Corrected orthogonal electrocardiographic records were taken from 510 normal male subjects. Their age ranged from 19 to 84 years. Data processing and analysis were performed by means of a digital computer. Measurements were taken from the three scalar orthogonal leads and from a variety of spatial vectors in a Cartesian reference frame. Main emphasis was put on series of instantaneous vectors of the QRS complex, the ST segment, and the T wave. In order to eliminate inter-individual variability in electrocardiographic wave durations, time normalization was applied by dividing QRS, ST, and T into equal parts in time. Results for instantaneous vectors were also obtained in absolute time at intervals of 0.01 second. In addition, time integrals, polar vectors, and Eigenvectors were determined for P, QRS, and T. Normal ranges were computed for both normally and abnormally distributed results.

A case of ventricular fibrillation is presented which occurred during retrograde left heart catheterization and preparation for aortography. Direct arterial pressures were recorded from a catheter in the abdominal aorta during closed-chest cardiac massage. These indicated that substantial blood pressures can be readily produced by this simple and practical method.