Abdominal aortic aneurysms: treatment with juxtarenal placement of covered stent-grafts

Incidence of Renal Infarctions after Endovascular AAA Repair: Relationship to Infrarenal versus Suprarenal Fixation

Purpose:

To analyze the incidence and etiology of renal infarctions following endovascular abdominal aortic aneurysm (AAA) repair detected on computed tomography (CT) and determine any association with infrarenal versus suprarenal fixation.

Methods:

Between August 1994 and October 2001, 663 patients (604 men; mean age 68.5 years, range 40–98) underwent endovascular AAA repair with predominately bifurcated (505, 77%) stent-grafts. About a third (202, 30%) of the devices were deployed in a suprarenal position. Contrast-enhanced CT scans were performed on days 10, 90, and 365 after operation and then annually. Two radiologists blinded to procedural details compared the preoperative and postoperative scans to identify renal infarctions from inadvertent renal artery occlusion by the endograft. Only patients with inadvertent infarctions were analyzed relative to endograft fixation position and stent-graft type.

Results:

Mean follow-up was 37 months (range 0.1–75). Overall renal infarction rate was 11.9% (n=79); 23 (3.4%) patients suffered from limited, segmental infarction due to intentional covering of preoperatively diagnosed accessory renal arteries. Unintentional renal ischemia was identified in 56 (8.5%) patients. In this subgroup, 39 (19%) were observed in the 202 patients with suprarenal fixation versus 17 (3.7%) in the 461 stent-grafts positioned infrarenally (RR 3.35, 95% CI 2.20 to 5.04, p < 0.00001). There was a significant correlation between the incidence of infarction and the device type (14.3% for modular grafts versus 5.6% for unibody designs, p = 0.0002). Seventeen (2.6%) patients suffered from unilateral kidney loss, with dialysis required in 2 cases. Creatinine and urea showed no significant postoperative elevation in the overall patient population, but both levels were significantly (p < 0.02) elevated in patients with complete unilateral renal infarcts.

Conclusions:

Transrenal fixation of aortic endografts had a 3-fold higher risk for renal infarction in this large patient population. There is no significant difference for specific endografts, but modular designs were associated with a higher rate of renal infarction. The need to occlude preoperatively diagnosed accessory renal arteries with an endograft should be considered a contraindication for current available devices.

Suprarenal endograft fixation and medium-term renal function: systematic review and meta-analysis

BACKGROUND

Suprarenal fixation is widely used in endovascular aneurysm repair. Numerous small, underpowered studies have concluded that it does not increase the risk of renal impairment compared with infrarenal fixation. A recent meta-analysis demonstrated that renal infarction is more common with suprarenal fixation, but the effect on renal function remains unclear.

METHODS

Electronic abstract databases, article reference lists, and conference proceedings were searched for series reporting renal function data after suprarenal fixation. There was considerable study heterogeneity with respect to key factors such as pre-existing renal dysfunction and length of follow-up. Authors were contacted to obtain individual patient data for a pooled reanalysis using standardized criteria.

RESULTS

Of 46 potentially relevant citations, only 11 were eligible for inclusion in the meta-analysis. Complete data sets were available for four studies (1065 patients), with a median follow-up of 33 months. Kaplan-Meier curves were constructed for postoperative renal impairment in the suprarenal fixation and infrarenal fixation groups and compared by the log-rank test. Median time free of renal impairment was 38.5 months in the infrarenal fixation group compared with 32.4 months in the suprarenal fixation group (P = .0038). However, to account for significant methodologic differences, further analysis was required using a Weibull regression model fitted in open Bayesian inference using Gibbs sampling (BUGS). The pooled hazard ratio for deterioration of renal function after suprarenal fixation was 0.6 (95% confidence interval, 0.3-10).

CONCLUSION

Currently available data are insufficient to determine the precise effect of suprarenal fixation on medium-term renal function. Conventional Kaplan-Meier analysis of the pooled data set suggested that suprarenal fixation increased the risk of renal dysfunction; however, the effect disappeared when sophisticated statistical modelling was performed to account for study heterogeneity. A randomised controlled trial of suprarenal fixation may resolve this issue.

Systematic Review and Meta-analysis of 12 Years of Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Endovascular repair (ER) of abdominal aortic aneurysm (AAA) is a new technique, and reported rates of endoleak, conversion to open repair, rupture and mortality vary widely. The aim of this study was to estimate these rates from the published data, and examine how this has changed as more patients have undergone ER.

METHODS

A systematic review and meta-analysis of publications identified through searches of the electronic databases EMBASE and Medline. All publications quoting endoleak, conversion to open repair, rupture and mortality rates for a series of patients undergoing ER were included.

RESULTS

163 studies pertaining to 28,862 patients undergoing ER were identified as relevant for the review and meta-analysis. The pooled estimate for operative mortality was 3.3% (95% confidence interval 2.9 to 3.6%). The pooled estimate for type 1 endoleaks was 10.5% (95% confidence interval 9.0 to 12.1%), with an annual rate of 8.4% (95% confidence interval 5.7% to 12.2%). The pooled estimate of type 2,3 and 4 endoleaks was 13.7% (95% confidence interval 12.3 to 15.3%), with an annual rate of 10.2% (95% confidence interval 7.4% to 14.1%). The pooled estimate for primary conversion to open repair was 3.8% (95% confidence interval 3.2 to 4.4%), and for secondary conversion to open repair 3.4% (95% confidence interval 2.8 to 4.2%). The pooled estimate for post-operative rupture was 1.3% (95% confidence interval 1.1 to 1.7%), with an annual rupture rate of 0.6% (95% confidence interval 0.5% to 0.8%). Multivariate meta-regression analysis showed that rates of operative mortality, post-operative rupture and total number of endoleaks all fell significantly (p<0.05) over time.

CONCLUSIONS

This study demonstrates a low mortality and a gradual reduction in vascular morbidity and mortality associated with endovascular repair since it was first introduced.

Incidence of Renal Infarctions After Transrenal Stent Placement in an Animal Model

PURPOSE

To evaluate the incidence and appearance of renal infarctions after transrenal stent placement in an animal model.

METHODS

An aortic stent was placed via a femoral approach in 20 female Merino sheep. Ten animals had intentional coverage of one renal ostium with the bare struts, 1 sheep had both renal artery ostia covered, and the other 9 sheep had no stent impingement on the renal orifices. Animals were sacrificed after 3 to 12 months (mean 6) for gross pathological and histological evaluation. Infarction locations and patterns were evaluated and correlated to stent placement.

RESULTS

Of the 40 renal arteries, coverage was proven at autopsy in 12 cases; the remaining 28 arteries were free of any stent overlay. Overall, 14 (35%) renal infarctions were detected; 7 were found in the 12 arteries with a transrenal stent (58.3% incidence in covered renal arteries). By comparison, the other 7 infarctions were found in the 28 unaffected arteries (25% incidence in noncovered renal arteries; p = 0.04). All infarctions appeared to be well-defined punctate lesions.

CONCLUSIONS

A transrenal stent position in the abdominal aorta is related to increased renal infarctions in an animal model.

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.

Endovascular treatment of abdominal aortic aneurysms--6 years of experience with Ella stent-graft system

PURPOSE

Evaluation of 6-year results of abdominal aortic aneurysm (AAA) treatment by Ella stent-grafts with regard to safety and effectivity in relation to morphology of the aneurysm.

METHODS

From a group of 172 patients with AAA, in whom elective endovascular treatment was considered, 120 of them (69.8%) were found to be suitable for this type of therapy. The bifurcated type of stent-graft was implanted in 97 patients, uniiliacal type in 19 patients and only four patients were found to be suitable for tubular type of stent-graft. Additional necessary procedures (internal iliac artery occlusion or contralateral common iliac artery occlusion in a group of patients with uniiliacal type of stent-graft) were performed surgically during the stent-graft implantation. CT and US controls were performed at 3, 6 and 12 months after implantation, later every 12 months.

RESULTS

Primary technical success was achieved in 109 of the 120 patients (91%). Primary endoleak was recorded in 11 patients (primary endoleak type Ia in seven patients, type Ib in three patients and type IIIa in one patient). Assisted technical success after reintervention or spontaneous seal was 98.3%. Surgical conversion was indicated in two patients (1.7%). Perioperative mortality rate was 3.3%. Total average follow-up period was 20.7 months (range from 2 to 60 months). In nine patients (7.5%) secondary endoleak type II was found at control CT or US, in three patients partial thrombosis of the stent-graft was found. There was no aneurysm rupture during follow-up.

CONCLUSION

Treatment of AAA with Ella stent-graft system is effective and safe. Bifurcated stent-graft is the most frequently used type. Uniiliacal type of stent-graft is used by us only in cases of complicated morphology.

Treatment of Extracranial and Intracranial Aneurysms and Arteriovenous Fistulae Using Stent Grafts

OBJECTIVE:

Treatment of 11 patients with aneurysms or arteriovenous fistulae of the craniocervical arteries with stent grafts.

METHODS:

Peripheral stent grafts were deployed in two extracranial internal carotid arteries. Coronary stent grafts were used to treat two giant aneurysms, five direct carotid-cavernous fistulae, one vertebrojugular fistula, and two dissecting aneurysms of the vertebral artery (V2 and V4).

RESULTS:

Stent grafts were used successfully in two extracranial internal carotid and two extracranial vertebral arteries, one dissecting aneurysm of the intracranial vertebral artery, one giant aneurysm and one pseudoaneurysm of the cavernous internal carotid artery, and five direct carotid-cavernous sinus fistulae. Angiographic follow-up examinations (available in nine patients; obtained at 3 mo to 5 yr; average, 24 mo) revealed normal vessel caliber, and the stent grafts in all 9 of 11 initial patients were patent. There was a recurrent saccular aneurysm adjacent to the stent graft in the patient with the intracranial vertebral artery aneurysm. The following five complications were encountered: transient hemiparesis (n = 2), increased hemiparesis, post-procedural management-related fatality, and ICA dissection. In six patients, stent graft deployment was accomplished without any technical or clinical complication. There were no permanent neurological deficits consequent to stent graft placement.

CONCLUSION:

Stent grafts are a useful tool for the endovascular treatment of head and neck aneurysms and direct arteriovenous fistulae in selected patients. The major disadvantage of the currently available stent grafts is their lack of mechanical flexibility. Maneuvering stent grafts in the intracranial arteries carries the risk of iatrogenic vessel dissection and may require supportive measures and protection of the target site by conventional stents.

Suprarenal fixation of endograft in abdominal aortic aneurysm treatment: focus on renal function

OBJECTIVE

The objective of this work was to evaluate any variation of renal function detected by renal scintigraphy after the suprarenal fixation of endografts for abdominal aortic aneurysm (AAA) repair.

SUMMARY BACKGROUND DATA

In the few articles that have considered this problem, renal function was evaluated only by biochemical tests, which are inadequate in demonstrating small changes in renal function and in appreciating the worsening of a single kidney's function.

METHODS

Between April 1999 and May 2002, 47 patients with an inappropriate infrarenal proximal neck had a suprarenal fixation for AAA. To assess renal function, a technetium-99m diethylene triamine penta-acetic acid (TC-DTPA) perfusion scintigraphy was performed preoperatively on the third postoperative day and at 6, 12 months, and then yearly thereafter. Worsening of renal function was defined as a decrease of glomerular filtration rate (GFR) > or =20% (detected with Gates method). Serum creatinine level was tested preoperatively and at the first and third postoperative day.

RESULTS

Endograft deployment was technically successful in 44 patients (93.6%); clinical perioperative success was obtained in 46 patients (97.8%). In 12 patients (25.5%), a permanent reduction of the GFR was observed using postoperative TC-DTPA perfusion scintigraphy. By 99m TC-DTPA perfusion scintigraphy, a permanent reduction of GFR was observed postoperatively in 12 patients. A slight GFR reduction (<20%) was present in 7 (14.9%) patients, due to the planned occlusion of accessory renal arteries. A more significant GFR reduction (>20%) was present unexpectedly in 5 (10.6%) patients, in 3 of these a single kidney was involved, in 5 both with an increase of the serum creatinine level >20%.

CONCLUSIONS

Suprarenal fixation of endografts in AAA treatment is a safe procedure with good early and midterm procedural results and a risk of GFR impairment (>20%) of 10.6%.

Endovascular aneurysm repair with the Talent stent-graft

PURPOSE

Evaluation of the Talent endovascular aortic stent graft in the management of abdominal aortic aneurysms.

MATERIALS AND METHODS

Thirty-eight patients with suitable abdominal aortic aneurysms were treated over an 18-month period using the modular Talent stent graft. The suprarenal Talent device was deployed in 31 cases. Clinical follow-up of all patients has been performed by clinical examination, contrast-enhanced CT, and Duplex ultrasound for a mean period of 12.5 months.

RESULTS

Graft placement was successful in all 38 patients. The immediate exclusion rate was 84%, the 1-month primary exclusion rate was 92.1%, and the 3-month exclusion rate was 97%. There were no deaths in the first 30 days, one death at 3 months due to a presumed rupture, and one other death at 1 year due to carcinomatosis. There have been no migrations or renal complications in the suprarenal group.

CONCLUSIONS

Our short- and medium-term results are comparable with other published Talent stent-graft series. Suprarenal graft fixation is a safe procedure that may aid in preventing graft migration. Long-term follow-up is required to assess the durability of the suprarenal Talent device.

Totally laparoscopic juxtarenal aortic anastomosis: an experimental study

The surgical management of juxtarenal aneurysms necessitates suprarenal aortic clamping and control of the renal arteries. We attempted to reproduce this procedure laparoscopically. Five female piglets were submitted to a totally laparoscopic approach of the aortoiliac segment. After laparoscopic control of the renal arteries and suprarenal clamping, a 6-mm Dacron tube graft was anastomosed to the juxtarenal aorta. After the procedure, a midline laparotomy allowed verification of the patency of the renal arteries and the quality of the anastomosis. Mean operative time was 198 minutes (range, 170-240 minutes). The dissection took an average of 92 minutes (range, 75-110 minutes). The mean suprarenal aortic cross-clamp time was 46.3 minutes (range, 29.1-81.5 minutes), and the mean anastomotic time was 28.9 minutes (range, 16.5-68.1 minutes). This study demonstrates in this animal model the feasibility of juxtarenal aortic anastomosis using a laparoscopic technique. Newly designed instruments should allow a shorter clamping time in the future.

Abdominal aortic aneurysm and renal artery stenosis: renal function and blood pressure before and after endovascular treatment

We describe three patients with abdominal aortic aneurysm (AAA) and renal artery stenosis (RAS). These patients were treated by placement of an aortic endograft and angioplasty or stenting of the renal artery. After the procedure renal function improved or remained stable in two patients and deteriorated slightly in one. Blood pressure was reduced in one hypertensive patient and remained normal in the other two normotensive patients. In conclusion, simultaneous treatment of AAA and RAS with aortic endograft placement and renal artery angioplasty with or without stent, is a safe and effective technique for selected high-risk patients.

Thromboembolic complications after endovascular aortic aneurysm repair

PURPOSE

To evaluate the frequency and significance of thromboembolic complications following endovascular treatment of aortic aneurysms.

METHODS

One hundred seventy-four patients (153 men; mean 71.4 years, range 26-90) underwent endovascular repair of aneurysms of the thoracic (n = 38) or abdominal (n = 136) aorta using a variety of endografts. All patients were examined preprocedurally using 3-phase helical computed tomography (CT) to determine appropriate endograft size. To exclude the occurrence of infarction in parenchymal organs, the first postprocedural CT scan was compared with preoperative findings. Newly recognized perfusion deficits were taken as evidence of procedure-related infarction.

RESULTS

Infarctions were detected in 16 (9.2%) patients: 13 in the kidneys, 2 in the spleen, with 1 in the mesentery; only the mesenteric infarction was clinically symptomatic. Both splenic infarctions were associated with deployment of stent-grafts in the thoracic aorta (5.3% of the 38 patients), while the mesenteric and 13 renal infarctions were seen in patients with infrarenal abdominal aortic aneurysms (0.7% and 9.6%, respectively, of 136 patients). One patient experienced complete thromboembolic occlusion of a renal artery, which was partially recanalized with intraoperative lysis.

CONCLUSIONS

Thromboembolic complications of endovascular aortic aneurysm repairs are not uncommon, and although usually asymptomatic, these sequelae have the potential to be life threatening. Perfusion abnormalities may respond to immediate lytic therapy with complete dissolution of the thrombus in certain isolated cases.

Renal function after aortic stent-grafting including coverage of renal arterial ostia

Considerable experience has been gained with endoluminal stent-graft techniques for the treatment of infrarenal aortic aneurysms. The inclusion of uncovered suprarenal stents eases the treatment of cases with a short, angulated, or bottlenecked proximal neck. However, few data have been published on the effect of a stent-graft crossing renal artery ostia on long-term renal function. We therefore retrospectively analyzed the influence of intra-aortic stent-grafts, including suprarenal fixation on long-term renal function. Thirty-nine patients who received a Gianturco Z stent across renal artery ostia as part of a made-to-measure stent-graft treating an infrarenal aortic aneurysm were evaluated at 6 (all patients) and 30 months (15 patients) after surgery. Renal function evaluation included serum creatinine level, creatinine clearance using the Cockcroft-Gault formula, and renal tomography. Initial technical success was achieved in all patients. There were no minor or major complications. Mean serum creatinine levels were 1.16 +/- 0.25, 1.12 +/- 0.28, and 1.24 +/- 0.25 mg/dL before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = not significant [NS]). Mean creatinine clearances were 60.3 +/- 19.7, 63 +/- 23, and 60.6 +/- 17.5 mL/min before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = NS). Only two patients (5%) had a decrease in glomerular filtration rate greater than 20% at 6 months. Both patients had renal insufficiency before endovascular grafting. Renal function was stable in all patients at 30 months' follow-up. We suggest that renal function is unaffected by coverage of renal arterial ostia with Gianturco Z stents.

Renal infarction following endovascular aortic aneurysm repair: incidence and clinical consequences

PURPOSE

To investigate the incidence of renal infarction following endovascular abdominal aortic aneurysm (AAA) repair, with particular emphasis on a comparison of suprarenal versus infrarenal endograft placement.

METHODS

Ninety-nine patients (92 men; average age 68 years) who had undergone endovascular AAA repair between July 1995 and July 1999 and who had at least 12 months' follow-up were studied with spiral computed tomographic scans to identify suprarenal endograft deployment and renal infarction.

RESULTS

Among the 193 renal arteries available for study, partial or complete transrenal endograft placement was found in 69 (36%). Sixteen (8.3%) renal infarctions were identified by the postoperative imaging studies. Perfusion of these kidneys was supplied by 6 (8.7%) of the 69 overstented renal arteries and 7 (5.6%) of the 124 uncovered arteries (p > 0.05). In the 3 other cases, intentional accessory renal artery occlusion by the stent-graft fabric led to frank segmental renal infarctions, which were visualized as territorial-perfusion defects affecting up to 27% of the renal volume. In the other 13 infarcted kidneys, the punctate deficits involved <10% of the parenchymal volume. Renal retention values were unaffected in 15 (94%) of 16 patients.

CONCLUSIONS

Documented renal infarctions following endovascular aortic stent-graft placement are not common and do not appear to be associated with suprarenal endograft fixation.

An in situ adjustable endovascular graft for the treatment of abdominal aortic aneurysms

Twenty-nine patients underwent placement of the Teramed Ariba Endovascular Graft System (Maple Grove, Minn) as part of a European Feasibility study (14 patients) and a US phase I trial (15 patients). Salient features of this modular endograft system include a crimped seamless polyester bifurcation graft supplied in three diameters and three iliac limb lengths, three types of nitinol stents including a suprarenal stent with aortic barbs, a flexible delivery system capable of controlled incremental sheath retraction, a flexible tapered lead balloon, and a telescoping technique for adjusting the length of graft coverage during surgery over a range of 3 cm. Twenty-eight of the 29 patients met the primary objective of this evaluation, which was to confirm the safety of the system, defined as the absence of major device-related adverse events and type I, III, or IV endoleaks within 1 month of implantation. Three major adverse events occurred within 1 month of discharge: renal failure, which was related to deployment of the device close to the renal arteries; pulmonary edema, which was related to the procedure but not the device; and peripheral ischemia, which was related to the patient's pre-existing condition. Seven patients had type II endoleaks noted by means of computed tomography scanning at 1 month; the endoleaks were identified by means of angiography and classified at the time of surgery. There were no deaths, aneurysm ruptures, stent-graft migrations, stent fractures, graft ruptures, graft thromboses, or surgical conversions at 1 month. This early clinical experience indicates that the Ariba Bifurcated Endovascular System can be safely implanted.

Analysis of initial CT findings after endovascular repair of abdominal aortic aneurysm

PURPOSE

To determine the spectrum and frequency of specific computed tomographic (CT) findings in the acute period after endovascular repair of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

CT images obtained 1--3 days after endograft placement were evaluated in 88 patients. The images were analyzed for stent position, appearance of endograft components, perigraft leak, and postoperative findings including air and acute thrombus within the aneurysm and air surrounding the femoral-femoral bypass graft. Findings that could be misinterpreted as perigraft leak were evaluated.

RESULTS

Fifteen (17%) of 88 patients had perigraft leak in the acute postoperative period. The bare segment of the proximal self-expanding stent covered one or both renal arteries in 54 (61%) patients. One patient had CT evidence of renovascular compromise. Postoperative air was within the aneurysmal sac in 51 (58%) patients and surrounded the femoral-femoral bypass graft in 67 (94%) of 71 patients in whom the grafts were evaluated with CT. Mottled attenuation within the aneurysmal sac was seen in 50 (57%) patients. Forty-six (52%) patients had calcifications within longstanding thrombus. In 31 (35%) patients, findings that could have been misinterpreted as perigraft leak were identified.

CONCLUSION

Accurate analysis of CT findings after endovascular AAA repair requires careful review of all available CT images (preprocedural and pre- and postcontrast) and clear understanding of specific stent-graft components and placement.

Accuracy of plastic replica of aortic aneurysm using 3D-CT data for transluminal stent-grafting: experimental and clinical evaluation

PURPOSE

To plan stent-grafting for aortic aneurysms with complicated morphology, we prepared life-sized aortic replicas by laser stereolithography using helical 3D--CT data. The accuracy of the replica was evaluated by measurement of vessel phantoms and clinical 3D--CT data.

METHOD

An imaginary aortic wall was created from helical CT images of the aorta, and a hollow plastic replica was produced by laser stereolithography. The accuracy of the replica was evaluated in five abdominal aortic aneurysms by experimental phantom studies and measurements of the replicas.

RESULTS

The mean difference in measurements between 3D--CT images and model vessels and between 3D--CT images and aortic replicas was 0.2 mm each. Therefore, the difference in measurements between real aortic aneurysms and the replicas was at most 0.4 mm.

CONCLUSION

The accuracy of the replica is satisfactory, making it useful for preoperative evaluation and simulation for stent-grafting.

Relationship between preoperative patency of the inferior mesenteric artery and subsequent occurrence of type II endoleak in patients undergoing endovascular repair of abdominal aortic aneurysms

OBJECTIVES

The purpose of this study was (1) to find out whether preoperative inferior mesenteric artery (IMA) patency (on radiographic imaging) predicts IMA-related endoleaks after endovascular repair of infrarenal abdominal aortic aneurysms, (2) to determine feasibility of measuring aneurysm sac pressures in patients with endoleaks, and (3) to report early evidence of effective endovascular obliteration of IMA endoleaks.

METHODS

We studied 76 consecutive cases of infrarenal aortic aneurysms that were repaired with an endovascular approach (March 1998-April 1999).

RESULTS

There were 13 (17%) endoleaks persistent 30 days after the procedure. Eleven (85%) of these 13 were IMA-related endoleaks, which were documented with selective superior mesenteric artery angiography. The preoperative finding (on computed tomographic scan) of a patent IMA does not always predict an IMA-related endoleak, but results in a statistically and clinically significant higher ratio of patients with IMA-related endoleaks in the immediate postoperative period (24% versus 3%, P <.035). In eight of the 11 patients with persistent IMA-related endoleaks, measurement of intra-aneurysm sac pressures was possible, and six of these patients had systemic pressures within the excluded aneurysm sac. Nine (82%) of 11 IMA-related endoleaks were successfully obliterated by means of selective IMA embolization.

CONCLUSIONS

Many endoleaks are caused by a patent IMA, and this can result in persistence of systemic pressure within the aneurysm sac. The preoperative finding (on computed tomographic scan) of a patent IMA is a predictor of increased rates of IMA endoleaks, and IMA endoleaks can be successfully obliterated through endovascular procedures, after endovascular abdominal aortic aneurysm repair.

Transrenal fixation of aortic stent-grafts for the treatment of infrarenal aortic aneurysmal disease

PURPOSE

We evaluated our early experience with the transrenal fixation of aortic stent-grafts to determine the efficacy of this procedure and its effects on renal artery patency and hemodynamics.

METHODS

Twenty-eight patients (22 men) had endoluminally placed modular bifurcated stent-grafts with a bare spring structure at the proximal end crossing the origin of both renal arteries; no patient with infrarenal fixation was included for analysis. The mean age of the patients was 75 +/- 7 years (range, 58-86 years); the mean aneurysm size was 5.8 +/- 0.8 cm (range, 4.7-7.2 cm). Eight patients had preoperative or intraoperative angiographic evidence of renal artery atherosclerotic disease, but only four vessels had luminal narrowing of 50% or greater. No complications were noted during stent-graft placement, and all patients have returned for follow-up visits, ranging from 1 to 12 months (mean follow-up, 6 +/- 4 months). Follow-up evaluations included clinical assessment, duplex ultrasound scan of the renal arteries and kidneys, and computed tomographic angiography.

RESULTS

No evidence of lobular or sublobular perfusion defects of the renal parenchyma was detected postoperatively. Two patients exhibited postoperative changes in renal artery hemodynamics-one progressing from a 30% diameter reduction to a greater than 60% diameter stenosis at the 12-month follow-up visit and one with a normal renal artery preoperatively having elevated flow velocities indicative of a greater than 60% stenosis at the 1-month visit. Of 19 patients with normal preoperative renal function, only one has had persistently elevated serum creatinine levels.

CONCLUSION

We conclude from this experience that the transrenal placement of open stents is safe and effectively excludes the aneurysm, potentially expanding the availability of this technique to more patients with a short infrarenal aortic neck. Long-term follow-up is essential to determine the overall efficacy of this technique and to identify potential effects on renal artery hemodynamics or kidney function.

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.

Patient selection for endovascular repair of aortoiliac aneurysms

PURPOSE

This study was conducted to establish criteria to aid in the selection of patients for endovascular repair of aorto-iliac aneurysms.

METHODS

Characterization of pertinent factors used to determine whether a patient is eligible to undergo stent-graft repair of an aorto-iliac aneurysm.

PRINCIPAL FINDINGS AND CONCLUSIONS

The determinant factor that dictates whether or not one is eligible to undergo endovascular repair of aorto-iliac aneurysm is the arterial anatomy of the affected area and its surrounding vessels. Some of the initial limitations imposed in this technology have changed such as an acceptance of much shorter neck than initially conceptualized, by the use of supra-renal stent deployment. However, unsolved issues remain regarding the differentiation of thrombus and atherosclerotic plaque in the infra-renal aortic region, iliac artery disease, and the need to have an enhanced flexibility of the delivery system for proper deployment in tortuous aortic necks. The question of long-term device durability remains the most important issue that has to be taken into consideration before one chooses minimally invasive endovascular approaches.

Aortic stent-grafting with transrenal fixation: use of newly designed spiral Z-stent endograft

PURPOSE

To evaluate the feasibility and efficacy of a newly designed stent-graft placed across the renal arteries for exclusion of abdominal aortic aneurysms (AAAs) with short or tortuous proximal necks.

METHODS

Among a group of AAA patients treated with endovascular grafting, 5 had tortuous proximal necks and 13 had necks <20 mm (mean 13 mm). In these 18 cases, a 2- to 3-cm uncovered segment of the stent-graft was placed transrenally using a catheter inserted into the renal artery as a guide for graft margin positioning. A newly designed stent-graft was constructed from a custom-made spiral Z-stent covered with a thin-walled Dacron material; the endografts were deployed through 16-F (aortoaortic model) or 18-F sheaths (bifurcated devices). Renal function was assessed by preoperative and postoperative measurement of urea nitrogen and creatinine. Aneurysm exclusion and renal artery patency were evaluated during follow-up using spiral computed tomography and angiography.

RESULTS

The stent-grafts were correctly placed at the intended site in all 18 patients. Renal function was not affected except transiently in 1 patient who developed bilateral renal artery stenoses 24 hours after the procedure; Palmaz stents were deployed in each renal artery to reestablish satisfactory blood flow. Of the 33 renal arteries crossed by the bare stent-graft segment, all were patent over a mean 14-month follow-up (range 7-24), including the patient with Palmaz stents implanted for postprocedural renal stenosis. Complete aneurysm exclusion was maintained in 15 (83%) of 18 patients; proximal leaks persisted in 3 patients, including 2 with severely angled proximal necks.

CONCLUSIONS

Transrenal placement of the uncovered leading edge of custom-made spiral Z-stent-based endografts appears feasible and clinically effective in the treatment of AAAs with short or tortuous proximal necks.

Postcatheterization pseudoaneurysms and arteriovenous fistulas: repair with percutaneous implantation of endovascular covered stents

PURPOSE

To assess the effectiveness and safety of endovascular covered stents in the management of pseudoaneurysms and arteriovenous fistulas after cardiac and vascular catheterization.

MATERIALS AND METHODS

Twenty-six endovascular covered stents were used to repair 16 pseudoaneurysms, nine arteriovenous fistulas, and one combined lesion after femoral arterial puncture for diagnostic coronary angiography and/or angioplasty. Fistulas and aneurysms were in the superficial femoral artery in 16 cases, in the deep femoral artery in six cases, and in the common femoral artery in four cases. Implantation was performed from the opposite femoral artery in most cases. It was not possible to treat three additional cases transcutaneously for technical reasons (three of 29 cases).

RESULTS

Percutaneous closure of the lesions with an endovascular covered stent was successful in 26 of 29 cases. Initial follow-up showed good stent patency. Two major complications were observed after stent implantation. During follow-up (about 1 year in 23 of 26 patients [88%]), stent thromboses were detected in four of 23 patients (17%) with follow-up color duplex flow imaging.

CONCLUSION

Implantation of endovascular covered stents is an effective and safe method for the percutaneous closure of pseudoaneurysms and arteriovenous fistulas. Thus, endoluminal vascular repair with covered stents offers an alternative therapeutic approach to vascular surgery in selected patients.

Endovascular repair of abdominal aortic aneurysms: where do we stand?

Endovascular repair of abdominal aortic aneurysms has evolved dramatically within the past few years. In light of the potential to reduce morbidity and mortality associated with open surgical repair, endoluminal grafting offers therapeutic options to patients who are not surgical candidates because of comorbidities. With the development of bifurcated devices, more complex aneurysms may be treated by endovascular grafting. Although successful placement of endovascular grafts requires a pronounced learning curve, including appropriate patient selection, midterm results seem consistent with those of traditional open repair of aneurysms. This review describes the current indications, minimal requirements, different devices and associated techniques, and potential complications of endoluminal repair of abdominal aortic aneurysms. Future aspects of endoluminal grafting are also discussed.

Custom bifurcated stent-graft for abdominal aortic aneurysms: initial experience

PURPOSE

To describe a custom bifurcated stent-graft for possible treatment of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

Five male patients (mean age, 76 +/- 6 years), who had AAA (mean diameter, 4.7 +/- 0.4 cm) and who were considered to be at high risk for conventional surgery, were treated with a custom modular bifurcated stent-graft constructed with bifurcated 24-mm x 12-mm (upper body diameter x iliac limb diameter) Cooley Veri-Soft Woven polyester grafts and Gianturco-Rösch Z stents. The stent-graft body was delivered through 20-22-F sheaths, and the contralateral iliac limb was delivered through a 16-F sheath by means of surgical exposure of the common femoral arteries. A flared distal limb extender (12 mm to 14 mm) was created for one patient to accommodate a large common iliac artery.

RESULTS

Stent-grafts were successfully deployed without complications in all five patients. There were no proximal or distal leaks. A lumbar-to-inferior mesenteric artery leak was seen in one patient at 24 hours. At 6-month follow-up, all devices were intact, with complete exclusion and shrinkage of the aneurysm in four of five patients. Aneurysm size remained stable in the one patient with a lumbar-to-inferior mesenteric artery leak.

CONCLUSION

A custom, bifurcated stent-graft was utilized for endovascular treatment of AAA. Long-term follow-up is necessary for the device.

Twin-tube endografts for aortic aneurysms: an experimental feasibility study

PURPOSE

To explore feasibility of twin-tube endografts (TTEGs) for treatment of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

AAAs were created in six dogs by overdilation of Palmaz stents. TTEGs made of seven 9.5-mm-diameter Gianturco Rösch Z (GRZ) stents and covered with PTFE were deployed simultaneously from both femoral arteries through 10-F sheaths to exclude the AAA. Follow-up aortography was performed immediately and at 2, 4, and 8 weeks. Two dogs were killed at 4 weeks and four were killed at 8 weeks. Gross and histologic examinations were performed.

RESULTS

AAA creation and TTEG placement were successful in all six dogs. TTEGs completely excluded AAAs in five dogs. Minor temporary perigraft leak was seen in one dog immediately after stent placement. Four dogs had TTEGs patent to termination at 8 weeks. In two dogs with oversized TTEGs, one of the twin endografts occluded at 2 weeks. At autopsy, TTEGs were formed in semicircular shape and histology did not show any significant inflammatory reaction.

CONCLUSION

TTEGs show promise for treatment of AAA, with the potential of reducing the introductory sheath size. Further experimental studies, particularly with TTEGs extended into iliac arteries, are warranted.

Perigraft air, fever, and leukocytosis after endovascular repair of abdominal aortic aneurysms

BACKGROUND

The postimplantation syndrome of fever and leukocytosis after endovascular repair of infrarenal aortic aneurysms has not been previously characterized and its etiology is not known.

METHODS

We studied the first 12 patients who underwent successful endovascular repair of infrarenal aortic aneurysms with Dacron-covered stent-grafts, as part of an ongoing phase II clinical trial. Sepsis syndrome evaluations (physical examination, urinalysis, chest radiograph, urine cultures, and blood cultures) were performed for all patients with postoperative temperature (T) greater than 101.4 degrees F. Computed tomography scans of the abdomen were performed, as part of the clinical protocol, on postoperative days 2 and 30.

RESULTS

Fever (T > 101.4 degrees F) was seen in 8 of 12 (67%) patients (P < 05). An additional 2 of 12 (17%) patients had low-grade fevers (100.3 degrees F, 100.6 degrees F). Only 2 of 12 (17%) patients remained afebrile postoperatively. Leukocytosis with counts over 11,000 white blood cells (WBC)/dL was observed in 7 of 12 (58%) patients (P < 05). Sepsis evaluations failed to identify any source of infection in 11 of 12 (97%) patients. Computed tomography scan evidence of perigraft air was noted in 8 of 12 (67%) patients. All patients were afebrile, had normal white blood cell counts, and were discharged within 1 week postoperatively. There has been no evidence of graft infection after 1 to 6 months of follow-up.

CONCLUSIONS

Fever and leukocytosis after stent-graft repair of aortic aneurysms does not represent evidence of systemic or graft infection and is not clearly related to nonspecific causes of postoperative fever and leukocytosis. Moreover, the finding of early postoperative perigraft air is not necessarily an indication of graft infection even when concurrently present with fever and leukocytosis.

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.