MIAMI BEACH, FL - CT scans following endovascular repair of the aorta could be a thing of the past if tiny sensors currently in development prove successful, according to a presentation at the International Symposium on Endovascular Therapy (ISET) this week.
Endovascular repair is gaining favor with physicians and patients because of a shorter recuperation time (counted in days compared with months for traditional open surgery), as well as reduced morbidity and less time off work.
But the endovascular procedure can also lead to slippage and leakage of blood into the aneurysm sac. If pressure in the sac increases, rupture can occur, which can be fatal.
"Right now we monitor the sac with CT," said co-author Dr. Takao Ohki, chief of the division of vascular and endovascular surgery at Montefiore Medical Center in New York City. At ISET, Ohki discussed his data from animal studies.
However, while CT scans measure the size of the sac, the modality does not offer information on the amount of pressure in the sac, Ohki explained, and it is the pressure that is critical. CT follow-up also carries a substantial price tag; patients generally return for four CT examinations in the first year and then every six months to a year afterwards, Ohki said.
An alternative to traditional imaging might be a wireless microchip technology called micro-electro mechanical systems (MEMS), which can gauge pressure inside of the repaired sac, making monitoring more frequent and convenient, as well as less expensive, he said.
Ohki is the principal investigator in a clinical trial, expected to begin within a month, that will evaluate the use of a vitamin pill-sized device from Atlanta-based CardioMEMS. The device would be implanted in the sac with a catheter at the time of endovascular repair. Blood pressure readings inside the aneurysm could be taken at any time, in doctors offices and by patients at home.
In another presentation, investigators from Mt. Sinai Medical Center in New York City shared their experience with an ultrasound-based device for monitoring implants. The ImPressure transducer (Remon Medical Technologies, Caesaria Industrial Park, Israel) relays pressure measurements to a handheld probe, potentially spotting abdominal aortic aneurysm. The transducer is fixed to the exterior of an endovascular stent-graft, loaded within a sheath, and deployed.
"Intrasac pressures were measured directly with an intravascular catheter and by the remote sensor at the time of stent graft deployment," said Dr. Robert Lookstein, associate professor of radiology at Mt. Sinai.
Fourteen patients made up the study population. Follow-up sac pressures were measured by remote sensor and correlated with systemic arterial pressure at every follow-up visit. Lookstein reported "excellent" concordance between catheter-derived and transducer-derived intrasac pressure at the time of abdominal aortic aneurysm repair.
"This is the first report of a permanently implantable pressure transducer in humans for the long-term monitoring of endovascular abdominal aortic aneurysm repair," Lookstein said. "Additional clinical follow-up will be necessary to determine if aneurysm sac pressure monitoring can replace CT scan in the long-term surveillance of patients after endovascular aneurysm repair."
"These are important technological developments that are going to affect the future of these endovascular procedures ... if we can show it is effective and it is reliable," commented Dr. Barry Katzen, director of the Miami Cardiac and Vascular Institute. These devices will give physicians "information on demand at low cost that will also provide for patient convenience," he added.
By Edward SusmanAuntMinnie.com contributing writer
January 30, 2004
Related Reading
Cook to begin testing endovascular TAA graft, December 11, 2003
Saline flush boosts contrast enhancement in abdominal CT, November 6, 2003
Doppler measurements of hemodynamic factors aid in trauma case management, October 16, 2003
Copyright © 2004 AuntMinnie.com
