Dyskinesis in Chagasic myocardium: centerline analysis of wall motion using cardiac-gated magnetic resonance images of mice

Abstract

We report on the use of centerline analysis of cardiac-gated magnetic resonance images to measure wall motion abnormalities in mice infected with Trypanosoma cruzi. To our knowledge, this is the first report of segmental wall motion abnormalities in an animal model of Chagas' disease. Chagas' disease patients with severe cardiac involvement exhibit mild hypokinesis in an extensive region of the left ventricle and dyskinesis in the apical region. We observed dyskinetic segments in a similar region of the hearts of infected wild-type mice. Dyskinesis was not observed in infected mice lacking macrophage inflammatory protein-1alpha, a chemokine that may play an important role in the cardiac remodeling that is normally observed in mouse models of Chagas' disease and in human patients. This study aimed to demonstrate the utility of cardiac-gated magnetic resonance imaging and centerline analysis as a straightforward method for monitoring regional left ventricular wall motion in transgenic and/or diseased mice.

Fig. 1

Schematic diagram showing the distribution of chords along the walls of the left ventricle of the heart.

Fig. 2

Representative short-axis diastolic spin-echo MR images of mice. A: uninfected MIP-1α null; B: infected MIP-1α null; C: uninfected C57BL/6×129sv; D: infected C57BL/6×129sv.

Fig. 3

Representative long-axis systolic and diastolic MR images of mice. Representative long-axis spin-echo images of the hearts of mice (A and B: uninfected C57BL/6×129sv; C and D: infected C57BL/6×129sv; E and F: uninfected MIP-1α null; G and H: infected MIP-1α null) at end diastole (panels on left) and end systole (panels on right) as used for centerline analysis.

Fig. 4

Plot of wall motion versus chord number for one representative mouse from each group. For clarity of presentation, results from one mouse from each group are shown for Chords 25−75, which encompass the apical and diaphragmatic regions.

Fig. 5

Normalized wall motion by region. Bar graph (mean±S.E.M.) of normalized wall motion by heart region for the four groups of mice showing the dyskinesis in the infected wild-type mice in the apical–diaphragmatic region.