Implantable accelerometer system for the determination of blood pressure using reflected wave transit time

• Arterial movement tracked by implantable accelerometer.
• Blood pressure determination with high accuracy.
• Implantable system for long-term monitoring.

A sensor system for continuous monitoring of blood pressure using an acceleration sensor implanted on an artery using minimally invasive techniques is described. The sensor relies on measurement of the reflected wave transit time (RWTT). This implantable system is fabricated on a flexible substrate using 2 mm × 2 mm acceleration sensors and a telemetric unit for transmission of the data. In vivo experiments show that the RWTT can be reliably determined from arterial acceleration signals. RWTT and systolic blood pressure are shown to be strongly coupled, with a correlation coefficient of 0.96, as determined from measurement of 1800 pulses with a mean deviation of the blood pressure of only 4.3%. The system was implanted in an animal and was able to telemetrically transmit acceleration plethysmographs with high quality out of the awake animal.