Wrist implant that keeps track of high blood pressure


Written on Wednesday, April 11, 2007 by Gemini

A tiny device, not much bigger than a grain of rice, implanted in the wrist to keep a round-the-clock check on blood pressure could reduce the risk of heart attacks and strokes.

The miniature sensor sits next to an artery in the wrist and constantly measures changes in blood pressure. It is programmed to transmit the findings to a doctor’s computer. Scientists behind the new implant say it has no batteries that need replacing and, once implanted, can stay in place for the rest of the patient’s life. Three volunteers in the US had the sensor fitted inside their wrists last month as part of a trial designed to test its accuracy.

Blood pressure is measured by checking two readings. Systolic is the pressure inside arteries when the heart is forcing blood through them, and diastolic is the pressure when the heart relaxes. But testing blood pressure when a patient visits their doctor is not always accurate. Some patients suffer a syndrome called ‘whitecoat hypertension’, where the stress of seeing a doctor forces their blood pressure up. In others, readings may vary widely throughout the day.

The new ‘chip-in-a-wrist’ could be the solution. Doctors apply a local anaesthetic and insert the device just underneath the skin next to the radial artery.

A tiny pressure sensor in the device monitors changes in the forces being applied by blood as it flows through the artery. It transmits the findings to a handheld receiver, which stores the information so it can be downloaded to a doctor’s computer later.The US firm which developed the implant, Atlanta-based CardioMEMS, said it is a world first.

“We believe this is the first instance of a wireless sensor being used to monitor blood pressure,” said company chairman Dr Jay Yadav.

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