Covered versus bare-metal stenting of the mesenteric arteries in patients with chronic mesenteric ischaemia (CoBaGI): a multicentre, patient-blinded and investigator-blinded, randomised controlled trial.

BACKGROUND: Mesenteric artery stenting with a bare-metal stent is the current treatment for atherosclerotic chronic mesenteric ischaemia. Long-term patency of bare-metal stents is unsatisfactory due to in-stent intimal hyperplasia. Use of covered stents might improve long-term patency. We aimed to compare the patency of covered stents and bare-metal stents in patients with chronic mesenteric ischaemia. METHODS: We conducted a multicentre, patient-blinded and investigator-blinded, randomised controlled trial including patients with chronic mesenteric ischaemia undergoing mesenteric artery stenting. Six centres in the Netherlands participated in this study, including two national chronic mesenteric ischaemia expert centres. Patients aged 18 years or older were eligible for inclusion when an endovascular mesenteric artery revascularisation was scheduled and a consensus diagnosis of chronic mesenteric ischaemia was made by a multidisciplinary team of gastroenterologists, interventional radiologists, and vascular surgeons. Exclusion criteria were stenosis length of 25 mm or greater, stenosis caused by median arcuate ligament syndrome or vasculitis, contraindication for CT angiography, or previous target vessel revascularisation. Digital 1:1 block randomisation with block sizes of four or six and stratification by inclusion centre was used to allocate patients to undergo stenting with bare-metal stents or covered stents at the start of the procedure. Patients, physicians performing follow-up, investigators, and radiologists were masked to treatment allocation. Interventionalists performing the procedure were not masked. The primary study outcome was the primary patency of covered stents and bare-metal stents at 24 months of follow-up, evaluated in the modified intention-to-treat population, in which stents with missing data for the outcome were excluded. Loss of primary patency was defined as the performance of a re-intervention to preserve patency, or 75% or greater luminal surface area reduction of the target vessel. CT angiography was performed at 6 months, 12 months, and 24 months post intervention to assess patency. The study is registered with ClinicalTrials.gov (NCT02428582) and is complete. FINDINGS: Between April 6, 2015, and March 11, 2019, 158 eligible patients underwent mesenteric artery stenting procedures, of whom 94 patients (with 128 stents) provided consent and were included in the study. 47 patients (62 stents) were assigned to the covered stents group (median age 69·0 years [IQR 63·0-76·5], 28 [60%] female) and 47 patients (66 stents) were assigned to the bare-metal stents group (median age 70·0 years [63·5-76·5], 33 [70%] female). At 24 months, the primary patency of covered stents (42 [81%] of 52 stents) was superior to that of bare-metal stents (26 [49%] of 53; odds ratio [OR] 4·4 [95% CI 1·8-10·5]; p<0·0001). A procedure-related adverse event occurred in 17 (36%) of 47 patients in the covered stents group versus nine (19%) of 47 in the bare-metal stent group (OR 2·4 [95% CI 0·9-6·3]; p=0·065). Most adverse events were related to the access site, including haematoma (five [11%] in the covered stents group vs six [13%] in the bare-metal stents group), pseudoaneurysm (five [11%] vs two [4%]), radial artery thrombosis (one [2%] vs none), and intravascular closure device (none vs one [2%]). Six (13%) patients in the covered stent group versus one (2%) in the bare-metal stent group had procedure-related adverse events not related to the access site, including stent luxation (three [6%] vs none), major bleeding (two (4%) vs none), mesenteric artery perforation (one [2%] vs one [2%]), mesenteric artery dissection (one [2%] vs one [2%]), and death (one [2%] vs none). INTERPRETATION: The findings of this trial support the use of covered stents for mesenteric artery stenting in patients with chronic mesenteric ischaemia. FUNDING: Atrium Maquet Getinge Group.

The Dutch chronic lower limb-threatening ischemia registry (THRILLER): A study protocol for popliteal and infrapopliteal endovascular interventions.

INTRODUCTION: Chronic limb-threatening ischemia (CLTI) is the end stage of peripheral arterial disease (PAD) and is associated with high amputation rates, mortality and disease-related health care costs. In infrapopliteal arterial disease (IPAD), endovascular revascularization should be considered for the majority of anatomical and clinical subgroups of CLTI. However, a gap of high-quality evidence exists in this field. The aim of the Dutch Chronic Lower Limb-Threatening Ischemia Registry (THRILLER) is to collect real world data on popliteal and infrapopliteal endovascular interventions. METHODS: THRILLER is a clinician-driven, prospective, multicenter, observational registry including all consecutive patients that undergo a popliteal or infrapopliteal endovascular intervention in seven Dutch hospitals. We estimate that THRILLER will include 400-500 interventions annually. Standardized follow-up visits with wound monitoring, toe pressure measurement and duplex ultrasonography will be scheduled at 6-8 weeks and 12 months after the intervention. The independent primary endpoints are primary patency, limb salvage and amputation free survival. Patients must give informed consent before participation and will be included according to predefined reporting standards. A data log of patients who meet the inclusion criteria but are not included in the registry will be maintained. We intend to conduct the first interim analysis two years after the start of inclusion. The results will be published in a scientific journal. DISCUSSION: Despite innovations in medical therapy and revascularization techniques, patients with CLTI undergoing endovascular revascularization still have a moderate prognosis. Previous prospective cohort studies were hampered by small sample sizes or heterogeneous reporting. Randomized controlled trials (RCTs) have high costs, potential conflicts of interest and give a limited reflection of daily practice. THRILLER aims to provide the largest prospective well phenotyped up-to-date dataset on treatment outcomes in CLTI patients to answer multiple underexplored research questions regarding diagnostics, medication, patient selection, treatment strategies and post intervention follow-up.

Excess Mortality for Abdominal Aortic Aneurysms and the Potential of Strict Implementation of Cardiovascular Risk Management: A Multifaceted Study Integrating Meta-Analysis, National Registry, and PHAST and TEDY Trial Data.

OBJECTIVE: Previous studies imply a profound residual mortality risk following successful abdominal aorta aneurysm (AAA) repair. This excess mortality is generally attributed to increased cardiovascular risk. The aim of this study was (1) to quantify the excess residual mortality for patients with AAA, (2) to evaluate the cross sectional level of cardiovascular risk management, and (3) to estimate the potential of optimised cardiovascular risk management to reduce the excess mortality in these patients. METHODS: Excess mortality was estimated through a systematic review and meta-analysis, and through data from the Swedish National Health Registry. Cardiovascular risk profiles were individually assessed during eligibility screening of patients with AAA for two multicentre pharmaceutical AAA stabilisation trials. The potential of full implementation of cardiovascular risk management was estimated through the validated Second Manifestations of ARTerial disease (SMART) risk scores algorithm. RESULTS: The meta-analysis showed a similarly impaired survival for patients who received early repair (small AAA) or regular repair (≥ 55 mm), and a further impaired survival for patients under surveillance for a small AAA. Excess mortality was further quantified using Swedish population data. The data revealed a more than quadrupled and doubled five year mortality rate for women and men who had their AAA repaired, respectively. Evaluation of the level of risk management of 358 patients under surveillance in 16 Dutch hospitals showed that the majority of patients with AAA did not meet therapeutic targets set for risk management in high risk populations, and indicated a more pronounced prevention gap in women. Application of the SMART risk score algorithm predicted that optimal implementation of risk management guidelines would reduce the 10 year risk of major adverse cardiovascular events from 43% to 14%. CONCLUSION: Independent of the rupture risk, AAA is associated with a worryingly compromised life expectancy with a particularly poor prognosis for women. Optimal implementation of cardiovascular risk prevention guidelines is predicted to profoundly reduce cardiovascular risk.

Feasibility of Photo-Optical Transcutaneous Oxygen Tension Measurement During Revascularization of the Lower Extremity.

OBJECTIVES: A novel approach in the evaluation of peripheral arterial disease is the photo-optical oxygen tension measurement (pTCpO2). This modality is suggested to be more practical in use in comparison to standard electro-chemical oxygen tension measurement. Hence, pTCpO2 might be of added value to evaluate revascularization of the lower extremities peri-procedural. We conducted a preliminary feasibility study to analyze the potential of pTCpO2 during revascularization. METHODS: Ten patients scheduled for revascularization of the lower extremities were enrolled. pTCpO2 values of the affected lower extremity were measured pre-operatively, during revascularization and after revascularization. Results were compared to the pre- and postoperative ankle-brachial index (ABI) and to perioperative angiography. Primary endpoint was the feasibility of perioperative pTCpO2 measurement. Secondary endpoints were concordance between pTCpO2, ABI, angiography and clinical outcome. RESULTS: Two out of twelve measurements were unsuccessful. Eight out of ten patients experienced significant clinical improvement and pTCpO2 increase. Two patients that did not experience clinical improvement corresponded with no changes in intraoperative angiography and without increase in ABI or pTCpO2. A significant and strong correlation was found between prior and after revascularization ABI and pTCpO2 measurements (r = 0.82 P = 0.04). CONCLUSIONS: Photo-optical transcutaneous oxygen tension measurement may serve as an intraoperative tool to evaluate the success of revascularization. pTCpO2 could be an alternative for the ABI to determine the success of lower extremity revascularization.

Mobile applications in peripheral arterial disease (PAD): a review and introduction of a new innovative telemonitoring application: JBZetje.

Introduction:Peripheral arterial disease (PAD) is an occlusive vascular disease of the lower extremities with increasing incidence and prevalence numbers and therefore rising health care costs. Mobile applications have great potential to improve health system efficiency and can assist in overcoming the increasing health care costs. In this review all available mobile applications developed for PAD are summarized and a new innovative application is introduced.Areas covered:Available applications for PAD are scarce and currently aim at prevention, teleconsultation and telemonitoring via questionnaires and activity tracking. Integration in the daily workflow of the physician is an overlooked aspect of these applications. JBZetje is an innovative mobile application that provides remote care, information services and self-service tools, and enables connection with the electronic health record (EHR).Expert opinion:Connection of the application with the EHR generates a complete overview of a patient's current health status. This will reinforce the tendency toward personalized medicine and will probably lead to reduced health care costs and increase the quality of care. Future feasibility studies should answer the question whether the use of mobile applications is feasible in the PAD population.

Photo-Optical Transcutaneous Oxygen Tension Measurement Is of Added Value to Predict Diabetic Foot Ulcer Healing: An Observational Study.

Currently, transcutaneous oxygen tension measurement (TCpO2) is the most favorable non-invasive test for diabetic foot ulcer (DFU) healing prognosis. Photo-optical TCpO2 is novel, less time-consuming and more practical in use compared to regular electro-chemical TCpO2. We prospectively investigated the clinical value of photo-optical TCpO2 to predict DFU healing. Patients with suspected DFU undergoing conservative treatment underwent an ankle pressure, toe-pressure and photo-optical TCpO2 test. The primary endpoint was DFU wound healing at 12 months. Based on their clinical outcome, patients were divided into a DFU healing and DFU non-healing group. Healing was defined as fully healed ulcers and non-healing as ulcers that deteriorated under conservative treatment or that required surgical amputation. Differences between groups were analyzed and an optimal TCpO2 cut-off value was determined. In total, 103 patients were included, of which 68 patients (66%) were classified as DFU healing. The remaining 35 patients (34%) had deteriorated ulcers, of which 29 (83%) eventually required surgical amputation. An optimal TCpO2 cut-off value of 43 mmHg provided a sensitivity, specificity and odds ratio of 0.78, 0.56 and 4.4, respectively. Photo-optical TCpO2 is an adequate alternative tool to validate the vascular status of the lower extremity indicating healing prognosis in patients with DFU. Therefore, we recommend that photo-optical TCpO2 can be safely coapplied in clinical practice to assist in DFU treatment strategy.

Midterm Outcomes of Drug-Coated Balloon Angioplasty in Femoropopliteal Lesions in a Daily Practice Cohort.

BACKGROUND: Most previous drug-coated balloon (DCB) angioplasty studies used strict inclusion and exclusion criteria and therefore might not be representative for daily practice. This study was performed to evaluate the midterm outcomes of DCB angioplasty in femoropopliteal artery disease and to identify risk factors for restenosis. MATERIALS AND METHODS: All patients treated with DCB angioplasty between January 2015 and September 2016 were included. Provisional stents were placed if indicated. Data were retrospectively collected from digital patient records. No exclusion criteria were applied. The primary end point was primary patency. Secondary end points were primary assisted patency, secondary patency, clinically driven target lesion revascularization (CD-TLR) and major adverse events. All end points were calculated with the Kaplan-Meier analysis. The univariable and multivariable Cox regression analyses were performed to identify risk factors for restenosis. RESULTS: A total of 109 patients (113 legs) were included (45% male; mean age, 72 ± 10). The rate of critical limb ischemia was 52% and total occlusions were treated in 38%. The mean follow-up was 24 ± 13 months. Primary patency rates were 87%, 79%, and 61% at 1, 2, and 3 years, respectively. Primary assisted patency rates were 95%; 89%, and 79%; secondary patency rates were 99%, 97%, and 91%; and CD-TLR rates were 6.9%, 14.3%, and 20.6% at 1, 2, and 3 years, respectively. Overall mortality and major target limb amputation rates were 18% and 5% at 3 years. Multivariable analysis demonstrated that only Trans-Atlantic Inter-Society Consensus (TASC) D lesions were associated with restenosis (P = 0.008). CONCLUSIONS: DCB angioplasty is an effective and safe treatment option for femoropopliteal lesions in daily practice with excellent 1- and 2-year results. The 3-year results were slightly less favorable, which may be caused by the ongoing vascular disease or a late "catch-up" phenomenon. Only TASC D lesions were associated with loss of primary patency after adjustment for confounders.

Meta-analysis of Individual Patient Data After Kissing Stent Treatment for Aortoiliac Occlusive Disease.

PURPOSE: To evaluate short- and long-term technical and clinical outcomes after kissing stent treatment of aortoiliac occlusive disease (AIOD) based on an individual participant data (IPD) meta-analysis. MATERIALS AND METHODS: A search of the Scopus database identified 156 articles on KS treatment of AIOD; of these 22 met the inclusion criteria. Authors of 19 articles with contact information were approached to join an IPD consortium. Eight author groups responded and 5 provided anonymized data for merging into an IPD database. The number of included procedures was equal before and after 2005. The primary study outcome was the cumulative patency at 24 months. Secondary outcomes were patency at up to 60 months, complications, and changes in Rutherford category and ankle-brachial index. The predictive value of stent protrusion length, pre-/postdilation, stent type, and patient demographics on primary patency were examined with Cox proportional hazard modeling; outcomes are reported as the hazard ratio (HR). The Kaplan-Meier method was employed to estimate patency rates. RESULTS: In total, 605 (40.9%) of 1480 patients presented in the literature were included in the IPD analysis. The indication for intervention was intermittent claudication in 84.2% and critical limb ischemia in 15.8%. Lesions were classified as TransAtlantic Inter-Society Consensus (TASC) A or B in 52.8% and TASC C and D in 47.2%. The overall primary patency estimate was 81% at 24 months. Primary patency significantly increased after 2005 (p=0.005). Cox regression analysis revealed only age as a significant predictor of sustained primary patency (HR 0.60, p<0.005). Any previous endovascular intervention (HR 2.52, p=0.02) was the main predictor for loss of secondary patency; history of cardiovascular disease (HR 0.27, p=0.04) was the main predictor of sustained secondary patency. CONCLUSION: The kissing stent technique has a good safety profile and acceptable patency rates up to 2 years, even in TASC C and D lesions, supporting an endovascular-first approach for AIOD.

Short-term outcome and mid-term access site complications of the percutaneous approach to endovascular abdominal aortic aneurysm repair (PEVAR) after introduction in a vascular teaching hospital.

The objective is to evaluate our center's experience with the safety and efficacy of the percutaneous approach to endovascular abdominal aortic aneurysm repair (PEVAR) with use of the Perclose Proglide device, in the first period after introduction in our center in 2014. We retrospectively identified all patients that underwent PEVAR or endograft extension with percutaneous approach in our center in the urgent and elective setting. Included were all procedures performed between the introduction of the technique in January 2014 and February 2016 when PEVAR had become the predominant technique in our center. Exclusion progressed from expected difficulty of the procedure as estimated by the operator to total calcification of the ventral wall of the CFA towards the end of the study period. Surgical and clinical reports were used to analyze patient characteristics, procedural success, and short-term outcome after 30 days. Follow-up imaging was used to assess mid-term access site complications at 1 and 2 years postoperatively. A univariate regression analysis was conducted to determine significant predictors of access-related complications with the Perlcose Proglide system. Of all 78 patients (mean age 74, SD: 7 years, 70 men), 68 (87.2%) underwent PEVAR and 10 (12.8%) underwent endograft extension procedures with percutaneous approach. Sixty-seven (85.9%) patients underwent an elective procedure and 11 (14.1%) patients underwent urgent PEVAR. The total number of vessels that was percutaneously accessed was 142. Direct technical success of the procedure as analyzed per vessel was 98.6% (140/142), with two cases of conversion to the femoral cut-down approach. A total of 274 Perclose Proglide devices were placed. Device failure of the Perclose device occurred in 5.8% (16/274) and was reason for conversion to cut-down procedure in one case. Mean duration of the procedure and median time of hospitalization were 100 (SD: 34) min and 2 (IQR 1, 3) days, respectively. Event-free survival per vessel after 30 days was 91.0%, with two minor access-related complication. Fifty-five individual patients (105 vessels) were eligible for inclusion in the 1-year follow-up analysis. Of these patients, 19 (34 vessels) could be included in the 2-year follow-up analysis. No additional access site complications occurred at mid-term follow-up. No significant predictors of device failure were found. The percutaneous approach to EVAR appears to be a safe and effective option with high success rate and low complication rate in a real-world setting. Based on our findings, we conclude that the technique can safely be introduced in a vascular center.

Inadequate Health Literacy in Patients with Arterial Vascular Disease.

OBJECTIVE: The aim was to identify the prevalence of inadequate health literacy in patients with arterial vascular disease. This was a cross sectional study. METHODS: Patients with arterial vascular disease visiting the outpatient clinic between January 5, 2015 and December 28, 2016, were randomly included and screened for inadequate health literacy with the Newest Vital Sign-Dutch (NVS-D), a validated health literacy assessment measure. A score of <4 out of six identified individuals with inadequate health literacy. Age, gender, highest education level, and reason for consultation were also registered. Data analysis was performed using Student's t-test or the Mann-Whitney U test and chi-square test. Logistic regression with backward elimination was applied to identify independent predictors. RESULTS: A total of 202 patients were included. The mean NVS-D score was 1.91 (SD ± 1.948, median 1). The prevalence of inadequate health literacy was 76.7%. A significantly higher prevalence of inadequate health literacy was found in patients ≥65 years (p < .001) and patients with a lower education level (p < .001). No significant difference was found between female/male patients (p = .056), nor between participants with peripheral arterial occlusive disease and abdominal aortic aneurysm (p = .116). Age (OR 1.060; 95% CI 1.017-1.104; p = .005) and education level (OR 0.164; 95% CI 0.078-0.346; p < .001) were identified as independent predictors of inadequate health literacy. CONCLUSION: This study shows a prevalence of inadequate health literacy of 76.7% in patients with arterial vascular disease, with a significantly higher prevalence in patients ≥ 65 years and patients with a lower education level. The high prevalence of inadequate health literacy should be considered when information is provided, and suggests the need to further investigate the best methods to convey medical information to this group of vulnerable patients.

ACE inhibitors potently reduce vascular inflammation, results of an open proof-of-concept study in the abdominal aortic aneurysm.

BACKGROUND: Independent of their blood pressure lowering effect, ACE inhibitors are thought to reduce vascular inflammation. The clinical relevance of this effect is unclear with the current knowledge. Abdominal aortic aneurysms (AAA) are characterized by a broad, non-specific inflammatory response, and thus provide a clinical platform to evaluate the anti-inflammatory potential of ACE inhibitors. METHODS AND RESULTS: Eleven patients scheduled for open AAA repair received ramipril (5 mg/day) during 2-4 weeks preceding surgery. Aortic wall samples were collected during surgery, and compared to matched samples obtained from a biobank. An anti-inflammatory potential was evaluated in a comprehensive analysis that included immunohistochemistry, mRNA and protein analysis. A putative effect of ACE inhibitors on AAA growth was tested separately by comparing 18-month growth rate of patients on ACE inhibitors (n = 82) and those not taking ACE inhibitors (n = 204). Ramipril reduces mRNA expression of multiple pro-inflammatory cytokines such as IL-1ß, IL-6, IL-8, TNF -α, Interferon-[Formula: see text], and MCP-1, as well as aortic wall IL-8 and MCP-1 (P = 0.017 and 0.008, respectively) protein content. The is followed by clear effects on cell activation that included a shift towards anti-inflammatory macrophage (M2) subtype. Evaluation of data from the PHAST cohort did not indicate an effect of ACE inhibitors on 18-month aneurysm progression (mean difference at 18 months: -0.24 mm (95% CI: -0.90-0.45, P = NS). CONCLUSIONS: ACE inhibition quenches multiple aspects of vascular inflammation in AAA. However, this does not translate into reduced aneurysm growth. TRIAL REGISTRATION: Nederlands Trial Register 1345.

Treatment of types II-IV endoleaks by injecting biocompatible elastomer (PDMS) in the aneurysm sac: an in vitro study.

PURPOSE: To investigate if an elastomer [polydimethylsiloxane (PDMS)] can be used to effectively treat endoleaks after endovascular aneurysm repair. METHODS: A latex aneurysm (36-mm inner diameter sac, 15-mm inner diameter neck) was attached to an in vitro circulation model. The aneurysm was excluded from the circulation by placing an unstented polyester graft. Endoleak types II-IV were created using different setups. While the circulation setup running, the aneurysm was filled with contrast medium and then the biocompatible PDMS elastomer was injected to exclude the endoleaks and the perigraft area. The sac was considered full when all contrast was pushed out of the sac and the elastomer flowed into the proximal efferent lumbar artery. Treatment was successful when the aneurysm was free of endoleak after control angiography. RESULTS: The endoleaks were created successfully in the latex aneurysm models, with contrast present in the sac before "treatment." After elastomer sac filling, all endoleaks were successfully excluded on angiography; there was no leakage of contrast outside the graft lumen in any of the setups. With the type III endoleak, the disruption in the graft material was sealed by the elastomer, while the entire porous graft was encased in elastomer in the type IV endoleak setup. There was no elastomer within the graft lumen in either case. CONCLUSIONS: This concept of filling the aneurysm sac with PDMS may lead to a percutaneous treatment for endoleaks. While the results of this study show that PDMS may be used to treat endoleaks in vitro, further tests are required to determine if this approach is suitable in vivo.

Aortic customize: a new alternative endovascular approach to aortic aneurysm repair using injectable biocompatible elastomer. An in vitro study.

PURPOSE: Aortic Customize is a new concept for endovascular aortic aneurysm repair in which a non polymerized elastomer is injected to fill the aneurysm sac around a balloon catheter. The aim of this in vitro study was to investigate the extent of aneurysm wall stress reduction by the presence of a noncompliant elastomer cuff. METHODS: A thin-walled latex aneurysm (inner radius sac 18 mm, inner radius neck 8 mm), equipped with 12 tantalum markers, was attached to an in vitro circulation model. Fluoroscopic roentgenographic stereo photogrammetric analysis (FRSA) was used to measure marker movement during six cardiac cycles. The radius of three circles drawn through the markers was measured before and after sac filling. Wall movement was measured at different systemic pressures. Wall stress was calculated from the measured radius (sigma = pr/2t). RESULTS: The calculated wall stress was 7.5-15.6 N/cm(2) before sac filling and was diminished to 0.43-1.1 N/cm(2) after sac filling. Before sac filling, there was a clear increase (P < .001) in radius of the proximal (range, 7.9%-33.5%), middle (range, 3.3%-25.2%), and distal (range, 10.5%-184.3%) rings with increasing systemic pressure. After sac filling with the elastomer, there remained a small, significant (P < .001) increase in the radius of the circles (ranges: 6.8%-8.8%; 0.7%-1.1%; 5.3%-6.7%). The sac filling reduced the extent of radius increase. The treated aneurysm withstood systemic pressures up to 220/140 mm Hg without noticeable wall movement. After the sac filling, there was no pulsation visible in the aneurysm wall. CONCLUSIONS: Filling the aneurysm sac of a simplified in vitro latex model with a biocompatible elastomer leads to successful exclusion of the aneurysm sac from the circulation. Wall movement and calculated wall stress are diminished noticeably by the injection of biocompatible elastomer.

Effect of stent-graft compliance on endotension after EVAR.

PURPOSE: To investigate whether, and to which extent, the type of graft has influence on the pressure in the aneurysm sac. METHODS: The study consisted of a dynamic and a static experiment. In the dynamic experiment, a latex aneurysm was inserted into an in-vitro circulation model, with variable (80-180 mmHg) systemic systolic pressure and a pulse pressure of 40 mmHg. Seven types of devices were used to exclude the aneurysm: a latex reference graft, 3 stentless grafts made of different fabrics, and 3 different types of commercially produced stented grafts used for endovascular aneurysm repair (EVAR). The systolic and diastolic intra-aneurysm pressures (IAP) were measured, along with the pulse pressure. The mean IAP and pulse pressures were compared for each category of graft (stented/stentless) and for each graft. In the static experiments, the compliance of each graft and the latex aneurysm were determined by measuring the change in volume necessary to obtain a change in pressure. Furthermore, the IAP with each graft was measured in a nonpulsatile situation under systolic pressures varying between 60 and 140 mmHg. RESULTS: The experiments showed that, with increasing systemic pressures, there was a small pressure (<5 mmHg) increase in the aneurysm, but there was no significant difference among grafts in the dynamic or the static experiments (p = 0.12 and p = 0.17, respectively). With the 3 stented EVAR grafts, there was less pressure transmission than with the 3 stentless grafts, but this difference was not significant (p>0.05). CONCLUSION: This in-vitro study demonstrated that there is a clinically irrelevant pressure transmission through the graft wall and no significant difference in the pressure transmission between stented and stentless grafts.

Assessment of three-dimensional stent-graft dynamics by using fluoroscopic roentgenographic stereophotogrammetric analysis.

OBJECTIVE: To validate the use of fluoroscopic roentgenographic stereophotogrammetric analysis (FRSA) for its feasibility and accuracy for measuring the three-dimensional dynamic motion of stent grafts. METHODS: A digital biplane fluoroscopy setup was calibrated (Siemens Axiom Artis dBc). Stereo images were acquired of a static aortic model with a stent graft in different axial positions, imposed by a micromanipulator. The three-dimensional measurement error of FRSA was determined by comparing FRSA measurements with the micromanipulator. An aortic model with a stent graft was constructed and connected to an artificial circulation with a physiological flow and pressure profile. Markers were added to the spine (tantalum spherical markers; diameter 1 mm) and stent (welding tin; diameter 1 mm). The three-dimensional measurement precision was determined by measuring the position of a single (stable) spine marker during two pulsatile cycles. Finally, three-dimensional stent marker motion was analyzed with a frame rate of 30 images per second, including three-dimensional marker position (change), diameter change, and center of circle position change. RESULTS: The mean error of FRSA measurement of displacement was 0.003 mm (SD, 0.019 mm; maximum error, 0.058 mm). A very high precision of position measurement was found (SD, 0.009-0.015 mm). During pulsatile motion, the position (changes) of the markers could be assessed in the x, y, and z directions, as well as the stent diameter change and center of circle position change. CONCLUSIONS: FRSA has proven to be a method with very high accuracy and temporal resolution to measure three-dimensional stent-graft motion in a pulsatile environment. This technique has the potential to contribute significantly to the knowledge of stent-graft behavior after endovascular aneurysm repair and improvements in stent-graft design. The technique is ready for clinical testing.

Aneurysm sac pressure monitoring: does the direction of pressure measurement matter in fibrinous thrombus?

PURPOSE: This study was conducted to clarify the effect of the direction of pressure measurement on the pressure readout in fibrinous thrombus of the abdominal aortic aneurysm. METHODS: Three weights of 468 g (weight 1), 578 g (weight 2), and 675 g (weight 3) were molded. A specimen of human fibrinous thrombus was positioned under the weights. Because the surface area of the weights and the thrombus was 400 mm(2), weights 1, 2, and 3 caused pressures of 88, 108, and 127 mm Hg, respectively. Pressure measurements were performed at different angles between the sensor and the applied force (0 degrees , 22.5 degrees , 30 degrees , 45 degrees , 60 degrees , 67.5 degrees , 90 degrees ) Thrombi of 10 different patients were analyzed. Pressure measurements in the thrombi at different angles were statistically compared by a linear mixed model analysis. RESULTS: The measurements at 90 degrees differed statistically from the measurements at 0 degrees , 22.5 degrees , 30 degrees , 45 degrees , 60 degrees , and 67.5 degrees (P < .001). The pressure readout was only similar to the applied pressure when the pressure sensor was positioned at 90 degrees to the applied force. Pressure measurements in other sensor positions resulted in lower pressure measurements. Pressure changes were detected in all sensor positions. There appeared to be no significant difference between the pressure measurements taken at same angles in the 10 thrombi (P > .05). CONCLUSION: In fibrinous thrombus of abdominal aortic aneurysm, the direction of pressure measurement influenced the pressure readout.

Accurate detection of stent-graft migration in a pulsatile aortic model using Roentgen stereophotogrammetric analysis.

PURPOSE: To evaluate the feasibility and accuracy of Roentgen stereophotogrammetric analysis (RSA) versus computed tomography (CT) for detecting stent-graft migration in an in vitro pulsatile circulation model and to study the feasibility of a nitinol endovascular clip (NEC) as an aortic wall reference marker for RSA. METHODS: An aortic model with stent-graft was constructed and connected to an artificial circulation with a physiological flow and pressure profile. Tantalum markers and NECs were used as aortic reference markers for RSA analysis. Stent-graft migrations were measured during pulsatile circulation with RSA and CT. CT images acquired with 64 x 0.5-mm beam collimation were analyzed with Vitrea postprocessing software using a standard clinical protocol and central lumen line reconstruction. RSA in the model with the circulation switched off was used as the reference standard to determine stent-graft migration. The measurement errors of RSA and CT were determined during pulsatile circulation. RESULTS: The mean measurement error +/- standard deviation (maximum) of RSA during pulsatile circulation using the tantalum markers was -0.5+/-0.16 (0.7) mm. Using the NEC, the mean (maximum) measurement error was -0.4+/-0.25 (1.1) mm. The mean (maximum) measurement error of CT was -1.1+/-1.17 (2.8) mm. CONCLUSION: RSA is an accurate and feasible tool to measure stent-graft migration in a pulsatile environment. Migration measurement with RSA was more accurate than CT in this experimental setup. The nitinol clip tested in this study is potentially feasible as an aortic reference marker in patients after endovascular repair.

Roentgen stereophotogrammetric analysis: an accurate tool to assess stent-graft migration.

PURPOSE: To evaluate in an in vitro model the feasibility and accuracy of Roentgen stereophotogrammetric analysis (RSA) versus computed tomography (CT) for the ability to detect stent-graft migration. METHODS: An aortic model was constructed from a 22-mm-diameter Plexiglas tube with 6-mm polytetrafluoroethylene inlays to mimic the renal arteries. Six tantalum markers were placed in the wall of the aortic tube proximal to the renal arteries. Another 6 markers were added to a Gianturco stent, which was cast in Plexiglas and placed inside the aorta and fixed to a micromanipulator to precisely control displacement of the stent along the longitudinal axis. Sixteen migrations were analyzed with RSA software and compared to the micromanipulator. Thirty-two migrations were measured by 3 observers from CT images acquired with 16x0.5-mm beam collimation and reconstructed with a 0.5-mm slice thickness and a 0.4-mm reconstruction interval. Measurements were made with Vitrea postprocessing software using a standard clinical protocol and central lumen line reconstruction. Results of CT were also compared to the micromanipulator. RESULTS: The mean RSA measurement error compared to the micromanipulator was 0.002+/-0.044 mm, and the maximum error was 0.10 mm. There was no statistically significant interobserver variability for CT (p=0.17). The pooled mean (maximum) measurement error of CT was 0.14+/-0.29 (1.00) mm, which was significantly different from the RSA measurement error (p<0.0001). CONCLUSION: Detection of endograft migration by RSA is feasible and was significantly more accurate than CT in this nonpulsatile in vitro model.

Technique for safe removal of an aortic endograft with suprarenal fixation.

Complete removal of an aortic endograft with suprarenal fixation is difficult. We report the use of a simple device to extract a Zenith endograft. This device is made by cutting off the tip of the cylinder of a 20-mL syringe and rounding off the edges. The main body of the graft is resheathed by advancing the cylinder cranially while keeping the graft in a stable position. This way, the graft collapses and the hooks are withdrawn without tearing the wall of the aorta. The supraceliac clamping time in our patient was less than 2 minutes. This technique offers a safe and fast solution to the potentially hazardous removal of an aortic endograft with suprarenal fixation.