The Knickerbocker Technique: Technical Aspects and Single-Center Results of a New Endovascular Method for False Lumen Occlusion in Chronic Aortic Dissection

Emerging Trends in the Care of Type B Aortic Dissections

Aortic dissection is the most common of the acute aortic syndromes. Acute aortic dissection remains a highly morbid and potentially lethal condition despite contemporary advances in medical and surgical care. Type B aortic dissection (TBAD) is classified as uncomplicated, uncomplicated with high-risk features, and complicated. The role of thoracic endovascular aortic repair (TEVAR) in uncomplicated TBAD remains uncertain and is the topic of ongoing clinical trials. In most complicated cases, TEVAR is effective at restoring visceral and extremity blood flow. TEVAR has also been shown to arrest hemorrhage in the setting of thoracic aortic rupture. TEVAR has been demonstrated to induce satisfactory remodeling in the covered segment of the thoracic aorta, but progressive enlargement of the visceral aorta has led to a variety of techniques designed to promote remodeling in the uncovered aortic segment. There is a need to better define high-risk features so that treatment can be tailored to specific clinical conditions.

Post-dissection Thoraco-abdominal Aortic Aneurysm Managed by Fenestrated or Branched Endovascular Aortic Repair

OBJECTIVE

Fenestrated or branched endovascular aortic repair (F/B-EVAR) is a valuable treatment in patients with chronic post-dissection thoraco-abdominal aneurysm (PD-TAAA). This study aimed to analyse early and follow up outcomes of F/B-EVAR in these patients.

METHODS

Thirty day and follow up outcomes of consecutive patients with PD-TAAA treated with F/B-EVAR in a tertiary centre over eight years were analysed retrospectively. All patients presenting with PD-TAAA and managed with F/B-EVAR were eligible. A modified Crawford's classification system was used. Thirty day mortality and major adverse event (MAE) rates were analysed. Time to event data were estimated with Kaplan-Meier survival analysis.

RESULTS

Fifty five patients (80% men, mean age 63.7 ± 7.7 years) were included: 12 (22%) were managed urgently; 25 (46%) for chronic type B aortic dissection; and the remainder for residual type A aortic dissection. Of these patients, 88% had undergone previous thoracic endovascular aortic repair. Prophylactic cerebrospinal fluid drainage (CSFD) was used in 91%. Fifteen (27%) patients were treated with F-EVAR, nine (16%) with fenestrations and branches, and 31 (56%) with B-EVAR. False lumen adjunctive procedures were used in 56%. Technical success was achieved in 96% of patients. The thirty day mortality rate was 7% and MAE rate was 20%. Spinal cord injury (SCI) grades 1 - 3 and grade 3 rates were 13% and 2%, respectively. Mean follow up was 33.0 ± 18.4 months. Survival and freedom from unscheduled re-intervention were 86% (standard error [SE] 5%) and 55% (SE 8%) at 24 months, respectively. Freedom from target vessel stenosis and occlusion was higher in F-EVAR at the 12 month follow up (p = .006) compared with B-EVAR.

CONCLUSION

Fenestrated or branched endovascular repairs in patients with PD-TAAA showed high technical success, with acceptable early mortality and MAE rates. The SCI rate was > 10%, despite CSFD use and staged procedures. Almost a half of patients needed an unscheduled re-intervention within 24 months after F/B-EVAR.

Initial Single-Center Experience With the Knickerbocker Technique During Thoracic Endovascular Aortic Repair to Block Retrograde False Lumen Flow in Patients With Type B Aortic Dissection

OBJECTIVE

Effectiveness of thoracic endovascular aortic repair in type B aortic dissection is impaired by persistent retrograde false lumen flow via distal re-entry tears. Controlled, stentgraft-assisted balloon dilatation of the true lumen at its lower end, or Knickerbocker technique, may block retrograde false lumen flow and consequently improve effectiveness by inducing immediate thrombosis along the entire descending thoracic aorta.

MATERIALS AND METHODS

A single-center retrospective analysis was performed for all consecutive patients with aortic dissection treated with the Knickerbocker technique to block retrograde false lumen flow.

RESULTS

Eleven patients were included for analysis. Intraoperative control angiography showed successful occlusion of the false lumen at the level of balloon dilatation in 9 out of 11 patients (82%). There was one perioperative mortality (9%), due to stroke. There were 2 early reinterventions, due to retroperitoneal bleeding and due to chyle leakage in the neck after left subclavian artery bypass. Median clinical follow-up duration was 6 (interquartile range [IQR] 2-11] months. There were 2 deaths during follow-up, one at 2 months after TEVAR from unknown cause of death, and one after 11 months due to rupture of an ascending aortic pseudoaneurysm. The Knickerbocker technique led to positive aortic remodeling. At 3 months follow-up, 100% of patients showed complete false lumen thrombosis in the thoracic aorta proximal to the level of balloon dilatation, with decreasing false lumen diameters (100%) and stable (44%) or decreasing (56%) total aortic diameters. In most patients, the false lumen distal to the stentgraft (i.e. at visceral level) remained patent (11% false lumen thrombosis rate), leading to ≥2 mm dilatation at this level (78% of patients) and in the infrarenal abdominal aorta (56% of patients) at 3 months postoperatively. No distal stent-graft-induced new entry tears were noticed during follow-up.

CONCLUSION

The Knickerbocker technique is feasible and effective, leading to positive aortic remodeling of the aorta covered by stentgraft in all of a small cohort of patients.

CLINICAL IMPACT

Persistent, retrograde false lumen perfusion from distal re-entries following thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection, may lead to progressive, aneurysmal dilatation. Controlled, stent graft-assisted balloon dilatation of the true lumen in the distal descending aorta (i.e. Knickerbocker technique) during TEVAR effectively excludes the false lumen from persistent flow resulting in positive aortic remodeling in our small cohort of patients, and hence potentially eliminates the risk of late post-dissection aneurysm formation in the descending thoracic aorta.

Design, evolution, and experience with the candy plug device for endovascular false lumen occlusion of chronic aortic dissections

INTRODUCTION

The management of the false lumen (FL) when dealing with aortic dissection is a crucial aspect since inducing its thrombosis is necessary in order to achieve aortic remodeling. One of the pitfalls of endovascular treatment of aortic dissection (AD) is retrograde distal FL perfusion and pressurization, which prevents FL thrombosis and thus aortic remodeling, while being associated with aneurysmal degeneration of the FL and poor long-term outcomes.

AREAS COVERED

Currently, there is no CE/FDA approved device for FL closure, however different techniques and devices have been proposed to overcome this challenge, the most known of which is the Candy Plug (CP). This review aims to describe the CP device, its implantation technique, and the available data in the literature (PubMed, Cochrane, and EMBASE databases; last queried, December 31, 2023).

EXPERT OPINIONS

While the treatment of AD remains technically challenging, the use of the CP technique to close any distal FL reperfusion proved to be feasible and safe with excellent rates of both technical and clinical success. Furthermore, recent studies have shown a quick learning curve with this technique.

Preemptive treatment in the acute and early subacute phase of uncomplicated type B aortic dissections with poor prognosis factors

Objective

Due to its favorable outcome regarding late morbidity and mortality, thoracic endovascular repair (TEVAR) is becoming more popular for uncomplicated type B aortic dissection (TBAD). This study aimed to compare preemptive endovascular treatment and optimal medical treatment (OMT) and OMT alone in patients presenting uncomplicated TBAD with predictors of aortic progression.

Design

Retrospective multicenter study.

Methods

We analyzed patients with uncomplicated TBAD and risk factors of progression in two French academic centers. Aortic events [defined as aortic-related (re)intervention or aortic-related death after initial hospitalization], postoperative complications, non-aortic events, and radiologic aortic progression and remodeling were recorded and analyzed. Analysis was performed on an intention-to-treat basis.

Results

Between 2011 and 2021, preemptive endovascular procedures at the acute and early subacute phase (<30 days) were performed on 24 patients (group 1) and OMT alone on 26 patients (group 2). With a mean follow-up of 38.08 ± 24.53 months, aortic events occurred in 20.83% of patients from group 1 and 61.54% of patients from group 2 (p < .001). No patient presented aortic-related death during follow-up. There were no differences in postoperative events (p = 1.00) and non-aortic events (p = 1.00). OMT patients had significantly more aneurysmal progression of the thoracic aorta (p < .001) and maximal aortic diameter (p < .001). Aortic remodeling was found in 91.67% of patients in group 1 and 42.31% of patients in group 2 (p < .001). A subgroup analysis of patients in group 1 showed that patients treated with preemptive TEVAR and STABILISE had reduced maximum aortic diameters at the 1-year (p = .010) and last follow-up (p = .030) compared to those in patients treated with preemptive TEVAR alone.

Conclusion

Preemptive treatment of uncomplicated TBAD with risk factors of progression reduces the risk of long-term aortic events. Over 60% of medically treated patients will require intervention during follow-up, with no benefit in terms of postoperative events. Even after surgical treatment, patients in the OMT group had significantly more aneurysmal progression, along with poorer aortic remodeling.

Pre-emptive False Lumen Embolization to Prevent Persistent Type II Endoleak in Fenestrated-Branched Endovascular Repair of Post-Dissection Thoracoabdominal Aortic Aneurysms

PURPOSE

The purpose was to describe a technique to promote false lumen (FL) thrombosis in post-dissection thoracoabdominal aortic aneurysms (PD-TAAAs) managed by fenestrated/branched endografting (F/B-EVAR).

TECHNIQUE

A 5/6Fr-90 cm length sheath is advanced from the true lumen (TL) to FL through the most distal entry tear of the infrarenal aorta or iliac arteries. It is parked in the most cranial portion of the FL in the thoracic aorta. Aortic endografts are deployed in the TL excluding all the para-visceral/distal entry tears and target visceral vessels bridging stenting is performed. A selective FL angiography is performed through the 5/6Fr sheath to detect the origin of all segmentary arteries. Embolization of FL is performed from above to below by M-reye pushable coils, obtaining the packaging of FL. After completion angiography, the 5/6Fr sheath is retrieved in external iliac artery and molding ballooning of the distal segment of the aortic/iliac endograft is performed. Between 2019 and 2023, this technique was applied in 11cases with a median number of 73 (interquartile range [IQR=12) coils. Out of 8 (72%) patients with available radiological follow-up at 1 year, 7 exhibited complete FL thrombosis.

CONCLUSIONS

The FL coiling in PD-TAAAs managed by F/B-EVAR is feasible, safe, and effective to promote the complete FL thrombosis.

CLINICAL IMPACT

Preemptive false lumen embolization is a feasible, safe, and effective technique for preventing persistent type II endoleaks after fenestrated-branched endovascular repair of post-dissection thoracoabdominal aortic aneurysms. This technique may be routinely recommended to promote FL thrombosis and aortic remodeling after FB-EVAR in PD-TAAAs, thereby reducing the incidence of reinterventions during follow-up.

Transcatheter electrosurgical septotomy technique for chronic postdissection aortic aneurysms

Aortic dissection often results in chronic aneurysmal degeneration due to progressive false lumen expansion. Thoracic endovascular aortic repair and other techniques of vessel incorporation such as fenestrated-branched or parallel grafts have been increasingly used to treat chronic postdissection aneurysms. True lumen compression or a vessel origin from the false lumen can present considerable technical challenges. In these cases, the limited true lumen space can result in inadequate stent graft expansion or restrict the ability to reposition the device or manipulate catheters. Reentrance techniques can be used selectively to assist with target vessel catheterization. Transcatheter electrosurgical septotomy is a novel technique that has evolved from the cardiology experience with transseptal or transcatheter aortic valve procedures. This technique has been applied in select patients with chronic dissection to create a proximal or distal landing zone, disrupt the septum in patients with an excessively compressed true lumen, or connect the true and false lumen in patients with vessels that have separate origins. In the present report, we summarize the indications and technical pitfalls of transcatheter electrosurgical septotomy in patients treated by endovascular repair for chronic postdissection aortic aneurysms.

Visceral Aorta Electrocautery Septotomy to Allow Branched Endovascular Aortic Repair in Ruptured Chronic Post-Dissection Thoraco-Abdominal Aneurysm

PURPOSE

Endovascular repair of chronic post-dissection thoraco-abdominal aortic aneurysms (PD-TAAA) presents specific technical challenges due to the presence of chronic septum. Small true lumen diameter and false lumen visceral vessel origin can make branched endograft prohibitive. Septotomy may allow to overcome these challenges in cases of high complex anatomy.

TECHNIQUE

We describe the application of electrocautery septotomy to the visceral aorta segment to deploy an off-the-shelf branched endograft in a chronic PD-TAAA rupture with true lumen collapse.

CONCLUSIONS

Electrocautery septotomy can be an effective adjunctive technique to facilitate branched endograft, overcoming technical challenges associated with the endovascular treatment of chronic PD-TAAA.

CLINICAL IMPACT

Electrocautery septotomy is an adjunctive technique that can facilitate endovascular treatment of post-dissection thoraco-abdominal aneurysm. By creating a common lumen, this technique might reduce the number of re-interventions associated with PD-TAAA endovascular exclusion.

Reintervention of Residual Aortic Dissection after Type A Aortic Repair: Results of a Prospective Follow-Up at 5 Years

Background After a type A aortic dissection repair, a patent false lumen in the descending aorta is the most common situation encountered, and is a well-known risk factor for aortic growth, reinterventions and mortality. The aim of this study was to analyze the long-term results of residual aortic dissection (RAD) at a high-volume aortic center with prospective follow-up. Methods In this prospective single-center study, all patients operated for type A aortic dissection between January 2017 and December 2022 were included. Patients without postoperative computed tomography scans or during follow-up at our center, and patients without RAD were excluded. The primary endpoint was all-cause mortality during follow-up for patients with RAD. The secondary endpoints were perioperative mortality, rate of distal aneurysmal evolution, location of distal aneurysmal evolution, rate of distal reinterventions, outcomes of distal reinterventions, and aortic-related death during follow-up. Results In total, 200 survivors of RAD comprised the study group. After a mean follow-up of 27.2 months (1-66), eight patients (4.0%) died and 107 (53.5%) had an aneurysmal progression. The rate of distal reintervention was 19.5% (39/200), for malperfusion syndrome in seven cases (3.5%) and aneurysmal evolution in 32 cases (16.0%). Most reinterventions occurred during the first 2 years (82.1%). Twenty-seven patients were treated for an aneurysmal evolution of RAD including aortic arch with hybrid repair in 21 cases and branched aortic arch endoprosthesis in six cases. In the hybrid repair group, there was no death, and the rate of morbidity was 28.6% (6/21) (one minor stroke, one pulmonary complication, one recurrent paralysis with complete recovery and three major bleeding events). In the branched endograft group, there was no death, no stroke, and no paraplegia. There was one case (16.7%) of carotid dissection. Complete aortic remodeling or complete FL thrombosis on the thoracic aorta was found in 18 cases (85.7%) and in five cases (83.3%) in the hybrid and branched endograft groups, respectively. Conclusions: Despite a critical course in most cases of RAD, with a high rate of aneurysmal evolution and reintervention, the long-term mortality rate remains low with a close follow-up and a multidisciplinary management in an expert center.

Chronic Thoracic Aortic Dissection: How to Treat, When to Intervene

Thoracic aortic dissection (AD) is associated with increased morbidity and mortality. Acute aortic syndrome is the first presentation of the disease in most cases. While acute AD management follows concrete guidelines because of its urgent and life-threatening nature, chronic AD is usually overlooked, although it concerns a wide spectrum of patients surviving an acute event. Acute AD survivors ultimately enter a chronic aortic disease course. Patients with chronic thoracic AD (CTAD) require lifelong surveillance and a proportion of them may present with symptoms and late complications demanding further surgical or endovascular treatment. However, the available data concerning the management of CTAD is sparse in the literature. The management of patients with CTAD is challenging as far as determining the best medical therapy and deciding on intervention are concerned. Until recently, there were no guidelines or recommendations for imaging surveillance in patients with chronic AD. The diagnostic methods for imaging aortic diseases have been improved, while the data on new endovascular and surgical approaches has increased significantly. In this review, we summarize the current evidence in the diagnosis and management of CTAD and the latest recommendations for the surgical/endovascular aortic repair of CTAD.