Assessment of left ventricular regional function in affected and carrier dogs with duchenne muscular dystrophy using speckle tracking echocardiography

BACKGROUND Two-dimensional speckle tracking echocardiography (STE) is a relatively new method to detect regional myocardial dysfunction. To assess left ventricular (LV) regional myocardial dysfunction using STE in Duchenne muscular dystrophy model dogs (CXMD(J)) without overt clinical signs of heart failure. METHODS Six affected dogs, 8 carrier dogs with CXMD(J), and 8 control dogs were used. Conventional echocardiography, systolic and diastolic function by Doppler echocardiography, tissue Doppler imaging (TDI), and strain indices using STE, were assessed and compared among the 3 groups. RESULTS Significant differences were seen in body weight, transmitral E wave and E' wave derived from TDI among the 3 groups. Although no significant difference was observed in any global strain indices, in segmental analysis, the peak radial strain rate during early diastole in posterior segment at chordae the tendineae level showed significant differences among the 3 groups. CONCLUSIONS The myocardial strain rate by STE served to detect the impaired cardiac diastolic function in CXMD(J) without any obvious LV dilation or clinical signs. The radial strain rate may be a useful parameter to detect early myocardial impairment in CXMD(J).