A research team led by investigators at Beth Israel Deaconess Medical Center (BIDMC) and Seoul National University has developed a new electric mesh device that can be wrapped around the heart to deliver electrical impulses and thereby improve cardiac function in experimental models of heart failure, a major public health concern and leading cause of mortality and disability.
The study, published in the June 22, 2016 issue of Science Translational Medicine, points to a potential new way of improving heart function and treating dangerous arrhythmias by compensating for damaged cardiac muscle and enabling living heart muscle to work more efficiently.
Under normal conditions, the heart pumps blood throughout the body through a series of coordinated contractions maintained by a carefully synchronized electrical conduction system. With the development of heart failure - when weakened heart muscle damages the heart's pumping mechanism -- this electrical conduction system can also be damaged.
"Some patients with heart failure are treated with resynchronization therapy, in which three small electrodes are implanted through a pacemaker to keep the heart contracting coordinately," explained corresponding author Hye Jin Hwang, MD, PhD, a researcher in the Division of Cardiovascular Medicine in BIDMC's CardioVascular Institute. "But pacemakers deliver electrical stimulation only at specific places in the heart and do not provide comprehensive coverage of the entire organ, as the heart's own cardiac electrical conduction system does."
"We knew that an integrated strategic approach that directly suppresses ventricular tachyarrhythmia in addition to improving cardiac function would be a promising strategy for the treatment of heart failure, ventricular arrhythmias, and sudden death," said coauthor Mark E. Josephson, MD, Chairman Emeritus of Cardiovascular Medicine at BIDMC, Distinguished Herman Dana Professor of Medicine at Harvard Medical School, and an international leader in the field of electrophysiology.
Made up of nanowires embedded in a rubber polymer that can conform to the unique three-dimensional anatomy of each individual heart, the new mesh is designed to wrap around and "hug" the heart and thereby deliver electrical impulses to the whole ventricular myocardium, or heart muscle. In developing the novel material for this new device, Hwang collaborated with Seoul National University researchers Taeghwan Hyeon, PhD, a specialist in nanomaterials and Dae-Hyeong Kim, PhD, a specialist in stretchable devices. "We wanted to closely imitate cardiac tissue, which is very elastic, and also imitate its unique functions, which are highly conductive," said Hwang.
Working with multidisciplinary research teams spanning seven institutes in the U.S., China and Republic of Korea, Hwang and her colleagues developed the novel nanomaterial, created an elastic electrical device, tailored the device through 3D printing, conducted pre-assessment of mechanics through computer simulation and conducted functional assessment of the device in an in vivo heart failure model.
In studies of rats, the mesh integrated structurally and electrically with the myocardium following heart attack, acting as a substructure of the heart during cardiac movement and improving cardiac contractile function without disturbing relaxation.
"The big advance here has been finding a way to create a device that more accurately mimics normal physiology," explained Peter J. Zimetbaum, MD, Associate Chief and Director of Clinical Cardiology at BIDMC and Associate Professor of Medicine at Harvard Medical School. "The concept of wrapping the heart is not new, but doing it with this attention to a more physiologic approach makes the device exceptionally smart. This is not just another mechanical assist device. It's an innovative physiologic approach and provides an opportunity to bridge sophisticated engineering and medicine."
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