Heat map visualization for electrocardiogram data analysis.

BACKGROUND: Most electrocardiogram (ECG) studies still take advantage of traditional statistical functions, and the results are mostly presented in tables, histograms, and curves. Few papers display ECG data by visual means. The aim of this study was to analyze and show data for electrocardiographic left ventricular hypertrophy (LVH) with ST-segment elevation (STE) by a heat map in order to explore the feasibility and clinical value of heat mapping for ECG data visualization. METHODS: We sequentially collected the electrocardiograms of inpatients in the First Affiliated Hospital of Shantou University Medical College from July 2015 to December 2015 in order to screen cases of LVH with STE. HemI 1.0 software was used to draw heat maps to display the STE of each lead of each collected ECG. Cluster analysis was carried out based on the heat map and the results were drawn as tree maps (pedigree maps) in the heat map. RESULTS: In total, 60 cases of electrocardiographic LVH with STE were screened and analyzed. STE leads were mainly in the V1, V2 and V3 leads. The ST-segment shifts of each lead of each collected ECG could be conveniently visualized in the heat map. According to cluster analysis in the heat map, STE leads were clustered into two categories, comprising of the right precordial leads (V1, V2, V3) and others (V4, V5, V6, I, II, III, aVF, aVL, aVR). Moreover, the STE amplitude in 40% (24 out of 60) of cases reached the threshold specified in the STEMI guideline. These cases also could be fully displayed and visualized in the heat map. Cluster analysis in the heat map showed that the III, aVF and aVR leads could be clustered together, the V1, V2, V3 and V4 leads could be clustered together, and the V5, V6, I and aVL leads could be clustered together. CONCLUSION: Heat maps and cluster analysis can be used to fully display every lead of each electrocardiogram and provide relatively comprehensive information.

[Impact of fenofibrate on NO and endothelial VCAM-1 expression in hyperlipidemic rats].

OBJECTIVE: To investigate the mechanism of hyperlipidemia- and imflammation-induced functional impairment of the endothelium. METHODS: The experiment was conducted using 3 groups of rats fed for 20 weeks with standard chow (control group), high-fat diet and high-fat diet with daily fenofibrate treatment (10 mg/kg, starting since the fifth week), respectively. After 4 and 20 weeks of feeding, respectively, serum lipid level and NO concentration were measured in the rats, and the epithelial vascular cell adhesion molecule-1 (VCAM-1) expression and cell adhesiveness to the aortic endothelium were observed. RESULTS: Compared with the control group, the rats with hyperlipidemia induced by long-term high-fat diet feeding showed lower NO concentration and increased leukocyte accumulation on the endothelial surface, exhibiting also stronger and more extensive endothelial expression of VCAM-1. In contrast, the hyperlipidemic rats with fenofibrate treatment shoed significantly decreased VCAM-1 expression and leukocyte adhesion with recovery of the NO level. CONCLUSION: NO deficiency and activation of inflammation are involved in vascular impairment in rats with high-fat diet-induced hyperlipidemia, and fenofibrate can effectively prevent atherosclerosis by restoring NO concentration and down-regulating VCAM-1 expression in these rats.

Effect of hyperlipidemia on endothelial VCAM-1 expression and the protective role of fenofibrate.

The effect of hyperlipidemia and inflammation on endothelial functions was studied. The enrolled included control (basic chow), hyperlipidemia and fenofibrate-treated groups (high fat diet). The hyperlipidemia model was set up by four-week atherogenic diet, followed by a 16-week treatment in the fenofibrate-treated group (fenofibrate 40 mg/kg every day) and without treatment in the hyperlipidemia group, respectively. In the 20th week, serum lipid level and NO levels were measured, and the expression of vascular cell adhesion molecule-1 (VCAM-1) and cell adhesiveness in aortic endothelia observed by computer-aided system. Compared with the control group, hyperlipidemia rats showed lower levels of NO and increases in leukocyte accumulation on the endothelial surface, also stronger and more extensive endothelial expression of VCAM-1. In fenofibrate-treated group, the expression of VCAM-1 and leukocyte accumulation on the endothelial surface was decreased, while serum levels of NO were increased as compared with hyperlipidemia group. Hyperlipidemia can inhibit the NO activity and promote the damage of VACA-1 to aortic endothelia. Fenofibrate can effectively prevent the pathogenesis of atherosclerosis by restoring NO levels and down-regulating the VCAM-1 expression.