That's kind of a "shotgun" question, I'll give you a "shoot from the hip" answer. The blockage isn't sudden, this is over time so as gradually as the resistance builds the heart is doing things to compensate. It pushes harder to get it out therefore the muscle is getting bigger, this requires more O2, and more and more over time. Usually the supplying vessels will engorge to allow more flow, but remember the opening to them is on the outside or "behind" the blockage, so this might not happen as much as it could to help out; there is one aspect of the "off-balance" supply and demand. With the stenosis sometimes the anatomy can be altered so that the opening to the coronary arteries doesn't function perfectly the way they were intended. A lot of this flow depends on the valves working right to "snap" with back pressure on closing and providing that push at the end of a cycle, the way a IABP augments flow. So low coronary filling pressures, and add an elevated rate... killer. Also, there is the internal stress inside the heart trying to push the load through, high internal pressures, stress, and the end result of the fluid backing up every where, a lot of work and stress. On top of all of that is the alterations to picking up of O2 by "drowning" alveoli, hence ischemia.
Does this patient meet any of those risks? If so what would you use instead, if not why?
My cut-offs are usually an open globe injury, hx of serious glaucoma, high K incidences, hx of MH, hmmm.... I think that's it, hard to remember unless you throw something in front of me that turns a switch on somewhere. Relative ones, or the ones I really don't think about are kidney, liver, heart disease? If I'm using succs it's usually because death is near. I have short transports times and people are using CPAP on both ends now. I guess liver being what you're looking for maybe? Pregnancy is in there somewhere I think? If I go off of my ATLS stuff I'd say I'd use it if mom needed an airway anyway.