Advantages of Ventral Position in Recording Electrocardiogram of the Rat

¹ From the New York Medical College, Departments of Physiology and Pharmacology, Flower and Fifth Avenue Hospitals, New York City

The electrocardiogram of the nembutalized rat was recorded with the animal in ‘unrestrained’ prone position. The animal's legs were made to protrude through appropriate cutouts of a Lucite platform into four saline-filled beakers which served as electrode contacts. Conventional leads were inscribed with a Sanborn Twin Beam Electrocardiograph and the frontal plane loop was visualized on the long persistence screen of the Cambridge Cardioscope. The stability of serial recordings and the inscription of tall R waves in lead 1, encountered in all experiments, was interpreted as due to the ventral recording position. Unfavorable cardiac rotation and undesirable variations of the projection of the spatial QRS loop on the frontal plane were considered as possible consequences of other recording positions. It is concluded that the ventral position in recording the electrocardiogram of the rat appears to possess definite advantages over the routinely employed dorsal position.