6f introducer

For OCT imaging, an ILUMIEN Optis system (St. Jude Medical) with a swept source at 1305 AE 55 nm at 22.6 mW was used, which enabled an A-scan depth of 7 mm in air and 4.83 mm in the used contrast agent. Therefore, the imaging depth of OCT in tissue should be 7 mm∕n_tissue, n: 1.33 to 1.55. The system had an A-scan repetition rate of 90 kHz that allows a frame rate of 180 images per second. As catheter, the corresponding C7 Dragonfly (St. Jude Medical) was used. The catheter was inserted through a 6F introducer (B. Braun, Melsungen, Germany) attached to a guidewire (Terumo, Tokyo, Japan), which was advanced into the descending aorta. Before the OCT imaging, the contrast agent was manually injected into the side port of the imaging catheter. The software of the ILUMEN system recognized the purging with the contrast agent and automatically started a pullback sequence with the predetermined length of 40 mm. All data were saved to the ILUMEN system and reviewed with the help of a cardiologist.

Rabbits weighing 3.25 to 3.58 kg were anesthetized by intravenous injections of ketamine 2 to 8 mg∕kg (Ketamin "Gräub" 10%, Albrecht, Aulendorf; Germany) and xylazine 0.5 to 1 mg∕kg (Rompun Trockensubstanz, Bayer, Leverkusen, Germany). The maintenance of the anesthesia was realized through intravenous administration of ketamine 4 mg and xylazine 1 mg via a marginal ear vein. Via cervical incision, the right common carotid artery was prepared and the distal end was ligated. After small arteriotomy, a 6F introducer (B. Braun, Melsungen, Germany) was inserted, followed by the insertion of a guidewire (Terumo, Tokyo, Japan), which was advanced into the descending aorta. Via a 6F catheter (Cordis, Langenfeld, Germany) contrast medium (Visipaque, GE Healthcare Buchler, München, Germany) was injected to obtain an angiogram of the complete aorta. Subsequently, the Dragonfly catheter was introduced and several C-scans over the whole scan range were done. In the next step, the catheter was withdrawn, the Raman-probe advanced until the aortic bifurcation and was slowly removed to generate Raman-data on defined aortic places (Fig. 2). At an acquisition time of 1 to 10 s per point spectrum, the total experiment time per animal was not longer than 5 min for the Raman data collection.