Radiation-Induced Cardiotoxicity: Experimental Data

Abstract

The myocardium is included in the treatment field of radiation therapy of mediastinal tumors, breast and lung cancer. While early clinical and experimental observations focused on radiation-induced pericarditis, more recent reports show that with modern radiotherapy techniques the incidence of pericardial disease has dropped below 5% (Carmel and Kaplan 1976; Watchie et al. 1987; Morgan et al. 1985). However, increasing survival rates and follow-up times of relatively young patients reveal that heart irradiation can cause chronic impairment of cardiac pump function. Systematic cardiological evaluation of patients 5–20 years after mediastinal radiotherapy for Hodgkin’s disease revealed an abnormally low left ventricular ejection fraction in 4%-29% of the patients (Morgan et al. 1985; Gomez et al. 1983; Burns et al. 1983; Gottdiener et al. 1983; Applefeld and Wiernik 1983; Savage et al. 1990; Gustavsson et al. 1990). Although nearly all of these patients were free of clinical symptoms of heart disease, it is conceivable that latent cardiomyopathy will predispose them to cardiotoxic effects during further tumor therapy and to overt heart disease from other causes. Several experimental models have been developed with the aim of studying the radiobiology, pathophysiology and pathogenesis of radiation-induced cardiomyopathy.