Nine weeks after he received a thumb-sized pump to boost his weakened heart, Woodrow Snelson left the University of Maryland Medical Center yesterday and celebrated some of the routine pleasures of life.

"The cool, crisp air really felt good," said Snelson, 63, of Burtonsville, who stopped at a local restaurant on his drive home. "I feel absolutely fantastic."

Snelson, who could barely get out of a chair before surgery, said he can now walk around his house and yard and even climb a flight of stairs.

Though there are many types of heart pumps in use throughout the United States, Snelson's is smaller and simpler than most. Implanted within the left ventricle, the main pumping chamber, it is simply a fan that helps move blood to the aorta.

It is connected by a single wire to an outside battery pack that Snelson wears on his hip. Dr. Stephen S. Gottlieb, a cardiologist at the medical center, said he hopes the pump's simplicity will make patients less prone to risks such as blood clots.

In September, Snelson became the 30th patient nationwide and the first on the East Coast to receive the experimental pump, which was designed by Dr. Robert Jarvik, a New York surgeon who is best known for inventing the artificial heart.

The pump, which was implanted by Dr. Bartley P. Griffith during an eight-hour procedure, is intended as a bridge to an eventual transplant. Yesterday, Snelson said he plans to gain some weight and strength so he will be in better condition for a transplant.

"It's been fascinating to watch him," said Gottlieb. "He has gradually and steadily improved his level of activity. In addition, his own heart muscle has improved."