Establishment and Magnetocardiographic Changes of Pressure Overload Left Ventricular Hypertrophy and Its Regression in Rats

ABSTRACT

BACKGROUND AND OBJECTIVES: Regression of left ventricular hypertrophy (LVH) is important because development of myocardial ischemia, heart failure or arrhythmias may be reduced. However, an animal model for LVH regression is not well established and there are no useful parameters to predict LVH regression. Magnetocardiogram (MCG), magnetic signal generated from the heart, has recently been investigated for the detection of electrical current changes of the heart. This study was undertaken to establish rat models of LVH-regression and to assess MCG changes during LVH induction and regression. MATERIALS AND METHODS: Rat models of pressure overload LVH were established by transverse aortic constriction (TAC) and LVH regression was generated by untying 2 weeks after TAC. Hemodynamic, echocardiographic and biochemical evaluation were performed in order to confirm this model. Magnetic fields were recorded with a SQUID gradiometer before and after TAC, and also recorded at 1, 3, 7, and 14 days after untying, respectively. RESULTS: Rat models of LVH-regression were established successfully by TAC and untying. The pressure gradient across TAC disappeared within 10 minutes after untying. LV weight, LV weight/body weight ratio, LV mass and expression level of atrial natriuretic factor were significantly increased following TAC and decreased to baseline value after pressure unloading. Deeper S waves and strain patterns were observed after LVH induction and gradually returned to basal levels over the 2 weeks after untying. CONCLUSION: MCG changes in the rat models of LVH-regression indicate that MCG can be a helpful modality for the diagnosis and evaluation of LVH as well as follow-up after treatment of LVH.