Knitting Hearts

Dr. Franz Freudenthal is a cardiologist and an inventor.
By Kio Herrera
As seen on
Time for Kids
A doctor in colorful scrubs smiles with a young patient on a hospital bed
Dr. Alexandra Heath, left, with a patient at a heart center in La Paz, Bolivia

Bolivia is a South American country known for the majestic Andes mountains. It is also one of the poorest countries on the continent. Bolivia is not considered a leader in medical innovation. But a Bolivian doctor is helping to change that.

Dr. Franz Freudenthal is a cardiologist, or heart doctor. He is also an inventor. His creations help him in his work as a doctor. One is called the Nit-Occlud, and it’s used to treat atrial septal defect (ASD). The condition is often called “hole in the heart.” Freudenthal’s device can fix it without major surgery.

The Nit-Occlud is made by knitting a single metal string into a mesh. The mesh is then implanted into the heart through a narrow tube inserted into a blood vessel. Once inside the heart, the device expands and blocks the hole.

At High Risk

Doctors don’t always know what causes children to be born with ASD and other heart defects. But high altitudes could play a role.

La Paz, Bolivia, sits almost 12,000 feet above sea level. Freudenthal says children born there are more likely to have a heart defect. “The baby does not grow” properly, Freudenthal told TFK. ASD can make it hard for a child to breathe.

Before it is implanted, the Nit-Occlud looks like a tiny top hat. Once inside the body, it expands into a circular shape.

Freudenthal’s Nit-Occlud implant is giving hope to young patients and their parents. “Now there is a solution,” he says. “And it is such a simple solution.”

The Perfect Design

Freudenthal’s device is a modern miracle. But he says the real miracle is how medicine and traditional culture are working together to save lives.

The Aymara people have lived in Bolivia for thousands of years. Their folktales tell how their god Tunupa taught them how to knit and weave. Freudenthal grew up in Bolivia. As a child, he was captivated by weaving and knitting done by Aymara women. The finely detailed work would one day play a big part in the creation of the Nit-Occlud.

How so? Freudenthal wanted to create a device that was easy to implant. He came up with a design that relied on knitting. The device would be so small that it would have to be made by hand. He thought of the work of the Aymara women. He needed help from their expert fingers. So he recruited some of the best knitters in the world to make the Nit-Occlud a reality.

A team of Aymara women now knits the devices by hand in a pediatric clinic founded by Freudenthal and his wife, Dr. Alexandra Heath.

“There is only so much I can do after I implant the device—it must work on its own,” he said. “In some regard, these women are as much a part of the surgery as I am.”

This article was originally published in TIME for Kids on March 5, 2018.