Distal Stent Graft-Induced New Entry: An Emerging Complication of Endovascular Treatment in Aortic Dissection

The Year in Vascular Anesthesia: Selected Highlights From 2018

This special article is the second in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia that is specifically dedicated to highlights in vascular anesthesiology published in 2018. This review begins with 2 updates in preoperative medicine in the vascular surgery population, including recent publications regarding the management of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and antiplatelet medications in the perioperative period. The next section focuses on complications related to thoracic endovascular aortic surgery, particularly as technology advances allow for endovascular repair of more complex anatomy. The final section focuses on quality in vascular surgery and evaluates recent publications that examine the safety and feasibility of fast-track endovascular aortic surgery. Even though this is only a sampling of the literature published in 2018 relevant to the cardiovascular anesthesiologist, these themes represent some of the topics most clinically relevant to the perioperative period.

Folding procedure to diminish type 3 endoleakage after open stent graft surgery with TEVAR extension

We herein report a new procedure to prevent type 3 endoleakage (EL3) after open stent graft (OSG) surgery with thoracic endovascular aortic repair (TEVAR) extension. The OSG Dacron graft portion is reversed and folded inside the OSG stent graft portion intraoperatively, filling the crack between the OSG and TEVAR device. We applied this procedure in two patients with no postoperative complications. Our folding procedure may prevent EL3 after OSG surgery if TEVAR extension is needed in the future.

Consistency of Proximal-to-Distal Tapering of Descending Thoracic Aortic Diameter: Quantification Using a Novel Computer Tomography-based Assessment

BACKGROUND

Successful endovascular repair of thoracic aorta for type B aortic dissection requires correct stent-graft sizing, particularly of distal landing zone which is mainly based on operator experience. The present study aimed to quantitatively define proximal-to-distal tapering of descending thoracic aortic diameter and its consistency.

METHODS

The novel parameter HDP (Hundred times Distance accounts for Percentage)-measured as distance from the distal end of the left subclavian artery to each level along the aortic central line/length from the distal end of the left subclavian artery to the proximal end of the celiac artery along the aortic central line × 100-was calculated per 1% unit of descending thoracic aorta based on 3-mensio software-derived measurements from 281 consecutive individuals who had undergone enhanced chest computer tomography scanning. Association between HDP and maximal diameter of descending thoracic aorta was assessed by using the generalized additive mixed model with smoothing function and threshold saturation effect analyses with generalized estimating equations. Nonadjusted and adjusted models were performed to illuminate its consistency.

RESULTS

Three inflection levels (HDPs of 15.01, 36.63, and 77.74) were identified which allowed to divide the descending thoracic aorta into 4 segments. The taper was consistent before and after adjusting for age, sex, height, body mass index, hypertension, smoking habits, hyperlipidemia, and diabetes. Although 1% unit of descending thoracic aorta decreases, the maximal diameter reduces to 0.007 mm (-0.025, 0.010; P = 0.414) in the segment with HDP <15.01, to 0.151 mm (-0.158, -0.145; P < 0.001) in the segment with 15.01 ≤ HDP < 36.63, to 0.038 mm (-0.040, -0.036; P < 0.001) in the segment with 36.63 < HDP ≤ 77.74; and to 0.026 mm (-0.049, -0.002; P = 0.035) in the segment with HDP > 77.74, respectively.

CONCLUSIONS

The maximal diameter of descending thoracic aorta decreases gradually and consistently among individuals free of aortic diseases.

How does descending aorta geometry change when it dissects?

OBJECTIVES

Thoracic endovascular aortic repair is the treatment of choice in complicated acute type B aortic dissection. How to infer predissection aortic diameter is not well understood. Our aim was to delineate changes in descending aortic geometry due to dissection.

METHODS

Five tertiary centres reviewed their acute aortic dissection type B databases containing 802 patients. All patients who had undergone computed tomography angiography less than 2 years before and immediately after aortic dissection onset were included. We compared the aortic geometry before and after the dissection onset.

RESULTS

Altogether 25 patients were included [median age 60 (first quartile 52, third quartile 72) years; 60% men]. In all except 1 patient, the maximum descending aortic diameter was less than 45 mm before aortic dissection onset. The largest increase in diameter induced by the dissection was observed in the proximal descending aorta 28.2 (25.1, 32.1) vs 34.6 (31.3, 39.1) mm (+6.4 mm; +23%; P < 0.001). The thoracic descending aortic length increased after the dissection onset [253.3 (229.3, 271.9) vs 261.3 (247.9, 285.4) mm; P = 0.003]. The predissection aortic diameter of the proximal thoracic descending aorta was 7.9 (5.2, 10.7) mm larger (P < 0.001) than the post-dissection area-derived true-lumen diameter and 2.5 (1.3, 6.1) mm larger than the maximum true-lumen diameter (P < 0.001).

CONCLUSIONS

Type B aortic dissection increases the diameter, length and volume of the descending thoracic aorta. The predissection aortic diameter most closely resembles the post-dissection maximum diameter of the true lumen.

Thoracic Endovascular Aortic Repair for Acute Aortic Dissection

Thoracic endovascular aortic repair (TEVAR) for thoracic aortic disease constitutes a paradigm shift in the treatment strategy of aortic dissection, as well as thoracic aortic aneurysms. Conventionally, most patients with Stanford type B acute aortic dissection are treated using conservative medical treatment during the acute phase. However, in patients with complicated type B aortic dissection who present with life-threatening complications, TEVAR has been introduced as a novel and less-invasive alternative and has shown better early results than those observed with conventional therapy. Recently, TEVAR was reported to be effective in not only promoting thrombosis of the false lumen but also in preventing aortic enlargement observed at long-term follow-up. TEVAR has been established as first-line therapy for complicated type B aortic dissection. In contrast, a considerable number of patients who received acute phase medical treatment required surgical intervention for chronic dissecting aortic aneurysms. With the increasing popularity of TEVAR for the treatment of complicated type B aortic dissection, prophylactic and pre-emptive TEVAR has been considered in patients with uncomplicated type B aortic dissection. However, supportive evidence for this strategy is limited, and reassessment is mandatory because it is continuously evolving. Although acute type A aortic dissection is a life-threatening condition, the results of open surgery continue to improve in the modern surgical era. Open surgical treatment is well established and recognized as a gold standard even in the endovascular era. Presently, the application of TEVAR for ascending aortic dissection has undergone a change, and TEVAR is considered a viable rescue option for patients with type A aortic dissection who are not eligible for open surgical repair. However, TEVAR for the descending aorta is well-established treatment for retrograde type A dissection. Several conceptual and technical issues remain unresolved, and technological advances would lead to the development of innovative disease-specific devices and solutions in the future for endovascular treatment of acute aortic dissection. (This is a translation of Jpn J Vasc Surg 2018; 27: 337–345.)

Advantages of Transesophageal Echocardiography during Stent Grafting for Aortic Dissection: A Report of Three Cases

We report the cases of three patients who underwent thoracic endovascular aortic repair for type B aortic dissection in which transesophageal echocardiography (TEE) was used to guide the procedure in addition to fluoroscopy. TEE was found to be advantageous because it can visualize vascular structures along with the guidewire and devices. Furthermore, it provides real-time hemodynamic and hematological information without the need for contrast injection or radiation exposure. Although TEE assessment requires expertise, the efficient use of TEE appears to be helpful for further improving the outcomes of endovascular surgery for aortic dissection.

Virtual stenting with simplex mesh and mechanical contact analysis for real-time planning of thoracic endovascular aortic repair

In aortic endovascular repair, the prediction of stented vessel remodeling informs treatment plans and risk evaluation; however, there are no highly accurate and efficient methods to quantitatively simulate stented vessels. This study developed a fast virtual stenting algorithm to simulate stent-induced aortic remodeling to assist in real-time thoracic endovascular aortic repair planning.

Methods: The virtual stenting algorithm was established based on simplex deformable mesh and mechanical contact analysis. The key parameters of the mechanical contact analysis were derived from mechanical tests on aortic tissue (n=40) and commonly used stent-grafts (n=6). Genetic algorithm was applied to select weighting parameters. Testing and validation of the algorithm were performed using pre- and post-treatment computed tomography angiography datasets of type-B aortic dissection cases (n=66).

Results: The algorithm was efficient in simulating stent-induced aortic deformation (mean computing time on a single processor: 13.78±2.80s) and accurate at the morphological (curvature difference: 1.57±0.57%; cross-sectional area difference: 4.11±0.85%) and hemodynamic (similarity of wall shear stress-derived parameters: 90.16-90.94%) levels. Stent-induced wall deformation was higher (p<0.05) in distal stent-induced new entry cases than in successfully treated cases, and this deformation did not differ significantly among the different stent groups. Additionally, the high stent-induced wall deformation regions and the new-entry sites overlapped, indicating the usefulness of wall deformation to evaluate the risks of device-induced complications.

Conclusion: The novel algorithm provided fast real-time and accurate predictions of stent-graft deployment with luminal deformation tracking, thereby potentially informing individualized stenting planning and improving endovascular aortic repair outcomes. Large, multicenter studies are warranted to extend the algorithm validation and determine stress-induced wall deformation cutoff values for the risk stratification of particular complications.

Stent Graft-Induced Pseudoaneurysms in a Patient With Vasculo-Behçet Disease

Behçet disease (BD) is a rare condition that causes pathologic abnormalities in multiple systems, with vascular complications, termed vasculo-BD, occurring in 7% to 29% of individuals with the disease. Arterial complications portend the highest mortality in vasculo-BD. Here, we present a case of a young woman with active vasculo-BD in whom endovascular repair failed, with development of stent graft-induced pseudoaneurysms at the proximal and distal extents of the stent graft, necessitating open descending thoracic aortic repair.

Endovascular repair of type B aortic dissection with the restrictive bare stent technique: morphologic changes, technique details, and outcomes

Purpose

The aim of this study was to present our experience and assess the morphologic changes of the descending aorta after the restrictive bare stent (RBS) technique in the treatment of type B aortic dissection (TBAD).

Patients and methods

A retrospective study was conducted of 22 consecutive patients with TBAD who underwent RBS treatment between February 2012 and June 2016. Indications for the RBS procedure included radiological evidence of true lumen (TL) compression or collapse and/or tortuosity index (TI) of the descending aorta >1.4. Technique success, descending aorta morphology, and clinical outcomes were evaluated.

Results

The technical success rate was 100%. Patients treated with the RBS technique were often accompanied by TL collapse (45.5%) or TI >1.4 (59.1%). One-month postoperative computed tomography angiography showed that the taper ratio, oversizing ratio of the stent graft, and TI values were significantly decreased compared with preoperative computed tomography angiography values (P<0.05). The 30-day mortality rate was 0%. In total 95.2% had a thrombosed false lumen in the segment of aortic coverage, and TL diameters were increased in 40.3%±11% (mean ± SD) and 37.5%±17.9% of patients in the thoracic and abdominal segments, respectively. During the follow-up from 16 to 64 months (33±19 months), no distal stent graft-induced new entry, endoleak, and paraplegia were observed. One patient died from rupture of a chronic TBAD with aneurysm degeneration.

Conclusion

Mid-term outcomes showed RBS to be a flexible and feasible approach to repair TBAD. RBS corrects the descending aorta morphology and promotes TL expansion in most patients, but the rupture of chronic TBAD with aneurysm degeneration was not prevented in all patients.

High Wall Stress May Predict the Formation of Stent-Graft-Induced New Entries After Thoracic Endovascular Aortic Repair

PURPOSE

To explore the potential role of morphological factors and wall stress in the formation of stent-graft-induced new entries (SINE) based on computed tomography (CT) images after thoracic endovascular aortic repair (TEVAR).

CASE REPORT

Two female patients aged 59 years (patient 1) and 44 years (patient 2) underwent TEVAR for type B dissection in the chronic (patient 1) or subacute (patient 2) phase. CT scans at 3-month follow-up showed varying degrees of false lumen thrombosis in both patients. At 14-month follow-up, a SINE was observed in patient 1 while the dissected aorta in the other patient remained stable. Morphological and finite element analyses were performed based on the first follow-up CT images. The computational results showed that the SINE patient had higher stent-graft tortuosity than the non-SINE patient and much higher wall stress in the region close to the distal SINE.

CONCLUSION

This case study suggests that high stent-graft tortuosity can lead to high wall stress, which is potentially linked to the formation of SINE. Further large population-based studies are needed to confirm this preliminary finding.

Physician-Modified Thoracic Stent-Graft With Low Distal Radial Force to Prevent Distal Stent-Graft–Induced New Entry Tears in Patients With Genetic Aortic Syndromes and Aortic Dissection

Purpose: To describe a novel modification technique to lower the distal radial force of a thoracic stent-graft so as to avert stent-graft–induced new entry tears (SINE) in the fragile aorta of patients with genetic aortic disease and aortic dissection. Technique: A commercially available thoracic stent-graft is partially deployed on a back table. The most distal Z-stent is removed, the distal fabric is marked by vascular clips, and the modified stent-graft is reloaded and deployed in the true lumen of an aortic dissection. The technique is demonstrated in 3 patients with aortic dissection related to genetic aortic diseases. Conclusion: Creating a low distal radial force stent-graft is easy and can be done in a short time. Endovascular implantation appears feasible and safe.

Incidence and risk factors for retrograde type A dissection and stent graft-induced new entry after thoracic endovascular aortic repair

OBJECTIVE

Stent graft (SG)-induced new entry (SINE) and retrograde type A dissection (RTAD) are serious device-related complications occurring after thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection (TBAD) and may lead to endograft-related complications including retrograde dissection and death. The purpose of this study was to investigate the incidence and risk factors for the development of RTAD and SINE after TEVAR for TBAD and to identify the complications associated with this.

METHODS

From April 2005 to October 2013, there were 997 patients who underwent TEVAR for TBAD; 852 were followed up (0-6 years; mean, 2.6 years), and 59 SINEs developed in 53 patients. The oversizing ratio and incidence of RTAD and SINE were compared between proximal bare stent (PBS) and non-PBS groups and RTAD and SINE and non-RTAD and non-SINE groups. The baseline characteristics and SG configurational factors potentially affecting both RTAD and distal SINE were analyzed.

RESULTS

There was no significant difference between PBS and non-PBS groups in the incidence of RTAD. A greater oversizing ratio was related to a higher distal SINE rate. SINE was seen more frequently in smokers and in patients with hypertension, Marfan syndrome, and TEVAR in the chronic phase and less frequently in complicated dissection cases. Device-related factors for SINE were SG with a connecting bar and SG length <165 mm. The SG length <165 mm increased the overall proximal and distal SINE incidence in multivariate analysis.

CONCLUSIONS

The presence of a PBS is not associated with a higher RTAD rate, whereas the use of an SG with a connecting bar and length <165 mm increases the risk of RTAD and SINE after TEVAR.