Kratz, TobiasTobiasKratzDauvergne, JanJanDauvergneRuff, RomanRomanRuffKoch, TimoTimoKochBreuer, JohannesJohannesBreuerAsfour, BoulosBoulosAsfourHerberg, UlrikeUlrikeHerbergBierbach, BenjaminBenjaminBierbach2024-05-132024-05-132024-04-05https://publica.fraunhofer.de/handle/publica/46776810.1186/s13019-024-02707-wBackground: A frequent complication of Fontan operations is unilateral diaphragmatic paresis, which leads to hemodynamic deterioration of the Fontan circulation. A potential new therapeutic option is the unilateral diaphragmatic pacemaker. In this study, we investigated the most effective stimulation location for a potential fully implantable system in a porcine model. Methods: Five pigs (20.8 ± 0.95 kg) underwent implantation of a customized cuff electrode placed around the right phrenic nerve. A bipolar myocardial pacing electrode was sutured adjacent to the motor point and peripherally at the costophrenic angle (peripheral diaphragmatic muscle). The electrodes were stimulated 30 times per minute with a pulse duration of 200 µs and a stimulation time of 300 ms. Current intensity was the only variable changed during the experiment. Results: Effective stimulation occurred at 0.26 ± 0.024 mA at the phrenic nerve and 7 ± 1.22 mA at the motor point, a significant difference in amperage (p = 0.005). Even with a maximum stimulation of 10 mA at the peripheral diaphragm muscle, however, no effective stimulation was observed. Conclusion: The phrenic nerve seems to be the best location for direct stimulation by a unilateral thoracic diaphragm pacemaker in terms of the required amperage level in a porcine model.enjournal article