Proximal Cap Ambiguity

This article reviews how to approach the proximal cap of a chronically occluded coronary artery. Safely crossing this region of the lesion is a crucial step in the procedure. While many proximal caps are understood angiographically, a significant proportion are not. This article describes steps that can be taken to resolve anatomic ambiguity, either by the use of supplementary intravascular ultrasound or by more advanced maneuvers, which should enhance the safety and efficiency of the percutaneous coronary intervention.