Hemodynamic profiling of patients with a Fontan circulation using pulmonary pressure/flow relations during dobutamine stress and pulmonary vasodilation testing.

The hemodynamics of Fontan pathophysiology and the effects of pulmonary vasodilator therapy are insufficiently understood. The aim was to evaluate hemodynamic responses to dobutamine-induced stress and the effect of concomitant acute pulmonary vasodilation (APV) testing in patients with a Fontan circulation to identify hemodynamic phenotypes. Sixteen adult patients undergoing cardiac catheterization for clinical indication were included. Hemodynamic phenotyping was performed during baseline, dobutamine-induced stress, and concomitant APV [inhaled nitric oxide with fraction of inspired oxygen ([Formula: see text]) 1.0]. Pulmonary vascular disease (PVD) was defined by pulmonary vascular resistance (PVR) > 2 Wood units or pulmonary artery pressure/pulmonary blood flow slope (mPAP/Qp) > 3 mmHg/L/min. Patients were assigned to group A without PVD (n = 8) or group B with PVD (n = 8 mPAP/Qp > 3 with n = 3 PVR > 2). For the total group, median cardiac output (Qs) was 5.2 L/min and increased to 7.3 L/min with dobutamine (P = 0.005) without further change with APV (P = 0.255). However, subgroup analysis revealed that during dobutamine, the increase in Qs occurred only in group A (+3.5 L/min, P = 0.012), and Qs decreased in APV (-1.3 L/min, P = 0.0036). In contrast, in group B, Qs did not change with dobutamine (P = 0.236) nor with APV (P = 0.327). However, in contrast to group A (P = 0.889), in group B, Qp increased with APV (+1.3 L/min, P = 0.017), whereas the mPAP/Qp slope improved significantly (6.2 to 1 mmHg/L/min, P = 0.017). Suggesting that APV improved Qp and oxygenation in patients with PVD but had negative effects in those without PVD. This study shows that hemodynamic response to dobutamine-induced stress and APV differs in patients with a Fontan circulation depending on the presence of pulmonary vascular disease. Hemodynamic phenotyping with sophisticated identification of pulmonary vascular disease potentially allows for patient-tailored treatment.NEW & NOTEWORTHY Hemodynamic response to dobutamine-induced stress and acute pulmonary vasodilation testing differs in patients with a Fontan circulation depending on the presence of pulmonary vascular disease. This study supports that there is no hemodynamic rationale for pulmonary vasodilator therapy for the general Fontan population. The use of mPAP/Qp slopes and acute pulmonary vasodilator testing should be considered to identify pulmonary vascular disease. Hemodynamic phenotyping with the identification of pulmonary vascular disease potentially allows for patient-tailored treatment.