Association between splenectomy and portal hypertension in the development of pulmonary hypertension

Both portal hypertension and splenectomy are risk factors for pulmonary hypertension. However, the interactions between portal hypertension and splenectomy in the development of pulmonary hypertension remain unclear. Twelve newly diagnosed pulmonary hypertension patients with a previous history of splenectomy induced by portal hypertension were recruited between November 2008 and May 2017. We compared their clinical features, hemodynamics, and prognosis with idiopathic pulmonary arterial hypertension patients, who were matched by cardiac index, mean pulmonary arterial pressure, and pulmonary vascular resistance. We also compared the clinical characteristics of portal hypertension-post-splenectomy-pulmonary hypertension patients with eight portopulmonary hypertension patients. Compared with the matched idiopathic pulmonary arterial hypertension patients, the portal hypertension-post-splenectomy-pulmonary hypertension patients showed significantly wider red blood cell distribution width (16.7 ± 2.8% versus 13.3 ± 1.7%, p = 0.004), higher total bilirubin concentration (31.0 ± 13.8 µmol/l versus 18.9 ± 10.0 µmol/l, p = 0.010), and higher lactate dehydrogenase concentration (321.5 ± 41.2 IU/l versus 229.2 ± 69.4 IU/l, p = 0.001). Kaplan-Meier survival analyses showed that the portal hypertension-post-splenectomy-pulmonary hypertension patients tended to have poorer prognosis than the matched idiopathic pulmonary arterial hypertension patients (log-rank test: p = 0.010). Compared with the portal hypertension-post-splenectomy-pulmonary hypertension patients, the portopulmonary hypertension cohort appeared to exhibit poorer clinical conditions, including significantly lower mixed venous oxygen saturation (62.9 ± 8.0% versus 73.9 ± 6.5%, p = 0.004) and a significantly higher proportion of pericardial effusion (75.0% versus 8.3%, p = 0.004), even though the two cohorts showed similar hemodynamics. The mean intervals from diagnosis of portal hypertension to pulmonary hypertension in portopulmonary hypertension patients were significantly shorter than the intervals from splenectomy to diagnosis of pulmonary hypertension in portal hypertension-post-splenectomy-pulmonary hypertension patients (5.5 ± 5.2 years versus 13.1 ± 5.9 years, p = 0.008). Splenectomy might be involved in the initiation and development of pulmonary hypertension in patients with portal hypertension, although the precise mechanisms involved remain unknown. Portal hypertension-post-splenectomy-pulmonary hypertension patients might have poorer prognosis even with mild hemodynamics.