Treatment of the Chronic Type B Aortic Dissection: The Pro-endovascular Argument

Staged hybrid repair for a patient with chronic type B aortic dissection

Vascular prosthesis replacement and thoracic endovascular repair (TEVAR) are used to treat patients with enlarged chronic type B aortic dissection. A case in which thrombosis of the false lumen was achieved by the staged combination of these two methods is presented. A 41-year-old woman with a thoracoabdominal aortic aneurysm (maximum short diameter 44 mm) identified 5 years earlier was being monitored as an outpatient in our department when she presented with back pain. Computed tomography (CT) showed acute type B aortic dissection (DeBakey type IIIa), which was managed conservatively. When CT showed an aortic dissection with a patent false lumen immediately below the left subclavian artery bifurcation, one-debranching TEVAR was performed to close the entry, along with right axillary artery to left axillary artery bypass surgery. Outpatient CT at 3 months postoperatively showed rapid enlargement in the vicinity of the celiac artery. Thoracoabdominal aortic replacement to prevent rupture was performed, and the patient was then monitored as an outpatient. CT at age 43 years showed enlargement of the residual false lumen. Additional TEVAR was successfully performed. Thus, three-stage treatment was conducted to enlarge the residual false lumen, causing successful thrombosis of the false lumen.

Cardiac Pulsatile Helical Deformation of the Thoracic Aorta Before and After Thoracic Endovascular Aortic Repair of Type B Dissections

PURPOSE

Type B aortic dissections propagate with either achiral (nonspiraling) or right-handed chiral (spiraling) morphology, have mobile dissection flaps, and are often treated with thoracic endovascular aortic repair (TEVAR). We aim to quantify cardiac-induced helical deformation of the true lumen of type B aortic dissections before and after TEVAR.

MATERIAL AND METHODS

Retrospective cardiac-gated computed tomography (CT) images before and after TEVAR of type B aortic dissections were used to construct systolic and diastolic 3-dimensional (3D) surface models, including true lumen, whole lumen (true+false lumens), and branch vessels. This was followed by extraction of true lumen helicity (helical angle, twist, and radius) and cross-sectional (area, circumference, and minor/major diameter ratio) metrics. Deformations between systole and diastole were quantified, and deformations between pre- and post-TEVAR were compared.

RESULTS

Eleven TEVAR patients (59.9±4.6 years) were included in this study. Pre-TEVAR, there were no significant cardiac-induced deformations of helical metrics; however, post-TEVAR, significant deformation was observed for the true lumen proximal angular position. Pre-TEVAR, cardiac-induced deformations of all cross-sectional metrics were significant; however, only area and circumference deformations remained significant post-TEVAR. There were no significant differences of pulsatile deformation from pre- to post-TEVAR. Variance of proximal angular position and cross-sectional circumference deformation decreased after TEVAR.

CONCLUSION

Pre-TEVAR, type B aortic dissections did not exhibit significant helical cardiac-induced deformation, indicating that the true and false lumens move in unison (do not move with respect to each other). Post-TEVAR, true lumens exhibited significant cardiac-induced deformation of proximal angular position, suggesting that exclusion of the false lumen leads to greater rotational deformations of the true lumen and lack of true lumen major/minor deformation post-TEVAR means that the endograft promotes static circularity. Population variance of deformations is muted after TEVAR, and dissection acuity influences pulsatile deformation while pre-TEVAR chirality does not.

CLINICAL IMPACT

Description of thoracic aortic dissection helical morphology and dynamics, and understanding the impact of thoracic endovascular aortic repair (TEVAR) on dissection helicity, are important for improving endovascular treatment. These findings provide nuance to the complex shape and motion of the true and false lumens, enabling clinicians to better stratify dissection disease. The impact of TEVAR on dissection helicity provides a description of how treatment alters morphology and motion, and may provide clues for treatment durability. Finally, the helical component to endograft deformation is important to form comprehensive boundary conditions for testing and developing new endovascular devices.

Surgical Strategy for Chronic Type B Dissecting Aortic Aneurysm to Prevent Aorta-Related Events

BACKGROUND

This study was aimed to evaluate the outcomes of performing open repair or thoracic endovascular aortic repair for chronic type B dissecting aortic aneurysm.

METHODS

From July 2004 to February 2019, 52 patients underwent surgery as open repair (n = 32) or endovascular repair (n = 20) for chronic type B dissecting aortic aneurysm. Replacement of the aorta was limited to the aneurysmal portion with or without reconstructing the visceral arteries or the segmental arteries. Stent grafts were deployed in the true lumen above the celiac artery to cover the primary entry for even DeBakey IIIb dissection.

RESULTS

Operative mortality and morbidity rates, including spinal cord ischemia incidence, did not differ between the groups. Operative mortality and morbidity rates, including spinal cord ischemia incidence, did not differ between the groups. In the endovascular repair group, 3 patients died due to rupture of residual false lumen in the early, and late postoperative follow-up. The 5-year rate of freedom from all-cause death, aorta-related death, and aorta-related event were 84% ± 6%, 94% ± 3% and 84% ± 6%. The endovascular repair was independently associated with all-cause death (hazard ratio [HR], 5.7; confidence interval [CI], 1.02-31.6; P = 0.04) and aorta-related event (HR, 30.9; CI 4.9-195.0; P < 0.001). In the open group, postoperative residual aortic diameter was an independent predictor of aorta-related events, and the threshold was 41 mm.

CONCLUSIONS

Open repair remains a better option than simple endovascular repair alone in DeBakey IIIb dissection, but the distal un-resected aortic portion over 41 mm was associated with late aortic events.

Influence of thoracic endovascular aortic repair on true lumen helical morphology for Stanford type B dissections

OBJECTIVE

Thoracic endovascular aortic repair (TEVAR) can change the morphology of the flow lumen in aortic dissections, which may affect aortic hemodynamics and function. This study characterizes how the helical morphology of the true lumen in type B aortic dissections is altered by TEVAR.

METHODS

Patients with type B aortic dissection who underwent computed tomography angiography before and after TEVAR were retrospectively reviewed. Images were used to construct three-dimensional stereolithographic surface models of the true lumen and whole aorta using custom software. Stereolithographic models were segmented and co-registered to determine helical morphology of the true lumen with respect to the whole aorta. The true lumen region covered by the endograft was defined based on fiducial markers before and after TEVAR. The helical angle, average helical twist, peak helical twist, and cross-sectional eccentricity, area, and circumference were quantified in this region for pre- and post-TEVAR geometries.

RESULTS

Sixteen patients (61.3 ± 8.0 years; 12.5% female) were treated successfully for type B dissection (5 acute and 11 chronic) with TEVAR and scans before and after TEVAR were retrospectively obtained (follow-up interval 52 ± 91 days). From before to after TEVAR, the true lumen helical angle (-70.0 ± 71.1 to -64.9 ± 75.4°; P = .782), average helical twist (-4.1 ± 4.0 to -3.7 ± 3.8°/cm; P = .674), and peak helical twist (-13.2 ± 15.2 to -15.4 ± 14.2°/cm; P = .629) did not change. However, the true lumen helical radius (1.4 ± 0.5 to 1.0 ± 0.6 cm; P < .05) and eccentricity (0.9 ± 0.1 to 0.7 ± 0.1; P < .05) decreased, and the cross-sectional area (3.0 ± 1.1 to 5.0 ± 2.0 cm²; P < .05) and circumference (7.1 ± 1.0 to 8.0 ± 1.4 cm; P < .05) increased significantly from before to after TEVAR. The distinct bimodal distribution of chiral and achiral native dissections disappeared after TEVAR, and subgroup analyses showed that the true lumen circumference of acute dissections increased with TEVAR, although it did not for chronic dissections.

CONCLUSIONS

The unchanged helical angle and average and peak helical twists as a result of TEVAR suggest that the angular positions of the true lumen are constrained and that the endografts were helically conformable in the angular direction. The decrease of helical radius indicated a straightening of the corkscrew shape of the true lumen, and in combination with more circular and expanded lumen cross-sections, TEVAR produced luminal morphology that theoretically allows for lower flow resistance through the endografted portion. The impact of TEVAR on dissection flow lumen morphology and the interaction between endografts and aortic tissue can provide insight for improving device design, implantation technique, and long-term clinical outcomes.

Applicability of the Zenith Inner Branched Arch Endograft

Purpose: To evaluate the clinical and anatomical features of patients with arch pathology to better understand the applicability of the Zenith inner branched arch endograft (IBAE). Materials and Methods: A retrospective review was performed of 60 consecutive patients (mean age 62.5 years; 42 men) who presented with nonruptured aortic arch pathology at a single institution between 2009 and 2016. Patients were stratified into standard (no previous cardiac surgery, <80 years old, and no significant medical comorbidity), high (previous cardiac surgery or significant comorbidity), or prohibitive risk (turned down for operative intervention) for operative intervention. Anatomical measurements of the aorta were obtained on computed tomography scans; anatomical suitability was based on the device's instructions for use. Results: Overall, 27 (45%) patients had anatomy amenable to treatment with the existing IBAE. Inadequate proximal seal length and large ascending aortic diameters were the primary reasons for anatomical unsuitability. Shortening the inner curve seal zone from 25 to 15 mm and increasing the proximal seal zone diameter from 38 to 42 mm increased anatomical suitability to include 49 (82%) patients. Of these, 31 were in the high-risk cohort and 7 were deemed prohibitive risk; therefore, IBAE would have been strongly considered in these 38 patients. Conclusion: Based on anatomical criteria alone, nearly half of patients with aortic arch pathology have anatomy suitable to the Zenith IBAE in its current design. Arch branch vessel anatomy was not a limitation of the device. From a clinical standpoint, if endovascular repair were reserved for those at high or prohibitive risk for open repair, approximately 30% of patients would likely benefit from the IBAE in its current form.

Hybrid versus in vitro fenestration for preserving the left subclavian artery in patients undergoing thoracic endovascular aortic repair with unfavorable proximal landing zone

Purpose

To compare hybrid and in vitro fenestration procedures for preserving the left subclavian artery in thoracic endovascular aortic repair (TEVAR) with unfavorable proximal landing zone.

Methods

Retrospective comparison of data from 49 consecutive patients who underwent left subclavian artery revascularization during TEVAR by either hybrid or fenestration approaches from January 2015 to March 2018. Procedural duration, and 30-day rates of procedural success, mortality and complications (endoleaks, cerebral infarction, spinal cord ischemia, left arm ischemic symptoms, and delirium) were compared.

Results

For hybrid procedure ( n = 32) vs. fenestration ( n = 17) groups, which were age and gender matched: procedural success rate was 100%, with significantly longer procedural duration (248.4 ± 40.9 vs. 60.6 ± 16.8 min; t = –22.653, P = 0.000) and similar 30-day complication rate (18.8% vs. 11.8%; χ2 = 0.397, P = 0.529). At 12.7 ± 9.3 months’ follow-up, there were no cases of death, spinal cord ischemia, or other complications in either group.

Conclusions

In this retrospective, single-center comparison, both hybrid and in vitro fenestration approaches for reconstructing the left subclavian artery in TEVAR with unfavorable proximal landing zone appeared safe and effective, with shorter procedural duration for fenestration. Larger studies with longer term follow-up are warranted.

High intimal flap mobility assessed by intravascular ultrasound is associated with better short-term results after TEVAR in chronic aortic dissection

Thoracic endovascular aortic repair (TEVAR) in chronic aortic dissection remains controversial. We analysed whether a high intimal flap mobility (IFM) of the dissection membrane has an impact on aortic remodelling after TEVAR in chronic Type B aortic dissection. Patients undergoing TEVAR with intravascular ultrasound (IVUS) were analysed and IFM was calculated. High IFM was defined as maximum flap amplitude >3 mm. For determining aortic remodelling, the degree of true lumen (TL) expansion was analysed in the last available follow-up CT. Fifty-two patients (63.6 ± 15.4 years) with a mean follow-up of 26.6 ± 20.7 months were analysed. The mobile flap group (n = 29) showed higher absolute TL expansion at the distal stent-graft (5.9 ± 3.1 vs. 3.3 ± 5.4 mm; p = 0.036) and a higher increase in TL diameter (18 ± 10 vs. 9 ± 15%; p = 0.017) compared to the non-mobile group (n = 23). Basic TEVAR-related outcome characteristics were comparable, but the mobile intimal flap group showed a lower re-intervention rate (3 vs. 8pts.; p = 0.032) in chronic dissections. High IFM in chronic Type B aortic dissection is linked to improved aortic remodelling and is associated with a lower re-intervention rate over time. IVUS assessment of IFM in chronic Type B aortic dissection might be helpful in identifying patients with better remodelling after TEVAR.

Distal landing zone optimization before endovascular repair of aortic dissection

BACKGROUND

The general goals of endovascular management in chronic distal thoracic aortic dissection are optimizing the true lumen, maintaining branch patency, and promoting false lumen (FL) thrombosis. Distal seal can be challenging in chronic distal thoracic aortic dissection due to the well-established secondary fenestrations and fibrotic septum. We describe our approach of distal landing zone optimization (DLZO) to enable full-diameter contact of the distal endoprosthesis.

MATERIALS AND METHODS

Our experience includes 19 procedures in 16 patients (12 male, age 68 ± 8 years) between May 2014 and November 2017. A history of previous ascending repair for type A dissection was present in 8 patients. Treatment indication was enlarging aneurysm in all subjects, and 4 patients had associated chronic visceral or distal ischemia. Point septal fenestrations were expanded by serial balloon dilation and/or wire-pull approaches. Balloon molding was used to ensure complete endograft apposition and FL collapse.

RESULTS

One death occurred due to aortic perforation during wire-pull fenestration in a patient with heavily calcified and angulated aorta. The remaining procedures were accomplished safely and successfully. Balloon fenestration was used in 16 procedures, alone or in combination with a limited wire pull component. Adjunct procedures for distal seal included surgeon-modified fenestrated stent graft (3), iliac branch device (3), parallel superior mesenteric artery stent-graft (1), renal artery or superior mesenteric artery stent-graft (4), iliac stent (3), and plug obliteration of FL (5). Reintervention was required in 3 patients due to delayed loss of seal after the initial procedure (3, 8, and 12 months). Two were managed by repeat DLZO and distal extension. The third had distal extension via a surgeon-modified fenestrated stent-graft component. Follow-up imaging was available in 14 patients (16.0 ± 12.5 months, range: 1-33), with stable or regressed sac diameter with complete or near-complete thrombosis of the FL in all patients.

CONCLUSIONS

DLZO enabled creation of a distal seal zone in all patients. Residual retrograde filling of the FL is a marker of procedure failure, especially when seal segment length or feasible endoprosthesis oversizing are marginal. Insufficient landing segment can be circumvented with the use of a fenestrated or branched device to accomplish seal in the visceral aorta or iliac bifurcation. Adjunct FL ablation is also a valuable technique to promote FL thrombosis.

Indications for Thoracic EndoVascular Aortic Repair (TEVAR): A Brief Review

The utility of Thoracic EndoVascular Aortic Repair (TEVAR) continues to progress at a very rapid rate. Initially implemented for the treatment of thoracic aortic aneurysms, TEVAR has evolved to treat a variety of aortic pathologies and reduce overall morbidity and mortality rates compared with traditional open surgical repair. Given the rapidly evolving nature of endovascular thoracic intervention, we hereby briefly review the current literature on the evolving applications of TEVAR. TEVAR continues to rapidly evolve and is being applied to a growing number of aortic pathologies. Given the perioperative, short- and mid-term morbidity and mortality rates, TEVAR is quickly surpassing traditional open surgical intervention as the ideal procedure for patients undergoing intervention of the descending thoracic aorta and applicability to ascending and arch pathologies is being explored. However, as more data becomes available TEVAR may be associated with higher rates of reoperative requirements. Data remains limited on the long-term efficacy of the intervention and should continue to be investigated.

Custom-Made Endograft for Endovascular Repair of Thoraco-Abdominal Aneurysm and Type B Dissection: Single-Centre Experience

AIMS

To report a series of patients treated with the Jotec custom-made endograft for thoraco-abdominal aneurysms and dissections and identify predictive factors for re-intervention.

METHODS

We retrospectively analysed 49 patients unsuitable for surgery, treated between 2011 and 2017 (71.3 ± 9.5 years; 15 females). Indications included Crawford type 4 aneurysm in 25 patients, type 3 in 13, type 2 in 4, type 1 in 2 and chronic aneurysmal dilatation of the false lumen following dissection in 5 cases. Mean aneurysm diameter was 58.7 ± 8.4 mm. The study aims were to assess procedural success, complications rate, mortality and long-term follow-up. We also analysed factors that predicted the need for re-intervention.

RESULTS

The endograft was successfully deployed in all patients, catheterization of the fenestration and/or branches was achieved in 152/156 (97.4%) vessels. Early complications occurred in 10 patients (3 paraplegia, 3 haemorrhages, pancreatitis, aortic rupture, iliac artery rupture, 2 strokes). Thirty-day mortality was 10.2% and 180-day mortality 14.3%; two non procedure related deaths occurred. Mean follow-up was 23.6 ± 29.9 months [range 1-80]. No patients needed surgical explantation or developed significant renal impairment. Endoleak rate was 34.6% and re-intervention rate 9.7%. The aneurysm sac reduced or was stable in 36/49, and enlarged in 9/49 patients prompting re-intervention. Primary, primary-assisted and secondary patency of fenestrations/branches at 80 months was 90, 96 and 100%. Re-intervention was required more frequently in braches than in fenestrations, most commonly the external type branches.

CONCLUSIONS

The results of the Jotec endograft are comparable to other devices, with acceptable complication and re-intervention rates. Fenestration and inner-branch should be preferred due to lower re-intervention rates.