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) recordings (standard + V_3-5R + V_7-9) during coronary angioplasty, we selected 68 patients with left circumflex balloon occlusions (posterior ischemia model) or proximal right coronary artery balloon occlusions (right ventricular [RV] ischemia model). ST-segment amplitudes (J + 60 ms) at preangioplasty baseline were subtracted from maximal ST amplitudes during balloon inflation to create a positive or negative change score (ΔST) for each of the 18 leads. ΔST elevation was used to describe a change in the ST level in the positive direction from baseline, whether or not actual ST elevation from the isoelectric line was present. ΔST depression was used to describe a change in the ST level in the negative direction from baseline, whether or not actual ST depression from the isoelectric line was present. ST amplitudes from 8 of the 12 standard leads were then used to estimate ST amplitudes at 192 body surface sites spanning the entire anterior and posterior thorax using the transformation technique of Lux. Thoracic distributions of the ΔST values were displayed on a torso figure, including locations of the 18 lead locations and points of maximal ST elevation and depression. The 192 estimated body surface unipolar leads were compared with 18-lead ECGs (bipolar and unipolar). During 53 left circumflex occlusions, the maximal ΔST elevation was always located in the 18-lead ECG, with the most frequent locations at leads III, II (41%), V_7-8 (34%), and V_5-6 (25%). The maximal ΔST depression was located outside the 18-lead ECG (89%), with the most frequent locations above standard lead V₂ (67%) and V₃ (14%). During 16 proximal right coronary artery occlusions, the maximal ΔST elevation was always located in the 18-lead ECG, with the most frequent locations at leads III (81%) and V_2-3R (13%). The maximal ΔST depression was located outside the 18-lead ECG (93%), with the most frequent locations above standard lead V₂ (50%), V₃ (14%), and V₄ (14%). We conclude that maximal ΔST elevation is always located in the 18-lead ECG and maximal ΔST depression is frequently located outside of 18-lead ECG during left circumflex and proximal right coronary artery occlusions. Future studies are required to determine the bipolar leads for the 192 estimated body surface potential mapping leads.