1.

1. Thirty patients with rheumatic heart disease were given 249 roentgen irradiations over the cardiac area. The machine setting was calculated to yield about 10 per cent of the erythma dose distributed throughout the heart muscle. In addition to noting changes in clinical condition, frequent electrocardiograms and numerous teleroentgenograms were made.

2.

2. Following irradiation, changes in the form of the electrocardiogram were observed in 17 of the 30 cases. It is believed that these changes were due to the effect of irradiation on the myocardium, with modification of the rheumatic lesions.

3.

3. Of the 30 cases, 21 (70 per cent) showed clinical improvement at the end of the follow-up period. Three improved temporarily, '1 was unimproved, and 5 died. Those cases terminating fatally were all instances of continuously active rheumatism, with advanced lesions and progressive cardiac failure.

4.

4. In 5 of 7 patients with paroxysms of severe heart pain, relief from this symptom followed roentgenotherapy.

5.

5. Early cases, in the first attack of rheumatic fever, offer the best chance for success in therapy. In a number of cases with low-grade infection, predominantly cardiac, it appeared that the infection subsided following roentgenotherapy. It seems likely that at least one series of four treatments is necessary to initiate improvement. More prolonged therapy is probably desirable.

6.

6. No changes were observed in the teleroentgenograms which could be ascribed to the effects of irradiation.

7.

7. Unpleasant symptoms were noted in 14 cases. These were due, for the most part, to radiation reactions. In no instance was there evidence of injury to the heart or an unfavorable effect on the course of the disease.

8.

8. In 4 cases of subacute bacterial endocarditis due to nonhemolytic streptococcus, roentgen irradiation of the heart caused no change in the form of the electrocardiogram, nor did it arrest the fatal progress of the disease.

9.

9. It is suggested that in rheumatic fever, roentgen irradiation of the heart may serve to desensitize the tissues of the heart to an allergizing substance, thereby favoring the subsidence of existing lesions and preventing further cardiac damage.

10.

10. In patients having their first attack of rheumatism, irradiation may be useful in minimizing the danger of damage to the heart.