By Diana Brown, Globe Staff, 3/10/2002

His son, Christopher, 15, was born with a heart defect in which his heart vessels were transposed. He has undergone numerous heart surgeries and procedures in an attempt to correct the problem. In August 2000, he had a pacemaker put into his chest to regulate his erratic heartbeat. Now, his father said, "He's doing really well."

A few months after Cusson's daughter, Aimee, 11, was born, she developed encephalitis. The disease damaged her brain, and she struggles with developmental delays and a seizure disorder.

"It's an everyday thing for these kids," he said. "It's definitely hard. It's a daily thing in our family."

But come Monday, April 15, Aimee and Christopher will be standing on the sidelines of the Boston Marathon with their mother, Jean, cheering on Cusson as he runs with the Children's Hospital Kids at Heart Marathon Team.

"It's definitely a family event," he said of the support his family has given him for training.

When Cusson ran in 1999 in celebration of Christopher's 10-year post-cardiac-surgery milestone, he remembers, Aimee wildly cheered him on.

"I'm psyched to do this for both of my kids," he said. "For me, it's a three-month thing to train, but for my kids, it's every day."

He is also running to raise money for Children's Hospital, where his son is a cardiology Patient and his daughter is followed in the neurology department. "I can't even start to repay them for what they've done for us," he said.

To make donations to the Kids at Heart Marathon Team, send checks to Children's Hospital, c/o Michael Cusson, 19 Old Farm Way, Chelmsford, MA 01824.

Diana Brown can be reached at diana30512@aol.com