The spatial vectorcardiogram in left ventricular hypertrophy.

A study of 90 patients with left ventricular hypertrophy revealed a typical configuration of the spatial vectorcardiogram in most of the subjects. Typically the QRS stY-loop was smooth, wide and rounded, inscribed in a counterclockwise direction and placed largely to the left and above the iso-electric point in its frontal plane projection. The left sagittal plane projection of the QRS stY-loop was long, narrow and directed largely upward and posteriorly. The typical T stY-loop was small, smooth, horseshoe-shaped and counterclockwise in inscription in both frontal and left sagittal plane projections. In some instances the QRS stY-loop was similar to that of the normal but was always accompanied by an abnormal T sti-loop. T HE electrocardiographic features of left ventricular hypertrophy are frequently not clearly separable from those produced by cardiac position and by abnormalities of the myocardium other than hypertrophy. On the other hand, subjects demonstrated to have left ventricular hypertrophy by other methods of examination may have a normal electrocardiographic configuration of the QRS complex with or without T-wave abnormalities. The following study was undertaken to provide a description of the spatial vectorcardio-gram in left ventricular hypertrophy recorded with the equilateral tetrahedron reference system and to investigate its possible role in making these distinctions. Others have studied left ventricular hypertrophy with other reference frames.'-5 MATERIALS AND METHODS The 90 patients with left ventricular hypertrophy studied ranged in age from 27 to 80 years, and 70 were male and 20 female. Evidence for left ventricu-lar hypertrophy was essentially indirect since only five cases have been followed to autopsy thus far (table 1). Cases were selected on the basis of clinical, roentgenographic and electrocardiographic study from patients with diseases which commonly result in left ventricular hypertrophy. Spatial vectorcardio-728 grams were recorded, using the equilateral tetra-hedral reference system and cathode ray oscilloscopes. Projections on the frontal, right, left and superior planes were each photographed simultaneously with a projection on the plane sagittal to each as viewed from the subject's left. Stereoscopic views of the frontal, left, right and superior planes were also recorded. Records were also obtained with the amplification increased to obtain adequate delinea-tion of the T st~-loop and junction J from the iso-electric point. The standard leads, V, through V,, unipolar limb leads and a unipolar lead from the back and bipolar leads from the back electrode and each of the other electrode positions defining the equilateral tetra-hedron were recorded …