Gregory A. Stanley

Volumetric analysis of type B aortic dissections treated with thoracic endovascular aortic repair

BACKGROUND Type B aortic dissections are being successfully treated by thoracic endovascular aortic repair (TEVAR). Postoperative false lumen patency has been associated with aneurysmal dilatation and rupture of the thoracic aorta, necessitating further intervention. This is the first volumetric analysis of type B aortic dissections comparing patients with and without false lumen thrombosis (FLT) after TEVAR. We hypothesized that a greater increase in postoperative true lumen volume will lead to FLT, and without this change, false lumen patency will result. METHODS Preoperative and postoperative computed tomography angiography (CTA) imaging was analyzed using three-dimensional reconstruction to measure the short- and long-axis diameter and cross-sectional area of the true lumen, false lumen, and total aorta. Measurements were taken at 5-cm intervals from the left subclavian artery to the aortic bifurcation. Pre- and postoperative volumetric data were calculated and compared in patients with and without postoperative FLT. RESULTS Between 2006 and 2010, 132 patients underwent thoracic aortic stent grafting. Of these, 31 (23%) had thoracic endografting for type B aortic dissection. Pre- and postoperative CTA images were available for analysis in 23 patients with a mean age of 59 ± 14 years treated for acute, complicated (n = 8, 35%), and chronic (n = 15, 65%) indications. Mean follow-up imaging was 9 months (range, 1-39 months). Thirteen patients (56%) had postoperative FLT and 10 (43%) had persistent false lumen patency. The dissections involved the left subclavian artery (n = 12), visceral arteries (n = 14), renal arteries (n = 16), and iliac arteries (n = 15). The left subclavian artery was intentionally covered in 15 patients (65%). There were no significant differences in age, acute vs chronic dissection, branch vessel involvement, coverage of the left subclavian artery, or distal extent of the endograft between patients with and without postoperative FLT. Patients with postoperative FLT had a significantly smaller preoperative maximum thoracic aortic diameter (5.05 ± 1.0 vs 6.30 ± 1.4 cm; P = .02). Volumetric analysis demonstrated significantly smaller preoperative true lumen volume (141.3 ± 68 vs 230.5 ± 92 cm(3); P = .01) in patients with FLT, but no difference in preoperative false lumen volume. Patients with FLT had a significant increase in the volume percentage of the true lumen from 42.7% to 61.7% (P = .02) after stent graft repair, compared with an increase from 46.7% to 47.7% (P = .75) in patients with persistent false lumen patency. CONCLUSIONS This volumetric study of type B aortic dissection treated with TEVAR suggests that the ability of the endograft to significantly increase the true lumen volume as a percent of the total aorta most accurately predicts postoperative FLT. This is best demonstrated in a nonaneurysmal dissection regardless of timing since dissection.

Hybrid Endovascular Treatment of an Anomalous Right Subclavian Artery Dissection in a Patient With Marfan Syndrome

We report the case of a 26-year-old female patient with Marfan syndrome and an aberrant right subclavian artery (ARSA) with associated Kommerell diverticulum. The patient presented with spontaneous acute dissection of the ARSA that showed fusiform dilation to 4 cm in diameter. Definitive treatment was performed using a two-stage hybrid endovascular technique, including extrathoracic bilateral upper extremity bypass and thoracic endovascular aortic repair with debranching of the right and left subclavian arteries. This was followed by coil and plug embolization to exclude the dissection and prevent subsequent endoleak.

Effect of Ethnicity and Insurance Type on the Outcome of Open Thoracic Aortic Aneurysm Repair

OBJECTIVES Mortality and complication rates for open thoracic aortic aneurysm repair have declined but remain high. The purpose of this study is to determine the influence of ethnicity and insurance type on procedure selection and outcome after open thoracic aneurysm repair. METHODS Using the Nationwide Inpatient Sample database, ethnicity and insurance type were evaluated against the outcome variables of mortality and major complications associated with open thoracic aneurysm repair. The potential cofounders of age, gender, urgency of operation, and Deyo index of comorbidities were controlled. RESULTS Between 2001 and 2005, a total of 10,557 patients were identified who underwent elective open thoracic aneurysm repair, with a significantly greater proportion of white patients (n = 8524) compared with black patients (n = 819), Hispanic patients (n = 556), and patients categorized as other (n = 658). Most patients (67%) were male. Almost half (45%) of the procedures were performed for urgent/emergent indications. Overall mortality was 10.7% (n = 1126) and the rate of spinal cord ischemia was 0.4% (n = 43). Univariate analysis revealed significant differences among race with regard to surgery type, income, hospital region, hospital bed size, and insurance type (P < 0.0001). Differences between insurance coverage were significant for gender, surgery type, income, hospital region, and race (P < 0.0001). Bivariate analysis by race revealed differences for death (P < 0.0001), pneumonia (P < 0.0001), renal complications (P = 0.011), implant complications (P < 0.0001), temporary tracheostomy (P = 0.004), transfusion (P < 0.0001), and intubation (P < 0.0001). In terms of payer status, bivariate analysis by insurance coverage revealed differences in death (P < 0.0001), central nervous system complications (P = 0.008), pneumonia (P < 0.0001), myocardial infarction (P = 0.001), infection (P < 0.0001), renal complications (P < 0.0001), malnutrition (P < 0.0001), temporary tracheostomy (P < 0.0001), spinal cord ischemia (P = 0.001), transfusion (P < 0.0001), and intubation (P < 0.0001). CONCLUSIONS A high percentage of open thoracic procedures (45%) are performed urgently or emergently in the United States, which is associated with increased morbidity and mortality. Both ethnicity and payer status were associated with significant differences in surgical outcomes, including mortality and frequency of complications after open thoracic aortic aneurysm repair.

Endurant continues to impress, but long-term data are still needed for success.

In the past 2 decades since the first endovascular aneurysm repair (EVAR) was performed, transformational progress in device design, components, and delivery systems has ushered in a state of sophisticated surgical care for the treatment of infrarenal abdominal aortic aneurysms (AAAs). The major limitation to successful EVAR continues to be the aneurysm neck anatomy, which determines the ability of the endograft to form an adequate seal with the aortic wall at the proximal landing zone. Poor apposition of the proximal stent-graft can lead to the development of type I endoleaks and predict higher reintervention rates, aneurysm sac enlargement, and increased long-term mortality. While variability exists in the definition of hostile neck characteristics, most experts would agree that neck length ,15 mm, diameter .28 mm, infrarenal angulation .60u, .50% circumferential thrombus or calcification, and .2-mm reverse taper represent significantly challenging anatomy. In fact, these characteristics generally fall outside of the instructions for use (IFU) for most currently manufactured devices. Additionally, iliac artery size (,8 or .25 mm), severe tortuosity or calcification, and a distal landing zone ,15 mm may limit device delivery and result in iliac artery rupture, dissection, limb kinking, or occlusion, as well as type Ib endoleaks. Despite these relative contraindications, many physicians continue to implant devices outside of the manufacturer’s IFU. While often successful in avoiding the untoward morbidity and mortality of open repair, device implantation outside of the designated IFU is associated with increased complications, including endoleaks and need for secondary interventions, typically in longer term followup of between 2 and 3 years. Fortunately, advances in device design have specifically addressed these anatomical confines and are now expanding the suitability of EVAR to patients with challenging aneurysm neck and iliac artery anatomy. The Endurant Stent Graft System is the latest iteration of the Medtronic (Santa Rosa, CA, USA) infrarenal aortic stent-graft and was approved for use in the United States in December 2010. This graft has been specifically designed with the intent of broadening the endograft’s IFU to accommodate more challenging anatomy, including a 10-mm neck length. In this issue of JEVT, Kvinlaug et al. report the 6-month follow-up after treating 111 elective infrarenal AAAs at 3 Canadian vascular surgery centers using the Endurant Stent Graft System. One third of the patients in this study were deemed to have challenging aortoiliac anatomy by preoperative imaging using the definitions above, although challenging iliac artery anatomy was simply defined as diameter ,7 mm. The authors presented an overall procedure-related mortality of 0.9% and a periprocedural complication rate of 17.1%, on par with other recently published series. No technical failures were encountered; however, 9 (8.1%) patients had intraoperative complications, leading to 8

In Vitro Analysis of Type II Endoleaks and Aneurysm Sac Pressurization on Longitudinal Stent-Graft Displacement

Purpose To evaluate the effects of type II endoleaks and sac pressurization on stent-graft displacement following endovascular aneurysm repair (EVAR). Methods Experimental silicone infrarenal aneurysm (6-cm) models were “treated” with a Talent stent-graft deployed with 20-mm proximal and distal landing zones. Inflow and outflow vessels were created as part of the silicone model to control flow into the aneurysm sac. All aneurysm models were uniform, with a diameter neck of 31 mm, a neck length of 20 mm, and iliac artery diameters of 16 mm. The aortic model was secured in a water bath to a pulsatile pump under physiological conditions; the output phase ratio (%systole/%diastole) was set at 65/35 with a pump rate of 80 beats per minute. Commercially available bifurcated stent-grafts were then displaced in vitro utilizing a linear motion apparatus attached to a force gauge. The mean arterial pressure (MAP) and pulse pressure (PP) at the aortic inflow were 60.1±3.1 and 38.3±7.8 mmHg, respectively. Peak force to cause initial stent-graft migration with and without a type II endoleak was recorded and compared. Results In aneurysm sacs with no endoleak, the MAP and sac PP were 32±6.4 and 6±1.3 mmHg, respectively (p<0.01). In aneurysm sacs with a type II endoleak, the MAP and sac PP were 54.1±9.7 and 16.1±4.1 mmHg, respectively (p<0.02). Peak force to initiate migration was 16.0±1.41 N (range 15–18) with no endoleak vs. 23.2±2.2 N (range 20–25) in those with a type IIa endoleak and 23.5±2.5 N (range 20–26) in those with a type IIb endoleak (p<0.001). Conclusions Type II endoleaks are associated with a significantly increased sac pressure. Increased sac pressurization from type II endoleaks results in a significantly greater force to displace a stent-graft longitudinally. Type II endoleaks may therefore inhibit migration and offer a benefit following EVAR; however, clinical correlation of these results is required.

Commentary: Midterm Endurant results place more confidence in off-label use for EVAR.

It is no secret that many aortic stent-grafts are implanted in patients with anatomical criteria outside of the manufacturer’s instructions for use (IFU). This ‘‘off-label’’ application of endografts in the treatment of infrarenal abdominal aortic aneurysms, particularly those with hostile neck anatomy, has often been unkindly critiqued for the increased rate of late type I endoleak and aneurysm-related mortality. Much of this criticism is in response to bad experiences and unexpected late graft failures with early-generation devices that were plagued by well-known shortcomings, including inadequate proximal seal, type I endoleak, graft migration, stent fracture, and limb thrombosis. The ‘‘next-generation’’ devices, including Medtronic’s Endurant stent-graft, incorporate significant technological advancements in endograft design that expand the applicability of standard endovascular aneurysm repair (EVAR). Perhaps the most telling sign of the Endurant’s positive reception was the willingness of many endovascular specialists to move beyond the IFU indications, thereby pushing the treatment envelope toward shorter proximal neck lengths, severe infrarenal angulation, and significant iliac tortuosity. Numerous reports of early Endurant outcomes were favorable for both onand offlabel indications, though an increased incidence of type I endoleak was observed in offlabel anatomy. Until now, longer-term data have been lacking, leaving doubts about durability and efficacy in longer follow-up. In this issue of the JEVT, Troisi et al. provide us with midterm performance data of the Endurant stent-graft in both onand offlabel anatomical circumstances. The authors findings demonstrated a small but persistently elevated risk of type I endoleak in the offlabel patient cohort (freedom from type I endoleak 96.2% estimated to 5 years); however, this did not translate into a significant difference in survival between the onand offlabel groups. Notably, no new type I endoleaks were identified in the off-label patients beyond the initial reporting period of 1 year, which meant that in those patients with hostile neck anatomy, the Endurant graft maintained an intact proximal seal. I wish to offer a few words of recognition to the authors for their effort to submit this highly anticipated and necessary follow-up data. As the limits of the proximal landing zone continue to be pushed, these data add at least another layer of reassurance (and esteem) that the technological advances applied to the Endurant stent-graft have indeed produced a capable and durable device. While doubts may remain in the minds of the readership, certainly this report offers a compelling argument for the judicious use of

The sequential catheterization amid progressive endograft deployment technique for fenestrated endovascular aortic aneurysm repair

&NA; Fenestrated endovascular aneurysm repair (FEVAR) is an alternative to open repair of complex aortic aneurysms. Despite promising short‐term results, the technical complexities of this procedure remain a considerable challenge. The risk of technical failure with loss of visceral or renal arteries is ubiquitous even in the most experienced hands, and thus many patients with unfavorable anatomy are frequently denied FEVAR. We have adopted a new technique for FEVAR that involves retrograde brachial artery access and stepwise deployment of the endograft during target vessel catheterization, overcoming many anatomic limitations encountered from a transfemoral approach. This technique, termed sequential catheterization amid progressive endograft deployment, has become our preferred approach for FEVAR and is described in this article. Of note, currently available Food and Drug Administration‐approved fenestrated endografts may not be amenable to sequential catheterization amid progressive endograft deployment as this technique requires preloaded wires incorporated into the endografts.

Advanced Techniques for Treating Juxtarenal and Pararenal Abdominal Aortic Aneurysms: Chimneys, Periscopes, Sandwiches and Other Methods

The complex aortic anatomy of patients who present with juxtarenal and pararenal abdominal aortic aneurysms requires advanced techniques to ensure adequate coverage and complete exclusion of the aneurysm. Parallel stent grafting is one option for endovascular repair of complex aneurysms. Using chimneys, periscopes, or snorkels, it is possible to extend the length of the proximal seal zone and maintain perfusion to branch vessels. Because readily available stent grafts and covered stents are used, this technique is highly adaptable to each patients unique anatomical challenges. However, the complexity of these procedures requires careful preoperative planning, excellent intraoperative imaging capabilities, a thorough understanding of technique, and anticipation of potential procedural pitfalls and complications. We present our experience with chimney/snorkel and sandwich techniques as a reliable and effective treatment strategy for complex aortic aneurysm repair.