But in the meantime, Mr. Cheney has begun resuming his old activities. Besides the Cino fund-raiser, he attended a round of holiday parties in Washington — leaving whispers in his trail about his weight loss. “For all of the caricatures of him, he never lets it get under his skin,” said Ms. Matalin, a close friend.

Mr. Cheney, who spent the holidays at his ranch in Wyoming, recently had a class of West Point cadets over to his house in McLean, Va., to talk about his experiences working for four of the last five Republican presidents and what it was like to work at the White House. In Wyoming, he has been spotted in local grocery stores, stocking up to make chili and spaghetti sauce, “as well as walking me through how to cook Christmas dinner,” his daughter Liz Cheney said in an e-mail.

But most of all, Ms. Cheney said, her father has been working on his book, which is scheduled to come out this fall. “He still prefers to write in longhand on yellow legal pads despite my efforts to introduce a laptop into his process,” Ms. Cheney said.

By supplementing the amount of blood pumped through the body, Mr. Cheney’s pump allows him to do many things he would do with a working heart. Such patients can bicycle, golf, play tennis, drive, shop and generally do what they did before they developed severe heart failure. They need to take an anticoagulant, like warfarin (sold under the brand name Coumadin), and have blood tests to monitor the amount.

Mr. Cheney’s pump was placed near his heart. With most patients, a power line emerges about waist level and connects to a controller, a minicomputer that plugs into a pair of one-and-a-half-pound, 12-volt batteries. Patients wear a black mesh vest over their clothing that holds the controller and batteries.

Mr. Cheney’s friends and family say he is making plans to get out in 2011 and give more speeches. On Jan. 20, he is to fly to Texas for the 20th anniversary of the Persian Gulf war with the first President Bush, the emir of Kuwait and a host of alumni of that administration, including Brent Scowcroft, the former national security adviser, and Colin L. Powell, who was chairman of the Joint Chiefs of Staff at the time, when Mr. Cheney was defense secretary.