Primary Endovascular Repair of Juxtarenal Aneurysms with Fenestrated Endovascular Grafting

Brazilian Society for Angiology and Vascular Surgery guidelines on abdominal aortic aneurysm

The Brazilian Society of Angiology and Vascular Surgery, through the Guidelines Project, presents new Abdominal Aortic Aneurysm Guidelines, on the subject of care for abdominal aortic aneurysm patients. Its development prioritized descriptive guidelines, using the EMBASE, LILACS, and PubMed databases. References include randomized controlled trials, systematic reviews, meta-analyses, and cohort studies. Quality of evidence was evaluated by a pair of coordinators, aided by the RoB 2 Cochrane tool and the Newcastle Ottawa Scale forms. The subjects include juxtarenal aneurysms, infected aneurysms, and new therapeutic techniques, especially endovascular procedures. The current version of the guidelines include important recommendations for the primary topics involving diagnosis, treatment, and follow-up for abdominal aortic aneurysm patients, providing an objective guide for medical practice, based on scientific evidence and widely available throughout Brazil.

A Single Center Review of a Total Transfemoral Approach to Upper Extremity Access in Branched and Fenestrated Physician Modified Endografts

BACKGROUND

Aortic aneurysms are normally treated by an endovascular approach. Due to the lack of devices and increasing experience, there is a growing number of complex aneurysms undergoing repair by physician modified endografts (PMEGs). Previously, our practice was to target visceral vessels exclusively through upper extremity access. We have since then shifted to an all transfemoral approach when possible. This study aims to show the operative benefits of transfemoral only approaches.

METHODS

Patients who underwent a PMEG at a tertiary center between 2015 and 2020 were included. Patients were stratified into 2 groups based on branched vessel approach-transfemoral only versus axillary or composite (axillary and femoral). Forty-one patients had a pararenal or type IV thoracoabdominal aortic aneurysm (TAAA) and 15 patients had more complex TAAA. Primary outcomes were operative time, radiation exposure, fluoroscopy time, contrast, and blood loss. Secondary outcomes were 30-day mortality and major adverse events. Linear regression models were used to evaluate the association between approach type and the main outcomes.

RESULTS

Fifty-six patients were included with 48% (n = 27) in the transfemoral group and 52% (n = 29) in the axillary/composite group. Baseline characteristics were similar between the groups. Intraoperative outcomes revealed significant increase in the average operative time (418 vs. 246 min, P < 0.001), in radiation exposure (2,755 vs. 1,740 mGy, P = 0.03), in fluoroscopy time (108 vs. 74 min, P = 0.01) and in blood loss (579 vs. 202 cc, P = 0.002) in the axillary/composite group compared to the transfemoral group. There was no significant difference in 30-day mortality or major adverse events including stroke.

CONCLUSIONS

This study shows a transfemoral approach to complex endovascular aortic aneurysm repair as opposed to axillary/composite approach has decreased operative time, radiation exposure, and fluoroscopy time and no significant differences in 30-day mortality or major adverse events. When treating complex aneurysms, improving efficiency is important to minimize morbidity to patients and operators.

Initial experience with the Terumo aortic Treo device for fenestrated endovascular aneurysm repair

OBJECTIVE

The Terumo aortic (TA) Treo device (Terumo, Somerset, NJ) is an endograft with unique features that lends itself to fenestrated endovascular aneurysm repair (FEVAR), including a low device profile, a wide amplitude stent design, and an increased interstent distance. We have described our initial experience with the Treo device for FEVAR to treat short neck and juxtarenal abdominal aortic aneurysms.

METHODS

As part of an ongoing physician-sponsored investigational device exemption clinical trial (ClinicalTrials.gov identifier, NCT01538056), subjects were prospectively enrolled and underwent elective FEVAR using a variety of devices. Demographic and procedural details were collected. The data from subjects treated specifically with the Treo device from November 3, 2016 to May 2, 2019 were collected and analyzed.

RESULTS

Of a cohort of 161 patients who had undergone elective FEVAR, 46 had been treated with the TA Treo device. Most patients were men (70%), with a mean age of 75 years and high rates of hypertension (74%), hyperlipidemia (83%), coronary artery disease (33%), and chronic obstructive pulmonary disease (33%). The mean aneurysm size was 66 mm, the mean preoperative infrarenal neck length was 5 mm, and the mean final seal zone length was 45 mm. The average hospital and intensive care unit lengths of stay were 2.4 and 1.5 days, respectively. A total of 129 fenestrations were created for 44 superior mesenteric and 85 renal arteries (2.8 fenestrations per patient). Technical success, defined as successful implantation of the device with all target vessels preserved, was 98% (45 of 46), with only one renal artery not successfully preserved. The mean follow-up period was 598 days. During the study period, 18 endoleaks were detected (17 type II and 1 type III), with one patient with a type III endoleak requiring reintervention. Three subjects had died within 30 days, one of intracranial hemorrhage, one of respiratory failure, and one of ischemic colitis. The graft modification times for the TA Treo were significantly shorter (43 minutes) than those for other commercially available devices (Cook Zenith, 55 minutes; Medtronic Endurant, 54 minutes; P < .0001).

CONCLUSIONS

Our institution has reported exclusive worldwide experience using the TA Treo device for FEVAR. This device provides for a highly efficient and technically successful procedure for most patients. The procedural and fluoroscopy times were low even in the setting of high complexity. The technical success rates and simplification of the FEVAR procedure have made this approach a preferred technique for most patients at our institution.

The Italian Multicentre Registry of Fenestrated Anaconda™ Endografts for Complex Abdominal Aortic Aneurysms Repair

OBJECTIVE

The aim was to describe the outcomes of the Anaconda™ Fenestrated endograft Italian Registry for complex aortic aneurysms (AAAs), unsuitable for standard endovascular aneurysm repair (EVAR).

METHODS

Between 2012 and 2018 patients with a proximal neck unsuitable for standard EVAR, treated with the fenestrated Anaconda™ endograft, were prospectively enrolled in a dedicated database. Endpoints were peri-operative technical success (TS) and evaluation of type Ia/b or 3 endoleaks (T1/3 EL), target visceral vessel (TVV) occlusion, re-interventions, and AAA related mortality at 30 days, six months, and later follow up.

RESULTS

One hundred twenty seven patients (74 ± 7 years, American Society Anesthesiology (ASA) II/III/IV: 12/85/30) were included in the study in 49 Italian Vascular Surgery Units (83 juxta/para-renal AAA, 13 type IV thoraco-abdominal AAA, 16 T1aEL post EVAR, and 15 short neck AAA). Configurations with one, two, three, and four fenestrations were used in 5, 56, 39, and 27 cases, respectively, for a total of 342 visceral vessels. One hundred and eight (85%) bifurcated and 19 (15%) tube endografts were implanted. In 35% (44/127) of cases the endograft was repositioned during the procedure, and 37% (128/342) of TVV were cannulated from brachial access. TS was 87% (111/127): five T1EL, six T3EL (between fenestration and vessel stent), and six loss of visceral vessels (one patient with a Type Ia EL had also a TVV loss) occurred. Thirty day mortality was 4% (5/127). Two of the five T1EL resolved spontaneously at 30 days. The overall median follow up was 21 ± 16 months; one T1EL (5%) occurred at six months and one T3EL (4%) at the three year follow up. Another two (3%) TVV occlusions occurred at six months and five (3%) at three years. The re-intervention rate at the 30 days, six months, and three year follow up was 5%, 7%, and 18 ± 5%, respectively.

CONCLUSION

The fenestrated Anaconda™ endograft is effective in the treatment of complex AAA. Some structure properties, such as the re-positionability and the possibility of cannulation from above, are specific characteristics helpful for the treatment of some complex anatomies.

Imaging Obtained Up To 12 Months Preoperatively Is Adequate for Planning Fenestrated/Branched Endovascular Aortic Aneurysm Repair

OBJECTIVES

Patients referred for fenestrated/branched endovascular aortic repair (F/BEVAR) often present with a previous computed tomography angiogram (CTA), but it is unknown how recent the CTA must be to ensure accurate F/BEVAR planning. We sought to determine whether anatomic planning parameters change significantly between a CTA used for F/BEVAR planning and a CTA obtained 6 to 12 months prior.

METHODS

Two blinded observers reviewed preoperative CTAs from 21 patients who underwent F/BEVAR. Each patient had a "recent" scan obtained 0 to 6 months before F/BEVAR planning and a "prior" scan obtained 6 to 12 months before the "recent" CTA. Standard measurements included (1) target vessel separation distances, (2) target vessel origin clock position, and (3) proximal F/BEVAR device diameter. Clinically significant differences for target vessel separation distance, target vessel origin clock position, and proximal F/BEVAR device diameter were predefined as >5 mm, >30 minutes, and >4 mm, respectively. Differences between "recent"/"prior" CTA scans were examined by paired t test.

RESULTS

Mean time interval between paired "recent"/"prior" CTAs was 8.0 months (standard deviation: ±1.7). Mean difference in paired "recent"/"prior" target vessel distance (relative to celiac artery [CA]) was 2.6 mm for the superior mesenteric artery (SMA), 2.5 mm for the right renal artery (RRA), and 3.3 mm for the left renal artery (LRA). Of the 21 paired "recent"/"prior" CTAs, clinically significant differences were observed in 2, 4, and 2 patients for SMA, RRA, and LRA target vessel distance, respectively. Target vessel clock position (SMA reference at 12:00) varied by 12 minutes for the CA, 13 minutes for the RRA, and 15 minutes for the LRA. One paired "recent"/"prior" CTA was found to have a clinically significant difference for the LRA. No clinically significant differences were observed for proximal device diameter.

CONCLUSIONS

In patients who underwent successful F/BEVAR, measurement comparisons between CTAs obtained up to 1 year prior were minor and unlikely to yield clinically significant changes to F/BEVAR design.

The role of selective stenting for superior mesenteric artery scallops during fenestrated endovascular aneurysm repair

OBJECTIVE

Stenting of small fenestrations of the Zenith fenestrated endograft (ZFEN; Cook Medical, Bloomington, Ind) is necessary during fenestrated endovascular aneurysm repair (FEVAR) of complex abdominal aortic aneurysms to avoid malalignment. However, stenting of superior mesenteric artery (SMA) scallops of ZFEN devices is optional according to the instructions for use. The objective of this study was to assess the early and midterm outcomes of selective use of stents in SMA scallops of ZFEN during FEVAR procedures.

METHODS

This study is a single-institution retrospective review of prospectively enrolled patients treated at the University of North Carolina at Chapel Hill between July 2010 and August 2014. Only patients with SMA scallops were included for analysis. We compared results between patients grouped as stented or unstented SMA scallops. The scallops were stented when one or more of the following criteria were present: misalignment of scallop determined by balloon testing intraoperatively; configuration consisting of an SMA scallop and a single renal fenestration or stent; and pre-existing stenosis in the vessel adjacent to the graft scallop. The study was approved by the local Institutional Review Board. Primary outcomes addressed were mortality, vessel patency, early and late complications, and reintervention rates. Baseline characteristics of the patients and procedure data were also described.

RESULTS

During the 48-month study period, 61 patients were treated for complex abdominal aortic aneurysms at the University of North Carolina with a mean age of 73 years, and 74.3% of patients were male. Thirty-nine of 61 patients (63.9%) had a device design with an SMA scallop and were included for analysis. Eleven of 39 patients (28%) had the SMA primarily stented and 28 (72%) were unstented. There was only one death (2.5%) during the 30-day postoperative period, with 100% technical success and branch patency. In the unstented group, there were three SMA complications during follow-up, two requiring reintervention; however, there were no associated deaths. Among the stented group, there was one branch-related complication that occurred during the procedure but no stent stenosis or occlusion during the long-term follow-up. During the mean follow-up period of 21.7 months, no SMA stent thrombosis occurred. There was no statistical difference in outcomes between groups.

CONCLUSIONS

Single-wide SMA scallops of ZFEN during FEVAR procedures may be selectively stented using specific criteria and rigorous follow-up, without compromising the safety and efficacy of the SMA.

Fenestrated and Branched Stent Grafting in Complex Aneurysmatic Aortic Disease: A Single-Center Early Experience

BACKGROUND

The aim of this study is to present our early experience and highlight the technical difficulties associated with the use of fenestrated and branched stent grafts to treat patients with juxtarenal abdominal aortic aneurysm (AAA), pararenal AAA, and thoracoabdominal aortic aneurysms (TAAAs).

METHODS

A prospectively held database maintained at our department was queried for patients who have undergone branched and fenestrated stent grafting for AAA or TAAA treatment. Indication for repair, comorbidity precluding open repair, technical challenges associated with the repair, as well as operative mortality, morbidity, and reintervention rate were evaluated.

RESULTS

A total of 8 patients underwent repair with a fenestrated or branched stent graft. All patients had aneurysmal degeneration of the juxtarenal aorta, pararenal aorta, and thoracoabdominal aorta not suitable to standard endovascular techniques. Two patients had a prior aortic repair, a failed migrated stent graft, and an old surgical tube graft after an open repair. One patient had a type III TAAA and 1 patient had a postdissection TAAA type I. For all patients, target vessel success rate was 96.4% (27/28) and mean hospital stay was 6.0 days (range 3-21). Thirty-day and 1-year mortality were 0%. Mean follow-up was 23 months (range 7-45). Two endoleaks occurred, 1 type III and 1 type II, which were treated endovascularly. No death or major complication occurred during follow-up.

CONCLUSIONS

Fenestrated and branched endovascular stent grafts can be used to repair juxtarenal AAA, pararenal AAA, and TAAA in patients with significant comorbidities. However, several technical challenges have to be overcome due to the unique complex aortic pathology of each patient.

Fenestrated stent grafts for the treatment of complex aortic aneurysm disease: A mature treatment paradigm

The introduction of fenestrated stent grafts (SGs) to treat abdominal aortic aneurysms (AAAs) with short proximal necks began in 1999. Nowadays, the whole visceral aorta can be treated totally by endovascular means. The established use of fenestrated devices to treat complex AAAs as a first-line management option has been previously reported. An up-to-date evaluation of the literature was performed including all types of publications regarding the use of fenestrated technology to repair complex AAAs. Fenestrated repair is now an established alternative to hybrid/chimney/snorkel repairs. However, specific criteria and prerequisites are required for the use and improvement of this method. Multiple device morphologies have been used incorporating the visceral arteries in various combinations. This modular strategy connects different devices (bridging covered stents and bifurcated SGs) with the aortic main body, thus excluding the aneurysm from the circulation. Precise deployment of the fenestrated SG is mandatory for successful visceral vessel revascularization. Accurate SG sizing and customization, a high level of technical skill, and facilities with modern imaging techniques including 3D road mapping and dedicated hybrid rooms are required. Most experience has been with the custom-made Zenith Cook platform, although off-the-shelf devices have been recently implanted. More complex repairs have been performed over the last few years, but device complexity has also increased. Perioperative, mid-term, and a few recently reported long-term results are encouraging. Secondary interventions remain the main problem, similar to that observed after traditional endovascular abdominal aortic aneurysm repair (EVAR).

The Current State of Fenestrated and Branched Devices for Abdominal Aortic Aneurysm Repair

Endovascular abdominal aortic aneurysm repair (EVAR) provides an attractive alternative to traditional open techniques. Endovascular repair is frequently limited by aortic aneurysm neck angulation, the absence of an adequate infrarenal neck, and the need for internal iliac preservation. Several devices have been created to incorporate visceral artery segments as well as preserve the internal iliac artery, thus broadening the patient population suited for endovascular repair. This article will provide a review of the current literature regarding fenestrated devices, branch devices, off-the-shelf devices, and physician-modified devices. It will also highlight the iliac branch stent grafts currently on trial for internal iliac artery preservation. Data thus far have suggested that these devices will be both a safe and effective option for anatomically challenging abdominal aortic aneurysms.

Impact of Renal Artery Angulation on Procedure Efficiency During Fenestrated and Snorkel/Chimney Endovascular Aneurysm Repair

Purpose: To determine the impact of renal artery angulation on time to successful renal artery cannulation and procedure efficiency during fenestrated and snorkel/chimney endovascular aneurysm repair (EVAR). Methods: The imaging and procedure logs of 77 patients (mean age 74.2 years; 63 men) who underwent complex EVAR (24 fenestrated, 53 snorkel/chimney) from 2009 to 2013 were reviewed. Renal artery angulation was measured on preoperative computed tomographic angiography scans. Time to renal artery cannulation was retrieved from the EVAR procedure logs and compared to preoperative renal artery angulation and other metrics of procedure efficiency (eg, procedure time, fluoroscopy time, blood loss, etc). In all, 111 renal arteries were available for renal artery angulation measurement (39 fenestrated, 72 snorkel/chimney); 22 renal cannulations were inappropriate for the comparative analyses due to concomitant visceral artery stenting (n=15), combined procedures (n=6), or unsuccessful cannulation (n=1). Results: For patients undergoing fenestrated EVAR, mean renal artery angulation was -28°±21° (range +37° to -60°), not significantly different (p=0.66) from patients receiving snorkel/chimney grafts (mean -30°±19°, range +22° to -65°). Comparative analysis using median renal artery angulation (−30° for both groups) demonstrated that renal artery cannulation during fenestrated EVAR was performed significantly faster in arteries with less downward (≥ −30°) angulation (16.0 vs 32.8 minutes, p=0.04), whereas cannulation in snorkel/chimneys was faster in arteries with greater downward (< −30°) angulation (10.9 vs 17.3 minutes, p=0.05). Fenestrated EVAR cases involving less downward (≥ −30°) renal artery angulation were also associated with shorter overall procedure time (187.7 vs 246.2 minutes, p=0.01) and decreased fluoroscopy time (70.3 vs 98.2 minutes, p=0.04). Immediate renal function decline, procedural complications, and postoperative issues were not associated with renal artery angulation. Conclusion: Procedural efficiency may be optimized by considering renal artery angulation as one of several objective variables used in the selection of an appropriate endovascular strategy. The fenestrated approach is more efficient with less downward angulation to the renal arteries, while the snorkel/chimney strategy is facilitated by more downward renal artery angulation.

Fenestrated and chimney endografts for juxtarenal aneurysms: early and midterm results

AIM

To assess the early and short-term outcome of fenestrated and chimney grafting for juxtarenal aortic aneurysms.

MATERIAL AND METHODS

A prospective vascular registry of 28 patients who had undergone elective primary endovascular repair for abdominal aortic aneurysm between December 2007 and August 2011 with infrarenal neck anatomy unacceptable for conventional endovascular repair. Fenestrated endografts were designed based on reconstructed computed tomography (CT) data by the authors. Off-the-shelf grafts and stents were used for chimney cases. Patients were followed up until 31 May 2012.

RESULTS

A total of 21 (75%) patients were treated with fenestrated endografts, while 7 (25%) received chimney grafts. The mean aneurysm diameter was 65 mm (standard deviation = 7 mm) and the median neck length 2.5 mm (range: 0-10 mm). Altogether, 63 (mean = 2.3/patient) visceral arteries were incorporated (42 renal, 21 superior mesenteric arteries). The overall primary technical success rate was 93% (one type I and one type III endoleak). The mean follow-up was 22 months (standard deviation: 14 months). The primary type III endoleak resolved spontaneously with thrombosis of the target vessel, while the patient with primary type I endoleak died of acute myocardial infarction 3 weeks after the procedure. Two late endoleaks developed: one type II endoleak without aneurysm sac growth remains under surveillance, while in another patient, multiple attempts to treat type I endoleak proved unsuccessful and the patient later died of gastrointestinal bleeding. A total of 4 (14%) patients so far required additional procedures. Two patients died within 30 days of the device implantation and another six during the follow-up. No rupture occurred. The cumulative survival for patients with fenestrated endografts was 85% at 1 year and for those treated with chimney technique 57%.

CONCLUSIONS

The treatment of juxtarenal aortic aneurysms seems to be feasible by exploiting various endovascular techniques. Even with a low volume of cases, good immediate and short-term results can be achieved, especially with fenestrated endografts.

Fenestrated endovascular repair of abdominal aortic aneurysms is associated with increased morbidity but comparable mortality with infrarenal endovascular aneurysm repair

OBJECTIVE

A recent prospective study found that fenestrated endovascular abdominal aortic aneurysm (AAA) repair (FEVAR) was safe and effective in appropriately selected patients at experienced centers. As this new technology is disseminated to the community, it will be important to understand how this technology compares with standard endovascular AAA repair (EVAR). The goal of this study was to compare the outcomes of FEVAR vs EVAR of AAAs.

METHODS

The American College of Surgeons-National Surgical Quality Improvement Program database from 2005 to 2012 was queried for AAAs (International Classification of Diseases, Ninth Revision code 441.4). Patients were stratified according to procedure (FEVAR vs EVAR). A bivariate analysis was done to assess preoperative and intraoperative risk factors for postoperative outcomes. Thirty-day postoperative mortality and complication rates were described for each procedure type. Multivariable logistic regression was performed to assess the association between the type of procedure and the risk of postoperative complications.

RESULTS

A total of 458 patients underwent FEVAR and 19,060 patients underwent EVAR for AAA. Patients undergoing FEVAR were older (P = .02) and less likely to have a bleeding disorder (P = .046). Otherwise, the incidence of comorbidities in both groups was similar. FEVAR was associated with increased median operative time (156 vs 137 minutes; P < .001), and average postoperative length of stay (3.3 vs 2.8 days; P = .03). There was a statistically significant increase in overall complications (23.6% vs 14.3%; P < .001) and postoperative transfusions (15.3% vs 6.1%, P < .001) and trends toward increased cardiac complications (2.2% vs 1.3%; P = .09) and the need for dialysis (1.5% vs 0.8%; P = .08) in the FEVAR group. Mortality (2.4% vs 1.5%; P = .12) was not statistically different. On multivariable analysis, FEVAR remained independently associated with the need for postoperative transfusions when operative time was <75th percentile (adjusted odds ratio, 1.72; 95% confidence interval, 1.09-2.72; P = .02) as well as when operative time was >75th percentile for respective procedures (adjusted odds ratio, 5.33; 95% confidence interval, 3.55-8.00; P < .001).

CONCLUSIONS

Patients undergoing FEVAR are more likely than patients undergoing EVAR to receive blood transfusions postoperatively and are more likely to sustain postoperative complications. Although mortality was similar, trends toward increased cardiac and renal complications may suggest the need for judicious dissemination of this new technology. Future research with larger number of FEVAR cases will be necessary to determine if these associations remain.

Repair of type I endoleak by chimney technique after endovascular abdominal aortic aneurysm repair

Endovascular aneurysm repair is a minimally invasive, durable and effective alternative to open surgery for treatment of abdominal aortic aneurysms (AAA). However, in patients who do not have an adequate sealing zone, open surgical repair is required, which may increase mortality and morbidity. An alternative treatment in patients with challenging anatomy is the so-called "chimney graft" technique. Here, we describe a case using the chimney graft technique for treatment of juxtarenal type I endoleak followed by a previous conventional stent graft insertion to the AAA with good results.

Outcomes after abdominal aortic aneurysm repair requiring a suprarenal cross-clamp

OBJECTIVE

The objective of this study was to analyze the early and late outcomes of patients who require a suprarenal aortic cross-clamp during elective open repair of an abdominal aortic aneurysm (AAA).

METHODS

Patients from 1998 to 2012 who required a suprarenal aortic cross-clamp during elective open AAA repair were reviewed. Data abstracted included demographics and comorbidities; preoperative, perioperative, and late renal function; late interventions related to AAA repair; and late mortality. A decrease in renal function was defined as a >30% decline in estimated glomerular filtration rate (eGFR) compared with the preoperative value. Primary outcomes included renal function, intervention-free survival, and overall survival.

RESULTS

During the study period, 211 patients underwent open elective or urgent AAA repair; 69 required a suprarenal cross-clamp. The mean age was 71 years, and 80% were men. The mean preoperative creatinine concentration was 1.2 mg/dL, and the mean preoperative eGFR was 66 mL/min/1.73 m2. Location of the aortic cross-clamp was suprarenal (37), supramesenteric (21), and supraceliac (11). Perioperatively, 21 patients (30%) experienced a significant decrease in eGFR; four patients required hemodialysis. Six patients had full recovery of renal function by discharge. Perioperative morbidity and mortality were 35% and 4%, respectively. At a mean follow-up of 3 years, seven patients had an eGFR significantly less than the preoperative value. Late interventions related to the AAA repair were required in eight patients. Indications included wound complication (3), anastomotic aneurysm (2), incisional hernia (1), anastomotic graft stenosis (1), and proximal aortic dilation (1). Overall 5-year intervention-free survival was 62% and overall survival 77%. Intervention-free survival was enhanced by antiplatelet use (P = .04), whereas overall survival was decreased by chronic obstructive pulmonary disease (P = .003) and perioperative pneumonia (P = .001).

CONCLUSIONS

More than a quarter of patients requiring a suprarenal cross-clamp during open AAA repair experience renal dysfunction. Late graft-related complications are few, with preoperative and perioperative pulmonary function negatively affecting overall patient survival.

Intra-operative 2-D ultrasound and dynamic 3-D aortic model registration for magnetic navigation of transcatheter aortic valve implantation

We propose a navigation system for transcatheter aortic valve implantation that employs a magnetic tracking system (MTS) along with a dynamic aortic model and intra-operative ultrasound (US) images. This work is motivated by the desire of our cardiology and cardiac surgical colleagues to minimize or eliminate the use of radiation in the interventional suite or operating room. The dynamic 3-D aortic model is constructed from a preoperative 4-D computed tomography dataset that is animated in synchrony with the real time electrocardiograph input of patient, and then preoperative planning is performed to determine the target position of the aortic valve prosthesis. The contours of the aortic root are extracted automatically from short axis US images in real-time for registering the 2-D intra-operative US image to the preoperative dynamic aortic model. The augmented MTS guides the interventionist during positioning and deployment of the aortic valve prosthesis to the target. The results of the aortic root segmentation algorithm demonstrate an error of 0.92±0.85 mm with a computational time of 36.13±6.26 ms. The navigation approach was validated in porcine studies, yielding fiducial localization errors, target registration errors, deployment distance, and tilting errors of 3.02±0.39 mm, 3.31±1.55 mm, 3.23±0.94 mm, and 5.85±3.06(°) , respectively.

An augmented magnetic navigation system for Transcatheter Aortic Valve Implantation

This research proposes an augmented magnetic navigation system for Transcatheter Aortic Valve Implantation (TAVI) employing a magnetic tracking system (MTS) combined with a dynamic aortic model and intra-operative ultrasound (US) images. The dynamic 3D aortic model is constructed based on the preoperative 4D computed tomography (CT), which is animated according to the real time electrocardiograph (ECG) input of patient. And a preoperative planning is performed to determine the target position of the aortic valve prosthesis. The temporal alignment is performed to synchronize the ECG signals, intra-operative US image and tracking information. Afterwards, with the assistance of synchronized ECG signals, the contour of aortic root automatic extracted from short axis US image is registered to the dynamic aortic model by a feature based registration intra-operatively. Then the augmented MTS guides the interventionist to confidently position and deploy the aortic valve prosthesis to target. The system was validated by animal studies on three porcine subjects, the deployment and tilting errors of which are 3.17 ± 0.91 mm and 7.40 ± 2.89° respectively.

Endovascular treatment of infrarenal abdominal aortic aneurysm with short and angulated neck in high-risk patient

Endovascular treatment of abdominal aortic aneurysms (AAA) is an established alternative to open repair. However lifelong surveillance is still required to monitor endograft function and signal the need for secondary interventions (Hobo and Buth 2006). Aortic morphology, especially related to the proximal neck, often complicates the procedure or increases the risk for late device-related complications (Hobo et al. 2007 and Chisci et al. 2009). The definition of a short and angulated neck is based on length (<15 mm), and angulation (>60°) (Hobo et al. 2007 and Chisci et al. 2009). A challenging neck also offers difficulties during open repairs (OR), necessitating extensive dissection with juxta- or suprarenal aortic cross-clamping. Patients with extensive aneurysmal disease typically have more comorbidities and may not tolerate extensive surgical trauma (Sarac et al. 2002). It is, therefore, unclear whether aneurysms with a challenging proximal neck should be offered EVAR or OR (Cox et al. 2006, Choke et al. 2006, Robbins et al. 2005, Sternbergh III et al. 2002, Dillavou et al. 2003, and Greenberg et al. 2003). In our case the insertion of a thoracic endograft followed by the placement of a bifurcated aortic endograft for the treatment of a very short and severely angulated neck proved to be feasible offering acceptable duration of aneurysm exclusion. This adds up to our armamentarium in the treatment of high-risk patients, and it should be considered in emergency cases when the fenestrated and branched endografts are not available.

Respiration-induced deformations of the superior mesenteric and renal arteries in patients with abdominal aortic aneurysms

PURPOSE

To quantify respiration-induced deformations of the superior mesenteric artery (SMA), left renal artery (LRA), and right renal artery (RRA) in patients with small abdominal aortic aneurysms (AAAs).

MATERIALS AND METHODS

Sixteen men with AAAs (age 73 y ± 7) were imaged with contrast-enhanced magnetic resonance angiography during inspiratory and expiratory breath-holds. Centerline paths of the aorta and visceral arteries were acquired by geometric modeling and segmentation techniques. Vessel translations and changes in branching angle and curvature resulting from respiration were computed from centerline paths.

RESULTS

With expiration, the SMA, LRA, and RRA bifurcation points translated superiorly by 12.4 mm ± 9.5, 14.5 mm ± 8.8, and 12.7 mm ± 6.4 (P < .001), and posteriorly by 2.2 mm ± 2.7, 4.9 mm ± 4.2, and 5.6 mm ± 3.9 (P < .05), respectively, and the SMA translated rightward by 3.9 mm ± 4.9 (P < .01). With expiration, the SMA, LRA, and RRA angled upward by 9.7° ± 6.4, 7.5° ± 7.8, and 4.9° ± 5.3, respectively (P < .005). With expiration, mean curvature increased by 0.02 mm(-1) ± 0.01, 0.01 mm(-1) ± 0.01, and 0.01 mm(-1) ± 0.01 in the SMA, LRA, and RRA, respectively (P < .05). For inspiration and expiration, RRA curvature was greater than in other vessels (P < .025).

CONCLUSIONS

With expiration, the SMA, LRA, and RRA translated superiorly and posteriorly as a result of diaphragmatic motion, inducing upward angling of vessel branches and increased curvature. In addition, the SMA exhibited rightward translation with expiration. The RRA was significantly more tortuous, but deformed less than the other vessels during respiration.

Respiratory-induced 3D deformations of the renal arteries quantified with geometric modeling during inspiration and expiration breath-holds of magnetic resonance angiography

PURPOSE

To quantify renal artery deformation due to respiration using magnetic resonance (MR) image-based geometric analysis.

MATERIALS AND METHODS

Five males were imaged with contrast-enhanced MR angiography during inspiratory and expiratory breath-holds. From 3D models of the abdominal aorta, left and right renal arteries (LRA and RRA), we quantified branching angle, curvature, peak curve angle, axial length, and locations of branch points.

RESULTS

With expiration, maximum curvature changes were 0.054 ± 0.025 mm(-1) (P < 0.01), and curve angle at the most proximal curvature peak increased by 8.0 ± 4.5° (P < 0.05) in the LRA. Changes in maximum curvature and curve angles were not significant in the RRA. The first renal bifurcation point translated superiorly and posteriorly by 9.7 ± 3.6 mm (P < 0.005) and 3.5 ± 2.1 mm (P < 0.05), respectively, in the LRA, and 10.8 ± 6.1 mm (P < 0.05) and 3.6 ± 2.5 mm (P < 0.05), respectively, in the RRA. Changes in branching angle, axial length, and renal ostia locations were not significant.

CONCLUSION

The LRA and RRA deformed and translated significantly. Greater deformation of the LRA as compared to the RRA may be due to asymmetric anatomy and mechanical support by the inferior vena cava. The presented methodology can extend to quantification of deformation of diseased and stented arteries to help renal artery implant development.

A pilot study on magnetic navigation for transcatheter aortic valve implantation using dynamic aortic model and US image guidance

PURPOSE

In this paper, we propose a pilot study for transcatheter aortic valve implantation guided by an augmented magnetic tracking system (MTS) with a dynamic aortic model and intra-operative ultrasound (US) images.

METHODS

The dynamic 3D aortic model is constructed from the preoperative 4D computed tomography, which is animated according to the real-time electrocardiograph (ECG) input of patient. Before the procedure, the US probe calibration is performed to map the US image coordinate to the tracked device coordinate. A temporal alignment is performed to synchronize the ECG signals, the intra-operative US image and the tracking information. Thereafter, with the assistance of synchronized ECG signals, the spatial registration is performed by using a feature-based registration. Then the augmented MTS guides the surgeon to confidently position and deploy the transcatheter aortic valve prosthesis to the target.

RESULTS

The approach was validated by US probe calibration evaluation and animal study. The US calibration accuracy achieved [Formula: see text], whereas in the animal study on three porcine subjects, fiducial, target, deployment distance and tilting errors reached [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively.

CONCLUSION

Our pilot study has revealed that the proposed approach is feasible and accurate for delivery and deployment of transcatheter aortic valve prosthesis.

Magnetic navigation for thoracic aortic stent-graft deployment using ultrasound image guidance

We propose a system for thoracic aortic stent-graft deployment that employs a magnetic tracking system (MTS) and intraoperative ultrasound (US). A preoperative plan is first performed using a general public utilities-accelerated cardiac modeling method to determine the target position of the stent-graft. During the surgery, an MTS is employed to track sensors embedded in the catheter, cannula, and the US probe, while a fiducial landmark based registration is used to map the patient's coordinate to the image coordinate. The surgical target is tracked in real time via a calibrated intraoperative US image. Under the guidance of the MTS integrated with the real-time US images, the stent-graft can be deployed to the target position without the use of ionizing radiation. This navigation approach was validated using both phantom and animal studies. In the phantom study, we demonstrate a US calibration accuracy of 1.5 ± 0.47 mm, and a deployment error of 1.4 ± 0.16 mm. In the animal study, we performed experiments on five porcine subjects and recorded fiducial, target, and deployment errors of 2.5 ± 0.32, 4.2 ± 0.78, and 2.43 ± 0.69 mm, respectively. These results demonstrate that delivery and deployment of thoracic stent-graft under MTS-guided navigation using US imaging is feasible and appropriate for clinical application.

Endovascular interventions for descending thoracic aortic aneurysms: The pivotal role of the clinical nurse in postoperative care

Descending thoracic aortic aneurysms (dTAA) comprise 40% of all aneurysms arising from the thoracic aorta. Because rupture of thoracic aneurysms is associated with a 94% mortality rate, timely detection, surveillance and treatment is imperative. Endovascular stent-graft repair of thoracic aneurysms was first performed in 1992 and has become an accepted treatment option for this condition in select candidates. There is an abundance of information for the care of patients after open surgical repair of dTAA. However, still relatively few written guidelines exist in the nursing literature for postoperative care and complications associated with endovascular stent-graft repair. The prevalence of aortic endografting, however, now makes it necessary for nurses to have a solid knowledge base in the operative procedure, complications and postoperative care for this patient population. Ideal candidates for aortic endografting undergo CTA or MRI preoperatively and fit a set of strict anatomic criteria to ensure proper delivery and fixation of the device. The early postoperative care focuses on minimizing pulmonary complications, paraplegia, renal failure and embolic complications such as stroke and limb ischemia through skilled nursing assessment and interventions. Late complications such as stent-graft migration, kinking, stent fracture and endoleak are often without symptoms, making it necessary for patients to be educated about these potential complications and to be encouraged to comply with lifelong follow up. This overview provides a sound cognitive framework for nurses practicing in a vascular surgery milieu.

"The chimney graft"-a simple technique for endovascular repair of complex juxtarenal abdominal aortic aneurysms in no-option patients

Endovascular aneurysm repair (EVAR) has developed as a less invasive alternative to open surgery for patients with abdominal aortic aneurysms. However, patients with very short infrarenal necks require complex surgical open repair, which is associated with increased mortality and morbidity. The risk of complex open repair may be prohibitive in high-risk patients. Thus, modifying the technique of EVAR may be required in such patients to successfully exclude aneurysms. An alternative that can be used in these patients is the so-called "chimney graft" technique. We report two cases where the chimney graft technique was used with good immediate results.

The role of robotic endovascular catheters in fenestrated stent grafting

OBJECTIVE

Fenestrated stent grafting has allowed the treatment of complex thoraco-abdominal aneurysm disease via a totally endovascular approach, but the procedure can be technically challenging and time consuming. We investigated whether this procedure may be enhanced by remotely steerable robotic endovascular catheters.

METHODS

A four-vessel fenestrated stent graft partially deployed within a computed tomography (CT)-reconstructed pulsatile thoraco-abdominal aneurysm silicon model was used. Fifteen operators were recruited to participate in the study and divided into three groups, based on their endovascular experience: group A (n = 4, 100-200 endovascular procedures, group B (n = 5, 200-300), and group C (n = 6, >300). All operators were asked to cannulate the renal and visceral vessels under fluoroscopic guidance, using conventional and robotic techniques. Quantitative (catheterization times and wire/catheter tip movements) and qualitative metrics (procedure-specific-rating scale [IC3ST]), which grades operators on catheter use, instrumentation, successful cannulation/catheterization, and overall performance were compared.

RESULTS

Median procedure time for cannulation of all four vessels was reduced using the robotic system (2.87 min, interquartile range [IQR; 2.20-3.90] versus 17.24 min [11.90-19.80]; P < .001) for each individual operator, regardless of the level of endovascular experience. The total number of wire/catheter movements taken to complete the task was also significantly reduced (38, IQR [29-57] versus 454 [283-687]; P < .001). There were significant differences in time and movement for cannulation of each individual vessel in the phantom. Robotic catheter operator radiation exposure was negligible as the robotic workstation is remote and away from the radiation source. Overall performance scores significantly improved using the robotic system, despite minimal operator exposure to this technology (IC3ST score 29/35, IQR [22.8-30.7] versus 19/35 [13-24.3]; P = .002). Each group of operators demonstrated an improvement in performance with robotic cannulation. For group A, median IC3ST score was 28/35, IQR (22-33) versus 15/35 (11-20); P = .04; for group B, 30/35 (27-31) versus 19/35 (18-24); P = .07; and for group C, 28.8/35 (28.5-29) versus 22/35 (16-24); P = .06. For groups B and C, these differences did not reach statistical significance.

CONCLUSION

Robotic catheterization of target vessels during this procedure is feasible and minimizes radiation exposure for the operator. Steerable robotic catheters with intuitive control may overcome some of the limitations of standard catheter technology, enhance target vessel cannulation, reduce instrumentation, and improve overall performance scores.