Heartstrings are not just figures of speech — they are real. They are stretching and contracting in your heart right now.

And a medical device startup company called CardioMech is growing operations in Minnesota to create implantable synthetic heartstrings to treat a complex heart condition called degenerative mitral regurgitation, a widespread heart valve disease that allows blood to flow backward inside the heart.

“We have some work to do. But with the right team, the right partners, the right market and the right technology, we just may achieve our objective to significantly improve the standard of care for people with mitral regurgitation,” said CEO Rick Nehm, a Roseville native and industry veteran who has worked at other cardiac device makers, such as Tendyne and ATS Medical.

The human heart contains four valves that regulate how blood flows through its four chambers. Although the aortic valve near the top of the heart has been the site of cutting-edge technical innovation (and billions in profits) at med-tech companies in the past decade, an increasing amount of engineering scrutiny is focusing deeper in the heart, on the mitral valve, where disease is more prevalent.

CardioMech AS, which is based in Norway and building its team in Minnesota, raised $7.5 million in convertible note funding this year, and plans to conduct a Series A funding round soon for its mitral-valve repair system, which is not yet approved in any country.

Another company, NeoChord in St. Louis Park, has worked on the same problem for much longer, having raised $32 million in an extended Series D funding round in the past year for its minimally invasive mitral-repair system. NeoChord has had a system approved in Europe since 2012, but not in the U.S. California-based Edwards Lifesciences is hoping to launch its similar Harpoon system in Europe before the end of the year, after acquiring the technology in 2017 for $100 million plus milestone payments.

All three companies want to sell systems to implant synthetic chords connecting the mitral valve’s leaflets to the heart’s lower musculature, using thin tools that can be fed into the heart through small incisions, avoiding open-chest surgery.

Meanwhile, a panoply of device companies are racing to create the first minimally invasive mitral valve-replacement system to replace the entire valve, rather than fixing native tissue. Chicago’s Abbott Laboratories is hoping its long-running MitraClip system to repair native mitral leaflets by clipping them together in the middle will see sales acceleration following clinical results earlier this year that led to an expanded U.S. indication for the device.

The mitral valve sits between the left atrium, which receives oxygenated blood from the lungs, and the left ventricle, which is the main pumping chamber that pushes fresh blood out to the body. Unlike the aortic valve, the mitral valve is naturally connected to a web of stretchy, tendon-like tissues known to doctors as the chordae tendineae, which are connected to the strong muscles at the base of the heart known as the papillary muscles.

Normally, these mitral-valve chords — the famous “heartstrings” — help to hold the flaps of the mitral valve closed when the ventricle contracts. It’s a critical role, because if blood can seep backward through the mitral valve during a ventricular contraction, it will flow into the atrium instead of out to the body, depriving downstream organs like the brain of some oxygen.

This is known as mitral regurgitation. Symptoms include an abnormal heart sound heard through a stethoscope, fatigue, and shortness of breath, particularly when active or lying down, according to information from the Cleveland Clinic.

Many if not most mitral-valve problems are not severe, and require no intervention. In cases that do need treatment, traditional tissue-repair surgery can be effective. “They’ll fare very well if the surgery is done in a timely manner,” Nehm said. “But many times it’s not.”

The CardioMech device is designed to treat patients who have severe degenerative mitral regurgitation from two causes — prolapse and flail. Prolapse is a floppy leaflet that protrudes up into the atrium, and flail is when a ruptured chord causes the leaflet to become partly detached. About 3 million people worldwide have conditions potentially treatable with a CardioMech device, and roughly 170,000 new patients are diagnosed and referred to specialists for treatment each year.

Nehm noted that the CardioMech system is designed so that a patient could still receive replacement valves later in life if needed, which could make chordal repair a first-line treatment.

CardioMech plans to hit its “design freeze” milestone by year end, and then work with the U.S. Food and Drug Administration toward getting permission for an Early Feasibility Study of the device, with a goal of launching the device in the U.S. first, Nehm said.