COMPUTED ST FORCES OF FRANK AND BIPOLAR EXERCISE ELECTROCARDIOGRAMS

1. 1. Simultaneous CB5 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 CB5 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 CB5 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 ST2 locus at rest and during most of the recovery and at ST1 locus during strenuous exercise and immediate recovery. During the second and third minute of recovery, there was no correlation between spatial and bipolar ST3 forces. 3. 3. Most of the ST2 information related to the bipolar lead was located in the X lead of the Frank lead electrocardiogram. A satisfactory correlation between observed bipolar ST2 and predicted bipolar ST2 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. © 1969.