Self-expanding stents and aortoiliac occlusive disease: A review of the literature

The treatment of symptomatic aortoiliac occlusive disease has shifted from open to endovascular repair. Both short- and long-term outcomes after percutaneous angioplasty and stenting rival those after open repair and justify an endovascular-first approach. In this article, we review the current endovascular treatment strategies in patients with aortoiliac occlusive disease, indications for primary and selective stenting in the iliac artery, and physical properties and future perspectives of self-expanding stents

DISCOVER: Dutch Iliac Stent trial: COVERed balloon-expandable versus uncovered balloon-expandable stents in the common iliac artery: Study protocol for a randomized controlled trial

Background: Iliac artery atherosclerotic disease may cause intermittent claudication and critical limb ischemia. It can lead to serious complications such as infection, amputation and even death. Revascularization relieves symptoms and prevents these complications. Historically, open surgical repair, in the form of endarterectomy or bypass, was used. Over the last decade, endovascular repair has become the first choice of treatment for iliac arterial occlusive disease. No definitive consensus has emerged about the best endovascular strategy and which type of stent, if any, to use. However, in more advanced disease, that is, long or multiple stenoses or occlusions, literature is most supportive of primary stenting with a balloon-expandable stent in the common iliac artery (Jongkind V et al., J Vasc Surg 52:1376-1383,2010). Recently, a PTFE-covered balloon-expandable stent (Advanta V12, Atrium Medical Inc., Hudson, NH, USA) has been introduced for the iliac artery. Covering stents with PTFE has been shown to lead to less neo-intimal hyperplasia and this might lower restenosis rates (Dolmatch B et al. J Vasc Interv Radiol 18:527-534,2007, Marin ML et al. J Vasc Interv Radiol 7:651-656,1996, Virmani R et al. J Vasc Interv Radiol 10:445-456,1999). However, only one RCT, of mediocre quality has been published on this stent in the common iliac artery (Mwipatayi BP et al. J Vasc Surg 54:1561-1570,2011, Bekken JA et al. J Vasc Surg 55:1545-1546,2012). Our hypothesis is that covered balloon-expandable stents lead to better results when compared to uncovered balloon-expandable stents.Methods/Design: This is a prospective, randomized, controlled, double-blind, multi-center trial. The study population consists of human volunteers aged over 18 years, with symptomatic advanced atherosclerotic disease of the common iliac artery, defined as stenoses longer than 3 cm and occlusions. A total of 174 patients will be included.The control group will undergo endovascular dilatation or revascularization of the common iliac artery, followed by placement of one or more uncovered balloon-expandable stents. The study group will undergo the same treatment, however one or more PTFE-covered balloon-expandable stents will be placed. When necessary, the aorta, external iliac artery, common femoral artery, superficial femoral artery and deep femoral artery will be treated, using the standard treatment.The primary endpoint is absence of binary restenosis rate. Secondary endpoints are reocclusion rate, target-lesion revascularization rate, clinical success, procedural success, hemodynamic success, major amputation rate, complication rate and mortality rate. Main study parameters are age, gender, relevant co-morbidity, and several patient, disease and procedure-related parameters. Trial registration: Dutch Trial Register, NTR3381

Randomized trial of Legflow® paclitaxel eluting balloon and stenting versus standard percutaneous transluminal angioplasty and stenting for the treatment of intermediate and long lesions of the superficial femoral artery (RAPID trial): Study protocol for a randomized controlled trial

Background: Restenosis after percutaneous transluminal angioplasty (PTA) of the superficial femoral artery (SFA) may occur in 45% of patients at 2 years follow-up. Paclitaxel-coated balloons have been found to reduce neointimal hyperplasia, and thus reduce restenosis. Recently, the Legflow® paclitaxel-coated balloon (Cardionovum Sp.z.o.o., Warsaw, Poland) (LPEB) has been introduced. This balloon is covered with shellac, a Food and Drug Administration (FDA) approved natural resin, to obtain an equally distributed tissue concentration of paclitaxel. The RAPID trial is designed to assess restenosis after PTA using the Legflow balloon combined with nitinol stenting versus uncoated balloons with nitinol stenting in SFA lesions >5 cm.Methods/Design: A total of 176 adult patients with Rutherford class 2 to class 6 symptoms due to intermediate (5-15 cm) or long (>15 cm) atherosclerotic lesions in the SFA will be randomly allocated for treatment with LPEB with nitinol stenting or uncoated balloon angioplasty with stenting. Stenting will be performed using the Supera® stent in both groups (IDEV Technologies Inc., Webster, TX). The primary endpoint is the absence of binary restenosis of the treated SFA segment. Secondary outcomes are target lesion revascularization (TLR), clinical and hemodynamic outcome, amputation rate, mortality rate, adverse events, and device-specific adverse events. Follow up consists of four visits in which ankle-brachial indices (ABI), toe pressure measurements, and duplex ultrasound (DUS) will be performed. Furthermore, a peripheral artery questionnaire (PAQ) will be completed by the patients at each follow-up. In the event that DUS reveals a symptomatic >50% restenosis, or a >75% asymptomatic restenosis, additional digital subtraction angiography will be performed with any necessary re-intervention.Discussion: The RAPID trial is a multicenter randomized controlled patient blind trial that will provide evidence concerning whether the use of the Legflow paclitaxel/shellac coated balloons with nitinol stenting significantly reduces the frequency of restenosis in intermediate and long SFA lesions compared to standard PTA and stenting.Trial registration: ISRCTN47846578

Type 2 Endoleak With or Without Intervention and Survival After Endovascular Aneurysm Repair

Objective: The aims of the present study were to examine the impact of type 2 endoleaks (T2EL) on overall survival and to determine the need for secondary intervention after endovascular aneurysm repair (EVAR). Methods: A multicentre retrospective cohort study in the Netherlands was conducted among patients with an infrarenal abdominal aortic aneurysm (AAA) who underwent EVAR between 2007 and 2012. The primary endpoint was overall survival for patients with (T2EL+) or without (T2EL-) a T2EL. Secondary endpoints were sac growth, AAA rupture, and secondary intervention. Kaplan–Meier survival and multivariable Cox regression analysis were used. Results: A total of 2 018 patients were included. The median follow up was 62.1 (range 0.1 – 146.2) months. No difference in overall survival was found between T2EL+ (n = 388) and T2EL- patients (n = 1630) (p =.54). The overall survival estimates at five and 10 years were 73.3%/69.4% and 45.9%/44.1% for T2EL+/T2EL- patients, respectively. Eighty-five of 388 (21.9%) T2EL+ patients underwent a secondary intervention. There was no difference in overall survival between T2EL+ patients who underwent a secondary intervention and those who were treated conservatively (p =.081). Sac growth was observed in 89 T2EL+ patients and 44/89 patients (49.4%) underwent a secondary intervention. In 41/44 cases (93.1%), sac growth was still observed after the intervention, but was left untreated. Aneurysm rupture occurred in 4/388 T2EL patients. In Cox regression analysis, higher age, ASA classification, and maximum iliac diameter were significantly associated with worse overall survival. Conclusion: No difference in overall survival was found between T2EL+ and T2EL- patients. Also, patients who underwent a secondary intervention did not have better survival compared with those who did not undergo a secondary intervention. This study reinforces the need for conservative treatment of an isolated T2EL and the importance of a prospective study to determine possible advantages of the intervention

Determination of the relation between alterations of total body water and thoracic fluid content during ultrafiltration by bioelectrical impedance analysis

Total body impedance (TBI) is used to monitor alterations in total body water (TBW), e.g. during haemodialysis.However, 80%of the TBI signal is due to the resistance in extremities. Therefore TBI measurements give littleinformation about alterations in thoracic fluid content (TF). Measuring both total body impedance and thoracic impedance (THI) can be a useful method to monitor TBW and TF changes during haemodialysis. In this study TBI and THI measurements were performed during 30 dialysis sessions and also in one group of 24 control subjects with normal tissue hydration. During haemodialysis TBI and THI significantly increased, demonstrating a decrease of TBW and TF. The ratio THI/TBI did not differ significantly during haemodialysis, indicating a similar effect of ultrafiltration on TBW and TF. The finding that TF decreased during haemodialysis was rather surprising, whereas pulmonary oedema is not an evident clinicalproblem in patients on maintenance haemodialysis treatment. THI measurements after dialysis proved to be signifiantlyhigher in comparison to the control subjects. This finding supports the hypothesis that the decrease in TF during dialysis is partly due to the sudden ultrafiltration-induced hypo-volaemia leading to a fall in thoracic blood volume

Bioelectrical impedance analysis: Clinical tool in assessing total body water and thoracic fluid

Bioelectrical impedance analysis forms a non-invasive fool for defection of body fluids. Total body measurement gives total body water (TBW) and, in case of multifrequency analysis, of intra- and extracellular fluid volume. The thoracic approach measures thoracic fluid (TF). The set-up of both techniques is discussed. An overview is given of the clinical usefulness of the total body technique to monitor fluid changes and the process of refill during hemodialysis and to detect dry weight. The simultaneous measurement of TBW and TF was applied to obtain a more detailed picture of the body fluids. In a group of healthy subjects the age dependency of both variables was shown. During hemodialysis TBW and TF showed a major and comparable decrease. Fluid retention during cardiac surgery led to a slightly more pronounced increase of TF than of TBW. The combination of both impedance techniques offers clinicians a means to monitor alterations in fluid status in patients in more detail

Aortic curvature instead of angulation allows improved estimation of the true aorto-iliac trajectory

Objective: Supra- and infrarenal aortic neck angulation have been associated with complications after endovascular aortic aneurysm repair. However, a uniform angulation measurement method is lacking and the concept of angulation suggests a triangular oversimplification of the aortic anatomy. (Semi-)automated calculation of curvature along the center luminal line describes the actual trajectory of the aorta. This study proposes a methodology for calculating aortic (neck) curvature and suggests an additional method based on available tools in current workstations: curvature by digital calipers (CDC). Methods: Proprietary custom software was developed for automatic calculation of the severity and location of the largest supra- and infrarenal curvature over the center luminal line. Twenty-four patients with severe supra- or infrarenal angulations (≥45°) and 11 patients with small to moderate angulations (<45°) were included. Both CDC and angulation were measured by two independent observers on the pre- and postoperative computed tomographic angiography scans. The relationships between actual curvature and CDC and angulation were visualized and tested with Pearson's correlation coefficient. The CDC was also fully automatically calculated with proprietary custom software. The difference between manual and automatic determination of CDC was tested with a paired Student t test. A p-value was considered significant when two-tailed α <.05. Results: The correlation between actual curvature and manual CDC is strong (.586-.962) and even stronger for automatic CDC (.865-.961). The correlation between actual curvature and angulation is much lower (.410-.737). Flow direction angulation values overestimate CDC measurements by 60%, with larger variance. No significant difference was found in automatically calculated CDC values and manually measured CDC values. Conclusion: Curvature calculation of the aortic neck improves determination of the true aortic trajectory. Automatic calculation of the actual curvature is preferable, but measurement or calculation of the curvature by digital calipers is a valid alternative if actual curvature is not at hand

Prognosis review and time-to-event data meta-analysis of endovascular aneurysm repair outside versus within instructions for use of aortic endograft devices

Background: Our objective was to investigate whether patients undergoing standard endovascular aneurysm repair (EVAR) outside the instructions for use (IFU) have worse outcomes than patients treated within IFU. Methods: We conducted a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Electronic bibliographic sources were searched up to January 2019 using a combination of controlled vocabulary (thesaurus) and free-text terms to identify studies comparing outcomes of EVAR in patients treated outside versus within IFU. Pooled estimates of dichotomous outcomes were calculated using odds ratio (OR) or risk difference (RD) and 95% confidence interval (CI). We conducted a time-to-event data meta-analysis using the inverse-variance method and reported the results as summary hazard ratio (HR) and associated 95% CI. Random-effects methods of meta-analysis were applied. We formed meta-regression models to explore heterogeneity as a result of changes in practice over time. Results: We identified 17 observational cohort studies published between 2011 and 2017, reporting a total of 4498 patients. The pooled prevalence of EVAR performed outside the IFU was 40% (95% CI, 33-48). Nonadherence to IFU was not associated with increased risk of perioperative mortality (RD, 0.01; 95% CI, −0.00 to 0.01; P = .23), aneurysm rupture (HR, 1.34; 95% CI, 0.30-5.93; P = .70), aneurysm-related mortality (HR, 0.88; 95% CI, 0.20-3.84; P = .86), technical failure (RD, 0.01; 95% CI, −0.03 to 0.05; P = .56), requirement for adjunctive procedures (OR, 1.48; 95% CI, 0.81-2.71; P = .20), type I endoleak (HR, 2.28; 95% CI, 0.58-8.91; P = .24), aneurysm sac expansion (HR, 0.86; 95% CI, 0.55-1.33; P = .49), or aneurysm-related reintervention (HR, 1.04; 95% CI, 0.81-1.34; P = .74). The overall mortality was significantly higher in patients treated outside the IFU (HR, 1.20; 95% CI, 1.02-1.42; P = .03). Meta-regression showed that the prevalence of EVAR performed outside the IFU has increased over time (P = .019). Conclusions: Standard EVAR outside the IFU was not found to have worse aneurysm-related outcomes than treatment within the IFU. Standard EVAR outside the IFU could be considered in selected patients who are deemed high risk for complex open or endovascular surgery. © 2019 Society for Vascular Surger