title: First experience in human beings with a permanently implantable intrasac pressure transducer for monitoring endovascular repair of abdominal aortic aneurysms.
abstract: OBJECTIVE
  Endovascular stent graft repair of abdominal aortic aneurysms (AAAs) prevents rupture by excluding the aneurysm sac from systemic arterial pressure. Current surveillance protocols after endovascular aneurysm repair (EVAR) follow secondary markers of sac pressurization, namely, endoleak and sac enlargement. We report the first clinical experience with the use of a permanently implantable, ultrasound-activated remote pressure transducer to measure intrasac pressure after EVAR.
  
  
  METHODS
  Over 7 months, 14 patients underwent EVAR of an infrarenal abdominal aortic aneurysm with implantation of an ultrasound-activated remote pressure transducer fixed to the outside of the stent graft and exposed to the excluded aortic sac. Twelve patients received modular bifurcated stent grafts, and 2 patients received aortouniiliac devices. Intrasac pressures were measured directly with an intravascular catheter and by the remote sensor at stent-graft deployment. Follow-up sac pressures were measured with a remote sensor and correlated with systemic arterial pressure at every follow-up visit. Mean follow-up was 2.6 +/-1.9 months.
  
  
  RESULTS
  Excellent concordance was found between catheter-derived and transducer-derived intrasac pressssure intraoperatively. Pulsatile waveforms were seen in all functioning transducers at each evaluation interval. One implant ceased to function at 2 months of follow-up. In 1 patient a type I endoleak was diagnosed on 1-month computed tomography (CT) scans; 3 type II endoleaks were observed. Those patients with complete exclusion of the aneurysm on CT scans had a significant difference in systemic and sac systolic pressures initially (P <.001) and at 1 month (P <.001). Initial sac diastolic pressures were higher than systemic diastolic pressures (P <.001). The ratio of systemic to sac systolic pressure increased over time in those patients with complete aneurysm exclusion ( P <.001). Four of 6 patients with no endoleak and greater than 1-month follow-up had diminution of sac systolic pressure to 40 mm Hg or less by 3 months.
  
  
  CONCLUSIONS
  This is the first report of a totally implantable chronic pressure transducer to monitor the results of EVAR in human beings. Aneurysm exclusion leads to gradual diminution of sac pressure over several months. Additional clinical follow-up will be necessary to determine whether aneurysm sac pressure monitoring can replace CT in the long-term surveillance of patients after EVAR.
authors.affiliation: Division of Vascular Surgery, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Sharif H
authors.initials: SH
authors.lastname: Ellozy
authors.forename: Alfio
authors.initials: A
authors.lastname: Carroccio
authors.forename: Robert A
authors.initials: RA
authors.lastname: Lookstein
authors.forename: Michael E
authors.initials: ME
authors.lastname: Minor
authors.forename: Claudie M
authors.initials: CM
authors.lastname: Sheahan
authors.forename: Jacob
authors.initials: J
authors.lastname: Juta
authors.forename: Andrew
authors.initials: A
authors.lastname: Cha
authors.forename: Rolando
authors.initials: R
authors.lastname: Valenzuela
authors.forename: Michael D
authors.initials: MD
authors.lastname: Addis
authors.forename: Tikva S
authors.initials: TS
authors.lastname: Jacobs
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Teodorescu
authors.forename: Michael L
authors.initials: ML
authors.lastname: Marin
mesh_terms: D017130:Angioplasty; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology* / Q000601:surgery; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004867:Equipment Design; D005500:Follow-Up Studies; D006801:Humans; D015607:Stents; D014160:Transducers, Pressure; D014463:Ultrasonography