SIMULTANEOUS ST-SEGMENT MEASUREMENTS USING STANDARD AND MONITORING-COMPATIBLE TORSO LIMB LEAD PLACEMENTS AT REST AND DURING CORONARY-OCCLUSION

Electrocardiographic recordings used to assess ST-segment deviation ar e performed using both standard and torso limb lead positions, where b ony prominences give more artifact-free signal. Whereas significant QR S artifact can be introduced by such changes in lead location, the imp act on ST-segment measurements has never been assessed. Digital electr ocardiographic recordings were performed in 29 patients throughout ele ctive angioplasty balloon inflation in the left anterior descending (n = 12), right coronary (n = 14), and circumflex (n = 3) arteries. In a ll cases, unipolar leads V-1, V-4, and V-6 were affixed to the torso l ead positions, allowing reconstruction of simultaneously acquired stan dard and modified 9-lead electrocardiograms (ECGs). ST levels in the 2 6 patients who had ST deviation during angioplasty were compared at bo th baseline and peak ischemia of up to 1,046 mu V in the anterior, and 551 mu V in the inferior leads. Differences in recorded ST levels for modified versus standard lead locations were all <100 mu V, even at p eak ischemia. Although ST-segment elevation in the inferior leads appe ared to show slightly more pronounced differences between lead sets th an did anterior elevation, all differences were <100 mu V. Thus, measu rement of ST-segment levels appears unlikely to be importantly affecte d by the intermixture of ECGs recorded with standard lead positions an d ECGs recorded with monitoring-compatible lead positions on the torso . Recalibration of ST-segment measurements may he necessary for meticu lous quantification of ischemia, infarct size, or other measurements t hat might be affected by variations <100 mu V.