title: A Novel Technique for Endovascular Detection and Removal of Radiographic Contrast during Angiography.
abstract: OBJECTIVE
  This study aims at in-vitro validation of the principles of endovascular detection of contrast medium and assessing the feasibility of in-vivo detection and removal of contrast during angiography.
  
  
  BACKGROUND
  Contrast-induced nephropathy is a growing concern in current percutaneous interventions with increasing lesion complexity and patient comorbidity. To address this clinical problem, a novel method of endovascular detection and automatic removal of contrast has been developed, and is comprised of a catheter-based system with a reflectance-type optical sensor.
  
  
  METHODS
  Blood samples were obtained from ovine subjects to characterize the optical response of blood by measuring the reflectance spectrum at varying levels of hematocrit diluted by a contrast agent. The results from the in-vitro test were implemented into an in-vivo system. An aspiration catheter equipped with a fiberoptic sensor was inserted into the coronary sinus (CS) of 5 canines. Contrast was administered through the coronary artery and reflectance signals were recorded at the CS. The removal rate was analyzed through 20 specimen collections.
  
  
  RESULTS
  A proportional relationship was found between hematocrit and reflectance intensity in in-vitro test. Upon in-vivo detection of contrast, the sensor signal showed a 79.5 +/- 9.9% (n = 33) drop from the pre-injection baseline. This was highly reproducible and beyond the noise level of baseline, (2.5 +/- 0.9%), enabling automatic activation of the aspiration system. The signal duration was 12.2 +/- 3.7 seconds. The removal rate of contrast was 59.3 +/- 11%.
  
  
  CONCLUSIONS
  The present study validated the principles of endovascular contrast detection and demonstrated the feasibility of an in-vivo, catheter-based removal of contrast using reflectance technology.
authors: Center for Cardiovascular Technology, Stanford University Medical Center, CA 94305, USA.
authors: Hyeonsoo
authors: H
authors: Chang
authors: Ali H M
authors: AH
authors: Hassan
authors: Young L
authors: YL
authors: Kim
authors: Lester J
authors: LJ
authors: Lloyd
authors: Bon-Kwon
authors: BK
authors: Koo
authors: Junya
authors: J
authors: Ako
authors: Yasuhiro
authors: Y
authors: Honda
authors: Charles J
authors: CJ
authors: Davidson
authors: Peter J
authors: PJ
authors: Fitzgerald
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D003287:Contrast Media / Q000009:adverse effects*; D017023:Coronary Angiography / Q000009:adverse effects / Q000379:methods*; D054326:Coronary Sinus; D004285:Dogs; D005240:Feasibility Studies; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D007674:Kidney Diseases / Q000139:chemically induced / Q000517:prevention & control*
chemical_list: D003287:Contrast Media