The soft artificial heart resembles the human heart in appearance and function. Image credit: Zurich HeartThe soft artificial heart resembles the human heart in appearance and function. Image credit: Zurich Heart

There are more than 25 million people on Earth that suffer from heart failure who are waiting for a donor heart. To satisfy all is a gargantuan task because there is always a shortage. While these patients wait for a donor, artificial blood pumps keep them alive. It has been an ongoing research effort by engineers and doctors to create an artificial heart that mimics the functions of the human heart.

On July 13, 2017, a group of researchers from the Swiss Federal Institute of Technology in Zurich (ETH Zurich) announced the development of a soft silicone heart that beats and functions almost like a human heart. It also looks like a human heart.

The silicone heart was developed by doctoral student Nicholas Cohrs working in the group Zurich Heart led by Wendelin Stark, professor of Functional Materials Engineering. The project started with the idea that nature should be used as a model to develop the heart. Blood pumps have many disadvantages: (a) they do not produce a physiological pulse, which produces uncomfortable feelings in the patient; (b) their mechanical parts can stop functioning; (c) they are bulky. "Therefore, our goal is to develop an artificial heart that is roughly the same size as the patient's heart and that imitates the human heart as closely as possible in form and function," says Cohrs.

The silicone heart was created using a 3-D printer. It weighs 390 grams and its volume is similar to the real organ. "It is a silicone monoblock with complex inner structure," explains Cohrs. The Zurich heart has a left and right ventricle like the human heart. The two ventricles are not separated by a chamber that is used to produce the contraction of the heart by means of pressurized air.

The researchers proved that this soft artificial heart works and functions similarly to the human heart. There is a problem, however: the “muscle” contractions only last for about 3,000 beats, or less than one hour. The reason: the silicone, the material used to build the heart, does not withstand the strain for too long. "This was simply a feasibility test. Our goal was not to present a heart ready for implantation, but to think about a new direction for the development of artificial hearts," explains Cohrs. “Of course, the tensile strength of the material and the performance would have to be enhanced significantly,” he adds.

Even with this big problem, the Zurich heart offers big hope for millions of people around the world. The researchers have proved that an artificial heart with the same softness, size and fundamental functions of a real heart is achievable. "As a mechanical engineer, I would never have thought that I would ever hold a soft heart in my hands. I'm now so fascinated by this research that I would very much like to continue working on the development of artificial hearts," says Anastasios Petrou, a doctoral student of the Product Development Group Zurich.

The results of the study were published in the journal Artificial Organs and an abstract can be found here: