The role of the left atrium in the development of pulmonary hypertension.

The experiments were performed on dogs to confirm the hypothesis that the left atrium plays an important role in raising the pulmonary arterial pressure through the autonomic nervous system. In Experiment I, the left auricular resection of dogs resulted in elevated pulmonary arterial pressure. In Experiment 2, 6% Dextran infusion was performed on four groups of dogs: (1) intact dogs (2) dogs with the left auricular resection (3) with the cardiac denervation (4) with both the left auricular resection and the cardiac denervation. The pulmonary arterial resistance increased after the infusion in the dogs with simple left auricular resection, but was relatively unchanged in all others. The result shows that cardiac denervation prevents the increase of the pulmonary arterial resistance due to the left auricular resection. From this we can conclude that the left auricular resection causes an increase in the pulmonary arterial resistance through the autonomic nervous system.