The fate of the abdominal aorta after endovascular treatment in chronic Debakey IIIb aneurysm

Exploring hemodynamic mechanisms and re-intervention strategies for partial false lumen thrombosis in Stanford type B aortic dissection after thoracic aortic endovascular repair

OBJECTIVES

False lumen (FL) thrombosis status for Stanford type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR) is critical for evaluating aortic remodeling and long-term prognosis. This study aimed to monitor the morphology evolution of partial FL thrombosis (PFLT) and its hemodynamic conditions through an innovative approach, providing a re-intervention strategy from both morphologic and hemodynamic perspectives.

METHODS

Three-dimensional geometries are extracted from a five-year follow-up of CTA images for TBAD after TEVAR. The morphology and hemodynamics of PFLT are comprehensively analyzed based on patient-specific reconstructions and computational fluid dynamics (CFD). The impact of various strategies treating risk factors of PFLT, including proximal entry closure, left renal artery stenting, or accessory renal artery embolism on hemodynamics is assessed.

RESULTS

The introduced morphologic approaches appropriately reflected the evolution of PFLT. Gradual dilation of FL (surface area from 82.63cm2 to 98.84cm2, volume from 45.12 mL to 63.40 mL, increase in distal tear (from 3.72 cm to 4.32 cm), and fluctuation of thrombosis-blood lumen boundary are observed. For further surgical preparation in the absence of unanimously recognized re-intervention indicators, velocity and wall shear stress distributions reveal different simulated re-interventions have distinctly suppressive effects on hemodynamic conditions within the PFLT, providing valuable insights for further surgical preparation.

CONCLUSIONS

The present study demonstrates a re-intervention strategy for PFLT in TBAD patients after TEVAR utilizing morphologic and hemodynamic analyses. Acknowledging the deterioration of PFLT may result in adverse long-term outcomes, this strategy might offer an alternative approach for clinical monitoring and management of related patients.

Fate and Consequences of the False Lumen after TEVAR in Type B Aortic Dissection

BACKGROUND

Type B aortic dissection (TBAD) occurs due to an entry tear in the intimal layer of the aorta distal to the origin of the left subclavian artery where blood enters the newly formed false lumen (FL) and extends distally or proximally to form a dissection over an indeterminate length of the aorta which, over time, may eventually rupture. Thoracic endovascular aortic repair (TEVAR) aims to seal off the entry tear proximally with the stent-graft, occluding the origin of the dissection and excluding the FL. Nevertheless, in some cases, the perfusion to the FL is maintained, hindering the aortic remodelling process and increasing the risk of aneurysmal degeneration and rupture, particularly in the abdominal aorta where evidence suggest that remodelling is slower. This review examines the long-term effects of a patent or partially thrombosed FL on clinical outcomes following TEVAR in TBAD, also highlighting the pathological processes behind negative aortic remodelling. Another aim of this review is to provide an overview and appraisal of the currently available techniques for managing a patent or partially thrombosed FL to prevent long-term morbidity occurring.

METHODS

A comprehensive literature search was performed using several search engines including PubMed, Ovid, Google Scholar, Scopus, and Embase to identify and extract relevant studies.

RESULTS

Evidence in the literature show that a partially thrombosed FL is more dangerous than a patent FL due to the occlusion of the distal re-entry tears, impeding outflow and increasing mean arterial and diastolic pressures, whereas the latter is decompressed via distal re-entry sites. FL thrombosis and satisfactory remodelling is sometimes achieved in as few as 40% of patients after TEVAR due to the maintained perfusion of the FL either at the level of the thoracic or abdominal aorta. However, although the thoracic aorta is predominantly covered by the TEVAR stent-graft, poorer remodelling and more dilation is seen in the abdominal aorta. Several techniques are available to embolize the FL, including the Provisional Extension to Induce Complete Attachment, Stent Assisted Balloon Induced Intimal Disruption and Relamination in Aortic Dissection Repair, candy-plug, and Knickerbocker techniques.

CONCLUSIONS

The management of TBAD is invariably TEVAR to seal off the proximal entry tear while extending the repair distally to completely exclude the FL. A risk of aortic wall dilatation distal to TEVAR stent-graft remains; hence, regular monitoring and accurate imaging are essential. At present, a patent FL can be treated using a range of different endovascular techniques.

The Number of Preoperative Abdominal False Lumen-perfused Small Branches Is Related to Abdominal Aortic Remodeling after Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

BACKGROUND

Abdominal aortic enlargement (AAE) is a commonly seen complication after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD). This study assessed the relationship between preoperative abdominal false lumen-perfused small branches (pre-AFLSBs) and risk of AAE after TEVAR for TBAD extending through the abdominal aorta.

METHODS

One hundred and eighty-four patients with TBAD who had been treated by TEVAR at 4 hospitals in China were stratified in accordance with median pre-AFLSBs: ≤8 (group A) and >8 (group B). AAE was defined as ≥20% increase in abdominal total aortic volume, measured using imaging software featuring centerline analysis, on most recent postoperative computed tomography angiography relative to preoperative examination. Multivariable Cox proportional hazard regression was used to evaluate the relationship between the number of pre-AFLSBs and the risk of AAE after TEVAR.

RESULTS

At median 12.4 months imaging follow-up, AAE was present in 65 patients at higher cumulative rate (log-rank test P < 0.001) in group B, which had more frequent partially thrombosed or patent abdominal false lumen than group A at 6-12 months (P < 0.01) and 12-24 months (P = 0.03) of follow-up. In a multivariable Cox proportional hazard regression model, the number of pre-AFLSBs was independently associated with risk of AAE after TEVAR (hazard ratio [for one increase], 1.10; 95% confidence interval, 1.00-1.21; P = 0.04) after adjustment for age, gender, dissection chronicity, Society for Vascular Surgery risk score, preoperative maximum descending aortic diameter, false lumen status of the abdominal aorta, numbers of false lumen-perfused visceral arteries, abdominal intimal larger tears, and preoperative abdominal intimal small tears, and dissection length and descending aortic length ratio.

CONCLUSIONS

The number of pre-AFLSBs was positively associated with the risk of AAE after TEVAR for TBAD extending through the abdominal aorta.

Late Aortic Expansion After Thoracic Endovascular Aortic Repair for Chronic DeBakey IIIb Dissection

BACKGROUND

The efficacy of thoracic endovascular aortic repair (TEVAR) for chronic DeBakey IIIb aortic dissection is still under discussion. This study was performed to investigate the incidence of and risk factors for late aortic expansion after TEVAR for chronic DeBakey IIIb aortic dissection.

METHODS

From March 2014 to April 2019, a total of 35 patients with chronic DeBakey IIIb aortic dissection underwent TEVAR in our institution. Risk factors for aortic expansion events were examined by stepwise Cox regression analysis. Aortic expansion events were defined as reintervention for expansion or aortic expansion of greater than 5 mm.

RESULTS

No operative death occurred, and the 2-year survival rate was 96.8%. The 1- and 2-year rates of freedom from reintervention were 87.8% and 80.2%, respectively. During follow-up, 11 patients had late aortic expansion events (4 with expansion of the thoracic aorta and 7 with expansion of the abdominal aorta). The 1- and 2-year rates of freedom from aortic expansion were 87.8% and 68.7%, respectively. Significant risk factors for expansion events were aortic dilation at the celiac level (hazard ratio [HR], 1.11; P = .015), saccular aneurysm formation of the false lumen (HR, 5.08; P = .049), and high number of residual large reentries (>5 mm) (HR, 2.78; P = .027).

CONCLUSIONS

In patients undergoing TEVAR for chronic DeBakey IIIb aortic dissection, late aortic expansion in both the thoracic and abdominal aorta remains an important issue. Aggressive additional intervention should be considered for high-risk patients with residual large reentries and aortic dilation at the celiac level.

Temporal pattern of aortic remodelling after endovascular treatment for chronic DeBakey IIIb dissection

OBJECTIVES

Endovascular treatment has emerged as a safe procedure for treating chronic DeBakey IIIb dissection. The objective of this study was to investigate the mid-term outcome and temporal pattern of aortic remodelling after endovascular treatment for DeBakey IIIb dissection.

METHODS

From 2012 to 2017, 85 patients who underwent endovascular aortic repair for DeBakey IIIb dissection were enrolled. The temporal pattern of aortic remodelling in terms of false lumen (FL) thrombosis [level 1 (∼T7), level 2 (T7 ∼ coeliac axis) and level 3 (coeliac trunk ∼ aortic bifurcation)] and aortic diameter [mid-thoracic level (T7), coeliac axis and the largest infrarenal abdominal aorta] was investigated on serial follow-up computed tomography scan.

RESULTS

Eighty-five patients underwent endovascular treatment during the study period. Male sex was a significant risk factor for repetitive reintervention and segments 2 and 3 FL thrombosis. The preoperative FL diameter at T7 was significantly associated with FL diameter regression. The number of visceral vessels from the FL and residual DeBakey IIIb dissection after type A repair were significant factors for FL growth at the coeliac trunk and at the largest infrarenal abdominal aorta. The overall mortality was 3 (3.6%).

CONCLUSIONS

Endovascular treatment is a safe strategy in the management of DeBakey IIIb dissection. However, unfavourable aortic remodelling and repetitive reintervention were expected in male patients with a large number of visceral vessels from the FL and residual DeBakey IIIb dissection after type A repair. Endovascular treatment should be cautiously considered, and close follow-up is required for these patients.