Changes in Coronary Flow Reserve following Stent Implantation in the Swine Descending Thoracic Aorta

Purpose: To evaluate coronary flow reserve (CFR) changes following stent implantation in the descending thoracic aorta (DTA) of a porcine model. Methods: Six pigs (3 males; 40 to 44 kg) were anesthetized and kept on mechanical ventilation. A 6-F guiding right Judkins catheter was advanced under fluoroscopy to the right coronary artery, and a pressure wire with a temperature sensor was placed within the vessel lumen at a distance of 4 cm from the ostium. CFR was estimated by the thermodilution method before and after maximal coronary vasodilation with 20 mg of intracoronary papaverine. Aortography was also performed to measure aortic diameter. Subsequently, a self-expanding vascular stent was deployed into the DTA just below the left subclavian artery (LSA), and CFR was measured again. All animals were maintained for 3 weeks; at the end of this period, a further CFR was calculated using the same procedure. Results: The mean aortic diameter below the LSA was 12.15±0.15 mm. Following stent deployment, the mean aortic diameter measured at the stented segment was 12.58±0.11 (p=0.001 versus baseline). The mean CFR value was 4.7062.00 before stent implantation, 2.6860.86 immediately after, and 4.0561.15 at 3 weeks after stenting. Accordingly, CFR values were significantly depressed immediately after stent placement compared with baseline (p=0.027). However, CFR values obtained 3 weeks following stent deployment were similar to the initial values (p=0.59). Conclusion: Stent deployment in the normal swine DTA produces a significant immediate decrease in CFR, which is attenuated 3 weeks later. The clinical impact of CFR changes following DTA endografting remain to be elucidated.