Temporal Changes in Intraluminal Thrombus Volume Within Abdominal Aortic Aneurysms: Implications for Planning Endovascular Aneurysm Sealing.

PURPOSE: To explore whether or not there are temporal changes in the abdominal aortic aneurysm (AAA) and intraluminal thrombus (ILT) volumes between planning and implantation of the endovascular aneurysm sealing (EVAS) device and how these changes influence lumen volume. METHODS: A retrospective review was conducted of 51 AAA patients (mean age 76±7.1 years; 36 men) in whom 2 serial preoperative computed tomography angiograms (CTAs) had been performed within 1 to 18 months before fenestrated endovascular repair. The 2 preoperative CTAs were analyzed to identify changes in total sac, ILT, and lumen volumes. RESULTS: Over a median 7.0 months (interquartile range 4, 10), 46 (90%) of 51 AAAs increased in volume between the 2 CTAs. ILT volume increased in 44 aneurysms. In contrast, lumen volume increased in 31 and decreased in 20 AAAs. There was a strong correlation between changes in AAA volume and ILT volume (rs=0.859, p<0.001), which remained significant after adjustment for initial volumes (rs=0.815; p<0.001). There was no correlation between the time interval separating the 2 CTAs and changes in AAA volume (rs=0.115; p=0.421), changes in ILT volume (rs=0.084; p=0.599), or changes in lumen volume (rs=0.060; p=0.676). The AAA growth rate (defined as the change in AAA size/days between CTAs) showed a weak correlation with ILT volume (rs=0.272, p=0.054), which disappeared after adjustment for initial AAA size (rs=-0.002, p=0.991). Between the 2 CTAs, 12 aneurysms crossed the new <1.4 Nellix maximum aorta/lumen diameter ratio. CONCLUSION: As AAAs grow, the increase in aortic volume is largely occupied by additional ILT formation, with minimal change in lumen volume. These changes may alter the suitability of the aneurysm for the Nellix device and could have implications for EVAS planning and device deployment.

Changes in Aortic Volumes Following Endovascular Sealing of Abdominal Aortic Aneurysms With the Nellix Endoprosthesis.

PURPOSE: To investigate the effects on aortic volumes of endovascular aneurysm sealing (EVAS) with the Nellix device. METHODS: Twenty-five consecutive patients (mean age 78±7 years; 17 men) with abdominal aortic aneurysms containing thrombus were treated with EVAS. Their pre- and post-EVAS computed tomography (CT) scans were reviewed to document volume changes in the entire aneurysmal aorta, the lumen, and the intraluminal thrombus. The changes are reported as the mean and 95% confidence interval (CI). RESULTS: Total aortic volume was greater on postoperative scans by a mean 17 mL (95% CI 10.0 to 23.5, p<0.001). The volume occupied by the endobags was greater than the preoperative lumen volume by a mean 28 mL (95% CI 24.7 to 31.7, p=0.002). Postoperatively, the aortic volume occupied by thrombus had decreased by a mean 11 mL (95% CI 4.7 to 18.2, p<0.001). There were good correlations between changes in aneurysm and thrombus volumes (r=0.864, p<0.001), between the planning CT/EVAS time interval and the change in aneurysm volume (r=0.640, p=0.001), and between the planning CT/EVAS time interval and the change in thrombus volume (r=0.567, p=0.003). CONCLUSION: There are significant changes in aortic volumes post EVAS. These changes may be a direct consequence of the technique and have implications for the planning and performance of EVAS.

Double Mesh Nitinol Stent Versus Self-expanding Stent-graft in Recurrent/Resistant Cephalic Vein Arch Stenoses in Dialysis Fistulae: A Comparative Study.

PURPOSE: To compare the double mesh nitinol stent (DNS) versus the self-expanding stent-graft (SES) in recurrent/resistant cephalic vein arch stenosis in dialysis fistulae. MATERIALS AND METHODS: 17 cases with recurrent/resistant stenosis of the cephalic vein arch treated with a DNS were compared retrospectively with 18 cases treated with an SES. Stenting was performed either for significant recoil post-angioplasty with high-pressure balloons or in recurrent stenoses. Patients were followed up with Doppler ultrasound in our vascular access surveillance programme. Primary and assisted primary patency rates at 3, 6 and 12 months were estimated by Kaplan-Meier analysis. RESULTS: Both stents showed 100% technical success immediately post-stenting, defined as residual stenosis < 30%. 3, 6 and 12 month primary patency of the DNS was 82.4%, 69.7% and 28.1% versus 88.9%, 77.8% and 72.2% for the SES. The DNS had a mean primary patency of 242.4 days compared to 896.3 days for the SES (p = 0.021). 12 month assisted primary patency was 88.2% (DNS) and 100% (SES). The DNS had a mean assisted primary patency of 812 days compared to 1390.3 days for the SES, though this did not reach statistical significance. No stent fractures were identified at 2 years in either group. CONCLUSION: Both stents had 100% technical success with no stent fractures. SES showed statistically significant higher primary patency. Assisted primary patency was also higher, though this did not reach statistical significance.

Radiologist variability in assessing the position of the cavoatrial junction on chest radiographs.

OBJECTIVE: To assess the variability in identifying the cavoatrial junction (CAJ) on chest X-rays (CXRs) amongst radiologists. METHODS: 23 radiologists (13 consultants and 10 trainees) assessed 25 posteroanterior erect CXRs (including 8 duplicates) and marked the positions of the CAJ. Differences in the CAJ position both within and between observers were evaluated and reported as limits of agreement (LOA), repeatability coefficients (RCs) and intraclass correlation coefficients and were displayed graphically with Bland-Altman plots. RESULTS: The mean difference for within-observer assessments was -0.2 cm (95% LOA, -1.5 to +1.1 cm) and between observers, it was -0.3 cm (95% LOA, -2.5 to +1.8 cm). Intraobserver RCs were marginally lower for consultants than for trainees (1.1 vs 1.5). RCs between observers were comparable (2.1 vs 2.2) for consultants and trainees, respectively. CONCLUSION: This study detected a large interobserver variability of the CAJ position (up to 4.3 cm). This is a significant finding considering that the length of the superior vena cava is reported to be approximately 7 cm. We conclude that there is poor consensus regarding the CAJ position amongst radiologists. ADVANCES IN KNOWLEDGE: No comparisons exist between radiologists in determining CAJ position from CXRs. This report provides evidence of the large observer variability amongst radiologists and adds to the discussion regarding the use of CXRs in validating catheter tip location systems.

ChEVAS: Combining Suprarenal EVAS with Chimney Technique.

Endovascular sealing with the Nellix(®) endoprosthesis (EVAS) is a new technique to treat infrarenal abdominal aortic aneurysms. We describe the use of endovascular sealing in conjunction with chimney stents for the renal arteries (chEVAS) in two patients, one with a refractory type Ia endoleak and an expanding aneurysm, and one with a large juxtarenal aneurysm unsuitable for fenestrated endovascular repair (EVAR). Both aneurysms were successfully excluded. Our report confirms the utility of chEVAS in challenging cases, where suprarenal seal is necessary. We suggest that, due to lack of knowledge on its durability, chEVAS should only been considered when more conventional treatment modalities (open repair and fenestrated EVAR) are deemed difficult or unfeasible.