Thoracic location of the lead with maximal ST-segment deviation during posterior and right ventricular ischemia: Comparison of 18-lead ECG with 192 estimated body surface leads

By using our database of continuous 18-lead electrocardiographic (ECG) reco rdings (standard + V3-5R + V7-9) during coronary angioplasty, we selected 6 8 patients with left circumflex balloon occlusions (posterior ischemia mode l) or proximal right coronary artery balloon occlusions (right ventricular [RV] ischemia model). ST-segment amplitudes (J + 60 ms) at preangioplasty b aseline were subtracted from maximal ST amplitudes during balloon inflation to create a positive or negative change score (Delta ST) for each of the 1 8 leads. Delta ST elevation was used to describe a change in the ST level i n the positive direction from baseline, whether or not actual ST elevation from the isoelectric line was present. Delta ST depression was used to desc ribe a change in the ST level in the negative direction from baseline, whet her or not actual ST depression from the isoelectric line was present. ST a mplitudes from 8 of the 12 standard leads were then used to estimate ST amp litudes at 192 body surface sites spanning the entire anterior and posterio r thorax using the transformation technique of Lux. Thoracic distributions of the Delta ST values were displayed on a torso figure, including location s of the 18 lead locations and points of maximal ST elevation and depressio n. The 192 estimated body surface unipolar leads were compared with 18-lead ECGs (bipolar and unipolar). During 53 left circumflex occlusions, the max imal Delta ST elevation was always located in the 18-lead EGG, with the mos t frequent locations at leads III, II (41%), V7-8 (34%), and V5-6 (25%). Th e maximal Delta ST depression was located outside the 18-lead ECG (89%), wi th the most frequent locations above standard lead V-2 (67%) and V-3 (14%). During 16 proximal right coronary artery occlusions. the maximal Delta ST elevation was always located in the 18-lead EGG, with the most frequent loc ations at leads III (81%) and V2-3R (13%). The maximal Delta ST depression was located outside the 18-lead ECG (93%), with the most frequent locations above standard lead V-2 (50%), V-3 (14%), and V-4 (14%). We conclude that maximal Delta ST elevation is always located in the 18-lead ECG and maximal Delta ST depression is frequently located outside of 18-lead ECG during le ft circumflex and proximal right coronary artery occlusions. Future studies are required to determine the bipolar leads for the 192 estimated body sur face potential mapping leads.