Radiotherapy for ablation of ventricular tachycardia: Assessing collateral dosing

Ablation of cardiac tissue using focused radiotherapy to control ventricular tachycardia (VT) is a novel therapeutic consideration in the management of ventricular arrhythmias associated with structural heart disease. Segments of ventricular myocardium that act as substrates for ventricular tachycardia can be identified by the use of invasive mapping techniques or non-invasive ECG incorporating multi-electrode body surface recordings and cardiac imaging. Early case series have demonstrated a consistent decrease in VT burden and sufficient acute safety to expand to more detailed multicenter studies. As VT substrates can be closely related to critical structures such as the epicardial coronary vessels and the conduction system, the late effects of radiation to these structures is of concern. Modeling radiation dose to these structures has a potentially important role in application of this new technology. This review details the current technique of stereotactic body radiotherapy for control of VT and provides approximated dose calculations to collateral structures when therapy is targeted at the base of the heart.