Prospective analysis of myocardial strain through the evolution of Chagas disease in the hamster animal model

Abstract

Speckle tracking echocardiography (STE) enables early diagnosis of myocardial damage by evaluating myocardial strain. We aimed to study sequential changes in structural and ventricular functional parameters during Chagas disease (CD) natural history in an animal model. 37 Syrian hamsters were inoculated intraperitoneally with Trypanosoma cruzi (Chagas) and 20 with saline (Control). Echocardiography was performed before the infection (baseline), at 1 month (acute phase), 4, 6, and 8 months (chronic phase) using Vevo 2100 (Fujifilm Inc.) ultrasound system. Left ventricular end-diastolic diameter, Left ventricular end-systolic diameter (LVESD), Left ventricular ejection fraction (LVEF), Global longitudinal (GLS), circumferential (GCS) and radial (GRS) strain were evaluated. Tricuspid annular plane systolic excursion (TAPSE) was used to assess right ventricular function. At 8 months, animals were euthanized and LV myocardial samples were analyzed for quantitation of inflammation and fibrosis. LVEF decreased over time in Chagas group and a difference from Control was detected at 6 months (p-value of groups#time interaction = 0.005). There was a pronounced decrease in GLS, GCS and TAPSE in Chagas group (p-value of groups#time interaction = 0.003 for GLS, < 0.001 for GCS and < 0.009 for TAPSE vs Control) since the first month. LVESD, LVEF and GLS were significantly correlated to the number of inflammatory cells (r = 0.41, p = 0.046; r = - 0.42, p = 0.042; r = 0.41, p = 0.047) but not to fibrosis. In the Syrian hamster model of CD STE parameters (GLS and GCS) showed an early decrease. Changes in LVEF, LVESD, and GLS were correlated to myocardial inflammation but not to fibrosis.

Keywords: Animal experimental model; Chagas cardiomyopathy; Echocardiography; Hamsters; Speckle-tracking; Strain.

Fig. 1

Myocardial strain analysis in hamsters from Parasternal long-axis view (PSLAX) and Parasternal short-axis view (PSSAX). LV strain was measured across a Region of interest (ROI) in the parasternal long-axis view (A) and short-axis view (B)

Fig. 2

Left ventricle end-systolic dimension (LVESD) and ejection fraction (LVEF) through time in Chagas and Control groups. Panel A Behavior of LVESD over time in Chagas and Control groups. Panel B LVEF over time in Chagas and Control groups. LVESD left ventricular end-systolic diameter, LVEF_2D two-dimensional derived left ventricular ejection fraction by the area-length method. Comparison between groups through time with mixed model ANOVA

Fig. 3

Deformation echocardiographic parameters evolution over time in Chagas and Control groups. Panel A Evolution of GLS over time in Chagas and Control groups. Panel B Evolution of GCS over time in Chagas and Control groups. GLS global longitudinal strain, GCS: global circumferential strain. Comparison between groups through time with mixed model ANOVA

Fig. 4

Evolution of TAPSE over time in Chagas and Control groups. TAPSE tricuspid annular plane systolic excursion. Comparison between groups through time with mixed model ANOVA

Fig. 5

Quantitative histological analysis of myocardial inflammation in Control group (A) and Chagas group (B). Graph representing the greater number of inflammatory cells in animals with Chagas disease compared to animals in the control group (C)

Fig. 6

Quantitative histological analysis of interstitial myocardial fibrosis in Control group (A) and Chagas group (B). Graphic representing the highest percentage of interstitial fibrosis in animals with Chagas disease compared to animals in the control group (C)