p. KEZDI, S. N. MISRA, R. K. KORDENAT AND T. J. SMITH 
69 
endings. It might be worthwhile to mention that 
atropine did not have the same effect as vagot- 
omy because it only increased heart rate but 
sympathetic activity and cardiac output re- 
mained unchanged (Figure 6). Atropine blocks 
the efferent outflow of the vagus to the heart 
and thus acts on heart rate only. 
Studies of Sympathetic Augmentation and 
Block in Cardiogenic Shock 
In view of the findings that sympathetic ac- 
tivity is not maximal, but actually depressed in 
cardiogenic shock (which probably affects both 
the peripheral resistence vessels and the pump- 
ing force of the heart itself) , and since atropine 
does not seem to reverse this trend, we have de- 
cided to study systematically sympathetic act- 
ing drugs in this cardiogenic shock model. In a 
total of 50 unanesthetized shock dogs different 
alpha adrenergic blocking and alpha and beta 
adrenergic stimulating drugs were tested as to 
their effect on hemodynamics and 24-hour sur- 
vival. Table I shows the experimental groups 
and the drugs tested. Table II shows the direct 
and the derived measurements obtained. These 
drugs were administered several hours after 
the mercury injection when cardiogenic shock 
has developed with 50% decrease of cardiac 
output and the other signs of hemodynamic de- 
terioration as previously shown. 
Group A received phenoxybenzamine to- 
gether with volume expansion according to 
Dietzman and co-workers." Figures 8 and 9 
show that the average mean blood pressure fur- 
ther decreased in these animals with the 
concomitant falling of systemic peripheral re- 
Table I. — Experimental Cardiogenic Shock Groups of 
Dogs Studied 
Group 
No. of 
dogs 
Dose 24-Hour 
Drug administered survival 
A 8 Phenoxybenzamine 
(Dibenzyline) — 1-2 mgAK 1 
Bi 8 Norepinephrine — 2-4 ytig/min 3 
Ba 8 Norepinephrine 4-6 ^g/min 4 
B3 8 Norepinephrine 6-8 ji^g/min B 
C 8 Phenoxybenzamine + - mg/kg 2 
Norepinephrine 8 ^g/min 2 
D 10 Isoproterenol alone 3-4 n/min - 
and 
Isoproterenol + 1 mg/min 6 
Norepinephrine — 2-4 ^g/min 6 
60 
Table II. — Parameters Recorded or Calculated 
Measurement Technique 
ECG 
Aortic pressure — systolic — 
diastolic — mean - Aortic catheter 
Cardiac output (CO) Indocyanine 
green .. _ _ Lexington CO. computer and Tri- 
angulation 
Stroke volume (SV) CO ml/beat 
Left ventricular end-diastolic 
pressure (LVEDP) Catheter 
Left ventricular dP/dt 
mmHg/sec RC differentiating circuit 
Peripheral resistence dynes/ 
sec/cm~^ 
Left ventricular stroke work 
(LBSW) g-m SVx MAP-RAP x 13.6/1000 
Endsystolic volume (ESV) ml . .- Shaffer Indocyanine Green 
Enddiastolic volume 
(EDV) ml Shaffer Indocyanine Green 
Ejection fraction (EF) - SV/EDV 
Modified tension time index 
(PRI) mm Hg per minute - Mean systolic pressure times heart 
rate 
Left ventricular excess lactate 
moles/lit Coronary sinus — arterial lactate 
minus coronary sinus — arterial 
pyruvate times arterial lactate/ 
pyruvate 
Blood volume I^^ tagged albumin 
sistence. The latter decrease was significant at 
the 2% level. Cardiac output slightly increased 
and there was a slight increase of stroke volume 
from the shock level. However, while the aver- 
. Dibenzylene (1-2mg/Kg) — (8 Dogs) 
BASELINE 
H SHOCK 
^ DI6ENZYLENE 
★ N.S. 
HR 
(beats/min) 
MBP 
(mmHg) 
CO 
(L/min) 
SV 
(ml/beat) 
Figure 8. — Hemodynamic changes before and during 
shock and after phenoxybenzamine plus volume ex- 
pansion. HR = heart rate; MBP = mean blood 
pressure; CO = cardiac output; SV = stroke vol- 
ume. Horizontal bars above thick bars are one-half 
standard deviations. The changes between bars are 
significant at the 2% level where no stars are 
present. 
