PITTSBURGH -- Cher Ball watched helplessly through a glass window after her 5-month-old son went into cardiac arrest at a hospital in Washington, D.C.

Doctors put Austin Ball on an artificial heart and lung machine, but said he would probably need a heart transplant, the result of an orange-sized tumor he was born with in his heart. He would have to be transferred to another hospital.

A team of experts flew Austin by helicopter to Children's Hospital of Pittsburgh in a delicate trip that helped save his life. The Pittsburgh team is one of only a handful in the country skilled enough to transport the most critically ill babies and the complex heart-lung machines known as ECMO.

"In some ways, they are very stable because all of the function of the heart and lung has been bypassed," said Kate Felmet, the hospital's director of transport and a critical care physician. "The problem is, if there's any malfunction of the machine, the child will die."

It is rare for children in the U.S. to require ECMO, or extracorporeal membrane oxygenation -- just a few hundred infants a year are put on ECMO around the country. And transporting those kids on the bulky devices is even rarer, doctors say.

A handful of hospitals in the country can do such transports, including the University of Michigan, Arkansas Children's Hospital and Wilford Hall Medical Center at Lackland Air Force Base in Texas.

Wilford Hall has done 69 pediatric ECMO transports since its program started in 1986, said Maj. Dr. Melissa Tyree, medical director of the hospital's ECMO and neonatal intensive care unit transport services. Using specially equipped military planes, the team there has traveled as far as Japan for ECMO patients and can transport both military and civilian patients.

Tyree said many hospitals have ECMO units, but few have transplant centers, making transport services very important because these children often need advanced care. ECMO is designed to be used for just a few weeks, most doctors say.

"They're the most ill of patients so they are needing ECMO because they have complete respiratory and pulmonary failure or cardiac failure, or a combination of both," she said.

Austin was the first child on ECMO that the Children's Hospital of Pittsburgh team was able to move by helicopter. It can be tougher to do the transport by airplane because a child has to be moved out of the hospital, into an ambulance, to the hospital, out of the ambulance again, and on and on, said Kent Kelly, Children's director of Perfusion Services.

"By going helicopter, you're on the top of your hospital" and there are fewer transfers and time wasted, Kelly said. "Time can be really critical."

Kelly said one challenge of transporting children and ECMO devices is making sure there is enough space for the complicated machine. The device includes several pumps and a power source, usually a battery pack, that can sometimes be pretty heavy. Often, the machinery is much bigger than the babies themselves, he said.

The key to a successful trip, he said, is preparation.

"You have everything that you possibly think that you could need physically -- the stuff that I need in the (operating room) every day - extra packs with different size tubings, connectors," Kelly said. "There's nothing you can really do to prepare for what you think is going to happen."

On the October flight with Austin, Kelly said, one of the biggest challenges was the weather. The flight was delayed a couple of times because pouring rain forced them to find a helicopter pilot who was certified to fly by instrument.

Patients' families are rarely allowed on medical flights, and especially on ECMO flights where space is at a premium. Cher Ball said she was nervous to let her son go without her, but knew it was the best option.

"I was willing to go anywhere. When it's his life, I was willing to go to the ends of the earth," she said. "They were so calm. … I was scared but I was excited. I knew we were going to a place to get a transplant."

Cher Ball drove the five hours to Pittsburgh after seeing her son off in the helicopter.

At the hospital, Dr. Victor Morrell, chief of the hospital's Division of Cardiothoracic Surgery, decided to try to remove the tumor and then determine whether a transplant was really necessary. The benign tumor was blocking function in the boy's heart.

"It was killing him … slowly," Morrell said.

Morrell cut the tumor away from Austin's chest, but the boy's heart was so stretched out from the large tumor that doctors had to place the boy on a Berlin Heart. The European heart pump, which is only approved for emergency use in the U.S., is made especially for children.

Those awaiting transplants can be placed on ECMO only for a few weeks, but children implanted with the Berlin Heart tend to become stronger and healthier, putting them in a better condition to survive transplantation.

In Austin's case, his heart recovered so well that the Berlin Heart was removed and his heart is functioning on its own. For now, Austin doesn't need a heart transplant, and only time will tell if he ever will.

"He's golden. He has a real future now," Morrell said.

Stroking her son's head and right ear, Cher Ball, 35, calls Austin a miracle. She said the scars on his chest are the only physical signs that anything was ever wrong with him.

"He's redefined normal," said Ball, of White Plains, Md. "He doesn't know that he's sick. He's kicking, and screaming and hollering."

Dressed in a long-sleeve, blue onesie, Austin Ball lies in bed, loudly cooing for his mom's attention and looking at the colorful mobile hovering above his feet. Near that, a sign in puffy, stick-on letters reads "Get Well Soon Austin," a homemade gift from his big sister.

"You have a lot to say," Ball says to him.

Ball, a physical therapist who took a leave from her job to be by her son's side, said she is thinking of relocating to Pittsburgh so she can be close to Children's Hospital. Austin will require some rehabilitation to re-learn how to eat and other basic skills, and his heart will be monitored, she said.

"I know that they care about Austin," Ball said. "This is a safe haven."