Transthoracic echocardiography (TTE) is the method of choice for pre-procedural assessment of cardiac anatomy and functional status and serves as a basis for therapeutic decision-making in ablation and device therapy. Assessment of ventricular dyssynchrony is of particular importance prior to CRT device implantation. After EP treatment, TTE is essential to detect procedure-related changes in cardiac function, anatomy and complications and – especially after device implantations – to optimize device programming in the acute setting and during periodic follow-up visits. Transesophageal echocardiography (TEE) is recommended for the exclusion of pre-existing thrombi prior to ablations. The ACUSON AcuNavTM V catheter, the world's first real-time volume ICE catheter, offers extensive opportunities for real-time 3D visualization during complex EP procedures.