A Lifesaving Implant

A Lifesaving Implant

An abdominal aortic aneurysm is a balloon-like bulge in the aorta often linked to hardening of the arteries. It is a dangerous condition. If it bursts, it’s usually deadly. But tracking aneurysms may soon be easier. In the past, a “stent” was placed in the artery to keep blood from accumulating in the aneurysm. The size of the bulge was monitored through lengthy and expensive CT scans every six months.

Now researchers, led by Takao Ohki of Montefiore Medical Center in New York, are testing the “EndoSensor,” a device that allows doctors to measure pressure, which is a key factor in preventing ruptures. It’s implanted near the stent in a minimally invasive procedure. To monitor the aneurysm, a doctor waves an electronic wand over the abdomen.

The wand picks up radio signals from the sensor, which are translated into a pressure reading. Since there’s no radiation, the aneurysm can be monitored more often, which allows doctors can detect changes sooner. If pressure is high, the stent may need to be replaced. The “EndoSensor” could be available later this year. Live long and prosper.

CardioMEMS, a member of Georgia Tech’s Advanced Technology Development Center (ATDC), is pioneering a new breed of testing devices to monitor heart patients. Combining wireless communications technology with microelectromechanical systems (MEMS) fabrication, CardioMEMS’ products can provide doctors with more information while making testing less invasive for patients.
Deborah McGee of CardioMEMS examines an EndoSensor in the company's clean room facility in the ATDC Biosciences Center located at Georgia Tech's Environmental Science and Technology Building. The sensor is implanted to measure pressure in an aneurism being treated by a stent graft.

In June, the U.S. Food & Drug Administration (FDA) approved CardioMEMS’ investigational device exemption (IDE), which enabled the company to begin clinical trials in the United States for its EndoSensor™.

The EndoSensor measures blood pressure in people who have an abdominal aortic aneurysm, a weakening in the lower aorta. This condition ranks as the 13th leading cause of death in the United States. If the aneurysm ruptures, a person can bleed to death within minutes.
Doctors can treat the aneurysm with a stent graft, a slender fabric tube placed inside the bulging artery to brace it and relieve pressure by creating a channel for blood flow. Still, the stent can fail, resulting in leakage of blood into the aneurysm, which can cause the aneurysm to burst. For this reason, lifetime monitoring is required.

Safer, easier testing Up to now, doctors have relied on CT scans for testing, but CT scans have limitations. “One problem is that CT scans only show the size of the aneurysm,” explains David Stern, CardioMEMS’ chief executive. “Yet pressure, which is what our device monitors, is the most important measurement.”

CardioMEMS engineer Michael Fonseca uses a laser to separate pressure sensors in the company's clean room facility in the ATDC Biosciences Center located at Georgia Tech's Environmental Science and Technology Building.

CT scans are also time-consuming and expensive, Stern adds. And for patients who require lifetime monitoring, there’s a safety issue due to repeated exposure to radiation and contrast dyes that are toxic to kidneys.

CardioMEMS’ biocompatible sensor, which is implanted along with the stent, monitors the stent more effectively than CT scans. It’s also cheaper and more convenient. During checkups, patients don’t even need to remove their clothes. The physician merely waves an electronic wand in front of the patient’s chest. Radio-frequency waves activate the EndoSensor, which takes pressure measurements and then relays the information to an external receiver and monitor.

CardioMEMS conducted its first U.S. implants at the Cleveland Clinic in July. By the end of December, approximately 100 patients in four countries (the United States, Canada, Argentina and Brazil) had received sensors. CardioMEMS will submit resulting trial data to the FDA early this year, and Stern hopes to receive permission to start selling the EndoSensor by mid-2005.
Deborah McGee of CardioMEMS prepares a batch of the company's pressure sensors for a final cleaning step.

“Our trials show the EndoSensor is safe and producing good data,” reports Stern. “Doctors are enthusiastic because the sensor is very easy to use even though it’s complex technology.”

Enjoy your life!!