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://macorners.shop/product-category/heart-puzzle-keychain-gift-box/