Miniature implant monitors cardiac pressure
Technology is delivering a array of health monitoring systems that can record a person’s blood pressure or perform an ECG on the go. Now researchers have turned their attention to monitoring cardiac pressure, an indicator of heart problems that can normally only be measured using an invasive procedure known as a coronary angiography.
The research at the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS) centers on the use of very small sensors that can be implanted into a patient’s heart to monitor cardiac pressure.
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During a coronary angiography, a catheter is inserted into the groin and injecting a contrast medium and using an X-ray screen cardiac activity is monitored. What physicians are looking for is increased pressure in the left chamber of the heart, which could indicate potential heart failure. This procedure is usually performed in emergency situations and only offers temporary observation, but the new developments from IMS could offer a longer-term monitoring option.
The IMS heart sensor system involves implanting battery-free miniature sensors, which are 2 x 10 mm in size, into the wall of the patient’s heart with the aid of a catheter. Cardiac pressure readings can then be transmitted at any time to the attending physician. The rod shaped sensors can deliver up to 200 measurements a second.
"This means even the smallest malfunction of the heart will be revealed," says Dr. Gerd vom Bögel, group manager at the IMS. “And particularly in the initial stages of illness, these tend to occur only sporadically.”
Once the sensors are implanted readings can be taken "on demand" – the reader device supplies energy via induction so there's no need for a battery in the sensor itself.
Currently an output of 90 microwatts is enough to take a cardiac reading, which can be then be transmitted across a distance of up to 40 cm. This distance is relatively small and thus the IMS team are currently working on improving the efficiency of the chip which contains both the sensor and radio unit.
IMS will be exhibiting the system at the Electronica Trade Fair in Munich, from November 9 through 12, 2010.