There are other ways to inject IV drugs, like into arteries and surgically installed lines. The death row medics don’t have the training or practice to do that.
No, surgical nurses are well trained and quite experienced at starting IV’s. They do it many times each day, so they know what they’re doing.
The other side of the coin is that we don’t want it to be too ugly, either. If you want fast and painless, an expanding-bullet rifle shot through the brain will do it… but it leaves a real mess behind.
Dumping the prisoner head-first into an industrial-size wood chipper would be ugly too, but over in just a second – Probably fast enough to be considered humane (except the ugliness would prevent that).
Why is it necessary to use a drug to stop the heart? Why not just use a massive overdose of an opioid? Blood pressure drops until death occurs.
A. What makes you think anybody bothers to report about such cases?
B. In a hospital, you have experienced, trained professionals with a large variety of equipment. At an execution you have some clown off the street and nothing remotely like the equipment you have in an OR.