Intracardiac echocardiography techniques to identify ventricular arrhythmia substrate

Intracardiac echocardiography (ICE) is increasingly used to facilitate catheter ablation of ventricular arrhythmias (VA). It allows intraprocedural recognition of myocardial substrate, optimization of catheter-tissue contact, identification of anatomical barriers to ablation, and early recognition of complications. In the era where the 3-dimensionality of substrate for VA is increasingly recognized, ICE is invaluable in identifying scar topography in the endocardial, midmyocardial, and epicardial layers. ICE assists in identifying endocavitary structures that are a common source of VA in idiopathic and structural heart disease. Furthermore, as substrate imaging of the right ventricle has not been optimized with other imaging modalities, ICE offers a unique opportunity to visualize substrate in this chamber. Real-time substrate identification can be particularly useful where there are contraindications to use of other imaging modalities or the images are obscured by artefact in the presence of cardiac device leads. In this review we provide a step-by-step guide in the techniques used to image ventricular arrhythmia substrate with ICE. We also discuss the benefits and limitations of this technique in comparison to other imaging modalities.