bol. Accordingly, the exercise data points have the smallest numeric coordinates on both the ordinate and the abcissa. Discussion The results demonstrate that the carotid upstroke closely tracks the pre-ejection period and that the carotid incisura closely tracks the aortic component of the second heart sound. The tracking relationships show slopes and correlation coefficients close to 1.00. Figures 2 and 3 show that the data at all points have very little scatter from the regression line. The

more »

... ost scatter was during IHG. This is reflected in its relatively low coefficients. Thus, measurements of CARu and CARIN can be used, respectively, in place of PEP and EMS (IIA) in certain stress tests, with the exception of IHG during which CARu varies with PEP but predicts it to a too limited (64%) extent. Indeed, if the combined series is recalculated without IHG, the overall values improve as shown in the last line of table 1. (The near-perfect correlations for EMS in table 2 make recalculation redundant.) Conversion to PEP and EMS is readily performed by using the data in tables 1 and 2 as regression equations for the appropriate control or challenge state. For PEP, the general formula for this is: PEP -CARua b and for EMS: in which a is the intercept and b is the slope for the appropriate conditions. Since left ventricular ejection time is measured directly, this determination of PEP and EMS appears to bear out the hypothesis of this investigation: Noninvasive measurements of certain stress test responses utilizing the systolic time intervals can be performed without using a phonocardiograph. This has the advantages enumerated in the introduction to this paper.