A Novel Technique for Endovascular Detection and Removal of Radiographic Contrast during Angiography.

OBJECTIVES: 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%. CONCLUSION: 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.