[et2o]

I wonder why they were so worried about radial artery spasm. If it closes off, you still have sufficient collateral circulation via the ulnar artery. This happens not infrequently in procedures where you catheterize the radial artery.

[ItsMe000001]

They were worried because they thought the margin you normally have did not exist in this case, and they tried to avoid any drop in circulation, which would reduce the amount of fresh calcium brought into the hand, which might not be compensated by the additional artificial supply if the radial artery's flow dropped. In those other procedures that you mention you have a bit more room because normally the tissues are not at their limit of how much of the various molecules supplied by blood they use.

For those unfamiliar with how blood supplies various molecules, some of it solved in blood directly, some of it bound to carriers, most famous probably being oxygen: It's not like in a human supply chain where an empty truck or a train is loaded to capacity and then again emptied completely when it reaches a destination point. Instead, it's an equilibrium that changes based on things like partial pressure or acidity (pH is very slightly more basic in the lungs, slightly more acidic in the periphery, because of CO2 - also see "Bohr effect") and a lot of other variables. There is no 0% or a 100%. Here is an example for a curve for oxygen: https://courses.lumenlearning.com/wm-biology2/chapter/transp...

[et2o]

I'm highly familiar with details of vascular supply.

My point is that you have to weigh benefits of getting calcium there rapidly vs. potential harms of radial artery occlusion.

[ItsMe000001]

> I'm highly familiar with details of vascular supply.

I assumed as much, does that invalidate anything in my comment? I made it fully expecting that you have the knowledge. That's why I prefaced paragraph two with "For those unfamiliar with how blood supplies various molecules...", to avoid that you feel you are the target of a lecture about things you already know very well.

[robbiep]

Not to mention the millions of people who don’t have a radical artery because it has been harvested to use as a coronary artery for coronary artery bypass grafts

[et2o]

Nowadays they usually use the internal mammary artery. But if they did harvest the RA I don't think it would be possible to inject, let alone spasm :)

[robbiep]

That’s entirely dependent on anatomy, and if you need more than 2 grafts you will almost always take a radial, which is particularly common given the high and increasing rates of diabetes in CABG patients, which produces diffuse disease VS couple primary site blockages. Saphenous vein also a common target