The Effect of Radiation upon the Heart

Abstract

Twenty-six patients were investigated clinically, radiologically and electrocardiographically, before and after radiation. The position of the heart relative to the beam of radiation was demonstrated radiologically and the dose received by the left ventricle was calculated. When the left ventricle received a dose of between 2,200 and 3,200 r in three weeks, electrocardiographic changes limited to the T wave occurred and indicated organic injury to the myocardium. This injury was temporary and the lesion behaved in an entirely innocent way. Pre-existing cardiac disease of severe degree may possibly be permanently worsened and it may be thought better to subject such patients to radical surgery rather than radio-therapy. From dissections, an intimate relationship between the heart and internal mammary lymphatics was seen in the majority of cases. In these it appeared that radiation, either by the “glancing” technique or by the use of a direct field over the internal mammary lymphatics would, unavoidably, deliver to the left or right ventricle a significant dose of radiation if the lymphatics were treated adequately. On dissecting some specimens, and radiologically in one patient, a wedge of lung tissue was seen lying between the lymphatics and the heart. In such cases this lung tissue was probably responsible for protecting the heart against receiving sufficient X rays to cause electrocardiographic change.