Coil embolization of persistent false lumen after stent graft repair of type B aortic dissection

The Caged Knickerbocker: A Novel Modification to Targeted False Lumen Management in Complex Aortic Dissection

INTRODUCTION

Targeted false lumen management has been described for complex presentations of aortic dissection. The "Knickerbocker" technique is often referenced and includes dilating a focal portion of an oversized endograft in the true lumen to purposefully rupture the false lumen septum, but at the expense of increased risk for visceral propagation and malperfusion. This case series describes a novel modification of the Knickerbocker technique by caging the distal end of the endograft prior to focal dilation.

METHODS

A retrospective chart review was conducted at a tertiary academic center from 2018-2020. Patients were included if they had a history or current presentation of aortic dissection and underwent a Caged Knickerbocker (CKB) repair. Data were collected to include demographics, indications for repair, technical success, perioperative outcomes, hospital course, mortality, and further aortic interventions.

RESULTS

Five patients were included in our evaluation. Four patients (80%) presented with chronic Type B aortic dissection (cTBAD) and concomitant aneurysmal degeneration of the thoracic aorta; 1 patient (20%) presented with an acute rupture secondary to cTBAD. Three patients (60%) had previous aortic repairs, 2 of which were for Type A Aortic Dissection that additionally required redo sternotomy and total arch replacement prior to CKB. CKB was technically successful in all cases with no peri-operative complications. Two (40%) patients required further aortic intervention due to aneurysmal degeneration.

CONCLUSION

Achieving complete false lumen thrombosis is a considerable challenge when managing complex aortic dissections. Our data demonstrate the technical feasibly and early successful outcomes with the CKB approach. Importantly, CKB facilitates future distal extension into the para-visceral aorta in cases of complex thoracoabdominal aortic aneurysms. Further research should focus on discerning individual patients who will benefit from targeted false lumen management and compare outcomes between different approaches.

Managing False Lumen Patency in Chronic Thoracic Aortic Dissecting Aneurysms With Coil Embolization

Thoracic endovascular aortic repair has become the preferred modality of treatment of complicated type B aortic dissections. However, persistent pressurization of the false lumen can lead to negative aortic remodeling with aneurysmal dilation. Described herein is the coil embolization technique that can be used to manage this complication and a review of the literature on the recent development of management options.

Methods and outcomes of endovascular false lumen embolization for thoracic aortic dissection

PURPOSE

To provide a contemporary review on endovascular false lumen (FL) embolization for thoracic aortic dissection (AD) and evaluate its early outcome.

METHODS

A systematic literature review on FL embolization for thoracic AD from January 2003 to December 2020 was performed under the instruction of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. Each article was analyzed using a standardized protocol including predefined demographic characteristics, perioperative mortality and major complications.

RESULTS

A total of 29 papers with 229 patients were included into the analysis. The methods of FL occlusion used were: the Candy-Plug technique, the knickerbocker technique, the "cork in the bottleneck" technique and direct FL embolization with combination of stent-grafts, coils, onyx, plugs and glue. FL embolization procedure was performed in 79 patients (34.5%) with type A AD and 150 (65.5%) with type B AD. FL direct embolization was the most frequently used technique, and it was applied in 198 (86.5%) patients. Candy-plug, knickerbocker and "cork in the bottleneck" techniques were used in 26 (11.4%), 3 (1.3%) and 2 (0.9%) patients, respectively. Technical success was achieved in all patients except one (228/229, 99.6%) in which implantation of a stent to celiac trunk was not possible. There were four hospital deaths (1.7%). Neurological complications occurred in 6 patients (2.6%), including 4 (1.7%) spinal cord ischemia and 2 (0.9%) ischemic stroke. There were 1 (0.4%) iatrogenic retrograde dissection and 2 (0.9%) renal failure reported. The mean duration of follow-up was 16.5 months. There were 21 deaths (9.3%) during follow-up, and 8 (3.6%) were aorta-related. Thirty-three (14.7%) secondary intervention were performed. Five patients (2.2%) required open completion thoracoabdominal procedure incorporating the stent-graft into the repair. Complete FL thrombosis was observed in 181 (80.4%) patients, 34 (15.1%) had partial thrombosis, and 10 (4.4%) had FL progression.

CONCLUSIONS

FL embolization of the distal thoracic aorta is a promising technique in a group of patients to promote FL thrombosis and aortic remodeling in thoracic aorta.

False lumen embolization as a rescue technique in the setting of acute and chronic dissecting aneurysms as adjunct to thoracic endovascular aortic repair

Complicated type B aortic dissection (TBAD) is a life-threatening condition requiring surgical intervention. One such complication in the acute or chronic setting is aneurysmal degeneration. The dissected aortic wall is weakened, and the pressures in the false lumen are often high. In the past decade, thoracic endovascular aortic repair (TEVAR) has become the treatment of choice for TBAD. TEVAR can be complicated by lack of false lumen thrombosis, increasing the risk of death. We present three cases of TBAD with patent false lumens after TEVAR that were treated by false lumen coil embolization.

Development of a shear-thinning biomaterial as an endovascular embolic agent for the treatment of type B aortic dissection

False lumen embolisation is a promising treatment strategy in type B aortic dissection (TBAD) but it is limited by the lack of a disease-specific embolic agent. Our aim was to develop a biomaterial that could be delivered minimally-invasively into the TBAD false lumen and embolise the region. We created 24 shear-thinning biomaterials from blends of gelatin, silicate nanoparticles and silk fibroin, and evaluated their suitability as a false lumen embolic agent in TBAD. We determined the stability of mechanical properties by measuring the compressive modulus of samples stored in physiological conditions over a 21 day period. We quantified injectability by measuring the force required to inject each biomaterial through catheters of varying diameter. We also assessed in vitro degradation rates by measuring weight change over 30 days. Finally, we developed an in vitro experimental pulsatile flow setup with two different anatomically-correct TBAD geometries and performed 78 false lumen occlusion experiments under different operating conditions. We found that the compressive moduli changed rapidly on exposure to 37 °C before stabilising by Day 7. A high silicate nanoparticle to gelatin ratio resulted in greater compressive moduli, with a maximum of 117.6 ± 15.2 kPa. By reducing the total solid concentration, we could improve injectability and biomaterials with 8% (w/v) solids required <80 N force to be injected through a 4.0 mm catheter. Our in vitro degradation rates showed that the biomaterial only degraded by 1.5-8.4% over a 30 day period. We found that the biomaterial could occlude flow to the false lumen in 99% of experiments. In conclusion, blends with high silicate nanoparticle and low silk fibroin content warrant further investigation for their potential as false lumen embolic agents and could be a promising alternative to current TBAD repair methods.

Staged coil embolization after thoracic endovascular stent grafting for aneurysmal chronic type B aortic dissection: A case report

We herein describe a 38-year-old woman with Marfan syndrome and chronic type A aortic dissection. Computed tomography showed that the sinus of Valsalva and thoracoabdominal aorta had a diameter of 62 and 55 mm, respectively. After 7 months of a Bentall operation and total arch replacement with the elephant trunk technique, we performed thoracic endovascular aortic repair for an aneurysm of the descending aorta, but we preserved the retrograde flow into the false lumen because it supplied vessels perfusing the spinal cord. Computed tomography angiography 14 months after thoracic endovascular aortic repair showed that the thoracic aortic diameter had increased to 68 mm. We then performed partial (proximal only) coil embolization of the false lumen. After 6 months, the thoracic aortic diameter had decreased to 60 mm and the spinal cord remained perfused via the distal false lumen. Staged coil embolization after thoracic endovascular aortic repair for aneurysmal chronic type B aortic dissection is feasible and can be beneficial.

Treatment of Type I Endoleak after Thoracic Endovascular Aortic Repair and Stent Extension via False Lumen Catheterization and Coil Embolization

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive alternative to conventional open surgical reconstruction for the treatment of thoracic aortic dissection. However, the possibility of a type I endoleak may contribute to false lumen enlargement and rupture. Here, we present a case of successful treatment of type I endoleak after TEVAR and endograft extension for a complicated descending thoracic aortic dissection that was embolized by coils via a false lumen channel through the distal entry tear. This endovascular technology might offer a new option to treat thoracic type I endoleak by embolizing the blood entry site of the endoleak through the distal entry site and false lumen.

Influence of distal entry tears in acute type B aortic dissection after thoracic endovascular aortic repair

OBJECTIVE

This study evaluated the clinical influence of distal entry tears in acute type B aortic dissection (ATBAD) after thoracic endovascular aortic repair (TEVAR).

METHODS

From August 2009 to December 2014, the clinical outcomes of 130 patients who underwent TEVAR for ATBAD were retrospectively analyzed. According to whether distal entry tears existed after TEVAR, patients were divided into group A (n = 25, absence of distal entry tears) and group B (n = 105, presence of distal entry tears). We evaluated clinical outcomes, including mortality and morbidity in early and late follow-up, as well as aortic remolding. Late aortic events were defined as aortic dissection-related events occurring >30 days from the initial TEVAR procedures, which consisted of endoleak, retrograde type A aortic dissection, aortic enlargement, late rupture, repeat dissection, and stent-induced new entry tear.

RESULTS

The study comprised 130 patients (114 men [87.7%] and 16 women [12.3%)] with a mean age of 53.71 years. The 30-day mortality was 3.1%, and early morbidity included type I endoleak, 3.1%, organ failure, 3.8%; stroke, 3.1%; spinal cord ischemia, 0%; and early rupture 1.5%. The overall survival rate by Kaplan-Meier analysis at 1, 3, and 5 years was 93.8%, 89.5%, and 79.2%, respectively. There were no significant differences in early morbidity and 30-day mortality and late survival between group A and group B. However, group A had a significantly lower rate of late aortic events than group B (P = .028 by log-rank test). Meanwhile, group A had better aortic remolding than group B in complete thrombosis of the thoracic aorta at 12 months postoperatively (100% vs 83.5%; P = .029).

CONCLUSIONS

This study demonstrated that TEVAR for ATBAD had low perioperative morbidity and mortality and satisfactory midterm outcome. Distal entry tears increase the occurrence of late aortic events and inhibit aortic remolding but do not have a significantly negative effect on late survival. Repairing all entry tears to restore single-lumen blood flow and enhance false lumen thrombosis might benefit selected patients.

Persistent Intraluminal Pressure After Endovascular Stent Grafting for Type B Aortic Dissection

OBJECTIVES

Despite technically successful thoracic endovascular stent graft repair (TEVAR) in patients with Stanford Type B aortic dissection (TBAD), long-term follow up studies have shown that the false lumen may continue to dilate. The aim of this study was to analyze the possible mechanisms leading to such changes from a hemodynamic perspective.

METHODS

Twenty-eight ex vivo fresh porcine TBAD models (Mo A: 10; Model B: 12; Model C: 6) were established to simulate three clinical situations: Model A with patent false lumen (pre-TEVAR); Model B with distal re-entry only (post-TEVAR), and Model C with thrombus filling in the false lumen and a distal re-entry (chronic stage of post-TEVAR). Synchronous pressure waveforms were taken from both the true and the false lumen. True lumen and false lumen pressure differences were calculated for each model as four indices: systolic index (SI), diastolic index (DI), mean pressure index (MPI) and area under curve index (AUCI). These indices were compared between the three models.

RESULTS

False lumen pressure and corresponding pressure-accumulating effects were significantly higher in Model A than in Model C: SI (99.9% vs. 189.4%; p < .001); MPI and AUCI (99.5% vs. 128.2%; 99.5% vs. 128%; p < .001). The SI, MPI, and AUCI were significantly higher in Model B compared with Model C. The differences between the four indices were not significant between Model A and B. The false lumen area under curve (AUC) in Model C was merely lowered by 20% compared with its true lumen (67.5 mmHg vs. 85.2 mmHg).

CONCLUSION

The false lumen pressure remained unchanged in the non-thrombosed segment with patent blood flow after the primary entry tear sealed. Intraluminal pressure reduction in the thrombosed false lumen was significant. However, nearly 80% of the pressure remained in the thrombosed false lumen. If this high intra-thrombus pressure persists, it may contribute to delayed aneurysmal formation after endovascular treatment.

Biomechanical Changes After Thoracic Endovascular Aortic Repair in Type B Dissection

Thoracic endovascular aortic repair (TEVAR) has evolved into an established treatment option for type B aortic dissection (TBAD) since it was first introduced 2 decades ago. Morbidity and mortality have decreased due to the minimally invasive character of TEVAR, with adequate stabilization of the dissection, restoration of true lumen perfusion, and subsequent positive aortic remodeling. However, several studies have reported severe setbacks of this technique. Indeed, little is known about the biomechanical behavior of implanted thoracic stent-grafts and the impact on the vascular system. This study sought to systematically review the performance and behavior of implanted thoracic stent-grafts and related biomechanical aortic changes in TBAD patients in order to update current knowledge and future perspectives.

Scheduled re-entry coil embolization before entry coverage of thoracic endovascular stent grafting for aneurysmal chronic type B aortic dissection

Endovascular treatment for type B dissections is controversial. This therapy aims at complete occlusion and thrombosis of the false lumen of the aneurysm. We report a case where cessation of flow was achieved using covered stent grafts in conjunction with coil embolization of the false lumen. The use of scheduled coil re-entry embolization of the false lumen before endovascular entry coverage using a stent graft is a novel approach that could become a treatment option for aneurysmal type B dissection.