How Many Patients with Infrarenal Aneurysms are Candidates for Endovascular Repair? The Northern California Experience

Purpose:

To determine how many patients with abdominal aortic aneurysms (AAA) meet the anatomical selection criteria for AneuRx stent-graft repair in community hospitals of Northern California.

Methods:

The records were reviewed of 220 AAA patients (171 men, 49 women) who were considered for endovascular repair by the treating vascular surgeon at 28 community hospitals in Northern California between January and October 2001. Contrast computed tomographic angiography (CTA) and selective arteriography were performed at each institution and reviewed by a centralized, independent image-reading center. Selection criteria determined by the manufacturer and published in the indications for use were applied to each set of imaging studies. The number of patients who met inclusion criteria were recorded, as were the anatomical characteristics of each aneurysm.

Results:

The mean aneurysm size in the 220 patients was 55.3±0.7 mm. Among these patients, 122 (55%) were judged to be candidates for endovascular repair and 98 (45%) were considered ineligible. The primary anatomical reason for ineligibility was a short infrarenal neck in 43 (44%) patients, followed by a large proximal neck diameter (25, 25%), iliac aneurysms (10, 10%), extremely tortuous or calcified neck (7, 7%), iliac occlusion (6, 6%), and small distal aortic bifurcation and accessory renal arteries (5, 5%). Four (4%) patients were classified as non-candidates due to poor quality imaging. There was no difference in aneurysm diameter (54.0±0.8 versus 57.1±1.2 mm, p=NS) or age (72.2±1.2 versus 74.6±2.2 years, p=NS) between candidates and non-candidates. However, proportionally more men (60%) than women (39%) were eligible for endovascular repair with the AneuRx stent-graft (p<0.05). All 122 patients who were considered candidates for endovascular repair were treated, with successful stent-graft placement achieved in 121 (99%).

Conclusions:

Fifty-five percent of patients considered for endovascular AAA repair in community hospitals in Northern California met the anatomical selection criteria for the AneuRx stent-graft. Men appeared to be twice as likely to meet the eligibility requirements as women. Unfavorable infrarenal neck anatomy was the primary exclusion criterion for endovascular repair in this community setting.

Open abdominal aortic aneurysm repair is still necessary in an era of advanced endovascular repair

OBJECTIVE

Recent advances in endovascular aneurysm repair have overcome substantial anatomic barriers associated with short and challenging necks. With greater range to treat more difficult anatomy from an endovascular approach, one would assume the need of open surgical repair (OSR) would be diminished. The purpose of our study was to determine the need for OSR for abdominal aortic aneurysms, in a tertiary academic setting, with a moderate volume (10-15 cases/year) of fenestrated endografting being performed.

METHODS

An Institutional Review Board approved retrospective review was performed of all patients who underwent elective aortic aneurysm repair between January 2010 and July 2014. Computed tomography scans for patients who underwent OSR were reviewed and anatomic characteristics obtained. Instructions for use of (IFU) a commercially available fenestrated device (Cook Medical, Bloomington, Ind) were used to determine if open repair patients had anatomy amenable to advanced endovascular repair.

RESULTS

During the study interval, 415 patients underwent abdominal aortic aneurysm repair. Of those patients who underwent elective aneurysm repair, 105 patients had OSR. The study subsequently excluded 11 patients because they underwent secondary interventions after a failed endovascular repair and thus were not further evaluated. Also excluded were 18 patients who had OSR for an emergency intervention. The remaining 76 patients (35 female, 41 male; average age, 72 ± 8 years) had OSR and were outside the IFU of the fenestrated endovascular aneurysm repair (FEVAR) device. The average diameter of the abdominal aorta was 5.9 cm. Indications for OSR were an aneurysm neck <4 mm (71%), inclusion of at least 1 visceral vessel (69.7%), unilateral iliac artery aneurysms (15.5%), bilateral iliac artery aneurysms (14.3%), iliac artery tortuosity >40° of angulation (37.6%), extensive aortic thrombus (23.2%), and aortic neck angulation >45° (11.8%). Rejected patients had an average of 1.7 ± 0.8 anatomic constraints (range 1-4) that prevented use of the FEVAR device.

CONCLUSIONS

With evidence to support the strict adherence to IFU protocols of the FEVAR device in patients, our institution's practice has been to continue to perform open abdominal aortic aneurysm repair for patients with anatomy outside device protocols. Although it was thought that the decreased requirement of aortic neck required to deploy an endograft would lead to an increased patient population amenable to endovascular repair, there is still a clinically significant need for open aortic surgery.

Three-Year Experience with Modular Stent-Graft Devices for Endovascular AAA Treatment

Purpose:

To evaluate feasibility and present early results of endovascular abdominal aortic aneurysm (AAA) exclusion using modular stent-grafts.

Methods:

In a 3-year period ending July 1997, 201 patients were treated with self-expanding stent-grafts for AAAs with infrarenal necks ≥ 10 to 15 mm long and ≤ 32 mm wide; subtotal mural thrombus, calcification, and even angulation to some extent were acceptable, as were iliac arteries up to 18 mm wide. The patients were treated with either the Stentor/Vanguard device (178 cases) or the Talent endograft (23 cases). Follow-up on all patients was conducted at 3, 6, 12, 18, and 24 months.

Results:

The technical aneurysm exclusion rate was 89% (178/201). There were 18 primary endoleaks (9.0%; 2 proximal, 16 distal), 4 (2.0%) conversions to open surgery, and 1 (0.5%) failure to deploy the graft. Seven (3.5%) patients died in the perioperative period, 5 due to multiorgan failure early in the series and two of hemorrhagic complications. Five (2.5%) renal artery occlusions were encountered; in one case, the graft was removed after 3 weeks. Nineteen late endoleaks were found in follow-up, related primarily to the iliac limb graft extensions of the Stentor device, graft material problems, or unknown causes. To date, 10 primary and 13 secondary endoleaks have been treated endovascularly. Twenty (10.0%) graft-limb thromboses were treated either by thrombolysis, thrombectomy, or a femorofemoral bypass.

Conclusions:

Endovascular grafting is technically feasible and becomes easier with improvements of the introducer systems and the grafts. The seemingly high complication rate in this series is due to the liberal patient selection criteria.

Relocation of the Iliac Artery Bifurcation to Facilitate Endoluminal Treatment of Abdominal Aortic Aneurysms

Purpose:

To report a surgical technique to preserve the internal iliac arteries (IIAs) and facilitate endovascular repair of abdominal aortic aneurysms (AAAs) with extensive iliac artery involvement.

Technique:

A new iliac artery bifurcation is created surgically through an 8-cm lower left abdominal incision by implanting the IIA onto the distal external iliac artery either directly or by using a tube graft interposition. Careful technique is required to avoid embolic complications, but after relocating the bifurcation, aortic endografting can be performed, either simultaneously or staged, depending upon patient characteristics.

Conclusions:

Relocation of the iliac artery bifurcation appears to be a good alternative to preserve pelvic arterial flow in selected candidates for endoluminal AAA repair.

Abdominal Aortic Aneurysm Morphology in Candidates for Endovascular Repair Evaluated with Spiral Computed Tomography and Digital Subtraction Angiography

Purpose:

To analyze the morphology of abdominal aortic aneurysms (AAAs) and to study the usefulness of spiral computed tomography (CT) versus digital subtraction angiography (DSA) in the evaluation of patients for endovascular repair.

Methods:

Of 133 AAA patients (120 men, mean age 67 years, range 52 to 84) evaluated preoperatively with CT imaging, 77 endograft candidates (68 men) were also assessed with intra-arterial DSA. Arterial parameters were measured on axial CT scans and angiographic films for comparison.

Results:

Mean maximum AAA diameter was 58 ± 11 mm (range 39 to 95). Aneurysmal neck diameter was consistently smaller on DSA than on CT (20.7 ± 3.6 mm versus 23.0 ± 3.5 mm, p < 0.0001). The distance from the most distal renal artery to the aortic bifurcation was longer on angiography than on CT (mean difference 10.0 mm, p < 0.0001). There was a positive correlation between the maximum AAA diameter and the AAA length (r = 0.49, p < 0.0001) and an inverse relationship between the neck length and the neck diameter (r = −0.36, p < 0.0001). No correlation was found between the maximum AAA diameter and maximum iliac diameter, angulation, or length.

Conclusions:

AAA anatomy varies widely and independently of the aneurysm size. Therefore, the maximum size of the aneurysm is a poor predictor of whether or not an aneurysm is suitable for endovascular repair. The discrepancy between angiographic and axial CT measurements suggests that neither alone is sufficient as a preoperative imaging technique when evaluating a patient for an endovascular graft procedure.

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.

Crossing the limbs: a useful adjunct for successful deployment of the AneuRx stent-graft

PURPOSE

To describe a technique for deploying an AneuRx stent-graft in an abdominal aortic aneurysm (AAA) with an acutely angled aortic neck.

TECHNIQUE

In routine cases, the AneuRx stent-graft main body is positioned with the nose cone notch facing the contralateral side. In severely angulated aortic necks, however, the main body of the AneuRx stent-graft can be positioned with the nose cone notch and iliac limb gate facing the ipsilateral side; this dramatically reduces the acuity of the angle at the aortic neck and the iliac gate. This technique of "crossing the limbs" has been successfully used in 7 cases since FDA approval of the AneuRx device.

CONCLUSIONS

Proximal neck angulation is an important factor for successful endovascular AAA repair. Crossing the graft limbs reduces the effect of neck angulation on the proximal main body and may decrease the stress upon the contralateral limb gate, which may avoid graft gate disconnection and endoleak.

The AneuRx stent-graft since FDA approval: single-center experience of 230 cases

PURPOSE

To compare a single-center experience with the AneuRx stent-graft system before and after FDA approval to results from the multicenter phase II clinical trial.

METHODS

The medical records of 230 consecutive patients (218 men; mean age 74 years) undergoing AneuRx stent-graft implantation for abdominal aortic aneurysm (AAA) exclusion since September 1999 were reviewed to collect patient characteristics, aneurysm morphology, procedure variables, perioperative morbidity, mortality, and short-term outcome. These data were compared to the 30 patients treated at our institution during the AneuRx phase II clinical trial and to the overall multicenter trial data. Stent-graft difficulty was categorized from 1 (straight neck and access of appropriate size) to 4 (proximal neck <10 mm long or angulated >60 degrees and/or difficult access) based on aneurysm morphology.

RESULTS

Data from the 30 patients enrolled in the phase II trial at our institution were comparable in terms of patient characteristics and procedure variables to patients treated after FDA approval and to the multicenter data. However, the proportion of cases involving aneurysms with a more complex morphology (levels 3 and 4) rose 22% after FDA approval, reflecting a change in referral patterns. Our postoperative endoleak and morbidity rates increased nonsignificantly with respect to our own phase II experience (17% versus 6%, 18% versus 11%, respectively); however, they were not significantly different from the multicenter data. Reintervention was performed in 15 of 38 endoleak cases, mostly type I. Only 5 (2.1%) cases had a persistent endoleak at the time of discharge.

CONCLUSIONS

Since FDA approval of the AneuRx device, our endovascular practice has changed toward the management of increasingly more complex AAAs. Although we are attempting more challenging cases, we are able to maintain similarly high short-term success rates while offering stent-grafting to an increasing number of patients. These results suggest that more patients may be candidates for endoluminal graft placement than determined by the clinical trial selection criteria, provided that strict surveillance and long-term follow-up is maintained.

Computerized modeling based on spiral CT data for noninvasive determination of aortic stent-graft length

PURPOSE

To preprocedurally determine the correct length of a nonbifurcated endovascular prosthesis for abdominal aortic aneurysm (AAA) repair using a computerized model.

METHODS

A computer program was implemented to calculate the optimal intraluminal course of nonbifurcated stent-grafts from spiral computed tomographic (CT) images of the aortic lumen reconstructed at 2.5, 5, and 10-mm slice thicknesses. The algorithm was tested using 10 phantoms fabricated from 150-mm-long, 10-mm-diameter copper rods that were bent into shapes mimicking different aortic configurations. Midpoint coordinates and rod diameters were determined from each CT image by 3 independent observers and served as input parameters to the program. The influence of the different CT reconstructions on the calculated lengths and possible observer dependence were assessed using calculated length estimation errors. Spiral CT images from 20 consecutive AAA patients scanned before stent-graft implantation were also processed to evaluate the algorithm under clinical conditions.

RESULTS

Length estimation errors of the phantoms depended on the degree of bending as well as on the CT reconstruction slice thickness but were observer independent. Maximum errors were 7% for the 10-mm slices, 3.5% for the 5-mm slices, and 1.2% for a 2.5-mm reconstruction. The mean longitudinal shortening of the aorta due to vessel tortuosity was 9.1% +/- 4.8% among the 20 patients. Based on the results of the phantom study, errors of the calculated stent-graft lengths in patients were estimated to be approximately 1% for a 5-mm CT reconstruction increment and <2% for a 10-mm increment.

CONCLUSIONS

The proposed algorithm makes it possible to calculate noninvasively the correct length of straight stent-grafts under clinical conditions with a 1% to 2% error.

Sequential coil embolization of bilateral internal iliac artery aneurysms prior to endovascular abdominal aortic aneurysm repair

PURPOSE

To report the endovascular repair of concomitant aneurysms of the abdominal aorta and both internal iliac arteries.

CASE REPORT

A 72-year-old man with a 5.5-cm abdominal aortic aneurysm (AAA) extending to the right common iliac artery also presented with separate aneurysms of both internal iliac arteries. The patient refused conventional surgery, so an endovascular strategy was devised. Initially, the iliac aneurysms were sequentially coil embolized, allowing several weeks to elapse between the embolization sessions to encourage collateral development. A bifurcated Talent endograft was inserted successfully 8 months after the initial intervention; no evidence of endoleaks or mesenteric ischemia has been seen over a 1-year follow-up.

CONCLUSIONS

This case illustrates the feasibility of inducing collateralization prior to endovascular AAA repair that would jeopardize internal iliac artery circulation bilaterally. Sequential embolization of the internal iliac arteries over several months initiates this response, paving the way for eventual endovascular repair of the primary aortic aneurysm.

Endoluminal aortic grafting with renal and superior mesenteric artery incorporation by graft fenestration

PURPOSE

To explore the use of juxta- and suprarenal aortic segments for endograft fixation in abdominal aortic aneurysm (AAA) patients and to develop methods of graft implantation that use endograft fenestrations to preserve renal and visceral vessel perfusion.

METHODS

From August 1998 to May 2000, 13 AAA patients with unsuitable infrarenal aortic necks were treated with custom-designed endovascular grafts employing the juxta- and suprarenal aortic segments for proximal sealing. Flow to 33 renal and superior mesenteric arteries was maintained via graft fenestrations that were aligned by use of radiopaque graft markers. The fenestration-orifice interface for renal arteries was secured with modified balloon-expandable stents.

RESULTS

All fenestrated grafts were deployed as planned, and all target vessels (33/33) were preserved. Two patients did not receive any stents, one being the first in the series and another who had incorporation of a renal accessory artery only. Without the use of transgraft stenting, 5 renal arteries would have been occluded by the endograft or poorly perfused. Procedural success was 100%. No conversion to open operation or graft-related complications occurred. There was no primary endoleak in any patient by angiographic criteria. Two patients required additional surgical procedures related to access vessels. Periprocedural mortality at 30 days was nil. Follow-up ranging from 3 to 24 months on all patients has not demonstrated any proximal or distal endoleaks. One stented renal vessel has occluded; all other arteries remain patent at last examination.

CONCLUSIONS

This study has demonstrated the ability to successfully place a multifenestrated endoluminal graft in an aortic aneurysm using juxta- and suprarenal aortic segments to obtain a satisfactory seal. Stenting of the fenestration-renal ostium junction has helped to maintain renal patency.

A simple technique to improve the accuracy of proximal AAA endograft deployment

PURPOSE

To report a technique for overcoming the positioning errors caused by angulation and rotation of the proximal aortic neck when anteroposterior fluoroscopic imaging is used during endograft deployment.

TECHNIQUE

Aortic neck angulation and rotation were measured preoperatively using spiral computed tomographic angiography in sagittal and axial projections. Before proximal graft deployment, the proximal end of the endograft was centered in the field of view, and the position of the C-arm was adjusted to the aortic neck angulation. Using this technique, optimal positioning of the endograft relative to the true position of the renal arteries can be achieved.

CONCLUSIONS

C-arm angulation and rotation is helpful in facilitating perfect positioning for an optimal seal between the endograft and the infrarenal aortic neck.

Midterm changes in aortic aneurysm morphology after endovascular repair

PURPOSE

To study midterm changes in aortic aneurysm morphology after endovascular aneurysm repair.

METHODS

Of 94 patients with abdominal aortic aneurysms (AAAs) treated with endografts between November 1993 and August 1998, 84 were available for follow-up. Patients were evaluated preoperatively by spiral computed tomography (CT) and aortography; in follow-up, spiral CT scanning was performed at 1, 3, and 6 months and semiannually thereafter. Measurements of the aneurysm neck diameter, maximum aneurysm diameter, and the distance from the lowermost renal artery to the aortic bifurcation were made preoperatively and in follow-up.

RESULTS

Mean follow-up was 17.5 +/- 1.1 months; 56 (67%) patients were followed for 1 year and 28 (33%) for > or = 2 years. There was a median 2-mm increase (interquartile range [IQR] 0 to 3) in neck diameter at 18 months. However, a > or = 3-mm increase was seen in 18 (46%) of 39 patients examined at 18 months (median 4 mm, IQR 3 to 4, p = 0.0001). The maximum AAA diameter decreased by 9 mm (IQR 4 to 16, p = 0.0003) at 24 months, but after 18 months, no further interval decrease was seen. Aneurysms with a persistent endoleak showed either increasing or unchanged AAA diameters. There was no change in the renal artery to bifurcation distance.

CONCLUSIONS

The infrarenal aortic neck appears to dilate after AAA endografting, but only in a subset of patients. Shrinkage of aneurysms after successful stent-grafting seems to stop after 18 months, implying that the only indication of late failure in the absence of endoleak might be aneurysm enlargement. Graft-related endoleaks are often associated with an increase in aneurysm diameter.

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.

Aortic aneurysm size and graft behavior after endovascular stent-grafting: clinical experiences and observations over 3 years

PURPOSE

To assess the long-term safety and efficacy of aortic endografts in terms of clinical outcome, continuing aneurysm exclusion, and changes of aneurysm size and graft configuration.

METHODS

Between August 1994 and July 1997, 190 patients (176 men; mean age 68.7 years, range 40-87) with aortic and aortoiliac aneurysms were treated with endovascular stent-grafts (Stentor, Vanguard, and EGS) in a tertiary care municipal hospital setting. Follow-up involved clinic visits every 3 to 6 months with contrast-enhanced computed tomography (CT), color duplex, and plain abdominal radiographs at regular intervals; angiography was used selectively. All data were collected prospectively and entered into a computerized database.

RESULTS

Implantation was possible in 188 (98.9%) patients. Early conversion to open surgical repair was required in 14 (7.4%) patients. Primary endoleaks were detected in 32 (16.8%) patients. Perioperative mortality was 0.53% (1/190). During follow-up, 17 (8.9%) additional patients were converted to open repair over a mean 20.9 months. Thirty-seven secondary procedures to treat endoleaks and pelvic outflow occlusions were performed in 30 (15.8%) patients. Changes in stent configuration suggestive of endograft disintegration were observed in 31 (29.8%) of 104 abdominal radiographs. Intraluminal layering of thrombus was seen on contrast-enhanced CT images in 20 patients. A significant trend (chi(2)4 = 12.34, p < 0.025) toward aneurysm enlargement was seen in patients with persistent endoleaks at a mean 18-month follow-up.

CONCLUSIONS

Although endoleaks after aortic stent-graft placement tend to cause ongoing aneurysm growth, we have also observed aneurysm shrinkage despite ongoing endoleak. The presence or absence of an endoleak in itself may be a poor predictor of successful stent-graft therapy. Lifelong surveillance is needed to assure successful aneurysm exclusion and stability or shrinkage of the aneurysm sac. Technical improvements in stent materials and design are necessary to guarantee long-term stability and safety of the device.

Can preoperative spiral CT scans alone determine the feasibility of endovascular AAA repair? A comparison to angiographic measurements

PURPOSE

To determine whether computed tomography (CT) alone can be used for excluding patients from endovascular repair for abdominal aortic aneurysms (AAA).

METHODS

Among 71 patients evaluated for endovascular AAA repair using spiral CT imaging and angiography, 31 were selected who had both studies performed within 6 months of each other using a graduated measuring catheter or guidewire. Measurements of aneurysm neck diameter, neck length, and infrarenal aortic length were made from the CT and angiographic images using handheld calipers with calibration markers as guides. Infrarenal aortic length and neck length were determined from CT images by multiplying the width of the cuts by the number of slices between the lowest renal artery and the aortic bifurcation or the top of the aneurysm, respectively.

RESULTS

CT neck diameter measurements differed significantly from the angiographic dimensions (6.3 +/- 5.1-mm mean difference, p < 0.001). In the majority of patients (25, 81%), CT neck diameters were larger (mean 7.3 +/- 3.8 mm). The mean difference in neck length measurements was 0.5 +/- 15.9 mm (p = NS). Twenty-two (71%) patients had aortic length measurements that were longer on the angiogram (mean 15.4 +/- 17.2 mm, p = NS). Five patients who would have been excluded as candidates based on overestimated CT neck diameter measurements subsequently underwent successful endovascular aneurysm repair.

CONCLUSIONS

Considerable discrepancies exist between preoperative neck diameter and infrarenal aortic length measurements obtained from CT scans and angiograms used to evaluate candidates for endovascular aortic aneurysm repair. CT alone may not be adequate for predicting the feasibility of endovascular AAA repair.

A narrow-waisted abdominal aortic aneurysm complicating endovascular repair

PURPOSE

To present a case in which a narrow waist in an abdominal aortic aneurysm (AAA) complicated endovascular repair using a modular bifurcated stent-graft.

METHODS AND RESULTS

A 68-year-old man underwent endovascular repair of a 5.9-cm asymptomatic AAA with a self-expanding modular bifurcated stent-graft. After insertion and deployment of the stent-graft, the intraoperative completion angiogram disclosed unexpected incomplete deployment of the contralateral iliac limb due to a narrow waist in the aortic aneurysm. Subsequent angioplasty did not increase iliac stent-graft diameter. At follow-up, a tapered course of the contralateral iliac leg persisted, without hemodynamic significance.

CONCLUSIONS

A narrow waist in an AAA may be considered an additional important anatomical characteristic in assessing suitability for endovascular repair.

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.

Endograft planning without preoperative arteriography: a clinical feasibility study

PURPOSE

To investigate an alternative method of preprocedural planning for aortic endografting based solely on spiral computed tomography (CT) with 3-dimensional (3D) reconstruction without preoperative arteriography.

METHODS

From August 1997 to April 1998, 25 consecutive patients with abdominal aortic aneurysms (AAA) were evaluated for endovascular repair by spiral CT scans (2-mm slice thickness) and computerized 3D model construction. No additional imaging for planning was performed. The aortoiliac dimensions, thrombus load, calcification, and vessel tortuosity were measured and evaluated from the 3D model of the aortoiliac segment. These data were used for selecting the patients; the configuration, diameter, and length of the endograft; and the attachment sites for deployment.

RESULTS

Primary procedural success was 92% (23/25). All endografts were deployed as planned, and there were no conversions to open repair. Six patients required adjunctive procedures for delivery system access or for iliac aneurysm exclusion, as predicted by the 3D model. Mean procedural time was 91 minutes (range 24 to 273). Two (8%) type II (side branch) endoleaks both sealed spontaneously within 1 month. No graft-related complications or death occurred, for a 30-day technical success rate of 100%.

CONCLUSIONS

This computerized 3D model provided accurate data for preoperative evaluation of the aortoiliac segment for endovascular AAA repair. Satisfactory technical outcomes for aortic endografts can be achieved without the use of preprocedural invasive imaging.