The effect of endovascular aortic stents placed across the renal arteries

Endograft Repair of an Aortic Pseudoaneurysm following Gunshot Wound Injury: Impact of Imaging on Diagnosis and Planning of Intervention

Purpose:

To describe the endovascular treatment of a gunshot injury to the visceral aorta and the role of various imaging modalities in the staging and planning of the endograft procedure.

Methods and Results:

The bullet entered the aorta posteriorly beneath the origin of the superior mesenteric artery and traversed the wall in a tangential manner entering the lumen proximal to the renal arteries. Intravascular ultrasound (IVUS) imaging and spiral computed tomography (CT) identified the injury that the initial angiograms failed to demonstrate. Combined use of IVUS and CT imaging enabled observation of the evolution of a pseudoaneurysm until an interval when endograft exclusion was possible. A stent-graft was customized based on precise IVUS and CT dimensional data and implanted successfully through an arteriotomy in the common femoral artery 3 weeks after the initial injury. Three-month follow-up imaging demonstrated continued exclusion of the pseudoaneurysm, and the patient remains well at 16 months.

Conclusions:

IVUS and spiral CT scans were instrumental in identifying an arteriographically undetected aortic injury. The combined imaging modalities also helped determine the timing for the endovascular procedure and provided the precise measurements for device fabrication and deployment.

Endovascular Repair of Abdominal Aortic Aneurysm Using the EVT Device: Limited Increased Utilization with Availability of a Bifurcated Graft

Purpose:

To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs).

Methods:

One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed.

Results:

Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous.

Conclusions:

Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

Endovascular AAA Exclusion: Will Stents with Hooks and Barbs Prevent Stent-Graft Migration?

Purpose:

To investigate if stents with hooks and barbs will improve stent-graft fixation in the abdominal aorta.

Methods:

Sixteen- to 24-mm-diameter Dacron grafts were deployed inside cadaveric aortas. The grafts were anchored by stents as in endovascular abdominal aortic aneurysm repair. One hundred thirty-seven stent-graft deployments were carried out with modified self-expanding Z-stents with (A) no hooks and barbs (n = 75), (B) 4 5-mm-long hooks and barbs (n = 39), (C) 8 10-mm-long, strengthened hooks and barbs (n = 19), or (D) hooks only (n = 4). Increasing longitudinal traction was applied to determine the displacement force needed to extract the stent-grafts. The radial force of the stents was measured and correlated to the displacement force.

Results:

The median (interquartile range) displacement force needed to extract grafts anchored by stent A was 2.5 N (2.0 to 3.4), stent B 7.8 N (7.4 to 10.8), and stent C 22.5 N (17.1 to 27.9), p < 0.001. Both hooks and barbs added anchoring strength. During traction, the weaker barbs were distorted or caused intimal tears. The stronger barbs engaged the entire aortic wall. The radial force of the stents had no impact on fixation, while aortic calcification and graft oversizing had marginal effects.

Conclusions:

Stent barbs and hooks increased the fixation of stent-grafts tenfold, while the radial force of stents had no impact. These data may prove important in future endograft development to prevent stent-graft migration after aneurysm exclusion.

Endovascular Repair of Abdominal Aortic Aneurysm Using a Pararenal Fenestrated Stent-Graft

Purpose:

To report an unusual case of endovascular abdominal aortic aneurysm (AAA) exclusion in which a fenestrated stent-graft was used to seal a proximal Type I endoleak.

Methods and Results:

An 84-year-old man with a 6.0-cm AAA underwent an aortomonoiliac aneurysm exclusion procedure that was complicated by a proximal endoleak. Because the patient had no right kidney, an additional stent-graft was designed to cover the right renal artery stump while preserving left renal perfusion through a fenestration in the graft material. This approach was successful in obliterating the endoleak around the proximal attachment site, but flow through the lumbar arteries remained.

Conclusions:

The use of a fenestrated stent-graft is feasible, but the type of fenestration in this case has limited applicability owing to the rarity of patients with suitable anatomy.

Changing Aneurysmal Morphology after Endovascular Grafting: Relation to Leakage or Persistent Perfusion

Purpose:

To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors.

Methods:

Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12).

Results:

At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion.

Conclusions:

The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.

Endovascular Repair of Aortic Aneurysms in the Presence of a Horseshoe Kidney

Purpose:

To report two cases of endovascular aortic aneurysm exclusion in patients with a horseshoe kidney.

Methods and Results:

Two male patients, one with a known horseshoe kidney and history of multiple previous laparotomies, presented with abdominal aortic aneurysms of approximately 6-cm diameter. Each was treated with a tapered aortomonoiliac polytetrafluoroethylene graft secured proximally with a Palmaz balloon-expandable stent. The endograft was sutured distally to a Dacron femorofemoral crossover graft. An anomalous renal vessel was sacrificed in one case. The aneurysms were successfully excluded, and the patients recovered without sequelae.

Conclusions:

Endovascular repair should be considered as a treatment option in patients with aortic aneurysm in the presence of a horseshoe kidney, particularly if the renal vasculature can be wholly preserved.

Placement of endovascular stent across the branching arteries: long-term serial evaluation of stent-tissue responses overlying the arterial orifices in an experimental study

PURPOSE

This study was designed to investigate the effects of stenting across the branching arteries on the patency and stent-tissue responses over the branching arterial orifices.

METHODS

Thirteen dogs were observed after placing aortic stents across the celiac arteries (CA), superior mesenteric arteries (SMA), and renal arteries (RA). The animals were grouped according to stent types: large-cell group (n = 6) and small-cell group (n = 7). Angiography was performed to evaluate the branching artery patency at 2, 6, and 12 months after stent insertion, and the stent-tissue responses covering the orifices were evaluated on histopathologic examination.

RESULTS

All branching arteries were patent on follow-up angiography; however, three patterns of stent-tissue responses over the orifices were observed: neointimal layering, bridging septa, and papillary hyperplasia. Although neointimal layering and bridging septa were evenly observed, severe papillary hyperplasia was more frequent at SMA and CA than RA. Four RA showed less than 50% ostial patency, and localized infarct was observed in six kidneys (24%). The ostial patency tended to decrease with small-cell stent during the follow-up period.

CONCLUSIONS

Various stent-tissue responses over the branching artery orifices are induced by the aortic stent covering the branching arteries and may not be easily detected by conventional angiography. Subclinical renal infarct also may occur despite patent renal angiography.

How to design the optimal stent graft--what have we learnt?

It is now more than 20 years since the first report of stent graft insertion in the human arterial system was published. The first "homemade" devices proved that the technique was possible but could not show any durability. Using these devices, it was possible to get a good seal but not a good anchorage. Not even the first generation of commercially available stent grafts proved to be durable. First after gaining knowledge about the forces acting on the stent graft, it was realized that attachment was important for the durability and the hooks and barbs or a longitudinal stability are needed to minimise the risk for distal migration. Not much of a difference in the overall performance is noticed between the ePTFE graft or the polyester graft or when comparing stainless steel stents with those made out of nitinol. The systems are made much more flexible and hydrophilic leading to a better performance and a greater chance of percutaneous approach. The optimal stent graft is not out on the market yet, but hopefully will come with further development.

Comparative analysis of renal function after treatment of infrarenal abdominal aortic aneurysms with a suprarenal fixation device as opposed to open surgery

We analyzed the repercussions on renal function between suprarenal endograft fixation and open surgery in the treatment of infrarenal abdominal aortic aneurysms (IAAAs) and determined the influential factors. Between 1999 and 2005, 59 IAAAs were treated with elective OS and 56 with SEF. The serum creatinine (Cr) level and its clearance were determined before the procedure, in the intensive care unit (ICU), on discharge, and after 1, 6, 12, and 24 months. A deterioration in renal function was considered to be a >30% increase in Cr or a Cr >2 mg/dL. A univariate statistical analysis and a logistical regression analysis were carried out to determine the predictive factors for repercussions on renal function. There were no statistically significant differences in the rate of renal exacerbation between the groups either on discharge (p = 0.52) or after 1 month (p = 0.483), 6 months (p = 0.451), 12 months (p = 0.457), and 24 months (p = 0.682). The only significant difference was that detected in the ICU (p = 0.033). Diabetes mellitus, time spent in the ICU, postoperative intubation time, intraoperative transfusion, and transfusion in the ICU were factors that influenced the deterioration of renal function in the univariate analysis. The only significant factor in the multivariate analysis was the need for transfusion in the ICU. Exacerbation of renal function occurred in both groups independently of treatment type. In the immediate postoperative period, hemodynamic deterioration is more frequent in the open surgery group. Renal exacerbation tended to disappear in both groups during follow-up.

Dynamic Cine-Computed Tomography Angiography Imaging of Standard and Fenestrated Endografts: Differing Effects on Renal Artery Motion

Different endograft configurations (fenestrated, transrenal, infrarenal) may varyingly affect aortic side branch movement. Renal artery motion was evaluated with 64-slice dynamic cine-computed tomography angiography before and after endovascular aneurysm repair in 16 patients (46 renal arteries). Center-of-mass displacement of the renals was determined per heartbeat for before repair for 3 different endografts; differences were compared, with significance at P < 0.5. Preoperative renal artery motion is significant (1.2 [SD 0.5] mm, range, 0.6-2.). Neither transrenal nor infrarenal endografts alter renal artery motion compared with before repair ( P < .05). Renal artery motion after fenestrated endovascular repair with renal stents reduces motion to 25% of the preoperative value (0.3 [SD, 0.1] mm, range, 0.2-0.5 mm; P = .01). Endograft implantation without stented side branches does not change renal artery motion, potentially allowing significant movement of the renal artery relative to the fenestration. Routine stenting of fenestrations limits postoperative renal artery motion to 0.3 mm, thereby preventing significant branch movement in relation the fenestration.

The Mid-term Effect of Bare Metal Suprarenal Fixation on Renal Function Following Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVE

The aim of this study was to assess the mid term effect of proximal bare metal fixation design on renal function in patients undergoing endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

Consecutive EVR patients for AAA from December 1995-2001 were included and grouped to either infrarenal (Group 1) or uncovered suprarenal (Group 2) fixation. Peri-operative renal function and at 6, 12 and 24 months was determined by serum creatinine (sCr mmol l(-1)) and Cockroft-Gault creatinine clearance (CrC ml min(-1)). Changes in renal function were compared using non-parametric analysis.

RESULTS

Of the 179 EVR procedures during this six-year period, paired renal data was available for 135 patients at a minimal follow-up of 6 months (Gp1, n = 63; Gp2, n = 72). Median pre-EVR sCr and CrC were 113, 57 in Group 1 and 108, 58 in Group 2, p = NS. There was no significant deterioration in renal function within or between either group at 2 years post-EVR: median sCr, CrC values were 118, 56 (Group 1) and 111, 56 (Group 2), all p = NS.

CONCLUSION

This study suggests mid-term renal function remains unaffected following EVR of AAA, irrespective of proximal fixation type. Designs to improve stent durability and EVR applicability do not appear to compromise renal function.

Endovascular Aneurysm Repair Alters Renal Artery Movement: A Preliminary Evaluation Using Dynamic CTA

PURPOSE

To observe the natural renal artery motion during cardiac cycles in patients with abdominal aortic aneurysm (AAA) and how the implantation of stent-grafts may distort this movement.

METHODS

Data on 29 renal arteries from 15 male patients (mean age 72.6 years, range 66-83) treated with Talent or Excluder stent-grafts were acquired using an electrocardiographically (ECG)-gated dynamic 64-slice CT scanner. ECG-triggered retrospective reconstructions were made at 8 equidistant time points over the R-R cardiac cycle. The gated datasets were reconstructed perpendicular to the center flow lumen of each renal artery at 1.2 and 2.4 cm from the renal ostium. Center of mass displacement was determined per cardiac cycle for pre- and post-EVAR renal arteries and compared.

RESULTS

Normal renal artery motion in AAA patients was impressive, with up to 3-mm movement both near and distant from the aorta (mean 2.0+/-0.6 mm, range 1.1-3.0). EVAR inhibited proximal renal motion, resulting in a 31% decrease in maximal movement (mean 1.4+/-0.7 mm, range 0.7-2.0; p < or = 0.05). Distal renal artery motion was unaffected by EVAR, with motion similar to the pre-EVAR state.

CONCLUSION

ECG-gated dynamic CTA is feasible on a 64-slice scanner with a standard radiation dose and can detect potentially serious consequences of EVAR. EVAR alters renal artery motion by limiting proximal motion while leaving distal motion unaffected.

Transrenal Fixation of Aortic Stent-Grafts: Short- to Midterm Effects on Renal Function—A Systematic Review

PURPOSE

To perform a systematic review of the short- to midterm effects of transrenal fixation of aortic stent-grafts on renal function in patients with abdominal aortic aneurysms.

MATERIALS AND METHODS

A search of the PubMed, MEDLINE, and EMBASE databases for English-language literature was performed. Studies with at least 10 patients were included for data analysis. Only studies on transrenal fixation of aortic stent-grafts that included follow-up results for renal function were included. A log-linear model was used for meta-analysis to compare transrenal fixation with infrarenal fixation.

RESULTS

Twenty-two studies met the inclusion criteria. Because two studies analyzed the same group of patients, one was excluded, for a total of 21 studies. Comparisons between transrenal fixation and infrarenal fixation were found in seven studies. For transrenal versus infrarenal fixation, the combined odds ratio, 95% confidence interval, and P value were found to be statistically significant with respect to postprocedural renal infarction only (combined odds ratio, 5.189; 95% confidence interval: 3.198, 8.420; P < .001). No significant difference was found between transrenal and infrarenal fixation with respect to renal dysfunction, renal artery occlusion, or endoleaks (P > .05).

CONCLUSION

Transrenal fixation of aortic stent-grafts seems to be a relatively safe alternative compared with infrarenal fixation in terms of short- to midterm follow-up. Postprocedural renal infarction, however, was significantly higher for transrenal fixation.

Three-dimensional visualization of suprarenal aortic stent-grafts: evaluation of migration in midterm follow-up

PURPOSE

To investigate the midterm results of transrenal fixation of abdominal aortic stent-grafts with regard to device migration and encroachment of stent wires on the renal and visceral branches.

METHODS

Imaging data from 18 patients (15 men; mean age 75 years, range 63-84) undergoing transrenal stent-graft fixation for abdominal aortic aneurysm (AAA) were included in the study. Computed tomographic angiographic data acquired within 1 week of stent-graft implantation were compared to the latest follow-up images. Postprocessing methods generated 3-dimensional (3D) maximum intensity projections (MIP) and virtual intravascular endoscopy (VIE) for evaluation of the relationship between suprarenal stents and aortic branches. Aortic neck angulation was measured in each patient for correlation with the incidence of stent migration.

RESULTS

The mean follow-up period was 40 months. 3D image visualizations showed that the stent-graft moved caudally in all patients (range 2.6-14.2 mm), with migration (>10 mm) observed in 4 (22%) patients. Corresponding VIE images documented changes in stent wire encroachment on the aortic branch ostia in 11 patients, including the number and position of crossing stent wires. There was no close relationship between aortic neck angulation and stent migration.

CONCLUSION

The current study demonstrated that migration occurs at midterm follow-up in transrenally deployed stent-grafts. 3D images were valuable for the assessment of stent migration, as well as its relationship with aortic branch ostia. Long-term follow-up of transrenal fixation deserves to be investigated, especially after observing stent migration relative to aortic ostial encroachment.

Single Center Experience with a New Commercially Available Thoracic Endovascular Graft

PURPOSE

To evaluate the intra-operative performance and clinical outcome of a new commercially available stent-graft for the treatment of thoracic aortic diseases.

METHODS AND PATIENTS

From January 2003 to October 2004, 45 consecutive patients received endovascular treatment with the Zenith TX1 device for diseases of the thoracic aorta at a single center in northern Italy. Indications included disease of the descending thoracic aorta in 26 cases, of the aortic arch in 17 cases and of the thoraco-abdominal aorta in two cases. We treated 38 atherosclerotic aneurysms, two post-traumatic aortic ruptures, two penetrating ulcers, two chronic dissections and one case was treated for aortic bleeding after voluntary acid ingestion for attempted suicide. General anesthesia was used in 20 cases. Combined or hybrid endovascular and open surgical repair was performed in 11 patients. Mean follow-up was 7 months (range 1-22 months).

RESULTS

Technical success was obtained in 44 patients (98%). One primary type I endoleak occurred (2%). ICU was used in 12 cases with a mean stay of 1 day. The mean hospital stay was 6 days (range 4-13 days). There were no hospital deaths or strokes but one transient paraplegia (2%). A type II endoleak was observed in one case and resolved spontaneously 1 month later. No aneurysm enlargement, endograft migration or structural failures were observed during follow-up. Two late unrelated-deaths were observed.

CONCLUSIONS

This stent-graft does not fulfill all the characteristics of the ideal graft, however, it proved to be safe and allowed satisfactory short term results in this group of patients treated at a single center.

Transrenal fixation of aortic stent-grafts: current status and future directions

Aortic stent-graft repair has been widely used in clinical practice for more than a decade, achieving satisfactory results compared to open surgical techniques. Transrenal fixation of stent-grafts is designed to obtain secure fixation of the proximal end of the stent-graft to avoid graft migration and to prevent type I endoleak. Unlike infrarenal deployment of stent-grafts, transrenal fixation takes advantage of the relative stability of the suprarenal aorta as a landing zone for the uncovered struts of the proximal stent. These transostial wires have sparked concern about the patency of the renal arteries, interference with renal blood flow, and effects on renal function. Although short to midterm results with suprarenal stent-grafts have not shown significant changes in renal function, long-term effects of this technique are still not fully understood. This review will explore the current status of transrenal fixation of aortic stent-grafts, potential risks of stent struts relative to the renal ostium, alternative methods to preserve blood flow to the renal arteries, and future directions or developments in stent-graft design to prevent myointimal proliferation around the stent struts.

Effect of Suprarenal Stent Struts on the Renal Artery with Ostial Calcification Observed on CT Virtual Intravascular Endoscopy

OBJECTIVES

The behaviour of stent struts crossing the renal ostia and their effect on renal ostia configuration is not well understood. The study aims to investigate whether suprarenal stent struts affect the morphological change of the renal artery with ostial calcification observed on CT virtual intravascular endoscopy.

METHODS

Nine patients with abdominal aortic aneurysms undergoing suprarenal fixation of stent grafts were included in the study. All patients received a Zenith endovascular graft with uncovered suprarenal components placed above the renal arteries. Renal ostial calcification and configuration of stent wires crossing the renal ostium were characterized in each patient and maximal transverse and longitudinal diameters of the renal ostia were measured on virtual endoscopy pre- and post-stent grafting.

RESULTS

There were altogether 17 renal ostia assessed with one patient having atrophic left kidney and no renal ostium being observed. Ostial calcification was found in five of the left renal ostia and five of the right renal ostia with one patient having bilateral ostial calcification. There was no significant difference between the renal ostial diameters measured pre- and post-stent grafting (p>0.05). Suprarenal stent struts were found to cross the renal ostia in various configurations observed on virtual endoscopy. All of the renal arteries were patent on follow-up CT scans after suprarenal fixation without stenosis or occlusion being observed. One patient with atrophic left renal artery developed renal failure following suprarenal stent grafting and received renal dialysis, while in the remaining cases median serum creatinine level did not change significantly.

CONCLUSIONS

Suprarenal stent struts did not significantly affect the renal ostia with ostial calcification in terms of the diameter measurements and renal function. Further studies deserve to investigate the long-term effect of stent struts on the renal artery in terms of cross-sectional area reduction caused by stent wires and ostial calcification.

Multislice CT Virtual Intravascular Endoscopy for Abdominal Aortic Aneurysm Stent Grafts

PURPOSE

To investigate the optimal scanning protocols of multislice computed tomographic (CT) angiography in aortic stent graft placement observed on virtual intravascular endoscopy (VIE).

MATERIALS AND METHODS

A human aorta phantom was built with a commercial aortic stent graft placed in situ. The phantom was housed in a perspex container and filled with contrast medium with CT attenuation similar to that used in the patient's abdominal scanning. CT was performed with a four-slice multislice CT scanner with section thickness of 1.3 mm, 2 mm, and 3.2 mm, pitch of 0.75, 1, and 1.5, and reconstruction interval of 50% overlap and no overlap. Stair-step artifacts were quantified by measuring the SD of signal intensity on surfaced shaded VIE images in three different locations: superior mesenteric artery (SMA), renal ostium, and aortic aneurysm.

RESULTS

Image quality of VIE images was independent of section thickness and pitch values in the level of renal ostium and aortic aneurysm (P >.05), whereas it was determined by the section thickness and pitch in the level of SMA (P <.05). Aortic branch origin became irregular or distorted when section thickness increased to 3.2 mm or pitch reached 1.5.

CONCLUSION

A scanning protocol of section thickness of 2 mm, pitch 1, and reconstruction interval of 1 mm is recommended in aortic stent graft placement because it allows fewer stair-step artifacts and better visualization of the aortic stent wires observed on VIE.

Cross-sectional area reduction of the aortic ostium by suprarenal stent wires: in vitro phantom study by CT virtual angioscopy

The study aims to investigate the reduction of cross-sectional area of the aortic ostium by the presence of aortic stent wires observed using CT virtual angioscopy in an aorta phantom. A human aorta phantom was built with a commercial stent graft placed in situ to simulate a repaired aortic aneurysm. Virtual angioscopic images of the aortic ostium and stent wires were generated in the locations of renal arteries, superior mesenteric artery and corresponding cross-sectional area reduction caused by stent wires was measured by virtual angioscopy in various scanning parameters. Our study showed that cross-sectional area reduction of the aortic ostium was determined by the diameter of renal ostium and stent wires, as well as the number of stent wires crossing the aortic ostium.

Analysis of renal function after aneurysm repair with a device using suprarenal fixation (zenith AAA endovascular graft) in contrast to open surgical repair

PURPOSE

This study was undertaken to assess the effect on renal function of open surgery and endovascular abdominal aortic aneurysm (AAA) repair with suprarenal fixation with the Zenith device.

METHODS

Data for 279 patients with similar preoperative comorbid conditions were prospectively analyzed after AAA repair. One hundred ninety-nine patients underwent endografting with the Zenith AAA Endovascular Graft, which incorporates suprarenal fixation (Zenith standard risk group, ZSR), and 80 patients underwent open surgery (standard surgical risk group, SSR). Endovascular repair was also performed in 100 patients considered poor candidates for open repair (Zenith high risk group, ZHR). Serum creatinine concentration (SCr) and anatomic defects were assessed before the procedure, before discharge, and at 1, 6, 12, and 24 months in all patients who underwent endovascular repair, and before the procedure and at 1 and 12 months in patients who underwent open surgical repair (only SCr was measured before discharge). Renal function was also analyzed, with a creatinine clearance calculation (Cockcraft-Gault). Renal insufficiency was defined as an increase in SCr greater than 30% from a preoperative baseline value, any SCr concentration in excess of 2.0 mg/dL, or any need for dialysis. Cumulative renal infarction and arterial occlusion rates were calculated with computed tomographic, ultrasonographic, and angiographic data, and reported as cumulative values.

RESULTS

Despite the initially superior renal function in the ZSR group at the pre-discharge evaluation (P =.01), there were no differences at 12 months with respect to rise in SCr greater than 30% (ZSR, 16%, vs SSR, 12%; P =.67), SCr rise greater than 2.0 mg/dL (ZSR, 2.5%, vs SSR, 3.4%; P =.66), incidence of renal artery occlusion (ZSR, 1%, vs SSR, 1.4%; P >.99), or infarction (ZSR, 1.5%, vs SSR, 1.4%; P >.99). Only one patient in each group required hemodialysis. Of note, both groups of patients demonstrated a reduction in creatinine clearance over 12 months, which then stabilized or improved by 24 months for ZSR patients.

CONCLUSIONS

Renal dysfunction occurs in a subset of patients regardless of type of repair (open or endovascular with suprarenal fixation). The cause of renal dysfunction after open or endovascular repair with a suprarenal stent is probably multifactorial. The observed dysfunction occurs in a small number of patients, and the effect in the endovascular group (no data for the surgical group at 24 months) appears to be transient. The initial dysfunction, apparent in both groups over 12 months of follow-up, stabilizes or improves at 12 to 24 months.

Diagnostic value of CT virtual intravascular endoscopy in aortic stent-grafting

PURPOSE

To investigate the diagnostic value of postprocessing techniques for 3-dimensional (3D) computed tomography (CT), with emphasis on CT virtual intravascular endoscopy (VIE), in patients with abdominal aortic aneurysms (AAA) treated with suprarenal stent-grafts.

METHODS

The preprocedural and postprocedural CT datasets from 47 AAA patients (40 men; mean age 75 years, range 61-87) undergoing aortic stent-grafting with suprarenal fixation were examined. The CT datasets were processed to create various 3D reconstructions: shaded surface display (SSD), maximum intensity projection (MIP), and VIE. Three independent radiologists assessed various diagnostic parameters for each 3D reconstruction method and compared them to axial CT images.

RESULTS

Scores for VIE reconstructions were inferior to axial CT images in the visualization of normal arterial branches, measurement of the aneurysm diameter and neck length, as well as assessment of vessel patency and presence of endoleaks. VIE was rated superior to axial CT and other 3D imaging methods in visualizing the configuration of stent struts relative to the aortic branch ostia and the number of stent wires crossing the ostia in >80% of cases.

CONCLUSIONS

VIE was not found to play a role in most preoperative situations compared to axial CT images. However, VIE provided additional postgrafting information on the 3D relationship of the suprarenal stent struts to the aortic branch ostia (in particular the renal and superior mesenteric arteries). VIE findings might aid clinicians in accurately assessing the effect of suprarenal stent-grafting on the renal arteries.

The Zenith AAA endovascular graft for abdominal aortic aneurysms: clinical update

PURPOSE

The aim of this study was to provide an update regarding the US clinical trial assessing the performance of the Zenith AAA Endovascular Graft in the treatment of abdominal aortic aneurysms.

MATERIALS AND METHODS

A prospective, nonrandomized, concurrent control-based study design was used to contrast conventional repair of infrarenal aneurysms with endovascular repair in patients that would otherwise be candidates for open surgical procedures. Additional study arms allow high-physiologic-risk patients and roll-in patients to be treated using the same endovascular device in a registry format. Patients were evaluated clinically and radiographically computed tomography (CT) and abdominal radiographs) before any intervention, at hospital discharge, 30 days, 6 months, 12 months, and yearly thereafter. Data were analyzed with the intent of assessing acute and chronic morbidity and mortality, radiographic parameters indicative of successful aneurysm repair, and device integrity.

RESULTS

A total of 352 patients were treated with the Zenith graft (one patient did not receive an implant in the standard-risk group), and 80 patients underwent conventional surgical repair. Two hundred patients were enrolled in the standard-risk group, 100 in the high-risk group, and 52 underwent endovascular repair as roll-in patients. All cause mortality, aneurysm-related deaths, and ruptures were statistically identical between the groups. Procedural morbidity was significantly lower for patients treated with endovascular grafts with respect to cardiac, pulmonary, renal, and vascular complications. Secondary interventions were more commonly required in the endovascular group. The endoleak rate was 4.9% at 12 months in the standard-risk endovascular group. There was one rupture in the high-risk subset of patients and 3 elective conversions. A total of 1.6% of the endovascular patients were noted to have a barb separation without evidence of significant migration or clinical events. No other device integrity issues were observed.

CONCLUSIONS

The safety of the Zenith endovascular graft was superior to conventional management with respect to morbidity and clinical utility. The short-term device efficacy was satisfactory; however, longer-term follow-up will be necessary to establish the duration of this observation.

Transrenal versus infrarenal endograft fixation: influence on type I endoleaks

The purpose of this study was to compare the rate of proximal type I endoleaks in patients undergoing endoluminal repair of infrarenal abdominal aortic aneurysms with endografts having either transrenal or infrarenal fixation. From September 1998 to May 2000, 42 patients received endoluminal aortic grafts for the treatment of infrarenal abdominal aortic aneurysms. Patients received either transrenal or infrarenal devices, based on the surgeon's preference. All patients had infrarenal aortic neck lengths measuring at least 1.5 cm and proximal neck angulation of <60 degrees. The endoluminal grafts were oversized by 10-20% relative to the diameter of the infrarenal aorta. The presence of endoleaks was determined at the initial procedure by contrast angiography and during subsequent follow-up at 1 month and 3 months by CT scan or duplex ultrasound. No significant differences in the rate of proximal type I endoleaks can be demonstrated between transrenal and infrarenal device types in this small cohort. Proper patient selection is more important than type of proximal fixation in preventing endoleaks.

Endovascular repair of thoracic aortic aneurysms: stent-graft fixation across the aortic arch vessels

The close proximity of the arch vessels to the origin of many thoracic aortic aneurysms (TAA) may result in placement of the stent struts across the left subclavian or carotid ostia. The purpose of this study is to determine the incidence and impact of transaortic arch vessel fixation during thoracic aortic stent graft deployment for the treatment of descending TAA. From May 1997 to July 2000, 20 patients (10 men, 10 women, mean age 82 years) with descending TAA were treated in the operating room with endoluminally placed stent grafts secured proximally to the thoracic aorta with a long (15-mm) uncovered stent segment (Talent LPS). Pre- and post-operative angiograms and IV contrast-enhanced spiral CT scans were performed in all cases. Follow-up contrast CT scans were obtained at 1, 3, 6, and 12 months and yearly thereafter to assess the adequacy of repair and to determine stent position and arch vessel patency. We found that thoracic aortic endograft fixation across the left aortic arch vessels occurs frequently during device placement and is associated with no early morbidity. Long-term follow-up is necessary to ensure that there are no late sequelae.

Endovascular repair of abdominal aortic aneurysms: stent-graft fixation across the visceral arteries

PURPOSE

Recent studies have suggested that transrenal artery fixation of endovascular stent-grafts is safe and may be a desirable means of reducing the risk of type I endoleaks, particularly those with short infrarenal necks. The close proximity of the superior mesenteric and celiac arteries to the renal arteries may commonly result in the placement of the stent struts across all the vessels of the visceral segment of the aorta. The purpose of this study was to determine the incidence and impact of transvisceral artery fixation during aortic stent-graft deployment for the treatment of abdominal aortic aneurysms (AAAs).

METHODS

From January 1997 to June 1999, 192 patients (165 men, 27 women; mean age, 82 years) with AAAs were treated with an endovascular graft secured proximally to the aorta with a long (15 mm) uncovered stent segment (60 Parodi/Palmaz, 132 Talent-LPS). Preoperative and postoperative abdominal aortograms and intravenous contrast enhanced spiral computed tomography (CT) scans were performed. Follow-up CT scans were obtained at 3, 6, and 12 months and yearly thereafter as a means of determining stent position and visceral artery patency

RESULTS

In 95 patients (49%), the uncovered stent was at or above the level of the superior mesenteric artery. In 23 patients (12%), the stent extended to the level of the celiac axis. In a mean follow-up period of 25 months (range, 6-44 months), serum creatinine levels remained stable, no stenoses or occlusions occurred in the celiac, superior mesenteric, or renal arteries, and no evidence of renal, hepatic, splenic, or intestinal infarction was present on contrast enhanced spiral CT scans. There were no type I endoleaks.

CONCLUSION

Transvisceral fixation of the uncovered proximal aortic stent occurs frequently during deployment of devices designed for transrenal fixation and is associated with no early morbidity. Long-term follow-up is necessary to ensure that there are no late sequelae.

Intrarenal color duplex examination of aortic endograft patients with suprarenal stents

PURPOSE

To report an experience using intrarenal color duplex ultrasonography (ICDU) to detect high-grade renal artery stenosis in patients who had endovascular repair of abdominal aortic aneurysm (AAA) with suprarenal stent fixation.

METHODS

Twenty-eight patients (25 men; mean age 71 years, range 58-83) who had endovascular AAA repair with suprarenal stenting at least 3 months prior to commencement of this study were screened with ICDU. Acceleration time (AT), peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) were measured. The Doppler waveform was quantitatively scored on a scale from 0 to 4. AT >0.07 seconds, RI <0.45, or a Doppler waveform score of 0 or 1 (indicating loss of early systolic peak) were indicative of high-grade renal artery stenosis.

RESULTS

Median follow-up was 15.5 months (range 3-34). ICDU was successful in 54 (98%) of 55 kidneys scanned. No AT values exceeded 0.07 seconds, all RIs were >0.45, and no waveforms had loss of early systolic peak, indicating that no patient had evidence of high-grade renal artery stenosis.

CONCLUSIONS

ICDU is a simple and affordable method that seems well suited to periodic screening in patients with suprarenal stents. Longer follow-up with a larger number of patients is needed before definite conclusions can be drawn about the effect of suprarenal stenting on renal circulation.

Treatment of Stanford type B aortic dissection with stent-grafts: preliminary results

PURPOSE

To evaluate the feasibility and safety of endovascular stent-graft placement in treating Stanford type B aortic dissection.

MATERIALS AND METHODS

Seven patients underwent endovascular stent-graft placement for type B aortic dissection. Five patients had acute and two had chronic dissection. In five patients, the proximal entry tear was within 2 cm of the origin of the left subclavian artery, and in two patients it was beyond this site. In three patients, the noncovered proximal portion of the stent-graft was placed across the origin of the left subclavian artery. The efficacy of the procedure was assessed at follow-up studies 3, 6, 12, and 24 months after intervention.

RESULTS

The procedure was technically and clinically successful in six patients (86%). The left subclavian artery remained patent in all patients. In two patients with involvement of aortic branches, endovascular stent-graft placement restored adequate blood flow to the compromised branches. One patient was readmitted 1 month later because the dissection extended into the ascending aorta. In all but this patient, closure of the entry tear and thrombosis of the false lumen along the stent-graft were achieved. All false lumina shrank considerably. The mean follow-up time was 14 months (range, 1-25 months).

CONCLUSION

Type B aortic dissections within and beyond 2 cm of the origin of the left subclavian artery can be treated safely and effectively by means of endovascular stent-graft placement.

Transrenal fixation of aortic endografts: intermediate follow-up of a single-center experience

PURPOSE

To examine the fate of the renal ostia following transrenal fixation of endovascular aortic stent-grafts.

METHODS

Thirty-five patients (29 men; mean age 75 years) undergoing endovascular repair for abdominal aortic aneurysms (AAAs) had transrenal fixation of the uncovered proximal stent due to a short (< 1.5 cm long) or conical neck or a periprocedural endoleak. Eighteen (51%) patients were hypertensive; 7 (20%) had renal artery stenoses (RAS). Outcome measures included blood pressure, serum creatinine, computed tomography, and renal artery duplex scans.

RESULTS

Two patients with > or = 60% RAS had renal stents placed during the endograft procedure; the other 5 RAS patients were normotensive and their renal lesions were not treated. Overall technical success was 82.9% (29/35). One (2.9%) case was converted due to graft twisting. There were 5 (14.2%) early endoleaks. Transient postoperative creatinine elevations were observed in 5 (14.2%) cases. Over a median 11-month period (range 2-24), no secondary endoleaks or silent renal artery occlusions were seen. One normotensive patient with an untreated > or = 60% renal lesion developed hypertension and severe stenosis (99%) at 4 months; stenting through the interstices of the transrenal stent was performed. No disease progression was seen in the other 6 RAS patients.

CONCLUSIONS

In the intermediate period, transrenal fixation appears to have no adverse effects on renal blood flow. Moreover, in patients with no evidence of renal disease or preoperative RAS < 60%, it does not precipitate or cause progression of renal stenosis. However, patients with preoperatively documented RAS > or = 60% are a concern and mandate further study.

Endovascular Treatment of Aortic Disease

A review is given of endovascular treatment for AAA, thoracic aortic aneurysms, dissections as well as complications following previous aortic surgery. In several of these conditions endovascular treatment has advantages like a reduced operative trauma, shorter stay in hospital, and the possibility of treating patients who would have been unfit for open surgery. On the other hand, problems like endoleak, deformation of the endoprosthesis, retrograde filling of the aneurysmal sack, and graft limb occlusion need to be solved before the place of endovascular treatment can be defined. It is possible that the steadily improving quality of the implants as well as the introducer systems will widen the indications for endovascular surgery, but randomised clinical trials are warranted and a longer follow-up period is necessary to draw final conclusions.

Endovascular repair of descending thoracic aortic aneurysms: an early experience with intermediate-term follow-up

PURPOSE

The purpose of this study was to report an initial experience with the endovascular repair of descending thoracic aortic aneurysm. Complications and intermediate-term morphologic changes were identified with the intent of altering patient selection and device design.

METHODS

Endografts were placed into 25 patients at high-risk for conventional surgical repair over a 3(1/2)-year period. Devices were customized on the basis of preoperative imaging information. Follow-up computed tomography scans were obtained at 1, 3, 6, and 12 months and yearly thereafter. Additional interventions occurred in the setting of endoleaks, migration, and aneurysm growth.

RESULTS

The overall 30-day mortality rate was 20% (12.5% for elective cases; 33% for emergent cases). There were 3 conversions to open repair. Neurologic deficits developed in 3 patients; 1 insult resulted in permanent paraplegia. Neurologic deficits were associated with longer endografts (P =.019). Three endoleaks required treatment, and 1 fatal rupture of the thoracic aneurysm treated occurred 6 months after the initial repair. Migrations were detected in 4 patients. The maximal aneurysm size decreased yearly by 9.15% (P =.01) or by 13.5% (P =.0005) if patients with endoleaks (n = 3 patients) were excluded. Both the proximal and distal neck dilated slightly over the course of follow-up (P =.019 and P =.001, respectively). The length of the proximal neck was a significant predictor of the risk for endoleakage (P =.02).

CONCLUSION

The treatment of descending thoracic aortic aneurysms with an endovascular approach is feasible and may, in some patients, offer the best means of therapy. Early complications were primarily related to device design and patient selection. All aneurysms without endoleaks decreased in size after treatment. Late complications were associated with changing aneurysm morphologic features and device migration. The morphologic changes remain somewhat unpredictable; however, alterations in device design may result in improved fixation and more durable aneurysm exclusion.

Endovascular repair of abdominal aortic aneurysm using a pararenal fenestrated stent-graft

PURPOSE

To report an unusual case of endovascular abdominal aortic aneurysm (AAA) exclusion in which a fenestrated stent-graft was used to seal a proximal Type I endoleak.

METHODS AND RESULTS

An 84-year-old man with a 6.0-cm AAA underwent an aortomonoiliac aneurysm exclusion procedure that was complicated by a proximal endoleak. Because the patient had no right kidney, an additional stent-graft was designed to cover the right renal artery stump while preserving left renal perfusion through a fenestration in the graft material. This approach was successful in obliterating the endoleak around the proximal attachment site, but flow through the lumbar arteries remained.

CONCLUSIONS

The use of a fenestrated stent-graft is feasible, but the type of fenestration in this case has limited applicability owing to the rarity of patients with suitable anatomy.

Complications in the endovascular repair of abdominal aortic aneurysms: a risk factor analysis

OBJECTIVES

to identify risk factors for complications following endovascular repair of abdominal aortic aneurysms (AAAs).

MATERIALS AND METHODS

endovascular AAA exclusion was attempted in 64 patients. Patient characteristics, anatomic features of the aneurysm, operative technical aspects, and the experience of the teams were correlated with mortality, occurrence of endoleak, and other complications. Perioperative complications were graded following the recommendations of the Ad Hoc Committee on reporting standards. For the assessment of correlation between risk factors and outcomes a logistic regression analysis was used.

RESULTS

complications were observed in 43% of the procedures and were classified as mild (24%), moderate (55%) or severe (21%). American Society of Anaesthesiology (ASA) risk class 3 or 4, and advanced age were independent risk factors for perioperative death and complications. Adjuvant procedures or overstenting of the renal arteries with the uncovered part of the stent were not associated with increased risk of complications. Nevertheless, in four of 24 overstented renal orifices, a renal infarction or ischaemia of the kidney was observed on a postoperative CT scan. Advanced experience was associated with less complications, less endoleaks, and shorter operating time.

CONCLUSIONS

high age and medical co-morbidity were associated with increased risk for perioperative complications and death. Additional perioperative procedures are usually well tolerated. With greater experience in endovascular AAA grafting the incidence of complications and endoleaks decreased.

Endovascular repair of abdominal aortic aneurysm using the EVT device: limited increased utilization with availability of a bifurcated graft

PURPOSE

To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed.

RESULTS

Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous.

CONCLUSIONS

Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

Endovascular AAA exclusion: will stents with hooks and barbs prevent stent-graft migration?

PURPOSE

To investigate if stents with hooks and barbs will improve stent-graft fixation in the abdominal aorta.

METHODS

Sixteen- to 24-mm-diameter Dacron grafts were deployed inside cadaveric aortas. The grafts were anchored by stents as in endovascular abdominal aortic aneurysm repair. One hundred thirty-seven stent-graft deployments were carried out with modified self-expanding Z-stents with (A) no hooks and barbs (n = 75), (B) 4 5-mm-long hooks and barbs (n = 39), (C) 8 10-mm-long, strengthened hooks and barbs (n = 19), or (D) hooks only (n = 4). Increasing longitudinal traction was applied to determine the displacement force needed to extract the stent-grafts. The radial force of the stents was measured and correlated to the displacement force.

RESULTS

The median (interquartile range) displacement force needed to extract grafts anchored by stent A was 2.5 N (2.0 to 3.4), stent B 7.8 N (7.4 to 10.8), and stent C 22.5 N (17.1 to 27.9), p < 0.001. Both hooks and barbs added anchoring strength. During traction, the weaker barbs were distorted or caused intimal tears. The stronger barbs engaged the entire aortic wall. The radial force of the stents had no impact on fixation, while aortic calcification and graft oversizing had marginal effects.

CONCLUSIONS

Stent barbs and hooks increased the fixation of stent-grafts tenfold, while the radial force of stents had no impact. These data may prove important in future endograft development to prevent stent-graft migration after aneurysm exclusion.

Impact of transrenal aortic endograft placement on endovascular graft repair of abdominal aortic aneurysms

PURPOSE

Successful endovascular repair of an abdominal aortic aneurysm (AAA) requires the creation of a hemostatic seal between the endograft and the underlying aortic wall. A short infrarenal aortic neck may be responsible for incomplete aneurysm exclusion and procedural failure. Sixteen patients who had an endograft positioned completely below the lowest renal artery and 37 patients in whom a porous portion of an endograft attachment system was deliberately placed across the renal arteries were studied to identify if endograft positioning could impact on the occurrence of incomplete aneurysm exclusion.

METHODS

Fifty-three patients underwent aortic grafting constructed from a Palmaz balloon expandable stent and an expandable polytetrafluoroethylene (ePTFE) graft implanted in an aorto-ilio-femoral, femoral-femoral configuration. Arteriography, duplex ultrasonography and spiral CT scans were performed in each patient before and after endografting to evaluate for technical success, the presence of endoleaks, and renal artery perfusion.

RESULTS

There was no statistically significant difference in patient demography, AAA size, or aortic neck length or diameter between patients who had their endografts placed below or across the renal arteries. However, significantly more proximal aortic endoleaks occurred in those patients with infrarenal endografts (P < or = .05). Median serum creatinine level before and after endografting was not significantly different between the 2 patient subgroups, with the exception of 2 patients who had inadvertent coverage of a single renal orifice by the endograft. Median blood pressure and the requirement for antihypertensive therapy remained the same after transrenal aortic stent grafting. Significant renal artery compromise did not occur after appropriately positioned transrenal stents as shown by means of angiography, CT scanning, and duplex ultrasound scan. Mean follow-up time was 10.3 months (range, 3 to 18 months). Patients who had significant renal artery stenosis (> or =50%) before aortic endografting did not show progression of renal artery stenosis after trans-renal endografting. Two patients with transrenal aortic stent grafts had inadvertent coverage of 1 renal artery by the endograft because of device malpositioning, which resulted in nondialysis dependent renal insufficiency. In addition, evidence of segmental renal artery infarction (<20% of the kidney), which did not result in an apparent change in renal function, was shown by means of follow-up CT scans in 2 patients with transrenal endografts.

CONCLUSION

Transrenal aortic endograft fixation using a balloon expandable device in patients with AAAs can result in a significant reduction in the risk of proximal endoleaks. Absolute attention to precise device positioning, coupled with the use of detailed imaging techniques, should reduce the risk of inadvertent renal artery occlusion from malpositioning. Long-term follow-up is essential to determine if there will be late sequelae of transrenal fixation of endografts, which could adversely effect renal perfusion.

Endovascular repair of aortic aneurysms in the the presence of a horseshoe kidney

PURPOSE

To report two cases of endovascular aortic aneurysm exclusion in patients with a horseshoe kidney.

METHODS AND RESULTS

Two male patients, one with a known horseshoe kidney and history of multiple previous laparotomies, presented with abdominal aortic aneurysms of approximately 6-cm diameter. Each was treated with a tapered aortomonoiliac polytetrafluoroethylene graft secured proximally with a Palmaz balloon-expandable stent. The endograft was sutured distally to a Dacron femorofemoral crossover graft. An anomalous renal vessel was sacrificed in one case. The aneurysms were successfully excluded, and the patients recovered without sequelae.

CONCLUSIONS

Endovascular repair should be considered as a treatment option in patients with aortic aneurysm in the presence of a horseshoe kidney, particularly if the renal vasculature can be wholly preserved.

Abdominal aortic aneurysm treatment: preliminary results with the Talent stent-graft system

PURPOSE

To evaluate the treatment of abdominal aortic aneurysm (AAA) with use of the endoluminal Talent stent-graft (TSG).

PATIENTS AND METHODS

In 10 men, AAA treatment was attempted with use of the TSG. All patients presented significant surgical risk, with chronic obstructive pulmonary disease and coronary arteriopathy. The mean age was 65.5 years (range, 57-82 years). The mean proximal neck diameter was 25.8 mm (range, 21.6-34 mm). Five of the TSGs were straight tubes and five were bifurcated systems. The main body of the TSG is made of a polyester graft material mounted on a self-expandable nitinol frame. The bifurcated system uses polytetrafluoroethylene (PTFE) material for the legs and extensions mounted on a self-expandable nitinol frame. The bifurcated grafts used a 22 to 27-F introducer and the extensions, a 18-F introducer through a surgical cutdown technique.

RESULTS

The TSG system was successfully implanted in nine patients and failed in one because of dislodgment after deployment, which required conversion to surgery. Four leaks occurred initially. One was sealed off with balloon dilation at the end of the procedure, one leak was treated with an additional extension, another leak disappeared spontaneously in 30 days, and the other leak required embolization 4 weeks after discharge. Seven patients were discharged on the third day after the procedure, and two patients were discharged at 1 and 2 weeks, respectively. Blood transfusion was necessary in three patients because of hematoma at the incision site in two patients, which required surgical revision for hemostasis, and because of transoperative bleeding in one patient. Follow-up time ranged from 2 to 15 months. The only death occurred 5 days postoperatively as a consequence of ischemic colitis and multisystem organ failure in the only patient who required surgery.

CONCLUSION

Treatment of AAA with the TSG system is effective for aneurysm exclusion. This device seems to provide a good alternative to surgery in patients who are otherwise considered to be at high risk for complications after direct surgical repair, but it is not without risk of complications.

Endograft repair of an aortic pseudoaneurysm following gunshot wound injury: impact of imaging on diagnosis and planning of intervention

PURPOSE

To describe the endovascular treatment of a gunshot injury to the visceral aorta and the role of various imaging modalities in the staging and planning of the endograft procedure.

METHODS AND RESULTS

The bullet entered the aorta posteriorly beneath the origin of the superior mesenteric artery and traversed the wall in a tangential manner entering the lumen proximal to the renal arteries. Intravascular ultrasound (IVUS) imaging and spiral computed tomography (CT) identified the injury that the initial angiograms failed to demonstrate. Combined use of IVUS and CT imaging enabled observation of the evolution of a pseudoaneurysm until an interval when endograft exclusion was possible. A stent-graft was customized based on precise IVUS and CT dimensional data and implanted successfully through an arteriotomy in the common femoral artery 3 weeks after the initial injury. Three-month follow-up imaging demonstrated continued exclusion of the pseudoaneurysm, and the patient remains well at 16 months.

CONCLUSIONS

IVUS and spiral CT scans were instrumental in identifying an arteriographically undetected aortic injury. The combined imaging modalities also helped determine the timing for the endovascular procedure and provided the precise measurements for device fabrication and deployment.

Renal arteries covered by aortic stents: clinical experience from endovascular grafting of aortic aneurysms

OBJECTIVES

During the endovascular repair of abdominal aortic aneurysms (AAAs), effective anchoring of the stent-graft is difficult in the presence of a short infrarenal aneurysm neck. The aim of this study was to investigate renal artery patency and renal function after deployment of graft anchoring stents across the renal arteries.

DESIGN

Retrospective open study.

PATIENTS

Twenty-five renal arteries, in 18 patients treated by endovascular exclusion of an AAA, were intentionally covered with the Gianturco Z-stent to ensure stent graft attachment.

METHODS

Renal artery patency was assessed by repeated spiral computed tomography (CT) scans and angiography. Creatinine levels, blood pressure and antihypertensive medication were recorded. Follow-up was a median 6 months (2-9).

RESULTS

All 25 stent-covered renal arteries remained patent. CT showed a small infarct in one kidney. Creatinine was 108 mumol/l (89-133) before intervention and 98 mumol/l (87-127) at follow-up. Blood pressure was 150/80 mmHg on both occasions. Antihypertensive therapy was intensified in one patient whose creatinine level remained stable and whose separate renin sampling was normal.

CONCLUSIONS

Covering the renal arteries with the Gianturco Z-stent does not seem to affect renal function within 6 months. Further follow-up is needed before suprarenal stent deployment can be advocated.

The use of intravascular ultrasound as control procedure for the deployment of endovascular stented grafts

OBJECTIVE

To assess whether intravascular ultrasound (IVUS), used systematically in a series of patients with abdominal aortic aneurysms (AAA), is a feasible control procedure to ensure correct transfemoral placement of endovascular stent grafts (TPEG).

DESIGN

Descriptive study.

MATERIALS AND METHODS

Fourteen patients with infrarenal aortic aneurysms were treated by the placement of one tube graft, 10 aorto-uni-iliac and three aorto-bi-iliac grafts. Arteriography and IVUS were performed before, during and after deployment of the graft to ensure correct placement in relation to side branches, and proper adaptation of the stents to the aortic wall. Postoperative CT-scan and arteriography served as control procedures.

RESULTS

IVUS identified both renal arteries before graft deployment in eight of 13 (62%) patients. In the remaining patients only one renal artery was visualised due to interference from guidewires or the introducer system. Imaging during stent deployment was abandoned after IVUS catheter damage in two of three cases. Postprocedural IVUS was able to evaluate the expansion of the stents and the adaptation to the aortic wall in all instances. In four (29%) cases a leak was identified. Additional intervention included deployment of a further stent (n = 2) or redilation (n = 2). Covering of the renal arteries could only be indirectly determined by IVUS.

CONCLUSION

IVUS can provide important decisive information before and after stented graft deployment, with the limitations that guidewires, introducer system and stents may cause interference. Contemporary IVUS designs are unsuitable for monitoring stent deployment.

Changing aneurysmal morphology after endovascular grafting: relation to leakage or persistent perfusion

PURPOSE

To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors.

METHODS

Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12).

RESULTS

At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion.

CONCLUSIONS

The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.