High blood pressure, formally known as hypertension, is a leading cause of heart disease in the United States, impacting nearly half of all adults. Approximately one in 10 of these patients experience drug-resistant hypertension that can be difficult to address, but according to researchers at Penn State, tiny devices that gently shock one of the body's most critical arteries could offer effective treatment.
The team developed a new class of 3D-printed bioelectronics made of soft, stretchy materials, as well as an adhesive component that helps the device painlessly stick to biological tissue. The team reported that their new design, which they call CaroFlex and tested in a rodent model, relieved hypertension while causing much less damage to surrounding tissue. They detailed their work in a paper recently published in Device.
According to corresponding author Tao Zhou, Wormley Family Early Career Assistant Professor of Engineering Science and Mechanics, hypertension can traditionally be treated with different drugs and changes to lifestyle or diet. However, drug-resistant hypertension is a pervasive, often chronic condition that does not respond as well - if at all - to conventional treatments.
"For many patients, even taking a combination of three to five medicines doesn't alleviate their high blood pressure," said Zhou, who is also affiliated with the Center for Neural Engineering, Huck Institutes of the Life Sciences and Materials Research Institute at Penn State. "In these cases, bioelectronic devices that use electrical signals to modulate the body's natural response systems offer a promising form of alternative treatment."
This response system is the baroreceptor reflex, or baroreflex, where the walls of the arteries transporting blood around the body constrict and expand to resolve changes in blood pressure. The action is triggered by specialized nerve endings called baroreceptors, which are found across the body and monitor changes in the stretch of arteries. Many of these receptors are in the carotid sinus, a small area where the carotid artery - a vital pathway that supplies oxygen-rich blood from the lungs to the hands, face and neck - diverges into several branches.
According to Zhou, bioelectronics placed on this sinus can use different frequencies of electricity to stimulate the baroreceptors, safely modulating the reflex and alleviating hypertension. While a few commercially available bioelectronics exist to do just this, they are usually made of rigid metals and plastics that do not integrate well with the body's soft tissues, among other key issues.
"These devices are usually held in place with stitches," Zhou said. "These stitches can cause damage to the devices, and more importantly, the tissues they're integrated with over time, as arteries stretch and shrink to help move blood around the body."
