To determine left atrio-femoral arterial bypass flow requirement during clamping of thoracic aorta,
26 mongrel dogs were used in this experimal investigation. They were divided into five groups.
In group Ⅰ with postsubclavian aorta clamped for 60 minutes but without left heart bypass, left
atrial pressure and left ventricular pressure, histopathologic changes of lung and postoperative course
were observed. In group Ⅱ without aorta clamped but bypassed at 40c.c per kilogram per minute
for 90 minutes, left atrial pressure, left ventricular pressure, histopathologic changes of lung and
post-operative course were observed. In group Ⅲ with post-subclavian aorta clamped and bypassed
at 40c.c/㎏/min for 90 minutes, left atrial pressure, left ventricular pressure, esophageal tem
perature, histopathologic changes of lung and post-operative course were observed.
In group Ⅳ with post-subclavian aorta clamped and bypassed at 60c.c/㎏/min for 90 minutes,
same observation was performed as in group Ⅲ. In group Ⅴ with the aorta clamped and bypassed
at flow rates which maintained left atrial pressure and left venticular pressure at the pre-clamping
leve, esophageal temperature, histopathology of lung and post-operative course were observed.
The obtained results are as follows.
1) Thoracic aorta clamping without bypass in mongrel dogs resulted in high incidence of left heart
failure and subsequent death deu to excessively increased load on left heart and paralusis of lower
extremities due to anoxia of spinal cord.
2) Left atrio-femoral artery bypass at 40c.c/㎏/min without clamping thoracic aorta did not show
any remarkable load on left heart.
3) In thoracic aorta clamping with bypass at 40c.c/㎏/min, marked hemodynamic load on left
heart was noticed during the initial 30 minutes but during the next 60∼90 minutes it was progres
sively normalized associated with lowering of body temperature.
4) In group Ⅳ the aorta clamped and bypassed at 60c.c/㎏/min, load on left heart was initially
increased significantly but with lowering of temperature it was progressively normalized and at post
clamping 30 minutes it returned to pre-clamping states At postclamping 60 minutes marked decrease
in left atrial and venticular pressures due to the decrease in blood flow of proximal aorta was so
remarkable as to induce coronart arterial insufficiency and subsequent cardiac arrest in some cases.
5) In group Ⅴ with the aorta clamped and the bypass amount regulated to maintain left atrial and
left venticular pressure at pre-bypass level, considering lowering of body temperature (Immediate
post-clamping; 67±10.3c.c/㎏/min, Bypass 90 min; 31±11.0c.c/㎏/min) the best results
with least hemodynamic changes were observed.
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