Right ventricular phenotypic characteristics in subjects with primary pulmonary hypertension or idiopathic dilated cardiomyopathy

Background: Studies of animal models and human subjects with cardiomyopathi es suggest that cardiac myocyte and ventricular chamber remodeling show dis tinct phenotypic characteristics that may be dependent on specific signalin g pathways. Methods and Results: In this study, we characterize right ventricular (RV) chamber size, end-diastolic thickness, myocardial mass, and ejection fracti on (EF) in human subjects with chronic heart failure from primary pulmonary hypertension (PPH; n = 10) and idiopathic dilated cardiomyopathy (IDC; n = to). subjects underwent gated cardiac magnetic resonance imaging (MRI), an d the RVs were phenotypically classified based on the presence or absence o f hypertrophy (increased mass), systolic dysfunction (reduced EE); and degr ee of wall thickness (concentric v eccentric pattern of hypertrophy). Withi n this schema, five abnormal phenotypes could be identified. In PPH subject s, in whom the RV is subjected to the uniform insult of chronic pressure ov erload, four different abnormal phenotypes: were identified. Conclusions: These data indicate that distinct structural/functional ventri cular chamber phenotypes may be classified by MRT, and that a uniform insul t can result in multiple RV phenotypes.