Assessment of myocardial ischemia by 12-lead electrocardiography and Frank vector system during coronary angioplasty: Value of a new orthogonal lead system for quantitative ST segment monitoring

Abstract

The optimal number and placement of electrocardiographic (ECG) leads to detect myocardial ischemia induced by coronary balloon inflation was assessed by analyzing ST segment changes in the standard 12-lead ECG and Frank X, Y, Z leads at 90-s intervals during 34 consecutive coronary angioplasty procedures. Mean occlusion time during angioplasty was 218 +/- 65 s. Myocardial ischemia, defined as transient angina or ST segment deviation greater than or equal to 1 mm in at least one lead, occurred in 33 (97%) of the 34 procedures. The most sensitive single leads (V2 or V3) detected 17 (51%) of 33 ischemic episodes. The best dual-lead combinations (leads V2 and V5, leads a VF and V3 and leads V3 and Y) increased the sensitivity of 69% (23 of 33). The three-lead combination V2, V5, Y had the highest detecting power (78% [26 of 33]). The X, Y, Z leads by themselves had a sensitivity of only 60% (20 of 33). From this proposed orthogonal lead system (V2, V5, Y), which combines anteroposterior (V2), left to right (V5) and inferosuperior (Y) forces, the spatial ST vector magnitude was calculated and monitored during balloon inflations. A good correlation was observed between this ST vector magnitude and the sum of ST deviations on the standard ECG (r = 0.940, p less than 0.00001), and these data were reproducible over sequential balloon inflations. The results of the study suggest that this orthogonal lead system is of considerable value in the detection and quantification of acute myocardial ischemia and, in this respect, is more useful than the Frank orthogonal vector system.

The relationship between electrical axis by 12-lead electrocardiogram and anatomical axis of the heart by cardiac magnetic resonance in healthy subjects

“…A similar method for determination of the electrical axis in the transverse plane was used, assuming that the chest leads in the transverse plane are separated by approximately 30°. It is accepted that leads V 2 and V 5 are approximately orthogonal (23). Lead V1 was considered to be 30° to the right of V2, leads V3 and V4 equally spaced between V2 and V5, and V6 30° posterior to V5 (Fig 2B).…”

Detection of Myocardial Ischemia With a Computer-Assisted 12-lead 24-hour ECG Monitoring System (EAGLE) in Patients With Suspected Unstable Angina

“…The ECG waveform is a real-time waveform, and artifact cannot be avoided. The 24-h recording of 3 Frank leads and the mathematical reconstruction of the standard 12-lead ECG from the Frank leads has been reported recently; 29,30 however, the clinical significance of this has not been validated yet.…”