개에서 하지동맥 혈류차단후 대상혈로 형성과 동맥 Bypass가 미치는 영향 = Experimental Study of the New Collateral Formation after Dearterialization of the Hindlimb and the Effect of Subsequent Arterial Bypass Grafting In Dog

다국어 초록 (Multilingual Abstract)

Collateral circulation is very important and tissue death distal to arterial occlusion is directly depending on the state of collaterals.
The collateral vessels consist of preexisting collaterals and newly formed collaterals.
The preexisting collaterals are not opening and functioning when the main arterial circulation is intact. But they begin to open and function immediately after interruption of main arterial circulation and also new collaterals develop more and more with the lapse of time.
There are many reports about the study of collateral circulation and the most of them is concerning about preexiseted collaterals.
Although the importance of collateral circulation has long been recognized, the exact mechanism for its development has not been clearly defined.
Several hypotheses have been presented, pressure difference, tissue Po₂, tissue anoxia, altered tissue metabolism and its metabolites, vasodilatation and sympathetic nerve influence in distal tissue.
Many authors have agreed that collateral development is probably resulted from arteriolar dilatations due to decreased myogenic tone of arterial smooth muscle secondary to decreased tissue Po₂, or anoxia and these phenomena occur automatically by autoregulation.
Recently, several discussion is arisen about the fate of collateral circulation after arterial occlusion is relieved by bypass grafting.
The autbors experiment was designed to observe the periodical progression of collateral development after arterial occlusion and the effect of subsequent arterial grafting on already formed collaterals by arteriographies.
To determine the oxygen consumption indirectly, oxygen content was periodically checked in the ligated side deep femoral venous blood and compared with oxygen content in the blood drawn at the same time from aorta and nonligated side deep femoral vein.
A piece of anterior tibial muscle of arterial ligated leg was excised out periodically to examine pathological change.
The experimental dogs were divided into two groups; short term(5 dogs) and long term group(5 dogs).
Right external iliac and common internal iliac artery were ligated and severed. The fine arterial branches around the lower abdominal aorta and initial portion of right iliac arteries were also ligated to interrupt all arterial supply to the right leg.
Short term dogs were examined by periodical arteriography for 4 weeks when arterial grafting with autogenous jugular vein was performed. Long term dogs were left without any experiment for 6 months when arteriography and arterial grafting was performed.
The experimental results were as follows:
1. Collaterals app ared on arteriography about 1 week after arterial ligation. They arose from lumbar and internal iliac artery. After 4 weeks, collaterals developed considerably. Right external iliac and femoral arteries were visualized by the collaterals.
2. After 6 months, collaterals developed numerously. Right external iliac, femoral and even tibial arteries were visualized.
3. The difference of oxygen content of venous blood of ligated side deep femoral vein from oxygen content of aorta and normal side vein was broad in the situation of poor collateral development. The value of oxygen contents were not much different in each sample of blood along with increase of collateral development.
4. There were seen atrophy and fatty degeneration in anterior tibial muscle in early stage after arterial ligation. But the number of arterioles increased per visual field and their wall seemed to be thinner. Although the findings of fatty degeneration improved witb the lapse of time, changes of arterioles became apparent.
5. Most of already formed collaterals disappeared after arterial occlusion was relieved by bypass grafting. The oxygen content of ligated deep femoral vein became almostly same as normal side.
Author's experiment suggested that disappearance of collaterals was probably due to the abolished tissue oxygen demand resulted from sufficient arterial supply to distal leg through arterial bypass grafting.