Roentgenological Heart Volume Determination with Special Regard to Pulse Rate and the Position of the Body

Abstract

Of the various methods for the detn. of heart volume, the Rohrer-Kahl-storf formula for volume detn. has proven to be the most adaptable for practical use, but the factor included in the formula varies with the heart''s shape and tilt, and must, therefore, be detd. in each case. A method of determining the factor is given. In the prone position, the heart''s volume undergoes no demonstrable change with pulse increases up to 120/min.; in the upright position a diminution in heart volume proportional to the elevated pulse rate takes place. The pulse rate must rise above 75-80/min. before any volume decrease can be observed. The difference in volume between lying and standing positions is not proportional to the difference between the pulse rate in the respective positions, but to the standing pulse rate. On account of the volume diminution which the hydrostatic blood displacement causes in the standing position, it is considered necessary that all heart volume detns. be carried out with the individual horizontal. A simple method for heart volume detn. in the prone position is given. The importance of making all exposures for volume detn. in the same heart phase is emphasized. To determine the heart volume, the exposure should be made at the end of diastole, just before the R wave. However, in the investigation of mitral lesions, the exposure should also be done at the end of the systole at the termination of the T wave.