乳児先天性心疾患の肺の組織学的検討—肺血流量増大をともなう心疾患群の末梢肺動脈の変化

Histological Study of the Pulmonary Arterial Tree in Congenital Heart Diseases under One Year of Age:Ventricular Septal Defect, Atrial Septal Defect and Patent Ductus Arteriosus

緒言

　乳児先天性心疾患の外科的治療の進歩とともに，その病態，外科的手術適応の決定が一つの重要な問題となってきた。このような観点に立ち，肺血流量増大をともなう乳児心疾患の肺高血圧の病態を知る一助として，これら乳児心疾患剖検例の肺末梢血管の変化を組織学的に検討したので報告する。

The rapid development of surgical techni-ques for the correction of cardiovascular defects in infancy has increasingly focused attention on the pulmonary vascular tree, the integrity of which is of fundamental importance in the result of corrective surgery of the heart.

The data in this report are based on his-tological findings of the pulmonary arteries in 24 autopsied cases including 13 cases of VSD, 4 cases of PDA and 7 cases of ASD under one year of age. As controls the lungs in 20 cases without any evidence of cardiac or pulmonary disease under one year of age were used.

Each lobe was used for the histological study of the pulmonary vessels. They were stained with both hemaloxylin-eosin and Weigert's elastica-van Gieson stains. The classification of pulmonary arteries suggested by Brenner was not employed in this work, for diameter of the pulmonary arteries are smaller in infant than in adult. So the main criteria employed in the recognition of the arterioles and the muscular arteries are not the diameter of svessel but the structure of their walls. The histological findings of pulmonary arteries were classified by the Heath-Edwards' description, and the exter-nal diameter, the thickness of the wall and the media were measured in the pulmonary muscular arteries and the arterioles.

In the control group the wall thickness/lumen diameter ratio in the pulmonary mus-cular arteries (W/L×100) were 14 to 33 (average, 18) in one month after birth, but they decreased gradually and after 3 months they became about 10. Comparing with the control group, these of the congenital heart disease were 9 to 31 (average, 18) in onemonth of age, but they did not decrease in many cases following the months after birth. The same relation was observed in the thickness of media/diameter ratio (M/D×100) in the pulmonary muscular arteries. And these medial hypertrophy was the most prominent in the group of ventricular septal defect.

In regarding to the pulmonary arterioles the wall thickness/lumen diameter ratio (W/L×100) in control group were 12 to 35 (average, 23) in one month and gradually decreased. But in the congenital heart dis-ease group the decrease in the ratio was small, and in two cases the intimal prolife-rations were sever. But plexiform or glome-rulus-like structure were not examined.

According to Heath-Edwards' description these histological changes of the pulmonary arteries in congenital heart diseases would be classified as 22 cases of grade 1 and 2 cases of grade 2.

The medial hypertrophy would he caused by delayed maturity of the lung or the in-crease of pulmonary flow by left to right shunt following decrease of pulmonary resis-tance after birth. Slight degree of intimal proliferation in many cases under one year of age would indicate that the secondary histological changes due to pulmonary hyper-tention is not serious yet.