Bifurcated Stent Graft Research Articles

Effects of flat, parabolic and realistic steady flow inlet profiles on idealised and realistic stent graft fits through Abdominal Aortic Aneurysms (AAA)

Computational fluid dynamics modelling of bifurcated stent grafts positioned across Abdominal Aortic Aneursysms (AAAs) is influenced significantly by the boundary conditions and geometry. To assess these influencing factors, simulations using three different steady inlet profiles and two geometries were run. The steady velocity inlet profiles (flat, parabolic and realistic) were used as input boundary conditions with a constant pressure outlet for each model. The geometry of an out-of-plane realistic stent graft model, fitted to the internal geometry of an AAA (a realistic geometry generated from CT scans) was compared to an idealised geometry of an in-plane model. It was found that the realistic boundary condition when applied to the idealised model had a 5% difference in outlet flow rates when compared to flat and parabolic inlet profiles, while the realistic models had an 11–16% difference. The blood flowed in a parallel streamlined fashion for all the idealised models with slight recirculation for the realistic boundary condition. All realistic models had significant recirculation and flowed in a left-handed helix motion in the proximal end and left leg and in a right-handed helix motion in the right leg. The drag force was unidirectional in the idealised models, while it was found to act in all three directions for the realistic models with a 26% increase over the idealised models. It was concluded that geometry has the greatest influence on the outlet flow rates, flow patterns and drag forces. Input boundary condition cause variations in the skewness and recirculation of the flow throughout the models.

Midterm outcome of endovascular repair of ruptured abdominal aortic aneurysms

We sought to analyze the clinical and morphologic outcomes of bifurcated stent grafts in patients with ruptured aortoiliac aneurysms at midterm follow-up. Thirty-seven patients (4 women; mean age, 73 years; mean abdominal aortic aneurysm [AAA] diameter, 77 mm) underwent endovascular abdominal aneurysm repair between June 1997 and July 2003 for ruptured AAA. Devices inserted were as follows: Vanguard (Boston Scientific, Natick, Mass; n = 7), Excluder (W.L. Gore, Flagstaff, Ariz; n = 25), Talent (Medtronic Vascular, Santa Rosa, Calif; n = 2), and Zenith (Cook Inc, Bloomington, Ind; n = 3). Except for the adjunct postimplantation computed tomographic scanning, the imaging follow-up was the same as for nonruptured AAAs. The mean follow-up period was 24 months (range, 1-59) months. Thirty-day mortality was 10.8%. Three patients died during the follow-up of non-AAA-related causes. One patient was converted early for presumed renal overstenting. The late conversion rate was 9% because of stent graft migration (n = 2) or infection (n = 1). Freedom from endoleak was 57% +/- 8.5% and 48.8% +/- 9% at 2 and 4 years, respectively. Seventeen secondary interventions were performed during the follow-up period, 41% of these within 1 month of stent graft placement. Endoleaks, primary or secondary, were responsible for 58.8% of these interventions. The cumulative risk of a secondary intervention was 35.3% +/- 9% at 2 years and 44.6% +/- 11% at 3 years. Aneurysmal sac shrinkage was observed in 30.8% +/- 9.1% and sac enlargement was observed in 15.3% +/- 10.8% at 2 years. Endoluminal devices are able to convert the acute life-threatening situation of ruptured AAA to a controlled situation that results in good patient survival at midterm follow-up.

Iliac fixation length and resistance to in-vivo stent-graft displacement

Migration of endovascular stent grafts has been related to the security of proximal device fixation to the aortic neck. This study evaluated the importance of iliac fixation in preventing longitudinal in vivo device displacement of a modular, externally supported stent graft. Experimental ovine infrarenal aneurysms (n = 8) were treated with a fully supported, modular, bifurcated stent graft (AneuRx, Medtronic, Santa Rosa, Calif). Minimum iliac fixation length (1 cm) was used in four animals and iliac extender modules were used to achieve maximum iliac fixation in four animals. Suture anastomosis of bifurcated polyester grafts to the infrarenal aorta served as controls (n = 8). Aortic grafts were displaced in vivo by applying downward traction to a guidewire that was passed over the iliac flow divider and brought out both femoral arteries. The displacement force needed to initiate stent-graft migration was recorded and compared with the force needed to disrupt the sutured anastomosis. There was no difference in animal weight (88.8 +/- 2.5 kg vs 87.5 +/- 2.9 kg), aortic neck diameter (12.7 +/- 0.9 mm vs 13.4 +/- 1.1 mm), aortic neck length (23.2 +/- 0.9 mm vs 21.8 +/- 2.4 mm), experimental aneurysm size (24.7 +/- 1.1 mm vs 24.2 +/- 2.0 mm), or iliac artery diameter (9.0 +/- 1.5 mm vs 9.3 +/- 0.5 mm) among the groups. Iliac fixation length was 31.0 +/- 0.3 mm in the maximum iliac fixation group and 11 +/- 0.25 mm in the minimum fixation group (P < .0001). Peak displacement force to initiate migration was 30.2 +/- 5.5 N (range, 25 to 38) in animals with maximum iliac fixation compared with 18.1 +/- 3.7 N (range, 13 to 21) in those with minimum fixation (P = .01). The force needed to disrupt the control surgical anastomosis was 40.6 +/- 7.5 N (range, 31 to 50) (P < .01). Maximizing iliac fixation length increases the longitudinal in vivo force needed to displace a fully supported stent graft by 67%. This suggests that increasing iliac fixation length may reduce the long-term risk of migration in patients undergoing endovascular aneurysm repair.

EVAR to reduce mortality and morbidity in treatment of ruptured abdominal aortic aneurysms: A 7-years single center experience with bifurcated stent grafts

Background: Morbidity and mortality of conventional open surgery for ruptured abdominal aortic aneurysm (rAAA) remained high during the last 50 years. Small studies have shown promising results of endovascular aneurysm repair (EVAR) for the treatment of rAAA. We report the results of the biggest series of EVAR for rAAA worldwide treated with bifurcated stentgrafts (SG).

Endograft repair of spontaneous infrarenal abdominal aortic dissection

A 71-year-old man with a history of hypertension and a recent myocardial infarction experienced a sudden periumbilical and back pain. Abdominal tenderness was found at physical examination, with no changes in electrocardiogram and serial enzyme determinations. Computed tomographic angiography (CTA) showed a normal thoracic aorta, an infrarenal aortic dissection extending into the left common iliac artery and a contralateral iliac occlusive disease (A, Cover). Although antihypertensive therapy was administered, the patient had persistent pain; subsequently, he underwent endovascular repair with a bifurcated stent graft (Talent, Medtronic Ave, Santa Rosa, Calif) introduced via the left femoral artery through the introducer sheath. Because the contralateral iliac artery was not suitable for iliac limb deployment, an occluding covered stent was then positioned, and a 8-mm ePTFE femorofemoral bypass grafting was done to perfuse the right leg. The patient was discharged on postoperative day 4. A CTA postprocedural scan was performed with a multidetector device; a complete exclusion of dissection (B) and patency of femorofemoral bypass was observed. At 6 months, he remains symptom-free; the CTA scans with 3-dimensional volume rendering reconstruction show a normal morphology of abdominal aorta and femorofemoral reconstruction, with retrograde filling of right iliac arteries (C).

First experience in human beings with a permanently implantable intrasac pressure transducer for monitoring endovascular repair of abdominal aortic aneurysms

Endovascular stent graft repair of abdominal aortic aneurysms (AAAs) prevents rupture by excluding the aneurysm sac from systemic arterial pressure. Current surveillance protocols after endovascular aneurysm repair (EVAR) follow secondary markers of sac pressurization, namely, endoleak and sac enlargement. We report the first clinical experience with the use of a permanently implantable, ultrasound-activated remote pressure transducer to measure intrasac pressure after EVAR. Over 7 months, 14 patients underwent EVAR of an infrarenal abdominal aortic aneurysm with implantation of an ultrasound-activated remote pressure transducer fixed to the outside of the stent graft and exposed to the excluded aortic sac. Twelve patients received modular bifurcated stent grafts, and 2 patients received aortouniiliac devices. Intrasac pressures were measured directly with an intravascular catheter and by the remote sensor at stent-graft deployment. Follow-up sac pressures were measured with a remote sensor and correlated with systemic arterial pressure at every follow-up visit. Mean follow-up was 2.6 +/-1.9 months. Excellent concordance was found between catheter-derived and transducer-derived intrasac pressssure intraoperatively. Pulsatile waveforms were seen in all functioning transducers at each evaluation interval. One implant ceased to function at 2 months of follow-up. In 1 patient a type I endoleak was diagnosed on 1-month computed tomography (CT) scans; 3 type II endoleaks were observed. Those patients with complete exclusion of the aneurysm on CT scans had a significant difference in systemic and sac systolic pressures initially (P <.001) and at 1 month (P <.001). Initial sac diastolic pressures were higher than systemic diastolic pressures (P <.001). The ratio of systemic to sac systolic pressure increased over time in those patients with complete aneurysm exclusion ( P <.001). Four of 6 patients with no endoleak and greater than 1-month follow-up had diminution of sac systolic pressure to 40 mm Hg or less by 3 months. This is the first report of a totally implantable chronic pressure transducer to monitor the results of EVAR in human beings. Aneurysm exclusion leads to gradual diminution of sac pressure over several months. Additional clinical follow-up will be necessary to determine whether aneurysm sac pressure monitoring can replace CT in the long-term surveillance of patients after EVAR.

A mathematical model to predict the in vivo pulsatile drag forces acting on bifurcated stent grafts used in endovascular treatment of abdominal aortic aneurysms (AAA)

A mathematical model to predict the in vivo pulsatile drag forces acting on bifurcated stent grafts used in endovascular treatment of abdominal aortic aneurysms (AAA)

Endovascular Repair of Paraanastomotic Aneurysms after Previous Open Aortic Prosthetic Reconstruction

The aim of this study was to evaluate the effectiveness of endovascular repair of anastomotic and true aortic and iliac aneurysms occurring after prior polyester graft repair for abdominal aortic aneurysms (AAA) or aortoiliac obstructive disease. Between July 1999 and January 2003, 14 patients underwent endovascular treatment of aortic pseudoaneurysms (n = 6) or iliac aneurysms (2 patients with pseudoaneurysms and 6 patients with true aneurysms) occurring 4 to 18.4 years (mean, 8.8 years) after open aortic surgery. No patient had symptoms or positive parameters for infection of the original polyester graft. Eleven patients, including one patient with both a proximal anastomotic and a true iliac aneurysm, were treated with AneuRx (n = 8), Talent (n = 2), or Quantum LP (n = 1) bifurcated stent grafts. Three patients with an infrarenal anastomotic pseudoaneurysm were treated with a tube stent graft (Talent [n = 2] and AneuRx [n = 1]). Endovascular stent grafts were successfully inserted in all patients. Procedure-related complications or death was not seen. During a median follow-up of 12 months (range, 3-40) all anastomotic and/or true aneurysms treated with bifurcated stent grafts maintained excluded. However, two out of three patients, treated with a tube graft for proximal aneurysm exclusion, were converted. In both patients the tube stent graft did not migrate from the level of the renal arteries but fixation failed between the stent graft and the previous polyester graft, creating endotension in the thrombus of the aneurysm sac. In one of these patients the old anastomotic aneurysm ruptured 16 months after stent graft placement and the patient died 1 day after conversion because of mesenterial ischemia. At 1 year follow-up the second patient was converted successfully after enlargement of his anastomotic aneurysm due to similar disconnection between the stent graft and the polyester graft. From this experience with endovascular stent grafts, we conclude that these can be used successfully to exclude anastomotic or true aneurysms after open aortic surgery. Exclusion of aneurysms at the proximal anastomosis with tube stent grafts is apparently not durable because of the insecure distal fixation in polyester grafts. Endovascular repair with bifurcated stent grafts, however, seems to be effective at midterm follow-up.

Aortitis and bilateral ureteral obstruction after endovascular repair of abdominal aortic aneurysm

A bifurcated stent graft was used to treat an asymptomatic 5.4-cm abdominal aortic aneurysm in a 76-year-old man. No endoleaks or inflammatory changes were seen on the 1-month follow-up computed tomography scan. Five months later the patient had acute renal failure and ureteral obstruction secondary to significant inflammatory changes in the aneurysm wall. After bilateral ureteral stenting, conservative treatment included tamoxifen and steroid therapy. The patient remains symptom-free, and at 2-year follow-up a computed tomography scan demonstrated decreased inflammation and shrinkage of the excluded abdominal aortic aneurysm.

A mathematical model to predict the in vivo pulsatile drag forces acting on bifurcated stent grafts used in endovascular treatment of abdominal aortic aneurysms (AAA)

Endovascular treatment of abdominal aortic aneurysms (AAA) is a promising new alternative to the traditional surgical repair. However, the endovascular approach suffers problems such as stent graft migration, endoleaks and stent mechanism breakage. Fatigue failure is believed to be the major cause of stent graft migration and device breakage. Knowledge of the in vivo forces acting on such devices is a basic requirement for the design of a successful endovascular device. Using a Fourier series trigonometric fit of a typical pressure and flow relationship, a mathematical model, using the control volume method, was developed to predict the pulsatile drag forces acting on various bifurcated stent graft geometries. It was found that for an iliac angle of 30°, a proximal diameter of 24 mm and an iliac diameter of 12 mm, the drag force varied, over the cardiac cycle, between 3.9 and 5.5 N in the axial direction. It was noted that for a specific iliac angle the drag force variation with proximal diameter approximates a quadratic fit, with an increase in proximal diameter producing an increase in drag force. The more compliant the aorta the higher the drag force. Previously published results demonstrated the axial loads (axial drag forces) required for stent graft migration for certain stents types are lower than the drag forces calculated in this study. It is believed that the results of this study can provide guidelines for the quantitative analyses of the in vivo drag forces experienced by stent grafts and could therefore be used as design criteria for such devices.

A Comparison of AneuRx Aortic Cuff and Zenith Distal Flare Exclusion of Common Iliac Artery Ectasia for Endovascular Aneurysm Repair

Stent-grafts are ideally terminated within the common iliac artery (CIA). However, CIA ectasia may require hypogastric artery occlusion, with stent-graft extension to the external iliac artery. Alternatively, the diameter of the distal stent-graft may be increased, or flared, to allow exclusion of the abdominal aortic aneurysm. This report details the authors' experience with this technique. Forty-one patients received bifurcated stent-grafts (BSG): 20 received an AneuRx device, and 21 received a Zenith device. CIA ectasia (diameter 15-25 mm) was treated with a distal flare of 2-4 mm greater than the CIA diameter. Patients were followed up with computed tomography scan at 1, 6, and 12 months. Statistical analysis was performed using ANOVA within groups and unpaired two-tailed t test between groups. A p value of < 0.05 was considered significant. Eight of 20 patients (40%) (11 CIA) received an AneuRx device and 13/21 (62%) (17 CIA) received a Zenith device, with a distal flare. Values are (n) mean (mm) +/- SE. There were no deaths, endoleaks, migrations, or conversions to open repair. Follow-up mean was 24.7 and 20.6 (range 15-28) months for AneuRx and Zenith groups, respectively. In comparing initial and 12-month CIA diameters, AneuRx grafts 20 +/-0.8 vs 21.5 +/-1.0 were not significantly different, p = 0.2, nor was the same comparison for Zenith, 17 +/-0.5 vs 19.1 +/-0.4, significant, p = 0.57. At a mean follow-up of 12 months, distal flare of iliac limbs with either AneuRx or Zenith devices affords a seal for CIA ectasia and/or aneurysms complicating EVAR.

Effect of suprarenal versus infrarenal aortic endograft fixation on renal function and renal artery patency: a comparative study with intermediate follow-up

Suprarenal fixation of aortic endografts appears to be a safe option in patients with a short or conical proximal aortic neck. However, concern persists regarding the long-term effect on renal function when renal artery ostia are crossed by the uncovered stent. We investigated the effect of suprarenal versus infrarenal endograft fixation on renal function and renal artery patency after endovascular aortic aneurysm repair. Records of 91 patients who underwent endovascular aortic aneurysm repair with a modular bifurcated stent graft between November 1999 and January 2002 were reviewed retrospectively. Two patients receiving dialysis because of chronic renal failure were excluded. Infrarenal fixation was used in 57 patients (group 1), and suprarenal fixation was used in 32 patients (group 2). In two patients in group 1 a Gianturco Z stent was inserted transrenally because of intraoperative proximal type I endoleak, and data for these patients were excluded from analysis. Follow-up evaluation was performed at 1, 6, and 12 months, and yearly thereafter, and included clinical assessment, measurement of serum creatinine concentration (SCr), and computed tomography angiography, per standard protocol. Median follow-up was 12 months (range, 1-36 months). There was no statistically significant difference in patient demographic data, aneurysm size, or preoperative risk factors. Median SCr was significantly higher in group 2 (suprarenal fixation) than in group 1 (infrarenal fixation) preoperatively (1.2 mg/dL [range, 0.6-2.3 mg/dL] vs 0.9 mg/dL [range, 0.6-1.9 mg/dL], P =.008) and at 1 month postoperatively (1.1 mg/dL [range, 0.8-5.6 mg/dL] vs 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.045). There was a significant increase in median SCr in both groups at 1 month postoperatively (group 1, 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.05; group 2, 1.1 mg/dL [range, 0.8-5.6 mg/dL] [mean SCr, 1.35 mg/dL vs 1.15 mg/dL, respectively], P <.05). In group 1 SCr was increased significantly at 6 and 12 months (P <.001), whereas in group 2 SCr also increased at 6 and 12 months, but not significantly. The change in SCr over time was not significantly different between the two groups. In two of 32 patients in group 2, renal artery occlusion developed, associated with perfusion defects in renal parenchyma and persistently elevated SCr. Analysis of renal artery patency did not demonstrate any association between patency and treatment. No patient developed hypertension during follow-up. Suprarenal endograft fixation does not lead to significant renal dysfunction, and renal artery occlusion is uncommon within 12 months. A larger study with longer follow-up is essential to determine overall effects on renal function and renal artery patency.

Femoral incision morbidity following endovascular aortic aneurysm repair.

Currently available aortic stent-grafts require bilateral femoral incisions for device deployment. The incidence of morbidity (infection, lymphatic complications, breakdown) of vertical, infrainguinal incisions used in endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs) was assessed, and the natural history of asymptomatic groin fluid collections following such procedures was determined. Between June 1999 and February 2001, 77 consecutive patients underwent EVAR for AAAs utilizing bilateral vertical femoral incisions. Fifty-nine (77%) bifurcated stent-grafts (BSGs), and 18 (23%) aortouniiliac (AUI) devices, with femorofemoral bypass were performed. Patients returned at 2 weeks, 1 month, and 6 months for physical examination, and 1 month and 6 months for abdominal and pelvic computed tomography (CT) scans. The presence of fluid collections was determined from the dictation report of the attending radiologist. Data are reported as (n) mean +/-SE. Patient characteristics were compared using Fisher's exact test; p<0.05 considered significant. There were 72 males and 5 females, age 75 +/-6.4 years and aneurysm size (77) 5.6 +/-0.8 cm. There were no cases of wound breakdown or lymph fistula. Wound infections occurred in 3/150 incisions (2%), 2/34 AUI incisions (6%), and 1/116 BSG incisions (0.86%). There was no statistical difference (p=0.13) between graft types (BSG vs AUI). All infections were diagnosed clinically before the 1-month CT scan, treated without operative intervention or hospitalization, and resolved. There was a significant decrease in the BSG group and overall in asymptomatic wound fluid collections from 1 to 6 months postoperatively. At 1 and 6 months, respectively, the BSG group had 17 (14.6%) and 3 (2.6%) fluid collections out of 116 incisions (p=0.003); the AUI group had 6 (17.6%) and 1 (2.9%) fluid collection(s) out of 34 incisions (p=0.13); and overall 23 (15.3%) and 4 (2.6%) out of 150 incisions (p=0.004). The present study demonstrates that bilateral vertical femoral incisions used in EVAR have a wound infection rate of 2.0%. Infections are usually detected and treated clinically and empirically without the need for hospitalization or surgery. Asymptomatic groin wound fluid collections resolve significantly within 6 months without intervention. Therefore, surgical femoral artery exposure adds little morbidity to the endovascular repair of abdominal aortic aneurysms.

Efficacy of ultrasound scan contrast agents in the noninvasive follow-up of aortic stent grafts

Computed tomographic angiography (CTA) is currently the most commonly used technique for postoperative surveillance to detect endoleaks after endovascular stent graft repair of abdominal aortic aneurysms. We have evaluated the efficacy of duplex ultrasound scan with the addition of an ultrasound scan contrast agent in documenting endoleaks and compared these results with CTA. Conventional duplex ultrasound scan with color Doppler imaging (CDI) was first done as part of routine postoperative surveillance. After the CDI study, a 1-mL bolus of ultrasound scan contrast was given via an antecubital vein, followed by a 5-mL flush with normal saline solution. The duplex ultrasound scan evaluation of the stent graft was repeated once the contrast agent was circulating throughout the blood pool, with tissue harmonic imaging to optimize visualization of the contrast agent. Status of the stent graft, the presence or absence of any endoleak, and whether these endoleaks were graft related (group I) or arterial branch related (group II) were recorded. Findings were compared with CTA studies done within a 2-week period of the ultrasound scan examination. Twenty patients were evaluated, 18 with modular stent grafts and two with unibody bifurcated stent grafts. Patients had a mean age of 74.5 +/- 7.6 years; 19 were male, with only one female. All stent grafts remained widely patent with normal aortoiliac flow hemodynamics. Duplex ultrasound scan with contrast identified all eight of the endoleaks seen with CTA and was able to determine whether they were group I or group II leaks. In two patients, ultrasound scan with contrast detected small endoleaks at the proximal graft attachment site, with extravasation of contrast into the aneurysm sac during systole. These endoleaks were not seen with CTA but were confirmed with conventional angiography at the time of endovascular closure. Standard duplex ultrasound scan with CDI failed to identify four of the 10 endoleaks in patients with technically difficult conditions. Duplex ultrasound scan, when used with an intravenously administered ultrasound scan contrast agent in the noninvasive follow-up of patients with aortic stent grafts, appears to provide good sensitivity to the presence and type of endoleaks, even in patients with technically difficult conditions not amenable to conventional duplex ultrasound scan with CDI.

Treatment of thoracoabdominal aneurysm with self-expandable aortic stent grafts

A 67-year-old man with a large thoracoabdominal aneurysm was treated utilizing the endovascular approach with multiple stent graft implantation. The proximal thoracic and distal abdominal necks of the aneurysm had favorable anatomy for insertion of multiple endovascular stents. The proximal end was located just distal to the left subclavian artery, and stents were placed to the region of the celiac axis. The infrarenal aneurysm was treated with a bifurcated stent graft to the iliac arteries. The patient has had a smooth post-stent insertion course and remains well after 3 months of follow-up.

Intra-aneurysm Sac Pressure – The Holy Grail of Endoluminal Grafting of AAA

Objectives: to relate intra-aneurysm sac pressure during endoluminal AAA repair to early and late endoleak, as well as to the aneurysm size upon follow-up.Design: prospective clinical investigation.Methods and patients: in 46 patients who had their AAAs treated by a stent graft (group I), intra-operative pressure measurement was performed (aorto uni-iliac stent grafts: 25 cases, bifurcated stent grafts: 21 cases). In 18 patients with open repair (group II) flow in the inferior mesenteric artery, and the pressure in the aneurysm sac was measured, before and after aortic and iliac cross clamping. Values are given in median with range.Results: in group I, complete exclusion of AAA (no endoleak on intra-operative control angiogram) resulted in a statistically significant decrease in mean sac pressure from 74 (55–101) to 47 (4–104)mmHg. Pulse pressure reduced from 67 (34–103) to 8 (0–74)mmHg. In 11 patients a proximal type I endoleak was sealed by balloon modeling, after which the mean sac pressure reduced from 63 (14–91) to 52 (4–74)mmHg (n.s. versus patients with primary seal). Intra-operative pressure did not correlate with change in AAA diameter during twelve months follow-up. In group II, cross clamping of the proximal aorta significantly reduced mean sac pressure to 32 (21–55)mmHg, and the pulse pressure to 0 (0–13)mmHg (p<0.05). Subsequent cross clamping of the iliac arteries did not significantly change the pressures.Conclusions: measurement of intra-aneurysm sac pressure can help to detect and treat endoleaks during endoluminal grafting. However, the intra-operative sac pressure did not predict the fate of aneurysm during follow up. Compared to open repair of AAA, the sac pressure after endoluminal grafting remains significantly higher, in relation to pulse pressure.

Late endoleak after endovascular repair of an abdominal aortic aneurysm with multiple proximal extender cuffs

Late onset graft or attachment site-related endoleaks may be hazardous, and early identification of patients at risk is important. We describe a patient who underwent implantation of a bifurcated stent graft 5.5 cm below the renal arteries because of a technical error with three extender cuffs implanted proximally to bridge the gap. During the 1st year, aneurysm diameter decreased from 68 to 52 mm. After 1 year, the patient had an acute endoleak develop, which originated between two of the extender cuffs and which was accompanied by severe abdominal pain and reexpansion of the aneurysm. This endoleak was treated with insertion of an additional bifurcated stent graft within the extender cuff segment. The patient has been subsequently followed for 6 months and has had no endoleak or symptoms, and aortic diameter has decreased once again to 55 mm.

The AneuRx stent graft: Four-year results and worldwide experience 2000

Objective: The objective was to review the current results of endovascular abdominal aortic aneurysm repair with the AneuRx stent graft and to determine the effectiveness of the device in achieving the primary objective of preventing aneurysm rupture. Methods: The outcome of all patients treated during the past 4 years in the U.S. AneuRx clinical trial was determined, and the worldwide clinical experience was reviewed. Results: A total of 1192 patients were treated with the AneuRx stent graft during all phases of the U.S. Clinical Trial from June 1996 to November 1999, with follow-up extending to June 2000. Ten (0.8%) patients have had aneurysm rupture, with most ruptures (n = 6) occurring in 174 (3.4%) patients treated with an early stiff bifurcation stent graft design used in phase I and in the initial stages of phase II. Since the current, flexible, segmented bifurcation stent graft design was introduced, four (0.4%) ruptures have occurred among 1018 patients treated. Of these, one was during implantation, two were placed too far below the renal arteries, and one patient refused treatment of a type I endoleak. Kaplan-Meier analysis of all 1192 patients treated with the AneuRx stent graft including both stent graft designs revealed the patient survival rate to be 93% at 1 year, 88% at 2 years, and 86% at 3 years, freedom from conversion to open repair to be 98% at 1 year, 97% at 2 years, and 93% at 3 years, and freedom from secondary procedure to be 94% at 1 year, 92% at 2 years, and 88% at 3 years. Freedom from aneurysm rupture with the commercially available segmented bifurcation stent graft was 99.7% at 1 year, 99.5% at 2 years, and 99.5% at 3 years. The presence or absence of endoleak on contrast computed tomography scanning after stent graft placement was not found to be a significant predictor of long-term outcome measures. Worldwide experience with the AneuRx device now approaches 10,000 patients. Conclusions: Endovascular management of abdominal aortic aneurysms with the AneuRx stent graft has markedly reduced the risk of aneurysm rupture while eliminating the need for open aneurysm surgery in 98% of patients at 1 year and 93% of patients at 3 years. The device was effective in preventing aneurysm rupture in 99.5% of patients over a 3-year period. The overall patient survival rate was 93% at 1 year and 86% at 3 years. (J Vasc Surg 2001;33:S135-45.)

The Value of Intraoperative Intravascular Ultrasound for Determining Stent Graft Size (Excluding Abdominal Aortic Aneurysm) with a Modular System

Since the introduction of endovascular stent grafts at our institution we have used intraoperative intravascular ultrasound (IVUS) to definitively determine stent graft size. In this study, expected stent graft size, based on preoperative helical CT scan measurements, was compared with the actual final size, based on intraoperative IVUS measurements. Between December 1996 and January 1998, 54 patients were treated with an AneuRxTM bifurcated stent graft. Preoperatively all patients underwent angiography and helical CT scanning. Expected stent graft size was determined according to these measurements. The final stent graft size was based on IVUS measurements acquired during the procedure. Differences in expected and final size were compared and follow-up endoleaks were also noted. Differences in diameter measurements between CT and IVUS were compared using the paired Student's t-test. Differences in expected and chosen stent graft length were compared using the McNemar's test for paired proportions of binomial outcomes. Our results showed that helical CT scanning overestimates diameter and underestimates length. This underestimation of length is explained by the tortuosity of the aorta and iliac arteries while using axial slices of the CT scan. The last-minute corrections based on the intraoperative IVUS measurements did not result in a high incidence of endoleaks at fixation zones. In our opinion, the possibility of making final corrections in the choice of diameter or length of the stent graft is the additional value of intraoperative IVUS.

Endovascular aneurysm repair in high-risk patients

Purpose: The purpose of this study was to evaluate the role of endovascular aneurysm repair in high-risk patients. Methods: The elective endovascular repair of infrarenal aortic aneurysm was performed in 116 high-risk patients with either custom-made or commercial stent grafts. The routine follow-up examination included contrast-enhanced computed tomography (CT) before discharge, at 3, 6, and 12 months, and annually thereafter. Patients with endoleak on the initial CT underwent re-evaluation at 2 weeks. Those patients with positive CT results at 2 weeks underwent endovascular treatment. Results: Endovascular repair was considered feasible in 67% of the patients. The mean age was 75 years, and the mean aneurysm diameter was 6.3 cm. The American Society of Anesthesiologists grade was II in 3.4%, III in 65.5%, IV in 30.1%, and V in 0.9%. There were no conversions to open repair. Custom-made aortomonoiliac stent grafts were implanted in 77.6% of the cases, custom-made aortoaotic stent grafts in 11.2%, and commercial bifurcated stent grafts in 11.2%. The 30-day rates of mortality, major morbidity, and minor morbidity were 3.4%, 20.7%, and 12%, respectively, in the first 58 patients and 0%, 3.4%, and 3.4%, respectively, in the last 58. The late complications included five cases of stent graft kinking, two cases of femorofemoral graft occlusion, and three cases of proximal stent migration, one of which led to aneurysm rupture. At 2 weeks after repair, endoleak was present in 10.3% of the cases. All the type I (direct perigraft) endoleaks underwent successful endovascular treatment, whereas only one type II (collateral) endoleak responded to treatment. The technical success rate at 2 weeks was 86.2%, and the clinical success rate was 96.6%. The continuing success rate was 87.9%. Seventeen patients died late, unrelated deaths. Conclusion: Endovascular aneurysm repair is safe and effective in patients at high risk, for whom it may be the preferred method of treatment. (J Vasc Surg 2000;31:122-33.)