[Experimental investigations of muscle transplants in correction of congenital diaphragmatic defects (author's transl)].

Rives muscle plasty using a pediculate flap of the latissimus dorsi muscle is an approved method for correction of large congenital diaphragmatic defects. To study morphology and function of the transplanted muscle flap 10 beagle dogs were operated upon bilaterally in two stages. Thus a total of 20 muscle transplants was evaluated. A standard Rives plasty was performed, emg electrodes were inserted into the diaphragm as well as into the muscle transplant. The surgical procedure was tolerated very well, there was no operative mortality. The period of observation varied between 18 and 48 weeks, the average being 30 weeks. Postoperatively there was no electric activity found in the muscle transplants, whereas the diaphragm showed its characteristic interference pattern during inspiration. In 5 cases, however, action potentials appeared in the muscle flap after 12 to 16 weeks. They had the semblance of fibrillation potentials and short sharp waves and were considered to be preceding reinnervation potentials, which occured 24 to 32 weeks postoperatively in these cases. In 2 cases the emg findings were inconstant, in the residual 13 cases there was no electrical activity in the muscle transplant during all the observation time. The emg findings corresponded to the histological postmortem findings. These showed in altogether 6 cases numerous intact muscle fibres as well as nerve trunks with neurites, especially in the neighbourhood of the diaphragm. In the middle of the flap and even more near the thoracic wall the number of intact muscle fibres decreased. Thus a partial reinnervation due to muscular neurotization starting from the diaphragmatic margin was assumed in these cases. In the rest of the flaps the muscles were largely atrophic and showed considerable lipomatosis, only minor fibrosis and never a distinct scar formation. Therefore, the flaps represented living tissue with intact vascularization and functionally good adaptability. Reinnervation, observed in some cases, is not the main factor for the good clinical results obtained with Rives muscle plasty, but can improve adaptability and elasticity of the transplant considerably. According to the lack of scar formation and the preponderance of fatty tissue an increase of the transplant considerably. According to the lack of scar formation and the preponderance of fatty tissue an increase of the transplants size during growth seems possible. Thus Rives muscle plasty using a flap of the latissimus dorsi muscle to cover large congenital diaphragmatic defects seems morphologically as well as functionally superior to other procedures especially those using plastic material.