A new wireless cardiac “patch” could allow doctors to continuously monitor patients’ hearts and record electrocardiograms (EKGs) while they are on the go. Such highly portable continuous monitors could help doctors treat cardiac patients, and they may soon become crucial tools in diagnosing conditions in otherwise healthy people, say the device’s developers.
Developed by researchers at the Interuniversity Micro-Electronic Centre (IMEC), an independent nanotechnology research institute in Eindhoven, the Netherlands, the flexible stick-on device is a variation of a Holter monitor, a portable EKG tool currently used by cardiologists to help assess and diagnose their patients. But Holter monitors require a number of electrodes to be stuck to the body and connected, via a tangle of wires, to a bulky recording device worn at the hip.
In contrast, the new device just sticks onto the patient’s chest and wirelessly sends electrical signals detected from the heart to a credit-card-like receiver. These signals can be analyzed and used to sound an alarm as an early warning when dangerous heart rhythms, or arrhythmias, are detected, says Bert Gyselinckx, the director of IMEC’s Wireless Autonomous Transducer Solutions program. For example, the device could be used to alert emergency services to problems suffered by elderly cardiac patients who live alone.
The new device consists of a flexible circuit board just 60 millimeters long and 20 millimeters wide that contains all the circuitry to detect and transmit the EKG signal up to 10 meters. The flexible board slips into a Lycra patch with three sticky points of contact that act as the EKG electrodes. Short wires within the pouch connect the contact points to the circuit board via snap-on sockets. “This makes it easier to attach the electrodes,” says Gyselinckx.
The signal is sent to the receiver using an off-the-shelf wireless transmitter, which uses technology similar to Bluetooth but at much lower power, says Gyselinckx. The receiver is a smart card–a pocket-sized card with an integrated circuit embedded in it–that also incorporates a thin battery. “It looks and feels like a credit card,” Gyselinckx says. The card can store the EKG data on an embedded two-gigabyte flash-memory device, or it can be hooked up to a handheld computer or cell phone to relay the data to a clinic.
There is a general trend to make heart-monitoring devices wireless because they are so much easier to use, says Mike Kingsley, director of exercise-physiology laboratories at Swansea University, in Wales.
Already, consumer products are available that monitor the heart and send the signal wirelessly to a watch. But these products only detect heart rate, in terms of beats per minute, says Kingsley. “An EKG gives you a lot more information about the way the electrical current is traveling through the heart,” he says. A cardiologist can use this data to determine the morphology and behavior of the heart, both of which are vital to making a diagnosis.