A Magnetic Determination of the Relationship Between the S-T Segment Shift and the Injury Current Produced by Coronary Occlusion,

摘要

The relationship between the S-T segment shift and the injury current from seven dogs undergoing coronary artery occlusion was studied,using the direct-current magnetocardiogram (dcMCG). The purpose was to clarify,with this new technique,the origin of the S-T segment shift in acute ischemia and infarction. Previous measurements,consisting of dc electrograms recorded from the surface of the exposed heart,left some doubt because of the disturbance of the volume conductor;the dcMCG allows the deep currents to be measured around the intact torso without this disturbance. The occlusions took place in the M.I.T. shielded room,where a sensitive magnetometer recorded the dcMCG's at various locations around the torso. These dcMCG's were recorded at various times before and during a sequence of short trial occlusions and the final occlusion. Within 20seconds after occlusion there appeared S-T segment and baseline (dc) shifts on the dcMCG's which were equal and opposite;this opposition was maintained for at least 15minutes,after which both shifts slowly decreased. A linear regression analysis showed that there was a strong correlation between the S-T and baseline shifts,at a high confidence level.