A beating heart relies on a healthy circuitry of electrical signals to maintain a steady rhythm, and when that system breaks down it can lead to grave consequences. Pacemakers and medications can be enlisted to correct these kinds of irregular heartbeats, but scientists are now reporting a new way forward that involves neither, instead using fine carbon threads as electrical bridges to keep the signals circulating.

The research was led by Dr Mehdi Razavi from the Texas Heart Institute, whose previous work in this area has resulted in wireless pacemakers powered by microwaves and surgical tools for obese patients. This time around, the cardiologist teamed up with researchers from Rice University to tackle the dangerous and potentially fatal consequences of an abnormal heartbeat.

"Today there is no technology that treats the underlying cause of the number one cause of sudden death, ventricular arrhythmias," Razavi said. "These arrhythmias are caused by the disorganized firing of impulses from the heart's lower chambers and are challenging to treat in patients after a heart attack or with scarred heart tissue due to such other conditions as congestive heart failure or dilated cardiomyopathy."

Building on earlier work, the scientists developed very fine carbon fibers with electrical conductivity, each measuring a quarter of the width of a human hair. These non-toxic, polymer-coated threads have tens of millions of microscopic nanotubes embedded inside, while their tips are striped back to serve as electrodes.

The team conducted experiments using these fibers as bridges, sewing them into damaged tissue in the hearts of mice as a way of allowing electrical signals to carry on traveling back and forth. Beforehand, the animals had experienced disruptions to the electrical signals in their hearts, but the fibers proved successful in restoring regular function over month-long testing periods, even without the assistance of a pacemaker. When the fibers were removed, the circuits were disrupted once again.

"Our experiments provided the first scientific support for using a synthetic material-based treatment rather than a drug to treat the leading cause of sudden death in the US and many developing countries around the world," says Razavi.

There's a lot to do before the technology is ready for clinical use. For starters, the scientists would need to figure out a way to safely sew the fibers into the hearts of humans. They would also need to work out the ideal length and thickness, while also make them flexible enough to remain a functional part of a beating heart over long periods of time. But the early signs are promising.

"The reestablishment of cardiac conduction with carbon nanotube fibers has the potential to revolutionize therapy for cardiac electrical disturbances, one of the most common causes of death in the United States," says co-lead author Mark McCauley.

The team's research was published in the journal Circulation: Arrhythmia and Electrophysiology.

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