Jean Bismuth

Efficacy of covered stent placement for central venous occlusive disease in hemodialysis patients

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.

Computational study of haemodynamic effects of entry- and exit-tear coverage in a DeBakey type III aortic dissection: technical report.

OBJECTIVES Outcome prediction in DeBakey Type III aortic dissections (ADs) remains challenging. Large variations in AD morphology, physiology and treatment exist. Here, we investigate if computational fluid dynamics (CFD) can provide an initial understanding of pressure changes in an AD computational model when covering entry and exit tears and removing the intra-arterial septum (IS). DESIGN A computational mesh was constructed from magnetic resonance images from one patient (one entrance and one exit tear) and CFD simulations performed (scenario #1). Additional meshes were derived by virtually (1) covering the exit tear (false lumen (FL) thrombus progression) (scenario #2), (2) covering the entrance tear (thoracic endovascular treatment, TEVAR) (scenario #3) and (3) completely removing the IS (fenestration) (scenario #4). Changes in flow patterns and pressures were quantified relative to the initial mesh. RESULTS Systolic pressures increased for #2 (300 Pa increase) with largest inter-luminal differences distally (2500 Pa). In #3, false lumen pressure decreased essentially to zero. In #4, systolic pressure in combined lumen reduced from 2400 to 800 Pa. CONCLUSIONS CFD results from computational models of a DeBakey type III AD representing separate coverage of entrance and exit tears correlated with clinical experience. The reported results present a preliminary look at a complex clinical problem.

Hybrid thoracic endovascular aortic repair: Pushing the envelope

OBJECTIVE Thoracic endovascular aortic repair (TEVAR) can be limited by inadequate proximal and distal landing zones. Debranching or hybrid TEVAR has emerged as an important modality to expand landing zones and facilitate TEVAR. We report a single-center experience with hybrid TEVAR. METHODS We retrospectively reviewed all patients with thoracic aortic disease who received a TEVAR between February 2005 and October 2008. RESULTS Forty-two patients underwent a hybrid procedure (mean age 68 +/- 13 years; 55% men). All patients were denied open surgery due to preoperative comorbidities or low physiologic reserve; 62% had a history of coronary artery disease, 67% had chronic obstructive pulmonary disease, 61% had undergone prior aortic surgery, and 90% had an American Society of Anesthesiology score of 4 and above. The average Society for Vascular Surgery comorbidity score was 12 +/- 2 with a range of 9 to 14. Fifty-five percent of cases were symptomatic on presentation and 83% were done emergently. Seventy-six percent underwent debranching of the aortic arch, 17% of the visceral vessels, and 7% required both. Primary technical success was achieved in all cases and of these, 43% were staged. The 30-day mortality was 5%. Myocardial infarction developed in 5%, respiratory failure in 31%, cerebrovascular accident (stroke or transient ischemic attack) in 19%, and spinal cord ischemia with ensuant paraplegia occurred in 5% of patients. Fifty-eight percent of patients were discharged home, 11% required rehabilitation, and 29% were transferred to a skilled nursing facility. There was a significant association between visceral vessel debranching and both spinal cord ischemia (P = .004) and gastrointestinal complications (P = .005). On the other hand, there was no difference between staged and non-staged hybrid procedures. CONCLUSIONS Hybrid procedures can successfully extend the range of patients suitable for a subsequent TEVAR. These procedures are associated with higher complication rates than isolated infrarenal or thoracic endovascular repair, but given the medical and anatomical complexity of these patients, the current results are quite encouraging.

Percutaneous Placement of an Intra-Aortic Balloon Pump in the Left Axillary/Subclavian Position Provides Safe, Ambulatory Long-Term Support as Bridge to Heart Transplantation

OBJECTIVES This study evaluated the feasibility, tolerability, and efficacy of a strategy for percutaneous intra-aortic balloon pump (IABP) placement through the left axillary-subclavian artery to provide mechanical circulatory support in patients with end-stage heart failure as a bridge to heart transplantation. BACKGROUND The transfemoral approach to IABP placement is associated with major disadvantages, including the risk for infection and limitation of patient mobility in those requiring extended support. METHODS We developed a percutaneous technique for placing IABPs in the left axillary artery that permits upright sitting and ambulation. We performed a retrospective review of data from patients who had undergone left axillary IABP implantation between 2007 and 2012. RESULTS Fifty patients who received a left axillary IABP as a bridge to transplantation were identified, of whom 42 (84%) underwent heart or heart-multiorgan transplantation. Cumulative survival on IABP support was 92%, and post-transplant 90-day survival was 90%. Median duration of support was 18 days. Four of 50 patients (8%) died while on IABP support, and 3 (6%) received greater mechanical circulatory support. Four patients (8%) had clinically significant thromboembolic or bleeding events without long-term sequelae. The most common minor adverse event was IABP malposition, in 22 patients (44%). Prolonged IABP support in the heart-transplantation cohort was associated with significant improvements in mean pulmonary artery pressure and in creatinine and total bilirubin concentrations. CONCLUSIONS Percutaneous insertion of an IABP through the left axillary artery is a feasible and relatively well-tolerated strategy to bridge patients with end-stage heart failure to heart transplantation. This form of mechanical-device treatment permits upright sitting and ambulation in those requiring extended support.

E-selectin-targeting delivery of microRNAs by microparticles ameliorates endothelial inflammation and atherosclerosis.

E-selectin is a surface marker of endothelial cell (EC) inflammation, one of the hallmarks of atherogenesis. Thus, we tested the hypothesis that delivery of microRNA (miR)-146a and miR-181b with an E-selectin-targeting multistage vector (ESTA-MSV) to inflamed endothelium covering atherosclerotic plaques inhibits atherosclerosis. Cy5-conjugated miR-146a and miR-181b were packaged in polyethylene glycol-polyethyleneimine (PEG/PEI) nanoparticles and loaded into ESTA-MSV microparticles. Both miRs were downregulated in tumor necrosis factor (TNF)-α-treated ECs. Transfection of TNF-α-treated mouse aortas and cultured ECs with miRs was more efficient with ESTA-MSV than with the PEG/PEI. Likewise, miR-146a/-181b packaged in ESTA-MSV efficiently suppressed the chemokines, CCL2, CCL5, CCL8, and CXCL9, and monocyte adhesion to ECs. Complementary in vivo tests were conducted in male apolipoprotein E-deficient mice fed a Western diet and injected intravenously with the particles prepared as above biweekly for 12 weeks. Treatment with miRs packaged in ESTA-MSV but not in PEG/PEI reduced atherosclerotic plaque size. Concurrently, vascular inflammation markers, including macrophages in aortic root lesions and chemokine expression in aortic tissues were reduced while the vascular smooth muscle cells and collagen increased in plaques from ESTA-MSV/miRs-treated vs. vehicle-treated mice. Our data supported our hypothesis that ESTA-MSV microparticle-mediated delivery of miR-146a/-181b ameliorates endothelial inflammation and atherosclerosis.

A Computational Fluid Dynamics Study Pre- and Post-Stent Graft Placement in an Acute Type B Aortic Dissection

Purpose: To demonstrate the capability of computational fluid dynamics (CFD) for quantifying hemodynamic forces pretreatment/posttreatment in type B aortic dissection (TB-AD). Methods: From CFD simulations initialized with dynamic magnetic resonance image data, wall shear stress (WSS) and dynamic pressure (dynP) changes post endovascular treatment were quantified. Results: After 1 year follow-up, thoracic aortic segment was completely remodeled, and persistent, nonthrombosed false lumen in the abdominal aorta was noted. Pretreatment, large WSS (>5 Pa) and dynP (>80 Pa) occurred at entrance tear and a stenotic region in the true lumen (TL). Posttreatment, WSS was lower than 3.3 Pa and dynP was lower than 55 Pa in TL, except at proximal end of the stent graft and at reentrance tear. Two focal locations of high dynP existed within the stent graft. Conclusions: Computational fluid dynamics may provide quantitative assessment of hemodynamic wall forces in TB-AD potentially of interest for follow-up examinations.

Surgical management of hemodialysis-related central venous occlusive disease: A treatment algorithm

BACKGROUND Creation and preservation of dialysis access in patients with central venous occlusive disease (CVOD) is a complex problem. The surgical approach and decision-making process remains poorly defined. We evaluated our experience in the surgical management of hemodialysis-related CVOD. Surgical technique, demographics, complications, reinterventions, access function rates, and factors influencing morbidity and mortality were examined. METHODS From January 2006 to May 2010, we performed a total of 1,703 dialysis access-related procedures, 1,021 arteriovenous fistulas (AVFs), 335 arteriovenous grafts (AVGs), and 314 access revisions including endovascular salvage procedures. Seventeen patients (10 women [58%] with a mean age of 44 ± 27 years) with CVOD who were not suitable for peritoneal dialysis or kidney transplant underwent 20 complex vascular access procedures. The indications were need for access creation in 14 cases (70%) and preservation in the remaining 6 (30%). Polytetrafluoroethylene (PTFE) was used for all surgical bypass grafts (BPG). All patients had previously undergone multiple access surgeries and had failed percutaneous interventions for CVOD. RESULTS The surgical planning centered on finding venous outflow for an arteriovenous (AV) access; central venous reconstructions were necessary in 10 (50%) cases (seven [35%] in the thoracic central venous system and three [15%] in infradiaphragmatic vessels) and extracavitary venous BPG in two (10%) cases. Non-venous access options included axillary arterial-arterial chest wall BPG in five (25%) cases and brachial artery to right atrium BPG in three (15%). Technical success was achieved in all cases (100%). Mean follow-up was 14.1 months, both BPG and AV access patency rates were 66% at 6 months and overall average AV access function time was 9.2 months. Of these, 85% of patients were discharged home and following 19 (95%) cases they returned or improved their baseline functional status. One death occurred from multiorgan failure during the 30-day postoperative period. Four additional patients died within 3 years of the procedure secondary to nonsurgical-related comorbidities. CONCLUSION The need for complex vascular accesses will continue as the number of patients with end-stage renal disease increases. CVOD is an access surgical challenge and with this article we propose a decision-making algorithm.

Longitudinal computational fluid dynamics study of aneurysmal dilatation in a chronic DeBakey type III aortic dissection

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.

Prognostic factors and treatment outcome in mesenteric vein thrombosis

Background Mesenteric vein thrombosis (MVT) can result in intestinal ischemia and is associated with high morbidity and mortality due in part to its frequent delay in diagnosis. The purpose of this study was to evaluate clinical presentation, diagnostic evaluation, and treatment outcome of MVT. Methods Hospital records and clinical data of all patients treated for MVT were reviewed during a recent 14-year period. Clinical outcome and factors affecting survival were analyzed. Results A total of 68 patients were included in the study. Abdominal exploration was performed in 23 patients (34%), and second-look operation was necessary in 18 patients (26%). Three patients (4%) underwent unsuccessful operative mesenteric vein thrombectomy, whereas percutaneous transhepatic mesenteric thrombectomy was performed successfully in 3 patients (4%). The 30-day mortality rate was 20%. Forty-six of the 54 survivors were treated with long-term oral anticoagulation therapy. Actuarial survival at 2, 4, 6, and 10 years was 68%, 57%, 43%, and 22%, respectively. Risk factor analysis showed malignancy (P < .002), age >60 years (P < .005), cirrhosis (P < .02), symptom duration (P < .005), and bowel resection (P < .03) were associated with mortality. Logistic regression analysis showed age >60 years (odds ratio [OR], 3.64; P = .03), malignancy (OR, 3.88; P = .02), and prolonged symptom duration (OR, 5.62; P = .01) were independent predictors of mortality. Conclusions MVT is associated with significant mortality. Prompt diagnostic evaluation with computed tomography may reduce potential treatment delay. Underlying malignancy, advanced age, and prolonged symptom duration are predictive of poor outcome.

Transcranial Doppler findings during thoracic endovascular aortic repair

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.