直視下心内手術のためのクエン酸カリウム使用による任意心拍停止および蘇生に関する実験的研究（特にその経過中の心筋代謝について）

Experimental studies on the elective cardiac arrest induced by the administration of potassium citrate.

I．緒言

　近時心臓外科の発達により，直視下心臓内手術が行われ，成功した報告がかなり多数みられるようになつた。これには心臓カテーテル法およびその他の諸検査により異常心の病態がかなり明確に知りえるようになつたことと，化学療法，輸血学，麻酔学の進歩におうところが大であつた。従来生命保持に必須と考えられていた心臓を切開して行う直視下心臓内手術では術中その心臓の機能は中断されるので，この間の患者の管理が最も困難であつた。常温下血行が杜絶してしかも生命を維持できる時聞はわずか5分内外である。この間に確実で充分な心内手術操作は無理なので，この時間を安全に延長する努力が行われた。すなわち循環不全による変化の大なるもので，しかも生命維持に最も大きな影響をもつ臓器として中枢神経系と心臓が考えられ，これらの保護が色々と工夫されて，全身低体温法^1）2），人工心肺^3），選択的脳灌流冷却法^4），選択的冠灌流法^5），人為細動下手術^6）7）など，およびそれらの併用法が行われてきた。

　ここで報告する任意心拍停止および蘇生による手術方法は，中枢神経系その他は人工心肺装置灌流により保護し，心臓を全身循環より孤立させてのちすみやかに拡張期性に停止させて，心筋の代謝を低下させ，冠循環遮断による心筋への影響を減弱し，この間に静止した出血の少い明瞭な手術野で心内操作を行う。

1) Under extracorporal circulation 75 matured mongrel dogs were subjected to the experiment of elective cardiac arrest by the administration of potassium citrate, and the myocardial gas-, electrolyte-and carbohydrate-metabolisms were studied as well as acid-base balance.

The results were compared to those of the control group.

2) During the cardiac arrest, myocardial oxygen uptake and carbon dioxide output were markedly decreased as compared to the control group and to the period of perfect perfusion. On the resume of the perfusion of the coronary system and the rebeat, these gas metabolisms showed a considerable rise from the values at cardiac arrest, though they were still lower than the control group and during the perfect perfusion.

3) Along the course of the experiment, Na, K and Cl of the arterial blood taken from the outlet of the heart lung machine did not show any significant changes when compared to the control group, while Ca showed a significant decrease on the perfect perfusion and remained at the same level thereafter. Potassium of the coronary vein, however, showed a wide change as expected from the use of potassium citrate. The changes in coronary venous Na and Cl were to the opposite direction of the K change, while Ca and Mg were not affected by K and did not show any change.

4) Lactates and pyruvates of both the artery and the coronary vein showed a gradual increase along the course of the experiment, and there was a tendency for the pyruvates to be released from the myocardium during the cardiac arrest and at the rebeat.

5) The arterial blood was gradually inclined to show metabolic acidosis along the course of the experiment.