Pulmonary hypertension before first and second lung transplantation.

Pulmonary hypertension (PH) is known to occur after lung transplantation particularly in patients who develop obliterative bronchiolitis, the pathological manifestation of chronic allograft rejection (1, 2). Obliterative bronchiolitis is the leading cause of mortality after the first year post-transplantation and is characterized by progressive small airway obstruction with deterioration of graft function (3–7). The term bronchiolitis obliterans syndrome (BOS) is used when the diagnosis is made on the basis of clinical rather than pathologic criteria (8, 9). BOS is defined as a drop in forced expiratory volume in one second (FEV1) of at least 20% of the maximal baseline value after lung transplantation in the absence of other causes of declining FEV1 (8, 10). Lung re-transplantation is the main treatment option for advanced BOS. Previous studies in patients with BOS either used echocardiographic data or did not collect the entire hemodynamic profile during right heart catheterization (RHC) to better characterize the type of PH observed in these patients (1, 11). As such, there are not studies comparing hemodynamic measurements obtained before the first and second lung transplantation. In addition, it is unknown whether the presence of PH before the second lung transplantation has implications in terms of outcomes after re-transplantation. The purpose of the present study was to characterize the type of PH (pre- or post-capillary) (12), compare hemodynamic parameters obtained before the first and second lung transplant, and assess whether the presence of PH before re-transplant correlates with outcomes after the second lung transplantation.