The Influence of Different Types of Stent Grafts on Aneurysm Neck Dynamics after Endovascular Aneurysm Repair
ABSTRACT Dynamic imaging provides insight into aortic shape changes throughout the cardiac cycle. These changes may be important for proximal aortic stent graft fixation, sealing and durability. The objective of this study is to analyse the influence of different types of stent grafts on dynamic changes of the aneurysm neck.
Pre- and postoperative electrocardiography (ECG)-gated computed tomographic angiography (CTA) scans were obtained in 30 abdominal aortic aneurysm (AAA) patients, 10 each from three different types of stent grafts (10 Talent, Endurant, and Excluder). Each dynamic CTA dataset consisted of eight reconstructed images over the cardiac cycle. Aortic area and radius changes during the cardiac cycle were determined at two levels: (A) 3 cm above and (B) 1 cm below the lowermost renal artery. Radius changes were measured over 360 axes, and plotted in a polar plot. An ellipse was fitted over the plots to determine radius changes over the major and minor axis for assessment of the asymmetric aspect and most prominent direction of distension.
Baseline characteristics did not differ significantly between the three groups. Preoperatively, the aortic area increased significantly (p < 0.001) over the cardiac cycle in all patients at both levels: (A) mean increase 8.3 +/- 4.1% (2.0-17.3%); (B) mean increase 5.9 +/- 4.2% (1.9-12.4%). The postoperative aortic area increase over the cardiac cycle did not differ significantly from preoperative increases: (A) mean increase 9.9 +/- 2.2% (4.4-20.0%); (B) mean increase 7.7 +/- 2.4% (3.8-12.4%). The difference between radius change over the major and minor axis was significant both pre- and postoperatively for all three stent grafts, indicating asymmetric distension. Suprarenal, the distension showed a tendency to right-anterior and infrarenal to left-anterior. The distension and direction of the aortic expansion was preserved after stent grafting. There were no differences between the three types of stent grafts regarding their impact on the aortic distension or direction of this distension.
The aorta expands significantly and asymmetrically throughout the cardiac cycle. After implantation of abdominal aortic stent grafts, the aortic distension and direction of distension remain equally preserved in all three groups. The three stent graft types studied seem to be able to adapt to the asymmetric dynamic aortic shape changes.
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ABSTRACT: The proximal abdominal aortic aneurysm (AAA) neck expands significantly during the cardiac cycle, both before and after endovascular aneurysm repair (EVAR). Clinical consequences of this pulsatility were anticipated but have never been reported. This study investigated whether there is a relation between stent graft migration and preoperatively measured pulsatility of the proximal aneurysm neck. EVAR patients with a preoperative dynamic computed tomography angiography (CTA), an immediate postoperative, and a CTA at 3 years after EVAR were included. The preoperative dynamic CTAs consisted of eight images per heartbeat. Aortic diameter and area changes per heartbeat were measured at two levels: (A) 3 cm above and (B) 1 cm below the most distal renal artery. Postoperatively, the distance between the most distal renal artery and the most proximal stent graft ring was measured. Two patient groups were distinguished according to whether migration during follow-up occurred (group 1) or had not occurred (group 2). The aneurysm neck dynamics of the two groups were compared by using the t-test for unpaired data and multivariable logistic regression analyses were performed. Mean values are presented with the standard deviation. Included were 26 patients (19 Talent, 6 Excluder and 1 Lifepath). Stent graft migration of > or =5 mm occurred in 11 patients (group 1). The pulsatility of the AAA neck in these patients was compared with the pulsatility in 15 patients with no graft migration (group 2). There were no significant differences in aortic neck characteristics (angulation, length and diameter) or degree of stent graft oversizing between the two groups. At level A in group 1 versus group 2, the diameter increase during the cardiac cycle was 2.0 +/- 0.3 versus 1.7 +/- 0.3 mm and the aortic area increase was 49 +/- 15 versus 33 +/- 12 mm(2). At level B in group 1 versus group 2, the diameter increase per heartbeat was 1.8 +/- 0.3 versus 1.6 +/- 0.4 mm, and the area increase was 37 +/- 10 versus 25 +/- 15 mm(2). The heartbeat-dependent diameter and area changes at both levels were significantly higher in group 1 compared with group 2. Multivariate regression analysis showed suprarenal aortic pulsatility was a significant predictor for stent graft migration after 3 years. The preoperative heartbeat-dependent aneurysm neck distension is significantly associated with stent graft migration after 3 years. The aortic pulsatility in patients with stent graft migration is significantly higher than the pulsatility in patients without stent graft migration.European journal of vascular and endovascular surgery: the official journal of the European Society for Vascular Surgery 09/2010; 40(3):326-31. DOI:10.1016/j.ejvs.2010.05.009 · 3.07 Impact Factor
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ABSTRACT: Previous studies have shown the importance of proximal and distal endograft fixation. There is little information on the middle, unsupported section of endograft within the aneurysm sac. We quantified sideways movement of the endograft within the aneurysm sac and correlated it to late adverse events. Patients who underwent endovascular abdominal aortic aneurysm (AAA) repair with a suprarenal or infrarenal endograft between January 1997 and December 2007 were analyzed for sideways endograft movement. Patients were included if they had a digital preoperative computed tomography angiogram (CTA), a postoperative CTA within 3 months after the index procedure, and at least one follow-up CTA thereafter with a minimal time interval of 6 months. The endograft position within the aneurysm sac was quantitated on cross-sectional images using a fixed vertebral body reference point. Patients with change in endograft position ≥5 mm were placed in the sideways displacement (SD) group and compared with patients with no displacement (ND; <5 mm change in position). The relationship between sideways endograft movement and endovascular aneurysm repair (EVAR)-related complications were noted for AAA rupture, AAA-related death, conversion, secondary procedures, AAA growth (≥5 mm), proximal migration (≥10 mm), and new onset of type I or III endoleaks. The study included 144 patients (mean age, 76 ± 7.6 years). Mean follow-up time was 43 ± 27 months. Fifty patients (35%) had sideways endograft movement ≥5 mm during follow-up. Baseline AAA diameter was larger (SD 60 ± 9 mm vs ND 57 ± 9 mm; P < .05) and proximal and iliac endograft fixation lengths were shorter (SD 18 ± 8 mm vs ND 24 ± 11 mm; P < .05 and SD 35 ± 14 vs ND 42 ± 16 mm; P < .05) in patients with sideways endograft displacement. There was no significant difference between the groups in AAA rupture and AAA-related death (one fatal AAA rupture, ND group). SD patients had a higher surgical conversion rate (10% vs 0%; P = .002), more secondary procedures (44% vs 6%; P < .001), more AAA sac enlargement (42% vs 10%; P < .001), more endograft migration (66% vs 5%; P < .001), and more type I or III endoleaks (36% vs 3%; P < .001). Positional stability of the endograft within the aneurysm sac is critical for the long-term success of EVAR. Sideways movement of the endograft within the aneurysm sac is associated with an increased risk of late adverse events.Journal of vascular surgery: official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter 12/2011; 55(4):947-55. DOI:10.1016/j.jvs.2011.10.093 · 2.98 Impact Factor
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ABSTRACT: To report the early results of a multicenter registry of endovascular aneurysm repair (EVAR) using the Endurant stent-graft. Patients having elective treatment of infrarenal abdominal aortic aneurysm (AAA) with the Endurant stent-graft at 3 Canadian centers were enrolled in a prospective registry between September 2008 and January 2010. In the 16-month period, 111 patients (90 men; mean age 75 years, range 53-93) were registered. Thirty-seven (33.3%) patients had challenging anatomy: short proximal aortic necks (n=17), large diameter (>28 mm) aortic necks (n=4), angulated (>60°) necks (n=3), and small (<15 mm) external iliac arteries (n=21). Outcomes evaluated included survival, endoleak, aneurysm expansion >5 mm, secondary intervention, stent-graft migration, and graft thrombosis. The overall technical success rate was 100%. Nineteen (17.1%) patients experienced perioperative complications. After a mean follow-up of 6 months (range 0.1-16), mortality in the series was 4.5%: 1 perioperative death (multisystem organ failure) and 4 (3.6%) late deaths (3 cardiac, 1 cancer). Clinical and imaging follow-up past the perioperative period were available in 107 (96.4%) and 99 (89.2%) patients, respectively. Among the latter, 9 (9.1%) had a type II endoleak on the first scan; 4 resolved spontaneously. Three (3.0%) patients developed graft limb thrombosis in follow-up; one required an intervention. There was no graft migration, aneurysm expansion, secondary intervention for endoleak, aneurysm rupture, or conversion. Early results from this prospective multicenter registry indicate that the Endurant stent-graft is a safe option for elective EVAR in selected AAA patients. Longer follow-up is required to determine the durability of these outcomes.Journal of Endovascular Therapy 02/2012; 19(1):58-66. DOI:10.1583/11-3622.1 · 3.59 Impact Factor