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We consider the theoretical and empirical implications of the structural basis of panethnicity and of the layering of ethnic boundaries in residential patterns while simultaneously evaluating the ‘panethnic hypothesis’, that is, the extent to which homogeneity within panethnic categories can be assumed. Our results do show a panethnic effect – greater residential proximity is evident within panethnic boundaries than between, net of ethnic group size and metropolitan area, but this association clearly depends on immigration. While findings generally show a lower degree of social distance between panethnic subgroups, particularly for blacks, whites and Latinos and less for Asians, ethno-national groups continue to maintain some degree of distinctiveness within a racialized context.

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Structured Abstract Objectives We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy. Background Catheter-based annuloplasty for secondary mitral regurgitation exploits the proximity of the coronary sinus to the mitral annulus, but is limited by anatomic variants and coronary artery entrapment. Methods The procedure, “cerclage annuloplasty,” is guided by MRI roadmaps fused with live X-ray. A coronary sinus guidewire traverses a short segment of basal septal myocardium to reenter the right heart where it is exchanged for a suture. Tension is applied interactively during imaging and secured with a locking device. Results We found two feasible suture pathways from the great cardiac vein across the interventricular septum to create cerclage. Right-ventricular septal reentry required shorter fluoroscopy times than right atrial reentry, which entailed a longer intramyocardial traversal but did not cross the tricuspid valve. Graded tension progressively reduced septal-lateral annular diameter but not end-systolic elastance or regional myocardial function. A simple arch-like device protected entrapped coronary arteries from compression even during supra-therapeutic tension. Cerclage reduced mitral regurgitation fraction (from 22.8 ± 12.7% to 7.2 ± 4.4%, p=0.04) by slice-tracking velocity-encoded MRI. Flexible cerclage reduced annular size but preserved annular motion. Cerclage also displaced the posterior annulus towards the papillary muscles. Cerclage introduced reciprocal constraint to the left ventricular outflow tract and mitral annulus that enhanced leaflet coaptation. A sample of human coronary venograms and CT angiograms suggested that most have suitable venous anatomy for cerclage. Conclusions Transcatheter mitral cerclage annuloplasty acutely reduces mitral regurgitation in porcine ischemic cardiomyopathy. Entrapped coronary arteries can be protected. MRI provided insight into the mechanism of cerclage action.