Wearable Ultrasound Patch Images the Heart In Real Time

A wearable ultrasound imager for the heart that is roughly the size of a postage stamp, can be worn for up to 24 hours, and works even during exercise may one day help doctors spot cardiac problems that current medical technology might miss, a new study finds. IEEE Spectrum reports: Now scientists have developed a wearable ultrasound device that can enable safe, continuous, real-time, long-term, and highly detailed imaging of the heart. They detailed their findings online on January 25 in the journal Nature. "Potential applications include continuously monitoring the heart in daily life, during exercise, during surgery, and much more," says study coauthor Ray Wu, a nanoengineer at UC San Diego. "This will open up the possibility to detect previously undetectable symptoms of disease, identify symptoms in their very early stages, and greatly improve patient outcomes."

The new device is a patch 1.9 centimeters long by 2.2 cm wide and only 0.9 millimeters thick. It uses an array of piezoelectric transducers to send and receive ultrasound waves in order to generate a constant stream of images of the structure and function of the heart. The researchers were able to get such images even during exercise on a stationary bike. No skin irritation or allergy was seen after 24 hours of continuous wear. "The most exciting result is that our patch performs well when an individual is moving," Hu says. "Our patch allows us to evaluate heart performance throughout exercise, providing valuable information about the heart when it is under high stress." The new patch is about as flexible as human skin. It can also stretch up to 110 percent of its size, which means it can survive far more strain than typically experienced on human skin. These features help it stick onto the body, something not possible with the rigid equipment often used for cardiac imaging.

In the new study, the researchers focused on imaging the left ventricle, the largest of the heart's four chambers "and strongly considered to be the most important in terms of cardiovascular health, as it is responsible for pumping oxygenated blood to the entire body," Wu says. Cardiac imaging generally focuses on the left ventricle, but the new device can image all of the heart's four chambers simultaneously, "so it may be possible for future research to focus on other or multiple chambers," he adds. In addition, "the imager can be applied to image various other organs, such as the stomach, kidney, or liver." Traditional cardiac ultrasound imaging constantly rotates an ultrasound probe to analyze the heart in multiple dimensions. To eliminate the need for this rotation, the array of ultrasound sensors and emitters in the new device is shaped like a cross so that ultrasonic waves can travel at right angles to each other. The scientists developed a custom deep-learning AI model that can analyze the data from the patch and automatically and continuously estimate vital details, such as the percentage of blood pumped out of the left ventricle with each beat, and the volume of blood the heart pumps out with each beat and every minute. The root of most heart problems is the heart not pumping enough blood, issues that often manifest only when the body is moving, the researchers note.