LEFT VENTRICULAR ASSIST DEVICES IN THE CALF: 
ANESTHESIA, VENTILATION, ANTIARRHYTHMIC REGIMEN, 
AND IMPLANTATION 
Farouk A. Molokhia, Fred N. Huffman, William J. Robinson, 
Panayiotis J. Asimacopoulos, Ronald B. Ponn and John C. Norman* 
Our initial procedures for LVAD implantation in the 
calf have been complicated by (1) inadequate pulmon- 
ary function during anesthesia, (2) cardiac dysrhyth- 
mias, (3) excessive blood loss and (4) coronary air 
embolism. During our subsequent experience a series of 
adjuncts was evolved to circumvent these problems. 
Calves weighing 91±3.6 kg v/ere premedicated with 0.4 
— 0.8 mg of atropine sulphate. Anesthesia was induced 
with 20-30 cc of 2.5% sodium thiamylal. Intubation 
was often difficult and muscle relaxants were avoided 
until after assisted ventilation had been instituted. 
Anesthesia was maintained at a light plane by in- 
halation of 0.5-1.0% Halothane. The animals were 
ventilated with a pressure-cycled respirator delivering 
50% oxygen at 15 breaths/minute. In the first series of 
calves ventilatory pressures (VP) were set at 15-20 cm 
H=0, resulting in tidal volumes of 1000-2000 ml. In the 
second group of calves VP's were set at 30-40 cm H-O, 
with tidal volumes of 1400-1600 ml. Only in the second 
group was arterial pOr^ maintained at adequate levels. 
The results 150 minutes following induction of anes- 
thesia were: 
pH pC02(mmHg) pO.(mmHg) 
Low VP 7.45±0.04 42.1±6.9 77.5±7.1 
High VP 7.45±0.08 28.9±2.5 228.0±28 
These results indicated that high VP's result in signifi- 
cant (p<0.01) increases in tidal volumes and arterial 
pOs's and acceptable decreases in pCO^'s. The antiar- 
rhythmic precautions employed included preoperative 
correction of potassium deficiencies, the use of lidocaine 
at the beginning of the procedure (80 mglV) as a con- 
tinuous infusion (1 mg/min) and intraatrially (30 mg) 
before intracardiac manipulation, and administration of 
100% O2 during intracardiac manipulation. Ventricular 
fibrillation did not occur in animals receiving this regi- 
men. The implantation technique employed was based on 
that described by Bernhard with modifications. The use 
of a single balloon catheter simplified the original 
method and was combined with CO2 flushing of the pump 
through the inflow tube and CO2 flooding of the oper- 
ative field. These measures have markedly decreased 
blood loss and eliminated coronary air embolism. In our 
experience attention to these details and employment of 
* From the Department of Surgery, Harvard Medical School, the 
Cardiovascular Division, Sears Surgical Research Laboratories, Har- 
vard Unit, Boston City Hospital, Boston, Massachusetts, and the 
Thermo Electron Corporation, Waltham, Massachusetts. 
*♦ Supported, in part, by USPHS Contracts: PH-NHLI-43-67-1116 
and PH-NHLI-43-68-1455. 
these adjuncts have greatly simplified the procedure and 
should be useful to others. 
INTRODUCTION** 
The calf is being utilized with increasing fre- 
quency as an animal model for the development 
of circulatory support systems. The size, ana- 
tomic relationships of thoracic structures, major 
parameters of circulatory hemodynamics and 
the blood coagulation mechanisms make this 
animal especially useful in the development of 
devices for possible use in humans. However, 
investigators using calves for the development 
and evaluation of complex cardiac devices have 
been hampered by the development of pulmo- 
nary insufficiency and the occurrence of cardiac 
dysrhythmias intraoperatively. In the specific 
area of left ventricular assist pump implanta- 
tion, additional problems have been excessive 
blood loss and coronary air embolism. The pur- 
pose of this paper is to summarize our recent 
experience with left ventricular assist device 
(LVAD) implantation in twenty-four calves 
weighing between 80 and 102 kilograms. The 
basic technique employed is that developed by 
Bernhard, with modifications in anesthesia, 
ventilation, antiarrhythmic precautions and 
methods of LVAD implantation and carbon di- 
oxide flushing. 
ANESTHESIA AND VENTILATION 
A major difficulty encountered in our initial 
procedures was severe, uncorrectable hypoxia 
and moderate hypercarbia. This problem was 
approached by (1) general measures designed 
to identify and eliminate from the series ani- 
mals with preexisting pulmonary disease, (2) 
careful selection of an appropriate anesthetic 
regimen and (3) definition and correction of 
intraoperative mechanical factors that might 
result in inadequate ventilation. 
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