Recognizing the impact of the decision making by the dialysis access surgeon on the successful placement of autogenous arteriovenous hemodialysis access, the Society for Vascular Surgery assembled a ...multispecialty panel to develop practice guidelines in arteriovenous access placement and maintenance with the aim of maximizing the percentage and functionality of autogenous arteriovenous accesses that are placed. The Society commissioned the Knowledge and Encounter Research Unit of the Mayo Clinic College of Medicine, Rochester, Minnesota, to systematically review the available evidence in three main areas provided by the panel: timing of referral to access surgeons, type of access placed, and effectiveness of surveillance. The panel then formulated practice guidelines in seven areas: timing of referral to the access surgeon, operative strategies to maximize the placement of autogenous arteriovenous accesses, first choice for the autogenous access, choice of arteriovenous access when a patient is not a suitable candidate for a forearm autogenous access, the role of monitoring and surveillance in arteriovenous access management, conversion of a prosthetic arteriovenous access to a secondary autogenous arteriovenous access, and management of the nonfunctional or failed arteriovenous access. For each of the guidelines, the panel stated the recommendation or suggestion, discussed the evidence or opinion upon which the recommendation or suggestion was made, detailed the values and preferences that influenced the group's decision in formulating the relevant guideline, and discussed technical remarks related to the particular guideline. In addition, detailed information is provided on various configurations of autogenous and prosthetic accesses and technical tips related to their placement.
The Society for Vascular Surgery pursued development of clinical practice guidelines for the management of the left subclavian artery with thoracic endovascular aortic repair (TEVAR). In formulating ...clinical practice guidelines, the society selected a panel of experts and conducted a systematic review and meta-analysis of the literature. They used the grading of recommendations assessment, development, and evaluation (GRADE) method to develop and present their recommendations. The overall quality of evidence was very low. The committee issued three recommendations. Recommendation 1: In patients who need elective TEVAR where achievement of a proximal seal necessitates coverage of the left subclavian artery, we suggest routine preoperative revascularization, despite the very low-quality evidence (GRADE 2, level C). Recommendation 2: In selected patients who have an anatomy that compromises perfusion to critical organs, routine preoperative LSA revascularization is strongly recommended, despite the very low-quality evidence (GRADE 1, level C). Recommendation 3: In patients who need urgent TEVAR for life-threatening acute aortic syndromes where achievement of a proximal seal necessitates coverage of the left subclavian artery, we suggest that revascularization should be individualized and addressed expectantly on the basis of anatomy, urgency, and availability of surgical expertise (GRADE 2, level C).
Objective Increased use of continuous-flow left ventricular assist devices for long-term mechanical support necessitates a better understanding of hemodynamic changes in the native heart and the ...ascending aorta. By using patient-specific computational models, correlations of potentially adverse hemodynamic conditions with the orientation of the left ventricular assist device outflow graft and their relationship with aortic insufficiency and ischemic events were investigated. Methods Computed hemodynamic parameters, including wall shear stress, pressure in the ascending aorta, and dissipation of turbulent energy, were correlated with the orientation of the left ventricular assist device graft outflow in 5 patients (4 with the HeartMate II device Thoratec Corp, Pleasanton, Calif and 1 with the HeartWare Ventricular Assist Device HeartWare Inc, Framingham, Mass; 3 patients experienced moderate aortic insufficiency, and 2 patients experienced ischemic events). Hemodynamic conditions for aortic insufficiency and ischemic events were differentiated by linear discriminant analysis. Results Positive correlations between left ventricular assist device outflow graft orientation and wall shear stress, pressure, and turbulent energy dissipation in the ascending aorta were found ( R 2 > 0.68). Linear discriminant analysis indicated a relationship of the velocity magnitude of retrograde flow toward the aortic root with aortic insufficiency and of the turbulent energy and wall shear stress with ischemic events. Conclusions Computational fluid dynamic simulations using clinical image data indicate altered hemodynamic conditions after left ventricular assist device implantation. Consequently, the left ventricular assist device outflow graft should be placed so the jet of blood is aimed toward the lumen of the aortic arch to avoid turbulences that will increase wall shear stress and retrograde pressure of the aortic root. Further investigations are warranted to confirm these findings in a larger patient cohort.
Objectives Covered stents have been proposed as an endovascular option for recalcitrant cases of hemodialysis-related central venous occlusive disease (CVOD). This study evaluated the efficacy and ...durability of covered stents in treating CVOD to preserve a functional dialysis access circuit. Methods A retrospective review was performed of all patients with clinically significant CVOD who were treated by placement of covered stents from April 2007 to September 2010. Demographics, lesion locations and anatomic characteristics, stent graft, and access patency rates were determined. Complications, reinterventions, and factors influencing their outcomes were examined. Results In 25 patients (56% men; mean age, 57 ± 29 years) with CVOD, covered stents were used in 20 to treat symptomatic venous hypertension or in 5 at the time of access creation to enable functionality. The target lesion was accessed via the dialysis access site or the common femoral vein. The Viabahn endoprosthesis (W. L. Gore and Associates, Flagstaff, Ariz) was used in 24 patients (average size and length, 11 mm × 5 cm) and a 13-mm × 5-cm Fluency covered stent (Bard Peripheral Vascular, Tempe, Ariz) was implanted in 1 patient. Technical success was 100%, and resolution of arm edema occurred after covered stent deployment in symptomatic patients. Two postprocedural cases (8%) of thrombosis occurred, one within 30 days and another at 3 months. Both required percutaneous thrombectomy and percutaneous transluminal angioplasty (PTA). Three additional patients (12%) required PTA due to restenosis in one of the ends of the device. Covered stent primary patency (PP), assisted primary patency (APP), and secondary patency (SP) were 56%, 86%, and 100% at 12 months, respectively. Access patency rates at 12 months were 29%, 85%, and 94% for PP, APP, and SP, respectively, in patients that received a covered stent for access salvage; patency rates were 74%, 85%, and 94% for PP, APP, and SP, respectively, in patients in whom the access was created after the venous outflow restoration. Conclusions Placement of covered stents for hemodialysis-related CVOD is safe, effective in relieving symptoms, and enabled functionality of new dialysis access circuits. Further prospective and randomized studies are necessary to determine whether covered stents provide superior long-term results to those achieved with PTA and bare metal stents.
Abstract Objective Combining three-dimensional (3D) catheter control with electromagnetic (EM) tracking-based navigation significantly reduced fluoroscopy time and improved robotic catheter movement ...quality in a previous in vitro pilot study. The aim of this study was to expound on previous results and to expand the value of EM tracking with a novel feature, assisted navigation , allowing automatic catheter orientation and semiautomatic vessel cannulation. Methods Eighteen users navigated a robotic catheter in an aortic aneurysm phantom using an EM guidewire and a modified 9F robotic catheter with EM sensors at the tip of both leader and sheath. All users cannulated two targets, the left renal artery and posterior gate, using four visualization modes: (1) Standard fluoroscopy (control). (2) 2D biplane fluoroscopy showing real-time virtual catheter localization and orientation from EM tracking. (3) 2D biplane fluoroscopy with novel EM assisted navigation allowing the user to define the target vessel. The robotic catheter orients itself automatically toward the target; the user then only needs to advance the guidewire following this predefined optimized path to catheterize the vessel. Then, while advancing the catheter over the wire, the assisted navigation automatically modifies catheter bending and rotation in order to ensure smooth progression, avoiding loss of wire access. (4) Virtual 3D representation of the phantom showing real-time virtual catheter localization and orientation. Standard fluoroscopy was always available; cannulation and fluoroscopy times were noted for every mode and target cannulation. Quality of catheter movement was assessed by measuring the number of submovements of the catheter using the 3D coordinates of the EM sensors. A t -test was used to compare the standard fluoroscopy mode against EM tracking modes. Results EM tracking significantly reduced the mean fluoroscopy time ( P < .001) and the number of submovements ( P < .02) for both cannulation tasks. For the posterior gate, mean cannulation time was also significantly reduced when using EM tracking ( P < .001). The use of novel EM assisted navigation feature (mode 3) showed further reduced cannulation time for the posterior gate ( P = .002) and improved quality of catheter movement for the left renal artery cannulation ( P = .021). Conclusions These results confirmed the findings of a prior study that highlighted the value of combining 3D robotic catheter control and 3D navigation to improve safety and efficiency of endovascular procedures. The novel EM assisted navigation feature augments the robotic master/slave concept with automated catheter orientation toward the target and shows promising results in reducing procedure time and improving catheter motion quality.
Objective Current interventional techniques rely heavily on operator familiarity with catheters and wires and on physician skills in effectively navigating through and managing target lesions. A ...novel robotic technology allows endovascular specialists to remotely control catheter tip deflection and advancement and to coordinate manipulation of currently available wires. The aim of this study was to successfully demonstrate feasibility and safety of navigation to and treatment of iliac and femoral artery lesions using Hansen Medical's vascular control catheter (VCC). Methods A total of 20 limbs were included in this analysis for a first-in-man trial of the VCC and vascular catheter control system. The local Institutional Review Board approved the trial, and all patients included had symptomatic femoropopliteal occlusive disease. Preoperative imaging was available on all patients. Target lesions in the contralateral superficial femoral artery ranged from mild stenosis to chronic total occlusions (TransAtlantic Inter-Society A through D). Exclusion criteria included previously treated iliac and femoral lesions in the symptomatic leg and a body mass index >35. The operators comprised three experienced interventionalists (two vascular surgeons and an interventional radiologist) and a novice (cardiac surgeon). The primary end point of the study was to demonstrate successful cannulation of the target vessel (ie, navigation to the lesion with wire and catheter) with the Hansen VCC, with no device-related serious adverse events. Secondary end points were to assess the ability to treat lesions using the flexible catheter defined by successful insertion of a guidewire, angiography of the target vessel, delivery of balloon, and/or stent. Procedure times and radiation delivered were analyzed for the group and by operator, and t -test was performed to determine statistical significance. Complications were assessed by clinical examination and ultrasound. Results Lesions were successfully and safely cannulated in all limbs treated. The VCC performed as designed in all cases. All interventionalists, regardless of experience, navigated the VCC with ease. However, statistically significant differences in navigation time and radiation per case were observed between the experienced and inexperienced interventionalists. There were no access site complications (hematoma, thrombosis, pseudoaneurysm) as evaluated by ultrasound. Conclusions This initial experience in flexible robotics demonstrates that this technology is both efficacious and safe in the arterial tree. Although robotics provides superior maneuverability compared with current techniques, endovascular experience is crucial to taking full advantage of the extra capabilities. Valuable future considerations will include off-the-wall (center lumen) navigation with three-dimensional imaging.
Computational fluid dynamics, which uses numeric methods and algorithms for the simulation of blood flow by solving the Navier-Stokes equations on computational meshes, is enhancing the understanding ...of disease progression in type III aortic dissections. To illustrate this, we examined the changes in patient-derived geometries of aortic dissections, which showed progressive false lumen aneurysmal dilatation (26% diameter increase) during follow-up. Total pressure was decreased by 29% during systole and by 34% during retrograde flow. At the site of the highest false lumen dilatation, the temporal average of total pressure decreased from 45 to 22 Pa, and maximal average wall shear stress decreased from 0.9 to 0.4 Pa. These first results in the study of disease progression of type III DeBakey aortic dissection with computational fluid dynamics are encouraging.
Background While aggressive endoluminal therapy for superficial femoral artery (SFA) occlusive disease is commonplace, the implications of runoff on long-term outcomes of these interventions in ...patients with rest pain and tissue loss is unclear. Runoff is known to negatively effect graft patency. The aim of this study is to examine the impact of distal runoff on long-term outcomes of SFA interventions for critical ischemia. Methods A prospective database of patients undergoing endovascular treatment of the SFA between 1986 and 2007 was queried. Patients with Rutherford symptom classification 4, 5, and 6 were selected. Patients with concomitant tibial interventions were excluded. Pre-operative angiograms were reviewed in all cases to assess distal popliteal and tibial runoff and were scored according to modified Society of Vascular Surgery criteria for both vessels such that a higher score implies worse runoff (minimum 1 and maximum 19). Three runoff score groups were identified: <5 (Good), 5-10 (Compromised), and >10 (Poor). Kaplan-Meier survival analyses were performed to assess time-dependent outcomes. Multivariate and Factor analyses were performed. Results Three hundred six limbs in 241 patients (57% male, mean age 68 years) underwent endovascular treatment for critical ischemia (44% rest pain and 56% tissue loss.) Technical success was 96% with 61% SFA undergoing angioplasty, 37% SFA primary stenting and 2% SFA an atherectomy. Overall mortality was 1% and overall morbidity was 16% at 90 days after the procedure. At 5 years, vessels with compromised and poor runoff had significantly worse cumulative patency (82 ± 9%, 56 ± 4%, and 52 ± 7% for Good, Compromised, and Poor runoffs, respectively, mean ± standard error of the mean SEM). Freedom from recurrent symptoms (65 ± 8%, 39 ± 9%, and 18 ± 9% for Good, Compromised, and Poor runoffs, respectively) and limb salvage (65 ± 5%, 41 ± 4%, and 20 ± 6% for Good, Compromised, and Poor runoffs, respectively) were incrementally curtailed by worsening runoff with significant decreases as runoff category deteriorated. Conclusions In patients presenting with rest pain and tissue loss who are treated with SFA percutaneous interventions, patency is negatively affected by compromised and poor runoffs in keeping with the bypass literature. More importantly, freedom from recurrent symptoms and limb salvage are incrementally curtailed as runoff scores worsen. These findings are consistent with the bypass literature.
Abstract Objective Three-dimensional image fusion of preoperative computed tomography (CT) angiography with fluoroscopy using intraoperative noncontrast cone-beam CT (CBCT) has been shown to improve ...endovascular procedures by reducing procedure length, radiation dose, and contrast media volume. However, patients with a contraindication to CT angiography (renal insufficiency, iodinated contrast allergy) may not benefit from this image fusion technique. The primary objective of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) and fluoroscopy image fusion using noncontrast CBCT as a guidance tool during complex endovascular aortic procedures, especially in patients with renal insufficiency. Methods All endovascular aortic procedures done under MRA image fusion guidance at a single-center were retrospectively reviewed. The patients had moderate to severe renal insufficiency and underwent diagnostic contrast-enhanced magnetic resonance imaging after gadolinium or ferumoxytol injection. Relevant vascular landmarks electronically marked in MRA images were overlaid on real-time two-dimensional fluoroscopy for image guidance, after image fusion with noncontrast intraoperative CBCT. Technical success, time for image registration, procedure time, fluoroscopy time, number of digital subtraction angiography (DSA) acquisitions before stent deployment or vessel catheterization, and renal function before and after the procedure were recorded. The image fusion accuracy was qualitatively evaluated on a binary scale by three physicians after review of image data showing virtual landmarks from MRA on fluoroscopy. Results Between November 2012 and March 2016, 10 patients underwent endovascular procedures for aortoiliac aneurysmal disease or aortic dissection using MRA image fusion guidance. All procedures were technically successful. A paired t -test analysis showed no difference between preimaging and postoperative renal function ( P = .6). The mean time required for MRA-CBCT image fusion was 4:09 ± 01:31 min:sec. Total fluoroscopy time was 20.1 ± 6.9 minutes. Five of 10 patients (50%) underwent stent graft deployment without any predeployment DSA acquisition. Three of six vessels (50%) were cannulated under image fusion guidance without any precannulation DSA runs, and the remaining vessels were cannulated after one planning DSA acquisition. Qualitative evaluation showed 14 of 22 virtual landmarks (63.6%) from MRA overlaid on fluoroscopy were completely accurate, without the need for adjustment. Five of eight incorrect virtual landmarks (iliac and visceral arteries) resulted from vessel deformation caused by endovascular devices. Conclusions Ferumoxytol or gadolinium-enhanced MRA imaging and image fusion with fluoroscopy using noncontrast CBCT is feasible and allows patients with renal insufficiency to benefit from optimal guidance during complex endovascular aortic procedures, while preserving their residual renal function.
Objective Thoracic endograft placement has become an acceptable treatment alternative to open repair of the thoracic aorta. Cerebral embolization when manipulating the aortic arch during cardiac ...catheterization is well described, but the influence of thoracic endovascular aortic repair (TEVAR) on this event remains poorly studied. Our aim was to quantify the number of microembolic signals (MES) detected by transcranial Doppler (TCD) during different stages of TEVAR and correlate them with landing zones, subclavian revascularization, and postoperative morbidity and mortality. Methods TCD was used to monitor 20 patients during TEVAR for the treatment of thoracic aortic aneurysms (TAAs) in 17 (85%) patients, followed by three (15%) with chronic type B aortic dissection and one (5%) Crawford type I thoracoabdominal aortic aneurysm (TAAA). Imaging and medical parameters were entered into a combined database. TCD signals were recorded digitally for the entire case. MES, velocities, and pulsatility index values were entered into a combined database. Results The total number of MES calculated for the diagnostic phase before TEVAR placement and during the treatment phase for all cases combined was 1081 and 1141, respectively. The highest MES counts were generated by the pigtail catheter placement during the diagnostic phase and by device placement during the treatment phase. Embolic count to right/left sides was equal overall. In the diagnostic phase, an average of nine MES were seen right/left, whereas during the treatment phase, 45 and 43 MES were seen, respectively, for right/left. A significant association was found between the total number of MES and postoperative stroke, transient ischemic attack ( P = .0055), and death ( P = .0053). Conclusions TCD can detect microemboli during TEVAR and is able to identify the procedural aspects most associated with cerebral microemboli.
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