To examine the link between bone material properties and skeletal fragility, we analyzed the mechanical, histological, biochemical, and spectroscopic properties of bones from a murine model of skeletal fragility (SAMP6). Intact bones from SAMP6 mice are weak and brittle compared with SAMR1 controls, a defect attributed to reduced strength of the bone matrix. The matrix weakness is attributed primarily to poorer organization of collagen fibers and reduced collagen content. Introduction:The contribution of age-related changes in tissue material properties to skeletal fragility is poorly understood. We previously reported that bones from SAMP6 mice are weak and brittle versus agematched controls. Our present objectives were to use the SAMP6 mouse to assess bone material properties in a model of skeletal fragility and to relate defects in the mechanical properties of bone to the properties of demineralized bone and to the structure and organization of collagen and mineral. Materials and Methods: Femora from 4-and 12-month-old SAMR1 (control) and SAMP6 mice were analyzed using bending and torsional mechanical testing of intact bones, tensile testing of demineralized bone, quantitative histology (including collagen fiber orientation), collagen cross-links biochemistry, and Raman spectroscopic analysis of mineral and collagen. Results: Intact bones from SAMP6 mice have normal elastic properties but inferior failure properties, with 60% lower fracture energy versus SAMR1 controls. The strength defect in SAMP6 bones was associated with a 23% reduction in demineralized bone strength, which in turn was associated with poorer collagen fiber organization, lower collagen content, and higher hydroxylysine levels. However, SAMP6 have normal levels of collagen cross-links and normal apatite mineral structure. Conclusions: Bones from SAMP6 osteoporotic mice are weak and brittle because of a defect in the strength of the bone matrix. This defect is attributed primarily to poorer organization of collagen fibers and reduced collagen content. These findings highlight the role of the collagen component of the bone matrix in influencing skeletal fragility.

Objective The objective of this study was to describe characteristics and early outcomes across a large multicenter cohort undergoing coarctation or hypoplastic aortic arch repair. Methods Patients undergoing coarctation or hypoplastic aortic arch repair (2006–2010) as their first cardiovascular operation in the Society of Thoracic Surgeons Congenital Heart Surgery Database were included. Group 1 patients consisted of those with coarctation or hypoplastic aortic arch without ventricular septal defect (coarctation or hypoplastic aortic arch, isolated); group 2, coarctation or hypoplastic aortic arch with ventricular septal defect (coarctation or hypoplastic aortic arch, ventricular septal defect); and group 3, coarctation or hypoplastic aortic arch with other major cardiac diagnoses (coarctation or hypoplastic aortic arch, other). Results The cohort included 5025 patients (95 centers): group 1, 2705 (54%); group 2, 840 (17%); and group 3, 1480 (29%). Group 1 underwent coarctation or hypoplastic aortic arch repair at an older age than groups 2 and 3 (groups 1, 2, and 3, 75%, 99%, and 88% < 1 year old, respectively; P<.0001). The most common operative techniques for coarctation or hypoplastic aortic arch repair (group 1) were end-to-end (33%) or extended end-to-end (56%) anastomosis. Overall mortality was 2.4%, and was 1%, 2.5%, and 4.8% for groups 1, 2, and 3 respectively (P < .0001). Ventricular septal defect management strategies for group 2 patients included ventricular septal defect closure (n = 211, 25%), pulmonary artery band (n = 89, 11%), or no intervention (n = 540, 64%) without significant difference in mortality (4%, 1%, 2%; P = .15). Postoperative complications occurred in 36% of patients overall and were more common in groups 2 and 3. There were no occurrences of spinal cord injury (0/973). Conclusions In the current era, primary coarctation or hypoplastic aortic arch repair is performed predominantly in neonates and infants. Overall mortality is low, although those with concomitant defects are at risk for higher morbidity and mortality. The risk of spinal cord injury is lower than previously reported.

A 4-year-old asymptomatic girl presented for elective transcatheter closure of her ostium secundum atrial septal defect (ASD). Her examination revealed a fixed split second heart sound with a 2/6 systolic ejection murmur at the left upper sternal border and a right ventricular lift. Transthoracic echocardiogram demonstrated a 15-mm secundum ASD with a mildly dilated right ventricle. The left coronary artery (LCA) could not be readily identified on the study. The patient was referred for percutaneous device closure when a preprocedural transesophageal echocardiogram revealed a moderatesized secundum ASD with left to right shunting, moderate right ventricle dilation, and an anomalous origin of the LCA from the right sinus of Valsalva was identified ( Figure 1A). The origin and distribution of the right coronary artery was normal. Cardiac catheterization revealed a Qp:Qs ratio of 2:1. Aortography confirmed the anomalous origin of the LCA from the right sinus of Valsalva with a course posterior to the aorta ( Figure 2A).With balloon sizing using the stop flow technique, the ASD measured 12 mm in diameter. A 12-mm Amplatzer septal occluder was then positioned but not released in the defect and was evaluated by transesophageal echocardiogram. The Amplatzer septal occluder was well seated but concern arose secondary to the device's proximity to the anomalous LCA as it coursed posterior and adjacent to the atrial septum ( Figure 1B). A repeat aortography revealed systolic compression of the LCA ( Figure 2B and online-only Data Supplement Video). No electrocardiogram abnormalities suggesting ischemia or hemodynamic changes occurred. The device was successfully removed and a repeat aortogram demonstrated no further distortion of the LCA ( Figure 2C). The patient recovered well and has been recommended for surgical ASD closure.In the current era, there exist very few contraindications to transcatheter closure of secundum ASDs 1 and very few periand postprocedural complications.2 Known device-related complications of percutaneous ASD closure, particularly with the Amplatzer septal occluder, include worsening of aortic regurgitation and cardiac erosion.3 Additionally, little information is available regarding the presence of coronary artery anomalies in patients undergoing ASD device closure. To our knowledge, this is the first reported case providing