Structural failures in abdominal aortic aneurysm stentgrafts: Threat to durability and challenge to technology

What limits the Implementation of Internet of Things (IoT)? A Picture of Indonesian Market

In the field of Industry 4.0, various studies considered the engineering industries, however, the limitations of Internet of things (IoT) implementation is not discussed by these studies and literature missed the crucial challenges of IoT implementation, particularly in the Indonesian engineering companies. Therefore, the objective of the current study is to investigate the factors which limits the implementation of IoT. Additionally, the moderating role of employee innovative capabilities is also considered. A survey was carried out in the Indonesian engineering companies for data collection. Data collection was carried out form the employees of these companies. After data collection, structural equation modeling (SEM) was used to analyse the data with the help of Partial Least Square (PLS). Findings of the study demonstrated that there are five key factors which effect the IoT implementation. These factors include; willingness to use, hardware characteristics, replacement of existing technology, failure threat and implementation cost. All these factors have the ability to influence IoT implementation. Additionally, employee innovative capability also has the ability to encourage or discourage the IoT implementation. Therefore, this study is most significant for the engineering industry of Indonesia as it provides the influencing factors towards IoT implementation.

Compliance Study of Endovascular Stent Grafts Incorporated with Polyester and Polyurethane Graft Materials in both Stented and Unstented Zones

Compliance mismatch between stent graft and host artery may induce complications and blood flow disorders. However, few studies have been reported on stent graft compliance. This study aims to explore the deformation and compliance of stent graft in stented and unstented zones under three pressure ranges. Compliance of two stent grafts incorporated with polyurethane graft (nitinol-PU) and polyester graft (nitinol-PET) materials respectively were tested; the stents used in the two stent grafts were identical. For the circumferential deformation of the stent grafts under each pressure range, the nitinol-PET stent graft was uniform in both zones. The nitinol-PU stent graft was circumferentially uniform in the stented zone, however, it was nonuniform in the unstented zone. The compliance of the PU graft material was 15 times higher than that of the PET graft. No significant difference in compliance was observed between stented and unstented zones of the nitinol-PET stent graft regardless of the applied pressure range. However, for the nitinol-PU stent graft, compliance of the unstented PU region was approximately twice that of the stented region; thus, compliance along the length of the nitinol-PU stent graft was not constant and different from that of the nitinol-PET stent graft.

An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents

Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.

Essentials of endovascular abdominal aortic aneurysm repair imaging: postprocedure surveillance and complications

OBJECTIVE

Lifelong postprocedural imaging surveillance is necessary after endovascular abdominal aortic aneurysm repair (EVAR) to assess for complications of endograft placement, as well as device failure and continued aneurysm growth. Refinement of the surveillance CT technique and development of ultrasound and MRI protocols are important to limit radiation exposure.

CONCLUSION

A comprehensive understanding of EVAR surveillance is necessary to identify life-threatening complications and to aid in secondary treatment planning.

Endovascular device design in the future: transformation from trial and error to computational design

Endovascular devices have been designed by trial and error, with bench and animal testing followed by human clinical trials to determine whether the devices are safe and effective. Despite remarkable advances over the past 15 years, there are persistent concerns regarding the long-term durability of endovascular devices. This may be due to deficiencies in device design, which has lagged behind other industries in adopting computational methods that are now routinely used to design, develop, and test new aircraft and automobiles. Similar computational design and failure mode simulations that evaluate performance under stress conditions have not been widely applied in the development of endovascular devices. Advances in medical imaging and computational modeling now allow simulation of physiological conditions in patient-specific 3-dimensional vascular models, which can provide a framework to design and test the next generation of endovascular devices. This modeling will allow the prospective design of devices that can withstand the force variations in the cardiovascular system that occur during bending, coughing, and varying degrees of exercise, as well as the extremes encountered during sudden impact in contact sports. Utilization of computational design methodology that takes into consideration the physiology of the cardiovascular system will improve future endovascular devices so that they are safer and more effective and durable.

Large infra-renal abdominal aortic aneurysms: endovascular vs. open repair--single centre experience

Endovascular aneurysm repair (EVAR) has become an established alternative to open repair (OR). We present a consecutive series of 486 elective patients with large infra-renal aortic abdominal aneurysm, comparing OR with EVAR. Prospective data collected during an 8-year period from January 1997 to October 2005 was reviewed. Statistical analysis performed using SPSS data editor with chi(2) tests and Mann-Whitney U-tests. There were 486 patients with 329 OR (293 males, 36 females) with median age of 72 years with median diameter 6.3 cm and 157 EVAR (148 males, 9 females) with median age 75 years with median diameter 6.1 cm. Mortality was 13 (4%) for OR and 5 (3.2%) for EVAR (three of whom were in the UK EVAR 2 trial). Blood loss was significantly less for EVAR 500 ml vs. 1500 ml for OR. Sixty-five (19.8%) patients with OR had significantly more peri-operative complications compared with 14 (8.9%) with EVAR. The length of stay in hospital was significantly less for EVAR. This non-randomised study shows that although EVAR does not have a statistically significantly lower mortality, it does have statistically significantly lower complication rates compared with OR. EVAR can be achieved with good primary success, but long-term follow-up is essential to assess durability.

Screening and ultrasound surveillance of large abdominal aortic aneurysms do not improve suitability for endovascular repair

OBJECTIVE

The effect of population screening for abdominal aortic aneurysm (AAA) disease on morbidity and mortality has been comprehensively studied and reported. However, the effect of early AAA detection on suitability for endovascular aneurysm repair (EVAR) remains unknown. Considering the importance of such an effect on future health economics, we sought to assess the possible effect of AAA ultrasound surveillance on suitability for EVAR.

METHODS

This was a prospective cohort study. From January 2002 to August 2003, consecutive AAA patients selected for open elective repair were placed into one of two groups according to mode of presentation. The first group included patients referred from a local well-established AAA ultrasound screening and surveillance program (ultrasound surveillance [AAA-S] group). The second group included patients referred from neighboring unscreened regions with incidentally diagnosed AAA (incidental [AAA-I] group). All patients underwent preoperative computed tomographic angiography. By using three-dimensional reconstruction software, computed tomographic images were assessed by two blinded observers for suitability for EVAR by using the criteria for a modular endovascular device.

RESULTS

Of 74 patients included in the study, 41 were in the AAA-S group, and 31 were in the AAA-I group. The median aneurysm diameter was 72.3 mm (range, 50.7-83.7 mm) for AAA-I and 65 mm (range, 50.7-79.2 mm) for AAA-S (P < .47). Suitability for EVAR was 41% in the AAA-S group and 45% in the AAA-I group (P < .47).

CONCLUSIONS

Early detection and surveillance of AAA does not seem to increase suitability for EVAR. Suitability for EVAR seems to be determined early on in an aneurysm's life. On the basis of current device technology, referral for intervention from an AAA surveillance program may need to be initiated at a size well below 5.5 cm if an increase in EVAR suitability is to be expected.

Endovascular Repair of Thoracic and Abdominal Aortic Aneurysms: Pre- and Postprocedural Imaging

Endovascular repair of thoracic and abdominal aortic aneurysms is a safe alternative to conventional open surgical repair. Clinical success, however, is highly dependent on patient selection. Diagnostic vascular imaging has an essential role for this selection process. Following endovascular aneurysm repair (EVAR), patients require long-term surveillance and again vascular imaging serves an integral function. This article reviews EVAR selection criteria and post-EVAR assessment and then discusses the imaging modalities used to evaluate these patients, namely multi-detector-row computed tomographic angiography, magnetic resonance imaging/angiography, duplex ultrasonography, and catheter angiography.