What Causes Difficulty In Swallowing Post Triple Bypass Surgery?

Patient having trouble swallowing after triple bypass surgery. No problems with swallowing before surgery. He is on a feeding tube, now able to eat some soft blended food. The goal is to wean him off feeding tube. Is this possible, if so how long does it take? Also why did he have swallowing difficulties after this surgery? Do you think it may have been caused by tube insertion which may have weakened his throat muscles?