Development and Application of a Large Animal Model for Blood Flow Studies in Univentricular Circulation

All articles of this category (opens in new window) Background: Pulmonary artery (PA) blood flow in univentricular circulation is critical for its outcome. An impaired diaphragmatic movement may influence PA blood flow. In a porcine model, we tested the effect of diaphragmatic palsy on PA blood flow. In addition, we investigated the impact of unilateral diaphragmatic pacing on PA blood flow. Currently, no reproducible large animal models of univentricular circulation for PA blood flow testing are available. Methods: We used 20 pigs to develop and apply an animal model for cavopulmonary connection, studying the effect of diaphragmatic palsy on PA blood flow. Initially, we created a stable model for univentricular circulation in 14 pigs. Thereafter, we studied the effect of right-sided unilateral diaphragmatic palsy and subsequent right-sided diaphragmatic pacing in animals with univentricular circulation ( n = 6) on PA blood flow using transit time flow measurements. Results: In eight pigs, we established a unidirectional cavopulmonary connection (UDCPC), and in six pigs, a bidirectional cavopulmonary connection (BDCPC) was created. The BDCPC resulted in an impaired cardiopulmonary state (cardiac output dropped (3.15 ± 0.21 to 2.17 ± 0.19 L/minute; p < 0.01), mean arterial pressure plummeted (80.8 ± 3.7 to 49.3 ± 7.3 mm Hg; p = 0.02), arterial lactate concentration rose (0.82 ± 0.09 to 4.36 ± 0.96 mmol/L; p = 0.01), arterial oxygen saturation dropped (95.8 ± 1.1 to 60.9 ± 10.4 %; p < 0.01) and right ventricular function deteriorated (tricuspid annular plane systolic excursion 12 ± 0.7 to 5 ± 0.7 mm; p < 0.01)). In contrast, in the UDCPC group, the cardiopulmonary parameters indicated a stable condition. Transection of the right phrenic nerve resulted in a reduced diaphragmatic excursion (dropped from 0.65 ± 0.13 to 0.09 ± 0.04 cm, p < 0.05) and mean blood flow in the superior cavopulmonary connection flow (decreased from 0.66 ± 0.13 to 0.54 ± 0.13 L/minute, p < 0.05). After right-sided diaphragmatic pacing, both parameters increased significantly.: diaphragm excursion rose to 1.99 ± 0.46 cm ( p < 0.05), while mean flow increased to 0.58 ± 0.12 L/minute. No significant changes in blood gas analyses and hemodynamics were observed, indicating a stable state. Conclusion: A unidirectional cavopulmonary connection is a more suitable acute model in pigs for a univentricular circulation. Diaphragmatic excursion is restored by pacing the phrenic nerve. Pacing the injured phrenic nerve results in improved ipsilateral pulmonary artery blood flow. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany