ischemia on resting ECG. Current density vector (CDV) maps were plotted in the course of ventricle repolarization interval by the magnetic moments method of the “inverse problem solution”. The measurements were made before (baseline) and shortly (15 minutes) after 4 patients ingested 150 ml of cold (6 degree C) water.  Standard ECG patterns and TDE were unaffected when the patients drank cold water. CDV directions differed significantly between 2 measurements. MCG examinations before ingestion showed additional   local area with high level of regional EHR. The changes in the CDV maps indicated decreasing of the heterogeneity of the repolarization by cooling the surface of the apex of the ventricle which was located closer to the stomach. Our findings can be understood in terms of the known temperature sensitivities of the kinetics of the membrane ion channels responsible for recovery and suggest a potential role of MCG in the evaluation of electrophysiological alteration created by local autonomic dysfunction.