Utility of longitudinal and radial myocardial velocities assessed by color tissue Doppler imaging in dogs with dilated cardiomyopathy

INTRODUCTION/OBJECTIVES Dilated cardiomyopathy (DCM) is characterized by left ventricular (LV) dilatation and impaired myocardial systolic function. Tissue Doppler imaging (TDI) has been developed to assess myocardial wall velocities and might therefore be expected to be a useful tool in the diagnosis of DCM. The aim of the study was to ascertain whether TDI variables differ between DCM dogs and normal control dogs. ANIMALS, MATERIALS AND METHODS Eighty-three client-owned dogs, 37 with DCM and 46 control dogs, were included in the study. A prospective observational study was conducted. RESULTS There were no significant differences in systolic wave velocities in radial or longitudinal motion in either the lateral or the medial LV wall in dogs with DCM compared to control dogs. Medial longitudinal and radial myocardial velocities in early diastole were significantly increased in DCM dogs compared to control dogs. Left ventricular systolic time-to-peak interval was significantly prolonged in dogs with DCM compared to control dogs in both longitudinal lateral (P=0.0002) and medial (P=0.005), as well as radial (P=0.0006), myocardial wall motion. STUDY LIMITATIONS Median body weight and heart rate were significantly higher in DCM dogs than in normal dogs. Reliable TDI data could not be obtained in all myocardial segments in all dogs. CONCLUSIONS Our study shows that delay in the onset of the myocardial systolic wave, assessed as time-to-peak interval, is a consistent finding in dogs with DCM compared to normal dogs but decreased systolic wave velocity is not.