4. Presence of interventional collaterals
What is an interventional collateral will vary considerably depending on operator experience. For a beginner operator, maybe only very straight and visible septal channels or large arterialized channels would be considered an “interventional collateral”. As the operator gathers experience, more difficult channels will become interventional collaterals for them. We stress both the importance of “thinking of retrograde” and making a retrograde attempt even for beginner operators as well as the importance of having proctor to prevent retrograde complications.