Patient-specific computational flow simulation reveals significant differences in paravisceral aortic hemodynamics between fenestrated and branched endovascular aneurysm repair

Background

Endovascular aneurysm repair with four-vessel fenestrated endovascular aneurysm repair (fEVAR) or branched endovascular aneurysm repair (bEVAR) currently represent the forefront of minimally invasive complex aortic aneurysm repair. This study sought to use patient-specific computational flow simulation (CFS) to assess differences in postoperative hemodynamic effects associated with fEVAR vs bEVAR.

Methods

Patients from two institutions who underwent four-vessel fEVAR with the Cook Zenith Fenestrated platform and bEVAR with the Jotec E-xtra Design platform were retrospectively selected. Patients in both cohorts were treated for paravisceral and extent II, II, and V thoracoabdominal aortic aneurysms. Three-dimensional finite element volume meshes were created from preoperative and postoperative computed tomography scans. Boundary conditions were adjusted for body surface area, heart rate, and blood pressure. Pulsatile flow simulations were performed with equivalent boundary conditions between preoperative and postoperative states. Postoperative changes in hemodynamic parameters were compared between the fEVAR and bEVAR groups.

Results

Patient-specific CFS was performed on 20 patients (10 bEVAR, 10 fEVAR) with a total of 80 target vessels (40 renal, 20 celiac, 20 superior mesenteric artery stents). bEVAR was associated with a decrease in renal artery peak flow rate (-5.2% vs +2.0%; P < .0001) and peak pressure (-3.4 vs +0.1%; P < .0001) compared with fEVAR. Almost all renal arteries treated with bEVAR had a reduction in renal artery perfusion (n = 19 [95%]), compared with 35% (n = 7) treated with fEVAR. There were no significant differences in celiac or superior mesenteric artery perfusion metrics (P = .10-.27) between groups. Time-averaged wall shear stress in the paravisceral aorta and branches also varied significantly depending on endograft configuration, with bEVAR associated with large postoperative increases in renal artery (+47.5 vs +13.5%; P = .002) and aortic time-averaged wall shear stress (+200.1% vs -31.3%; P = .001) compared with fEVAR. Streamline analysis revealed areas of hemodynamic abnormalities associated with branched renal grafts which adopt a U-shaped geometry, which may explain the observed differences in postoperative changes in renal perfusion between bEVAR and fEVAR.

Conclusions

bEVAR may be associated with subtle decreases in renal perfusion and a large increase in aortic wall shear stress compared with fEVAR. CFS is a novel tool for quantifying and visualizing the unique patient-specific hemodynamic effect of different complex EVAR strategies.

Clinical Relevance

This study used patient-specific CFS to compare postoperative hemodynamic effects of four-vessel fenestrated endovascular aneurysm repair (fEVAR) and branched endovascular aneurysm repair (bEVAR) in patients with complex aortic aneurysms. The findings indicate that bEVAR may result in subtle reductions in renal artery perfusion and a significant increase in aortic wall shear stress compared with fEVAR. These differences are clinically relevant, providing insights for clinicians choosing between these approaches. Understanding the patient-specific hemodynamic effects of complex EVAR strategies, as revealed by CFS, can aid in future personalized treatment decisions, and potentially reduce postoperative complications in aortic aneurysm repair.

Preliminary experience with the new off-the-shelf 4 inner branches E-nside for the treatment of complex aortic disease

Objective

In case of complex aortic aneurysmal disease, fenestrated or branched EVAR (b/f-EVAR) is considered as a valid and safe alternative to open surgery. However, one the main limitation is the time required for manufacture, limiting its use in emergent situations. The new off-the-shelf 4 inner branches E-nside (Jotec, Hechingen, Germany) has been developed to offer a solution in such circumstances. The aim of this study was to report our preliminary monocentric experience with this new device.

Methods

Retrospective analysis of prospective data retrieved from 1 center between November 2020 and January 2022 was done. Endpoints were technical success, postoperative morbidity, rate of endoleak and any aneurysm-related re-interventions during follow-up.

Results

In this study, 15 patients (mean age 73 years, range 59–90) were identified. There was a majority of male (9/15) and all of them but 3 were asymptomatic. The mean aneurysmal diameter was 60 mm (range 50–100). There were 3 cases of juxtarenal aortic aneurysms (20%), 1 Crawford type I (7%), 4 type II (27%), 4 type III (27%) and 3 type IV (20%) aneurysms. In 7 cases, a 2-steps procedure was done with a TEVAR first followed by Enside implantation. There was a technical success in 93% with 1 open conversion for a mesenterical bypass. There was no death in the post-operative period. During the post-operative period, 33% of patients (5/15) presented complications with 3 complications related to the femoral or iliac access and 2 cases of spinal cord ischemia (13%). One case occurred in an emergent setting of a type III aneurysm rupture. The other case was the open conversion and the patient also developed a colic ischemia and finally died 4 months alter. The mean length of stay was 9 days. During the follow-up, 2 reinterventions were necessary, 1 for a type Ic endoleak with distal prolongation of the stent and 1 renal stent occlusion treated by relining. The overall target vessel patency was 98%.

Conclusion

The use of the off-the-shelf 4 inner branches E-nside appears to be safe with good technical success for the treatment of complex aortic aneurysmal disease. It is associated with an acceptable rate of complications and allows for treatment of a wide variety of diseases in an emergent setting. Further patients and longer follow-up are required to better evaluate the exact role of this new device.

Fenestrated endovascular repair with large device diameters (34- to 36-mm) is associated with type 1 and 3 endoleak and reintervention

OBJECTIVES

 Patients with abdominal aortic aneurysms undergoing EVAR with larger device diameters (34- to 36-mm) have worse outcomes due to proximal fixation failure and need for reintervention. We examine outcomes relating to standard fenestrated repair (FEVAR) with larger device diameters, and investigate whether a similar relationship exists.

MATERIAL AND METHODS

 Retrospective review of a prospectively maintained, single institution database of patients treated with the Cook ZFEN device between 2012-2017. Outcomes were stratified by device diameter into normal-diameter (ND,≤ 32 mm) and large-diameter (LD,34-36 mm). Primary endpoints were need for reintervention and composite type I/III endoleak.

RESULTS

 100 consecutive patients treated were identified for inclusion. Overall mean age was 73.6 years and mean aortic diameter was 59.1 mm. Mean follow-up was 22 months. A total of 26 (26%) patients were treated with LD devices. Number of target vessels per patient was 2.8 in both groups. Infrarenal neck length and diameter were significantly different in the LD and ND patients, respectively (2.6 mm vs 4.7 mm (P<.01) and 30.1 mm vs 23.4 mm (P<.01)). Percent graft oversizing was lower in the LD cohort (19% vs 24%; P=.006). No difference was seen in overall mortality at 30-days (0% vs 2%; P=.4) or at latest follow up (6% vs 14%; P=.6). Reinterventions were not significantly different at 30 days, but were significantly higher over the follow-up period in the LD cohort (46.2 vs. 17.6%; P=.002). LD diameter was associated with reintervention on univariate (HR 1.19, 95% CI 1.04-1.37), but not multivariate analysis. The composite endpoint of type I/III endoleak was higher in the LD cohort (15.4% vs. 2.7%; P=.004).

CONCLUSION

 FEVAR requiring 34- or 36-mm device diameters is associated with an increased risk of composite type I/III endoleak and reintervention. Patients undergoing fenestrated repair requiring LD devices should be closely monitored, with consideration for proximal or open repair.

Predictors of sac regression after fenestrated endovascular aneurysm repair

OBJECTIVE

Aneurysm sac regression after standard endovascular aortic repair is associated with improved outcomes, but similar data are limited after fenestrated endovascular aortic repair (FEVAR). We sought to evaluate sac regression after FEVAR, and identify any predictors of this favorable outcome.

METHODS

Patients undergoing elective FEVAR using the commercially available Zenith Fenestrated device (ZFEN; Cook Medical, Bloomington, IN) from 2012 to 2018 at a single institution were reviewed retrospectively. The maximal aortic diameter was compared between the preoperative scan and those obtained in follow-up. Patients with of 5 mm or more sac regression were included in the regression (REG) group, with all others in the nonregression (NONREG) group. Outcomes were compared between groups using univariate analysis, and logistic regression analysis was performed to identify any predictive factors for sac regression.

RESULTS

We included 132 patients undergoing FEVAR in the analysis. At a mean follow-up of 33.1 months, 65 patients (49.2%) had sac regression of 5 mm or more and comprised the REG group (n = 65 [49.2%]). The REG group had smaller diameter devices, and were less likely to have had concomitant chimney grafts placed (P < .05). The NONREG group had a higher incidence of type II endoleak (35.8% vs 12.3%; P = .002). Sac regression was associated with a significant mortality benefit on Kaplan-Meier analysis (log rank P = .02). Multivariate analysis identified adjunctive parallel grafting (odds ratio [OR], 0.01; 95% confidence interval [CI], 0.03-0.36; P < .01), persistent type II endoleak (OR, 0.13; 95% CI, 0.02-0.74; P < .01), and a greater number of target vessels (OR, 0.25; 95% CI, 0.10-0.62; P = .002) as independent predictors of failure to regress.

CONCLUSIONS

Sac regression after FEVAR occurred in nearly one-half of patients, but seems to be less common in patients with persistent type II endoleaks and those undergoing concomitant parallel grafting. Sac regression was associated with a significant survival advantage, and can be used as a clinical marker for success after FEVAR.

Multicenter observational study of the gore excluder conformable endograft for endovascular abdominal aortic repair: Initial results

Objective

Endovascular repair (EVAR) has become the standard of care for treatment of abdominal aortic aneurysms. However, a significant number of EVAR remains outside the IFU, especially in cases of severe proximal angulation (&gt;60 degrees), resulting in failure. The new device GORE EXCLUDER Conformable AAA Endoprosthesis (W. L. Gore & Associates, Flagstaff, Ariz) has been designed to accommodate neck angulation, due to conformability and angulation control. The aim of this multicenter study is to report the initial results of this device.

Methods

From March 2019 to January 2021, the data of all consecutive patients with AAA treated with the Gore Excluder Conformable endograft at 4 vascular centers were reviewed. Patients were followed using a standardized protocol, with CT-scan at 1, 6 and 12 months, and then yearly. The primary endpoint was technical success and secondary outcomes were postoperative morbidity, rate of endoleak (EL) and any aneurysm-related re-interventions during follow-up.

Results

Among the 32 patients included, most were men with a mean age of 77 years old (range 60-92). Half of patients were smokers and 72% had hypertension. The mean diameter of AAA was 62 mm (47-90). The mean length of aortic neck was 26 mm (10-69), the mean diameter 23 mm (16-31) and the median neck angulation was 81 degrees (range 40-110). The mean procedural duration was 102 min (54-153) with a mean time of scopy of 24 min (8-47) and a total volume of contrast of 101 ml (40-165). Thirteen iliac branch device have been used in 7 patients. The technical success was 97% with 1 type Ia EL (3%). In the post-operative period, 4 medical and 3 surgical complications were observed. Two reinterventions were needed with an iliac stenting for a stenosis and a correction of a femoral false aneurysm. During the mean follow-up of 7 months, 2 type Ia ELs were observed. One spontaneously resolved and the other one was followed. One distal limb extension was succesfully implanted at 3 months for a type Ib EL for a total rate of reintervention of 9%. No migration was observed. No death occured.

Conclusion

The use of the Gore Excluder Conformable endograft seems to be safe and effective in difficult anatomies and especially high angulation. It allows for precise deployment without the need for additional contrast or operation time. Longer follow-up and more patients are required to confirm these excellent initials results.

Renal Stent Complications and Impact on Renal Function after Standard Fenestrated Endovascular Aneurysm Repair

BACKGROUND

To report renal outcomes including long-term patency, secondary interventions, and related renal function after fenestrated endovascular aortic repair (fEVAR).

METHODS

Single-center retrospective review of patients undergoing fEVAR between 2012 and 2018 using the Cook ZFEN device. Renal stent complications, defined as any stenosis, occlusion, kink, renal stent-related endoleak, and reinterventions were tabulated. Estimated glomerular filtration rate (eGFR) was estimated using the Modification of Diet in Renal Disease formula.

RESULTS

During the study period, 114 patients underwent elective fEVAR. Of 329 total target vessels, 193 renal arteries were stented (133 Atrium iCAST, 60 Gore VBX). Technical success was achieved in 97.4%, and the mean follow-up was 23.3 months. Seventeen renal complications occurred in 14 patients (12.3%), including 4 occlusions, 9 stenosis, 3 dislocations, and 1 type III endoleak. All stent complications underwent endovascular reintervention with a median hospital stay of 1 day (0-10) and a technical success of 94.2%. One patient suffered renal hemorrhage that warranted embolization. Patients with occlusion were treated the day of diagnosis, and mean time from diagnosis to intervention for stenosis was 21.5 days. Estimated primary patency was 92.1 % and 81.5% at 24 and 48 months, respectively. On multivariate analysis, larger native renal artery diameter was the only independent protective factor against patency loss (HR 0.23 (0.09-0.59)). Secondary patency at latest follow-up was 99.4%. Mean eGFR was not significantly different at latest follow-up between patients with renal complications versus those without (43.75 vs. 55.58 mL/min/1.73 m², P = 0.09). Comparing patients with and without renal stent complications, 81.4% and 72.7% of patients had stable or improved renal disease by chronic kidney disease staging compared with baseline (P = 0.51).

CONCLUSIONS

fEVAR is a durable option for the treatment of juxtarenal aortic aneurysms and is associated with excellent secondary patency. Renal stent complications have no significant impact on renal function, but smaller native renal arteries are at higher risk of stent-graft complications.

Quantification of suprarenal aortic neck dilation after fenestrated endovascular aneurysm repair

OBJECTIVE

Suprarenal aortic neck dilation (AND) after fenestrated endovascular aneurysm repair (FEVAR) with commercially available devices has not yet been well characterized. The aim of this study was to measure diameter changes in the supravisceral aorta after FEVAR.

METHODS

This is a single-center retrospective review involving patients with juxtarenal aneurysms treated with Cook ZFEN devices (Cook Medical, Bloomington, Ind). Patients with at least 1 year of cross-sectional radiologic follow-up were included. AND was defined as ≥3 mm at any measured location. Aortic diameter, defined as the average outer to outer diameter on three-dimensional centerline imaging, was measured at seven locations along the length of the ZFEN device from the proximal fixation struts to the bottom of the second seal stent. The first postoperative CT scan (≤1 month) served as a baseline from which subsequent measurements at annual intervals were compared.

RESULTS

A total of 43 patients who underwent FEVAR from 2012 to 2018 met inclusion criteria, with a total of 119 target vessels (83 renal stents, 41 superior mesenteric artery scallops or large fenestrations). Mean follow-up time was 30.3 months. Any AND was found to occur in 32 (74.4%) patients. Aortic diameter dilation at latest follow-up was found to occur at all measured locations from the top of the fixation struts (1.9 ± 2.4 mm; P < .0001) to the middle of the second seal stent (1.3 ± 3.8 mm; P < .01). Diameter growth was most pronounced in the middle of the first seal stent, with mean AND of 3.6 ± 3.2 mm. At this location, the aorta experienced nearly linear annual growth of 0.99 mm (95% confidence interval, 0.7-1.28 mm) per year. Increasing device oversizing relative to the native visceral aorta was the strongest predictor of postoperative neck diameter growth (1.34 mm per 10% increase in oversizing; P = .02), whereas increasing proximal seal length was protective of growth (-1.82 mm per 10-mm increase in seal length; P = .016). Proximal seal lengths ≥3 cm were associated with less neck dilation compared with <3 cm (2.6 mm vs 4.9 mm; P = .022). Type IA endoleak in this cohort was rare (n = 1) and not associated with AND (P = .256).

CONCLUSIONS

Dilation of the suprarenal aorta is a common finding in midterm follow-up after FEVAR and not associated with proximal endoleak. Aggressive device oversizing is predictive of dilation, whereas longer seal lengths are associated with less dilation along the suprarenal seal zone. These results support the continued use of FEVAR for juxtarenal aneurysms, particularly in patients in whom ≥3 cm of healthy seal length can be obtained.

Long-term Functional Outcomes Follow-up after 188 Rib Resections in Patients with TOS

BACKGROUND

Short-term outcomes in patients with all forms of TOS have been widely reported in the literature and have established that rib resection can be beneficial in decompressing the thoracic outlet and relieving pressure on traversing structures. We sought to determine long-term functional outcomes using the Disability of the Arm, Shoulder, and Hand (QuickDASH) survey in patients with TOS who underwent rib resection.

METHODS

Clinical records for patients who underwent rib resection for TOS at a single institution were retrospectively reviewed. All patients were contacted via telephone and long-term functional outcome was assessed at latest follow-up via the 11-item version of the QuickDASH questionnaire. Demographics, TOS type, preoperative QuickDASH score, and athletic status were recorded. Patients were asked if they returned to baseline activity since their surgery, would have the procedure again, and if they were subjectively better postoperatively.

RESULTS

From 2000 to 2018, 261 patients underwent rib resection surgery. One hundred seventy patients (65.1%) were able to be contacted via telephone for long-term follow-up. A total of 188 surgeries (102 neurogenic thoracic outlet syndrome, 82 venous thoracic outlet syndrome, 4 arterial thoracic outlet syndrome) were performed in these 170 patients. The mean follow-up time for the cohort was 5.3 years (range 1-18). Overall, 167 (88.9%) patients returned to baseline activity postoperatively. Postop QuickDASH decreased to 12 from 44 preoperatively for the cohort.

CONCLUSIONS

First rib resection and thoracic outlet decompression for all forms of TOS is a durable surgical treatment which results in excellent long-term functional outcomes as determined by both the QuickDASH score and subjective patient reporting.

Incidence and Risk Factors for Deep Vein Thrombosis after Radiofrequency and Laser Ablation of the Lower Extremity Veins

BACKGROUND

The rates of thromboembolic complications such as deep vein thrombosis (DVT) after venous ablation procedures for symptomatic superficial venous insufficiency are controversial. We sought to describe the risk factors for and incidence of DVT after radiofrequency ablation (RFA) and laser ablation (LA).

METHODS

We queried the Truven Health Marketscan Database from 2007-16 for patients who underwent RFA or LA and had a follow-up duplex ultrasound within 30 days of the ablation procedure. The primary outcome was DVT at 7 and 30 days identified by International Classification of Diseases-9 and International Classification of Diseases-10 codes. Multivariable regression was used to evaluate the patient and procedural variables associated with a DVT at 30 days, expressed as odds ratios (ORs) with a 95% confidence interval (95% CI). Patients and procedures with a previous DVT diagnosis were excluded.

RESULTS

A total of 256,999 patients underwent 433,286 ablation procedures: 192,195 (44.4%) RFA and 241,091 LA. Of these, 8,203 (1.9%) had a newly diagnosed DVT within 7 days and 13,347 (3.1%) within 30 days of the procedure. The incidence of DVT decreased over the study period. LA (2.8%) demonstrated a lower incidence of DVT at 30 days compared with RFA (3.4%), P < 0.001. On multivariable regression, LA (OR, 0.82; 95% CI 0.80-0.85) was again associated with a decreased risk for 30-day DVT, as was female gender (OR, 0.74; 95% CI, 0.71-0.77), and sclerotherapy performed on the same day (OR, 0.91; 95% CI, 0.85-0.98). A diagnosis of peripheral artery disease (OR, 1.23; 95% CI, 1.16-1.31) and concomitant stab phlebectomy (OR, 1.43; 95% CI, 1.37-1.49) was associated with an increased risk of DVT within 30 days.

CONCLUSIONS

The incidence of newly diagnosed DVT within 30 days of an ablation procedure was 3.2%. The risk for DVT decreased in recent years, and LA was associated with an 18% decreased risk compared with RFA.

Multivessel tibial revascularization does not improve outcomes in patients with critical limb ischemia

OBJECTIVE

Multivessel tibial revascularization for critical limb ischemia (CLI) remains controversial. The purpose of this study was to evaluate single vs multiple tibial vessel interventions in patients with multivessel tibial disease. We hypothesized that there would be no difference in amputation-free survival between the groups.

METHODS

Using the Vascular Quality Initiative registry, we reviewed patients undergoing lower extremity endovascular interventions involving the tibial arteries. Patients with CLI were included only if at least two tibial vessels were diseased and adequate perioperative data and clinical follow-up were available for review. The primary outcome was amputation-free survival.

RESULTS

There were 10,849 CLI patients with multivessel tibial disease evaluated from 2002 to 2017; 761 limbs had adequate data and follow-up available for review. Mean follow-up was 337 ± 62 days. Of these, 473 (62.1%) underwent successful single-vessel tibial intervention (group SV), whereas 288 (37.9%) underwent successful multivessel (two or more) intervention (group MV). Patients in group MV were younger (69.1 vs 73.2 years; P < .001), with higher tobacco use (29.5% vs 18.2%; P < .001). Group SV more commonly had concurrent femoral or popliteal inflow interventions (83.7% vs 78.1%; P = .05). Multivessel runoff on completion was significantly greater for group MV (99.9% vs 39.9%; P < .001). No differences were observed between group SV and group MV for major amputation (9.0% and 7.6%; P = .6), with similar amputation-free survival at 1 year (90.6% vs 92.9%; P = .372). In a multivariate Cox model, loss of patency was the only significant predictor of major amputation (hazard ratio, 5.36 [2.7-10.6]; P = .01). A subgroup analysis of 355 (46.6%) patients with tissue loss data showed that tissue loss before intervention was not predictive of future major amputation.

CONCLUSIONS

In the Vascular Quality Initiative registry, patients with CLI and occlusive disease involving multiple tibial vessels did not appear to have a limb salvage benefit from multiple tibial revascularization compared with single tibial revascularization.

Ten Year Experience of Using Cryopreserved Arterial Allografts for Distal Bypass in Critical Limb Ischaemia

OBJECTIVE/BACKGROUND

In critical limb ischaemia (CLI), current guidelines recommend revascularisation whenever possible, preferentially through endovascular means. However, in the case of long occlusions or failed endovascular attempts, distal bypasses still have a place. Single segment great saphenous vein (GSV), which provides the best conduit, is often not available and currently there is no consensus about the best alternative graft.

METHODS

From January 2006 to December 2015, 42 cryopreserved arterial allografts were used for a distal bypass. Autologous GSVs or alternative autologous conduits were unavailable for all patients. The patients were observed for survival, limb salvage, and allograft patency. The results were analysed with Kaplan-Meier graphs.

RESULTS

Estimates of secondary patency at one, two and five years were 81%, 73%, and 57%, respectively. Estimates of primary patency rates at one, two and five years were 60%, 56%, and 26%, respectively. Estimates of limb salvage rates at one, two and five years were 89%, 89%, and 82%, respectively. Estimates of survival rates at one, two and five years were 92%, 76% and 34%, respectively. At 30 days, major amputations and major adverse cardiac events were one and zero, respectively. Six major amputations occurred during the long-term follow up.

CONCLUSION

Despite a low primary patency rate at two years, the secondary patency of arterial allografts is acceptable for distal bypasses. This suggests that cryopreserved arterial allografts are a suitable alternative for limb saving distal bypasses in the absence of venous conduits, improving limb salvage rates and, possibly, quality of life.