Objectives To determine whether cardiac magnetic resonance (CMR) in vivo T1-mapping can measure myocardial area at risk (AAR) compared with microspheres or T2-mapping CMR. Background If T2-weighted CMR is abnormal in the AAR due to edema related to myocardial ischemia, then T1-weighted CMR should also be able to detect and accurately quantify AAR. Methods Dogs (n=9) underwent a 2 hour coronary occlusion followed by 4 hours of reperfusion. CMR of the left ventricle was performed for mapping of T1 and T2 prior to any contrast administration. AAR was defined as regions which had a T1 or T2 value (ms) greater than 2SD from remote, and regions with microsphere blood flow (ml/min/g) during occlusion less than 2SD from remote. Infarct size was determined by triphenyltetrazolium chloride staining. Results The relaxation parameters T1 and T2 were increased in the AAR compared to remote myocardium (T1: 1133±55 vs. 915±33ms, T2: 71±6 vs. 49±3 ms; mean±SD). On a slice-by-slice basis (n=78 slices), AAR by T1- and T2-mapping correlated (R2=0.95, p<0.001) with good agreement (0.4±16.6 % of slice, mean±2SD). On a whole-heart analysis, T1 measurements of left ventricular mass, AAR and myocardial salvage correlated to microsphere measures (R2=0.94) with good agreement (−1.4±11.2 g of myocardium; mean±2SD). Corresponding T2 measurements of left ventricular mass, AAR, and salvage correlated to microsphere analysis (R2=0.96, agreement 1.6±9.2 g of myocardium; mean±2SD). Median infarct size was 30% of the AAR (range 12–52). Conclusions For determining area at risk after acute myocardial infarction, non-contrast T1-mapping and T2-mapping sequences yield similar quantitative results, and both agree well with microspheres. The relaxation properties T1 and T2 both change in a way that is consistent with the presence of myocardial edema following myocardial ischemia/reperfusion.

Aims The aims of this study were to evaluate the incidence of postoperatively restricted weight-bearing and its association with outcome in patients who undergo surgery for a fracture of the hip. Patients and Methods Patient aged > 60 years undergoing surgery for a hip fracture were identified in the 2016 National Surgical Quality Improvement Program (NSQIP) Hip Fracture Targeted Procedure Dataset. Analysis of the effect of restricted weight-bearing on adverse events, delirium, infection, transfusion, length of stay, return to the operating theatre, readmission and mortality within 30 days postoperatively were assessed. Multivariate regression analysis was used to adjust for confounding demographic, comorbid and procedural characteristics. Results Of the 4918 patients who met inclusion criteria, 3668 (63.53%) were allowed to weight-bear as tolerated postoperatively. Controlling for patient and procedural factors, multivariate odds of any adverse event, major adverse event, delirium, infection, transfusion, length of stay ≥ 75th percentile (six days) and mortality within 30 days were all higher in patients with weight-bearing restrictions. Notably, there were no differences for thromboembolic events, return to the operating theatre or readmission within 30 days between the groups. Conclusion Elderly patients with a fracture of the hip with postoperative weight-bearing restrictions have a significantly greater risk of developing most adverse events compared with those who are encouraged to weight-bear as tolerated. These findings emphasize the importance of immediate weight-bearing as tolerated to optimize the outcome in these frail patients; however nearly 25% of surgeons fail to meet this evidence-based guideline. Cite this article: Bone Joint J 2018;100-B:1377–84.

The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell.

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