Echocardiographic evaluation of the LV structure and function in mice with and without the first open-chest surgery. (A and B) Representative 2-D guided M-mode images of the left ventricle in a mouse without surgery (A) and the age-matched animal with surgery (B) during diastole (d) and systole (s). In B, echocardiographic evaluation was performed 2 d after surgery. IVS, interventricular septum; LVID, LV internal dimension; LVPW, LV posterior wall.