Three-Dimensional Geometric Analysis of Viabahn VBX Bridging Stent Grafts in Fenestrated Endovascular Aortic Repair: A Multicenter, Retrospective Cohort Study

PURPOSE

The primary aim of this study was to assess the 3-dimensional flare geometry of the Gore Viabahn VBX balloon-expandable covered stent (BECS) after fenestrated endovascular aortic repair (FEVAR) and to determine and visualize BECS-associated complications.

METHODS

This multicenter retrospective study included patients who underwent FEVAR between 2018 and 2022 in 3 vascular centers participating in the VBX Expand Registry. Patients with at least one visceral artery treated with the VBX and with availability of 2 post-FEVAR computed tomography angiography (CTA) scans (follow-up [FU] 1: 0-6 months; FU2: 9-24 months) were included. The flare geometry of the VBX, including flare-to-fenestration distance, flare-to-fenestration diameter ratio, flare angle, and apposition with the target artery were assessed using a vascular workstation and dedicated CTA applied software.

RESULTS

In total, 90 VBX BECS were analyzed in 43 FEVAR patients. The median CTA FU for FU1 and FU2 was 35 days (interquartile range [IQR], 29-51 days) and 14 months (IQR, 13-15 months), respectively. The mean flare-to-fenestration distance was 5.6±2.0 mm on FU1 and remained unchanged at 5.7±2.0 mm on FU2 (p=.417). The flare-to-fenestration diameter ratio was 1.19±0.17 on FU1 and remained unchanged at 1.21±0.19 (p=.206). The mean apposition length was 18.6±5.3 mm on FU1 and remained 18.6±5.3 mm (p=.550). The flare angle was 31°±15° on FU1 and changed to 33°±16° (p=.009). On FU1, the BECS-associated complication rate was 1%, and the BECS-associated reintervention rate was 0%. On FU2, the BECS-associated complication rate was 3%, and the BECS-associated reintervention rate was 1%.

CONCLUSIONS

The flare geometry of the VBX bridging stent did not change significantly during 14 months follow-up in this study. Three-dimensional geometric analysis of the flare may contribute to identify the origin of endoleaks and occlusions, but this should be confirmed in a larger study including enough patients and BECS to compare complicated and uncomplicated cases.

CLINICAL IMPACT

The three-dimensional flare geometry of the Gore Viabahn VBX BECS was assessed on the first and second postoperative CTA scans, and geometrical changes during this period were identified. For BECS that were diagnosed with a type 3c endoleak or occlusion, the BECS geometry was analyzed to detect geometrical components that were related to the complication. Geometric analysis of the flare may help to better detect and identify the cause of such complications.

Geometric Analysis of the Gore Excluder Conformable Endoprosthesis in the Infrarenal Aortic Neck: One Year Results of the EXCeL Registry

OBJECTIVE

The Gore Excluder Conformable Endoprosthesis (CEXC) is designed to treat challenging infrarenal anatomy because of its active angulation control, repositionability, and enhanced conformability. This study evaluated 30 day and one year position and apposition of the CEXC in the infrarenal neck.

METHODS

Patients treated with the CEXC between 2018 and 2022 with an available 30 day computed tomography angiography (CTA) were selected from four hospitals in a prospective registry. Endograft apposition (shortest apposition length [SAL]) and position (shortest fabric distance [SFD]) were assessed on the 30 day and one year CTAs. Maximum infrarenal aortic curvature was compared between the pre-operative and post-operative CTAs to evaluate conformability of the CEXC.

RESULTS

There were 87 patients with a 30 day CTA, and for 56 of these patients the one year CTA was available. Median (interquartile range [IQR]) pre-operative neck length was 22 mm (IQR 15, 32) and infrarenal angulation was 52° (IQR 31, 72). Median SAL was 21.2 mm (IQR 14.0, 29.3) at 30 days for all included patients. The SAL in 13 patients (15%) was < 10 mm at 30 days, and one patient had a SAL of 0 mm and a type Ia endoleak. There was no significant difference in SAL between patients within and outside instructions for use. The SAL significantly increased by 1.1 mm (IQR -2.3, 4.7; p = .042) at 1 year. The SAL decreased in seven patients (13%), increased in 13 patients (23%), and remained stable in 36 patients (64%). Median SFD was 2.0 mm (IQR 0.5, 3.6) at 30 days, which slightly increased by 0.3 mm (IQR -0.5, 1.8; p = .019) at 1 year. One patient showed migration (SFD increase ≥ 5 mm). Median endograft tilt was 15.8° (IQR 9.7, 21.4). Pre-operative maximum infrarenal curvature was 36 m-1 (IQR 26, 56) and did not significantly change thereafter.

CONCLUSION

In most patients, the CEXC was implanted close to the renal arteries, and sufficient (≥ 10 mm) post-operative apposition was acquired at 30 days, which slightly increased at one year. Post-operative endograft tilt was relatively low, and aortic geometry remained unchanged after implantation of the CEXC, probably due to its high conformability.

Position- and posture-dependent vascular imaging-a scoping review

OBJECTIVES

Position- and posture-dependent deformation of the vascular system is a relatively unexplored field. The goal of this scoping review was to create an overview of existing vascular imaging modalities in different body positions and postures and address the subsequent changes in vascular anatomy.

METHODS

Scopus, Medline, and Cochrane were searched for literature published between January 1, 2000, and June 30, 2022, incorporating the following categories: image modality, anatomy, orientation, and outcomes.

RESULTS

Out of 2446 screened articles, we included 108. The majority of papers used ultrasound (US, n = 74) in different body positions and postures with diameter and cross-sectional area (CSA) as outcome measures. Magnetic resonance imaging (n = 22) and computed tomography (n = 8) were less frequently used but allowed for investigation of other geometrical measures such as vessel curvature and length. The venous system proved more sensitive to postural changes than the arterial system, which was seen as increasing diameters of veins below the level of the heart when going from supine to prone to standing positions, and vice versa.

CONCLUSIONS

The influence of body positions and postures on vasculature was predominantly explored with US for vessel diameter and CSA. Posture-induced deformation and additional geometrical features that may be of interest for the (endovascular) treatment of vascular pathologies have been limitedly reported, such as length and curvature of an atherosclerotic popliteal artery during bending of the knee after stent placement. The most important clinical implications of positional changes are found in diagnosis, surgical planning, and follow-up after stent placement.

CLINICAL RELEVANCE STATEMENT

This scoping review presents the current state and opportunities of position- and posture-dependent imaging of vascular structures using various imaging modalities that are relevant in the fields of clinical diagnosis, surgical planning, and follow-up after stent placement.

KEY POINTS

• The influence of body positions and postures on the vasculature was predominantly investigated with US for vessel diameter and cross-sectional area. • Research into geometrical deformation, such as vessel length and curvature adaptation, that may be of interest for the (endovascular) treatment of vascular pathologies is limited in different positions and postures. • The most important clinical implications of postural changes are found in diagnosis, surgical planning, and follow-up after stent placement.

Health Literacy and Disease Knowledge of Patients With Peripheral Arterial Disease or Abdominal Aortic Aneurysm: A Scoping Review

OBJECTIVE

This scoping review summarises health literacy and disease knowledge in patients with abdominal aortic aneurysm (AAA) or peripheral arterial disease (PAD) and the influencing factors.

DATA SOURCES

A systematic search was conducted in PubMed, Embase, PsychINFO, and CINAHL covering the period January 2012 to October 2022.

REVIEW METHODS

This scoping review was undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Inclusion criteria encompassed studies addressing health literacy, knowledge, perception, or awareness in patients with AAA or PAD. Two authors independently reviewed abstracts and full texts, resolving any discrepancies through discussion or by consulting a third author for consensus. All article types were included except letters, editorials, study protocols, reviews, and guidelines. No language restrictions were applied. Primary outcomes were health literacy and disease knowledge. Secondary outcomes were factors that could influence this. Quality assessment was done using the Mixed Methods Appraisal Tool (MMAT).

RESULTS

The review included 32 articles involving a total of 5 268 patients. Four articles reported health literacy and the rest disease knowledge. Ten studies (31%) met all quality criteria. Twenty studies were quantitative, eight were qualitative, and four were mixed methods studies. The review revealed inadequate health literacy in the majority of patients, and disease knowledge was relatively low among patients with AAA and PAD, with disparities in measures and assessment tools across studies. Factors influencing health literacy and disease knowledge included socioeconomic status, education, income, and employment.

CONCLUSION

This scoping review revealed low health literacy and low disease knowledge in patients with AAA and PAD. Standardised health literacy assessment may contribute to improve communication strategies and decision aids to enhance patients' understanding and engagement in healthcare decisions, however further research is needed to prove its merits.

Endograft position and endoleak detection after endovascular abdominal aortic repair with low-field tiltable MRI: a feasibility study

BACKGROUND

Abdominal aortic endoleaks after endovascular aneurysm repair might be position-dependent, therefore undetectable using supine imaging. We aimed to determine the feasibility and benefit of using a low-field tiltable magnetic resonance imaging (MRI) scanner allowing to study patients who can be imaged in both supine and upright positions of endoleaks.

METHODS

Ten EVAR patients suspected of endoleak based on ultrasound examination were prospectively included. MRI in upright and supine positions was compared with routine supine computed tomography angiography (CTA). Analysis was performed through (1) subjective image quality assessment by three observers, (2) landmark registration between MRI and CTA scans, (3) Euclidean distances between renal and endograft landmarks, and (4) evaluation of endoleak detection on MRI by a consensus panel. Statistical analysis was performed by one-way repeated measures analysis of variance.

RESULTS

The image quality of upright/supine MRI was inferior compared to CTA. Median differences in both renal and endograft landmarks were approximately 6-7 mm between upright and supine MRI and 5-6 mm between supine MRI and CTA. In the proximal sealing zone of the endograft, no differences were found among all three scan types (p = 0.264). Endoleak detection showed agreement between MRI and CTA in 50% of the cases, with potential added value in only one patient.

CONCLUSIONS

The benefit of low-field upright MRI for endoleak detection was limited. While MRI assessment was non-inferior to standard CTA in detecting endoleaks in selected cases, improved hardware and sequences are needed to explore the potential of upright MRI in patients with endoleaks.

RELEVANCE STATEMENT

Upright low-field MRI has limited clinical value in detecting position-dependent endoleaks; improvements are required to fulfil its potential as a complementary modality in this clinical setting.

KEY POINTS

• Upright MRI shows potential for imaging endoleaks in aortic aneurysm patients in different positions. • The image quality of upright MRI is inferior to current techniques. • Upright MRI complements CTA, but lacks accurate deformation measurements for clinical use. • Advancements in hardware and imaging sequences are needed to fully utilise upright MRI capabilities.

Carotid calcium burden derived from computed tomography angiography as a predictor of all-cause mortality after carotid endarterectomy

OBJECTIVE

Carotid endarterectomy (CEA) aims to reduce the risk of stroke in patients with atherosclerotic carotid disease. Preoperative risk assessments that predict complications are needed to optimize the care in this patient group. The current approach, namely relying solely on symptomatology and degree of stenosis, is outdated and calls for innovation. The Agatston calcium score was applied in several vascular specialties to assess cardiovascular risk profile but has been little studied in carotid surgery. It is hypothesized that a higher calcium burden at initial presentation equates to a worse prognosis attributable to an increased cerebrovascular and cardiovascular risk profile. The aim was to investigate the association between preoperative ipsilateral calcium score and postoperative all-cause mortality in patients undergoing CEA.

METHODS

This single-center retrospective cohort study included 89 patients who underwent CEA at a tertiary referral center between 2010 and 2018. Preoperative calcium scores were measured on contrast-enhanced computed tomography images with patient-specific Hounsfield thresholds at the level of the carotid bifurcation. The association between these calcium scores and all-cause mortality was analyzed using multivariable adjusted Cox proportional hazard analysis.

RESULTS

Cox proportional hazard analysis demonstrated a significant association between preoperative ipsilateral carotid calcium score and all-cause mortality (hazard ratio, 1.10; 95% confidence interval, 1.03-1.16; P = .003). After adjusting for age, preoperative estimated glomerular filtration rate, and diabetes mellitus, a significant association remained (hazard ratio, 1.07; 95% confidence interval, 1.00-1.15; P = .05).

CONCLUSIONS

A higher calcium burden was predictive of worse outcome, which might be explained by an overall poorer health status. These results highlight the potential of calcium measurements in combination with other traditional risk factors, for preoperative risk assessment and thus for improved patient education and care.

Clinical Applications of Conebeam CTP Imaging in Cerebral Disease: A Systematic Review

BACKGROUND

Perfusion imaging with multidetector CT is integral to the evaluation of patients presenting with ischemic stroke due to large-vessel occlusion. Using conebeam CT perfusion in a direct-to-angio approach could reduce workflow times and improve functional outcome.

PURPOSE

Our aim was to provide an overview of conebeam CT techniques for quantifying cerebral perfusion, their clinical applications, and validation.

DATA SOURCES

A systematic search was performed for articles published between January 2000 and October 2022 in which a conebeam CT imaging technique for quantifying cerebral perfusion in human subjects was compared against a reference technique.

STUDY SELECTION

Eleven articles were retrieved describing 2 techniques: dual-phase (n = 6) and multiphase (n = 5) conebeam CTP.

DATA ANALYSIS

Descriptions of the conebeam CT techniques and the correlations between them and the reference techniques were retrieved.

DATA SYNTHESIS

Appraisal of the quality and risk of bias of the included studies revealed little concern about bias and applicability. Good correlations were reported for dual-phase conebeam CTP; however, the comprehensiveness of its parameter is unclear. Multiphase conebeam CTP demonstrated the potential for clinical implementation due to its ability to produce conventional stroke protocols. However, it did not consistently correlate with the reference techniques.

LIMITATIONS

The heterogeneity within the available literature made it impossible to apply meta-analysis to the data.

CONCLUSIONS

The reviewed techniques show promise for clinical use. Beyond evaluating their diagnostic accuracy, future studies should address the practical challenges associated with implementing these techniques and the potential benefits for different ischemic diseases.

Implementing Wearable Sensors for Clinical Application at a Surgical Ward: Points to Consider before Starting

Incorporating technology into healthcare processes is necessary to ensure the availability of high-quality care in the future. Wearable sensors are an example of such technology that could decrease workload, enable early detection of patient deterioration, and support clinical decision making by healthcare professionals. These sensors unlock continuous monitoring of vital signs, such as heart rate, respiration rate, blood oxygen saturation, temperature, and physical activity. However, broad and successful application of wearable sensors on the surgical ward is currently lacking. This may be related to the complexity, especially when it comes to replacing manual measurements by healthcare professionals. This report provides practical guidance to support peers before starting with the clinical application of wearable sensors in the surgical ward. For this purpose, the Non-Adoption, Abandonment, Scale-up, Spread, and Sustainability (NASSS) framework of technology adoption and innovations in healthcare organizations is used, combining existing literature and our own experience in this field over the past years. Specifically, the relevant topics are discussed per domain, and key lessons are subsequently summarized.

Diminishing Endograft Apposition during Follow-Up Is an Important Indicator of Late Type 1a Endoleak after Endovascular Aneurysm Repair

Late type 1a endoleaks (T1aELs) after endovascular aneurysm repair (EVAR) are hazardous complications which should be avoided. This study investigated the evolution of the shortest apposition length (SAL) post-EVAR and hypothesised that a declining apposition during follow-up may be an indicator of T1aEL development. Patients with a late T1aEL were selected from a consecutive multicentre database. For each T1aEL patient, the preoperative computed tomography angiography (CTA), first postoperative CTA, and pre-endoleak CTA were analysed. T1aEL patients were matched 1:1 to uncomplicated controls, based on endograft type and follow-up duration. Anatomical characteristics and endograft dimensions, including the post-EVAR SAL, were measured. Included were 28 patients with a late T1aEL and 28 matched controls. The SAL decreased from 11.2 mm (5.6-20.6 mm) to 3.9 mm (0.0-11.4 mm) in the T1aEL group (p = 0.006), whereas an increase in SAL was seen in the control group from 21.3 mm (14.1-25.8 mm) to 25.4 mm (19.0-36.2 mm; p = 0.015). On the pre-endoleak CTA, 18 patients (64%) in the T1aEL group had a SAL < 10 mm, and one (4%) patient in the control group had a SAL < 10 mm on the matched CTAs. Moreover, three mechanisms of decreasing sealing zone were identified, which might be used to determine optimal imaging or reintervention strategies. Diminishing SAL < 10 mm is an indicator for T1aEL during follow-up, it is imperative to include apposition analysis during follow-up.

Validation of a Length-Adjusted Abdominal Arterial Calcium Score Method for Contrast-Enhanced CT Scans

BACKGROUND

The Agatston score on noncontrast computed tomography (CT) scans is the gold standard for calcium load determination. However, contrast-enhanced CT is commonly used for patients with atherosclerotic cardiovascular diseases (ASCVDs), such as peripheral arterial occlusive disease (PAOD) and abdominal aortic aneurysm (AAA). Currently, there is no validated method to determine calcium load in the aorta and peripheral arteries with a contrast-enhanced CT. This study validated a length-adjusted calcium score (LACS) method for contrast-enhanced CT scans.

METHOD

The LACS (calcium volume in mm³/arterial length in cm) in the abdominal aorta was calculated using four-phase liver CT scans of 30 patients treated between 2017 and 2021 at the University Medical Center Groningen (UMCG) with no aortic disease. Noncontrast CT scans were segmented with a 130 Hounsfield units (HU) threshold, and a patient-specific threshold was used for contrast-enhanced CTs. The LACS was calculated and compared from both segmentations. Secondly, the interobserver variability and the influence of slice thickness (0.75 mm vs. 2.0 mm) was determined.

RESULTS

There was a high correlation between the LACS from contrast-enhanced CT scans and the LACS of noncontrast CTs (R² = 0.98). A correction factor of 1.9 was established to convert the LACS derived from contrast-enhanced CT to noncontrast CT scans. LACS interobserver agreement on contrast-enhanced CT was excellent (1.0, 95% confidence interval = 1.0-1.0). The 0.75 mm CT threshold was 541 (459-625) HU compared with 500 (419-568) HU on 2 mm CTs (p = 0.15). LACS calculated with both thresholds was not significantly different (p = 0.63).

CONCLUSION

The LACS seems to be a robust method for scoring calcium load on contrast-enhanced CT scans in arterial segments with various lengths.

Development of a Statistical Shape Model and Assessment of Anatomical Shape Variations in the Hemipelvis

Knowledge about anatomical shape variations in the pelvis is mandatory for selection, fitting, positioning, and fixation in pelvic surgery. The current knowledge on pelvic shape variation mostly relies on point-to-point measurements on 2D X-ray images and computed tomography (CT) slices. Three-dimensional region-specific assessments of pelvic morphology are scarce. Our aim was to develop a statistical shape model of the hemipelvis to assess anatomical shape variations in the hemipelvis. CT scans of 200 patients (100 male and 100 female) were used to obtain segmentations. An iterative closest point algorithm was performed to register these 3D segmentations, so a principal component analysis (PCA) could be performed, and a statistical shape model (SSM) of the hemipelvis was developed. The first 15 principal components (PCs) described 90% of the total shape variation, and the reconstruction ability of this SSM resulted in a root mean square error of 1.58 (95% CI: 1.53-1.63) mm. In summary, an SSM of the hemipelvis was developed, which describes the shape variations in a Caucasian population and is able to reconstruct an aberrant hemipelvis. Principal component analyses demonstrated that, in a general population, anatomical shape variations were mostly related to differences in the size of the pelvis (e.g., PC1 describes 68% of the total shape variation, which is attributed to size). Differences between the male and female pelvis were most pronounced in the iliac wing and pubic rami regions. These regions are often subject to injuries. Future clinical applications of our newly developed SSM may be relevant for SSM-based semi-automatic virtual reconstruction of a fractured hemipelvis as part of preoperative planning. Lastly, for companies, using our SSM might be interesting in order to assess which sizes of pelvic implants should be produced to provide proper-fitting implants for most of the population.

A Statistical Shape Model of Infrarenal Aortic Necks in Patients With and Without Late Type Ia Endoleak After Endovascular Aneurysm Repair

PURPOSE

Hostile aortic neck characteristics, including short length, severe suprarenal and infrarenal angulation, conicity, and large diameter, have been associated with increased risk for type Ia endoleak (T1aEL) after endovascular aneurysm repair (EVAR). This study investigates the mid-term discriminative ability of a statistical shape model (SSM) of the infrarenal aortic neck morphology compared with or in combination with conventional measurements in patients who developed T1aEL post-EVAR.

MATERIALS AND METHODS

The dataset composed of EVAR patients who developed a T1aEL during follow-up and a control group without T1aEL. Principal component (PC) analysis was performed using a parametrization to create an SSM. Three logistic regression models were created. To discriminate between patients with and without T1aEL, sensitivity, specificity, and the area under the receiver operating characteristic (ROC) curve (AUC) were calculated.

RESULTS

In total, 126 patients (84% male) were included. Median follow-up time in T1aEl group and control group was 52 (31, 78.5) and 51 (40, 62.5) months, respectively. Median follow-up time was not statistically different between the groups (p=0.72). A statistically significant difference between the median PC scores of the T1aEL and control groups was found for the first, eighth, and ninth PC. Sensitivity, specificity, and AUC values for the SSM-based versus the conventional measurements-based logistic regression models were 79%, 70%, and 0.82 versus 74%, 73%, and 0.85, respectively. The model of the SSM and conventional measurements combined resulted in sensitivity, specificity, and AUC of 81%, 81%, and 0.92.

CONCLUSION

An SSM of the infrarenal aortic neck determines its 3-dimensional geometry. The SSM is a potential valuable tool for risk stratification and T1aEL prediction in EVAR. The SSM complements the conventional measurements of the individual preoperative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleak after standard EVAR.

CLINICAL IMPACT

A statistical shape model (SSM) determines the 3-dimensional geometry of the infrarenal aortic neck. The SSM complements the conventional measurements of the individual pre-operative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleaks post-EVAR. The SSM is a potential valuable tool for risk stratification and late T1aEL prediction in EVAR and it is a first step toward implementation of a treatment planning support tool in daily clinical practice.

Validation of an ex vivo Flow Model Including Magnetic Resonance Imaging to Study the Effects of Endovascular Treatments on the Arterial Wall

Endovascular revascularization is the preferred treatment for peripheral arterial disease. Restenosis often occurs as a response to procedure-induced arterial damage. Reducing vascular injury during endovascular revascularization may improve its success rate. This study developed and validated an ex vivo flow model using porcine iliac arteries, obtained from a local abattoir. Twenty arteries (of 10 pigs) were equally allocated to two groups: a mock-treated control group and an endovascular intervention group. Arteries of both groups were perfused with porcine blood for 9 min, including 3 min of balloon angioplasty in the intervention group. Vessel injury was assessed by calculating the presence of endothelial cell denudation, vasomotor function, and histopathological analysis. MR imaging displayed balloon positioning and inflation. Endothelial cell staining showed 76% of denudation after ballooning compared to 6% in the control group (p < 0.001). This was confirmed by histopathological analysis, showing a significantly reduced endothelial nuclei count after ballooning compared to the controls (median: 22 vs. 37 nuclei/mm, p = 0.022). In the intervention group, vasoconstriction and endothelium-dependent relaxation were significantly reduced (p < 0.05).We present an ex vivo flow model to test the effects of endovascular therapy on the vessel's wall morphology, endothelial denudation, and endothelial-dependent vasomotor function under physiological conditions. Additionally, it allows the future testing of human arterial tissue.

Clinical Applications of Quantitative Perfusion Imaging with a C-Arm Flat-Panel Detector-A Systematic Review

C-arm systems with digital flat-panel detectors are used in interventional radiology and hybrid operating rooms for visualizing and performing interventions on three-dimensional structures. Advances in C-arm technology have enabled intraoperative quantitative perfusion imaging with these scanners. This systematic review provides an overview of flat-panel detector C-arm techniques for quantifying perfusion, their clinical applications, and their validation. A systematic search was performed for articles published between January 2000 and October 2022 in which a flat-panel detector C-arm technique for quantifying perfusion was compared with a reference technique. Nine articles were retrieved describing two techniques: two-dimensional perfusion angiography (n = 5) and dual-phase cone beam computed tomography perfusion (n = 4). A quality assessment revealed no concerns about the applicability of the studies. The risk of bias was relatively high for the index and reference tests. Both techniques demonstrated potential for clinical application; however, weak-to-moderate correlations were reported between them and the reference techniques. In conclusion, both techniques could add new possibilities to treatment planning and follow-up; however, the available literature is relatively scarce and heterogeneous. Larger-scale randomized prospective studies focusing on clinical outcomes and standardization are required for the full understanding and clinical implementation of these techniques.

Determining the Reliable Measurement Period for Preoperative Baseline Values With Telemonitoring Before Major Abdominal Surgery: Pilot Cohort Study

BACKGROUND

Preoperative telemonitoring of vital signs, physical activity, and well-being might be able to optimize prehabilitation of the patient's physical and mental condition prior to surgery, support setting alarms during in-hospital monitoring, and allow personalization of the postoperative recovery process.

OBJECTIVE

The primary aim of this study was to evaluate when and how long patients awaiting major abdominal surgery should be monitored to get reliable preoperative individual baseline values of heart rate (HR), daily step count, and patient-reported outcome measures (PROMs). The secondary aim was to describe the perioperative course of these measurements at home.

METHODS

In this observational single-center cohort study, patients used a wearable sensor during waking hours and reported PROMs (pain, anxiety, fatigue, nausea) on a tablet twice a day. Intraclass correlation coefficients (ICCs) were used to evaluate the reliability of mean values on 2 specific preoperative days (the first day of telemonitoring and the day before hospital admission) and randomly selected preoperative periods compared to individual reference values. Mean values of HR, step count, and PROMs per day were visualized in a boxplot from 14 days before hospital admission until 30 days after surgery.

RESULTS

A total of 16 patients were included in the data analyses. The ICCs of mean values on the first day of telemonitoring were 0.91 for HR, 0.71 for steps, and at least 0.86 for PROMs. The day before hospital admission showed reliability coefficients of 0.76 for HR, 0.71 for steps, and 0.92-0.99 for PROMs. ICC values of randomly selected measurement periods increased over the continuous period of time from 0.68 to 0.99 for HR and daily step counts. A lower bound of the 95% CI of at least 0.75 was determined after 3 days of measurements. The ICCs of randomly selected PROM measurements were 0.89-0.94. Visualization of mean values per day mainly showed variable preoperative daily step counts (median 2409, IQR 1735-4661 steps/day) and lower postoperative daily step counts (median 884, IQR 474-1605 steps/day). In addition, pain was visually reduced until 30 days after surgery at home.

CONCLUSIONS

In this prospective pilot study, for patients awaiting major abdominal surgery, baseline values for HR and daily step count could be measured reliably by a wearable sensor worn for at least 3 consecutive days and PROMs during any preoperative day. No clear conclusions were drawn from the description of the perioperative course by showing mean values of HR, daily step count, and PROM values over time in the home situation.

Determination of Changes in Tissue Perfusion at Home with Hyperspectral and Thermal Imaging in the First Six Weeks after Endovascular Therapy in Patients with Peripheral Arterial Disease

The aims of this study were to assess changes in tissue perfusion up to 6 weeks after endovascular therapy (EVT), in hospital and at home, and to determine differences in tissue perfusion between patients with and without clinical improvement or good angiographic result. This single-center prospective cohort study included patients undergoing EVT for Rutherford stages two to six. Hyperspectral and thermal imaging were performed at the dorsal and plantar sides of the foot. These measurements consisted of a baseline measurement pre-EVT, and six follow-up measurements obtained at 1 and 4 h and 6 weeks in hospital, and 1 day, 7 days, and 14 days at home. Clinical improvement was defined as a decrease of one or more Rutherford class or decrease in the wound surface area and a good angiographic result was accomplished when a Transatlantic Inter-Society Consensus for the Management of PAD II C or D lesion was treated and uninterrupted flow continued in at least one below-the-knee artery in continuation with the inframalleolar arteries. The study included 34 patients with 41 treated limbs. Deoxyhemoglobin values were lower 1 h post-EVT compared with baseline and increased over time up to 6 weeks post-EVT. Significant differences in deoxyhemoglobin levels at 7 and 14 days post-EVT were determined between patients with and without clinical or angiographic success. This prospective pilot study shows the feasibility of hyperspectral imaging and thermal imaging post-EVT at home, which may decrease the need for hospital visits.

Feasibility and patient's experiences of perioperative telemonitoring in major abdominal surgery: an observational pilot study

BACKGROUND

Telemonitoring during the perioperative trajectory may improve patient outcomes and self-management. The aim of this study is to assess the feasibility of and patient's experiences with telemonitoring before and after major abdominal surgery to inform future study design.

METHODS

Patients planned for elective major abdominal surgery wore a sensor and answered well-being questions on a tablet daily for at least 2 weeks preoperatively up to 30-days postoperatively. Feasibility was assessed by participation and completion rate, compliance per day, weekly satisfaction scores, and reasons for nonscheduled contact.

RESULTS

Twenty-three patients were included (participation rate of 54.5%) with a completion rate of 69.6%. Median compliance with the wearable sensor and well-being questions was respectively: 94.7% and 83.3% preoperatively at home; 100% and 66.7% postoperatively in-hospital; and 95.4% and 85.8% postoperatively at home. Median weekly satisfaction scores for both wearing the sensor and well-being questions were 5 (IQR, 4-5). Contact moments were related to absence of sensor data and technological issues (76.0%) or patient discomfort and insecurity (24.0%).

CONCLUSIONS

In this study, telemonitoring showed high satisfaction and compliance during the perioperative trajectory. Future trial design regarding the effectiveness of telemonitoring requires embedding in clinical practice and support for patients, relatives, and healthcare personnel.

Laser Doppler Flowmetry Combined with Spectroscopy to Determine Peripheral Tissue Perfusion and Oxygen Saturation: A Pilot Study in Healthy Volunteers and Patients with Peripheral Arterial Disease

Background: In this study, we assessed the ability of the EPOS system (Perimed AB, Järfälla, Stockholm, Sweden) to detect differences in tissue perfusion between healthy volunteers and patients with peripheral arterial disease (PAD) with different severity of disease. Methods: This single-center prospective pilot study included 10 healthy volunteers and 20 patients with PAD scheduled for endovascular therapy (EVT). EPOS measurements were performed at rest at 32 °C and 44 °C, followed by transcutaneous oxygen pressure (TcPo₂) measurements. The measurements were performed on the dorsal and medial side of the foot, as well as the lateral side of the calf. EPOS parameters included hemoglobin oxygen saturation (HbSo₂) and speed-resolved red blood cell (RBC) perfusion. Results: HbSo₂ at 44 °C was significantly different between the three groups for all measurement locations. The overall speed-resolved RBC perfusion at 44 °C was statistically significant between the groups on the dorsal and medial side of the foot but not on the calf. TcPo₂ values were not significantly different between the three groups. Conclusions: This study demonstrates that the EPOS system can depict differences in tissue perfusion between healthy volunteers, patients with Fontaine class IIb PAD, and those with Fontaine class III or IV PAD but only after heating to 44 °C.

Detecting Changes in Tissue Perfusion With Hyperspectral Imaging and Thermal Imaging Following Endovascular Treatment for Peripheral Arterial Disease

PURPOSE

Hyperspectral imaging (HSI) and thermal imaging allow contact-free tissue perfusion measurements and may help determine the effect of endovascular treatment (EVT) in patients with peripheral arterial disease. This study aimed to detect changes in perfusion with HSI and thermal imaging peri-procedurally and determine whether these changes can identify limbs that show clinical improvement after 6 weeks.

METHODS

Patients with Rutherford class 2-6 scheduled for EVT were included prospectively. Hyperspectral imaging and thermal imaging were performed directly before and after EVT. Images were taken from the lateral side of the calves and plantar side of the feet. Concentrations of (de)oxyhemoglobin, oxygen saturation, and skin temperature were recorded. Angiographic results were determined on completion angiogram. Clinical improvement 6 weeks after EVT was defined as a decrease ≥ one Rutherford class. Peri-procedural changes in perfusion parameters were compared between limbs with and without good angiographic results or clinical improvement. To identify limbs with clinical improvement, receiver operating characteristic (ROC) curves were used to determine cutoff values for change in HSI.

RESULTS

Included were 23 patients with 29 treated limbs. Change in HSI values and temperature was not significantly different between limbs with good and poor angiographic results. Change in peri-procedural deoxyhemoglobin, determined by HSI, at the calves and feet was significantly different between limbs with and without clinical improvement at 6 week follow-up (p=0.027 and p=0.017, respectively). The ROC curve for change in deoxyhemoglobin at the calves showed a cutoff value of ≤1.0, and ≤-0.5 at the feet, which were discriminative for clinical improvement (sensitivity 77%; specificity 75% and sensitivity 62%; specificity 88%, respectively).

CONCLUSIONS

HSI can detect changes in perfusion at the calves after EVT in patients with Rutherford class 2-6. Peri-procedural deoxyhemoglobin changes at the calves and feet are significantly different between limbs with and without clinical improvement. Decrease in deoxyhemoglobin directly after EVT may identify limbs that show clinical improvement 6 weeks after EVT.

In Vitro Geometry Analysis of Fenestrations in Endovascular Aneurysm Repair

PURPOSE

Changes in the flared end of balloon-expandable covered stent (BECS) may precede BECS-associated complications but are not regularly assessed with computed tomographic angiography (CTA) after fenestrated endovascular aneurysm repair (FEVAR). Validation of the flare geometric analysis (FGA) and assessment of intraobserver and interobserver variability are investigated in this study.

METHODS

Two series of 3 BeGraft BECSs (Bentley InnoMed GmbH, Hechingen, Germany) and 1 series of 3 Advanta V12 BECSs (Getinge AB, Göteborg, Sweden) were deployed in 3 side branches (45°, 60°, and 90° aortic branch angles) of an aorta phantom model. A standard post-FEVAR CTA scan was acquired. Computed tomographic angiography-derived measurements consisted of centerline reconstructions and placement of 3-dimensional coordinate markers by 2 observers in a vascular workstation. Flare geometric analysis calculates 3 BECS parameters: the circumferential flare-to-fenestration distance (FFD), which is the distance from the proximal end of the flare to fenestration, and diameters at the proximal end of the flare (Dflare) and at the fenestration (Dfenestration). Computed tomographic angiography-derived measurements were validated against microscopy measurements. Bland-Altman plots were used to determine the intraobserver and interobserver variability of the BECS parameters and intraclass correlation coefficient (ICC).

RESULTS

For each BECS, the FFD at 4 equidistant quadrants of the circumference, Dflare, and Dfenestration were calculated. The mean difference and repeatability coefficient (RC) of the validation were 0.8 (2.1) mm for FFD, 0.4 (1.0) mm for Dflare, and -0.2 (1.2) mm for Dfenestration. The mean intraobserver and interobserver difference (RC) was 0.5 (1.6) mm and 0.7 (2.6) mm for FFD, 0.1 (0.6) mm and 0.1 (0.7) mm for Dflare, and -0.1 (0.8) mm and -0.8 (1.0) mm for Dfenestration. The mean ICC of intraobserver variability was 0.86 for FFD, 0.94 for Dflare, and 0.78 for Dfenestration. The mean ICC of interobserver variability was 0.77 for FFD, 0.92 for Dflare, and 0.48 for Dfenestration.

CONCLUSION

This study showed that FGA of the flared ends of BECS can be performed with high accuracy in a phantom model, with good intraobserver and interobserver variability. Flare geometric analysis can be used to determine flare geometry of the BECS on standard post-FEVAR CTA scans.

Continuous Monitoring of Vital Signs With Wearable Sensors During Daily Life Activities: Validation Study

Background

Continuous telemonitoring of vital signs in a clinical or home setting may lead to improved knowledge of patients’ baseline vital signs and earlier detection of patient deterioration, and it may also facilitate the migration of care toward home. Little is known about the performance of available wearable sensors, especially during daily life activities, although accurate technology is critical for clinical decision-making.

Objective

The aim of this study is to assess the data availability, accuracy, and concurrent validity of vital sign data measured with wearable sensors in volunteers during various daily life activities in a simulated free-living environment.

Methods

Volunteers were equipped with 4 wearable sensors (Everion placed on the left and right arms, VitalPatch, and Fitbit Charge 3) and 2 reference devices (Oxycon Mobile and iButton) to obtain continuous measurements of heart rate (HR), respiratory rate (RR), oxygen saturation (SpO₂), and temperature. Participants performed standardized activities, including resting, walking, metronome breathing, chores, stationary cycling, and recovery afterward. Data availability was measured as the percentage of missing data. Accuracy was evaluated by the median absolute percentage error (MAPE) and concurrent validity using the Bland-Altman plot with mean difference and 95% limits of agreement (LoA).

Results

A total of 20 volunteers (median age 64 years, range 20-74 years) were included. Data availability was high for all vital signs measured by VitalPatch and for HR and temperature measured by Everion. Data availability for HR was the lowest for Fitbit (4807/13,680, 35.14% missing data points). For SpO₂ measured by Everion, median percentages of missing data of up to 100% were noted. The overall accuracy of HR was high for all wearable sensors, except during walking. For RR, an overall MAPE of 8.6% was noted for VitalPatch and that of 18.9% for Everion, with a higher MAPE noted during physical activity (up to 27.1%) for both sensors. The accuracy of temperature was high for VitalPatch (MAPE up to 1.7%), and it decreased for Everion (MAPE from 6.3% to 9%). Bland-Altman analyses showed small mean differences of VitalPatch for HR (0.1 beats/min [bpm]), RR (−0.1 breaths/min), and temperature (0.5 °C). Everion and Fitbit underestimated HR up to 5.3 (LoA of −39.0 to 28.3) bpm and 11.4 (LoA of −53.8 to 30.9) bpm, respectively. Everion had a small mean difference with large LoA (−10.8 to 10.4 breaths/min) for RR, underestimated SpO₂ (>1%), and overestimated temperature up to 2.9 °C.

Conclusions

Data availability, accuracy, and concurrent validity of the studied wearable sensors varied and differed according to activity. In this study, the accuracy of all sensors decreased with physical activity. Of the tested sensors, VitalPatch was found to be the most accurate and valid for vital signs monitoring.

Continuous monitoring of vital signs with the Everion biosensor on the surgical ward: a clinical validation study

BACKGROUND

Wearable sensors enable continuous vital sign monitoring, although information about their performance on nursing wards is scarce. Vital signs measured by telemonitoring and nurse measurements on a surgical ward were compared to assess validity and reliability.

METHODS

In a prospective observational study, surgical patients wore a wearable sensor (Everion, Biovotion AG, Zürich, Switzerland) that continuously measured heart rate (HR), respiratory rate (RR), oxygen saturation (SpO₂), and temperature during their admittance on the ward. Validity was evaluated using repeated-measures correlation and reliability using Bland-Altman plots, mean difference, and 95% limits of agreement (LoA).

RESULTS

Validity analyses of 19 patients (median age, 68; interquartile range, 62.5-72.5 years) showed a moderate relationship between telemonitoring and nurse measurements for HR (r = 0.53; 95% confidence interval, 0.44-0.61) and a poor relationship for RR, SpO₂, and temperature. Reliability analyses showed that Everion measured HR close to nurse measurements (mean difference, 1 bpm; LoA, -16.7 to 18.7 bpm). Everion overestimated RR at higher values, whereas SpO₂ and temperature were underestimated.

CONCLUSIONS

A moderate relationship was determined between Everion and nurse measurements at a surgical ward in this study. Validity and reliability of telemonitoring should also be assessed with gold standard devices in future clinical trials.

Outcomes of Advanta V12 Covered Stents After Fenestrated Endovascular Aneurysm Repair

Purpose:

Fenestrated endovascular aneurysm repair (FEVAR) is a well-established endovascular treatment option for pararenal abdominal aortic aneurysms in which balloon-expandable covered stents (BECS) are used to bridge the fenestration to the target vessels. This study presents midterm clinical outcomes and patency rates of the Advanta V12 BECS used as a bridging stent.

Methods:

All patients treated with FEVAR with at least 1 Advanta V12 BECS were included from 2 large-volume vascular centers between January 2012 and December 2015. Primary endpoints were freedom from all-cause reintervention, and freedom from BECS-associated complications and reintervention. BECS-associated complications included significant stenosis, occlusion, type 3 endoleak, or stent fracture. Secondary endpoints included all-cause mortality in-hospital and during follow-up.

Results:

This retrospective study included 194 FEVAR patients with a mean age of 72.2±8.0 years. A total of 457 visceral arteries were stented with an Advanta V12 BECS. Median (interquartile range) follow-up time was 24.6 (1.6, 49.9) months. The FEVAR procedure was technically successful in 93% of the patients. Five patients (3%) died in-hospital. Patient survival was 77% (95% CI 69% to 84%) at 3 years. Freedom from all-cause reintervention was 70% (95% CI 61% to 78%) at 3 years, and 33% of all-cause reinterventions were BECS associated. Complications were seen in 24 of 457 Advanta V12 BECSs: type 3 endoleak in 8 BECSs, significant stenosis in 4 BECSs, occlusion in 6 BECSs, and stent fractures in 3 BECSs. A combination of complications occurred in 3 BECSs: type 3 endoleak and stenosis, stent fracture and stenosis, and stent fracture and occlusion. The freedom from BECS-associated complications for Advanta V12 BECSs was 98% (95% CI 96% to 99%) at 1 year and 92% (95% CI 88% to 95%) at 3 years. The freedom from BECS-associated reinterventions was 98% (95% CI 95% to 100%) at 1 year and 94% (95% CI 91% to 97%) at 3 years.

Conclusion:

The Advanta V12 BECS used as bridging stent in FEVAR showed low complication and reintervention rates at 3 years. A substantial number of FEVAR patients required a reintervention, but most were not BECS related.

Reliability assessment of hyperspectral imaging with the HyperView™ system for lower extremity superficial tissue oxygenation in young healthy volunteers

Purpose: Hyperspectral imaging (HSI) is a noninvasive spectroscopy technique for determining superficial tissue oxygenation. The HyperView™ system is a hand-held camera that enables perfusion image acquisition. The evaluation of superficial tissue oxygenation is warranted in the evaluation of patients with peripheral arterial disease. The aim was to determine the reliability of repeated HSI measurements. Methods: In this prospective cohort study, HSI was performed on 50 healthy volunteers with a mean age of 26.4 ± 2.5 years, at the lower extremity. Two independent observers performed HSI during two subsequent measurement sessions. Short term test–retest reliability and intra- and inter-observer reliability were determined, and generalizability and decision studies were performed. Transcutaneous oxygen pressure (TcPo₂) measurements were also performed. Results: The short term test–retest reliability was good for the HSI values determined at the lower extremity, ranging from 0.72 to 0.90. Intra- and inter-observer reliability determined at different days were poor to moderate for both HSI (0.24 to 0.71 and 0.30 to 0.58, respectively) and TcPo₂ (0.54 and 0.56, and 0.51 and 0.31, respectively). Reliability can be increased to >0.75 by averaging two measurements on different days. Conclusion: This study showed good short term test–retest reliability for HSI measurements, however low intra- and inter-observer reliability was observed for tissue oxygenation measurements with both HSI and TcPo₂ performed at separate days in young healthy volunteers. Reliability of HSI can be improved when determined as a mean of two measurements taken on different days.

Remodeling of Abdominal Aortic Angulation and Curvature After Endovascular Aneurysm Repair in Patients With vs Without Late Type Ia Endoleak or Endograft Migration

PURPOSE

To investigate aortic remodeling of the supra- and infrarenal aorta from preoperative to 1 month and midterm follow-up after endovascular aneurysm repair (EVAR) by analyzing changes in angulation and curvature in patients with vs without late type Ia endoleak or device migration.

MATERIALS AND METHODS

From a multicenter database, 35 patients (mean age 76±5 years; 31 men) were identified with late (>1 year) type Ia endoleak or endograft migration (≥10 mm) and defined as the complication group. The control group consisted of 53 patients (mean age 75±7 years; 48 men) with >1-year computed tomography angiography (CTA) follow-up and no evidence of endoleaks. Suprarenal and infrarenal angles were measured on centerline reconstructions of the preoperative, 1-month, and midterm CTA scans. The value and location relative to baseline of maximum suprarenal and infrarenal curvature were determined semiautomatically using dedicated software. Changes were determined at 1 month compared with the preoperative CTA and at midterm compared with 1 month.

RESULTS

Preoperative suprarenal angulation was significantly greater in the complication group compared to the controls (34°±18° vs 24°±17°, p=0.008). It decreased significantly at 1 month in the complication group (29°±16°, p=0.011) and at midterm follow-up in the controls (20°±19°, p<0.001). Preoperative infrarenal angulation was not significantly different (57°±15° vs 49°±24°, p=0.114). This measurement increased significantly through midterm follow-up in the complication group (63°±23°, p<0.001) but remained stable in the controls (46°±22°). Preoperative suprarenal curvature was not significantly different (38±22 m^-1 vs 29±25 m^-1, p=0.115). This variable increased significantly through midterm follow-up in the complication group (44±22 m^-1) but remained constant in the controls (28±22 m^-1). Preoperative infrarenal curvature was significantly greater in the complication group (77±29 m^-1 vs 65±28 m^-1, p=0.047) and decreased significantly in both groups during midterm follow-up (50±17 m^-1 vs 41±19 m^-1 p=0.033). The location of the maximum curvature with regard to baseline shifted significantly distally in the complication group (54±43 to 72±41 mm, p<0.001), while it remained stable in the controls (46±33 to 48±31 mm).

CONCLUSION

At midterm follow-up, significant differences in supra- and infrarenal angulation and curvature were observed between patients with vs without type Ia endoleak or migration. The location of the maximum curvature shifted distally in patients with complications. The aortic morphology is more stable during midterm follow-up in the patients without endoleaks.

Changes in Apposition of Endograft Limbs in the Iliac Arteries After Endovascular Aneurysm Repair: Determination With New Computed Tomography-Applied Software

Purpose: To validate new computed tomography (CT)-applied software used to determine endograft limb position and apposition after endovascular aneurysm repair (EVAR). Materials and Methods: Twelve EVAR patients (mean age 81±6 years; 10 men) with distal stent-graft extensions for 15 (3 bilateral) type Ib endoleaks during follow-up were selected based on the availability of the following CT studies: pre-EVAR, 1 month, and the penultimate scan prior to the scan disclosing the type Ib endoleak. Twelve patients (mean age 82±7 years; 11 men) without endoleak and a similar interval between the primary EVAR procedure and the penultimate CT scan of the endoleak group were selected as controls using measurements from both endograft limbs (n=21, 3 excluded). Prototype Vascular Imaging Analysis software was adapted to calculate 6 parameters for the distal apposition zone: fabric distance, shortest apposition length, endograft diameter, iliac seal surface (ISS), iliac endograft apposition surface (IEAS), and percentage of iliac surface coverage (IEAS/ISS × 100). Measurements were performed on the preoperative, first postoperative, and penultimate/matched follow-up CT scans. Interobserver variability was assessed with the intraclass correlation coefficient (ICC). Continuous data are presented as the median [interquartile range (IQR) Q1, Q3]. Results: CTA follow-up was not significantly different between the endoleak and control groups [30 months (IQR 18, 58) vs 36 months (IQR 21, 59), p=0.843]. Interobserver agreement was good to excellent for all parameters (ICC 0.879-0.985). Preoperative anatomy and endograft dimensions on the first follow-up CTA scan did not differ significantly between the groups. When the penultimate CTA scan was compared with the first postoperative CT scan, endograft dimensions had significantly changed in the endoleak group; importantly, apposition was significantly decreased, and fabric distance was significantly increased, indicating limb retraction. Differences in changes in endograft dimensions were significant between the groups. Conclusion: New CT-applied software was introduced to visualize apposition and position changes of endograft limbs during follow-up. The software demonstrated good-to-excellent interobserver agreement and enabled accurate analysis of post-EVAR endograft dimensions. Significant changes in apposition and position were observed with the software on the penultimate CT scan prior to diagnosis of type Ib endoleak.

Telemedicine in patients with peripheral arterial disease: is it worth the effort?

Introduction: For patients with peripheral arterial disease (PAD), the various components of telemedicine, such as telemonitoring, telecoaching, and teleconsultation, could be valuable in daily management. The objective of this review was to give an overview of the current use of telemedicine interventions in PAD. Areas covered: A literature search was performed for studies that evaluated patients with PAD of the aorto-pedal trajectory, who were monitored by telemedicine and acted upon accordingly. The primary outcome was health-related outcomes. The studies that were found focused mainly on wearable activity monitoring and telecoaching in PAD (n = 4) or wound monitoring after vascular surgery (n = 2). Main results indicate that telemedicine interventions are able to detect (post-operative) complications early, improve functional capacity and claudication onset time, and improve PAD patients' quality of life. Expert opinion: The use of telemedicine in PAD patients is still an under-explored area. Studies investigating the use of telemedicine in PAD are very limited and show varying results. Owing to its high potential in improving physical ability, lifestyle coaching, and timely detection of deterioration, future research should focus on proper implementation of telemedicine in PAD patients, including clinical and feasibility outcomes, effect on workload of nurses, and cost-efficiency.

A systematic review of diagnostic techniques to determine tissue perfusion in patients with peripheral arterial disease

Introduction: Peripheral arterial disease (PAD) may cause symptoms due to impaired tissue perfusion of the lower extremity. So far, assessment of PAD is mainly performed by determination of stenosis or occlusion in the large arteries and does not focus on microcirculation. Several diagnostic techniques have been recently introduced that may enable tissue perfusion measurements in the lower limb; however, most have not yet been implemented in clinical daily practice. This systematic review provides an overview of these diagnostic techniques and their ability to accurately detect PAD by peripheral tissue perfusion. Areas covered: A literature search was performed for articles that described a diagnostic technique to determine tissue perfusion in patients with known PAD compared with healthy controls. Expert opinion: So far, transcutaneous oxygen measurements are most often used to measure tissue oxygenation in PAD patients, but evidence seems too low to define this technique as a gold standard, and implementing this technique for home monitoring is difficult. New potentially suitable diagnostic tests should be non-invasive, contact-free, and quick. Further research is needed for all of these techniques before broad implementation in clinical use is justified, in hospital, and for home monitoring.

A New Methodology to Determine Apposition, Dilatation, and Position of Endografts in the Descending Thoracic Aorta After Thoracic Endovascular Aortic Repair

Purpose: To validate computed tomography angiography (CTA)–applied software to assess apposition, dilatation, and position of endografts in the proximal and distal landing zones after thoracic endovascular aortic repair (TEVAR) of thoracic aortic aneurysm. Materials and Methods: Twenty-two patients (median age 75.5 years; 11 men) with a degenerative descending thoracic aortic aneurysm treated with TEVAR with at least one postoperative CTA were selected from a single center’s database. New CTA-applied software was used to determine the available apposition surface in the proximal and distal landing zones, apposition of the endograft fabric with the aortic wall, shortest apposition length, endograft inflow and outflow diameters, shortest distance between the left subclavian artery and the proximal endograft fabric, and shortest distance between the celiac trunk and the distal endograft fabric on each CTA. Interobserver variability for these parameters was assessed with the repeatability coefficient and the intraclass correlation coefficient. Results: Excellent interobserver agreement was found for all measurements. Interobserver variability of surface and shortest apposition length calculations was larger for the distal site compared with the proximal site, with a mean difference of 10% vs 2% of the mean available apposition surface, 12% vs 5% of the endograft apposition surface, and 16% vs 8% of the shortest apposition length, respectively. Inflow and outflow diameters of the endograft showed low variability, with a mean difference of 0.1 mm with 95% of the interobserver difference within 1.8 mm. Mean interobserver differences of the proximal and distal shortest fabric distances were 1.0 and 0.9 mm (both 2% of the mean lengths). Conclusion: Assessment of apposition, dilatation, and position of the proximal and distal parts of an endograft in the descending thoracic aorta is feasible after TEVAR with the new software. Interobserver agreement for all measured parameters was excellent for the proximal and distal landing zones. The new method allows detection of subtle changes during follow-up. However, a larger study is needed to quantify how parameters change over time in complicated and uncomplicated TEVAR cases and to define the real added value of the new methodology.

Anatomical Predictors of Endoleaks or Migration After Endovascular Aneurysm Sealing

Purpose: To identify preoperative anatomical aortic characteristics that predict seal failures after endovascular aneurysm sealing (EVAS) and compare the incidence of events experienced by patients treated within vs outside the instructions for use (IFU). Methods: Of 355 patients treated with the Nellix EndoVascular Aneurysm Sealing System (generation 3SQ+) at 3 high-volume centers from March 2013 to December 2015, 94 patients were excluded, leaving 261 patients (mean age 76±8 years; 229 men) for regression analysis. Of these, 83 (31.8%) suffered one or more of the following events: distal migration ⩾5 mm of one or both stent frames, any endoleak, and/or aneurysm growth >5 mm. Anatomical characteristics were determined on preoperative computed tomography (CT) scans. Patients were divided into 3 groups: treated within the original IFU (n=166), outside the original IFU (n=95), and within the 2016 revised IFU (n=46). Categorical data are presented as the median (interquartile range Q1, Q3). Results: Neck diameter was significantly larger in the any-event cohort vs the control cohort [23.7 mm (21.7, 26.3) vs 23.0 mm (20.9, 25.2) mm, p=0.022]. Neck length was significantly shorter in the any-event cohort [15.0 mm (10.0, 22.5) vs 19.0 mm (10.0, 21.8), p=0.006]. Maximum abdominal aortic aneurysm (AAA) diameter and the ratio between the maximum AAA diameter and lumen diameter in the any-event group were significantly larger than the control group (p=0.041 and p=0.002, respectively). Regression analysis showed aortic neck diameter (p=0.006), neck length (p=0.001), and the diameter ratio (p=0.011) as significant predictors of any event. In the comparison of events to IFU status, 52 (31.3%) of 166 patients in the inside the original IFU group suffered an event compared to 13 (28.3%) of 46 patients inside the 2016 IFU group (p=0.690). Conclusion: Large neck diameter, short aortic neck length, and the ratio between the maximum AAA and lumen diameters are preoperative anatomical predictors of the occurrence of migration (⩾5 mm), any endoleak, and/or aneurysm growth (>5 mm) after EVAS. Even under the refined 2016 IFU, more than a quarter of patients suffered from an event. Improvements in the device seem to be necessary before this technique can be implemented on a large scale in endovascular AAA repair.

Apposition and Positioning of the Nellix EndoVascular Aneurysm Sealing System in the Infrarenal Aortic Neck

PURPOSE

To investigate the initial proximal position and seal of the Nellix EndoVascular Aneurysm Sealing (EVAS) system in the aortic neck using a novel methodology.

METHODS

Forty-six consecutive patients who underwent elective EVAS for an abdominal aortic aneurysm were retrospectively selected and dichotomized into an early (n=23) and a late (n=23) group. The aortic neck morphology and aortic neck surface (ANS) were determined on preoperative computed tomography (CT) scans; the endograft position and nonapposition surface (NAS) were determined on the 1-month CT scans. The position of the proximal endobag boundary was measured by 2 experienced observers to analyze the interobserver variability for the EVAS NAS measurements. The shortest distance from the lowest renal artery to the endobag (shortest fabric distance) and the shortest distance from the endobag to the end of the infrarenal neck (shortest sealing distance) were determined. The intraclass correlation coefficients (ICCs) are presented with the 95% confidence interval (CI). Continuous data are presented as the median and interquartile range (IQR: Q3 - Q1).

RESULTS

There were no differences between the early and late EVAS groups regarding aortic neck morphology except for the neck calcification circumference [41° (IQR 33°) vs 87° (IQR 60°), respectively; p=0.043]. Perfect agreement was observed for the NAS (ICC 0.897, 95% CI 0.780 to 0.956). The NAS as a percentage of the preoperative ANS was 47% (IQR 43) vs 49% (IQR 49) for the early vs late groups, respectively (p=0.214). The shortest fabric distances were 5 mm (IQR 5) and 4 mm (IQR 7) for the early and late groups, respectively (p=0.604); the shortest sealing distances were 9 mm (IQR 13) and 16 mm (IQR 17), respectively (p=0.066).

CONCLUSION

Accurate positioning of the Nellix EVAS system in the aortic neck may be challenging. Despite considerable experience with the system, still around half of the potential seal in the aortic neck was missed in the current series, without improvement over time. This should be considered during preoperative planning and may be a cause of a higher than expected complication rate. Detailed post-EVAS nonapposition surface can be determined with the described novel methodology that takes into account the sometimes irregularly shaped top of the sealing endobags.

Validation of a New Methodology to Determine 3-Dimensional Endograft Apposition, Position, and Expansion in the Aortic Neck After Endovascular Aneurysm Repair

Purpose: To validate a novel methodology employing regular postoperative computed tomography angiography (CTA) scans to assess essential factors contributing to durable endovascular aneurysm repair (EVAR), including endograft deployment accuracy, neck adaptation to radial forces, and effective apposition of the fabric within the aortic neck. Methods: Semiautomatic calculation of the apposition surface between the endograft and the infrarenal aortic neck was validated in vitro by comparing the calculated surfaces over a cylindrical silicon model with known dimensions on CTA reconstructions with various slice thicknesses. Interobserver variabilities were assessed for calculating endograft position, apposition, and expansion in a retrospective series of 24 elective EVAR patients using the repeatability coefficient (RC) and the intraclass correlation coefficient (ICC). The variability of these calculations was compared with variability of neck length and diameter measurements on centerline reconstructions of the preoperative and first postoperative CTA scans. Results: In vitro validation showed accurate calculation of apposition, with deviation of 2.8% from the true surface for scans with 1-mm slice thickness. Excellent agreement was achieved for calculation of the endograft dimensions (ICC 0.909 to 0.996). Variability was low for calculation of endograft diameter (RC 2.3 mm), fabric distances (RC 5.2 to 5.7 mm), and shortest apposition length (RC 4.1 mm), which was the same as variability of regular neck diameter (RC 0.9 to 1.1 mm) and length (RC 4.0 to 8.0 mm) measurements. Conclusion: This retrospective validation study showed that apposition surfaces between an endograft and the infrarenal neck can be calculated accurately and with low variability. Determination of the (ap)position of the endograft in the aortic neck and detection of subtle changes during follow-up are crucial to determining eventual failure after EVAR.

The BeGraft Balloon Expandable Covered Stent as a Proximal Extension to an Iliac Branch Device for Endovascular Repair of Isolated Common Iliac Artery Aneurysms

Introduction

Isolated common iliac artery aneurysms (CIAA) are rare and can be treated by endovascular exclusion using iliac branch devices (IBD). The use of a balloon expandable covered stent as a proximal extension to an IBD to allow adequate sealing in the proximal common iliac artery (CIA) for exclusion of isolated CIAA is demonstrated.

Report

Two patients with isolated CIAA of ≥4.5 cm with a proximal neck length of ≥20 mm (patient A: 26 mm; patient B: 24 mm) and a neck diameter of ≤20 mm (patient A: 16.4 mm; patient B: 15.6 mm) were treated by combining a Zenith IBD with an aortic BeGraft balloon expandable covered stent. After deploying the BeGraft covered stent at 12 mm a second balloon was used to further dilate the proximal part of the stent outside the IBD to allow adequate sealing in the CIA. Completion angiography and follow up computed tomography angiography 1 month post-operatively showed adequate sealing and no endoleaks.

Discussion

The feasibility of the application of a balloon expandable covered stent as a proximal extension to an IBD for isolated CIAA was demonstrated. It is not necessary to insert an aortic bifurcation endograft, thus reducing procedure time, radiation exposure, contrast use, and cost. A patent inferior mesenteric artery and lumbar arteries can be spared and procedures that require crossing over the aortic bifurcation remain possible. Comorbidity, prior interventions, and disease extension can make this endovascular approach preferred over open repair. Isolated CIAA can be efficiently treated combining the BeGraft balloon expandable covered stent and IBD, which allows proximal sealing in the CIA.

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Isolated common iliac artery aneurysms are rare.

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A balloon expandable covered stent can be used as proximal extension to iliac branch devices.

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This allows adequate sealing in the common iliac artery.

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This approach allows a simplified procedure with reduced procedure time, radiation exposure, contrast use, and cost.

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Crossover procedures across the iliac bifurcation remain possible and inferior mesenteric and lumbar arteries are spared.

Determination of Endograft Apposition, Position, and Expansion in the Aortic Neck Predicts Type Ia Endoleak and Migration After Endovascular Aneurysm Repair

Purpose: To describe the added value of determining changes in position and apposition on computed tomography angiography (CTA) after endovascular aneurysm repair (EVAR) to detect early caudal displacement of the device and to prevent type Ia endoleak. Methods: Four groups of elective EVAR patients were selected from a dataset purposely enriched with type Ia endoleak and migration (>10 mm) cases. The groups included cases of late type Ia endoleak (n=36), migration (n=9), a type II endoleak (n=16), and controls without post-EVAR complications (n=37). Apposition of the endograft fabric with the aortic neck, shortest distance between the fabric and the renal arteries, expansion of the main body (or dilatation of the aorta in the infrarenal sealing zone), and tilt of the endograft toward the aortic axis were determined on the first postoperative and the last available CTA scan without type Ia endoleak or migration. Differences in these endograft dimensions were compared between the first vs last scan and among the 4 groups. Results: No significant differences in endograft configurations were observed among the groups on the first postoperative CTA scan. On the last CTA scan before a complication arose, the position of the fabric relative to the renal arteries, expansion of the main body, and apposition of the fabric with the aortic neck were significantly different between the type Ia endoleak (median follow-up 15 months) and migration groups (median follow-up 23 months) compared with the control group (median follow-up 19 months). Most endograft dimensions had changed significantly compared with the first postoperative CTA scan for all groups. Apposition had increased in the control group but had decreased significantly in the type Ia endoleak and migration groups. Conclusion: Progressive changes in dimensions of the endograft within the infrarenal neck could be detected on regular CTA scans before the complication became urgent in many patients.

A Semiautomated Method for Measuring the 3-Dimensional Fabric to Renal Artery Distances to Determine Endograft Position After Endovascular Aneurysm Repair

Purpose: To report a methodology for 3-dimensional (3D) assessment of the stent-graft deployment accuracy after endovascular aneurysm repair (EVAR). Methods: A methodology was developed and validated to calculate the 3D distances between the endograft fabric and the renal arteries over the curve of the aorta. The shortest distance between one of the renal arteries and the fabric (SFD) and the distance from the contralateral renal artery to the fabric (CFD) were determined on the first postoperative computed tomography (CT) scan of 81 elective EVAR patients. The SFDs were subdivided into a target position (0–3 mm distal to the renal artery), high position (partially covering the renal artery), and low position (>3 mm distal to the renal artery). Data are reported as the median (interquartile range, IQR). Results: Intra- and interobserver agreements for automatic and manual calculation of the SFD and CFD were excellent (ICC >0.892, p<0.001). The median SFD was 1.4 mm (IQR −0.9, 3.0) and the median CFD was 8.0 mm (IQR 3.9, 14.2). The target position was achieved in 44%, high position in 30%, and low position in 26% of the patients. The median slope of the endograft toward the higher renal artery was 2.5° (IQR −5.5°, 13.9°). Conclusion: The novel methodology using 3D CT reconstructions enables accurate evaluation of endograft position and slope within the proximal aortic neck. In this series, only 44% of endografts were placed within the target position with regard to the lowermost renal artery.

Aortic Curvature Is a Predictor of Late Type Ia Endoleak and Migration After Endovascular Aneurysm Repair

Purpose: To evaluate the association between aortic curvature and other preoperative anatomical characteristics and late (>1 year) type Ia endoleak and endograft migration in endovascular aneurysm repair (EVAR) patients. Methods: Eight high-volume EVAR centers contributed 116 EVAR patients (mean age 81±7 years; 103 men) to the study: 36 patients (mean age 82±7 years; 31 men) with endograft migration and/or type Ia endoleak diagnosed >1 year after the initial EVAR and 80 controls without early or late complications. Aortic curvature was calculated from the preoperative computed tomography scan as the maximum and average curvature over 5 predefined aortic segments: the entire infrarenal aortic neck, aneurysm sac, and the suprarenal, juxtarenal, and infrarenal aorta. Other morphological characteristics included neck length, neck diameter, mural neck calcification and thrombus, suprarenal and infrarenal angulation, and largest aneurysm sac diameter. Independent risk factors were identified using backward stepwise logistic regression. Relevant cutoff values for each of the variables in the final regression model were determined with the receiver operator characteristic curve. Results: Logistic regression identified maximum curvature over the length of the aneurysm sac (>47 m−1; p=0.023), largest aneurysm sac diameter (>56 mm; p=0.028), and mural neck thrombus (>11° circumference; p<0.001) as independent predictors of late migration and type Ia endoleak. Conclusion: Aortic curvature is a predictor for late type Ia endoleak and endograft migration after EVAR. These findings suggest that aortic curvature is a better parameter than angulation to predict post-EVAR failure and should be included as a hostile neck parameter.

Classification of gutter type in parallel stenting during endovascular aortic aneurysm repair

OBJECTIVE

Gutters can be described as the loss of continuous apposition between the main body of the endograft, the chimney stent graft, and the aortic wall. Gutters have been associated with increased risk of type IA endoleaks and are considered to be the Achilles' heel of chimney endovascular aneurysm repair (ch-EVAR). However, there is no classification yet to classify and quantify gutter types after ch-EVAR.

METHODS

Different gutter types can be distinguished by their morphologic appearance in two- and three-dimensional views and reconstructed slices perpendicular to the center lumen line.

RESULTS

Three main categories are defined by (1) the most proximal beginning of the gutter, (2) the length of gutter alongside the endograft, and (3) its distal end. Type A gutters originate at the proximal fabric of an endograft, type B gutters originate as loss of apposition of the chimney stent graft in the branch vessel, and type C gutters start below the fabric of the endograft. To determine eventual changes of gutter size during follow-up computed tomography angiograms (CTAs), measurements may be performed with dedicated software on the follow-up CTA scan to assess the extent of gutters over the aortic circumference, ranging from 0° to 360° of freedom, together with the maximum gap between the endograft material and the aortic wall as it appears on reconstructed axial CTA scan slices.

CONCLUSIONS

The proposed gutter classification enables a uniform nomenclature in the current ch-EVAR literature and a more accurate risk assessment of gutter-associated endoleaks. Moreover, it allows monitoring of eventual progression of gutter size during follow-up.