Andrew D. Dueck

Association between chronic cerebrospinal venous insufficiency and multiple sclerosis: a meta-analysis

Background: It has been proposed by Zamboni and colleagues that multiple sclerosis is caused by chronic cerebrospinal venous insufficiency, a term used to describe ultrasound-detectable abnormalities in the anatomy and flow of intra- and extracerebral veins. We conducted a meta-analysis of studies that reported the frequency of chronic cerebrospinal venous insufficiency among patients with and those without multiple sclerosis. Methods: We searched MEDLINE and EMBASE as well as bibliographies of relevant articles for eligible studies. We included studies if they used ultrasound to diagnose chronic cerebrospinal venous insufficiency and compared the frequency of the venous abnormalities among patients with and those without multiple sclerosis. Results: We identified eight eligible studies: all included healthy controls, and four of them also included a control group of patients with neurologic diseases other than multiple sclerosis. Chronic cerebrospinal venous insufficiency was more frequent among patients with multiple sclerosis than among the healthy controls (odds ratio [OR] 13.5, 95% confidence interval [CI] 2.6–71.4), but there was extensive unexplained heterogeneity among the studies. The association remained significant in the most conservative sensitivity analysis (OR 3.7, 95% CI 1.2–11.0), in which we removed the initial study by Zamboni and colleagues and added a study that did not find chronic cerebrospinal venous insufficiency in any patient. Although chronic cerebrospinal venous insufficiency was also more frequent among patients with multiple sclerosis than among controls with other neurologic diseases (OR 32.5, 95% CI 0.6–1775.7), the association was not statistically significant, the 95% CI was wide, and the OR was less extreme after removal of the study by Zamboni and colleagues (OR 3.5, 95% 0.8–15.8). Interpretation: Our findings showed a positive association between chronic cerebrospinal venous insufficiency and multiple sclerosis. However, poor reporting of the success of blinding and marked heterogeneity among the studies included in our review precluded definitive conclusions.

Associated injuries, management, and outcomes of blunt abdominal aortic injury

OBJECTIVE Blunt abdominal aortic injury (BAAI) is very rare, and current literature is limited to case series of single-center experience. Through an analysis of the National Trauma Data Bank, the largest aggregation of United States trauma registry data, our aim was to characterize the associated injury pattern, contemporary management, and in-hospital outcomes of patients with BAAI. METHODS We used a nested case-control design. The overall cohort consisted of adult patients (age ≥ 16 years) severely injured (Injury Severity Score ≥ 16) after blunt trauma who were treated at a level 1 or 2 trauma center in years 2007 to 2009. Cases were patients with BAAI and were frequency-matched by age group and mechanism to randomly selected controls at a one-to-five ratio. Multivariable matched analysis (conditional logistic regression) was used to derive adjusted measures of association between BAAI and adjacent arterial, intra-abdominal, and bony injuries. RESULTS We identified 436 patients with BAAI from 180 centers. The mean Injury Severity Score was 35 ± 14, and most patients were injured in motor vehicle crashes (84%). Multivariable analysis showed injury to the thoracic aorta, renal and iliac artery, small bowel, colon, liver, pancreas, and kidney, as well as lumbar spine fractures were independently associated with BAAI. A total of 394 patients (90%) were managed nonoperatively, and 42 (10%) underwent repair. Of these 42 patients, 29 (69%) underwent endovascular repair, with 11 patients undergoing open aortic repair and two extra-anatomic bypasses. Median time from admission to repair was 1 day (interquartile range, 1-2 days). Overall mortality was 29%. A total of 271 (69%) patients managed nonoperatively survived to hospital discharge. CONCLUSIONS The index of suspicion for BAAI should be raised in severely injured patients by the presence of injuries to the lumbar spine, bowel, retroperitoneal organs, and adjacent major arteries. Although endovascular repair is the most common intervention, most patients are managed nonoperatively and survive to hospital discharge.

v) The Management of Vascular Injuries in Extremity Trauma

Abstract Unrecognised vascular injuries following extremity trauma can result in disastrous outcomes ranging from limb dysfunction to amputation. All extremity trauma should be approached with a high index of suspicion for vascular injuries. Clinical examination is the mainstay of diagnosis. The role of Colour Flow Doppler scanning is expanding. In the operating room, patients should be heparinised, damaged arterial segments should be debrided and primary end-to-end anastomosis is the preferred method of repair. Compartment syndrome and thrombosis are major postoperative complications that demand prompt diagnosis and treatment.

Puncturing Plaques: Relating MRI Characteristics of Peripheral Artery Lesions to Guidewire Puncture Forces

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.

Peripheral Endovascular Interventions in the Era of Precision Medicine: Tying Wire, Drug, and Device Selection to Plaque Morphology.

An “endovascular-first” strategy has been widely adopted in the treatment of symptomatic occlusive peripheral artery disease (PAD). This shift in clinical practice is largely attributed to growing revascularization technologies, improved training in endovascular skills across specialties, and advancements in vascular imaging. There is no highlevel evidence to guide decision making with respect to which patients are appropriate candidates for percutaneous vascular interventions (PVIs) and which treatments are best suited for a particular patient or lesion type. The “endovascular-first” strategy has recently come into question based on growing evidence linking PVI failure to worse outcomes with secondary bypass grafting, highlighting the importance of patient selection. Clinicians hoped that the recently published, long-awaited update to the TransAtlantic Inter-Society Consensus–II (TASC-II) guidelines would provide direction on optimal treatment strategies. Unfortunately, this consensus document no longer makes treatment recommendations due to a paucity of evidence. The current evidence is primarily based on observational studies without adequate long-term follow-up. Even the relevance of the BASIL trial, the only multicenter randomized controlled trial (RCT) to compare bypass surgery to PVI, is questioned. The PVI group in this study received only balloon angioplasty, which no longer reflects modern endovascular treatment strategies. There are inherent limitations to the utility of long, expensive RCTs when the treatment arms no longer reflect rapidly evolving clinical practice. Without formal guidelines, physicians currently must resort to a combination of “trial-and-error” and a “use what’s in stock” approach to patient, wire, and device selection. This has been implicated in poor outcomes, including high technical failure and reintervention rates. In this article, we speculate on how plaque pathophysiology and morphology might facilitate an objective, tailored approach to wire, drug, and device selection. Yahagi et al recently updated their modified American Heart Association classification scheme for atherosclerotic lesions. Using this classification scheme, we take a mechanistic approach to discussing adjunctive wire, drug, and device selection considerations for specific plaque morphologies.

Burning Bridges: Mechanisms and Implications of Endovascular Failure in the Treatment of Peripheral Artery Disease.

An “endovascular-first” strategy for the treatment of peripheral artery disease (PAD) has been widely adopted. The low periprocedural risks make it an attractive option, and one of the cited reasons for the increasing popularity of this treatment strategy is the belief that if the endovascular treatment is unsuccessful, surgical treatment options are preserved at minimal risk to patients. Growing evidence calls the “endovascular-first” strategy into question because bypass after endovascular failure has been linked to worse outcomes. This was first demonstrated in the coronary literature, where coronary artery bypass patients had more adverse events, including earlier morbidity and mortality, if they had previous percutaneous interventions. More recently in the critical limb ischemia (CLI) literature, a by-treatment-received analysis of the BASIL trial (the only randomized control trial comparing peripheral angioplasty and open surgery) demonstrated that patients who had endovascular failure with subsequent bypass had significantly worse amputation free survival compared to patients with primary bypass. These findings have since been supported by other nonrandomized studies. It has been proposed that these results may be biased due to selection from a subset of the population that is at higher risk of adverse outcomes regardless of treatment strategy. This risk could be driven by either systemic factors, such as hypercoagulable states, or ipsilateral anatomy. In this regard, Nolan et al have demonstrated that only ipsilateral percutaneous interventions led to worse secondary bypass outcomes. If interventions were done on the contralateral leg, there were no significant differences compared with primary bypass, which suggests that systemic factors were not affecting subsequent bypass outcomes. While the degree of stenosis and length of lesion has been correlated with outcome, the impact of the composition of the lesion has not been well defined in the literature. Potential mechanisms by which previous endovascular treatment could affect future bypasses or increase major adverse limb events have not been defined. The purpose of this article is to propose potential mechanisms that contribute to endovascular failure and their implications for subsequent revascularization attempts and outcomes.

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.

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.

Fishing for BASS: Surveying Primary Physicians in the Barriers to Aortic Screening Study

Introduction In response to published guidelines for abdominal aortic aneurysm (AAA) screening, primary care physicians were surveyed to determine attitudes and identify barriers to screening. Methods Six hundred standardized, structured surveys were distributed to all primary care practitioners in a defined geographic area. Participation was voluntary, and results were anonymous. Results A total of 10.7% of surveys were returned. All questions were answered by >93% of respondents. A total of 71.9% of respondents were general practitioners; 94.4% worked in a community setting. 60.9% saw >11 male patients per week who were older than 65 years of age. Responses indicated support for identifying asymptomatic AAAs; only 4.7% thought their patients were too sick to undergo repair, 0% felt their patients would be unwilling to undergo repair, and 0% felt the risk of rupture was too small to justify repair. Access to vascular surgical services was available to more than 75% in the hospital closest to them, and to 100% in the city in which they practice. A total of 42.2% were aware of recommendations regarding AAA screening, and 65.6% of physicians routinely screened eligible patients for AAAs. Screening for other diseases was more frequent. Respondents routinely screened their patients for breast cancer (79.1%), prostate cancer (80.5%), colon cancer (80.9%), and hypertension (83.7%); 42.9% routinely screened for peripheral artery disease. Conclusion Screening for AAAs lags significantly behind other major screening programs. Although primary practitioners are routinely exposed to the target population, a minority of patients are screened. Neither access to a vascular surgeon nor knowledge about the importance of AAAs appears to be limiting factors. Despite recent publicity, almost 60% of primary care physicians remain unaware of screening guidelines for AAAs. Of those who were aware of guidelines, only one third follow them. Further research and education is required to increase the efficacy of screening.