Impact of thoracic endovascular aortic repair timing on outcomes after uncomplicated type B aortic dissection in the Society for Vascular Surgery Vascular Quality Initiative postapproval project for dissection.

OBJECTIVE: The timing of thoracic endovascular aortic repair (TEVAR) after the onset of uncomplicated acute type B aortic dissection (uTBAD) remains controversial. The objective of this study was to evaluate the Society for Vascular Surgery Vascular Quality Initiative (VQI) postapproval study (VQI PAS) data for the impact of TEVAR timing for uTBAD on early and late outcomes, including mortality, procedural complications, and long-term reintervention. METHODS: The VQI PAS used for this analysis includes a total of 606 patients. Patients with uTBAD (defined as those without rupture or malperfusion) exclusive of cases categorized as emergent (N = 206) were divided into groups defined by the Society for Vascular Surgery/Society of Thoracic Surgeons reporting guidelines based on the timing of treatment after the onset of dissection: within 24 hours (N = 8), 1 to 14 days (N = 121), and 15 to 90 days (N = 77). Univariate and multivariable analysis were used to determine differences between timing groups for postoperative mortality, in-hospital complications, and reintervention. RESULTS: Demographics and comorbid conditions were very similar across the 3 TEVAR timing groups. Notable differences included a higher prevalence of baseline elevated creatinine (>1.8 mg/dL)/chronic end-stage renal disease and designation as "urgent" in the <24-hour group, as well as a higher rate of preoperative ß-blocker therapy in the 1- to 14-day group. Postoperative stroke, congestive heart failure, and renal ischemia were more common in the <24-hour group without an increase in mortality. Unadjusted 30-day mortality across groups was lowest in the early TEVAR group (0%, 3.3%, and 5.2%; P = .68), as was 1-year mortality (0%, 8.3%, and 18.2%; P = .06), although not statistically different at any time point. Reintervention out to 3 years was not different between the groups. Multivariable analysis demonstrated the need for a postoperative therapeutic lumbar drain to be the only a predictive risk factor for mortality (hazard ratio = 7.595, 95% confidence interval: 1.730-33.337, P = .007). When further subdivided into patients treated 1 to 7 days or 8 to 14 days after dissection, findings were similar. CONCLUSIONS: Patients with uTBAD treated within 24 hours were unusual (N = 8), too small for valid statistical comparison, and likely represent a high-risk subgroup, which is manifested in a higher risk of complications. Although there was a trend toward improved survival in the acute (1- to 14-day) phase, outcomes did not differ compared with the subacute (15- to 90-day) phase with relation to early mortality, postoperative complications, or 1-year survival. These data suggest that the proper selection of patients for early TEVAR can result in equivalent survival and early outcomes.

Results of the North American Complex Abdominal Aortic Debranching (NACAAD) Registry.

BACKGROUND: Hybrid debranching repair of pararenal and thoracoabdominal aortic aneurysms was initially designed as a better alternative to standard open repair, addressing the limitations of endovascular repair involving the visceral aorta. We reviewed the collective outcomes of hybrid debranching repairs using extra-anatomic, open surgical debranching of the renal-mesenteric arteries, followed by endovascular aortic stenting. METHODS: Data from patients who underwent hybrid repair in 14 North American institutions during 10 years were retrospectively reviewed. Society of Vascular Surgery scores were used to assess comorbidity risk. Early and late outcomes, including mortality, morbidity, reintervention, and patency were analyzed. RESULTS: A total of 208 patients (118 male; mean age, 71±8 years old) were treated by hybrid repair with extraanatomic reconstruction of 657 renal and mesenteric arteries (mean 3.2 vessels/patient). Mean aneurysm diameter was 6.6±1.3 cm. Thoracoabdominal aortic aneurysms were identified in 163 (78%) patients and pararenal aneurysms in 45 (22%). A single-stage repair was performed in 92 (44%) patients. The iliac arteries were the most common source of inflow (n=132; 63%), and most (n=150; 72%) had 3 or more bypasses. There were 30 (14%) early deaths, ranging widely across sites (0%-21%). A Society of Vascular Surgery comorbidity score >15 was the primary predictor of early mortality (P<0.01), whereas mortality was 3% in a score ≤9. Early complications occurred in 140 (73%) patients and included respiratory complications in 45 patients (22%) and spinal cord ischemia in 22 (11%), of whom 10 (45%) fully recovered. At 5 years, survival was 61±5%, primary graft patency was 90±2%, and secondary patency was 93±2%. The most significant predictor of late mortality was renal insufficiency (P<0.0001). CONCLUSIONS: Mortality after hybrid repair and visceral debranching is highly variable by center, but strongly affected by preoperative comorbidities and the centers' experience with the technique. With excellent graft patency at 5 years, the outcomes of hybrid repair done at centers of excellence and in carefully selected patients may be comparable (or better) than traditional open or even totally endovascular approaches. However, in patients already considered as high-risk for surgery, it may not offer better outcomes.

Retrograde type A dissection in the Vascular Quality Initiative thoracic endovascular aortic repair for dissection postapproval project.

BACKGROUND: Retrograde dissection (RD) can be a serious complication after thoracic endovascular aortic repair (TEVAR), with retrograde type A dissection (RTAD) particularly life-threatening. Prior studies have suggested that treatment timing, anatomic characteristics, device selection, and procedural conduct of TEVAR performed for type B aortic dissection could mitigate the occurrence of RD. The Vascular Quality Initiative TEVAR for Dissection Registry is an ongoing project meant to satisfy Food and Drug Administration requirements for postmarket approval surveillance of the Gore conformable TAG thoracic endoprosthesis (W.L. Gore & Associates, Flagstaff, Ariz), Medtronic Valiant thoracic stent graft (Medtronic, Santa Rosa, Calif), and Cook Medical dissection devices (Cook Medical, Bloomington, Ind) and provides a unique source of evaluation for RTAD in a prospectively collected real-world registry. METHODS: A total of 588 consecutive patients at 49 institutions had undergone TEVAR for acute (<30 days; n = 336) and chronic (≥30 days; n = 252) type B aortic dissection were included. The occurrence of RD as reported by the participating centers and de-identified source documents were reviewed and confirmed independently by two of us (A.W.B. and G.W.). The demographics, procedural and device data, and anatomic considerations were evaluated, and the devices were grouped in a de-identified manner as Gore, Medtronic, and other. RESULTS: The mean follow-up was 889 days (median, 658 days), and 408 patients had completed follow-up data available for >1 year. A total of 19 patients with RD (3.2%) were identified, 9 of whom had been treated for acute and 10 for chronic dissection, a 2.7% and 4.0% incidence, respectively (P = .48, acute vs chronic). Of the 19 RD cases, 15 were RTAD, 6 after treatment of acute and 9 after treatment of chronic dissection, a 1.8% and 3.6% incidence, respectively (P = .19, acute vs chronic). Five cases of RD had occurred intraoperatively (four of which were RTAD). The median time to RD and RTAD was 62 and 69 days, respectively (range, 0 to 1600 days). Of the 15 patients with RTAD, 12 had undergone surgical repair and 2 had not undergone repair; the treatment of one was unknown. The overall mortality was 33.3% (5 of 15). The factors associated with RTAD included more extensive dissection (mean, 5.6 zones without RTAD vs 8.5 zones with RTAD; P = .001), female sex (28.3% female without RTAD vs 53.3% with RTAD; P = .04), and non-White race (62.7% White without RTAD vs 33.3% White with RTAD; P = .05). Mean oversizing was not significantly different for those without RTAD compared with that for those with RTAD (14.0% vs 14.2%; P = .92). The device type was anonymized in this project; however, we found no significant differences between the Gore, Medtronic, and all other devices. CONCLUSIONS: The rate of RD in the present real-world postapproval project was consistent with that from previously reported studies, including highly controlled pivotal studies. Device type was not predictive of RD, and the newly identified risk factors for RTAD include more extensive dissection and a trend toward a greater risk for female sex and non-White race.

Procedure-Associated Costs and Mid-Term Outcomes of Endovascular Zone 0 and Zone 1 Aortic Arch Repair.

BACKGROUND: Thoracic endovascular aortic repair (TEVAR) of proximal aortic arch pathology provides a less-invasive treatment option for high-risk patients ineligible for open arch reconstruction. However, the fiscal impact of these techniques remains unclear. Therefore, our objective was to characterize the mid-term outcomes after Zone 0 and Zone 1 TEVAR and describe the associated technical costs, revenues, and net margins at a single tertiary medical center. METHODS: We examined all patients who underwent TEVAR between April 2011 and August 2019 via retrospective chart review. Patients were categorized by proximal endograft extent to identify Zone 0 or Zone 1 repairs. Procedural characteristics and outcomes were described. Technical costs, revenues, and margins were obtained from the hospital finance department. RESULTS: We identified 10 patients (6 Zone 0, 4 Zone 1) who were denied open arch reconstruction. Patients were predominantly female (n = 8; 80%) and the mean age was 72.8 ± 5.5 years. TEVAR was performed in 5 asymptomatic patients, urgently in 3 symptomatic patients, and emergently in 2 ruptured patients. TEVAR plus extra-anatomic bypass was performed in 4 patients. Another 4 patients also received parallel stent-grafting while 1 patient received a branched thoracic endograft and yet another an in-situ laser fenestration followed by branch stent grafting. Within the 30-day postoperative period, 1 patient experienced stroke and 1 patient died. Bypass and branch vessel patency were 100% through the duration of follow-up (mean 19.3 months). Mean total technical cost associated with all procedures or repair stages was $105,164 ± $59,338 while mean net technical margin was -$25,055 ± $18,746. The net technical margin was negative for 9 patients. CONCLUSIONS: Endovascular repair of the proximal aortic arch is associated with good mid-term outcomes in patients considered too high-risk for open repair. However, reimbursement does not adequately cover treatment cost, with net technical margins being negative in nearly all cases. To remain financially sustainable, efforts should be made to both optimize aortic arch TEVAR delivery as well as advocate for reimbursement commensurate with associated costs.

National trends in open surgical, endovascular, and branched-fenestrated endovascular aortic aneurysm repair in Medicare patients.

BACKGROUND: Open repair effectively prevents rupture for patients with abdominal aortic aneurysm (AAA) and is commonly studied as a metric reflecting hospital and surgeon expertise in cardiovascular care. However, given recent advances in endovascular aneurysm repair (EVAR), such as branched-fenestrated EVAR, it is unknown how commonly open surgical repair is still used in everyday practice. METHODS: We analyzed trends in open AAA repair, EVAR, and branched-fenestrated EVAR for AAA in Medicare beneficiaries from 2003 to 2013. We used Medicare Part B claims to ascertain counts of these repair types annually during the study period. We assessed regional and national trends in characteristics of the patients and procedure volume. RESULTS: Between 2003 and 2013, the total number of AAA repairs performed in fee-for-service Medicare patients declined by 26% from 31,582 to 23,421 (P < .001), after a peak number of 32,540 was performed in 2005 (28% decline since 2005). The number of open AAA repairs steadily declined by a total of 76%, from 20,533 in 2003 to 4916 in 2013 (P < .001). Whereas the number of EVARs increased from 11,049 in 2003 to 19,247 in 2011 (P < .001), it has since declined a total of 15% to only 16,362 repairs in 2013 (P < .001). After its introduction in 2011, the number of branched-fenestrated EVAR cases continuously rose from 335 procedures in 2011 to 2143 procedures in 2013 (P < .001). By 2013, virtually all hospital referral regions in the United States had rates of open AAA repair that would have been in the lowest quintile of volume in 2003. CONCLUSIONS: The number of open AAA repairs fell by nearly 80% during the last decade, whereas traditional EVAR declined slightly and branched-fenestrated EVAR rapidly disseminated into national practice. These results suggest that open AAA repair is now performed too infrequently to be used as a metric in the assessment of hospital and surgeon quality in cardiovascular care. Furthermore, surgical training paradigms will need to reflect the changing dynamics necessary to ensure that surgeons and interventionists can safely perform these high-risk surgical procedures.

Carotid endarterectomy should not be based on consensus statement duplex velocity criteria.

OBJECTIVE: Randomized trials support carotid endarterectomy (CEA) in asymptomatic patients with ≥60% internal carotid artery (ICA) stenosis. The widely referenced Society for Radiologists in Ultrasound Consensus Statement on carotid duplex ultrasound (CDUS) imaging indicates that an ICA peak systolic velocity (PSV) ≥230 cm/s corresponds to a ≥70% ICA stenosis, leading to the potential conclusion that asymptomatic patients with an ICA PSV ≥230 cm/s would benefit from CEA. Our goal was to determine the natural history stroke risk of asymptomatic patients who might have undergone CEA based on consensus statement PSV of ≥230 cm/s but instead were treated medically based on more conservative CDUS imaging criteria. METHODS: All patients who underwent CDUS imaging at our institution during 2009 were retrospectively reviewed. The year 2009 was chosen to ensure extended follow-up. Asymptomatic patients were included if their ICA PSV was ≥230 cm/s but less than what our laboratory considers a ≥80% stenosis by CDUS imaging (PSV ≥430 cm/s, end-diastolic velocity ≥151 cm/s, or ICA/common carotid artery PSV ratio ≥7.5). Study end points included freedom from transient ischemic attack (TIA), freedom from any stroke, freedom from carotid-etiology stroke, and freedom from revascularization. RESULTS: Criteria for review were met by 327 patients. Mean follow-up was 4.3 years, with 85% of patients having >3-year follow-up. Four unheralded strokes occurred during follow-up at <1, 17, 25, and 30 months that were potentially attributable to the index carotid artery. Ipsilateral TIA occurred in 17 patients. An additional 12 strokes occurred that appeared unrelated to ipsilateral carotid disease, including hemorrhagic events, contralateral, and cerebellar strokes. Revascularization was undertaken in 59 patients, 1 for stroke, 12 for TIA, and 46 for asymptomatic disease. Actuarial freedom from carotid-etiology stroke was 99.7%, 98.4%, and 98.4% at 1, 3, and 5 years, respectively. Freedom from TIA was 98%, 96%, and 95%, freedom from any stroke was 99%, 96%, and 93%, and freedom from revascularization was 95%, 86%, and 81% at 1, 3, and 5 years, respectively. CONCLUSIONS: Patients with intermediate asymptomatic carotid stenosis (ICA PSV 230-429 cm/s) do well with medical therapy when carefully monitored and intervened upon using conservative CDUS criteria. Furthermore, a substantial number of patients would undergo unnecessary CEA if consensus statement CDUS thresholds are used to recommend surgery. Current velocity threshold recommendations should be re-evaluated, with potentially important implications for upcoming clinical trials.

Five-year outcomes of the PYTHAGORAS U.S. clinical trial of the Aorfix endograft for endovascular aneurysm repair in patients with highly angulated aortic necks.

OBJECTIVE: Early and midterm outcomes of the Prospective Aneurysm Trial: High Angle Aorfix Bifurcated Stent Graft (PYTHAGORAS) trial in patients with highly angulated aortic necks (≥60 degrees) have already been published and shown comparable outcomes to other endografts in normal anatomy. Herein, we present the long-term outcomes of the PYTHAGORAS trial of Aorfix (Lombard Medical, Irvine, Calif) for patients with highly angulated aortic neck anatomy. METHODS: The Aorfix endograft is a highly conformable nitinol/polyester device designed for transrenal fixation. The U.S. trial enrolled 218 patients and observed all patients at 1 month, 6 months, and 12 months and then annually for a total of 5 years. Endovascular aneurysm repair (EVAR)-specific complications were compared between the standard-angle (<60 degrees) and highly angulated (≥60 degrees) neck groups at 5 years using standard statistical methods. Kaplan-Meier analysis was performed to evaluate the overall 5-year survival and freedom from aneurysm rupture, aneurysm-related mortality, and reintervention. RESULTS: Of the 218 patients enrolled in the trial, there were 67 patients in the standard-angle neck group (I) and 151 patients in the highly angulated neck group (II). Mean proximal neck angle was 45 degrees in group I vs 83 degrees in group II (P < .001). At 5 years, 87% of surviving patients were followed up. The 5-year EVAR-specific results showed no type I or type III endoleak in either group, 4% migration in group I vs 3% in group II, and 4% sac expansion in group I vs 15.0% in group II (P ≥ .27). The 5-year freedom from all-cause mortality was 69% (73% in group I vs 68% in group II; P = .43); from aneurysm-related mortality, 96% (99% vs 95%; P = .44); from aneurysm rupture, 99% (99% vs 99%; P = 1.0); and from device-related secondary intervention, 83% (88% vs 80%; P = .18). None of these differed between groups. CONCLUSIONS: The U.S. PYTHAGORAS trial of the Aorfix endograft is the first EVAR clinical trial to include a majority of highly angulated (≥60 degrees) infrarenal aortic necks and is the first to produce evidence after 5 years of implantation. Despite predictors of worse short- and long-term outcomes, pertinent outcomes were better than or similar to those of trials with less severe anatomy. These results support the use of this "on-label" endovascular option, particularly in patients with highly angulated aortic neck anatomy.

Results of transcaval embolization for sac expansion from type II endoleaks after endovascular aneurysm repair.

OBJECTIVE: Management of type II endoleaks after endovascular aneurysm repair can be problematic. This study reports our experience with a relatively novel strategy to treat this complication, transcaval coil embolization (TCCE) of the aneurysm sac. METHODS: We reviewed 29 consecutive patients undergoing TCCE from 2010 to 2013. Demographics, operative details, and outcomes were assessed. RESULTS: Since 2006, 29 TCCEs have been performed at our institution in 26 patients for sac expansion from type II endoleaks. Patients were male (83%) and former or current smokers (88%), with an average age of 78 ± 7.1 years. TCCE was performed a mean of 4.2 ± 4 years after initial endovascular aneurysm repair. Endoleaks resulted in a mean sac growth of 1.2 ± 1 cm in diameter and 37% ± 32% by volume. Forty-six percent had prior procedures (5 translumbar, 3 transarterial, 3 transcaval, 1 aortic cuff, and 1 iliac limb extension). Two patients had no flow identified in the aneurysm sac after puncture was successful, and one was found to have a hygroma rather than arterial flow. An additional two patients had ultimate embolization from sac access between the endograft iliac limb and arterial wall after transcaval puncture failed, for a 90% procedural success (83% for transcaval technical success). Mean fluoroscopy time was 27 ± 13 minutes with 29 ± 21 mL of contrast material used and a median of 10 coils per case. Additional adjuncts included thrombin injection (17%), intravascular ultrasound (14%), sac pressure measurements (28%), and on-table integrated computed tomography (17%). Median length of stay was 1 day (range, 0-5 days). There were no procedural adverse events. Reintervention was required in five cases (three repeated TCCEs, two graft relinings). One-year freedom from reintervention was 95%. At a mean 16.5 months of follow-up, 70% experienced no further endoleak and had stable or decreasing sac diameters. There have been no ruptures during follow-up. CONCLUSIONS: In this series, TCCE for treatment of aneurysm enlargement due to type II endoleaks was safe and relatively effective despite prior failed interventions in nearly half of the cases. TCCE is a useful alternative in cases in which the anatomy makes other approaches difficult or impossible.

National trends in utilization, mortality, and survival after repair of type B aortic dissection in the Medicare population.

OBJECTIVE: The application of thoracic endovascular aortic repair (TEVAR) has changed treatment paradigms for thoracic aortic disease. We sought to better define specific treatment patterns and outcomes for type B aortic dissection treated with TEVAR or open surgical repair (OSR). METHODS: Medicare patients undergoing type B thoracic aortic dissection repair (2000-2010) were identified by use of a validated International Classification of Diseases, Ninth Revision diagnostic and procedural code-based algorithm. Trends in utilization were analyzed by procedure type (OSR vs TEVAR), and patterns in patient characteristics and outcomes were examined. RESULTS: Total thoracic aortic dissection repairs increased by 21% between 2000 and 2010 (2.5 to 3 per 100,000 Medicare patients; P = .001). A concomitant increase in TEVAR was seen during the same interval (0.03 to 0.8 per 100,000; P < .001). By 2010, TEVAR represented 27% of all repairs. TEVAR patients had higher rates of comorbid congestive heart failure (12% vs 9%; P < .001), chronic obstructive pulmonary disease (17% vs 10%; P < .001), diabetes (8% vs 5%; P < .001), and chronic renal failure (8% vs 3%; P < .001) compared with OSR patients. For all repairs, patient comorbidity burden increased over time (mean Charlson comorbidity score of 0.79 in 2000, 1.10 in 2010; P = .04). During this same interval, in-hospital mortality rates declined from 47% to 23% (P < .001), a trend seen in both TEVAR and OSR patients. Whereas in-hospital mortality rates and 3-year survival were similar between patients selected for TEVAR and OSR, there was a trend toward women having slightly lower 3-year survival after TEVAR (60% women vs 63% men; P = .07). CONCLUSIONS: Surgical treatment of type B aortic dissection has increased over time, reflecting an increase in the utilization of TEVAR. Overall, type B dissection repairs are currently performed at lower mortality risk in patients with more comorbidities.

Early discharge does not increase readmission or mortality after high-risk vascular surgery.

PURPOSE: Clinical pathways aimed at reducing hospital length of stay following vascular surgery have been broadly implemented to reduce costs. However, early hospital discharge may adversely affect the risk of readmission or mortality. To address this question, we examined the relationship between early discharge and 30-day outcomes among patients undergoing a high-risk vascular surgery procedure, thoracic aortic aneurysm (TAA) repair. METHODS: Using Medicare claims from 2000 to 2007, we identified all patients who were discharged home following elective thoracic endovascular aneurysm repair (TEVAR) and open repair for nonruptured TAAs. For each procedure, we examined the correlation between early discharge (<3 days for TEVAR, <7 days for open TAA repair) and 30-day readmission, 30-day mortality, and hospital costs. Predictors of readmission were evaluated using logistic regression models controlling for patient comorbidities, perioperative complications, and discharge location. RESULTS: Our sample included 9764 patients, of which 7850 (80%) underwent open TAA repair, and 1914 (20%) underwent TEVAR. Patients discharged to home early were more likely to be female (66% early vs 56% late), Caucasian (94% early vs 91% late), younger (73 years early vs 74 years late), and have fewer comorbidities (mean Charlson score: 0.7 early vs 1.0 late) than patients discharged home late (all P < .01). As compared with patients who were discharged late, patients discharged home early following uncomplicated open TAA repair and TEVAR had significantly lower 30-day readmission rates ([open: 17% vs 24%; P < .001] [TEVAR: 12% vs 23%; P < .001]) and hospital costs ([open: $73,061 vs $136,480; P < .001] [TEVAR: $58,667 vs $128,478; P < .001]), without an observed increase in 30-day postdischarge mortality. In multivariable analysis, early hospital discharge was associated with a significantly lower likelihood of readmission following both open TAA repair (odds ratio, 0.70; 95% confidence interval, 0.57-0.85; P < .001) and TEVAR (odds ratio, 0.57; 95% confidence interval, 0.38-0.85; P < .01) procedures. CONCLUSIONS: Discharging patients home early following uncomplicated TEVAR or open TAA repair is associated with reduced hospital costs without adversely impacting 30-day readmission or mortality rates. These data support the safety and cost-effectiveness of programs aimed at early hospital discharge in selected vascular surgery patients.

Survival after open versus endovascular thoracic aortic aneurysm repair in an observational study of the Medicare population.

BACKGROUND: The goal of this study was to describe short- and long-term survival of patients with descending thoracic aortic aneurysms (TAAs) after open and endovascular repair (TEVAR). METHODS AND RESULTS: Using Medicare claims from 1998 to 2007, we analyzed patients who underwent repair of intact and ruptured TAA, identified from a combination of procedural and diagnostic International Classification of Disease, ninth revision, codes. Our main outcome measure was mortality, defined as perioperative mortality (death occurring before hospital discharge or within 30 days), and 5-year survival, from life-table analysis. We examined outcomes across repair type (open repair or TEVAR) in crude, adjusted (for age, sex, race, procedure year, and Charlson comorbidity score), and propensity-matched cohorts. Overall, we studied 12 573 Medicare patients who underwent open repair and 2732 patients who underwent TEVAR. Perioperative mortality was lower in patients undergoing TEVAR compared with open repair for both intact (6.1% versus 7.1%; P=0.07) and ruptured (28% versus 46%; P<0.0001) TAA. However, patients with intact TAA selected for TEVAR had significantly worse survival than open patients at 1 year (87% for open, 82% for TEVAR; P=0.001) and 5 years (72% for open; 62% for TEVAR; P=0.001). Furthermore, in adjusted and propensity-matched cohorts, patients selected for TEVAR had worse 5-year survival than patients selected for open repair. CONCLUSIONS: Although perioperative mortality is lower with TEVAR, Medicare patients selected for TEVAR have worse long-term survival than patients selected for open repair. The results of this observational study suggest that higher-risk patients are being offered TEVAR and that some do not benefit on the basis of long-term survival. Future work is needed to identify TEVAR candidates unlikely to benefit from repair.

The influence of gender and aortic aneurysm size on eligibility for endovascular abdominal aortic aneurysm repair.

OBJECTIVES: The purpose of this study was to compare the eligibility of men and women with infrarenal abdominal aortic aneurysms (AAAs) for on-label endovascular aneurysm repair (EVAR) as part of the clinician-Food & Drug Administration (FDA) collaborative effort, the Characterization of Human Aortic Anatomy Project (CHAP). METHODS: Computed tomography (CT) scans with 3D reconstruction from a single institution obtained between July 1996 and December 2009, including standardized measurements by a blinded third-party (M2S, West Lebanon, NH) were examined. For inclusion, abdominal aortic aneurysm (AAA) had to be infrarenal, unrepaired, and >5 cm, or 4 cm to 5 cm if the orthogonal sac diameter was more than twice the aortic diameter at the renal level. Scans were included regardless of subsequent EVAR, open repair, or lack of treatment. One thousand sixty-three unique, unrepaired AAAs were analyzed. RESULTS: Neck length, diameter, and angulation differ for women (P < .001) even after adjustment for patient age and AAA size. EVAR eligibility based on device Instructions for Use (IFU) criterion is affected by gender. Neck length <15 mm was found in 47% of men and 63% of women. Neck angulation exceeding 60 degrees was found in 12% of men and 26% of women. Minimum iliac diameter of 6 mm was found in 35% of men and 55% of women. Only 32% of men and 12% of women met all three neck criterion and had iliac lumen diameters >6 mm. Logistic regression modeling shows that older patient age (odds ratio [OR], 0.84 per decade), increased aneurysm diameter (OR, 0.70 per cm), and female gender (OR, 0.4) are each independently associated with decreased odds of meeting all device IFU neck criterion (P < .05). EVAR eligibility by neck criterion does not decline significantly until AAA size exceeds 5.5 cm in women and 6.5 cm in men. CONCLUSION: Women are significantly less likely to meet device IFU criterion for EVAR. Aortic neck criteria and iliac access are important for men and women, but more women than men fail to meet IFU criterion. Devices that accommodate shorter infrarenal AAA neck length will have the greatest impact on expanding on-label EVAR regardless of gender. Lower profile devices and those that accommodate higher neck angulation are expected to expand EVAR eligibility further for women. EVAR eligibility is unlikely to be lost as AAAs enlarge to 5.5 cm in women and 6.5 cm in men. Observation of small AAAs until they reach the standard threshold size for repair should not compromise EVAR eligibility.

Impact of dynamic computed tomographic angiography on endograft sizing for endovascular aneurysm repair.

PURPOSE: To quantify dynamic changes in aortoiliac dimensions using dynamic electrocardiographically (ECG)-gated computed tomographic angiography (CTA) and to investigate any potential impact on preoperative endograft sizing in relation to observer variability. METHODS: Dynamic ECG-gated CTA was performed in 18 patients with abdominal aortic aneurysms. Postprocessing resulted in 11 datasets per patient: 1 static CTA and 10 dynamic CTA series. Vessel diameter, length, and angulation were measured for all phases of the cardiac cycle. The differences between diastolic and systolic aneurysm dimensions were analyzed for significance using paired t tests. To assess intraobserver variability, 20 randomly selected datasets were analyzed twice. Intraobserver repeatability coefficients (RC) were calculated using Bland-Altman analysis. RESULTS: Mean aortic diameter at the proximal neck was 21.4+/-3.0 mm at diastole and 23.2+/-2.9 mm at systole, a mean increase of 1.8+/-0.4 mm (8.5%, p<0.01). The RC for the aortic diameter at the level of the proximal aneurysm neck was 1.9 mm (8.9%). At the distal sealing zones, the mean increase in diameter was 1.7+/-0.3 mm (14.1%, p<0.01) for the right and 1.8+/-0.5 mm (14.2%, p<0.01) for the left common iliac artery (CIA). At both distal sealing zones, the mean increase in CIA diameter exceeded the RC (10.0% for the right CIA and 12.6% for the left CIA). CONCLUSION: The observed changes in aneurysm dimension during the cardiac cycle are small and in the range of intraobserver variability, so dynamic changes in proximal aneurysm neck diameter and aneurysm length likely have little impact on preoperative endograft selection. However, changes in diameter at the distal sealing zones may be relevant to sizing, so distal oversizing of up to 20% should be considered to prevent distal type I endoleak.

In-vivo imaging of changes in abdominal aortic aneurysm thrombus volume during the cardiac cycle.

PURPOSE: To evaluate in-vivo thrombus compressibility in abdominal aortic aneurysms (AAAs) to hopefully shed light on the biomechanical importance of intraluminal thrombus. METHODS: Dynamic electrocardiographically-gated computed tomographic angiography was performed in 17 AAA patients (15 men; mean age 73 years, range 69-76): 11 scheduled for surgical repair and 6 under routine surveillance. The volumes of intraluminal thrombus, the lumen, and the total aneurysm were quantified for each phase of the cardiac cycle. Thrombus compressibility was defined as the percent change in thrombus volume between diastole and peak systole. Continuous data are presented as medians and interquartile ranges (IQR). RESULTS: A substantial interpatient variability was observed in thrombus compressibility, ranging from 0.4% to 43.6% (0.2 to 13.5 mL, respectively). Both thrombus and lumen volumes varied substantially during the cardiac cycle. As lumen volume increased (5.2%, IQR 2.8%-8.8%), thrombus volume decreased (3.0%, IQR 1.0%-4.6%). Total aneurysm volume remained relatively constant (1.3%, IQR 0.4-1.9%). Changes in lumen volume were inversely correlated with changes in thrombus volume (r = -0.73; p = 0.001). CONCLUSION: In-vivo thrombus compressibility varied from patient to patient, and this variation was irrespective of aneurysm size, pulse pressure, and thrombus volume. This suggests that thrombus might act as a biomechanical buffer in some, while it has virtually no effect in others. Whether differences in thrombus compressibility alter the risk of rupture will be the focus of future research.

Original Excluder component overlap from proximal or distal extension during initial repair not correlated with aneurysm sac shrinkage.

OBJECTIVES: The original abdominal Excluder (W.L. Gore & Associates, Flagstaff, Ariz) endoprosthesis has been associated with late aneurysm sac expansion over time from transgraft ultrafiltration of serous fluid. This has been treated by relining the graft with original or low-permeability components. We asked whether additional component overlap of the original graft material resulting from proximal or distal extensions placed at the time of initial repair would influence the rate of late aneurysm sac expansion in the absence of endoleak. METHODS: Computed tomography (CT) scans from subjects (n = 120) receiving the original endoprosthesis from the Excluder pivotal trial were measured for total distance of original graft overlap (including contralateral gate, proximal extension, or distal extension overlap) based on reformatted CT scans. This was compared to change in aneurysm sac diameter and volume (as measured in independent laboratories) at the latest time point available. Patients were omitted if they were missing CT scan data (n = 10), their graft was explanted for endoleak (n = 2), they underwent an intervention for endoleak and did not have diameters available after their intervention (n = 3), or if they had a continued endoleak that could account for an increase in aneurysm sac diameter (n = 11). This left 27 patients with more overlapping components than the required contralateral limb/gate overlap (mean follow-up time 40.6 +/- 17.0 months) and 67 patients with required gate overlap (mean follow-up time 46.2 +/- 15.9 months). RESULTS: Subjects with increased component overlap (mean overlap 87.1 mm +/- 57.4 mm) were not protected from aneurysm sac expansion when compared to those with the minimum required gate overlap (mean overlap 31.2 mm +/- 3.4 mm). There was no association of total distance of overlap with aneurysm sac size change by diameter or volume (r(2) = 0.00034, P = .86 for diameter and r(2) = 0.0019, P = .68 for volume). Increasing percentage of overlap within the aneurysm sac was likewise not associated with aneurysm sac decrease in diameter (r(2) = 0.0028, P = .61). Few patients had large percentages of original graft overlap (mean 26.2% +/- 14.1% for the increased overlap group and 18.6% +/- 5.5% for the required overlap group, P = .0097). CONCLUSION: Partial graft overlap involving multiple original components from proximal and distal extensions is not protective against aneurysm sac expansion due to transgraft ultrafiltration. This suggests that transgraft ultrafiltration is not impeded by having partial double layers of original material. All patients who received the original Excluder and have late aneurysm sac expansion in the absence of endoleak should have as complete relining as feasible with low permeability components if sac shrinkage is the surrogate goal.

The value of 3D-CT angiographic assessment prior to carotid stenting.

OBJECTIVE: Anatomic suitability for carotid artery stenting (CAS) is determined by arteriography, but this has a discrete stroke risk. We evaluated the use of multidetector CT angiography with three-dimensional reconstruction (3D-CTA) as a noninvasive screening tool for prospective CAS patients. METHODS: Between 2003 and 2006, 90 CAS procedures were performed by vascular surgeons at our institution. At the discretion of the operating surgeon, 59 of the potential candidates for CAS underwent screening 3D-CTA of the aortic arch and carotid arteries. Results were used in patient selection and then analyzed retrospectively to determine clinical utility. RESULTS: Analysis of 3D-CTA data by the operating surgeon allowed stratification of patients into four groups: (1) appropriate for CAS via femoral approach (n = 37, 63%); (2) appropriate for CAS with transcervical access due to adverse arch anatomy (n = 2, 3%); (3) borderline anatomy for CAS (n = 5, 9%); or (4) not appropriate anatomy for CAS (n = 15, 25%). Group 1 had 100% technical success with one minor stroke. Group 2 had successful transcervical CAS without stroke. Group 3 patients underwent arteriography but CAS was aborted in four out of five cases for the same reason that had been identified by 3D-CTA (internal carotid artery [ICA] tortuosity n = 2, ICA string sign with distal disease n = 2). The one failure in group 3 was the result of a previously placed common carotid stent extending into an already unfavorable aortic arch. Group 4 patients underwent endarterectomy (n = 7) or continued medical management (n = 8) instead of CAS (without arteriography) because of the following reasons, cited alone or in combination: common carotid tandem stenosis n = 5, difficult arch anatomy n = 2, ICA tortuosity n = 2, extreme lesion calcification or length n = 4, ICA string sign or occlusion n = 3, concomitant intracranial disease n = 2, and stenosis overestimated by duplex n = 3. The overall 30-day stroke rate, on an intention to treat basis, for patients that underwent preprocedural 3D-CTA was 2.3% (one major [NIH stroke scale >3] and one minor stroke). CONCLUSIONS: In our initial experience, 3D-CTA reconstruction of the aortic arch and carotid arteries significantly influenced the plan for CAS in 37% of patients. Patients with clear anatomic contraindications to CAS can be excluded without the risks of arteriography. 3D-CTA further facilitates the CAS procedure by anticipating potential procedural. The cost-effectiveness and potential impact of this imaging modality on CAS outcomes deserve further study.

Clinical trial results of a modified gore excluder endograft: comparison with open repair and original device design.

A multicenter phase II clinical trial of aneurysm treatment was performed with the modified Gore Excluder bifurcated endoprosthesis (m-EBE, n = 193) and compared with previously reported results from the same group of the original unmodified device (EBE, n = 253) or standard open aneurysm exclusion (control, n = 99). Graft modifications were primarily related to the proximal attachment site and included an increase in the length of the external expanded polytetrafluoroethylene and modifications of the anchor configuration. Preprocedural characteristics, periprocedural clinical events, and postprocedural clinical and radiographic follow-up at 1, 6, 12, and 24 months were analyzed with univariate and multivariate statistics. Device placement was successful in all cases, and there were no aneurysm ruptures in any group. Survival to 2 years was similar in all groups. Early major adverse events with the m-EBE were similar to those with the EBE (14.5% vs. 14%, P = 0.9) and markedly reduced compared to the control group (60.6%, P < 0.0001). After 30 days, there was no significant difference in the occurrence of major adverse events between endoluminal treatment and open controls. The rates of documented endoleak and increased aneurysm size at each follow-up interval were not significantly different between the two endoluminal devices. However, there was a trend toward fewer reinterventions from 14 to 28 months with the m-EBE (2% vs. 6% with the EBE, P < 0.06). There were also significantly fewer major adverse events associated with the m-EBE compared to the EBE during 14- to 28-month follow-up (15.6% vs. 24.9%, P = 0.037), in part due to the difference in reinterventions. The safety and efficacy of the m-EBE are statistically similar to the original device, although there was a reduction in major late adverse events between the two iterations of the endograft. This difference appears to be related to increased operator experience and changing treatment algorithms. Compared with open aneurysm repair, endoluminal repair with the m-EBE offers advantages in the reduction of early major adverse events while maintaining similar survival and rupture-free outcomes in the intermediate term.

The effect of endograft relining on sac expansion after endovascular aneurysm repair with the original-permeability Gore Excluder abdominal aortic aneurysm endoprosthesis.

OBJECTIVE: Endovascular abdominal aortic aneurysm repair (EVAR) with the original-permeability Excluder (W.L. Gore & Associates, Flagstaff, Ariz) has been associated with postoperative sac expansion in the absence of endoleak. In these cases, we have performed an endovascular revision, relining the original endograft with another Excluder, in an effort to arrest sac expansion by reducing permeability. We have studied these cases to determine the effect of relining on aneurysm expansion. METHODS: Patients who demonstrated sac expansion (>or=5 mm diameter, >or=5% three-dimensional volume) after EVAR with the original Excluder were evaluated. Between 1999 and 2004, the original-permeability endoprosthesis was used in 97 patients who underwent EVAR for asymptomatic abdominal aortic aneurysm (AAA). Sac expansion occurred in 24 patients, of which multiple imaging modalities showed 12 had expansion without demonstrable endoleak. Nine of the 12 have had endovascular relining, and five of these nine have >6 months follow-up to form the primary basis for this report. RESULTS: AAA size was stable or smaller in the first 6 months after the original EVAR for all patients. Once expansion began (typically in the time frame of 6 to 12 months), multimodality imaging showed no aneurysm spontaneously decreased in size without intervention, despite the absence of endoleak (n = 12). Expansion exceeded clinically significant thresholds at 30 months (mean) by diameter criteria and 22 months (mean) by three-dimensional volume criteria for the five patients with >6 months follow-up after relining. Endovascular relining was performed at a mean of 36 months, with a mean hospital stay of 1 day, and no morbidity or mortality. Over the entire duration of expansion (mean, 26 months), aneurysms expanded by 6.0 +/- 1 mm/year diameter and by 12% +/- 2%/year by three-dimensional volume. At a mean of 16 months follow-up after relining with another Excluder, the mean diameter decrease was 2.0 mm/year (P < .03) and the mean volume decrease was 2.6%/year (P < .01). After relining, all AAAs were smaller by diameter or volume, or both, exceeding thresholds defining shrinkage in two of the five with >6 months follow-up after relining. There was no rupture, migration, endoleak, conversion to open repair, or aneurysm-related death in any patient. CONCLUSIONS: It appears from the initial follow-up that AAA expansion owing to permeability issues after EVAR with the original Excluder can be arrested by endovascular relining with a low-permeability Excluder endoprosthesis.

Elastic and rupture properties of porcine aortic tissue measured using inflation testing.

A new inflation test device was developed to study the mechanical properties of aortic tissue. The device was used to measure failure (rupture) strength and to determine the nonlinear, anisotropic elastic properties of porcine thoracic aorta. The tester was designed to stretch initially flat, circular tissue specimens to rupture under uniform biaxial loading. Water was chosen as the pressurizing fluid. Mechanical stretch and radius of curvature during inflation were measured optically in two orthogonal directions, and the Cauchy stress components were calculated from the deformation and the applied pressure. All porcine samples that ruptured successfully did so via a tear in the circumferential direction. Thus, the failure strength was taken to be the stress in the axial direction immediately prior to rupture. The mean failure strength was 1.75 MPa and mean axial stretch at failure was 1.52. These values agree well with published data for other arterial tissues. The nonlinearly elastic deformation behavior was modeled using a hyperelastic constitutive law of the type proposed by Holzapfel et al. [Holzapfel GA, Gasser TC, Ogden RW. J Elasticity 2000;61:1-48]. The results showed that the dominant directions of anisotropy in the porcine aortas were approximately 45 degrees to the axial and circumferential directions, and that the isotropic contribution to the constitutive model was insignificant.