2. LAD occlusion: the lesion can not be crossed with the pressure guidewire - the lesion is crossed with a standard coronary guidewire, a dual-lumen microcatheter (NHancer Rx Dual Lumen Micro Catheter, Interventional Medical Device Solutions) is positioned distal to the occlusion, backflow is obtained and CWP measurement is performed, through the micro-catheter only if the occlusion persists. A pressure guidewire is introduced through the over-the-wire lumen of the micro-catheter and CWP is again recorded.