放射線照射による慢性心障害について—5症例の検討

Chronic heart disease caused by irradiation:A study of five cases

　放射線心障害は放射線の照射総量が4000rad以上の症例に認められ^1,2），照射量が増すほどその頻度は高くなる^3）と言われている。この心障害には，心嚢液貯留を伴う急性あるいは慢性の心外膜炎や，稀に収縮性心外膜炎，心内膜と心筋の線維化による拘束型心筋症が報告されている^1,2,4〜6）。我々は放射線心障害を疑った5症例について検討したところ，放射線照射後に右脚ブロックや心嚢液貯留を伴った慢性心外膜炎を示す例が多く，放射線に抵抗性があると言われる心筋にも組織学的に病変を認めたので報告する。

Five women were studied for the evaluation of chronic heart disease induced by irradiation for the treatment of breast cancer or rid osteoblastoma. Total dose of irradiation were over 5000 rads for all patients ; one received X-ray with 6 milion electron volt (MeV) and the others electron-beam with 18 to 20 MeV. The time of onset of cardiac symptoms such as shortness of breath, chest oppressive feeling and palpitation ranged from 18 months to 13 years following irradiation.

By computed tomography of the chest and cardiac catheterization, one patient was diagnosed as ha-ving constrictive pericarditis with chronic pericardi-al effusion and other three as having chronic effusive pericarditis. The thickening of anterior pericardium was also noted in these four patients. On electro-cardiogram complete or incomplete right bundle branch block (RBBB) was observed lately after irra-diation in three patients, and nonspecific ST-segment depression and T-wave abnormality were noticed in the patient with constrictive pericarditis.

Endomyocardial biopsy of the right ventricle in four patients revealed nonspecific pathological fin-dings : hypertrophy and disarrangement of cardiac muscle cells, variably sized nuclei of the cells, rare-faction of myofibrils, slight interstitial fibrosis with infrequent cellular infiltration. The functional abnor-mality of the heart in the patient with constrictive pericarditis was completely abolished after pericar-diectomy. The marked pericardial effusion in patients with chronic effusive pericarditis disappea-red by the additional administration of corticoste-roid hormone to diuretics.

In conclusion, RBBB, chronic effusive pericarditis with pericardial thickening and pathological abnor-malities of myocardium were relatively frequently observed following mediastinal irradiation. A long-term observation is needed for the evaluation of radiationrelated heart disease.