Time Dependent Correlation Between Sac Behaviour and Re-intervention after Endovascular Aneurysm Repair.

OBJECTIVE: This study aimed to investigate the correlation between aneurysm sac behaviour and time to re-intervention after endovascular aneurysm repair (EVAR). METHODS: A retrospective observational cohort study of patients who underwent EVAR at a single centre between January 2008 and November 2011 and who were followed up for a mean of 6.6 ± 2.9 years was conducted. Based on sac appearances on pre-operative imaging and imaging at the end of follow up, patients were stratified into two groups: (1) sac regression; and (2) no sac regression. The no sac regression group was further subdivided into stable sac group and sac expansion group. Sac regression and expansion throughout follow up were defined as a decrease or increase in the abdominal aortic aneurysm sac diameter of ≥ 5 mm compared with the pre-operative size. A Cox proportional hazards model using multiple failure per subject data was used to identify sac behaviour as a predictor of re-intervention free time. RESULTS: Patients with sac regression had a higher probability of freedom from re-intervention compared with those with a stable or expanding aneurysm sac (94%, 57%, and 16% at 12 years, respectively; log rank, p < .001). Mean time to re-intervention was 11.3 years for the sac regression group, 8.8 years for the stable sac group, and 5.0 years for the sac expansion group (p < .001). In the stable sac group, the risk of re-intervention increased sharply six years after EVAR, whereas in the sac expansion group a sharp rise in re-intervention was noted 3.5 years after EVAR, reaching a plateau after year 6. CONCLUSION: A time dependent correlation between aneurysm sac behaviour and re-intervention was found. Such findings have implications for surveillance strategies.

Spinal cord early ischemic preconditioning activates the stabilized fraction of ß-catenin after thoracoabdominal aortic occlusion in pigs.

BACKGROUND: Paraplegia after thoracoabdominal aortic surgery is a devastating complication attributed to motor neurons loss and dysfunction, due to spinal cord ischemia. ß-Catenin is a protein that has been associated with cell survival and healing and many studies have correlated this protein with late ischemic preconditioning (IPC). Herein we investigate the potential contribution of ß-catenin in an early IPC animal model, and its relationship with heat shock protein 70 (Hsp70), suggesting a possible role of this protein as a first window of protection. METHODS: A total of 42 pigs were used in an experimental thoracoabdominal aortic occlusion model. Twelve animals were used for neurologic evaluation and were randomly assigned to 2 groups (A and B). The remaining 30 animals were used in experiments for biologic measurements and innunohistochemical studies, and were randomly assigned to 5 groups (1-5). Western blotting analysis and immunoprecipitations were performed to study the levels of ß-catenin and its binding relationship with Hsp70. The cellular distribution of ß-catenin at various time-points was investigated by immunohistochemical studies. RESULTS: According to neurologic evaluation, the animals in the IPC+ischemia group had significantly better neurologic scores compared with those in the ischemia group, indicating a protective role for IPC. The biologic measurements demonstrated a significant (P=0.03) increase in ß-catenin levels and translocation of the protein in the nucleus at the end of ischemic preconditioning. CONCLUSIONS: Our results suggest a significant role of ß-catenin in early IPC protection of spinal cord after thoracoabdominal occlusion, as IPC seems to trigger the activation of the ß-catenin stabilized fraction and, thus, its survival pathway.