Endovascular Repair of Thoracic Aortic Disease: Early and Midterm Experience

Prediction of endovascular leaks after thoracic endovascular aneurysm repair though machine learning applied to pre-procedural computed tomography angiographs

To predict endoleaks after thoracic endovascular aneurysm repair (TEVAR) we submitted patient characteristics and vessel features observed on pre- operative computed tomography angiography (CTA) to machine-learning. We evaluated 1-year follow-up CT scans (arterial and delayed phases) in patients who underwent TEVAR for the presence or absence of an endoleak. We evaluated the effect of machine learning of the patient age, sex, weight, and height, plus 22 vascular features on the ability to predict post-TEVAR endoleaks. The extreme Gradient Boosting (XGBoost) for ML system was trained on 14 patients with- and 131 without endoleaks. We calculated their importance by applying XGBoost to machine learning and compared our findings between with those of conventional vessel measurement-based methods such as the 22 vascular features by using the Pearson correlation coefficients. Pearson correlation coefficient and 95% confidence interval (CI) were r = 0.86 and 0.75 to 0.92 for the machine learning, r = - 0.44 and - 0.56 to - 0.29 for the vascular angle, and r = - 0.19 and - 0.34 to - 0.02 for the diameter between the subclavian artery and the aneurysm (Fig. 3a-c, all: p < 0.05). With machine-learning, the univariate analysis was significant higher compared with the vascular angle and in the diameter between the subclavian artery and the aneurysm such as the conventional methods (p < 0.05). To predict the risk for post-TEVAR endoleaks, machine learning was superior to the conventional vessel measurement method when factors such as patient characteristics, and vascular features (vessel length, diameter, and angle) were evaluated on pre-TEVAR thoracic CTA images.

Severe Tortuosity of the Distal Descending Thoracic Aorta Affects the Accuracy of Distal Deployment During a Thoracic Endovascular Aortic Repair

PURPOSE

An accurate distal deployment is essential for successful thoracic endovascular aortic repair (TEVAR) of a paradiaphragmatic aortic aneurysm. This study aimed to investigate the anatomical and intraoperative factors that affect the accuracy of distal deployment during TEVAR.

METHODS

We conducted a retrospective review of preoperative and postoperative computed tomography scans of 426 patients undergoing TEVAR at our institution between October 2008 and May 2021, of which the stent-graft was attempted to be deployed just above the celiac axis or the superior mesenteric artery in 56 patients. Based on the anatomical factors related to the malposition (deployed >10 mm away from the target vessel) and the greater curve to the straight-line ratio (G/S ratio), the patients were categorized as severe tortuosity (n=21) and mild tortuosity (n=35) groups to compare the operative and clinical outcomes.

RESULT

Stent-graft malpositioning occurred in 21 cases. Among all anatomical variables, only the G/S ratio was significantly larger in the malpositioned cases (p=0.049). A cutoff G/S ratio value of 1.15 was determined using the receiver operating curve analysis. In the severe tortuosity group, the distal end of the stent-graft was significantly farther (median: 10.0 [interquartile range (IQR): 2.5-19.5] mm vs 3.0 [0-8.0] mm; p=0.015) from the target vessel, and the tilt angle of the stent-graft's distal edge was larger (median: 21.4 [IQR: 15.8-24.5] vs 9.5 [5.5-12.5] degree; p<0.01) than that in the mild tortuosity group. Both groups were comparable for the incidence of a primary type Ib endoleak (p=0.454), a secondary type Ib endoleak (p=1.0), and the rate of distal reintervention (p=0.276).

CONCLUSION

Severe tortuosity in the distal descending thoracic aorta is associated with a malpositioned and tilted distal end of the stent-graft.

CLINICAL IMPACT

Thoracic endovascular aortic repair (TEVAR) for paradiaphragmatic thoracic aortic aneurysms requires accurate distal landing. In this paper, a retrospective CT analysis revealed that the greater curve to the straight-line ratio (G/S ratio) was associated to affects the malposition of the stent graft, defined as being deployed more than 10 mm away from the target vessel. Further, a comparative analysis based on the G/S ratio demonstrated that severe aortic tortuosity was associated with a more distal and tilted deployment of the stent graft.

Endovascular Repair for Thoracic Aortic False Aneurysms: Single-Center Experience in 102 Patients

BACKGROUND

Thoracic aortic false aneurysm is unusual and experience with endovascular repair is limited. We evaluate the efficacy of endovascular repair in patients with thoracic aortic false aneurysms.

METHODS

The early and midterm outcomes of endovascular repair in 102 patients with thoracic aortic false aneurysms were analyzed.

RESULTS

There were 80 men and 22 women (age 54.9 ± 13.7 years). Emergent or urgent endovascular repair was done in 19 cases (18.6%) and elective in 83 (81.4%). Procedure was successful in 99.0%. Early death occurred in 4 patients (3.9%). No early death occurred in elective patients. Early complications occurred in 7 patients (6.9%). Follow-up was complete in 100% for 24.0 ± 18.5 months (range, 1.5 to 67.3). Fourteen late deaths occurred (13.7%). Late events occurred in 9 patients (8.8%). Survival at 6 month, 1 year and 3 years was 90.7%, 86.7% and 84.5%, respectively.

CONCLUSIONS

Satisfactory early and midterm outcomes have been achieved with endovascular repair in this series. Although emergent or urgent patients had higher rates of early mortality and morbidity, the majority of them achieved stable late survival as long as they survived at least 6 months. These results argue favorably for use of endovascular repair in the management of patients with thoracic aortic false aneurysms.

Assessment of a new type I endoleak repair technique using an anchoring device

OBJECTIVE

Type I endoleaks are one of the most frequent and life-threatening complications of thoracic endovascular aortic repair. This study aimed to assess the use of suture-anchoring devices for repairing type I endoleaks.

METHODS

The descending aortic aneurysm model (saccular type) was made by side-to-end anastomosis to a Dacron graft. A Matsui-Kitamura stent graft was deployed to create a proximal type I endoleak. Approximately 5 mm above the upper rim of the anastomosis, the aorta was punctured by the pistol of the suture-anchoring device with a T-shaped bar under fluoroscopy. Sutures were applied until angiography showed the absence of a type I endoleak. During the process, two pressure measurements were used to perform continuous assessments of aortic pressure and intra-aneurysm sac pressure.

RESULTS

A mean ± SD of 5 ± 1 anchoring shots were used to eliminate type I endoleaks. The device performed well, and no complications were observed. The mean ± SD intrasac pressures before stent graft deployment, during endoleak maintenance, and after repair were 118 ± 5, 61 ± 4, and 26 ± 5 mm Hg, respectively. The postrepair pressure was significantly decreased (P < 0.001; Student t test).

CONCLUSIONS

Despite some anatomic and clinical limitations identified during the experiments, the effectiveness of the suture-anchoring device was confirmed. Further improvement of the device will soon lead to its use as a less invasive endoleak repair procedure.

Percutaneous occlusion of the left subclavian and celiac arteries before or during endograft repair of thoracic and thoracoabdominal aortic aneurysms with detachable nitinol vascular plugs

PURPOSE

To review an experience with the Amplatzer vascular plug (AVP) for prevention of type II endoleaks during endovascular aneurysm repair (EVAR) of thoracic and thoracoabdominal aneurysms.

MATERIALS AND METHODS

Retrospective review was undertaken of 14 patients undergoing transcatheter occlusion of the left subclavian (n = 12) or celiac artery (n = 2) with the AVP as part of EVAR of thoracic and thoracoabdominal aneurysms at a single institution. Procedural criteria evaluated were success at target vessel occlusion, the number of AVPs used, use of adjunctive embolization devices, and embolization-related ischemic end-organ events. Follow-up imaging criteria included evaluation of persistent target vessel occlusion, evidence of device migration, and the presence and characterization of endoleak secondary to AVP failure.

RESULTS

Complete target vessel occlusion was documented for all cases. In six cases, more than one AVP was placed, with an average of 1.5 devices per patient. In two cases, adjunctive coils were placed. Computed tomographic or magnetic resonance angiography follow-up was available for all patients (mean follow-up, 419 days; range 28-930 d). No case showed evidence of device migration or type II endoleak resulting from AVP failure. There was a single instance of left subclavian artery recanalization without type II endoleak. There were no embolization-related ischemic end-organ events.

CONCLUSIONS

Transcatheter arterial occlusion of the subclavian and celiac arteries with the AVP is a valuable adjunct to endografting in cases in which side branch embolization is necessary to extend the landing zone.

The burden of hard atherosclerotic plaques does not promote endoleak development after endovascular aortic aneurysm repair: a risk stratification

PURPOSE

To objectify the influence of the atherosclerotic burden in the proximal landing zone on the development of endoleaks after endovascular abdominal aortic aneurysm repair (EVAR) or thoracic endovascular aneurysm repair (TEVAR) using objective aortic calcium scoring (ACS).

MATERIALS AND METHODS

This retrospective observation study included 267 patients who received an aortic endograft between 1997 and 2010 and for whom preoperative computed tomography (CT) was available to perform ACS using the CT-based V600 method. The mean follow-up period was 2 ± 2.3 years.

RESULTS

Type I endoleaks persisted in 45 patients (16.9%), type II in 34 (12.7%), type III in 8 (3%), and type IV or V in 3 patients, respectively (1.1% each). ACS in patients with type I endoleaks was not increased: 0.029 ± 0.061 ml compared with 0.075 ± 0.1349 ml in the rest of the patients, (p > 0.05; Whitney-Mann U-Test). There were significantly better results for the indication "traumatic aortic rupture" than for the other indications (p < 0.05). In multivariate logistic regression analyses, age was an independent risk factor for the development of type I endoleaks in the thoracic aorta (Wald 9.5; p = 0.002), whereas ACS score was an independent protective factor (Wald 6.9; p = 0.009). In the abdominal aorta, neither age nor ACS influenced the development of endoleaks.

CONCLUSION

Contrary to previous assumptions, TEVAR and EVAR can be carried out without increasing the risk of an endoleak of any type, even if there is a high atherosclerotic "hard-plaque" burden of the aorta. The results are significantly better for traumatic aortic.

Incomplete endograft apposition to the aortic arch: bird-beak configuration increases risk of endoleak formation after thoracic endovascular aortic repair

PURPOSE

To determine the clinical importance of the bird-beak configuration after thoracic endovascular aortic repair (TEVAR).

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the requirement to obtain informed consent from patients. Sixty-four patients (40 men, 24 women; mean age, 64 years) who underwent TEVAR were evaluated. The treated diseases included dissection (n = 29), degenerative aneurysm (n = 13), acute traumatic transection (n = 8), pseudoaneurysm (n = 4), penetrating aortic ulcer (n = 6), intramural hematoma (n = 2), and mycotic aneurysm (n = 2). Bird-beak configuration, defined as the incomplete apposition of the proximal endograft with a wedge-shaped gap between the device and the aortic wall, was assessed with postprocedural CT angiography. The presence and length of the bird-beak configuration were compared with the formation of endoleaks and adverse clinical events.

RESULTS

Endoleaks were detected in 26 (40%) of the 64 patients, including 14 with type Ia endoleak formation, one with type Ib endoleak formation, six with type II endoleak formation (from the left subclavian artery), two with type IIo endoleak formation (from other arteries), and three with type III endoleak formation. Bird-beak configuration was observed in 28 (44%) of 64 patients and correlated significantly with the risk of developing a type Ia or IIa endoleak (P < .01). Mean bird-beak length was significantly longer (P < .01) in patients with a type Ia or II endoleak (mean length, 14.3 and 13.9 mm, respectively) than in patients without endoleaks (mean length, 8.4 mm). Adverse events included early aortic-related death in three patients, additional treatment for endoleak in eight patients, and stent-graft collapse or infolding in six patients.

CONCLUSION

Detection of bird-beak configuration is helpful in the prediction of adverse clinical events after TEVAR.

Learning curve analysis of thoracic endovascular aortic repair in relation to credentialing guidelines

OBJECTIVE

Recently, practice guideline documents have recommended the completion of different levels of interventional experience and 5 or 10 thoracic endovascular aortic cases prior to surgeon credentialing. This study's purpose was to determine whether these requirements are valid by reviewing three surgeons' learning curves with thoracic aortic endovascular repairs.

METHODS

Between 1998 and 2006, 67 patients underwent emergent or elective endovascular repair of thoracic aortic pathologies by one of three vascular surgeons with extensive experience with catheter manipulation and abdominal aortic endografts. Following standard retrospective review, each surgeon's learning curve was analyzed using the cumulative sum failure method with a target success rate of 95% derived from the literature. The main outcome variable was primary technical success.

RESULTS

These 67 patients presented with several pathologies including elective (n = 31) and ruptured (n = 11) thoracic aortic aneurysms, acute dissections or aortic ulcers (n = 10), and acute blunt thoracic aortic trauma (n = 15). The mean age was 65 (range: 20 to 90) and the early (30 day) mortality rate was 19.4% in urgent cases (n = 36) and 0% in elective cases (n = 31). Paraplegia occurred in two patients (3%). Primary technical success was achieved in 62 cases (92.5%) and did not differ between surgeons (92.6%, 91.3%, 94.1%, respectively; P = .9). Each surgeon's cases were plotted sequentially and the resulting learning curves were similar. Although acceptable outcomes were obtained throughout the study period, improved results, compared with the target success rate, were not achieved until each surgeon treated 5 to 10 patients.

CONCLUSION

This study supports the case volume requirements of the Society for Vascular Surgery credentialing guidelines, which also requires extensive catheter and guidewire experience. With this background in catheter manipulation and endovascular abdominal aortic repair, surgeons can achieve optimal outcomes with thoracic aortic lesions following 5 to 10 cases.