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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Noninvasive cardiac output measurement at rest and during exercise in pediatric patients after interventional or surgical atrial septal defect closure.

In the majority of patients, secundum atrial septal defects (ASDs) are treated interventionally or surgically, before the onset of clinical symptoms, between 3 and 6 years of age. Because right-ventricular dimensions usually normalize after ASD closure, it has been assumed that cardiac function and exercise performance also normalize at long-term follow-up. The aim of our study was to determine cardiac index (CI) at rest and during exercise at medium-term follow-up of children who had undergone surgical or interventional closure of ASD because no such reports have been published thus far. Seventeen patients (age range 8.8-17.3 years) who underwent surgical correction were included together with 17 subjects who received an interventional procedure with Amplatzer and Helex occluders (age range 12.2-17.3 years). The study was performed after a median interval of 8.6 years (range 6.5-11.6) after the procedure. Twelve healthy children of comparable age served as controls. CI measurements were performed based on the inert gas-rebreathing method with the Innocor system. For exercise testing, the standard treadmill protocol of the German Society of Pediatric Cardiology was used. CI, stroke volume (SV), and heart rate (HR) were determined at rest and at two standardized submaximal exercise levels (levels 3 and 6). CI increased in all subjects under exercise conditions. Neither SV nor HR displayed significant differences between the three groups either at rest or under exercise conditions. Although HR increased continuously, no increase of indexed SV occurred beyond level 3. Noninvasive determination of CI at rest and during exercise with the IGR method is feasible in the pediatric age group. At medium-term follow-up, we found no significant differences between patients who underwent surgical or interventional ASD closure compared with normal controls.

Impact of restrictive physiology on intrinsic diastolic right ventricular function and lusitropy in children and adolescents after repair of tetralogy of Fallot.

BACKGROUND: Restrictive right ventricular (RV) physiology is a phenomenon considered potentially beneficial when detected in children and adolescents with repaired tetralogy of Fallot (ToF). It is typically characterised by antegrade flow in the pulmonary artery in late diastole at the time of atrial contraction. However, little is known about the impact of restrictive physiology on intrinsic diastolic RV function or lusitropy. METHODS: Diastolic function was prospectively assessed at baseline level and during dobutamine infusion using the pressure-volume conductance system. End diastolic forward flow in the pulmonary artery was measured by MRI. RESULTS: Twenty-five patients aged 17.9±7.5 years were studied. Although the end diastolic RV pressure, the time constant of isovolumic RV relaxation (τ) and dP/dtmin were similar between both groups, the slope of the end diastolic pressure-volume relationship (Eed) was significantly higher in the restrictive group indicating increased diastolic stiffness in these patients (0.14±0.05 vs 0.06±0.01, p=0.03). Dobutamine stress, however, led to an increase in Eed in the entire ToF cohort indicating an abnormal diastolic response to catecholamines in these patients. CONCLUSIONS: Diastolic RV stiffness of repaired ToF patients with restrictive physiology is increased. The lusitropic response of the RV to ß adrenergic agents is abnormal after ToF repair regardless of whether restrictive physiology is present or not. This has potential implications, particularly for postoperative drug management.