BackgroundWith the development of specialized equipment and the retrograde technique. success rates for percutaneous coronary intervention (PCI) of chronic total occlusions (CTOs) have increased from 60 to 90% in the past 10 years. Performing PCI via a collateral channel from the contralateral artery. using two guiding catheters. https://www.alarecre.com/Virescent-Harmony-Galaxy-A14-5G-Clear-Case-p106336/