Nikolaos Melas

Anaconda Aortic Stent-Graft: Single-Center Experience of a New Commercially Available Device for Abdominal Aortic Aneurysms

Purpose: To report a retrospective evaluation of the efficacy and midterm clinical results of the Anaconda stent-graft in the endovascular repair of infrarenal abdominal aortic aneurysms. Methods: Fifty-one patients (48 men; mean age 71±8 years, range 62–89) were treated with the Anaconda stent-graft from January 2006 to September 2007. Six patients were considered at high risk for open repair (defined as ASA grade 3) and 10 had undergone previous laparotomy. The mean neck diameter and length were 26 mm (range 22–30) and 18.5 mm (range 14–35), respectively. Mean proximal neck angulation was 30° (range 5–60). Severe iliac artery tortuosity (>60°) was seen in 20 (39%) patients; 3 (6%) had a proximal aneurysm neck angle >45°. Results: The technical success rate was 100%; intraprocedurally, 7 (14%) stent-grafts were repositioned to address renal artery occlusion by the graft (n=1) or type I endoleak. This maneuver resolved 6 of the 7 situations; a remaining endoleak required a proximal cuff to seal it. The procedural success rate (no major complication at 30 days) was 94%. The mean follow-up was 16 months (range 1–21). Five (10%) endoleaks (1 type I, 4 type II) and 1 (2%) graft migration occurred. The overall reintervention rate was 6%. Two (4%) patients died in late follow-up. Conclusion: The Anaconda stent-graft appears both safe and effective in terms of midterm clinical outcome and compares favorably with previously reported EVAR results. The ability to reposition the stent-graft is a particular advantage.

Aortic and Iliac Fixation of Seven Endografts for Abdominal-aortic Aneurysm Repair in an Experimental Model Using Human Cadaveric Aortas

OBJECTIVE To evaluate the proximal and distal (iliac) fixation of seven self-expanding endografts, used in the endovascular treatment (EVAR) of abdominal-aortic aneurysm (AAA), by measuring the displacement force (DF) necessary to dislocate the devices from their fixation sites. METHODS A total of 20 human cadaveric aortas were exposed, left in situ and transected to serve as fixation zones. The Anaconda, EndoFit aorto-uni-iliac, Endurant, Powerlink, Excluder, Talent and Zenith stent grafts were deployed and caudal force was applied at the flow divider, through a force gauge. The DF needed to dislocate each device ≥ 20 mm from the infrarenal neck was recorded before and after moulding-balloon dilatation. Cephalad force was similarly applied to each iliac limb to assess distal fixation before and after moulding-balloon dilatation. RESULTS Endografts with fixation hooks or barbs displayed a significantly higher DF necessary to dislocate the proximal portion compared with devices with no such fixation modalities (p < 0.001). Balloon dilatation produced a significant increase in DF in both devices with (p < 0.001) or without (p = 0.003) hooks or barbs. Suprarenal support did not enhance proximal fixation (p = 0.90). Balloon dilatation significantly increased the DF necessary to dislodge the iliac limbs (p = 0.007). CONCLUSIONS Devices with fixation hooks displayed higher proximal fixation. Moulding-balloon dilatation increased proximal and distal fixation. Suprarenal support did not affect proximal fixation.

Aortoduodenal Fistulas after Endovascular Stent-Graft Repair of Abdominal Aortic Aneurysms: Single-Center Experience and Review of the Literature

Purpose: To report a single-center experience with aortoduodenal fistula (ADF) after successful endovascular aneurysm repair (EVAR) of an infrarenal abdominal aortic aneurysm (AAA). Methods: Five patients (all men; mean age 68.4 years, range 60–75) developed an ADF between 18 days to 1 year after successful EVAR using 3 types of commercially available endografts: 1 bifurcated Anaconda, 1 unibody Powerlink, and 3 EndoFit stent-grafts in a tubular (n=1) or aortomonoiliac configuration (n=2). The internal iliac artery was not occluded in any of the cases. Results: Hematemesis and diffuse abdominal pain constituted the main symptoms leading to the diagnosis of ADF, which was confirmed on computed tomography. Infection was the etiology of the ADF in 3 patients; all underwent emergency surgical exploration, but 1 died in hospital; the other 2 have survived from 1 to 3 years after an emergency procedure. The other 2 ADFs developed in patients with large type I endoleaks; 1 patient died before surgery could be performed and the other one 18 hours after laparotomy. All stent-grafts were removed; none displayed any defects. Conclusion: ADF is a rare but dangerous complication of EVAR. The sequela may be primarily attributed to graft infection, as seen in this series. However, the exact pathogenesis of the pathology remains largely unknown. Prompt diagnosis and intervention are crucial to avoid a fatal outcome.

Comparison of the impact of open and endovascular abdominal aortic aneurysm repair on renal function

OBJECTIVE The impact of any intervention on renal function is a crucial determinant of outcome. Open (OR) and endovascular (EVAR) abdominal aortic aneurysm (AAA) repair can affect renal function during the short and longer term. This study aimed to directly compare the effect of those different types of aneurysm repair during a period of 2 years. METHODS This was a nested case-control study including patients undergoing either OR or EVAR of an infrarenal AAA. Three groups were included: OR, EVAR with suprarenal endograft fixation, and EVAR with infrarenal fixation. These were matched for age (within 2 years), sex, AAA size (within 1 cm), hypertension, smoking, and proximal neck diameter (within 5 mm). The primary end point was change in estimated glomerular filtration rate (eGFR) calculated by the Chronic Kidney Disease Epidemiology Collaboration formula at baseline, 6 months, 12 months, and 2 years. RESULTS A total of 225 patients were included [(45 ORs matched vs 90 suprarenal and 90 infrarenal fixation EVARs; 35 women (16%); age, 71 ± 8 years; AAA size, 6.4 ± 1 cm]. Groups did not differ significantly in terms of diabetes, hypercholesterolemia, or baseline eGFR (P = .89). On average, those undergoing OR lost a mean 5.39 mL/min/1.73 m(2) (P = .48) within 1 year and 5.49 units (P = .42) after 2 years. The suprarenal fixation patients lost 5.58 units (P = .002) after 1 year and 6.57 units (P = .001) after 2 years. Finally, the infrarenal fixation patients lost 0.53 unit (P = .74) after 1 year and 2.24 units (P = .22) after 2 years. CONCLUSIONS OR and suprarenal fixation EVAR are associated with significant declines in renal function during 2 years, in contrast to infrarenal EVAR fixation. The patterns of eGFR decline in OR and suprarenal fixation EVAR are not similar, suggesting different causal mechanisms.

Helical EndoStaples enhance endograft fixation in an experimental model using human cadaveric aortas

OBJECTIVE This study evaluated the contribution of Aptus EndoStaples (Aptus Endosystems, Sunnyvale, Calif) in the proximal fixation of eight endografts used in the endovascular repair of abdominal aortic aneurysms (EVAR). METHODS Nine human cadaveric aortas were exposed, left in situ, and transected to serve as fixation zones. The Zenith (Cook, Bloomington, Ind), Anaconda (Vascutek, Inchinnan, Scotland, UK), Endurant (Medtronic, Minneapolis, Minn), Excluder (W. L. Gore and Associates, Flagstaff, Ariz), Aptus (Aptus Endosystems), Aorfix (Lombard Medical, Didcot, UK), Talent (Medtronic), and AneuRx (Medtronic) stent grafts were proximally deployed and caudal displacement force (DF) was applied via a force gauge, recording the DF required to dislocate each device ≥20 mm from the infrarenal neck. Measurements were repeated after four and six EndoStaples were applied at the proximal fixation zone, as well as after a Dacron graft was sutured at the proximal neck in standard fashion. Finally, a silicone tube was used as a control fixation zone to test the DF of grafts with EndoStaples in a material that exceeded the integrity of a typical human cadaveric aorta and provided a consistent substrate to examine the differential effect of variable degrees of EndoStaple implantation using zero, two, four, and six EndoStaples. RESULTS In the cadaveric model, the mean DF required to dislocate the endografts without the application of EndoStaples was 19.73 ± 12.52 N; this increased to 49.72 ± 12.53 N (P < .0001) when four EndoStaples where applied and to 79.77 ± 28.04 N when six EndoStaples were applied (P = .003). The DF necessary to separate the conventionally hand-sutured Dacron graft from the aorta was 56 N. In the silicone tube model, the Aptus endograft without EndoStaples withstood 3.2 N of DF. The DF increased to 39 ± 3 N when two EndoStaples were added, to 71 ± 6 N when four were added, and to 98 ± 5 N when six were added. In eight of the 13 cadaver experiments conducted with four and six EndoStaples, the displacement occurred as a result of complete aortic transection proximal to the fixation site, indicating that aortic tissue integrity was the limiting factor in these experiments. CONCLUSIONS The fixation of eight different endografts was increased by a mean of 30 N with four Aptus EndoStaples and by a mean of 57 N with six EndoStaples in this model. Endostaples can increase endograft fixation to levels equivalent or superior to that of a hand-sewn anastomosis. The application of six EndoStaples results in aortic tissue failure above the fixation zone, demonstrating fixation strength that exceeds inherent aortic integrity in these cadavers.

Suprarenal graft fixation in endovascular abdominal aortic aneurysm repair is associated with a decrease in renal function

INTRODUCTION Suprarenal endograft fixation is routinely used in the endovascular repair of abdominal aortic aneurysms (EVAR) to enhance proximal endograft attachment but can be associated with an adverse outcome in renal function. This prospective study assessed the effect of suprarenal fixation on serum creatinine concentration and estimated glomerular filtration rate (eGFR), calculated by the Modified Diet in Renal Disease equation, 12 months after elective EVAR. METHODS Patients undergoing elective EVAR were divided into suprarenal vs infrarenal fixation groups matched for age, sex, smoking, and aneurysm diameter. Serum creatinine and eGFR were measured at baseline, 6, and 12 months. RESULTS Included were 92 patients (two women) with a mean age of 71 ± 7 years, with 46 in each group. No device-related complications were noted. Serum creatinine did not differ significantly between groups at 6 (P = .24) or 12 (P = .08) months but significantly increased in the suprarenal group at 12 months (1.08 ± 0.36 to 1.16 ± 0.36 mg/dL; P < .001) vs baseline. The eGFR (mL/min/1.73 m(2)) did not differ significantly at baseline between the suprarenal (85 ± 27) and infrarenal (80 ± 28; P = .33) groups or at 6 months (88 ± 29 vs 77 ± 24, respectively; P = .07). At 12 months, the suprarenal group had a lower eGFR (73 ± 23) than the infrarenal group (84 ± 26; P = .027). The eGFR at 12 months showed a significant decrease in the suprarenal (80 ± 28 to 73 ± 23; P < .001) but not in the infrarenal group (85 ± 27 to 84 ± 26; P = .48). The drop in eGFR differed significantly at 12 months in the infrarenal vs the suprarenal (0.82 vs -6.94; P < .001) group. No patient progressed to end-stage renal disease or disclosed a drop in eGFR > 30%. CONCLUSIONS In contrast to previous studies, this study suggests that suprarenal endograft fixation in elective EVAR is associated with a drop in eGFR at 12 months.

Primary EndoAnchoring in the Endovascular Repair of Abdominal Aortic Aneurysms With an Unfavorable Neck

Purpose To investigate the feasibility and early results of endoanchoring (endostapling) using a new commercially available device as an adjunctive procedure during endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs) with an unfavorable proximal neck. Methods Between June 2010 and May 2012, 13 consecutive patients (all men; median age 73 years, range 62–82) were prospectively enrolled in a 2-center registry to follow outcomes of adjunctive primary endoanchoring (Aptus HeliFX Aortic Securement System) of the proximal endograft to enhance proximal graft fixation and sealing during EVAR. Indications for proximal neck endoanchoring included at least one of the following: neck angulation 45° to 90°, length 8 to 15 mm, diameter 29 to 33 mm, conical neck configuration, or an irregularly shaped neck. The median AAA diameter was 56 mm (range 50–98). The Endurant stent-graft was implanted in 4 patients and the Zenith device in 9. Results A median of 4 endoanchors were implanted per patient (range 3–10) in adjunctive procedures that required a median 12 minutes (range 7–20). Intraoperatively, 2 proximal type I endoleaks were present following endoanchor implantation (85% primary technical success); a cuff was deployed in 1 case, which successfully sealed the endoleak (92% assisted primary technical success). The second proximal type I endoleak was minute and sealed spontaneously within 30 days. No further major device-related complications occurred intraoperatively. In the 30-day perioperative period, the only procedure-related complications were 2 type II endoleaks, which required no intervention. Over a median follow-up of 7 months (range 2–17), no further complications occurred apart from an asymptomatic internal iliac artery occlusion and a non-lethal myocardial infarction at 9 months. The type II endoleaks spontaneously sealed. No endograft migration was noticed nor loss of endoanchor integrity. No deaths occurred throughout follow-up. Conclusion Primary endoanchoring using the HeliFX aortic securement system is feasible, and early results were promising in this series.

Impaired renal function is associated with mortality and morbidity after endovascular abdominal aortic aneurysm repair

BACKGROUND Renal function may be associated with poor outcome following endovascular abdominal aortic aneurysm repair (EVAR), but this relationship has not been adequately investigated. The aim of this study is to evaluate the association of estimated glomerular filtration rate (eGFR) with cardiovascular events and all-cause mortality after EVAR. METHODS Prospective cohort study of patients undergoing elective EVAR; eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula, and patients were divided in four groups (eGFR ≥ 90 mL/min/1.73 m(2), group 1; 60-89, group 2; 30-59, group 3; <30, group 4). Composite end point consisted of death, nonfatal myocardial infarction, stroke, and vascular complications. Kaplan-Meier curves were constructed, and between-group comparisons were performed adjusted for variables that differed at baseline. RESULTS A total of 383 patients (mean age, 69 ± 8 years; mean abdominal aortic aneurysm diameter, 6.2 ± 1.4 cm) were included. Over a mean follow-up of 34 ± 12 months, the following events occurred: 20 deaths (5.2%), 15 nonfatal myocardial infarctions (3.9%), 9 nonfatal strokes (2.3%), and 7 peripheral vascular complications (1.8%). Patients with an eGFR <30 had the highest mortality (35%) and incidence of complications (80%) as per the end point (P = .009 and P < .001, respectively). Adjusted Cox-regression analysis showed that a higher eGFR at baseline by 1 mL/min/1.73 m(2) was associated with a 5% lower likelihood of complications as per the end point (P < .001; hazard ratio, 0.95; 95% confidence interval, 0.94-0.97) and a 6% lower likelihood of death (P < .001; hazard ratio, 0.94; 95% confidence interval, 0.92-0.97). CONCLUSIONS Impaired renal function is associated with an increase in cardiovascular events and mortality following elective EVAR.

Reporting mid- and long-term results of endovascular grafting for abdominal aortic aneurysms using the aortomonoiliac configuration

PURPOSE This study evaluated the feasibility, efficacy, and durability of a specific aortomonoiliac endograft for the treatment of abdominal aortic aneurysm (AAA) during a midterm follow-up. METHODS From January 2002 until November 2008, 106 patients (6 women; mean age, 73.37 +/- 7.39 years) were treated for an AAA using an EndoFit aortomonoiliac graft (LeMaitre Vascular, Burlington, Mass). All procedures were elective. RESULTS Mean follow-up was 34.9 months (SD, 20.08; range, 2-81 months). Long-term data (follow-up >60 months) were available for nine patients, none of which reported any vascular or procedure related complications. Three of the 106 patients (2.83%) died during early follow-up (<30 days); eight died during late follow-up (7.54%). Endograft infection developed in two patients (1.88%), and an aortoduodenal fistula developed in two (1.88%). Also observed were 15 type II (14.15%) and three type I (2.83%) endoleaks. Femorofemoral bypass thrombosis was detected in two patients (1.88%). CONCLUSION In this retrospective analysis, the aortomonoiliac configuration for elective AAA repair was proven to be safe and efficacious. Midterm and long-term follow-up results in this series compare well with previously reported results for AAA endografting using both bifurcated and aortomonoiliac endoprostheses.

Abdominal aortic aneurysm: a review of the genetic basis.

Background: Abdominal aortic aneurysm (AAA) is a complex disease with a largely unknown pathophysiological background and a strong genetic component. Various studies have tried to link specific genetic variants with AAA. Methods: Systematic review of the literature (1947-2009). Results: A total of 249 studies were identified, 89 of which were eventually deemed relevant to this review. Genetic variants (polymorphisms) in a wide variety of genes, most of which encode proteolytic enzymes and inflammatory molecules, have been associated with AAA development and progression. Conclusion: The genetic basis of AAA remains unknown, and most results from ‘‘candidate-gene’’ association studies are contradictory. Further analyses in appropriately powered studies in large, phenotypically well-characterized populations, including genome-wide association studies, are necessary to elucidate the exact genetic contribution to the pathophysiology of AAA.