Although rare, hypertrophic cardiomyopathy (HCM) with midventricular obstruction is often associated with severe symptoms and complications. None of the existing HCM animal models display this particular phenotype. Our group developed a mouse line that overexpresses the ErbB2 receptor (ErbB2tg) in cardiomyocytes; we previously showed that the ErbB2 receptor induces cardiomyocyte hypertrophy, myocyte disarray, and fibrosis compatible with HCM. In the current study, we sought to further echocardiographically characterize the ErbB2tg mouse line as a model of HCM. Compared with their wild-type littermates, ErbB2tg mice show increased left ventricular (LV) mass, concentric LV hypertrophy, and papillary muscle hypertrophy. This hypertrophy was accompanied by diastolic dysfunction, expressed as reduced E:A ratio, prolonged deceleration time, and elevated E:e′ ratio. In addition, ErbB2tg mice consistently showed midcavity obstruction with elevated LV gradients, and the flow profile revealed a prolonged pressure increase and a delayed peak, indicating dynamic obstruction. The ejection fraction was increased in ErbB2tg mice, due to reduced end-diastolic and end-systolic LV volumes. Furthermore, systolic radial strain and systolic radial strain rate but not systolic circumferential strain and longitudinal strain were decreased in ErbB2tg compared with wild-type mice. In conclusion, the phenotype of the ErbB2tg mouse model is consistent with midventricular HCM in many important aspects, including massive LV hypertrophy, diastolic dysfunction, and midcavity obstruction. This pattern is unique for a small animal model, suggesting that ErbB2tg mice may be well suited for research into the hemodynamics and treatment of this rare form of HCM.
|Number of pages||10|
|Publication status||Published - 1 Aug 2016|