Computed ST forces of Frank and bipolar exercise electrocardiograms.

Abstract 1.1. Simultaneous CB 5 bipolar and Frank X, Y, and Z orthogonal ECG leads were recorded during a standardized exercise test on 36 ambulatory individuals. From analysis of direct-writing the CB 5 bipolar lead at the moment of cessation of exercise, 11 were classified by visual interpretation with an abnormal ST response, and 28 with a normal ST response to maximally tolerated exercise. An objective computer method confirmed these subjective clinical differentiations. Classification of responses from X, Y, and Z orthogonal leads was not more reliable than that from the CB 5 bipolar lead. 2.2. Multivariate analysis of normal and abnormal ECG responses grouped together showed the highest correlation between spatial and bipolar ST forces at the ST 2 locus at rest and during most of the recovery and at ST 1 locus during strenuous exercise and immediate recovery. During the second and third minute of recovery, there was no correlation between spatial and bipolar ST 3 forces. 3.3. Most of the ST 2 information related to the bipolar lead was located in the X lead of the Frank lead electrocardiogram. A satisfactory correlation between observed bipolar ST 2 and predicted bipolar ST 2 forces (computed from X, Y, Z, frontal, and spatial measurements of the Frank lead ECG) was obtained by external checking in other patients. 4.4. A single bipolar precordial lead appears to be as reliable for purposes of classifying ECG responses to maximal exercise as the more comprehensive Frank lead system.