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February 27, 1967

Determining the Direction of the Cardiac Vectors in the Frontal Plane

Author Affiliations

From the Department of Cardiology, Maine Medical Center, Portland, Maine. Dr. Stinebaugh is presently at University Hospital, Boston.

JAMA. 1967;199(9):665-668. doi:10.1001/jama.1967.03120090107028

VECTOR interpretation of the clinical electrocardiogram is becoming increasingly popular.1-3 This method relates the scalar ECG to the basic underlying electrophysiology and eliminates, in many instances, the need for memorizing multiple abnormal "patterns." The initial step in this approach is to determine the direction of the QRS and T wave vectors. The relationship of these two vectors to each other is called the QRS-T angle, and is a sensitive index of T wave abnormalities.

Although vector analysis of the scalar ECG has been in use for many years, no detailed description is available of a simplified method for localization of the vectors from routine clinical tracings. The purpose of this report is to present such a method.

Method  This approach is a variation of the method of Grant1 and is similar to that described more briefly by Nadas.3 The basic principle of Grants's method is that a vector