THE FACTORS DETERMINING THE DIRECTION OF THE T WAVE: THE EFFECT OF HEAT AND COLD UPON THE DEXTRO- AND LEVOCARDIOGRAM

Abstract

The surface of each ventricle (dog) was heated and cooled by means of a thermal chamber placed on the heart. Characteristic alterations in the T wave were produced, together with prolongation of the QRST interval when the surface of either ventricle was cooled. The mechanism of these alterations was further studied by obtaining dextro- and levocardiograms under conditions of heating and cooling. These were obtained by covering the surface of 1 ventricle with pledgets soaked in M/5 KCl soln., while the opposite ventricle was heated or cooled. Heating shortened the dextro- or levocardiogram, and altered the contour; conversely cooling lengthened the complexes and also changed the contour. When the altered dextro- or levocardiograms were summed with normal opposite complexes the resulting T wave corresponded with those actually obtained by heating or cooling either ventricle. The T wave of the electrocardiogram is produced by the summation of the terminal portions of the dextro- and levo-cardiograms.