Hemodynamic significances of chronically total occluded coronary artery

There are limited data on hemodynamic information of chronic total occlusions (CTO), especially in vivo. CTO has usually the collaterals. Factors associated developing collateral arteries are the severity of coronary artery stenosis, the duration of symptoms of myocardial ischemia and the blood pressure. And the hemodynamic information around the CTO are critically important to design the micro-robot system. So, this study aims to define the wedge pressure distal to CTO lesion comparing to non-CTO lesion. We used pressure wire for measuring distal wedge pressure change. We have enrolled 18 patients with CTO and 21 patients with significant coronary stenotic (non-CTO) lesions for scheduled percutaneous intervention. All the procedures were performed after successful guidewire crossing or pre-dilation with 1.5-2.0 balloons. The wedge pressure across the CTO lesion was measured for 1 minute to identify the pressure change after ballooning. The wedge pressure was higher initially in CTO than non-CTO (24.3 vs. 12.8 mmHg) and even increased insidiously during wedging periods. The rate of increasing pressure during wedging was well associated with the collaterals' grade. In conclusion, CTO lesion has higher wedge distal pressure and the collateral flows might be the mechanism of increased wedge pressure.