p. KRAFT-HUNTER AND E. W. HAWTHORNE 
643 
100 
S TROKF WORK / END-DIASTOLIC VOL. 
DOG 132 
VENTRICULAR PACING + CONTROL (11 th P O DAY ) + PROPRANOLOL (0.5 MGMS/KG) 
Y = - 9.65 + 1. 128 X (1) 
Y = - 31.5 + 1.548 X (2) 
Y = - 8.86 + 1.359 X (3) 
Y=- 81.1 +2.184 X (4) 
75 
GM-M 
50 I 
25 
25 
50 
ML 
75 
100 
Figure 10. — Shows the stroke work/end-diastolic relation after injection of propranolol, and provides the regression 
lines from the three previous states as shown in Figures 7, 8, and 9. 
Rapaport, E. The influence of heart rate on left 
1963. 
30. Mitchell, J. H., Gilmore, J. P., and Sarnoff, S. 
J. The transport function of the atrium. Factors 
influencing the relation between mean left atrial 
pressure and left ventricular end-diastolic pressure. 
Amer. J. Cardio. 9:237, 1962. 
31. Berglund, E., Borst, H. G., Duff, F., and 
SCHREINER, G. L. Effect of heart rate on cardiac 
work, myocardial oxygen consumption and coro- 
nary bloodflow in the dog. Acta. Physiol. Scandi- 
nav. 42:185, 1958. 
32. Leighton, R. F., Zaron, S. J., Robinson, J. L., 
and Weissler, A. M. Effects of atrial pacing on 
left ventricular performance in patients with heart 
disease. Circulation 40:615, 1969. 
33. Parker, J. O., Khaja, F., and Case, R. B. 
Analysis of left ventricular function by atrial pac- 
ing. Circulation 43:241, 1971. 
34. Daggett, W. M., Bianco, J. A., Powell, Jr., W. 
J., and Austen, W. G. Relative contributions of 
the atrial systole-ventricular systole interval and of 
patterns of ventricular activation to ventricular 
function during electrical pacing of the dog heart. 
Circulation Res. 27:69-79, 1970. 
35. Samet, p., Bernstein, W. H., Levine, S., and 
Lopez, A. Hemodynamic effects of tachycardias 
produced by atrial and ventricular pacing. Amer. J. 
Med. 39:905-910, 1965. 
36. Herd, J. A., and Barger, A. C. Simplified technique 
for chronic catheterization of blood vessels. J. Appl. 
Physiol. 19: 791-792, 1964. 
DISCUSSION 
G. F. Gestring, Newark Beth-Israel Medical 
Center, N.J. : First of all, I would like to con- 
gratulate you on your beautiful study and excel- 
lent presentation ! There is one question I want 
to put to you. This morning, Dr. Levy showed 
