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 digital computer program for automatic recognition of electrocardiographic waves has been described. First, a filtering procedure was applied in order to eliminate extraneous noise. Consequently, the spatial velocity derived from three orthogonal electrocardio-graphic leads was determined for an entire cardiac cycle. It was found that a critical value of 3 µV per msec, was never exceeded during T-P intervals, P-R segments, and S-T segments. This limit for the spatial velocity could be used to indicate the beginning and end of electrocardiographic waves. The method was tested in a series of 395 records. The computer failed in 1.3 per cent of all expected measurements. "With one exception, failures were encountered only in eases with cardiac arrhythmias but not with regular sinus rhythm. Comparison between computed and visual time measurements showed close agreement, especially when limits of visual accuracy and beat-to-beat variations in wave duration were taken into account. The described procedure can serve as the basis for a complete electrocardiographic analysis by digital computer.
TECHNICS IN ELECTROCARDIOGRAPHIC DIAGNOSISfor reticulocyte levels and red cell FeS9 incorporation showed that both increased as the dose was augmented, h i t reticulocyte response gave more variable results especially a t lower dose levels in the transfused rats. This variability, thought to result from the method of reticulocyte counting, restricts use of this parameter to assay of relatively high doses of erythropoietin. Although measurement of red cell iron incorporation provided a simple and reliable means of measuring both high and low doses of erythropoietin. the amount of blood required for determination of Fe.5!) incorporation a t the dose of radioiron employed precluded the use of a single animal for serial determinations.The dose-response analyses in these esperiments were similar to those of Garcia and Yan Dyke (3) and Hodgson ct ul.( 5 ) in that the relationship between the log of the dose of urine concentrate or plasma extract in niilliliters and the erythropoietic response was linear. Schleuter r t oZ.( 1 2 ) found a sigmoid relationship between Fe;!' incorporation in erythrocytes of starved rats and the log dose of purified erythropoietin obtained from anemic sheep plasma. Within the range tested in the present study a sigmoid dose-response relationship was not noted.In a digital computer program for automatic analysis of electrocardiograms (ECG) a screening procedure for separation of normal arid abnormal records appears an essential preliminary step. A more detailed analysis of pathological tracings may then follow. Since the ECG consists of several distinct wave forms (P, QRS and T waves) with different electrophysiological significance a single screening procedure should preferably encompass analysis of all electri-*This work was supported in part by a grant from ,4m. Heart Assn. cal processes which accompany each heart beat. The spatial ventricular gradient (SVC) appeared as the most comprehensive single parameter known for this purpose. Wilson et aZ.( 1) developed the concept of V8. It has been defined as the net electrical effect of the differences in time course of ventricular depolarization and repolarization. As predicted by simple theory, the time integral (A) of depolarization potentials of a muscleshould be equal to those of repolarization but with opposite sign. For the ECG, the sum of the time integrals of QRS and T should be
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