When intravascular ultrasound becomes indispensable in percutaneous coronary intervention of a chronic total occlusion

Percutaneous coronary intervention of chronic total occlusion is a particular interventional area which requires high level of operator's experience and the support of additional tools based on intracoronary image such as intravascular ultrasound in many cases to clarify difficulties during procedures and to increase success rate. Implantation of long stents in many cases, the presence of stump ambiguity, and the use of specific techniques in this kind of interventions, such as reverse controlled antegrade and retrograde subintimal tracking (CART) and reverse CART make necessary in many cases the use of intravascular ultrasound for a better understanding of the situation, for reducing eventual complications and increasing procedural success rate. We made a review of literature related to most challenging situations in which the use of intravascular ultrasound during chronic total occlusion percutaneous coronary intervention becomes rather indispensable to safely continue and finish the procedure. Besides, two complex percutaneous coronary interventions of chronic total occlusion with unfavourable anatomic features in which intravascular ultrasound was crucial for the procedural success are presented in this manuscript along with support of the literature.