Thrombus Load May Predict Worse Outcome after EVAR

New research in the current issue of JVIR evaluated the impact of two- and three-dimensional preoperative morphologic assessment on CTA on midterm outcomes in patients with AAA treated with EVAR. Sirignano et al., retrospectively evaluated morphologic features of AAA including maximum aortic diameter, thrombus area, overall aneurysm volume, and intrasac thrombus volume (1). This was compared with all perioperative and midterm AAA-related re-intervention and all-cause mortality. Investigators reviewed 191 pre-op CTAs with mean maximum aortic diameter of 58 mm; thrombus area, 49.6%; aortic volume, 159.36 cm3; and thrombus volume, 58.6%. There were no reported cases of re-intervention or mortality in the perioperative period. Mean follow-up was 32 months +/- 16.8 months (range, 3-66 months) with a mortality rate of 9.4%. AAA-related death was 0 and re-intervention rate was a low 8.9%. Causes of re-intervention included type I endoleak (n=3 [1.6%]), type II endoleak (n=7 [3.7%]), type III endoleak (n=1 [0.5%]), endograft limb thrombosis (n=4 [2.1%]), and access vessel thrombosis (n=2; 1%). Predictors for re-intervention included greater thrombus area (>60%) and thrombus volume (>59%). While greater maximum aortic diameter (>59 mm) and aortic volume (>159 cm3) trended to higher reintervention rate, the results were not statistically significant (P=.62 and P =.12). Aortic volume was a predictor of any adverse event, re-intervention, and all-cause mortality after EVAR (P=.03). The authors concluded that thrombus area and volume are risk factors for higher rates of re-intervention and do not represent a protective factor.

Commentary:

The above article is noteworthy as it challenges a commonly held assumption regarding sac thrombus and re-intervention rates. While previous work (2, 3) has suggested that thrombus load is actually protective of future interventions (namely type II endoleak), the current manuscript has shown that this assumption may not be valid. However, the current study has a smaller sample size and a lower rate of re-intervention (8.9% vs 15.4%) when compared with prior work. Further, earlier research focused more on presence or absence of endoleak rather than growth or shrinkage of sac size. Additionally, given changes in device design, one may argue how comparable two sample cohorts from >10yrs apart are. Lastly, given the large number of variables present (neck angulation, neck length, presence or absence of patent vessels within the sac, etc.) it may be difficult to tease out meaningful conclusions from a small data set. Regardless, if nothing else, the questions raised in the manuscript point to the continued need for research in this challenging patient population.

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1. Sirignano, et al. Preoperative intrasac thrombus load predicts worse outcome after elective endovascular repair of abdominal aortic aneurysms. J Vasc Interv Radiol 2015; 26:1431-6. 

2. Rai D, Wisniowski B, Bradshaw B, et al. Abdominal aortic aneurysm calcification and thrombus volume are not associated with outcome following endovascular abdominal aortic aneurysm repair. Eur Radiol 2014; 24:1768–1776. 28. 

3. Sampaio SM, Panneton JM, Mozes GI, et al. Aneurysm sac thrombus load predicts type II endoleaks after endovascular aneurysm repair. Ann Vasc Surg 2005; 19:302–309.


Post Author:
Luke R. Wilkins, MD

Fixing Visceral Pseudoaneurysms with N-Butyl Cyanoacrylate Glue

Recent research from Madhusudhan, et al. has demonstrated that conventional wisdom may not always apply to every visceral aneurysm undergoing endovascular repair. In an upcoming article from JVIR, the group reports their retrospective review of 31 patients with visceral PSAs treated with NBCA. Common indications for using glue included preservation of a major feeding artery, difficult catheterization secondary to arterial tortuosity, failed coil embolization, and short landing zone for coils. The mean amount of glue used was a surprisingly petite 0.24 mL (range, 0.1-1.1 mL). Immediate technical success was seen in all patients with recurrence in 3 (9.7%) and overall clinical success in 90.3%. Major complications were seen in 3 patients (9.7%) and included nontarget embolizations to liver and spleen as well as catheter adhesion and fracture. The authors used a modified technique for glue injection with no more than 0.3 mL (3:7 ratio of NBCA to lipiodol) injected at one time. The aliquots of glue were flushed from the deadspace of the catheter with 50% dextrose until it opacified the PSA. The sequence was then repeated until embolization was complete. The authors concluded that NBCA is a safe and effective embolization agent for treatment of PSA.

Commentary:

The endovascular repair of visceral pseudoaneurysms encompasses a heterogenous set of technical challenges that have been well described using conventional techniques of coil embolization. In the majority of cases, classic coil embolization to exclude the PSA is both technically achievable and well tolerated. However, in a minority of cases, this approach may not be possible secondary to anatomic challenges. Alternative techniques to overcome these challenges include covered stent placement and stent-assisted coil embolization. With NBCA, the interventionalist has yet another tool to overcome these often challenging cases. The authors’ description and figures highlighting potential complications associated with use of NBCA for PSA repair highlight the need for the operator to be familiar and experienced in the use of this embolization agent prior to its use in these challenging circumstances.

Figure 2. Preservation of major feeding artery. A 40-year-old woman presented with acute gastrointestinal bleeding after cholecystectomy. (a) DSA image showing PSA (arrow) arising from the right posterior hepatic artery. (b) Image obtained after embolization showing NBCA cast in the PSA (arrow) with microcatheter in situ. (c) Image obtained after embolization showing preserved divisions of the right hepatic artery (white arrows) with nonopacification of the PSA (black arrow). Use of a microcoil in this case would have occluded the right posterior hepatic artery with risk of hepatic ischemia/infarct. Use of NBCA preserved the artery.

Figure 6. Complications. (a) Reflux of NBCA into the branches of the right hepatic artery (arrows) during embolization of cystic artery PSA (arrowhead). (b) Reflux of NBCA into branches of the splenic artery (arrow) during embolization of splenic artery PSA (arrowhead). (c) Microcatheter fracture in the splenic artery (white arrows) with NBCA cast (black arrows).

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Madhusudhan KS, et al. Endovascular embolization of visceral artery pseudoaneurysms using a modified injection technique with N-Butyl cyanoacrylate glue. Journal of Vascular and Interventional Radiology 2015. DOI: 10.1016/j.jvir.2015.07.008

Post Author:
Luke R. Wilkins, MD

New Data Supports Use of Vascular Plug-Assisted Retrograde Transvenous Obliteration (PARTO) for the Treatment of Gastric Varices and Hepatic Encephalopathy

A new prospective, multicenter study from investigators in Korea supports the use of PARTO in the treatment of GVs and HE. 73 consecutive patients were included from two institutions. 57 of the 73 patients had GVs with 28 in danger of rupture, 23 with recent bleeding, and 6 with active bleeding. 16 of the 73 were done for HE recalcitrant to medical therapy. The study reported a 100% technical success rate with no procedure-related complications. A 1 week follow-up CT was obtained and showed complete thrombosis in 72 of 73 patients (98.6%). 60 patients had follow-up to at least 3 months and all 60 showed complete obliteration. Of this group of 60 patients, there was no development of rebleeding or HE at end of follow-up. The authors concluded that PARTO can be “rapidly performed with high technical success and durable clinical efficacy for the treatment of GVs and HE in the presence of a portosystemic shunt.”

Comment:

This is the first, prospective multicenter trial evaluating PARTO in the treatment of GVs and HE in patients with a portosystemic shunt. Previous work by Gwon et al. discussed the use of PARTO in a limited number of patients and in a retrospective fashion. While BRTO has been considered a first-line treatment in the appropriate patients, the present manuscript makes a strong argument to consider PARTO in more patients. Clear advantages include logistical issues related to prolonged balloon inflation as well as the relative safety of PARTO when compared with BRTO. However, there are anatomical and clinical considerations that should be made. There are instances when it is not anatomically feasible to get an appropriately sized sheath into the shunt deep enough to deploy the Amplatzer. Further, while the data of the present study indicate that the nidus of the varix was appropriately embolized, it would seem intuitive that the foam sclerosant of BRTO would more effectively and efficiently treat the varix when compared with a gelfoam slurry given its ability to travel into smaller vessels in a more effective manner. Lastly, the patient population presented in the current manuscript is likely different than the population treated in North America and Europe and this will likely impact results as well. Regardless, the results are compelling and warrant careful consideration and further research.




Images from a 55-year-old man with GVs. (a) Contrast-enhanced CT obtained before PARTO shows GVs (asterisk). Note the hypertrophied left gastric vein (arrowhead). (b) After placement of the vascular plug (white arrow) within the narrowest portion of the portosystemic shunt via the left adrenal vein, additional embolization of the gastrorenal shunt, GVs (asterisk), and left gastric vein (arrowhead) was performed by using gelatin sponge particles through the 4-F catheter (black arrow). (c) Contrast-enhanced CT scan obtained 3 months after PARTO shows complete obliteration of the GVs.

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Gwon, et al. Vascular Plug–Assisted Retrograde Transvenous Obliteration for the Treatment of Gastric Varices and Hepatic Encephalopathy: A Prospective Multicenter Study. Journal of Vascular and Interventional Radiology 2015. DOI: 10.1016/j.jvir.2015.07.011

Post Author:
Luke R. Wilkins, MD