684 
PHYSIOLOGY 
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POSTOP 
RECOVERY REJECTION 
Figure 1. — Changes in left ventricular internal trans- 
verse diameter and diameter shortening in four 
orthotopic cardiac grafts immediately after trans- 
plantation, on the third postoperative day (recov- 
ery) , and during acute rejection. 
Mean QRS voltage in lead II as a function of 
the initial postoperative recording showed a 
progressive decline during the course of acute 
rejection (Figure 2). A decrease in voltage ap- 
peared one to four days prior to death in indi- 
vidual dogs, but the decline in mean values at- 
tained statistical significance only one day before 
death. 
Average heart rate, excluding one dog with 
transient atrial fibrillation, declined only 
slightly during rejection (p > .05) . Stroke out- 
put, however, diminished significantly (p < 
.05) during advanced rejection (Figure 2), and 
terminally reached a mean value of 5.9 ml (±: 
1.3 S.E.), or approximately 50% of the mean 
stroke volume previously recorded at the point 
of maximum hemodynamic recovery after trans- 
plantation. The progressive decline in stroke 
volume accounted almost entirely for the fall in 
cardiac output with rejection (Figure 2) ; mean 
cardiac output decreased late in rejection to 35 
ml/kg/minute (± 3.9 S.E.) or 45% of the pre- 
viously achieved average highest cardiac output 
for all dogs (p < .05). Mean arterial blood 
pressure remained relatively stable, despite the 
deterioration of cardiac output, until terminal 
collapse of the animals (Figure 2). Similarly, 
peak left ventricular dp/dt was well maintained 
during rejection in three of the four dogs stud- 
ied ; in the fourth subject, peak dp/dt, measured 
immediately before death, was decreased in 
comparison to previous recordings (Figure 1). 
End-diastolic diameter showed only slight 
variation during rejection in the four animals 
studied (Figure 1). The small changes which 
did occur were inversely related to individual 
variations in heart rate, although mean heart 
rate during rejection was not significantly dif- 
% QRS 
VOLTAGE 
HEART RATE 
(beats/mm) 
STROKE VOLUME 
(ml /beat) 
CARDIAC OUTPUT 
(ml/kg/min) 
MEAN Art P 
(mm Hq) 
ICQ 
75 
50 
25 
130 
105 
SOL 
15- 
10- 
5- 
100 
75 
50 
25- 
0- 
100 
75 
50 
25 
Post-Op 
Recovery 
_l_ 
_l_ 
72 60 48 36 24 12 
TIME BEFORE DEATH 
(hours) 
Figure 2. — Mean values ± S.E. for QRS voltage in 
lead II (as percent of initial recording) and for he- 
modjTiamics in ten dogs at the time of maximum he- 
modynamic recovery (second or third postoperative 
day) and during acute rejection. 
