A novel endovascular debranching technique using physician-assembled endografts for repair of thoracoabdominal aneurysms

Single-Site Review of Spinal Cord Protection Protocols Including the Utilization of Spinal Drains versus Medical Management with Branched Endovascular Aortic Repair

BACKGROUND

Spinal cord ischemia (SCI) continues to be a devastating complication after repair of thoracoabdominal aortic aneurysms. The objective of this review is to present our single-center outcomes after the implementation of a standardized neuroprotective protocol following branched endovascular aortic repair.

METHODS

A standardized neuroprotective protocol including preoperative steroids, acetazolamide, intraoperative hemodynamic parameters, and postoperative treatment goals was initiated in November 2019. Physician-modified branched endovascular repairs were completed at a single center from 2012 to 2021 with outcomes reviewed both before (n = 107) and after (n = 67) the implementation of the neuroprotective protocol. The primary end point was the incidence of any SCI event at 30 days. Secondary end points included all-cause mortality, stroke, myocardial infarction, and renal failure at 30 days. Patients with Crawford extents I-III, renal failure, or necessitating emergent repair were deemed high risk for SCI events and underwent a subset analysis. Survivability after SCI was estimated using Kaplan-Meier tables.

RESULTS

Of the 174 consecutive patients treated, the 67 patients treated following implementation of the neuroprotective protocol were more likely to have experienced a prior myocardial infarction (26.9% vs. 14%; P = 0.0466) and have a history of chronic obstructive pulmonary disease (64.3% vs. 45.8%; P = 0.02). This group was more likely to be treated for paravisceral aneurysms (53.7% vs. 24.3%; P = 0.0002). Postprotocol implementation, spinal drain use was lower (6% vs. 38.3%; P = <0.0001) with 100% of these drains placed in urgent or unstaged thoracoabdominal aortic aneurysm repairs as a part of the protocol. Rates of any SCI event among all patients before and after implementation of the protocol were 9.3% (n = 10 of 107) and 6% (n = 4 of 67; P = 0.57), respectively. In comparison, the protocol significantly reduced SCI rates to 0 (0% vs. 17.1%; P = 0.0407) in high-risk patients. Frequency of renal failure was reduced (3% vs. 14%; P = 0.018) after initiation of the protocol. Patients in the postprotocol group had significantly improved 1-year mortality rate (9% vs. 27.1%; P = 0.0035) and renal failure rates (2% vs. 15%; P = 0.018). Regression models indicated that patients in the postprotocol group had lower likelihood of mortality and renal failure than patients in preprotocol group (P < 0.05) and that spinal drain reduced mortality (P < 0.1).

CONCLUSIONS

Implementation of a standardized neuroprotective protocol that focuses on medical management and fluid dynamics may significantly reduce risk of SCI after branched endovascular repairs, with the most significant improvement of SCI outcomes involving those at greatest risk for developing SCI. Also noteworthy, there was significant improvement to 1-year survivability after the implementation of this neuroprotective protocol.

Incidence of Acute and Chronic Renal Failure Following Branched Endovascular Repair of Complex Aortic Aneurysms

BACKGROUND

The purpose of this study was to examine the incidence of acute kidney injury and chronic renal impairment following branched endovascular aneurysm repair (BEVAR) of complex thoracoabdominal aortic aneurysms (TAAA) using the Medtronic Valiant Thoracoabdominal Aortic Aneurysm stent graft system (MVM), the physician-modified Visceral Manifold, and Unitary Manifold stent graft systems. The objective was to report the acute and chronic renal function changes in patients following complex TAAA aneurysm repair.

METHODS

This is an analysis of 139 patients undergoing branched endovascular repair for complex TAAAs between 2012 and 2020. Patient renal function was evaluated using serum creatinine and estimated glomerular filtration rate at baseline, 48 hr, discharge, 1 month, 6 months, and annually to 2 years. Patients on dialysis prior to the procedure were excluded from data analysis.

RESULTS

A total of 139 patients (mean age 71.13; 64.7% male) treated for TAAA with BEVAR met inclusion criteria and were evaluated. A total of 530 visceral vessels were stented. A majority of patients (n = 131, 94.2%) underwent a single procedure while 8 required staged procedures. Thirty-day, 1-year and 2-year all-cause mortality rates were 5.8%, 25.2%, and 32.4%, respectively. Primary and secondary patency rates at a median follow-up of 26.9 months (95% CI; 21.1 - 32.7) were 96.2% and 97.5% for all vessels and 95.4% and 96.9% for renal arteries, respectively. Postoperative acute kidney injury (AKI) was identified in 22 (15.8%) patients. At discharge, 16 patients (11.6%) had an increase in CKD stage with 3 requiring permanent dialysis. Five additional patients required permanent dialysis over the 2-year follow-up period for a total of 8 (5.8%). Increasing age (HR = 1.0327, P= 0.0477), hemoglobin < 7 prior to procedure (HR = 2.4812, P= 0.0093), increasing maximum aortic diameter (HR = 1.0189, P= 0.0084), presence of AKI (HR = 2.0757, P= 0.0182), and increase in CKD stage (HR = 1.3520, P= 0.002) at discharge were significantly associated with decreased patient survival.

CONCLUSIONS

Postoperative AKI and a chronic decline in renal function continue to be problematic in endovascular repair of complex aortic aneurysms. This study found that BEVAR using the manifold configuration resulted in immediate and mid-term renal function that is comparable to similar analyses of branched and/or fenestrated grafts.

Hemodynamic Parameters Predict In-stent Thrombosis After Multibranched Endovascular Repair of Complex Abdominal Aortic Aneurysms: A Retrospective Study of Branched Stent-Graft Thrombosis

Background: Branch vessel occlusion is reported in endovascular repair of aortic pathology. This study aimed to evaluate the hemodynamic indicators associated with in-stent thrombosis (IST) of a branched stent-graft (BSG) after endovascular aortic repair (EVAR) of a complex abdominal aortic aneurysm.

Methods: A retrospective evaluation was performed based on the computed tomography (CT) scans and clinical data of three patients who underwent multi-branched endovascular repair. Patient-specific 3-dimensional models were reconstructed, and hemodynamic analysis was performed for IST. Hemodynamics-related parameters including time-averaged wall shear stress (TAWSS), oscillatory shear stress index (OSI), and relative residence time (RRT) were compared among the individual patients.

Results: The flow velocity, TAWSS, OSI, and RRT were radically changed in the area of the IST. In BSGs, IST tended to occur in the regions of hemodynamic alteration near the bends in the device, where a decreased flow velocity (<0.6 m/s) and TAWSS (<0.8 Pa) and an elevated OSI (>0.2) and RRT (>5 s) were consistently observed.

Conclusions: Hemodynamic perturbations in BSGs cause a predisposition to IST, which can be predicted by a series of changes in the flow parameters. Early hemodynamic analysis might be useful for identifying and remediating IST after multibranched endovascular repair.

Combination of mural thrombus and age improves the identification of all-cause mortality following branched endovascular repair

BACKGROUND

In-hospital and 30-day mortality rates of endovascular repair of thoracoabdominal aortic aneurysms shows a significant improvement over open surgery, although we are not seeing a significant difference at 1 year. We assess the hypothesis that a greater mural thrombus ratio within the aorta could function as an indicator of postoperative mortality.

METHODS

The mural thrombus ratio and preoperative comorbidities of 100 consecutive patients from a single center undergoing endo-debranching between 2012 and 2019 were evaluated. Logistic regression, survival analysis, and decision tree methods were used to examine each variable's association with death at 1 year.

RESULTS

At the time of analysis, 73 subjects had 1-year outcomes and adequate imaging to assess the parameters. At 1 year, the overall survival for all subjects was 71.2% (21 died, 52 survived). For patients with a favorable mural thrombus ratio (n = 36), the overall 1-year survival was 86.1% (5 died, 31 survived). The subjects with an unfavorable mural thrombus ratio (n = 37), had an overall 1 year survival of 56.8% (16 died, and 21 survived). The only preoperative mortality factor that was statistically significant between the subjects with an unfavorable mural thrombus ratio was age of the patient. The survival for subjects 75 years and older with an unfavorable mural thrombus ratio was 90% (one died, nine survived) vs only 44.4% survival for subjects less than 75 years with an unfavorable mural thrombus ratio (15 died, 12 survived).

CONCLUSIONS

This study examined whether a patient's mural thrombus ratio may be an indicator of 1-year survival. These findings suggest that the combination of a patient's aortic mural thrombus ratio and age can function as a preoperative indicator of their underlying cardiac reserve. Identifying patients with low cardiac reserve and fitness to handle the increased cardiac demands owing to the physiologic response to extensive aortic stent grafting before undergoing aortic repair may allow for modification of preoperative patient counseling and postoperative care guidelines to better treat this patient population.

A novel physician-assembled endograft for the repair of pararenal, paravisceral, Crawford type IV thoracoabdominal aortic aneurysms, and aneurysms requiring treatment after prior repair

OBJECTIVE

In the present study, we reviewed the 30-day and 1-year clinical results of the use of the investigational unitary manifold (UM) stent graft system (Sanford Health, Sioux Falls SDak) for the repair of Crawford type IV, pararenal, paravisceral, juxtarenal, and short-neck infrarenal aneurysms (<10 mm).

METHODS

The present study was a single-center, multiarm, prospective review of the first 44 patients who had undergone repair of Crawford type IV, pararenal, juxtarenal, and short-neck infrarenal aneurysms (<10 mm) using the physician-modified UM under a physician-sponsored investigational device exemption. The primary end point was freedom from major adverse events at 30 days, including all-cause mortality, myocardial infarction, stroke, paraplegia, bowel ischemia, respiratory failure, and renal failure.

RESULTS

Technical success was achieved in all 44 patients (100%), with a large number of these patients having undergone previous aortic repair (20 of 44; 45.5%). All the intended 170 visceral vessels (100%) had been successfully cannulated and stent grafted. No episodes of paraplegia or in-hospital deaths were recorded. One patient had died of aneurysm-related ischemic stroke (2.3%). The rate of transient nonclinically significant spinal cord ischemia was 4.5%. At the last follow-up, one reintervention had been required owing to branch patency from a thrombotic event. Of the 170 bridging stent grafts, 169 have remained patent through a mean follow-up of 8.8 months (range, 0-36 months). No type I or III endoleaks, migration, or component separation in the investigational device has occurred.

CONCLUSIONS

The early and midterm results with the use of the UM suggest it could be a viable option for the repair of Crawford type IV, pararenal, paravisceral, juxtarenal, and short-neck infrarenal aneurysms (<10 mm) without exposing patients to the increased risk of permanent spinal cord ischemia, renal failure, visceral vessel ischemia, or aneurysm-related mortality that results from open thoracoabdominal aortic aneurysm repair. The high technical success rate, in native and previous repairs, supports the utility of this device as a bail-out technique for failed endovascular aneurysm repair or proximal extension of disease after previous aortic repair. However, experience is limited, and this approach requires further study before widespread adoption.

Acute Kidney Injury after Complex Endovascular Aneurysm Repair

Background:

Complex endovascular repair of abdominal aortic aneurysm carries higher perioperative morbidity than standard infrarenal endovascular repair.

Objective:

This study reviews the incidence and associated factors of acute kidney injury in complex aortic endovascular repair of juxtarenal, pararenal, and thoracoabdominal aortic aneurysms.

Methods:

A literature review was performed for all studies on the endovascular repair of juxtarenal, pararenal, and thoracoabdominal aneurysms that evaluated rates of acute kidney injury as an outcome. Outcomes were further analyzed by the level of anatomic complexity and method of repair.

Results:

52 studies met inclusion criteria, with a total of 5454 individuals undergoing repair from 2004 to 2017. The overall rate of acute kidney injury ranged widely from 0 to 41%, with a rate of hemodialysis from 0 to 19% (temporary) and 0 to 14% (permanent). Increasing anatomic complexity was associated with higher rates of acute kidney injury. Mode of endovascular repair, learning curve effect, and preoperative chronic renal insufficiency did not demonstrate any associations with the outcome.

Conclusion:

Published rates of acute kidney injury in complex aortic aneurysm repair vary widely with few definitively associated factors other than increasing anatomic complexity and operative time. Further study is needed for the identification of predictors related to postoperative acute kidney injury.

A clinical review of early outcomes from contemporary flow modulation versus open, fenestrated and branch technologies in the management of thoracoabdominal aortic aneurysm

Traditional therapeutic options for complex thoracoabdominal aneurysm include open repair, hybrid repair or endovascular repair (involving fenestrated or branched endografts). The Streamliner Multilayer Flow Modulator has been available for treatment of thoracoabdominal aneurysms since 2010. Its design permits blood flow to perfuse through the mesh in a modus that preserves collateral branch patency, while modulating turbulent to laminar flow within the device. The flow then stagnates over time within the surrounding aneurysm sac. Significant complications, including paraplegia, renal failure and cerebrovascular accident, are much lower with Streamliner Multilayer Flow Modulator treatment. Application of the Streamliner Multilayer Flow Modulator to complex aortic pathologies presents a novel solution to an, as of yet, unmet clinical need, and has resulted in promising clinical outcomes when compared to existing solutions. The Streamliner Multilayer Flow Modulator offers potential for treatment of thoracoabdominal aortic pathologies in patients and is not just confined to those with complexity that dictates no other management options. While current literature illustrates that there is a decreased risk of mortality and associated complications when this new disruptive technology is utilised, there is still a need for prospective, long-term clinical trials, as well as comparative trials to accurately assess outcomes of Streamliner Multilayer Flow Modulator treatment that are both precise and reproducible. This article is a review of current clinical literature regarding contemporary flow modulating technology compared with open, branched and fenestrated managements, presenting early outcomes.

Examination of near-wall hemodynamic parameters in the renal bridging stent of various stent graft configurations for repairing visceral branched aortic aneurysms

OBJECTIVE

This study examined the flow behavior of four stent graft configurations for endovascular repair of complex aneurysms of the descending aorta.

METHODS

Computational fluid dynamics models with transient boundary conditions and rigid wall simplifying assumptions were developed and used with four distinct geometries to compare various near-wall hemodynamic parameters.

RESULTS

Graphic plots for time-averaged wall shear stress, oscillating shear index, and relative residence time were presented and compared among the four stent graft configurations of interest.

CONCLUSIONS

Abrupt 90° and 180° changes in stent geometry (particularly in the side branches) cause a high momentum change and thus increased flow separation and mixing, which has significant implications in blood flow characteristics near the wall. By comparison, longer bridging stents provide more gradual changes in momentum, thus allowing blood flow to develop before reaching the target vessel.

Description of a new technique for repairing chronic type B dissections that involve visceral branches being fed by both true and false lumen by using both lumens as conduits

Here we present three cases performed using a novel technique where aortic flow is compartmentalized proximal to the target vessels through a physician-modified endograft. The visceral segment is then further compartmentalized by the use of another physician modified endograft. By compartmentalizing the flow proximal to the visceral segment, both the true lumen and false lumen can be used as conduits for coextensive bridging stent grafts. Overall, patients have tolerated this procedure extremely well, and while further study and follow-up must be conducted, this procedure could offer a reasonable long-term solution to thoracoabdominal aortic aneurysms complicated by dissection.