Aneurysm expansion after stent-graft placement in the absence of endoleak

Feasibility of shear wave sonoelastography to detect endoleak and evaluate thrombus organization after endovascular repair of abdominal aortic aneurysm

PURPOSE

To investigate the feasibility of shear wave sonoelastography (SWS) for endoleak detection and thrombus characterization of abdominal aortic aneurysm (AAA) after endovascular repair (EVAR).

MATERIALS AND METHODS

Participants who underwent EVAR were prospectively recruited between November 2014 and March 2016 and followed until March 2019. Elasticity maps of AAA were computed using SWS and compared to computed tomography angiography (CTA) and color Doppler ultrasound (CDUS). Two readers, blinded to the CTA and CDUS results, reviewed elasticity maps and B-mode images to detect endoleaks. Three or more CTAs per participant were analyzed: pre-EVAR, baseline post-EVAR, and follow-ups. The primary endpoint was endoleak detection. Secondary endpoints included correlation between total thrombus elasticity, proportion of fresh thrombus, and aneurysm growth between baseline and reference CTAs. A 3-year follow-up was made to detect missed endoleaks, EVAR complication, and mortality. Data analyses included Cohen's kappa; sensitivity, specificity, and positive predictive value (PPV); Pearson coefficient; and Student's t tests.

RESULTS

Seven endoleaks in 28 participants were detected by the two SWS readers (k = 0.858). Sensitivity of endoleak detection with SWS was 100%; specificity and PPV averaged 67% and 50%, respectively. CDUS sensitivity was estimated at 43%. Aneurysm growth was significantly greater in the endoleak group compared to sealed AAAs. No correlation between growth and thrombus elasticity or proportion of fresh thrombus in AAAs was found. No new endoleaks were observed in participants with SWS negative studies.

CONCLUSION

SWS has the potential to detect endoleaks in AAA after EVAR with comparable sensitivity to CTA and superior sensitivity to CDUS.

KEY POINTS

• Dynamic elastography with shear wave sonoelastography (SWS) detected 100% of endoleaks in abdominal aortic aneurysm (AAA) follow-up that were identified by a combination of CT angiography (CTA) and color Doppler ultrasound (CDUS). • Based on elasticity maps, SWS differentiated endoleaks from thrombi within the aneurysm sac (p < 0.001). • After 3-year follow-up, no new endoleaks were observed in SWS negative examinations.

Gender Differences in Aortic Neck Morphology in Patients with Abdominal Aortic Aneurysms Undergoing Elective Endovascular Aneurysm Repair

BACKGROUND

Previous studies have demonstrated that women tend to have adverse aortic neck morphology leading to exclusion of some women from undergoing endovascular aneurysm repair (EVAR). The objective of this study is to investigate differences in aortic neck morphology in men versus women, changes in the neck morphology and sac behavior after EVAR, and investigate how these features may influence outcomes.

METHODS

We conducted a retrospective review of elective EVARs (2004-2013). We excluded patients who underwent elective EVAR with no postoperative imaging available and those patients with fenestrated repairs. Using TeraRecon and volumetric analysis, several features were investigated. These included percent thrombus, shape, length, angulation of the neck, and changes in neck and abdominal aortic aneurysm diameter.

RESULTS

A total of 146 patients were found to meet inclusion criteria (115 men and 31 women) with similar baseline characteristics. Neck angulation was greater in women (23.9° vs. 13.5°; P < 0.028). The percent thrombus in women was higher than men (35.4% vs. 31%; P < 0.02). Abdominal aneurysm's were smaller in women at 1 year (4.2 cm vs. 5.1 cm; P < 0.002), and secondary interventions were higher in men (11.3% vs. 0%; P < 0.05). Other features such as neck shape, changes in neck diameter, neck length, and percent oversizing of graft where not statistically different between genders.

CONCLUSIONS

Gender differences in neck characteristics and changes in neck morphology do not appear to adversely affect EVAR outcomes. Longer follow-up is necessary to further assess whether these findings are clinically durable.

Thoracic CT Findings Following Endovascular Stent-Graft Treatment for Thoracic Aortic Aneurysm

PURPOSE

To investigate the transient computed tomographic (CT) findings and morphological characteristics of the descending thoracic aorta following endovascular repair of thoracic aortic aneurysm (TAA).

METHODS

Of 50 TAAs repaired using custom-made endoprostheses between May 1997 and September 2005, 35 (25 men; mean age 67 years) were successfully treated and followed for >3 months by thoracic CT. The TAA etiologies were 22 degenerative/atherosclerotic, 7 dissection-related from intramural hematoma, 2 traumatic, 2 anastomotic, and 2 penetrating ulcers. The CT findings following stent-graft placement were retrospectively studied.

RESULTS

Over a mean follow-up of 27.0+/-25 months (range 3-92), periaortic changes were observed in 17 (48.6%) patients, and the amount of pleural effusion increased in 13 (37.1%). In all cases, these findings disappeared without specific treatment during the follow-up period. Late secondary endoleak was observed in 1 (2.9%) patient, and there was 1 (2.9%) caudal migration of the proximal end of the stent-graft. Five (14.3%) aneurysms increased in size. Two patients, both with dissection, showed aortic neck dilatation. There was a positive relationship between neck dilatation and dissection-related TAA etiology (p = 0.035).

CONCLUSION

Although aortic neck dilatation is less common after endovascular TAA repair than after abdominal repairs, patients with dissection-related TAA may be a subgroup prone to aneurysm neck dilatation.

Reversible endotension associated with excessive warfarin anticoagulation

An aortic aneurysm was successfully treated with an endovascular stent graft, with no evidence of endoleak and documented progressive aortic diameter reduction during the first 23 months. At 29 months, the patient had documented enlargement of the aneurysm sac associated with excessive anticoagulation with warfarin. No evidence of endoleak could be demonstrated with any diagnostic modality. Progressive aneurysm sac diameter regression was documented after reversal of excessive anticoagulation to therapeutic levels (international normalized ratio of 2 to 3). Strict monitoring of coagulation profile in patients after endovascular aneurysm repair requiring anticoagulation with warfarin is recommended to avoid this complication, which to our knowledge has not been previously reported.

Development of a new method for endovascular aortic repair: combination therapy of cell transplantation and stent grafts with a drug delivery system

BACKGROUND

Endovascular aortic repair by stent grafts (S/Gs) has been developed as a less invasive treatment for aortic aneurysms. However, some aneurysmal cavities can remain without organization, causing re-expansion. We demonstrated previously that transplantation of a cell combination (myoblasts and fibroblasts) promoted thrombus organization in a rat model. We also developed basic fibroblast growth factor (bFGF) slow-delivery S/Gs coated with elastin and impregnated with bFGF. Here, we evaluated the effects of cell transplantation combined with bFGF slow release on canine thoracic aortic aneurysmal sacs after S/Gs repair.

METHODS AND RESULTS

Thoracic aortic aneurysms were surgically created with jugular vein patches in 15 beagles. Myoblasts and fibroblasts of autologous skeletal muscle were isolated and cultured for cell transplantation. The S/Gs had 6 holes and produced endoleaks in the excluded cavities. Collagen gel (gel group, n=5) or a mixture of skeletal myoblasts and fibroblasts with collagen gel (cell group, n=5) were injected into the aneurysmal sacs excluded by the S/Gs. We also studied the effects of combined therapy of bFGF slow-release S/Gs and cell transplantation (hybrid group, n=5). After 14 days, histological analyses revealed that the excluded aneurysmal cavities of the gel group were filled with fresh thrombus, whereas the excluded cavities in the cell-transplanted groups were occupied by organized tissue. The percentages of the organized areas relative to the excluded cavities, evaluated by Masson's trichrome staining, were 18.1+/-4.0%, 52.6+/-4.0%, and 77.1+/-6.9% in the gel, cell, and hybrid groups, respectively. Collagen fibers had already appeared, and increased numbers of alpha-smooth muscle actin-positive cells were observed in the hybrid group.

CONCLUSIONS

Cell transplantation accelerated thrombus organization. Moreover, slow release of bFGF enhanced the effects of cell transplantation. Cell transplantation into unorganized spaces may improve the outcomes of endovascular treatments of aortic aneurysms.

Aneurysm shrinkage after endovascular repair of aortic diseases

BACKGROUND

There are two graft materials for endovascular repair of aortic diseases, i.e., polyester and expanded polytetrafluoroethylene (ePTFE). The latest reports have suggested that there is graft-specific difference in outcomes. The purpose of this article was to evaluate the difference in terms of aneurysm shrinkage.

PATIENTS AND METHODS

Eighty-six patients who underwent endovascular repair of aortic diseases were included. Forty patients had true aortic aneurysms, 8 had aortic pseudoaneurysms, and 38 had aortic dissections. Eighteen patients with true aortic aneurysms were treated with stent grafts fabricated with polyester, while the other 68 patients, including 22 patients with true aneurysms, 8 patients with pseudoaneurysms, and 38 patients with aortic dissections, were treated with stent grafts fabricated with ePTFE. All patients were followed-up by computed tomography (CT) for more than 1 year. The mean follow-up term was 28 months. Computed tomography confirmed that there were sufficiently long necks, and the aneurysm or the entry tear was completely excluded without any endoleak in all patients. The diameter of the preoperative lesion was compared with that measured on follow-up CT at 1 year and at the end of the follow-up term. Increase or decrease in the diameter by more than 5 mm was defined as a significant diameter change.

RESULTS

Aneurysm shrinkage was observed in 40% of patients with true aneurysms, 88% of patients with pseudoaneurysms, and 55% of patients with aortic dissections at 1 year. There was no significant increase in patients with aneurysm shrinkage at the end of follow-up in any groups. In the case of true aortic aneurysms, shrinkage of aneurysms was observed more frequently with polyester-fabricated stent grafts (67%, 13/18) than with ePTFE-fabricated ones (18%, 4/22) at 1 year (P<.01). In contrast, expansion of aneurysms was observed only in patients treated with ePTFE (14%, 3/22). Shrinkage of the descending aorta was observed in 55% of patients with acute aortic dissections and 36% of patients with chronic aortic dissections. There was no case with aortic enlargement in either group. There was no significant difference between acute and chronic dissection in terms of shrinkage of the descending aorta.

CONCLUSION

Expanded polytetrafluoroethylene appears to be effective for the treatment of pseudoaneurysms and aortic dissections. However, polyester seems to be more effective than ePTFE when true aneurysms are to be treated.

Method of Cell Transplantation Promoting the Organization of Intraarterial Thrombus

Background— Endovascular aortic repairs have been developed as less invasive treatments for aortic aneurysms. Some aneurismal cavities, however, remain without organization, causing a re-expansion of the aneurysms. We studied cell transplantation into the aneurismal sac to promote the organization of thrombus for the complete healing of aneurysms.

Methods and Results— Skin fibroblasts and skeletal myoblasts were isolated from rats for cell transplantation. An intraarterial thrombus model was made by ligation of the carotid artery. Culture medium (medium group, n=11), collagen gel (gel group, n=11), fibroblasts with collagen gel (F group, n=15), myoblasts with collagen gel (M group, n=12), or mixture of fibroblasts and myoblasts with collagen gel (F+M group, n=14) were injected into the thrombus. After 28 days, histologically, the arterial lumens of the F and M groups were partly filled with fibrous tissues, whereas in the F+M group organization was almost completed and luminal sizes diminished. Immunohistochemical staining demonstrated that α-smooth muscle actin-positive cells were more abundantly contained in the organized area of the F+M group than in the other groups. We also analyzed cellular function in vitro with immunofluorescence; coculture of fibroblasts and myoblasts showed that the fraction of α-smooth muscle actin-positive fibroblasts increased. This phenomenon accounts for the rapid organization of thrombus in the F+M group in vivo.

Conclusions— Cell transplantation accelerated thrombus organization. Especially, myoblasts enhanced differentiation of fibroblasts into myofibroblasts, contributing to rapid thrombus organization. Cell transplantation into unorganized spaces seems applicable to endovascular treatment of aneurysms.

Aortic aneurysm repair with endovascular grafts: developing a graft surveillance program

The objective of this study was to describe the development of a comprehensive surveillance program for monitoring the long-term follow-up of endoluminal stent graft (ELG) patients. Despite high procedural success rates, ELG patients remain at ongoing risk for aneurysm sac expansion, rupture, and other adverse events that make long-term surveillance imperative. As they perform more ELG, practitioners face increased logistical difficulty performing appropriate patient follow-up. A computer-based data ELG registry was created using Epi Info, a program developed by the Centers for Disease Control and Prevention that enables users to design a data entry form, enter data, and perform statistical analyses. The database has been used to track 259 patients (214 men and 45 women) who underwent ELG between November 1999 and October 2003. One-year follow-up was available for 182 patients, 2-year follow-up for 104 patients, and 3-year surveillance data for 40 patients, which represent follow-up rates of 89.6%, 78.8%, and 61.5%, respectively. There were 25 late deaths. The Kaplan-Meier estimate for 1-year survival was 92.5%. Twenty-one patients underwent 24 secondary angiographic procedures at a mean 8.6 +/- 10.3 months (range, 1-37.6) after stent-graft repair. No mortality was observed in association with a secondary intervention. There were no late conversions to open aneurysm repair. The Kaplan-Meier estimate for freedom from secondary intervention for all patients at 1 year was 91.0%. A computer-based registry facilitates appropriate and timely patient follow-up and may improve the long-term outcome from ELG.

Endovascular Stent-Graft Treatment for Thoracic Aortic Aneurysms: Short- to Midterm Results

PURPOSE

To evaluate short- and midterm results of the endovascular repair of thoracic aortic aneurysm (TAA) with the use of custom-made stent-grafts.

MATERIALS AND METHODS

Between May 1997 and May 2003, 40 patients with TAA (26 degenerative/atherosclerotic, seven dissection-related, three traumatic, two mycotic, one anastomotic, and one penetrating ulcer) underwent endovascular stent-graft placement. The mean age of the patients (29 male and 11 female) was 67.2 years. Twenty-four of the 40 patients (60%) were judged not to be good candidates for conventional open repair. Stent-graft placement was performed in the angiography suite with general anesthesia and transient cardiac arrest or induced hypotension. Custom-made stent-grafts were used in all patients. Four of the 40 patients (10%) underwent preliminary extra-anatomic bypass surgery to provide a sufficiently long landing zone. The mean follow-up period was 16.7 months (range, 1-65 months).

RESULTS

The technical success rate was 97.5% and the early mortality rate was 2.5% (one out of 40 patients). There were four late deaths (two procedure-related). Survival rates were 84.2%+/-6.6% at 1 year and 84.2%+/-6.6% at 2 years. Survival rates were not significantly different between surgical candidates and non-surgical candidates (P =.423). Intraprocedural complications included access artery complications in nine patients and bleeding in three patients. Postoperative complications included early aneurysmal expansion in one patient, pneumonia in one patient, wound infection in one patient, stroke in three patients, paraplegia in one patient, respiratory insufficiency in two patients, aortoesophageal fistula in one patient, and late aneurysmal expansion in three patients. The rates of freedom from first additional intervention were 91.0%+/-6.7% at 1 year and 74.5%+/-11.9% at 2 years. The rates of freedom from second additional intervention was 100% at 2 years. The rates of freedom from treatment failure were 84.7%+/-7.6% at 1 year and 69.3%+/-11.6% at 2 years.

CONCLUSION

Endovascular repair of TAA with a custom-made stent-graft is a safe and effective alternative to open repair and continues to play an important role. However, careful follow-up is mandatory to manage complications.

Volume regression of abdominal aortic aneurysms and its relation to successful endoluminal exclusion

OBJECTIVES

Evaluating the success of endoluminal repair of abdominal aortic aneurysms (AAAs) is frequently based on diameter measurements and determining the presence of endoleaks. The use of three-dimensional volumetric data and observation of morphologic changes in the aneurysm and device have been proposed to be more appropriate for postdeployment surveillance. The purpose of this study was to analyze the long-term volumetric and morphologic data of 161 patients who underwent endovascular AAA exclusion and to assess the utility of volume measurements for determining successful AAA repair.

METHODS

Patients with spiral computed tomography scans obtained preoperatively, within the first postoperative month, at 6 months, and annually thereafter, were included in this analysis. Computerized interactive three-dimensional reconstruction of each AAA scan was performed. Total aneurysm sac volume was measured at each time interval (mean preoperative volume 169.0 +/- 78.5 mL), and the significance of volume changes was determined by mixed linear modeling, a form of repeated measures analysis, to account for longitudinal data clustered at the individual level. Sixty-two patients (38%) developed endoleaks at some time during follow-up-15 type I leaks, 45 type II leaks, and 2 type III leaks. The patients with type I and type III leaks were treated with cuffs, and the type II leaks were treated either with observation, side-branch embolization, or required open conversion.

RESULTS

Aneurysm sac volume increased slightly at 1-month follow-up (+3.3%), and then decreased steadily to -12.9% at 5 years (P <.0001). This effect remained unchanged after controlling for the three device types used in our study population. Patients who did not exhibit an endoleak (n = 99) showed a significant decrease in aneurysm volume across the entire follow-up duration when compared with those who did exhibit an endoleak (n = 62) (P <.0001). The presence of a 10% or greater decrease in volume at 6 months demonstrated a sensitivity of 64%, a specificity of 95%, a positive predictive value of 95%, a negative predictive value of 62%, and an accuracy of 75% for predicting primary clinical success defined by successful deployment of the device; freedom from aneurysm- or procedure-related death; freedom from endoleak, rupture, migration, or device malfunction; or conversion to open repair.

CONCLUSIONS

Volumetric analysis may be used to predict successful endoluminal exclusion of AAAs. Volume regression appears to be device-independent and should be expected in most clinically successful cases. The presence of volume increases in the first 6 months is suspicious for an endoleak that is pressurizing the aneurysm sac and heralds the need for closer evaluation and possible intervention. A volume decrease of 10% or greater at 6 months and continuing regression over time is associated with successful endovascular repair.

Endoluminal AAA repair using intravascular ultrasound for graft planning and deployment: a 2-year community-based experience

PURPOSE

To examine the effectiveness of intravascular ultrasound (IVUS) and digital subtraction angiography (DSA) for preoperative planning and intraoperative deployment of stent-grafts to treat abdominal aortic aneurysms.

METHODS

One hundred seventy patients (143 men; mean age 73.6+/-7.2 years, range 51-89) underwent successful DSA and IVUS to determine suitability for stent-graft repair. Patients subsequently received the AneuRx (n=157) or Ancure (n=13) device; intraprocedural IVUS was used to survey the proximal endograft for proper apposition to the aortic wall.

RESULTS

Reliable preoperative IVUS measurements were obtained in all patients. Plaque morphology was assessed in 140 (82.3%) aortic necks; in 36 (25.7%), preoperative IVUS showed high-grade atherosclerotic plaque in the nonaneurysmal abdominal aortic neck. The procedure was successful in 168 (98.8%) cases (1 [0.6%] acute conversion and 1 access failure). There were 2 (1.2%) periprocedural deaths related to bowel ischemia. Four (2.3%) patients developed graft occlusion/kinking and 2 (1.2%) developed renal failure requiring dialysis within 30 days. Multivariate logistic regression analysis revealed that female gender (p=0.0247), a short nonaneurysmal aortic neck (p=0.0185), and presence of high-grade atherosclerotic plaque (p=0.0185) correlated with major acute complications. Over a mean 10.4-month follow-up (range 1-25), 11 patients died of unrelated causes; there was no known AAA rupture or device failure. The Kaplan-Meier estimate of survival at 1 year was 91.0%+/-2.8%. Sixteen (9.4%) patients underwent 17 secondary procedures for endoleak or graft limb occlusion at a mean 5.4 months after stent-graft repair (freedom from secondary intervention at 1 year 86.5%+/-3.2%).

CONCLUSIONS

Our findings suggest that IVUS may identify patients at increased risk of major adverse complications following endovascular repair. The combination of IVUS and DSA for endoluminal stent-graft planning and placement provides excellent short- and mid-term patient outcomes.

Does the type of endograft affect AAA volume change after endovascular aneurysm repair?

PURPOSE

To compare thrombus volume changes in a longitudinal study over 2 years after endovascular aneurysm repair using the Ancure and Excluder endografts.

METHODS

In 2 institutions, all consecutive patients treated with a bifurcated Ancure or Excluder endograft were included in this retrospective comparison of computed tomographic angiography (CTA) data recorded and stored to disk postoperatively and at the 12 (12M) and 24-month (24M) follow-up examinations. In one institution, among 45 Ancure endograft patients, 35 (group A) had the 3 requisite scans available. In the second institution, 23 (group B) of 36 patients with the Excluder endograft were eligible for analysis. The proportional volume change was calculated at 12M and 24M and compared to the postoperative CT data. More than 10% shrinkage was considered significant.

RESULTS

In both groups, the median absolute volume changed significantly. In group A, significant shrinkage was found in 66% (23/35) at 12M and 74% (26/35) at 24M; in group B, 46% (10/23) had significant shrinkage at 12M as well as at 24M (p=0.027 for the difference between groups A and B at 24M). Statistical analysis of the proportional volume change showed a significant difference between the Ancure and the Excluder devices at 12M (p=0.009) and 24M (p=0.001). Multivariate analysis found aneurysm size (p<0.012) and endograft type (p=0.026) to be independently predictive of the absolute volume change.

CONCLUSIONS

Sac volume shrinkage after endovascular aneurysm repair is less pronounced and less frequent with the Excluder endoprosthesis than with the Ancure endograft.

Elective endovascular stent-graft repair of atherosclerotic thoracic aortic aneurysms: clinical results and midterm follow-up

OBJECTIVE

The purpose of this study was to evaluate the clinical and midterm results after endovascular treatment of atherosclerotic thoracic aortic aneurysms.

MATERIALS AND METHODS

Twenty-eight consecutive patients who were 53-82 years old (mean age, 71.6 years) were treated with a commercially available endoprosthesis. Subclavian transposition or bypass surgery was performed before the procedure in eight patients. Size dynamics of the aneurysms were analyzed on the basis of diameter and thrombus volume measurements obtained on three-dimensional CT reconstructions before hospital discharge (n = 22) and at the 1-year (n = 22), 2-year (n = 12), and 3-year (n = 5) follow-ups.

RESULTS

The technical success rate was 100%. There was no 30-day mortality. None of the patients had symptoms due to spinal cord ischemia. The survival rate at 1, 2, and 3 years was 96.1%, 90.9%, and 80.2%, respectively. During the perioperative period, patients presented with leukocytosis (37%), fever (36%), elevated C-reactive protein value (92%), pleural effusion (50%), and periaortic atelectasis (41%). Three early type I endoleaks sealed spontaneously. Three early type II endoleaks persisted over time, and one late type II endoleak was detected. In patients with type II endoleaks, thrombus volume of the aneurysms was constant (n = 2) or increased (n = 2). In patients without endoleaks, mean thrombus volume decreased (-53.2 +/- 56.8 mL, -40%) significantly (p = 0.001) during the first year. There was no significant interval decrease between the 1- and 2-year follow-ups (mean, -2.4 mL, p = 0.92) and between the 2- and 3-year follow-ups (mean, -0.4 mL, p = 0.68).

CONCLUSION

Endovascular treatment of atherosclerotic thoracic aortic aneurysms may result in a substantial reduction of the aneurysm sac in patients without endoleaks.