Tissue Doppler imaging for the pre-clinical diagnosis of cardiomyopathy.

Duchenne muscular dystrophy is an important cause of cardiomyopathy in children and adolescents and is caused by mutations in the gene coding for the protein dystrophin [1]. Dystrophin participates in linking the sarcomere to the sarcolemma and extracellular matrix and plays a role in cell signalling [2]. The disease is characterised by skeletal and cardiac myopathies. Because it is inherited as an X-linked recessive disorder, males are the primarily affected gender, although female carriers can present with cardiac abnormalities later in life. Given the devastating and relentless progression once the disease is well established, early and accurate diagnosis of cardiac dysfunction is an important goal. Animal models have proved useful in increasing our understanding of this and other cardiomyopathies. In this issue of the Journal, Chetboul et al. [3], using a natural canine model of the human disease: the golden retriever muscular dystrophy (GRMD) dog model, report on the application of tissue Doppler imaging (TDI) in the early diagnosis of cardiac dysfunction. In the GRMD dog model, fibrosis in the subepicardial region of the left ventricular free wall and myofibrillar loss are classic histopathological findings. Subsequently, the pathology extends to other segments including the septum and papillary muscles. Chetboul et al. [3] imaged the animals and acquired M-mode TD data from the posterior wall in short axis views. Despite similar heart rate and blood pressure, TD systolic and diastolic endocardial velocities and