Radiotherapy Heart Effects

Abstract

Nowadays radiation toxicity is relatively rare; however, patients have to be informed and closely followed up. Risk factors for radiotoxicity are doses, volume irradiated, age at exposure, time from exposure, chemotherapy, and cardiovascular risk factors. Cellular toxicity consists of an acute inflammation cell death with replacement of necrotic tissue by extensive fibrosis.

This process includes all cardiac structures. Coronary disease evolution is severe, quick, and involving proximal tracts. An acute coronary syndrome or sudden death may be the first event. Fibrosis and valvular calcification occur mainly on left-sided valves. Supraventricular and ventricular arrhythmias, sick sinus syndrome, or conduction blocks may be present. Acute pericarditis and large effusions leading to tamponade, chronic effusion, and constrictive pericarditis may develop after variable time from irradiation. The nervous system of the heart can be damaged by RT, altering pain and angina threshold and sympathovagal balance. Myocardial fibrosis leads to diastolic dysfunction with a picture of restrictive cardiomyopathy, and association to anthracyclines can evolve with a systolic dysfunction. Heart failure may be aggravated by concomitant valve and coronary disease. Also great vessels of the neck and other body regions may be involved.

Treatment of radiation-induced diseases is similar to that of the same not radiation-induced clinical expressions, but surgical procedures like a surgical pericardial window, a coronary bypass procedure, or a valve replacement may be very difficult for intense mediastinal fibrosis. Coronary revascularization through interventional cardiology and TAVI may be preferable.

An adequate follow-up of patients submitted to RT is mandatory but is still lacking clear recommendations about timing and method.

The reduction of possible radiation-induced cardiotoxicity may be obtained lowering the dose of radiation and the cardiac volume exposed with different methods requiring sophisticated technologies based on advanced imaging analyses and complex radiation delivery tools.