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KMID : 0378019810240060093
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New Medical Journal
1981 Volume.24 No. 6 p.93 ~ p.100
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Experimental Atherosclerosis Produced by Iliac-Caval Arterio-Venous Fistula
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Abstract
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Ongoing atheroscleroses bring about thickening and loss of elastisity of arterial walls and eventually produce arterial occulusion or aneurysmal dilatation.
Although enomous research works are done for discovering the cause, prevention, pathogenesis and treatment of atheroscleroses, they are still controversial.
Only it was proven that hyperlipidemia, hypertension, cigarette smoking and diabetes are the significant risk factors that predispose to atherosclerosis. 17)
Recently a number of investigators proposed a hypothesis that the lesions of atheroscleroses are initiated as a response to some form of injury to arterial endothelium.
They induced experimentally endotherial injury in models of mechanical, 11,14,18) hemo
dynamic,1,4,7,8,9,15,19,20,21,22,23) irradiation and chemical´ insult on ateries. Then they observed fragmentation of the endothelium, migration of smooth muscle cells from media to intima, shedding of endothelial cells and thrombi formation occur to produce the characteristic intimal artherosclerotic lesions in the experimentally injured artery.
The present experiments were to attempt to detect the early structural changes in vibrated arterial segment of arteriovenous fistula in 3 month old rats.
A typical arteriovenous fistula was constructed by end to side anastomosis of distal common iliac artery to the inferior vena cava under the optimal aid of 4 times magnifying operating loupes.
Experimental animals were killed 1 week, 2 week, 4 week and 6 week after the experimental procedures and the distal portion of the shunted iliac artery segment was obtained for light microscopic examination. Arteriography or saline infusion was done to check the shunt patency.
Pulse vibration was detected at the fistula site in the vena cava using Force-transducer (Fig. 1).
The contralateral left iliac artery was used for control studies. The experimental results were as follows.
1. All iliac artery segments were vibrating vigrously when opened to get specimen. Apparently the shunted iliac artery segment showed much thickened arterial wall (Fig. 2).
2. The pulse vibration detected by Force-transducer at the shunt site in vena cava wa; 260 beats per minute.
3. All contralateral left iliac arterial segment showed unremarkable findings.
4. The findings of intimal thickening and shedding were seen prominently in 2 cases out of 8 rats of 1 week experimental group (Fig. 3).
5. The finding of focal fibrin deposit around eccentric intimal proliferation with above findings were seen prominently in 2 cases out of 7 rats of 2 week experimental group (Fig. 4)
6. The 4 week experimental group showed more thickened intima and eccentric endothelial proliferation with subsequent luminal narrowing. 4 out of 7 rats showed prominently these findings (Fig. 5).
7. 5 out of 7´rats of the 6 week group showed eccentric luminal narrowing with thrombus formation, intimal thickening and subendotheilial proliferation. There were seen mononuclear cell infiltration in the thrombus.
One of these experimental animals showed calcified organized thrombus (Fig. 6, 7).
8. The rate of positive findings consistent with atherosclerotic lesion was increasing along with the prolongation of experimental period. The overall rate of positive findings were about 45% (13/29) in this experimental studies.
9. The author foundd that blood flow vibration produced by arteriovenous fistula could be a factor initiating atherosclerotic `lesions in the isolated shunted arterial segment.
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