Phrenic nerve reconstruction by intercostal nerve neurotization on pigs

Background: Our aim was to investigate the motor outcome, effects on the diaphragm muscle, and delimit the regained nerve conduction capacity of the transected phrenic nerve, following its reconstruction to prepare the subjects to electrophrenic respiration. Methods: All one-year-old 12 healthy pigs (German Landrace) weighing 45 to 50 kg were used in the study. Three groups, each of which consisted of four subjects were composed; control group, anastomosis group, and anastomosis plus pericardial flap group. Initial nerve conduction studies were applied and data were recorded. All the subjects encountered left phrenic nerve transection and except the control group, distal stumps were immediately repaired with intercostal nerve neurotization and coaptation. One subject from each group was sacrificed at 1 h, 2 h, 6 h and 4 weeks after surgery, following final nerve conduction assessments for comparison. Results and conclusions: Harvested nerve distal stumps and diaphragm muscles were examined for histopathological changes. The results yielded that reconstructed nerves responded to stimulation in the end of four weeks and diaphragm was excitable thereafter. Wrapping the repair site with pericardial fat tissue did not prove to be superior to nerve repair alone. More detailed experimental studies are needed to find out the best estimates of timing for repair and neurostimulation.