Fatty Infiltration of the Myocardium and Arrhythmogenesis: Potential Cellular and Molecular Mechanisms

Figures

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  Figure 1. (A) Schematic of myocardial fat depots in the myocardial wall of the right ventricle (Modified from Wong et al., 2016). (B) Epicardial fat tissue distribution in the ovine heart. (B) Normal adult sheep heart showing atrial and ventricular epicardial fat deposits. LAA, left atrial appendage; LV, left ventricle; EF, epicardial fat, on atrial and ventricular surfaces. Yellow box in (B1) is 2 × 3 cm. (B2), [Inset of box from (B1)] Oval and circles represent regions of dense atrial epicardial fat. (B3), LAA tissue section. Note significant epicardial fat layer with extensive adipocyte infiltration of the atrial muscle (Scale bar; 1mm). (B4), Tissue section of a region near yellow inset in (B3), showing myocytes (MYCTS), isles of adipocytes, and collagen (CLG; Picoserius staining). Scale bar: 50 μm. (Modified from O'Connell et al., 2015).

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  Figure 2. Analyses of Impulse conduction in normal weight and in obese ovine (Measurements during sinus rhythm and isochrones from left anterior oblique view). (A) Representative 5 ms isochronal maps. Note crowding of isochrones (i.e., slower propagation time) in the obese ovine, compared to the control. (B) Mean values of conduction velocity measured in the specified regions of the left atrium. Note that conduction velocity was reduced uniformly in all regions of the atrial myocardium. ANT, anterior; LA, left atrium; INF_LA, inferior left atrium; LAT_LA, lateral left atrium; POS_LA, posterior left atrium; ROO_LA, left atrial roof; SEP_LA, septal left atrium. Modified from Mahajan et al. (2015).

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  Figure 3. Disease associated myocardial fibro-fatty infiltrations (Fatty infiltrations, black asterisks; fibrosis, black or white crosses). (A) Atrial fibrillation (modified from Haemers et al., 2015). (B) Myotonic Dystrophy (magnification, 100X) (modified from Christensen et al., 2008). (C) Myocardial infarction (modified from Pouliopoulos et al., 2013). (D) Arrhythmogenic right ventricular cardiomyopathy (magnification, 200X). (Modified from Deshpande et al., 2016).

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  Figure 4. Schematic of mechanisms underlying increased arrhythmogenic risk with increased excess adiposity. ANS, autonomic nervous system; IL, interleukin; MMP, matrix metalloproteinase; ROS, reactive oxygen species; TLR, toll-like receptor; TNF, tumor necrosis factor. (Modified from Pandit et al., 2016).