GARDINER – The Rev. Jacob Fles and his daughter Broghann are about to depart on a long journey together.

At 7 a.m. Monday, they will be on operating tables at the Lahey Clinic, a teaching hospital in Burlington, Mass.

The 18-year-old Gardiner Area High School senior will donate part of her liver to her father, pastor of the Christ Church Episcopal parish.

The procedure, known as living-donor liver transplantation, enables a patient to get a transplant immediately, instead of waiting for a donor to die.

Broghann will give up 70 percent of her liver, she said, which is expected to grow back completely in about two months.

Jack Fles, 56, has hepatitis C and pulmonary hypertension, a secondary condition caused by liver disease in some patients. His heart became enlarged because it had difficulty moving blood from his liver to his lungs.

To prepare for the surgery, Fles — known as “Father Jack” among parishioners and nonparishioners in Gardiner — has taken medication for 16 months to relax his heart and reduce its size, by opening veins and arteries to allow more blood to pass through it.

“I’ve been planning to do this since I was 16 years old,” Broghann Fles said. “Doctors thought it would be better to wait until I was 18, mostly for liability issues because I was a minor.

“It’s been pretty stressful waiting all this time, but I have a lot of friends and we have a really good family system here,” she said.

Jack Fles said the waiting has been stressful on his family and parishioners.

He said he is excited, but nervous about the surgery and his daughter’s part.

“We’ve discussed our fears together — the possibility that somebody, either one of us, could die,” he said. “We’re both trusting that that’s not going to happen.”

With the surgery on hold for the past two years, Jack said, he has been forced to slow down and think about how he uses his time.

“I have been able to spend more time with my family, which has been tremendously rewarding,” he said. “I’ve found out things about the kids and (wife) Becky that I was not clearly able to see beforehand. I am extremely grateful to my daughter for her generosity and unwavering determination. And Becky, for her persistence in working with doctors and insurance companies while caring for the family and serving as school board chairman.”

He said he’s also grateful for his 22-year-old daughter Keegan who took a year off from college to care for her 9-year-old brother Jacob, while the family went back and forth to hospitals.

Becky Fles said doctors were going to let Broghann be a live donor at 16, but decided against it after losing a 56-year-old donor on the operating table.

Four living liver donors have died in the United States since 1999, according to the United Network for Organ Sharing.

“After that, they shut us down until her birthday, on August 30,” Becky said.

She said there is a tremendous need for liver donors in the Northeast. A donor cannot be a heavy drinker or a drug user, and the liver must be undamaged.

“I just wish people understood what it means to be a live donor,” she said. “If people could only be as courageous as my daughter and give a portion of their liver, which always grows back.”

About 38 percent of liver donors have some kind of complication, according to the Adult-to-Adult Living Donor Liver Transplantation Cohort Study, a project to disseminate information about living-donor liver transplants.

Broghann exceeded standards as a donor, and doctors were surprised by her willingness and eagerness, said Becky Fles, who believes that Broghann may be the youngest living donor in the country.

She will be hospitalized five to seven days, while her father will spend perhaps 12 to 15 days in the hospital.

They will recover at home; Broghann won’t return to school for another two months. She will be tutored by friends and teachers, she said.

“Not many people know that the liver is the only organ that can regenerate,” she said. “The outside portion will grow back in about three weeks, and the rest of it, inside, will take over two months.

“It’s a blood organ, it’s filled with blood, so bleeding is an issue. That’s why I can’t go back to school,” she said.

“Everyone asks the question why I’m doing this,” she said. “It’s a pretty obvious reason. He’s my dad and I love him.”