Abdominal aortic aneurysms: preliminary technical and clinical results with transfemoral placement of endovascular self-expanding stent-grafts

Stent-Graft Placement in Atherosclerotic Descending Thoracic Aortic Aneurysms: Midterm Results

Purpose:

To determine midterm durability and need for reinterventions after stent-graft placement in atherosclerotic descending thoracic aortic aneurysms.

Methods:

Fifty-four patients (38 men; mean age 68 years, range 33–87) underwent stent-graft repair of chronic atherosclerotic aneurysms of the descending thoracic aorta between November 1996 and December 2002. Acute aortic syndromes (type B aortic dissections, perforating ulcers, and traumatic dissections) were excluded from analysis. Two types of commercially available stent-grafts were used (Talent and Excluder).

Results:

The primary technical success rate was 94.4%. In-hospital mortality was 3.7% (2/54). No adverse neurological events were encountered. Of 3 (5.6%) early type I endoleaks, 2 (3.7%) required reintervention; the other type I endoleak closed spontaneously. Mean follow-up was 38 months (range 1–72) in the 52 surviving patients. Four (7.7%) type I, 7 (13.5%) type II, and 4 (7.7%) type III endoleaks were seen. Three 3 patients had additional treatment for endoleaks (proximal stenting [type Ia], open thoracoabdominal repair [type Ib], and embolization [type II]). Two of the 3 reinterventions were performed in the first year of follow-up. One additional patient with a type Ia endoleak not suitable for reintervention is under close observation. There were no differences in the number of endoleaks between the 2 types of stent-grafts. Three-year event-free survival was 63%.

Conclusions:

Midterm durability of endovascular stent-graft placement in atherosclerotic descending aortic aneurysms seems promising, as the rate of endoleaks requiring reintervention is acceptably low. In our series, endoleak formation occurred during the first year after stent-graft placement, so close follow-up of patients after aortic aneurysm repair is crucial. Further studies are warranted to evaluate long-term durability of this new treatment modality.

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.

Two-Center German Experience with Aortic Endografting

Purpose:

To report the results of a two-center study of endovascular abdominal aortic aneurysm (AAA) exclusion using a polyester-covered nitinol stent-graft.

Methods:

Candidates were evaluated with arteriography and computed tomography. Criteria for endovascular therapy were a proximal aortic neck > 10 mm in length and < 25 mm in diameter, no bilateral internal iliac artery involvement in the aneurysm, no markedly tortuous common iliac arteries (CIAs) or CIAs < 7 mm in diameter, and no superior mesenteric artery occlusive disease. Patients were treated with the Mialhe Stentor and Vanguard stent-grafts in either tube or bifurcated versions.

Results:

Between August 1994 and November 1996, 149 patients (mean age 67 years, range 49 to 90) were admitted to the study. Overall primary technical success (aneurysm exclusion without endoleak) was 87% (130 patients): 78% (7 patients) for tube grafts and 88% (123 patients) for bifurcated endografts. The rate of local, remote, or systemic complications was 10.8%, with a 30-day mortality rate of 0.7%. During an average 13.5-month follow-up, there were no late deaths. Four of 20 endoleaks sealed spontaneously, 14 were treated with endoluminal techniques, and 2 remain untreated by patient request. Three graft limb thromboses occurred; one was treated surgically, one with lytic therapy, and one was untreated. Secondary patency was 96%.

Conclusions:

Endoluminal repair of infrarenal AAAs using straight or bifurcated grafts is a feasible alternative to conventional surgical repair. Longer follow-up and more experience with refined endograft models will elucidate the durability of this endovascular approach to treating AAAs.

Treatment of Traumatic False Aneurysm of the Thoracic Aorta with Endoluminal Grafts

Purpose:

Traumatic false aneurysms of the thoracic aorta presenting at a time remote from the original injury are a rare but complex problem. The treatment of a traumatic false aneurysm by endovascular techniques may offer many advantages over conventional open surgery.

Methods and Results:

Two male patients presented with traumatic false aneurysm of the thoracic aorta after being treated emergently for visceral injuries from a gunshot wound in one and an automobile accident in the other. In both cases, the aneurysm was situated so that only the T11 intercostal artery would be sacrificed by endoluminal exclusion. Commercially available endoluminal stent-grafts (Talent) were deployed successfully. Recovery in both patients was rapid and uneventful with no neurological sequelae. Spiral computed tomographic scans at 1 year indicated sustained aneurysm exclusion and satisfactory endograft position.

Conclusions:

A customized endoluminal stent-graft can be used with great accuracy to exclude thoracic false aneurysms, avoiding the potential complexity and morbidity of an open thoracic approach.

Morphometry and Classification in Abdominal Aortic Aneurysms: Patient Selection for Endovascular and Open Surgery

Purpose:

To evaluate the anatomic morphology of abdominal aortic aneurysms (AAAs) and compose a classification system to facilitate patient selection for endovascular graft (EVG) repair.

Methods:

Data on 242 consecutive AAA patients evaluated on a nonemergent basis in a 3.5-year period to July 1996 were prospectively entered into a registry. Patients were examined using sequential intravenous spiral computed tomographic angiography and intraarterial digital subtraction angiography. The data collected and analyzed included: diameters of the supra- and infrarenal aorta, aneurysm, aortoiliac bifurcation, and iliac arteries; lengths of the proximal neck, distal cuff, and aneurysm; degrees of iliac artery tortuosity; and occlusion of the visceral, renal, or iliac arteries.

Results:

The 242 aneurysms could be easily grouped into three distinctive categories related to the extent of the aneurysmal disease. Type I AAAs (11.2%) had nondilated, thrombus-free infrarenal (15 mm) necks and distal (10 mm) cuffs appropriate for EVG anchoring. In type II and its subgroups (72.3%), a sufficient proximal neck was present, but the aneurysm extended into the iliac arteries; 56% of these were eligible for a bifurcated endograft. In type III (16.5%), a sufficient proximal neck was missing, independent of distal involvement. In all, 51.7% were good EVG candidates based on AAA morphology. Taking into consideration relevant concomitant vascular diseases, proximal iliac kinking, and iliac, renal, or visceral occlusive disease, only 30.2% of the population were potential candidates for an efficient and secure EVG repair using the devices currently available.

Conclusions:

In contrast to classical open repair, detailed preoperative measurements are recommended for EVG planning. The use of liberal EVG indications may lead to a higher incidence of complications, whereas restrictive morphology-based selection criteria may offer excellent results.

Endoleak as a Complication of Endoluminal Grafting of Abdominal Aortic Aneurysms: Classification, Incidence, Diagnosis, and Management

The inability to obtain or maintain a secure seal between a vessel wall and a transluminally implanted intra-aneurysmal graft is a complication unique to the evolving technique of endovascular aneurysm exclusion. Because the term “leak” has long been associated with aneurysm rupture, the term “endoleak” is proposed as a more definitive description of this phenomenon.

Embracing both persistent blood flow into the aneurysmal sac from within or around the graft (graft related) and from patent collateral arteries (nongraft related), endoleak can be classified as primary or secondary depending on the time of occurrence (within 30 days of implantation or following apparent initial seal, respectively).

Diagnostic techniques to detect endoleak include arteriography, intraprocedural pressure monitoring, contrast-enhanced computed tomography, abdominal X ray, and duplex scanning. Management strategies for endoleak range from observation with periodic imaging surveillance to correction by additional endoluminal or surgical procedures.

Standardization of the terminology describing this important sequela to endovascular aneurysm exclusion should facilitate uniform reporting of clinical trial data vital to the evaluation of this emerging technique.

Diameter of Large Balloons Used in Endoluminal Graft Deployment Varies with Inflation Pressure

Purpose:

To evaluate the characteristics of large-diameter balloon catheters used during endoluminal repair of aortic aneurysms.

Methods:

Thirty-three large balloon dilatation catheters in the diameter range of 15 to 30 mm were measured at controlled pressures from 1 to 4 atm. The balloons were inflated with water using an inflation syringe connected to a pressure transducer. Diameters at stable pressure and pressure changes against time were recorded for each balloon.

Results:

Dilation catheters in the range of 15 to 20 mm in diameter were significantly smaller (p < 0.005) than their nominal diameter at 1 and 2 atm; they reached nominal diameter only at the relatively high pressure of 4 atm. Most larger diameter balloons (25 and 30 mm) did not attain their nominal diameter even with pressures up to 4 atm. All sizes of balloon catheters tested became relatively compliant at pressures > 3 atm.

Conclusions:

The large balloon catheters tested in this study were designed for arterial angioplasty or valvuloplasty. They attained a significantly smaller size than their nominal diameter at pressures < 3 atm and became compliant at pressures exceeding 3 atm. Interventionists should be aware of these characteristics when using balloon catheters such as these during endoluminal graft deployment. Large balloons that reach predictable diameter at lower pressures should be designed specifically for use in endoluminal graft procedures.

Three-Year Experience with the White-Yu Endovascular GAD Graft for Transluminal Repair of Aortic and Iliac Aneurysms

Purpose:

To report a > 3-year experience with a modular, balloon-expandable endovascular graft used for aneurysm exclusion in the aorta and other arteries.

Methods:

The customized White-Yu Endovascular GAD Graft, a woven polyester prosthesis with an intrinsic Elgiloy wire graft attachment system along the body of the graft, is a flexible endograft design available in straight, tapered, and bifurcated versions that can be delivered transluminally through 18F to 24F sheaths.

Results:

Since July 1993, 93 patients have received the White-Yu endograft for treatment of 76 abdominal aortic, 3 thoracic aortic, 13 iliac, and 1 popliteal aneurysms. Of the 79 aortic procedures, 39 involved straight tube grafts, 20 were tapered aortoiliac models, and 20 were bifurcated devices. Success rates for tube grafts were 81% in the abdominal aorta and 100% for the thoracic aorta; 5 primary endoleaks (14%) and 2 conversions to surgery (5.6%) occurred with this graft type. Aortoiliac grafts were deployed successfully in 95% (19/20) of cases with 1 conversion (5%) due to thrombosis. Seventy-five percent of the bifurcated endograft procedures were successful, with 4 conversions (20%) for technical failures and 1 graft thrombosis. Four additional endografts were deployed to treat two primary and two secondary endoleaks in tube graft patients. Two access-related arterial injuries were treated surgically. There was one case of embolus to the distal femoral artery but no microembolization. Overall perioperative (30-day) mortality was 3.1%. Over a mean 18-month follow-up (range 2 to 39), no late graft thrombosis, stenosis, or graft migration has been seen on CT scans or X ray. Endoleak has not been detected in any aortoiliac or bifurcated graft. Aneurysm size has diminished consistently in successfully treated cases.

Conclusions:

The White-Yu endograft appears to offer a safe, efficacious, and minimally invasive means of excluding aneurysms from the circulation. Improvements in patient selection, surgical techniques, and equipment have reduced the incidence of endoleak and conversion to open repair over the course of the evaluation.

Abdominal Aortic Aneurysms: Experience with the Ivancev-Malmö Endovascular System for Aortomonoiliac Stent-Grafts

Purpose:

To describe a component-based aortomonoiliac stent-graft system and the first clinical results achieved with this device in endovascular abdominal aortic aneurysm (AAA) repair.

Methods:

From November 1993 to October 1996, 45 patients aged 60 to 86 years underwent endoluminal exclusion of true AAAs (median diameter 60 mm) involving the common iliac arteries (median diameter 16 mm right and 15 mm left) using unilimb stent-grafts deployed with the Ivancev-Malmö system.

Results:

Six immediate conversions occurred in the beginning of the series due to endografts that were too short. Complications, including 2 inadvertent renal artery occlusions, 7 kinked grafts, 6 iliac artery dissections, and 3 perioccluder leaks, were prominent features in the first 15 patients. Five patients died in the postoperative period, four of whom were nonsurgical candidates. There were five significant stent-graft migrations: one 3 weeks after surgery due to mechanical injury of the proximal stent and four after 1 year owing to continuous dilation of a wide proximal neck, stent-graft placement in a conical, thrombus-lined proximal neck, and two instances of proximal extension separation from the main graft. Translumbar aneurysm perfusion required embolization in 3 patients.

Conclusions:

Despite early complications associated with a learning curve, exclusion of large AAAs using unilimb stent-grafts is feasible. Strict inclusion criteria are necessary in order to improve mortality among nonsurgical candidates and minimize the risk for late migration.

Successful Endoluminal Repair of Arterial Aneurysms by Wallstent Prosthesis and PTFE Graft: Preliminary Results with a New Technique

Purpose:

To describe a new method of endovascular aneurysm exclusion using a Wallstent-PTFE vascular prosthesis in patients at high risk for surgery.

Methods and Results:

Two patients with significant comorbidities refused surgery in favor of endoluminal grafting for treatment of aneurysms in the abdominal aorta and popliteal artery, respectively. Both endovascular procedures were performed percutaneously with local anesthesia using a low-profile customized endograft constructed of thin-walled, predicted polytetrafluoroethylene (PTFE) graft mounted on a Wallstent. In both cases, the aneurysm was excluded from the arterial circulation; there were no postprocedural complications. Follow-up evaluation with appropriate imaging at 8 months (popliteal aneurysm) and 2 months (abdominal aneurysm) revealed no endoleaks.

Conclusions:

Our preliminary results indicate that the Wallstent-PTFE graft, with its smaller diameter and flexible design, offers significant advantages over currently available devices for repair of arterial aneurysms. This method obviates the need for general anesthesia or surgical exposure for arterial repair, which would increase the risk of the procedure in these patients.

Regional Anesthesia for Endovascular Treatment of Abdominal Aortic Aneurysms

Purpose:

To investigate the feasibility of regional anesthesia for endovascular repair of abdominal aortic aneurysms (AAAs).

Methods:

Since February 1995, 21 patients (17 men and 4 women; median age 67 years, range 49 to 80) have been treated with endovascular technique for true infrarenal AAA using Mialhe Stentor bifurcated grafts. A single dose of spinal anesthesia combined with epidural anesthesia was used in all procedures. Electrocardiography and arterial blood pressure were monitored.

Results:

No cases of emboli, hematoma, or graft migration were seen, and there were no reoperations or conversions to open operation. Arterial blood pressure was stable at a satisfactory level from induction of anesthesia throughout the procedure, and there was no period of clinically significant hypotension during any implantation. One patient died on the second postoperative day from cardiac and renal insufficiency. Three endoleaks were observed during the procedure; one healed spontaneously within 5 weeks, and the other two were repaired by endovascular techniques after 1 and 4 months, respectively. During follow-up, one patient died at 6 months from pancreatic carcinoma.

Conclusions:

The application of regional anesthesia is feasible for endovascular treatment of AAA. The arterial blood pressure remained stable throughout the procedure, and all patients, with two exceptions, were mobilized on the first day and placed on a regular diet. Based on these early results, it appears that regional anesthesia is feasible, effective, and safe for endovascular AAA repair.

Ultrasound Imaging during Endovascular Abdominal Aortic Aneurysm Repair Using the Stentor Bifurcated Endograft

Purpose:

To evaluate different ultrasound modalities during implantation and follow-up of endovascular grafts for abdominal aortic aneurysm (AAA) exclusion.

Methods:

Between February 1995 and May 1996, 18 patients (14 men; aged 49 to 80 years, mean 67) were treated with endovascular intervention for infrarenal AAA. Seventeen patients received Mialhe Stentor bifurcated grafts, while one patient was treated with a straight graft for pseudoaneurysm. During and after the implantation, 3.25- and 5-MHz annular array ultrasound probes were used for transabdominal visualization of the endograft. Intravascular ultrasound was applied in combination with angiography for postoperative control.

Results:

Intraprocedurally, transabdominal two-dimensional (2D) ultrasound successfully monitored guidewire passage from the groin into the main part of the bifurcated endograft for implantation of the second limb. All implantation procedures were technically successful, but four endoleaks were identified intraprocedurally by 2D ultrasound and angiography. One healed spontaneously, two were treated with endovascular techniques at 1 and 4 months, and the last leak was scheduled for repair when the patient died of probable myocardial infarction at 2 months. During follow-up, 2D ultrasound successfully visualized all the endografts; no endoleaks were found in up to 18 months of surveillance.

Conclusions:

Transabdominal ultrasound imaging could be valuable in bifurcated endograft deployment both for guiding guidewire insertion and for controlling wire position before the second graft limb is connected to the main graft. Provided that satisfactory visualization of the entire endograft can be obtained, ultrasound examination may possibly replace arteriography and computed tomographic scanning as a follow-up investigation.

Interventional radiology: a half century of innovation

The evolution of modern interventional radiology began over half century ago with a simple question. Was it possible to use the same diagnostic imaging tools that had revolutionized the practice of medicine to guide the real-time treatment of disease? This disruptive concept led to rapid treatment advances in every organ system of the body. It became clear that by utilizing imaging some patients could undergo targeted procedures, eliminating the need for major surgery, while others could undergo procedures for previously unsolvable problems. The breadth of these changes now encompasses all of medicine and has forever changed the way we think about disease. In this brief review article, major advances in the field, as chronicled in the pages of Radiology, will be described.

Unusual complications of endovascular repair of the thoracic aorta: MDCT findings

With the development of minimally invasive surgical techniques, endovascular stent-graft placement has become an accepted and widely used alternative to the traditional surgical repair of aortic disease and is gaining acceptance as the treatment of choice. Many studies show that endovascular stent-graft therapy is safe and effective, although complications related to this treatment are also recognised. Although the incidence of major complication is low, neurological sequelae remain the major concern of endovascular repair. With growing experience, however, the spectrum of mid- and long-term complications has broadened to include potentially disastrous events, other than paraplegia or stroke, that require diligent surveillance. Three-dimensional data sets acquired quickly by multidetector computed tomography (MDCT) allow multiplanar reformations and 3D viewing, as well as quantitative assessment of vessel lumens, walls and surroundings. Although a large portion of radiologists will not be involved in the actual endograft deployment, many will be involved in the interpretation of postprocedural surveillance studies. Accordingly, the goal of this report is to summarise our experience with the presentation, diagnostic approach, management and outcomes of these unusual, but potentially catastrophic, postendovascular aortic repair complications to highlight their significance and increase familiarity with them among the imaging community. Increasing awareness of these complications may facilitate rapid diagnosis and/or triage and treatment.

A retrospective review of Palmaz stenting of the aortic neck for endovascular aneurysm repair

BACKGROUND

To review the aortic neck characteristics, graft types, and technical results of Palmaz stent placement as an adjunct to endovascular aneurysm repair (EVAR).

METHODS

A retrospective review of 110 consecutive EVAR cases identified 18 cases in which Palmaz stents were placed as an adjunct to EVAR. Graft types, hostile aortic neck features (neck diameter: >26 mm, length: <15 mm, angulation: >60°, reverse taper necks), and treatment success were identified.

RESULTS

Technical success in the placement of a proximal Palmaz stent was achieved in 17 of 18 cases. Palmaz stenting was attempted for the treatment of type I endoleak in 17 of 18 patients. One prophylactic stent was deployed in the setting of hostile neck anatomy. Proximal stent deployment resulted in immediate treatment success of type I endoleaks in 16 of 17 patients-one failure occurred in a patient who presented with a delayed type I endoleak. Analysis of aortic neck anatomy revealed that two of 18 patients had no criteria for a hostile neck, seven had one criterion, and nine met at least two criteria. With respect to stent-graft types, nine of 18 (50%) cases used the Endologix Powerlink, six used Gore Excluder, two used Cook Zenith, and one used Medtronic Talent. With a mean follow-up of 254 days, 16 of 17 type I endoleaks remain resolved.

CONCLUSIONS

With proper patient selection and additional adjunctive treatments, Palmaz stenting can effectively treat proximal type I endoleaks.

Role of multidetector computed tomography in evaluating complications following endovascular repair of aortic aneurysm

Objective:

To study the role of multidetector computed tomography (MDCT) in evaluating various complications following endovascular stenting of aortic aneurysms.

Materials and Methods:

Over a period of 2 years (June 2005 to June 2007), 50 patients with aortic aneurysm on computed tomography (CT) angiogram were prospectively studied. Images were acquired on a 64 slice multidetector row CT scanner (GE—LightSpeed VCT) after intravenous administration of nonionic iodinated contrast. Nineteen patients underwent endovascular stent-graft repair based on their medical and surgical risk factors. Stent-graft related complications were recorded by CT angiography and analyzed using descriptive statistics.

Results:

Most common complication related to the endovascular stent-graft placement was endoleak (44.4%), followed by puncture site hematoma (27.8%), thrombotic occlusion of a limb of the bifurcated stent graft, kinking of the stent-graft, and difficult catheterization with intimal tear in the common iliac artery were 5.6% each. Poststent diameter of the aneurysm was an important predictor of endoleaks. All the patients with either increase or no change in the aneurysm size had endoleaks.

Conclusion:

MDCT angiography is an important modality in identifying, describing, and following up the various complications following endovascular repair of aortic aneurysms, endoleaks being the most common complication. Decrease in the poststent diameter of the aneurysm suggested a good outcome.

Transluminal endovascular stent grafting of aortic dissections and aneurysms: a concise review of the major trials

Transluminal endovascular repair of the vascular system is rapidly emerging as a leading therapeutic modality for aortic dissections and aneurysms. The use of transluminal endovascular stent grafting has been used to intervene successfully on the aorta and its major branch vessels. There have been several studies examining transluminal endovascular stent grafting of thoracic aortic aneurysms, dissections, and abdominal aortic aneurysms. This paper reviews some of the major trials of transluminal endovascular stent grafting as well as its major limitation, endoleak.

Results After Endovascular Stent Graft Placement in Atherosclerotic Aneurysms Involving the Descending Aorta

BACKGROUND

The purpose of this study was to determine durability and need for reinterventions after endovascular stent graft placement in atherosclerotic aneurysms involving the descending aorta.

METHODS

We performed a prospective follow-up analysis of a consecutive series of 79 patients undergoing endovascular stent graft placement due to atherosclerotic aneurysms involving the descending aorta between 1996 and 2006. Acute aortic syndromes were excluded from this analysis. Mean follow-up was 42 months (range, 1 to 108 months). Data were collected for in-hospital mortality, occurrence of early and late endoleaks, reintervention due to early and late endoleaks, and survival.

RESULTS

In-hospital mortality was 6.3% (n = 5). Two of these patients underwent emergent treatment. Early type I and III endoleaks were observed in 29% of patients (n = 23). The assisted primary endoleak rate was 11%. Late type I or III endoleaks occurred in 21% (n = 17). At 1, 3, and 5 years, overall actuarial survival was 96%, 86%, and 69%, and event-free survival was 90%, 82%, and 65%, respectively. Cox proportional hazard analysis revealed that a short proximal landing zone and a high number of stent grafts used were independent risk factors for early and late endoleak formation. Late endoleak formation was an independent predictor of survival.

CONCLUSIONS

Endovascular stent graft placement in atherosclerotic aneurysms involving the descending aorta has satisfactory durability. An extensive landing zone is a prerequisite of early and late success. Further clinical investigations are warranted to evaluate long-term durability of this attractive treatment modality.

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.

Access for Endovascular Aneurysm Repair

Despite advancement in stent-graft technology, access-related problems continue to occur during endovascular repair of aortic aneurysms. Various techniques have been adopted to overcome difficult access situations, however. To survey these developments in arterial access, we performed a systematic literature review from 1994 through 2005 to identify relevant articles pertaining to endovascular access techniques and complications. Excessive iliac tortuosity, circumferential vessel wall calcification, significant occlusive disease, and small caliber vessels account for the majority of access problems, most of which are readily apparent with adequate baseline imaging. Even with careful preoperative assessment, however, some access problems may not be foreseen; nonetheless, the majority can be overcome using today's array of ancillary procedures, such as an iliac conduit, a brachiofemoral wire, or arterial reconstruction. Alternatively, other approach routes, such as the common carotid artery or direct aortic access, may be used to facilitate endovascular aneurysm repair.

Technical feasibility and biocompatibility of a newly designed separating stent-graft in the normal canine aorta

OBJECTIVE

The objectives of this study were to assess the performance of a newly designed separating stent-graft system with respect to the technical feasibility of transfemoral deployment, the maintenance of vessel patency, and stent deformity due to mechanical defects; and to evaluate its in vivo healing characteristics, including thrombus formation, and endothelial covering of the stent-graft when placed in the normal aorta of a canine model.

CONCLUSION

The newly designed separating stent-graft allowed accurate deployment without migration. This animal study also provided an opportunity to examine the healing process associated with an ultrathin polyester fabric nitinol stent and showed predictable healing characteristics in the normal thoracic aorta in this canine model.

Endovascular repair of abdominal aneurysms: Is this the method of choice?

BACKGROUND

The prevalence of abdominal aneurysms has increased due to the aging population, and endovascular repair has developed into an effective, less invasive treatment.

METHODS/RESULTS

Two recent cases at the University of Texas-Houston highlight a variety of clinical considerations that allow informed decision-making regarding optimal treatment of abdominal aneurysms. A thorough discussion of recent data summarizes the current understanding and techniques regarding abdominal aortic aneurysm repair.

CONCLUSIONS

Endovascular repair of abdominal aortic aneurysms has emerged as a viable and a safe alternative to surgical repair and may offer important advantages in a majority of patients with this disease.

INvestigation of STEnt grafts in patients with type B Aortic Dissection: design of the INSTEAD trial--a prospective, multicenter, European randomized trial

PURPOSE

This study describes the design of an ongoing randomized trial initiated to compare the 2-year outcome of uncomplicated type B aortic dissection when treated by endovascular implantation of a Medtronic Talent stent graft adjunctive to best medical treatment versus best medical treatment alone.

METHODS

Patients older than 18 years with type B aortic dissection as diagnosed by computed tomography or magnetic resonance angiography are randomized to either a thoracic aortic endoprosthesis and antihypertensive treatment, called "stent grafting," or a tailored antihypertensive treatment, called "medical treatment." Only patients in a clinically stable condition and without spontaneous thrombosis of the false lumen after 14 days of the index dissection are considered eligible for study inclusion.

RESULTS

Primary outcome measure is all-cause mortality. Secondary outcome variables include conversion to stent and/or surgery, induced thrombosis of the false lumen, cardiovascular morbidity, aortic expansion (>5 mm/y of maximum diameter including true and false lumina), quality of life, and length of intensive care unit and hospital stay. The study design calls for 136 patients to be randomized and monitored for 24 months.

CONCLUSIONS

The INSTEAD trial is the first randomized trial investigating the role of endoluminal treatment of uncomplicated type B aortic dissection. By the end of December 2004, 125 patients were randomized, accounting for 92% of the target. Final results of the INSTEAD trial should be available in 2006.

Multislice CT virtual angioscopy of the abdomen

BACKGROUND

Computed tomographic (CT) angiography represents an important clinical tool in the evaluation of vascular disorders. Virtual angioscopy can be reconstructed with volumetric CT data sets. We evaluated the feasibility and clinical value of this application in the assessment of abdominal vessels.

METHODS

Data sets of CT angiographic studies obtained with helical (n = 120) and multislice (n = 180) CT scanners were analyzed on a workstation for postprocessing. Vascular evaluation was done on conventional enhanced axial images, three-dimensional reconstructions, and virtual angioscopic images.

RESULTS

We made 123 studies in patients without aortic disease. Of the patients evaluated for stent-graft treatment, 63 showed normal patency, seven had partial thrombosis of the stent-graft, five showed total occlusion of the stent-graft, and 10 had leaks. From the 92 remaining CT studies, 63 vascular aneurysms and nine dissections were diagnosed.

CONCLUSION

The current technology produces high-quality virtual angioscopic images. Although axial and multiplanar views are usually adequate for detecting a vascular disorder, virtual angioscopic views better define anatomic details.

Superiority of endovascular grafts compared to bare metal stents with transstent coil embolization for endovascular abdominal aortic aneurysm repair in patients at high risk for surgery

We sought to determine the effectiveness of uncovered stents with aneurysm transstent coil embolization compared with endografts for percutaneous abdominal aortic aneurysm (AAA) repair. Thirty-six patients with AAA considered inoperable underwent endovascular repair using the Ancure bifurcated endograft or overlapping uncovered stents with transstent coil embolization. Procedural success, outcomes, serial aneurysm size, aneurysm blood flow, and growth ratios were compared between groups. One patient in each group died due to the procedure and two patients in the endograft cohort required acute surgical repair. After 2.0 +/- 0.8 years of follow-up, three patients required endograft placement, four surgical repair, three had AAA rupture, with two AAA-related deaths in the uncovered stent group. No late deaths or surgical conversion occurred in the endograft group. The primary AAA flow exclusion and aneurysm expansion rate and growth were superior in the endograft group and during follow-up. In high-risk patients with AAA, the use of endografts was superior compared to uncovered stents with transstent coil embolization for endovascular repair.

Assessment of Automatic Vessel Tracking Techniques in Preoperative Planning of Transluminal Aortic Stent Graft Implantation

OBJECTIVE

To evaluate automatic vessel tracking techniques in the course of preoperative planning prior to transluminal aortic endograft implantation by comparing accuracy, reproducibility, and postprocessing time with source image and volume-rendered analysis methods.

METHODS

Multislice computed tomography datasets of 5 patients with abdominal aortic aneurysms were preoperatively examined, performing volumetric analysis of diameter and position of renal artery orifices, aneurysmal neck, maximal aneurysmal extension, aortic bifurcation, and iliac arteries and bifurcation. Analysis was realized by utilizing transverse datasets, volume rendering, and automated vessel tracking strategies (MxView, Philips, Best, The Netherlands). Measurement techniques were evaluated by 2 independent readers 3 times for each patient and measurement modality. Statistical analysis evaluated accuracy of the measurements and intra- and interobserver reliability. Postprocessing time was documented.

RESULTS

Using transverse source datasets, intraobserver reliability ranged from 0.49 to 0.58. Intraobserver reliability improved to 0.7 to 0.98 when volume-rendered datasets were evaluated. Interobserver variability for transverse and volume-rendered datasets ranged from 0.49 to 0.76 and 0.70 to 0.96, respectively. Automated vessel tracking datasets did not demonstrate any intra- or interobserver variability. Based on transverse datasets, the length and diameter of iliac arteries and location and diameter of the aneurysmal neck were measured as statistically different in all cases in contrast to volume rendering and automated segmentation techniques. Postprocessing time consumption for measurements based on transverse, volume-rendered, and automated tracking segmentation datasets averaged 3.32 minutes, 25.43 minutes, and 2.24 minutes, respectively.

CONCLUSIONS

Preoperative measurements improve significantly if datasets are evaluated based on volume-rendering techniques. This time-consuming procedure can be shortened, while further reducing observer variability, with automatic segmentation techniques.

Essential techniques for intraoperative composite endograft (CEG) formation in the treatment of abdominal aortic aneurysm

The development of an ideal aortic stent graft continues to progress. New devices and techniques are expanding the use of endovascular repair in the treatment of abdominal aortic aneurysms (AAA). We present data with intraoperative composite endograft (CEG) techniques evaluating immediate and short-term compatibility of components and patients outcome. Twenty-five of 66 patients (38%) received intraoperative CEGs for AAA treatment. A total of 50 components were used to treat type I endoleaks, prevent graft limb kinking or treat associated iliac aneurysm. Nine of the components were used to manage type I proximal endoleaks. Forty-one components were used at the iliac limb for distal type I endoleak, hostile iliac anatomy, or graft limb support or to treat an associated iliac aneurysm. Two patients were left with a type I endoleaks at the iliac attachment site on completion of graft placement. With a mean follow-up of 11 months. Two of 25 patients had a type II endoleak at 6 months. One patient had type I endoleak at 1 year follow-up. CEGs are essential to treat endoleaks with a high technical success rate and expand the indications for treating infrarenal AAA. The component's short-term compatibility makes this method of stent graft placement safe.

Detection of endoleaks after endovascular repair of abdominal aortic aneurysm: value of unenhanced and delayed helical CT acquisitions

PURPOSE

To assess unenhanced and delayed phase computed tomographic (CT) images combined with arterial phase images for detecting endoleaks after endovascular treatment for abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

CT scans were retrospectively evaluated for the presence of endoleaks after endovascular treatment of AAAs in 33 patients with endoleak (positive group) and 40 patients without evidence of endoleak or aneurysm enlargement (negative group). All patients underwent unenhanced and biphasic contrast material-enhanced CT. The CT scans were reviewed in the following combinations: (a) arterial phase and unenhanced scans (uniphasic/unenhanced set), (b) arterial and delayed phase scans only (biphasic set), and (c) arterial and delayed phase scans with unenhanced scans (complete set). Each set was reviewed by two radiologists blinded to the diagnosis of endoleak. Findings were recorded as positive, negative, or indeterminate for endoleak.

RESULTS

Within the positive group, endoleaks were diagnosed with the uniphasic/unenhanced, biphasic, and complete image sets in 30 (91%), 32 (97%), and 33 (100%) patients, respectively. With the uniphasic/unenhanced set, three (9%) endoleaks (seen only on delayed phase images) were missed. With the biphasic set, one (3%) endoleak was interpreted as indeterminate. Within the negative group, uniphasic/unenhanced, biphasic, and complete image sets were negative for endoleaks in 100%, 80%, and 100% of patients, respectively. With the biphasic set, results were indeterminate in 20% of cases.

CONCLUSION

A delayed CT acquisition enables detection of additional endoleaks, while an unenhanced acquisition helps eliminate indeterminate results. Thus, both acquisitions contribute to accurate diagnosis of endoleaks when combined with an arterial phase acquisition.

Early and late functional outcome assessments following endovascular and open aneurysm repair

PURPOSE

To compare early and late functional outcomes, as well as survival and recovery, following endovascular or open repair of abdominal aortic aneurysm (AAA).

METHODS

Between 1996 and 2000, 294 patients underwent AAA repair (141 open and 153 endovascular); 57 patients from each group had 12-month follow-up for functional outcome assessment. Recovery was measured as hospital length of stay, skilled nursing requirement, and hospital readmission within 1 year to determine cumulative hospital utilization. Early (<6 months) functional outcomes were measured by activity level and convalescence days following surgery. Late (>6 months) functional outcomes were measured as ambulation, independent living, and employment status pre- and postoperatively.

RESULTS

Operative mortality for open repair was 5 (3.5%) compared to 1 (0.6%) after an endovascular procedure (p<0.05). The endovascular group had a shorter hospital stay (2.8+/-2.8 versus 8.3+/-4.5 days) and fewer skilled nursing requirements (0% versus 26%; p<0.001). Cumulative hospital utilization over 12 months was 3.8 days for endovascular patients and 13.8 days for open repair (p<0.001). Recovery time was 99.3+/-84.1 days (range 14-365) in conventionally treated patients and 32.1+/-43.5 days (range 7-180) in the stent-graft group (p<0.001). At 6 months, 43 (75%) open and 54 (95%) endovascular patients had full recovery (p<0.01). Activity levels decreased in 13 (23%) open and 3 (5%) endovascular patients after surgery (p<0.01). There were no differences in ambulation, independent living, or employment status before and after treatment.

CONCLUSIONS

Periprocedural survival following aneurysm repair is improved with endovascular grafting compared to open surgery, and recovery is more rapid, with a 78% reduction in total hospital days. Early functional outcomes are markedly improved with endovascular repair, while there is no difference in late functional outcomes between the procedures.

Successful treatment of aortic endograft thrombosis with rheolytic thrombectomy

PURPOSE

To report the benefits of rheolytic thrombectomy for treating aortic endograft thrombosis.

METHODS

Of 40 patients who received the Ancure bifurcated endograft to treat abdominal aortic aneurysm (AAA) during a 9-month period, 6 (15%) patients (6 men; mean age 62.6 years, range 53-77) developed thrombosis of the endograft at an average of 9 weeks (range 1-20 months). Five patients were taking aspirin, and 3 were on warfarin therapy for atrial fibrillation. Immediately after angiography, rheolytic thrombectomy was used to remove the thrombus, followed by adjunctive procedures to treat the underlying pathology.

RESULTS

Causes were kinking or extrinsic compression of the graft limb in 5 cases and thrombosis of the surgical closure site in a common femoral artery. Mechanical thrombectomy was successful in restoring circulation in all cases; thrombolysis was used in 1. All 6 patients had additional stents placed in the graft limbs, re-establishing patency. There was no mortality or recurrent thrombosis in a follow-up that has extended to 26 months, but 1 patient required additional stenting for subsequent focal kinking of a graft limb above the previously implanted stent.

CONCLUSIONS

Rheolytic thrombectomy can safely and effectively treat endograft thrombosis after endovascular AAA repair. Additional thrombolytic agents, angioplasty, and stenting may be needed to correct the underlying causes of the thrombosis. Prophylactic stenting of iliac limbs at the time of implantation in patients with complex anatomy may prevent thrombosis of unsupported bifurcated endografts.

Endovascular repair reduces early and late morbidity compared to open surgery for abdominal aortic aneurysm

PURPOSE

To compare systemic complications between standard surgery and endovascular repair of abdominal aortic aneurysms (AAA) for both primary and late secondary procedures.

METHODS

At a single center between July 1993 and May 2000, 297 patients (255 men; mean age 73.4 +/- 8.1 years, range 50-93) were treated with open surgical repair; beginning in 1996, 200 (166 men; mean age 73.6 +/- 8.0 years, range 45-96) patients were treated with the AneuRx stent-graft. In a comparison of the cohorts, which were similar in terms of age, gender, and aneurysm diameter, the main outcomes were early major systemic morbidity following the primary procedure to treat the aneurysm and late (>30 days) organ system morbidity for any secondary procedures.

RESULTS

Mean length of follow-up for open patients was 20.1 +/- 17.1 months (range 1-150) compared to 12.4 +/- 9.6 months (range 1-60) after endovascular repair (p<0.05). There were 36 (12.1%) systemic complications after the primary open surgery and 15 (7.5%) after endovascular repair (p=NS). There were 43 (14.5%) combined primary and secondary morbidities in the open surgery group versus 15 (7.5%) for patients undergoing endovascular repair (p<0.01). The need for invasive procedures to treat these primary and secondary systemic complications was 4 times greater in the open group (17, 5.7%) than in endograft patients (3, 1.5%) (p<0.05). After secondary procedures (32 in the open group and 30 in the endovascular patients) for graft-related complications, there were 7 (21.9%) adverse events in the open group versus none (0%) for endograft patients (p<0.01). Hospital lengths of stay following both primary and secondary procedures were lower for the endograft patients (p<0.01 and p<0.001, respectively).

CONCLUSIONS

Endovascular stent-graft repair compared to open surgery has reduced the early and late morbidity by half. Complications that require invasive or secondary surgical procedures and hospitalization are reduced with endovascular repair.

Covered stent-graft repair of the brachiocephalic arteries: technical note

OBJECTIVE

The use of a covered stent-graft to repair disruptions of the cervical carotid and vertebral arteries is described. This device maintains vessel patency while effectively excluding pseudoaneurysms, arteriovenous fistulae, and other breaches in the integrity of the arterial wall.

METHODS

Patient 1 bled from a large rent in the proximal common carotid artery as a result of tumor invasion. Patient 2 developed a vertebral arteriovenous fistula after a stab injury to the neck. Patient 3 developed cerebral infarction and an enlarging pseudoaneurysm of the internal carotid artery, also after a stab wound to the neck.

RESULTS

All three patients were treated with the Wallgraft endoprosthesis (Boston Scientific, Watertown, MA). In each case, the vessel wall defect was repaired while antegrade flow through the artery was preserved or restored. No neurological complications occurred as a result of stent-graft deployment.

CONCLUSION

Covered stent-grafts offer an alternative to endovascular occlusion of the parent vessel, thereby expanding the therapeutic options for patients with extracranial cerebrovascular disease. These three cases highlight the usefulness and versatility of these devices for endoluminal reconstruction of the brachiocephalic vasculature.

Endovascular placement of a nitinol-ePTFE stent-graft for abdominal aortic aneurysms: initial and midterm results

PURPOSE

Because first-generation stent-grafts did not meet initial expectations, a recently designed nitinol-expanded polytetrafluoroethylene (ePTFE) stent-graft was tested for treatment of abdominal aortic aneurysms (AAAs) in a prospective clinical study. The primary study endpoints were technical success and safety.

MATERIALS AND METHODS

A nitinol-ePTFE self-expandable stent-graft (Excluder) was used to treat 72 patients with AAAs. The median follow-up period was 21.5 months +/- 13 (range, 1-46 mo).

RESULTS

Primary technical success in accurate placement of the device was achieved in 70 of 72 patients (97%). Complete exclusion of the aneurysm from arterial flow was achieved in 57 of 72 patients (79.2%). Three type I leaks were observed during implantation and were immediately corrected with a proximal cuff prosthesis in two patients. Fourteen of 72 patients (19.4%) had a type II leak. Major complications were observed in three patients (4.1%), including one death in the early postinterventional period (one of 72, 1.4%). At 3 months, aneurysms were excluded in 70 of 71 patients (98.6%), and at 12 months, aneurysms were occluded in 29 of 30 patients (96.7%). The maximum diameter of the aneurysm decreased from 55 mm +/- 11 (median +/- SD) before intervention to 53 mm +/- 13 at 6 and 12 months. None of the patients showed aneurysm growth.

CONCLUSION

This newly designed stent-graft proved to be effective and safe for treatment of AAAs.

Influence of blood-pool contrast media on MR imaging and flow measurements in the presence of pulmonary arterial stents in swine

PURPOSE

To compare the effects of various stents on magnetic resonance (MR) imaging flow volume measurements and to determine the value of a blood-pool MR imaging contrast medium in assessment of vascular stents.

MATERIALS AND METHODS

In 11 pigs, six nitinol stents (Memotherm), four platinum stents (NuMed), and one elgiloy stent (Wallstent) were placed in the main pulmonary artery under x-ray fluoroscopic guidance. MR imaging was performed 3 months after stent placement before and after injection of NC100150 contrast medium. Blood flow volumes were assessed with velocity-encoded cine MR imaging through and next to the stent. The signal-to-noise ratio and width of susceptibility artifacts of the stents also were determined. Measurements were analyzed with the paired Student t test and Bland-Altman test, where appropriate.

RESULTS

Blood flow volumes measured through the nitinol and platinum stents disclosed no significant difference between velocity-encoded cine MR imaging measurements through and next to the stent. On cine MR images, small susceptibility artifacts were observed around the nitinol and platinum stents. Signal-to-noise ratio in the stent lumen was reduced in nitinol and platinum stents when compared with that next to the stent. The elgiloy stent produced severe susceptibility artifacts, making measurement of flow volumes impossible. NC100150 injection caused no significant effect on flow volume measurements. It improved the signal-to-noise ratio of the pulmonary arterial lumen outside and, to a lesser extent, inside the stent.

CONCLUSION

Assessment of morphology and flow volumes through nitinol and platinum stents is feasible with MR imaging. Blood-pool contrast media provide persistent signal enhancement in the pulmonary artery and, to a lesser extent, in the lumina of nitinol and platinum stents.

Endovascular aneurysm repair: Magnetic resonance monitoring of histological organization processes in the excluded aneurysm

BACKGROUND

The purpose of the present study was to systematically analyze the histopathologic organization processes in excluded aneurysms after endovascular stenting and to develop a noninvasive monitoring method for these processes using MRI.

METHODS AND RESULTS

In 36 mongrel dogs, autologous aortic aneurysms were created. Endovascular treatment was performed using covered stents. Follow-up was after 1 week, 6 weeks, and 6 months. MRI was performed with T2-weighted turbo-spin-echo sequences and T1-weighted spin-echo sequences and was repeated after contrast bolus with gadolinium. Histopathologic findings were correlated to signal intensities (SIs) of MRI images. SIs of distinct areas were analyzed and related to the SI of the reference tissue (SI ratio). The histological organization process was gradated in the following 4 classes: class 0, detritus without organization; classes I and II, connective tissue proliferation with increasing fiber synthesis; and class III, dense fibrous connective tissue. The SI ratios of T2-weighted images were significantly reduced from 4.76 in detritus (0) to 1.70 in dense fibrous connective tissue (III) as a function of histopathologic classes. SI ratios of T1-weighted images were reduced from 1.84 (0) to 1.12 (III). Contrast bolus with gadolinium-DTPA showed no change of SI ratio in detritus (0.99) but an increase from 1.12 (I) to 1.70 (III) as organization increased.

CONCLUSIONS

The histological organization of excluded aneurysms can be monitored by MRI. Progressive organization is indicated by decreasing SIs in T2- and an increasing signal increase in T1-weighted images after gadolinium bolus.

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.