Updated

Dick Cheney says the gray Stetson cowboy hat he's been wearing lately has to do with the heart transplant he got last year.

The former vice president said Friday he is taking two drugs to reduce the risk of organ rejection. The drugs leave him susceptible to skin cancer, he said, so his doctors tell him to wear lots of sunblock and to put on a wide-brimmed hat whenever he goes outside.

"It's not because I suddenly decided I looked better with a Stetson. There are certain things you have to guard against," he said.

Cheney and his daughter Liz Cheney were in Cheyenne on Friday to promote his book about his struggles with heart disease since the 1970s. Cheney's cardiologist, Jonathan Reiner, co-wrote the book, "Heart: an American Medical Odyssey."

Liz Cheney is running for the U.S. Senate in Wyoming against incumbent Mike Enzi, a fellow Republican. Neither Dick Cheney nor his daughter mentioned politics or political issues in an hour-long luncheon chat sponsored by the Greater Cheyenne Chamber of Commerce.

About 160 people attended the $50-per-plate lunch. Proceeds benefited the Wounded Warrior Project veterans' service organization.

Cheney said the anti-rejection drugs leave him susceptible to infection as well. He washes his hands frequently, he said, and can no longer eat oysters on the half shell or sushi because raw seafood carries the risk of troublesome illness.

He expressed gratitude for getting a new heart, though, after his heart trouble, by 2011, had left him barely able to get the paper from the driveway in the morning.

"I was convinced I'd reached the end of my days," he said.

A small pump installed in Cheney's heart helped him with the wait for a new heart. He said he was on the transplant waiting list for 20 months before getting a transplant in March 2012.

"It was by far the easiest open heart surgery I'd ever had," he said.

Cheney recalled the challenges his heart trouble presented while he was vice president. He said he had the manufacturer of his implanted defibrillator disable its wireless feature out of concern an assassin might be able to start the device remotely.

He wrote and signed a resignation letter, he said, to help with the appointment of his successor in case he died or became incapacitated in office. The Constitution provides a temporary line of succession for the president but not the vice president, he said.

His attorney kept the letter. For years, he said, then-President George W. Bush was the only other person who knew about the letter's existence.

Cheney also recalled a period when his health was at his worst and he was sedated for several weeks. He said he dreamed he spent a "very pleasant interval" in a village north of Rome, eating good food and drinking fine wine.

He said Liz Cheney asked him when he awoke if any of his family were there. He said no.

"That was not the right answer," Dick Cheney said. "They'd been through a very, very difficult set of circumstances for several weeks. A near-death experience for me. And great worrying and concern on their part.

"And I'm having a high old time in Italy."