(a) Heterotopic femoral heart transplantation. (b) Schemes of blood circulation of transplanted hearts and representative photographs of the posttransplants. Reduced flow through the LV in the unloaded LV model with intact aortic valve (upper row) versus increased pressure and volume load in the distended LV model with AR creation (lower row). (c) Postoperative trans-femoral echocardiography. Representative images from a distended LV with AR. (d) A grading system for the amount of EFE. EFE scores (Grade 0, no EFE; Grade 1, islets of EFE; Grade 2, thin EFE tissue covering a half circumference of the endocardium; Grade 3, thin EFE tissue (less than 100 μm) covering a full circumference of the endocardium; Grade 4, thick EFE tissue (more than 100 μm) covering a full circumference of the endocardium). White scale bar, 200 μm.