The CathEye: A Forward-Looking Ultrasound Catheter for Image-Guided Cardiovascular Procedures.

Catheter based procedures are typically guided by X-Ray, which suffers from low soft tissue contrast and only provides 2D projection images of a 3D volume. Intravascular ultrasound (IVUS) can serve as a complementary imaging technique. Forward viewing catheters are useful for visualizing obstructions along the path of the catheter. The CathEye system mechanically steers a single-element transducer to generate a forward-looking surface reconstruction from an irregularly spaced 2-D scan pattern. The steerable catheter leverages an expandable frame with cables to manipulate the distal end independently of vessel tortuosity. The tip position is estimated by measuring the cable displacements and used to create surface reconstructions of the imaging workspace with the single-element transducer. CathEye's imaging capabilities were tested with an agar phantom and an ex vivo chronic total occlusion (CTO) sample while the catheter was confined to various tortuous paths. The CathEye maintained similar scan patterns regardless of path tortuosity and was able to recreate major features of the imaging targets, such as holes and extrusions. The feasibility of forward-looking IVUS with the CathEye is demonstrated in this study. The CathEye mechanism can be applied to other imaging modalities with field-of-view (FOV) limitations and represents the basis for an interventional device fully integrated with image guidance.

The CathCam: A Novel Angioscopic Solution for Endovascular Interventions.

Peripheral arterial diseases are commonly managed with endovascular procedures, which often face limitations in device control and visualization under X-ray fluoroscopy guidance. In response, we developed the CathCam, an angioscope integrated into an expandable cable-driven parallel mechanism to enhance real-time visualization, precise device positioning and catheter support for successful plaque crossing. The primary objective of this study was to assess and compare the performance of the novel CathCam with respect to conventional catheters and the CathPilot (i.e., CathCam without the angioscope), for applications in crossing chronic total occlusions (CTO). We first assessed the system in 3D-printed phantom models, followed by an ex vivo evaluation with CTO samples from a patient's superficial femoral artery. We measured and compared success rates, crossing times, and fluoroscopy times in both experiments. The CathCam demonstrated a 100% success rate in phantom experiments and a 75% success rate in ex vivo experiments with CTO samples, compared to conventional catheters, with 35% and 25% success rates, respectively. The average crossing times for the CathCam and the conventional catheter were 31 s and 502 s for the phantom experiments and 210 s and 511 s for the actual CTO lesions. The Cathcam also showed to be a reliable endovascular imaging approach in an in vivo experiment. Compared to conventional catheters, the CathCam significantly increased the success rate and reduced crossing and fluoroscopy times in both phantom and ex vivo setups. CathCam can potentially improve clinical outcomes for minimally invasive endovascular interventions by offering high-resolution real-time imaging alongside accurate device control.

The CathPilot: Performance Validation and Preclinical Safety and Feasibility Assessment.

OBJECTIVES: Peripheral endovascular revascularization procedures often fail due to technical limitations of guidewire support, steering, and visualization. The novel CathPilot catheter aims to address these challenges. This study assesses the safety and feasibility of the CathPilot and compares its performance to conventional catheters for peripheral vascular interventions. METHODS: The study compared the CathPilot to non-steerable and steerable catheters. The success rates and access times for a relevant target inside a tortuous vessel phantom model were assessed. The reachable workspace within the vessel and the guidewire's force delivery capabilities were also evaluated. To validate the technology, chronic total occlusion tissue samples were used ex vivo to compare crossing success rates with conventional catheters. Finally, in vivo experiments in a porcine aorta were conducted to evaluate safety and feasibility. RESULTS: The success rates for reaching the set targets were 31%, 69%, and 100% with the non-steerable catheter, the steerable catheter, and the CathPilot, respectively. CathPilot had a significantly larger reachable workspace, and allowed for up to four times higher force delivery and pushability. In crossing of chronic total occlusion samples, the CathPilot achieved a success rate of 83% and 100%, for fresh and fixed lesions respectively, which was also significantly higher than conventional catheters. The device was fully functional in the in vivo study, and there were no signs of coagulation or damage to the vessel wall. CONCLUSION: This study shows the safety and feasibility of the CathPilot system and its potential to reduce failure and complication rates in peripheral vascular interventions. The novel catheter outperformed conventional catheters in all defined metrics. This technology can potentially improve the success rate and outcome of peripheral endovascular revascularization procedures.

General versus loco-regional anesthesia for endovascular aortic aneurysm repair.

BACKGROUND: Aortic aneurysms occur when the aorta, the body's largest artery, grows in size, and can occur in the thoracic or abdominal aorta. The approaches to repair aortic aneurysms include directly exposing the aorta and replacing the diseased segment via open repair, or endovascular repair. Endovascular repair uses fluoroscopic-guidance to access the aorta and deliver a device to exclude the aneurysmal aortic segment without requiring a large surgical incision. Endovascular repair can be performed under a general anesthetic, during which the unconscious patient is paralyzed and reliant on an anesthetic machine to maintain the airway and provide oxygen to the lungs, or a loco-regional anesethetic, for which medications are administered to provide the person with sufficient sedation and pain control without requiring a general anesthetic. While people undergoing general anesthesia are more likely to remain still during surgery and have a well-controlled airway in the event of unanticipated complications, loco-regional anesthesia is associated with fewer postoperative complications in some studies. It remains unclear which anesthetic technique is associated with better outcomes following the endovascular repair of aortic aneurysms. OBJECTIVES: To evaluate the benefits and harms of general anesthesia compared to loco-regional anesthesia for endovascular aortic aneurysm repair. SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search was 11 March 2022. SELECTION CRITERIA: We searched for all randomized controlled trials that assessed the effects of general anesthesia compared to loco-regional anesthesia for endovascular aortic aneurysm repairs. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were: all-cause mortality, length of hospital stay, length of intensive care unit stay. Our secondary outcomes were: incidence of endoleaks, requirement for re-intervention, incidence of myocardial infarction, quality of life, incidence of respiratory complications, incidence of pulmonary embolism, incidence of deep vein thrombosis, and length of procedure. We planned to use GRADE methodology to assess the certainty of evidence for each outcome. MAIN RESULTS: We found no studies, published or ongoing, that met our inclusion criteria. AUTHORS' CONCLUSIONS: We did not identify any randomized controlled trials that compared general versus loco-regional anesthesia for endovascular aortic aneurysm repair. There is currently insufficient high-quality evidence to determine the benefits or harms of either anesthetic approach during endovascular aortic aneurysm repair. Well-designed prospective randomized trials with relevant clinical outcomes are needed to adequately address this.

Experimental Protocol and Phantom Design and Development for Performance Characterization of Conventional Devices for Peripheral Vascular Interventions.

Conventional catheter-based interventions for treating peripheral artery disease suffer high failure and complication rates. The mechanical interactions with the anatomy constrain catheter controllability, while their length and flexibility limit their pushability. Also, the 2D X-ray fluoroscopy guiding these procedures fails to provide sufficient feedback about the device location relative to the anatomy. Our study aims to quantify the performance of conventional non-steerable (NS) and steerable (S) catheters in phantom and ex vivo experiments. In a 10 mm diameter, 30 cm long artery phantom model, with four operators, we evaluated the success rate and crossing time in accessing 1.25 mm target channels, the accessible workspace, and the force delivered through each catheter. For clinical relevance, we evaluated the success rate and crossing time in crossing ex vivo chronic total occlusions. For the S and NS catheters, respectively, users successfully accessed 69 and 31% of the targets, 68 and 45% of the cross-sectional area, and could deliver 14.2 and 10.2 g of mean force. Using a NS catheter, users crossed 0.0 and 9.5% of the fixed and fresh lesions, respectively. Overall, we quantified the limitations of conventional catheters (navigation, reachable workspace, and pushability) for peripheral interventions; this can serve as a basis for comparison with other devices.

A multicenter retrospective cohort study of blunt traumatic injury to the common or internal carotid arteries.

OBJECTIVE: Current EAST guidelines recommend against routine carotid intervention for patients with blunt carotid artery injury (BCI), but offer limited information on its role for BCI patients presenting with neurological deficit. Our goal was to describe the contemporary management and outcomes of patients presenting with BCI and neurological deficit unrelated to head injury. METHODS: We identified all adults who sustained a BCI between 2010 and 2017 in the American College of Surgeons Trauma Quality Improvement Program. We extracted patient demographics, injury characteristics (carotid and non-carotid), as well as the frequency, timing and approach of carotid intervention. Presence of neurological deficit unrelated to head injury at presentation was determined using Abbreviated Injury Scale codes. The main outcomes were in-hospital mortality and home discharge. Patients with and without neurological deficit at presentation were compared through multivariable logistic regression modeling. Among those with neurological deficit at presentation, the associations between carotid intervention (open or endovascular) and the outcomes were also assessed through multivariable logistic regression. RESULTS: We identified 5,788 patients with BCI of whom 383 (7%) presented with neurological deficit unrelated to head injury. Among the 296 patients (5%) who underwent carotid intervention, 36 (12%) had presented with neurological deficit unrelated to head injury. Interventions were most often endovascular (68% [200/296]) and within a median time of 32 h (IQR 5-203). In-hospital mortality was 16% (918/5,788), and in-hospital stroke prevalence was 6% (336/5,788). When comparing patients with and without neurological deficit at presentation, those with deficits were more frequently managed with an intervention. After adjustment, the likelihood of mortality was higher (OR [95% CI] = 2.16 [1.63-2.85]) and the likelihood of home discharge lower (OR [95% CI] = 0.29 [0.21-0.40]) among patients presenting with neurological deficit. Among those with neurological deficit, carotid intervention was positively associated with home discharge (OR [95% CI] = 2.96 [1.21-7.23]), but not with in-hospital mortality (OR [95% CI] = 0.87 [0.36-2.10]). Results were similar in the subgroup of patients with isolated BCI (2,971/5,788). CONCLUSIONS: Intervention in BCI patients presenting with neurological deficit may contribute to a greater likelihood of home discharge but not reduced in-hospital mortality.

Development of the Diabetic Wound Assessment Learning Tool (DiWALT) and validity evidence.

OBJECTIVE: Diabetic foot wounds account for up to one-third of diabetes-related health care expenditure and are the greatest cause of extremity amputation in Canada. Physicians encounter patients with such wounds in all specialties, particularly as generalists in medical wards and emergency departments. However, there is a dearth of literature on the optimal way to teach and to assess the management of these patients. Given the importance of assessment for learning in the shift toward competency-based medical education, we aimed to develop an assessment tool and to build validity evidence for its use in this context. METHODS: A consensus process involving nine Canadian experts in diabetic wound management was used to develop the Diabetic Wound Assessment Learning Tool (DiWALT) items and two 10-minute simulation-based testing scenarios. The simulators used were modified from commercially available models to serve the testing scenarios. Validity evidence for the DiWALT was subsequently evaluated by assessing 24 physician participants' performance during the two scenarios. All participants were novices (<50 cases managed). Two assessors independently rated participants using the DiWALT. Evidence was organized using Kane's validity framework and included Cronbach α for interitem consistency as well as test-retest and inter-rater reliability using the intra-class correlation coefficient (ICC). RESULTS: Cronbach α was 0.92, implying high internal consistency. Test-retest reliability was also excellent with ICC of 0.89 (confidence interval [CI], 0.76-0.95) for single measures and ICC of 0.94 (CI, 0.86-0.98) for average measures. Inter-rater reliability was fair for single measures with ICC of 0.68 (CI, 0.65-0.71) and good for average measures with ICC of 0.81 (CI, 0.79-0.83). CONCLUSIONS: These results demonstrate that the DiWALT consistently and reliably evaluates competence in diabetic wound management during simulated cases using a small, homogeneous sample of physicians. Further work is necessary to quantify sources of error in the assessment scores, to establish validity evidence when it is used to assess larger and more heterogeneous participants, and to identify how well the DiWALT differentiates between different experience levels.

Global Vascular Guidelines on the Management of Chronic Limb-Threatening Ischemia.

GUIDELINE SUMMARY: Chronic limb-threatening ischemia (CLTI) is associated with mortality, amputation, and impaired quality of life. These Global Vascular Guidelines (GVG) are focused on definition, evaluation, and management of CLTI with the goals of improving evidence-based care and highlighting critical research needs. The term CLTI is preferred over critical limb ischemia, as the latter implies threshold values of impaired perfusion rather than a continuum. CLTI is a clinical syndrome defined by the presence of peripheral artery disease (PAD) in combination with rest pain, gangrene, or a lower limb ulceration >2 weeks duration. Venous, traumatic, embolic, and nonatherosclerotic etiologies are excluded. All patients with suspected CLTI should be referred urgently to a vascular specialist. Accurately staging the severity of limb threat is fundamental, and the Society for Vascular Surgery Threatened Limb Classification system, based on grading of Wounds, Ischemia, and foot Infection (WIfI) is endorsed. Objective hemodynamic testing, including toe pressures as the preferred measure, is required to assess CLTI. Evidence-based revascularization (EBR) hinges on three independent axes: Patient risk, Limb severity, and ANatomic complexity (PLAN). Average-risk and high-risk patients are defined by estimated procedural and 2-year all-cause mortality. The GVG proposes a new Global Anatomic Staging System (GLASS), which involves defining a preferred target artery path (TAP) and then estimating limb-based patency (LBP), resulting in three stages of complexity for intervention. The optimal revascularization strategy is also influenced by the availability of autogenous vein for open bypass surgery. Recommendations for EBR are based on best available data, pending level 1 evidence from ongoing trials. Vein bypass may be preferred for average-risk patients with advanced limb threat and high complexity disease, while those with less complex anatomy, intermediate severity limb threat, or high patient risk may be favored for endovascular intervention. All patients with CLTI should be afforded best medical therapy including the use of antithrombotic, lipid-lowering, antihypertensive, and glycemic control agents, as well as counseling on smoking cessation, diet, exercise, and preventive foot care. Following EBR, long-term limb surveillance is advised. The effectiveness of nonrevascularization therapies (eg, spinal stimulation, pneumatic compression, prostanoids, and hyperbaric oxygen) has not been established. Regenerative medicine approaches (eg, cell, gene therapies) for CLTI should be restricted to rigorously conducted randomizsed clinical trials. The GVG promotes standardization of study designs and end points for clinical trials in CLTI. The importance of multidisciplinary teams and centers of excellence for amputation prevention is stressed as a key health system initiative.

Drug-eluting balloon angioplasty versus uncoated balloon angioplasty for the treatment of in-stent restenosis of the femoropopliteal arteries.

BACKGROUND: Stents are placed in the femoropopliteal arteries for numerous reasons, such as atherosclerotic disease, the need for dissection, and perforation of the arteries, and can become stenosed with the passage of time. When a stent develops a flow-limiting stenosis, this process is known as "in-stent stenosis." It is thought that in-stent restenosis is caused by a process known as "intimal hyperplasia" rather than by the progression of atherosclerotic disease. Management of in-stent restenosis may include performing balloon angioplasty, deploying another stent within the stenosed stent to force it open, and creating a bypass to deliver blood around the stent. The role of drug-eluting technologies, such as drug-eluting balloons (DEBs), in the management of in-stent restenosis is unclear. Drug-eluting balloons might function by coating the inside of stenosed stents with cytotoxic chemicals such as paclitaxel and by inhibiting the hyperplastic processes responsible for in-stent restenosis. It is important to perform this systematic review to evaluate the efficacy of DEB because of the potential for increased expenses associated with DEBs over uncoated balloon angioplasty, also known as plain old balloon angioplasty (POBA). OBJECTIVES: To assess the safety and efficacy of DEBs compared with uncoated balloon angioplasty in people with in-stent restenosis of the femoropopliteal arteries as assessed by criteria such as amputation-free survival, vessel patency, target lesion revascularization, binary restenosis rate, and death. We define "in-stent restenosis" as 50% or greater narrowing of a previously stented vessel by duplex ultrasound or angiography. SEARCH METHODS: The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to November 28, 2017. Review authors also undertook reference checking to identify additional studies. SELECTION CRITERIA: We included all randomized controlled trials that compared DEBs versus uncoated balloon angioplasty for treatment of in-stent restenosis in the femoropopliteal arteries. DATA COLLECTION AND ANALYSIS: Two review authors (AK, WA) independently selected appropriate trials and performed data extraction, assessment of trial quality, and data analysis. The senior review author (AD) adjudicated any disagreements. MAIN RESULTS: Three trials that randomized a combined total of 263 participants met the review inclusion criteria. All three trials examined the treatment of symptomatic in-stent restenosis within the femoropopliteal arteries. These trials were carried out in Germany and Austria and used paclitaxel as the agent in the drug-eluting balloons. Two of the three trials were industry sponsored. Two companies manufactured the drug-eluting balloons (Eurocor, Bonn, Germany; Medtronic, Fridley, Minnesota, USA). The trials examined both anatomical and clinical endpoints. We noted heterogeneity in the frequency of bailout stenting deployment between studies as well as in the dosage of paclitaxel applied by the DEBs. Using GRADE assessment criteria, we determined that the certainty of evidence presented was very low for the outcomes of amputation, target lesion revascularization, binary restenosis, death, and improvement of one or more Rutherford categories. Most participants were followed up to 12 months, but one trial followed participants for up to 24 months.Trial results show no difference in the incidence of amputation between DEBs and uncoated balloon angioplasty. DEBs showed better outcomes for up to 24 months for target lesion revascularization (odds ratio (OR) 0.05, 95% confidence Interval (CI) 0.00 to 0.92 at six months; OR 0.24, 95% CI 0.08 to 0.70 at 24 months) and at six and 12 months for binary restenosis (OR 0.28, 95% CI 0.14 to 0.56 at six months; OR 0.34, 95% CI 0.15 to 0.76 at 12 months). Participants treated with DEBs also showed improvement of one or more Rutherford categories at six and 12 months (OR 1.81, 95% CI 1.02 to 3.21 at six months; OR 2.08, 95% CI 1.13 to 3.83 at 12 months). Data show no clear differences in death between DEBs and uncoated balloon angioplasty. Data were insufficient for subgroup or sensitivity analyses to be conducted. AUTHORS' CONCLUSIONS: Based on a meta-analysis of three trials with 263 participants, evidence suggests an advantage for DEBs compared with uncoated balloon angioplasty for anatomical endpoints such as target lesion revascularization (TLR) and binary restenosis, and for one clinical endpoint - improvement in Rutherford category post intervention for up to 24 months. However, the certainty of evidence for all these outcomes is very low due to the small number of included studies and participants and the high risk of bias in study design. Adequately powered and carefully constructed randomized controlled trials are needed to adequately investigate the role of drug-eluting technologies in the management of in-stent restenosis.

MRI for peripheral artery disease: Introductory physics for vascular physicians.

Magnetic resonance imaging (MRI) has advanced significantly in the past decade and provides a safe and non-invasive method of evaluating peripheral artery disease (PAD), with and without using exogenous contrast agents. MRI offers a promising alternative for imaging patients but the complexity of MRI can make it less accessible for physicians to understand or use. This article provides a brief introduction to the technical principles of MRI for physicians who manage PAD patients. We discuss the basic principles of how MRI works and tailor the discussion to how MRI can evaluate anatomic characteristics of peripheral arterial lesions.

Magnetic resonance imaging characteristics of lesions relate to the difficulty of peripheral arterial endovascular procedures.

OBJECTIVE: Limitations with current peripheral arterial imaging modalities make selection of patients for percutaneous vascular interventions difficult. The purpose of this study was to determine whether a novel preprocedural magnetic resonance imaging (MRI) method can identify lesions that would be more challenging to cross during percutaneous vascular intervention. METHODS: Fourteen patients with peripheral arterial disease underwent MRI before their intervention. A novel steady-state free precession flow-independent magnetic resonance (MR) angiogram was used to locate lesions, and an ultrashort echo time image was used to characterize hard lesion components including calcium and dense collagen. Lesions were characterized as hard if ≥50% of the lumen was occluded with calcium or collagen (as determined by MR image characteristics) in the hardest cross section within the lesion. The primary outcome was the time it took to cross a guidewire through the target lesion. The secondary outcome was the need for stenting. RESULTS: Of 14 lesions, 8 (57%) were defined as hard and 6 (43%) were soft on the basis of MR image characteristics. Hard lesions took significantly longer to cross than soft lesions (average, 14 minutes 49 seconds vs 2 minutes 17 seconds; P = .003). Hard lesions also required stenting more often than soft lesions (Fisher exact test, P = .008). Of 14 lesions, 2 (14%) could not be crossed with a guidewire, and both lesions were hard. MR images also detected occult patencies and noncalcified hard lesions that could not be seen on X-ray angiography. CONCLUSIONS: MRI can be used to determine which peripheral arterial lesions are more difficult to cross with a guidewire. Future work will determine whether MRI lesion characterization can predict long-term endovascular outcomes to aid in procedure planning.

Public health campaigns and their effect on stroke knowledge in a high-risk urban population: A five-year study.

Background The level of knowledge of stroke risk factors and stroke symptoms within a population may determine their ability to recognize and ultimately react to a stroke. Independent agencies have addressed this through extensive awareness campaigns. The aim of this study was to determine the change in baseline knowledge of stroke risk factors, symptoms, and source of stroke knowledge in a high-risk Toronto population between 2010 and 2015. Methods Questionnaires were distributed to adults presenting to cardiovascular clinics at the University of Toronto in Toronto, Canada. In 2010 and 2015, a total of 207 and 818 individuals, respectively, participated in the study. Participants were identified as stroke literate if they identified (1) at least one stroke risk factor and (2) at least one stroke symptom. Results A total of 198 (95.6%) and 791 (96.7%) participants, respectively, completed the questionnaire in 2010 and 2015. The most frequently identified risk factors for stroke in 2010 and 2015 were, respectively, smoking (58.1%) and hypertension (49.0%). The most common stroke symptom identified was trouble speaking (56.6%) in 2010 and weakness, numbness or paralysis (67.1%) in 2015. Approximately equal percentages of respondents were able to identify ≥1 risk factor (80.3% vs. 83.1%, p = 0.34) and ≥1 symptom (90.9% vs. 88.7%, p = 0.38). Overall, the proportion of respondents who were able to correctly list ≥1 stroke risk factors and stroke symptoms was similar in both groups.(76.8% vs. 75.5%, p = 0.70). The most commonly reported stroke information resource was television (61.1% vs. 67.6%, p = 0.09). Conclusion Stroke literacy has remained stable in this selected high-risk population despite large investments in public campaigns over recent years. However, the baseline remains high over the study period. Evaluation of previous campaigns and development of targeted advertisements using more commonly used media sources offer opportunities to enhance education.

Smart(phone) Learning Experience Among Vascular Trainees Using a Response System Application.

OBJECTIVES: Smartphones have become the most important personal technological device. M-learning is learning through mobile device educational technology. We aim to assess the acceptability of a smartphone learning experience among the vascular trainees and determine if results could inform formal teaching efforts. METHODS: A survey of the vascular trainees at a single center was conducted following a trial of smartphone learning experience. A vascular fellow used a smartphone response system application (Polltogo, Inspirapps Inc.) to send a daily multiple-choice question to the vascular residents for 20 consecutive working days. The application allows for only one attempt from each user, and the answers are registered anonymously. However, each participant receives instant feedback on his/her response by viewing the correct answer after answering each question along with a distribution of answers among other users. RESULTS: A total of 9 trainees participated in the trial, and all of them filled a posttrial survey. All the trainees possessed smartphones. The majority (78%) were not aware of the concept of m-learning. The mobile engagement score (number of answers received divided by total possible answers) was 145/180 (81%). All the trainees were "satisfied" or "very satisfied" with the experience, and the same number stated that they were "likely" or "very likely" to use this technology in the future. The majority (89%) agreed that such an application could assist them in preparing for their board examination. On 3 occasions, 75% or more of the participating trainees answered the multiple-choice question incorrectly, which resulted in addressing the relevant topics in the unit's weekly teaching conference. CONCLUSION: Using smartphones for education is acceptable among the vascular trainees, and the trial of a response system application with instant written feedback represents a novel method for using smartphones for collaborative learning. Such an application can also inform program directors and surgical trainers of their trainees' learning needs.

Puncturing Plaques.

PURPOSE: To test and validate magnetic resonance imaging (MRI) sequences for peripheral artery lesion characterization and relate the MRI characteristics to the amount of force required for a guidewire to puncture peripheral chronic total occlusions (CTOs) as a surrogate for immediate failure of endovascular therapy. METHODS: Diseased superficial femoral, popliteal, and tibial artery segments containing 55 atherosclerotic lesions were excised from the amputated limbs of 7 patients with critical limb ischemia. The lesions were imaged at high resolution (75 µm3 voxels) with T2-weighted (T2W) and ultrashort echo time (UTE) sequences on a 7-T MR scanner. The MR images (n=15) were validated with micro-computed tomography and histology. CTOs (n=40) were classified by their MR signal characteristics as "soft" (signals indicating fat, thrombus, microchannels, or loose fibrous tissue), "hard" (collagen and/or speckled calcium signals), or "calcified" (calcified nodule signals). A 2-kg load cell advanced the back end of a 0.035-inch stiff guidewire at a fixed displacement rate (0.05 mm/s) through the CTOs, and the forces required to cross each lesion were measured. RESULTS: T2W images showed fat as hyperintense and hardened tissue as hypointense. Calcium and thrombus appeared as a signal void in conventional MRI sequences but were easily identified in UTE images (thrombus was hyperintense and calcium hypointense). MRI accurately differentiated "hard," "soft," and "calcified" CTOs based on associated guidewire puncture force. The guidewire could not enter "calcified" CTOs (n=6) at all. "Hard" CTOs (n=9) required a significantly higher (p<0.001) puncture force of 1.71±0.51 N vs 0.43±0.36 N for "soft" CTOs (n=25). CONCLUSION: MRI characteristics of PAD lesions correlate with guidewire puncture forces, an important aspect of crossability. Future work will determine if clinical MR scanners can be used to predict success in peripheral vascular interventions.

Critical Evaluation of Delayed Healing of Venous Leg Ulcers: A Retrospective Analysis in Canadian Patients.

BACKGROUND: Venous leg ulcers (VLUs) are common but challenging health problems. Better understanding of the risk factors involved in delayed healing of VLUs may therefore guide individualized treatment plans to improve patient outcomes. OBJECTIVE: We sought to identify the risk factors associated with delayed healing of VLUs in patients seen at a tertiary academic wound care clinic. METHODS: A retrospective analysis of 554 patients who presented to the Toronto Regional Wound Healing Clinic for VLUs in a 3-year period was performed. Patient and ulcer characteristics were recorded. Multivariate analyses were performed to compare patients with ulcer resolution and those whose ulcers did not resolve after 12-month follow-up. RESULTS: The average age of the patients was 67.3 ± 0.7 years, with 56 % being female. The most common comorbidities were hypertension (54 %), dyslipidemia (33 %), a history of smoking (30 %), and diabetes (26 %). Ulcer resolution was associated with a smaller ulcer size (odds ratio [OR] 0.984 [95 % confidence interval (CI) 0.973, 0.996]), shorter ulcer duration (OR 0.704 [95 % CI 0.574, 0.865]), and dyslipidemia (OR 1.848 [95 % CI 1.052, 3.246]). CONCLUSION: Pro-healing factors associated with VLUs were a smaller ulcer size and a shorter ulcer duration. Dyslipidemia was also associated with improved healing, potentially owing to the use of statins. Patients presenting with poorer-prognosis VLUs should receive more aggressive treatment with earlier referral to vascular surgery.