CLINICAL PATHOPHYSIOLOGICAL STUDIES ON THE MEASUREMENT OF RIGHT VENTRICULAR EJECTION TIME AND MECHANICAL EFFECT. II. METHOD OF MEASURING THE AVERAGE PULMONARY ARTERIAL PRESSURE AND MECHANICAL EFFECT DURING THE RIGHT VENTRICULAR EJECTION TIME

Abstract

METHOD OF MEASURING THE AVERAGE PULMONARY ARTERIAL PRESSURE AND MECHANICAL EFFECT DURlNG THE RIGHT VENTRICULAR EJECTION TIME Many papers have been written on the measurement of ventricular mechanical effect. The study in this part was undertaken to observe the value of the mechanical effect per unit of the ejection time on the basis of the right ventricular ejection time measured in the previous part and to compare the result with other methods which are generally adopted. Material and Calculation 1 ) Sub jects The subjects are the same as in Part I. The cardiac output which was calculated by the Fick's method on 12 subjects was 9.34 l/min. at the maximum, 3.28 l/min. at the minimum, and 6.68 l/min. on the average. The mean pulmonary arterial pressure was 1 9 mmHg at the maximum and 6.5 mmHg at the minimum, with the average of 13.4 mmHg. 2) Calculation method of the mechanical effect of the right ventricle A. Calculation per minute i) Calculation of the right ventricular work against pressure by Dextor W(Dexter)=(C.I. × 1.055)(P^-pa ×13.6) /1000 kg/min/M2 where C.I. =cardiac index in liters per min per square meter body surface, 1.055 = specific gravity of blood, P^-pa=mean pressure in the pulmonary artery in mmHg, and 13.6 =specific gravity of mercury. ii) Calculation of right ventricular cardiac index Cardiac Index=Mean pulmonary arterial pressure × Heart rate iii) Calculation of myocardial tension = PP^-p × 13.6 × 1.05 ×980/10 × 1.05 × 3√S/3.2 × Heart Rate dynes per cm, where S=stroke volume cc. B. Calculation with the use of the systole or ejection time (TE) as a factor The above-mentioned three methods of do not include the conception of the ejection time. Meanwhile, it is during the poriod of ejection or the period when ventricular pressure ejects blood against the arterial pressure that the heart actually does the pressure work. Sarnoff tried to express the myocardial mechanical effect by putting the systole into consideration.