I'm Reading My Father's Heart Cath Report And Have A

I'm reading my father's heart cath report and have a couple questions before we go back to his doctor. "The left anterior descending coronary arty is transapical vessel. In the mid vessel, it has severe calcification over about 13 mm length with an 80 - 90% stenosis and possible a subtotal occlusion with recanlization. " I get everything except the possible subtotal occlusion with recanlization? Thank you