1.
The pharmaceutical management of cardiac allograft vasculopathy after heart transplantation.
Spitaleri, G, Farrero Torres, M, Sabatino, M, Potena, L
Expert opinion on pharmacotherapy. 2020;(11):1367-1376
Abstract
INTRODUCTION Cardiac allograft vasculopathy (CAV) is a major limitation to long-term survival after heart transplantation. Its peculiar pathophysiology involves multifactorial pathways including immune-mediated and metabolic risk factors, which are associated with the development of specific pathological lesions. The often diffuse and chronic nature of the disease reduces the effectiveness of revascularization procedures, and pharmacological prevention of the disease is the sole therapeutic approach with some proven efficacy. AREAS COVERED In this article, after briefly outlining the risk factors for CAV, the authors revise the potential pharmacological approaches that may reduce the burden of CAV. While several therapies have shown convincing efficacy in termsĀ of CAV prevention diagnosed by coronary imaging, very few have been reported to improve prognosis with any meaningful level of evidence. EXPERT OPINION The authors believe that a customizable approach is necessary for clinical practice given the currently available evidence. Furthermore, it is important, in the future, to address the glaring therapeutic gap of an effective treatment against donor-specific antibodies, whose effect on endothelial injury is currently one of the major mechanisms of CAV development and for which no pharmacological treatment is currently available.
2.
Automatic detection of regional heart rejection in USPIO-enhanced MRI.
Chang, HH, Moura, JM, Wu, YL, Ho, C
IEEE transactions on medical imaging. 2008;(8):1095-106
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Abstract
Contrast-enhanced magnetic resonance imaging (MRI) is useful to study the infiltration of cells in vivo. This research adopts ultrasmall superparamagnetic iron oxide (USPIO) particles as contrast agents. USPIO particles administered intravenously can be endocytosed by circulating immune cells, in particular, macrophages. Hence, macrophages are labeled with USPIO particles. When a transplanted heart undergoes rejection, immune cells will infiltrate the allograft. Imaged by T(2)(*)-weighted MRI, USPIO-labeled macrophages display dark pixel intensities. Detecting these labeled cells in the image facilitates the identification of acute heart rejection. This paper develops a classifier to detect the presence of USPIO-labeled macrophages in the myocardium in the framework of spectral graph theory. First, we describe a USPIO-enhanced heart image with a graph. Classification becomes equivalent to partitioning the graph into two disjoint subgraphs. We use the Cheeger constant of the graph as an objective functional to derive the classifier. We represent the classifier as a linear combination of basis functions given from the spectral analysis of the graph Laplacian. Minimization of the Cheeger constant based functional leads to the optimal classifier. Experimental results and comparisons with other methods suggest the feasibility of our approach to study the rejection of hearts imaged by USPIO-enhanced MRI.