A flexible spaghetti-like tube, perhaps the width of 15 hairs, slides into a vein or artery and is pushed gently through a maze of blood-filled vessels into the beating heart.

The tiny tools packed into its tip relay reams of mechanical and biochemical data about this crucial organ to the cardiologist at a bank of computers next to the patient.

Cardiac catheterization has been around for decades, exploring the heart’s interior structure and function, measuring pressure in its chambers, sampling oxygen in the blood and injecting dye so that obstructions or abnormalities can be visualized. In the past few years, however, this technology has developed to heal as well as to diagnose—and, more recently still, to do so through the thread-like vessels in the tiny fragile hearts of infants as young as a few hours old.

Heart problems are rarer in children than adults, but about 1 in every 100 babies is born with a cardiac defect,” says Dr. Sagui Gavri, head of Interventional Pediatric Cardiology at the Hadassah–Hebrew University Medical Center in Jerusalem. “In a third of them, it is so minor it will resolve spontaneously without treatment. In another third, a one-time repair solves the problem. But the remainder face a lifetime of repeated invasive treatments.”

Fifteen-year-old Maya (not her real name) is among this last group. She was born a blue baby, her skin and mucous membranes a deep cyan because, with her heart pumping too little blood into her lungs, insufficient oxygen was entering her bloodstream.

“The cause was the most common of cyanotic congenital heart defects,” says Dr. Gavri. “Known as Tetralogy of Fallot, it is a blockage in the valve through which blood travels from the heart’s right ventricle to the lungs. This can be surgically corrected at birth: the passage is opened but, unfortunately, the valve that ensures that the blood flows only outward, from heart to lungs, cannot be saved.”

“The days following Maya’s birth were very hard,” says her mother, who prefers to remain anonymous. “She’s our first child. We sent our tiny baby into open-heart surgery and got her back with a scar running down her whole chest and tubes and wires sticking out all over her body. But she survived the operation, her color was more normal and we could touch her. Each day they took out more of the tubes and wires, and six days after surgery we brought her home.”

Maya recovered quickly and, typically, did well for the next eight years without her ventricular valve. Eventually, however, its lack was felt. “Without the valve that enables the right ventricle to force blood into her lungs, some of it was flowing back into her heart, which was filling with blood and enlarging,” says Dr. Gavri. “Left this way, its function would deteriorate and it would ultimately suffer irreversible damage. Children with this and several other types of congenital heart defect need further open-heart surgery to implant an artificial valve—and more surgeries after that to replace the artificial heart valve as they outgrow it and as it wears out.”

Until now. Maya’s story was typical before she came to Hadassah for her fourth openheart surgery at age 15. “It was four years since the last one, and it was clear it was time,” says her mother. “She was pale and listless and breathless. We all knew the physical and mental traumas that lay ahead. We had been through open-heart surgery three times before and were all dreading it.”

This time, however, things went differently. Instead of opening Maya’s chest, Dr. Gavri suggested using a catheter to implant the new valve, inserting it through a small incision in her foot. The delicate technique had been developed at Great Ormond Street Hospital for Children in London and newly introduced to Israel. Dr. Gavri, who specialized in interventional cardiology at Cincinnati Children’s Hospital Medical Center’s Cardiac Catheter Laboratory under Dr. Russel Hirsch, had been to Milan to train in the procedure. Maya’s operation was Dr. Gavri’s first solo procedure; he had a proctor on hand at Hadassah to assist him.

Dr. Gavri placed Maya’s new heart valve (part of a cow’s jugular vein, with three valve leaflets placed within a wire scaffolding or stent) on the tip of his catheter and threaded it through 40 inches of the teenager’s veins, from her rightfoot up to the right ventricle of her heart. Here, guided by the echocardiographic and fluoroscopic images relayed onto the computer, he maneuvered it into the narrow conduit (inserted during a previous surgery) between her right ventricle and her lungs, positioned it firmly in place and inflated it. The bovine replacement valve immediately got to work, regulating blood-flow in one direction, outward into Maya’s lungs.

“There was no blood loss, and so no need for the blood transfusions that follow open-heart surgery,” Dr. Gavri says. “Instead of a surgical incision in the chest [with the scar tissue from each previous surgery making those that follow more complex], there was a small cut in her foot. Hospitalization was overnight, instead of a prolonged stay in intensive care; she experienced no postoperative pain; and she recovered immediately from the procedure.”

A week after the implant, Maya’s mother called Dr. Gavri. “You have made my life very difficult!” she reproached him. “We went to a big Tel Aviv mall yesterday, and I could not keep up with her. She ran from store to store, choosing things, trying things on. She is a different person from two weeks ago, when she hardly had energy to walk down the street!”

Dr. Gavri’s second such patient, an 18-year-old with Down’s syndrome, needed a valve implanted in a narrow heart conduit to reverse significant reduction in his right ventricular function. His procedure went as smoothly as Maya’s. “Although the valves we implanted will wear out and need replacing as before, it seems they have a potentially longer lifespan—even longer than the Great Ormond team expected,” says Dr. Gavri. “Placed within a double stent, they’re lasting well beyond the anticipated 10 years—which is itself twice as long as the average five years between open-heart surgeries. When they are replaced for the first and possibly second times, it will be with the same minimally invasive catheterization procedure.”

New techniques in which Dr. Gavri has trained and which he has brought to Hadassah can be used not only for pulmonary valve replacement, but also for a dozen other procedures—“everything in interventional pediatric cardiology performed in any major medical center,” he says. Using balloons that inflate to open narrowed or closed heart valves, umbrella-shaped devices to close lesions and coil-shaped springs to plug unnecessary vessels, interventional cardiologists can close holes in the wall that separates the heart’s right side from its left, widen narrowed vessels or stiff valves and close off abnormal blood vessels—all via catheterization.

“We have a four-month waiting list,” says Dr. Gavri. “Unfortunately, it will remain long because we have only four specialized pediatric anesthesiologists working with the six senior physicians in our department. Interventional pediatric cardiology is allocated an anesthesiologist for only one day a week.”

In all, the Hadassah team has performed three such catheterizations—all of them successful—with another two scheduled before the end of 2014. It is a pace that scarcely dents the waiting list.

This is a bottleneck that will have to open, says Dr. Gavri. “Therapeutic catheterization joins conventional surgery, enabling doctors to treat and solve highly complex problems that cannot be treated with one discipline alone.”