外科的完全房室ブロツクに関する研究

Studies on the surgically induced complete heart block.

　直視下心臓内手術の発達に伴い，心臓中隔欠損の閉鎖手術もさかんに行われているが，この際予後に重篤な影響を与える合併症のひとつとして完全房室ブロツクの発生があげられる。Lam^1）2）は53例中9例に，Allen^2）は165例中19例に，Effler^3）は55例中7例に，Cooley^5）37）は10％にブロツクの発生をみている。またBurchell^6）は術後死亡原因の第5位に完全房室ブロツクをあげ，これが死亡原因の8％をしめるとしている。木本外科教室においてもFallet氏四徴症の根治手術に際し，高位心室中隔欠損部直接縫合閉鎖によつて完全房室ブロツクを発生し患者は適切な管理により軽快退院したが，ブロツクは永続性であり，退院後6カ月でおそらく心因性と思われる症状で突然死亡した1例を経験している。

　完全房室ブロツクの本態に関してふるくから知られている。臨床的には症例報告^7-10）や数十例における統計的観察^11-22）が行われており，実験的にはErlanger^23-26）等，SwarthoutおよびEyster^2），Starzl^28）29）等の研究がみられるが，その血行動態および治療法に関する詳細な報告はすくない。

The author performed the surgical production of the complete heart block in dogs and studied the hemodynantics of it, the effects of the electric pacemaker and Isuprel upon the complete heart block.

1) Heart rates and cardiac outputs were remarkably decreased, arterio-venous oxygen differences were increased, venous pressures rose, and the congestion in lungs and liver and bilateral heart failure were found immediately after surgically induced complete heart block.

2) Although heart rates were remarkably decreased in long survivals, the recovery over 80 % of preblock values were obtained in outputs. The author considered that it is not always good in prognosis-to be found the congestion in the liver even though the clinical signs of the heart failure were not seen.

3) Mortality rate due to occurrence of the complete heart block is very high. Over the fifty per cent of dogs died within 3 days after operation and 77.4 % died before one week after surgical production of the complete heart block. And the decreasing tendancy of the motality is found in one week after operation.

4) It is very effective to make heart rate frequent in acute studium of the complete heart block by electric pacemaker. And great increases in output and fairly good improvements in hemodynamics were obtained. The mortality of the group applying the electric pacemaker is 0 %, while that in the group not applying it is very high. The direct myocardial stimulation is the most accurate and effective. The optimal freouency was 100-150 per minute and made the maximal output.

5) The administration of Isuprel increased heart rate 5-20 beats per minute and its effects continued 30-60 minutes. But the author could not expect the sufficient effects only by Isuprel and considered that it is desirable to utilize properly the electric pacemaker with Isuprel as the therapeutic procedure of complete heart block.