Impact of cardiovascular risk factors on severity of peripheral artery disease

OBJECTIVE The development of peripheral artery disease is affected by the presence of cardiovascular risk factors. It is unclear, whether particular risk factors are leading to different clinical stages of peripheral artery disease. The aim of this retrospective cross-sectional study was to assess the association of cardiovascular risk factors with the presence of critical limb ischaemia. METHODS The study cohort was derived from a consecutive registry of patients undergoing endovascular therapy in a tertiary referral centre between January 2000 and April 2014. Patients undergoing first-time endovascular intervention for chronic peripheral artery disease of the lower extremities were included. Univariate and multivariate logistic regression models were used to assess the association of age, sex, diabetes mellitus, hypertension, dyslipidaemia, smoking, and renal insufficiency with critical limb ischaemia vs. intermittent claudication. RESULTS A total of 3406 patients were included in the study (mean age 71.7 ± 11.8 years, 2075 [61%] male). There was a significant association of age (OR 1.67, 95%-CI 1.53-1.82, p < 0.001), male gender (OR 1.23, 95%-CI 1.04-1.47, p = 0.016), diabetes (OR 1.99, 95%-CI 1.68-2.36, p < 0.001) and renal insufficiency (OR 1.62, 95%-CI 1.35-1.96, p < 0.001) with the likelihood of critical limb ischaemia. Smoking was associated with intermittent claudication rather than critical limb ischaemia (OR 0.78, 95%-CI 0.65-0.94, p = 0.010), while hypertension and dyslipidaemia did not show an association with critical limb ischaemia. CONCLUSIONS In peripheral artery disease patients undergoing first-time endovascular treatment, age, male gender, diabetes, and renal insufficiency were the strongest predictors for the presence of critical limb ischaemia.

Dynamic changes of intramural hematoma in patients with acute spontaneous internal carotid artery dissection.

BACKGROUND We prospectively investigated temporal and spatial evolution of intramural hematomas in patients with acute spontaneous internal carotid artery dissection using repeated magnetic resonance imaging over six-months. AIM The aim of the present study was to assess dynamic changes of intramural hematoma in patients with acute spontaneous internal carotid artery dissection at multiple follow-up time-points with T1w, PD/T2w, and magnetic resonance angiography. METHODS We performed serial multiparametric magnetic resonance imaging in 10 patients with spontaneous internal carotid artery dissection on admission, at days 1, 3, 7-14 and at months 1·5, 3, and 6. We calculated the volume and extension of the hyperintense intramural hematoma using T1w and PD/T2w fat suppressed sequences and assessed the degree of stenosis due to the hematoma using magnetic resonance angiography. RESULTS Mean interval from symptom onset to first magnetic resonance imaging was two-days (SD 2·7). Two patients presented with ischemic stroke, three with transient ischemic attacks, and five with pain and local symptoms only. Nine patients had a transient increase of the intramural hematoma volume, mainly up to day 10 after symptom onset. Fifty percent had a transient increase in the degree of the internal carotid artery stenosis on MRA, one resulting in a temporary occlusion. Lesions older than one-week were predominantly characterized by a shift from iso- to hyperintese signal on T2w images. At three-month follow-up, intramural hematoma was no longer detectable in 80% of patients and had completely resolved in all patients after six-months. CONCLUSIONS Spatial and temporal dynamics of intramural hematomas after spontaneous internal carotid artery dissection showed an early volume increase with concomitant progression of the internal carotid artery stenosis in 5 of 10 patients. Although spontaneous internal carotid artery dissection overall carries a good prognosis with spontaneous hematoma resorption in all our patients, early follow-up imaging may be considered, especially in case of new clinical symptoms.

Time window for recanalization in basilar artery occlusion: Speculative synthesis.

Basilar artery occlusion (BAO) is one of the most devastating forms of stroke and few patients have good outcomes without recanalization. Most centers apply recanalization therapies for BAO up to 12-24 hours after symptom onset, which is a substantially longer time window than the 4.5 hours used in anterior circulation stroke. In this speculative synthesis, we discuss recent advances in BAO treatment in order to understand why and under which circumstances longer symptom duration might not necrotize the brainstem and turn therapeutic attempts futile. We raise the possibility that distinct features of the posterior circulation, e.g., highly developed, persistent collateral arterial network, reverse filling of the distal basilar artery, and delicate plasma flow siding the clot, might sustain brittle patency of brainstem perforators in the face of stepwise growth of the thrombus. Meanwhile, the tissue clock characterizing the rapid necrosis of a typical anterior circulation penumbra will not start. During this perilous time period, recanalization at any point would salvage the brainstem from eventual necrosis caused by imminent reinforcement and further building up of the clot.

Occlusion Location of Middle Cerebral Artery Stroke and Outcome after Endovascular Treatment.

BACKGROUND The aim of this study was to analyze the influence of the location of middle cerebral artery (MCA) occlusion on recanalization, complications and outcome after endovascular therapy. METHODS Four-hundred sixty-four patients with acute MCA occlusions were treated with endovascular therapy. RESULTS Two-hundred ninety-three patients had M1 occlusions, 116 had M2, and 55 had M3/4 occlusions. Partial or complete recanalization was more frequently achieved in M1 (76.8%) than in M2 (59.1%) or M3/4 (47.3%, p < 0.001) occlusions, but favorable outcome (modified Rankin Scale 0-2) was less frequent in M1 (50.9%) than M2 (63.7%) or M3/4 (72.7%, p = 0.018) occlusions. Symptomatic intracerebral hemorrhage (ICH) did not differ between occlusion sites, but asymptomatic ICH was more common in M1 (22.6%) than in M2 occlusions (8.6%, p = 0.003). Recanalization was associated with favorable outcome in M1 (p < 0.001) and proximal M2 (p = 0.003) but not in distal M2 or M3/4 occlusions. CONCLUSIONS Recanalization with endovascular therapy was more frequently achieved in patients with proximal than distal MCA occlusions, but recanalization was associated with favorable outcome only in M1 and proximal M2 occlusions. Outcome was better with distal than proximal occlusions. This study shows that recanalization can be used as a surrogate marker for clinical outcome only in patients with proximal occlusions.

Investigation of hemodynamics in an in vitro system simulating left ventricular support through the right subclavian artery using 4-dimensional flow magnetic resonance imaging.

OBJECTIVES Left ventricular assist devices are an important treatment option for patients with heart failure alter the hemodynamics in the heart and great vessels. Because in vivo magnetic resonance studies of patients with ventricular assist devices are not possible, in vitro models represent an important tool to investigate flow alterations caused by these systems. By using an in vitro magnetic resonance-compatible model that mimics physiologic conditions as close as possible, this work investigated the flow characteristics using 4-dimensional flow-sensitive magnetic resonance imaging of a left ventricular assist device with outflow via the right subclavian artery as commonly used in cardiothoracic surgery in the recent past. METHODS An in vitro model was developed consisting of an aorta with its supra-aortic branches connected to a left ventricular assist device simulating the pulsatile flow of the native failing heart. A second left ventricular assist device supplied the aorta with continuous flow via the right subclavian artery. Four-dimensional flow-sensitive magnetic resonance imaging was performed for different flow rates of the left ventricular assist device simulating the native heart and the left ventricular assist device providing the continuous flow. Flow characteristics were qualitatively and quantitatively evaluated in the entire vessel system. RESULTS Flow characteristics inside the aorta and its upper branching vessels revealed that the right subclavian artery and the right carotid artery were solely supported by the continuous-flow left ventricular assist device for all flow rates. The flow rates in the brain-supplying arteries are only marginally affected by different operating conditions. The qualitative analysis revealed only minor effects on the flow characteristics, such as weakly pronounced vortex flow caused by the retrograde flow via the brachiocephalic artery. CONCLUSIONS The results indicate that, despite the massive alterations in natural hemodynamics due to the retrograde flow via the right subclavian and brachiocephalic arteries, there are no drastic consequences on the flow in the brain-feeding arteries and the flow characteristics in the ascending and descending aortas. It may be beneficial to adjust the operating condition of the left ventricular assist device to the residual function of the failing heart.

Proximal Femoral Osteotomies with the Paediatric Hip Plate (LCP): Valgus osteotomy.

OBJECTIVE Proximal femoral osteotomy with stable fixation and sufficient correction. Low complication rates due to exact preoperative planning. INDICATIONS Congenital or traumatic femoral neck pseudarthrosis. Coxa vara. CONTRAINDICATIONS None. In severe deformities, a single femoral osteotomy may not solve the problem; thus, additional correction, e.g., a pelvic osteotomy, is required. SURGICAL TECHNIQUE Correct planning of the correction angle. Lateral approach. Subperiosteal detachment of vastus lateralis muscle. Place guide wire on the femoral neck to judge anteversion. Insert positioning wire 5 mm distal to trochanteric physis. Insert 2.8 mm Kirschner wire in the femoral neck. Osteotomy of the femur after marking the rotation by Kirschner wires or oscillating saw. Slide LC plate over Kirschner wires. Replace Kirschner wires with screws. Reduction of the femoral shaft to the plate with bone forceps. Definitive fixation of the plate to the femoral shaft by cortex or locking screws. Readaptation of vastus lateralis muscle over the plate. POSTOPERATIVE MANAGEMENT Partial weightbearing for 4-6 weeks depending on the age of the patient without any external fixation (e. g. cast) is possible. RESULTS Recent studies support the authors' findings of sufficient correction and stable fixation after proximal femoral osteotomy with the LCP pediatric hip plate. Low complication rates and stable fixation.

Comparison of Mixed and Kinematic Uniform Boundary Conditions in Homogenized Elasticity of Femoral Trabecular Bone Using Microfinite Element Analyses

Mechanical properties of human trabecular bone play an important role in age-related bone fragility and implant stability. Micro-finite element (microFE) analysis allows computing the apparent elastic properties of trabecular bone biopsies, but the results depend on the type of applied boundary conditions (BCs). In this study, 167 femoral trabecular cubic biopsies with a side length of 5.3 mm were analyzed using microFE analysis to compare their stiffness systematically with kinematic uniform boundary conditions (KUBCs) and periodicity-compatible mixed uniform boundary conditions (PMUBCs). The obtained elastic constants were then used in the volume fraction and fabric-based orthotropic Zysset-Curnier model to identify their respective model parameters. As expected, PMUBCs lead to more compliant apparent elastic properties than KUBCs, especially in shear. The differences in stiffness decreased with bone volume fraction and mean intercept length. Unlike KUBCs, PMUBCs were sensitive to heterogeneity of the biopsies. The Zysset-Curnier model predicted apparent elastic constants successfully in both cases with adjusted coefficients of determination of 0.986 for KUBCs and 0.975 for PMUBCs. The role of these boundary conditions in finite element analyses of whole bones and bone-implant systems will need to be investigated in future work.

Effect of boundary conditions on yield properties of human femoral trabecular bone

Trabecular bone plays an important mechanical role in bone fractures and implant stability. Homogenized nonlinear finite element (FE) analysis of whole bones can deliver improved fracture risk and implant loosening assessment. Such simulations require the knowledge of mechanical properties such as an appropriate yield behavior and criterion for trabecular bone. Identification of a complete yield surface is extremely difficult experimentally but can be achieved in silico by using micro-FE analysis on cubical trabecular volume elements. Nevertheless, the influence of the boundary conditions (BCs), which are applied to such volume elements, on the obtained yield properties remains unknown. Therefore, this study compared homogenized yield properties along 17 load cases of 126 human femoral trabecular cubic specimens computed with classical kinematic uniform BCs (KUBCs) and a new set of mixed uniform BCs, namely periodicity-compatible mixed uniform BCs (PMUBCs). In stress space, PMUBCs lead to 7–72 % lower yield stresses compared to KUBCs. The yield surfaces obtained with both KUBCs and PMUBCs demonstrate a pressure-sensitive ellipsoidal shape. A volume fraction and fabric-based quadric yield function successfully fitted the yield surfaces of both BCs with a correlation coefficient R2≥0.93. As expected, yield strains show only a weak dependency on bone volume fraction and fabric. The role of the two BCs in homogenized FE analysis of whole bones will need to be investigated and validated with experimental results at the whole bone level in future studies.

Nitinol Stent Oversizing in Patients Undergoing Popliteal Artery Revascularization: A Finite Element Study

Nitinol stent oversizing is frequently performed in peripheral arteries to ensure a desirable lumen gain. However, the clinical effect of mis-sizing remains controversial. The goal of this study was to provide a better understanding of the structural and hemodynamic effects of Nitinol stent oversizing. Five patient-specific numerical models of non-calcified popliteal arteries were developed to simulate the deployment of Nitinol stents with oversizing ratios ranging from 1.1 to 1.8. In addition to arterial biomechanics, computational fluid dynamics methods were adopted to simulate the physiological blood flow inside the stented arteries. Results showed that stent oversizing led to a limited increase in the acute lumen gain, albeit at the cost of a significant increase in arterial wall stresses. Furthermore, localized areas affected by low Wall Shear Stress increased with higher oversizing ratios. Stents were also negatively impacted by the procedure as their fatigue safety factors gradually decreased with oversizing. These adverse effects to both the artery walls and stents may create circumstances for restenosis. Although the ideal oversizing ratio is stent-specific, this study showed that Nitinol stent oversizing has a very small impact on the immediate lumen gain, which contradicts the clinical motivations of the procedure.

Fast Prediction of Femoral Biomechanics Using Supervised Machine Learning and Statistical Shape Modeling

Finite element (FE) analysis is an important computational tool in biomechanics. However, its adoption into clinical practice has been hampered by its computational complexity and required high technical competences for clinicians. In this paper we propose a supervised learning approach to predict the outcome of the FE analysis. We demonstrate our approach on clinical CT and X-ray femur images for FE predictions ( FEP), with features extracted, respectively, from a statistical shape model and from 2D-based morphometric and density information. Using leave-one-out experiments and sensitivity analysis, comprising a database of 89 clinical cases, our method is capable of predicting the distribution of stress values for a walking loading condition with an average correlation coefficient of 0.984 and 0.976, for CT and X-ray images, respectively. These findings suggest that supervised learning approaches have the potential to leverage the clinical integration of mechanical simulations for the treatment of musculoskeletal conditions.

Relative femoral neck lengthening improves pain and hip function in proximal femoral deformities with a high-riding trochanter

BACKGROUND Complex proximal femoral deformities, including an elevated greater trochanter, short femoral neck, and aspherical head-neck junction, often result in pain and impaired hip function resulting from intra-/extraarticular impingement. Relative femoral neck lengthening may address these deformities, but mid-term results of this approach have not been widely reported. QUESTIONS/PURPOSES Do patients who have undergone relative femoral neck lengthening show (1) less hip pain and greater function; (2) improved radiographic parameters; (3) significant complications requiring subsequent surgery; and (4) progression of osteoarthrosis (OA) or conversion to total hip arthroplasty (THA) at mid-term followup? METHODS We retrospectively reviewed 40 patients (41 hips) with isolated relative femoral neck lengthening between 1998 and 2006 with sequelae of Legg-Calvé-Perthes disease (38 hips [93%]), slipped capital femoral epiphysis (two hips [5%]), and postseptic arthritis (one hip [2%]). During this time, the general indications for this procedure included a high-riding greater trochanter with a short femoral neck with abductor weakness and symptomatic intra-/extraarticular impingement. Mean patient followup was 8 years (range, 5-13 years), and complete followup was available in 38 patients (39 hips [95%]). We evaluated pain and function with the impingement test, limp, abductor force, Merle d'Aubigné-Postel score, and range of motion. Radiographic parameters included trochanteric height, alpha angle, and progression of OA. Subsequent surgeries, complications, and conversion to THA were summarized. RESULTS The proportion of positive anterior impingement tests decreased from 93% (38 of 41 hips) preoperatively to 49% (17 of 35 hips) at latest followup (p = 0.002); the proportion of limp decreased from 76% (31 of 41 hips) to 9% (three of 35 hips; p < 0.001); the proportion of normal abductor strength increased from 17% (seven of 41 hips) to 91% (32 of 35 hips; p < 0.001); mean Merle d'Aubigné-Postel score increased from 14 ± 1.7 (range, 9-17) to 17 ± 1.5 (range, 13-18; p < 0.001); mean internal rotation increased to 25° ± 15° (range, 0°-60°; p = 0.045), external rotation to 32° ± 14° (range, 5°-70°; p = 0.013), and abduction to 37° ± 13° (range, 10°-50°; p = 0.004). Eighty percent of hips (33 of 41 hips) showed normal trochanteric height; alpha angle improved to 42° ± 10° (range, 27°-90°). Two hips (5%) had subsequent surgeries as a result of lack of containment; four of 41 hips (10%) had complications resulting in reoperation. Fourteen of 35 hips (40%) showed progression of OA; four of 40 hips (10%) converted to THA. CONCLUSIONS Relative femoral neck lengthening in hips with combined intra- and extraarticular impingement results in reduced pain, improved function, and improved radiographic parameters of the proximal femur. Although lack of long-term complications is gratifying, progression of OA was not prevented and remains an area for future research.

Twelve percent of hips with a primary cam deformity exhibit a slip-like morphology resembling sequelae of slipped capital femoral epiphysis

BACKGROUND In some hips with cam-type femoroacetabular impingement (FAI), we observed a morphology resembling a more subtle form of slipped capital femoral epiphysis (SCFE). Theoretically, the morphology in these hips should differ from hips with a primary cam-type deformity. QUESTIONS/PURPOSES We asked if (1) head-neck offset; (2) epiphyseal angle; and (3) tilt angle differ among hips with a slip-like morphology, idiopathic cam, hips after in situ pinning of SCFE, and normal hips; and (4) what is the prevalence of a slip-like morphology among cam-type hips? METHODS We retrospectively compared the three-dimensional anatomy of hips with a slip-like morphology (29 hips), in situ pinning for SCFE (eight hips), idiopathic cam deformity (171 hips), and 30 normal hips using radial MRI arthrography. Normal hips were derived from 17 asymptomatic volunteers. All other hips were recruited from a series of 277 hips (243 patients) seen at a specialized academic hip center between 2006 and 2010. Forty-one hips with isolated pincer deformity were excluded. Thirty-six of 236 hips had a known cause of cam impingement (secondary cam), including eight hips after in situ pinning of SCFE (postslip group). The 200 hips with a primary cam were separated in hips with a slip-like morphology (combination of positive fovea sign [if the neck axis did not intersect with the fovea capitis] and a tilt angle [between the neck axis and perpendicular to the basis of the epiphysis] exceeding 4°) and hips with an idiopathic cam. We evaluated offset ratio, epiphyseal angle (angle between the neck axis and line connecting the center of the femoral head and the point where the physis meets the articular surface), and tilt angle circumferentially around the femoral head-neck axis. Prevalence of slip-like morphology was determined based on the total of 236 hips with cam deformities. RESULTS Offset ratio was decreased anterosuperiorly in idiopathic cam, slip-like, and postslip (eg, 1 o'clock position with a mean offset ranging from 0.00 to 0.14; p < 0.001 for all groups) compared with normal hips (0.25 ± 0.06 [95% confidence interval, 0.13-0.37]) and increased posteroinferiorly in slip-like (eg, 8 o'clock position, 0.5 ± 0.09 [0.32-0.68]; p < 0.001) and postslip groups (0.55 ± 0.12 [0.32-0.78]; p < 0.001) and did not differ in idiopathic cam (0.32 ± 0.09 [0.15-0.49]; p = 0.323) compared with normal (0.31 ± 0.07 [0.18-0.44]) groups. Epiphyseal angle was increased anterosuperiorly in the slip-like (eg, 1 o'clock position, 70° ± 9° [51°-88°]; p < 0.001) and postslip groups (75° ± 13° [49°-100°]; p = 0.008) and decreased in idiopathic cam (50° ± 8° [35°-65°]; p < 0.001) compared with normal hips (58° ± 8° [43°-74°]). Posteroinferiorly, epiphyseal angle was decreased in slip-like (eg, 8 o'clock position, 54° ± 10° [34°-74°]; p < 0.001) and postslip (44° ± 11° [23°-65°]; p < 0.001) groups and did not differ in idiopathic cam (76° ± 8° [61°-91°]; p = 0.099) compared with normal (73° ± 7° [59°-88°]) groups. Tilt angle increased in slip-like (eg, 2/8 o'clock position, 14° ± 8° [-1° to 30°]; p < 0.001) and postslip hips (29° ± 10° [9°-48°]; p < 0.001) and decreased in hips with idiopathic cam (-7° ± 5° [-17° to 4°]; p < 0.001) compared with normal (-1° ± 5° [-10° to 8°]) hips. The prevalence of a slip-like morphology was 12%. CONCLUSIONS The slip-like morphology is the second most frequent pathomorphology in hips with primary cam deformity. MRI arthrography of the hip allows identifying a slip-like morphology, which resembles hips after in situ pinning of SCFE and distinctly differs from hips with idiopathic cam. These results support previous studies reporting that SCFE might be a risk factor for cam-type FAI.

Comparative Effectiveness and Safety of New-Generation Versus Early-Generation Drug-Eluting Stents According to Complexity of Coronary Artery Disease: A Patient-Level Pooled Analysis of 6,081 Patients.

OBJECTIVES The purpose of this study was to compare the 2-year safety and effectiveness of new- versus early-generation drug-eluting stents (DES) according to the severity of coronary artery disease (CAD) as assessed by the SYNTAX (Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) score. BACKGROUND New-generation DES are considered the standard-of-care in patients with CAD undergoing percutaneous coronary intervention. However, there are few data investigating the effects of new- over early-generation DES according to the anatomic complexity of CAD. METHODS Patient-level data from 4 contemporary, all-comers trials were pooled. The primary device-oriented clinical endpoint was the composite of cardiac death, myocardial infarction, or ischemia-driven target-lesion revascularization (TLR). The principal effectiveness and safety endpoints were TLR and definite stent thrombosis (ST), respectively. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated at 2 years for overall comparisons, as well as stratified for patients with lower (SYNTAX score ≤11) and higher complexity (SYNTAX score >11). RESULTS A total of 6,081 patients were included in the study. New-generation DES (n = 4,554) compared with early-generation DES (n = 1,527) reduced the primary endpoint (HR: 0.75 [95% CI: 0.63 to 0.89]; p = 0.001) without interaction (p = 0.219) between patients with lower (HR: 0.86 [95% CI: 0.64 to 1.16]; p = 0.322) versus higher CAD complexity (HR: 0.68 [95% CI: 0.54 to 0.85]; p = 0.001). In patients with SYNTAX score >11, new-generation DES significantly reduced TLR (HR: 0.36 [95% CI: 0.26 to 0.51]; p < 0.001) and definite ST (HR: 0.28 [95% CI: 0.15 to 0.55]; p < 0.001) to a greater extent than in the low-complexity group (TLR pint = 0.059; ST pint = 0.013). New-generation DES decreased the risk of cardiac mortality in patients with SYNTAX score >11 (HR: 0.45 [95% CI: 0.27 to 0.76]; p = 0.003) but not in patients with SYNTAX score ≤11 (pint = 0.042). CONCLUSIONS New-generation DES improve clinical outcomes compared with early-generation DES, with a greater safety and effectiveness in patients with SYNTAX score >11.