WASHINGTON — The nation’s death rows are starting to look like geriatric wards. Condemned inmates in many states are more likely to die of natural causes than to be executed. The rare ones who are put to death often first spend decades behind bars, waiting.

It turns out that executing old men is not easy. In November, Ohio called off an attempt to execute Alva Campbell, 69, after the execution team could not find a suitable vein into which to pump lethal chemicals. The state announced that it would try again in June 2019, by which time he would have been 71.

But Mr. Campbell suffered from what one judge called an “extraordinary list of ailments.” He used a walker, could barely breathe and relied on a colostomy bag. He was found lifeless in his cell on Saturday, having died in the usual way, without government assistance.

In Alabama last month, state officials called off the execution of Doyle Lee Hamm, 61, also because they could not find a suitable vein. Mr. Hamm has at least two kinds of cancer, cranial and lymphatic, and he may not have long to live with or without the state’s efforts.