Hearts from infant r a t s were grafted t o the abdominal c a v i t i e s of infant o r adult hosts by end-to-side anastomosis of the g r a f t ' s aorta t o the h o s t dorsal a o r t a , and of t h e donor's pulmonary a r t e r y t o the i n f e r i o r vena cava of the host. transplants, circulation through the heart bypassed the l e f t atrium and ventricle. t o normal adult s i z e s and t h e i r r i g h t ventricles had hypertrophied commensurate with the l e f t side.