Atrial Septostomy Decreases Sympathetic Overactivity in Pulmonary Arterial Hypertension

Background We have reported previously that the sympathetic nervous system is activated in patients with pulmonary arterial hypertension (PAH), and that this is only partly explained by a decrease in arterial oxygenation. Possible causes for increased muscle sympathetic nerve activity (MSNA) in patients with PAH include right atrial distension and decreased cardiac output. Both may be improved by atrial septostomy, but this intervention also further decreases arterial oxygenation. In the present study, we wanted to investigate the effect of atrial septostomy on MSNA in patients with PAH. Methods We recorded BP, heart rate (HR), arterial O2 saturation (Sao2), and MSNA before and after atrial septostomy in PAH patients (mean [± SE] age, 48 ± 5 years) and in closely matched control subjects. Measurements were also performed after septostomy, while Sao2 was brought to the preprocedure level by supplemental O2 therapy. Results Compared to the control subjects (n = 10), the PAH patients (n = 11) had a lower mean BP (75 ± 2 vs 96 ± 3 mm Hg, respectively; p Conclusions Atrial septostomy in PAH patients decreases sympathetic hyperactivity despite an associated decrease in arterial oxygenation, and this appears to be related to decreased right atrial distension.