Creative scientists have come up with an ingenious way to bypass damaged heart tissue with new prosthetic technology. Thin, flexible fibers made of carbon nanotubes can bridge damaged heart tissues and deliver the electrical signals needed to keep those hearts beating.
Scientists at Texas Heart Institute (THI) reported in August 2019 that, in laboratory animal experiments, they were able to sew thin, flexible, biocompatible fibers invented at Rice University directly into damaged tissue to restore electrical function to malfunctioning hearts.
Dr. Mehdi Razavi, a cardiologist, and director of Electrophysiology Clinical Research and Innovations at THI co-led the study with Matteo Pasquali, a Rice chemical and biomolecular engineer. Razavi explained their unique problem-solving approach:
“Instead of shocking and defibrillating, we are actually correcting diseased conduction of the largest major pumping chamber of the heart by creating a bridge to bypass and conduct over a scarred area of a damaged heart.”
The medical innovator continued:
“Today, there is no technology that treats the underlying cause of the Number One cause of sudden death, ventricular arrhythmias. 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.”
In 2013, Pasquali’s lab team invented a way to create conductive fibers from carbon nanotubes (CNTs). The first-generation threadlike fibers measured one-fourth the width of a human hair but bundled tens of millions of microscopic nanotubes. The fibers integrate the mechanical properties of suture materials with the conductive properties of metals.
The researchers claimed their experiments demonstrated that stripping the ends of the nontoxic, polymer-coated fibers, to act as electrodes, restored function during month-long trials in large preclinical models and with rodents. Positive results were achieved in cases where the initial cardiac conduction was slowed, severed or blocked.
The carbon nanotube fibers worked with or could substitute for a pacemaker. In all rodent experiments, conduction stopped after the fibers were removed.
Study co-lead author Mark McCauley conducted many of the experiments while a postdoctoral fellow at THI. He shared his excitement for the possible future of his team’s breakthrough achievement:
“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.”
Razavi noted that his group’s approach to fixing a broken heart is mechanical rather than pharmaceutical:
“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 U.S. and many developing countries around the world.”
The American scientists used radiofrequency (RF) ablation (tissue destruction or scarring) to induce epicardial conduction delay in sheep and then surgically inserted a CNT fiber bridge:
“They found that sewing the conductive fibers across the ablation-induced scar significantly improved conduction, to near baseline values.”
Before moving on to human trials, Pasquali said more work needs to be done on figuring out how to sew the fibers into place via a minimally-invasive catheter. The microscopic fibers must be strong and flexible enough to keep up with a heart that never stops beating.
“Flexibility is important because the heart is continuously pulsating and moving, so anything that’s attached to the heart’s surface is going to be deformed and flexed.”
Other questions facing the researchers include:
- How long and wide should the fibers be?
- Precisely how much electricity do they need to transmit
- How would the nanotube fibers perform in the developing hearts of young patients?
According to Razavi, his team’s invention is a viable solution available when effective antiarrhythmic drugs are contraindicated in patients after a heart attack, which happens often:
“What is really needed therapeutically is to increase conduction. Carbon nanotube fibers have the conductive properties of metal but are flexible enough to allow us to navigate and deliver energy to a very specific area of a delicate, damaged heart.”
The CNT fibers are also being studied for possible use in other medical tasks such as wiring an electrical interface with the brain, for use in cochlear implants, and as flexible antennas. The novel technology may also prove helpful in the automotive and aerospace sectors.