Former U.S. Vice President Dick Cheney was recovering on Saturday after undergoing heart-transplant surgery, a once-risky procedure whose survival rates have improved over the years.

The 71-year-old Republican, who wielded unprecedented power as vice president during the George W. Bush administration's war on terrorism, was in the intensive-care unit at Inova Fairfax Hospital in Falls Church, Va.

Cheney -- who has suffered five heart attacks, the first at age 37 -- had been on the cardiac transplant list for more than 20 months before he received the heart from an anonymous donor.

Although the former vice president and his family do not know the identity of the donor, they will be forever grateful for this lifesaving gift, said a representative, Kara Ahern.

According to the National Heart, Lung and Blood Institute, about 88 percent survive the first year after heart transplant surgery and 75 percent survive for five years. The 10-year survival rate is about 56 percent.

Cheney's transplant followed a series of procedures in recent years to extend the use of his heart. Cheney had bypass surgery in 1988 and later had two angioplasties. In 2001, he had a defibrillator implanted in his chest.

He had a heart pump implanted in 2010 to compensate for worsening end stage congestive heart failure. He said after the operation that he was considering whether to seek a full heart transplant.

Surgeons from the facility where Cheney's surgery was done performed the Washington region's first successful heart transplant in 1986, according to the hospital's website.

The world's first human heart transplant was performed by Christiaan Barnard on a man called Louis Washkansky in 1967. Worldwide, about 3,500 heart transplants were performed annually as of 2007.

During Cheney's eight years as vice president from 2001 to 2009, he wielded unprecedented power for a vice president and pushed a go it alone world view that enraged his critics and dogged him long after he left public life.

He was a strong advocate for the 2003 invasion of Iraq and was among the most outspoken of Bush administration officials warning of the danger from Iraq's suspected stockpile of weapons of mass destruction. No such weapons were found.

Prior to becoming vice president, Cheney served as defense secretary in the George H.W. Bush administration and directed the U.S. military operation to expel Iraq from its occupation of Kuwait in the first Gulf War.

He also is a former congressman from Wyoming.

Inova Fairfax created an open heart surgery program in 1977, according to the hospital's website.

(Reporting by Phil Stewart, Tabassum Zakaria, Eric Beech and Marilyn Thompson; editing by Xavier Briand and Todd Eastham)