Right ventricular–pulmonary arterial coupling in patients after repair of tetralogy of Fallot

Abstract

Right ventricular-pulmonary arterial coupling is an important determinant in the development of right ventricular failure. The purpose of our study was to assess right ventricular-pulmonary arterial coupling in children and adolescents with dilatation of the right ventricle after repair of tetralogy of Fallot. Right ventricular-pulmonary arterial coupling was quantified as the ratio of pulmonary arterial elastance (an index of arterial load) and right ventricular end-systolic elastance (an index of contractility) using pressure-volume loops with conductance catheters at the baseline level and during dobutamine infusion. A total of 24 patients (mean age, 16.7 ± 7.0 years) after tetralogy of Fallot repair were enrolled in the present study. End-systolic elastance showed an appropriate increase under inotropic stimulation from 0.24 ± 0.18 to 0.47 ± 0.39 mm Hg/mL/m(2) (P<.01). Simultaneously, the arterial elastance increased from 0.50 ± 0.28 to 0.72 ± 0.48 mm Hg/mL/m(2) (P<.01). Right ventricular-pulmonary arterial coupling was impaired at rest and did not improve significantly under dobutamine stress in the entire study population (arterial elastance/end-systolic elastance decreased from 3.0 ± 2.8 to 2.7 ± 3.1; P=.70). Patients with transannular patch repair (n=11) showed significant uncoupling in response to dobutamine (arterial elastance/end-systolic elastance increased from 2.0 ± 0.8 to 3.7 ± 4.1), and coupling even improved with dobutamine in patients who had undergone a transatrial approach (arterial elastance/end-systolic elastance decreased from 1.6 ± 1.0 to 0.9 ± 0.6; P=.04). Our study demonstrated that right ventricular-pulmonary arterial coupling is impaired in patients with tetralogy of Fallot and is mainly affected by the surgical strategy used at the primary repair. These results elucidate the emerging role of ventricular-arterial interactions as a contributing mechanism for deterioration in right ventricular performance and impaired response to inotropic drugs in patients with tetralogy of Fallot.