Quantification of Right Ventricular Electromechanical Dyssynchrony in Relation to Right Ventricular Function and Clinical Outcomes in Children with Repaired Tetralogy of Fallot.

BACKGROUND: Electromechanical dyssynchrony occurs ubiquitously following tetralogy of Fallot (TOF) repair, manifesting electrically as a wide QRS duration and mechanically as a right-sided septal/apical flash. Early septal activation and prestretch of the right ventricular (RV) basal lateral wall followed by its postsystolic shortening contributes to inefficient RV mechanics. However, a right-sided septal flash is a dichotomous finding, and the severity of RV dyssynchrony as a continuous spectrum in relationship to RV dysfunction and clinical outcomes in patients with repaired TOF has not been studied. The aim of this study was to quantify the severity of electromechanical dyssynchrony in relation to RV remodeling and clinical outcomes in a pediatric cohort following TOF repair. METHODS: A retrospective analysis was performed in 81 children with RV volume loading after TOF repair, aged 13.6 ± 2.9 years, and compared with 50 matched control subjects. RESULTS: Patients had higher RV basal-lateral prestretch and postsystolic strain amplitude and duration, RV mechanical dispersion, and basal lateral-septal wall delay compared with control subjects (P < .001 for all). All intra-RV dyssynchrony timing parameters were associated with reduced cardiac magnetic resonance-derived RV ejection fraction and/or echocardiography-derived RV longitudinal strain. Prestretch duration as a percentage of total shortening time and RV basal lateral-to-midseptal delay were independently associated with RV dysfunction. Postsystolic strain amplitude was higher in patients with ventricular arrhythmias compared with arrhythmia-free patients (7.8% [4.2%-13%] vs 2.0% [0%-12.5%], P = .03). CONCLUSION: RV prestretch duration, postsystolic strain, and RV lateral-septal delay quantify RV electromechanical dyssynchrony severity and reflect the underlying pathophysiology. The prestretch duration percentage and RV basal lateral-to-midseptal delay were independently associated with RV dysfunction, potentially providing a clinical tool to quantify RV electromechanical dyssynchrony.

Pulmonary Vein Doppler Patterns in Infants with Single Right Ventricle Anomalies After Initial Staged Palliations.

The aim of this study was to describe serial changes in echocardiographic Doppler pulmonary vein flow (PVF) patterns in infants with single right ventricle (RV) anomalies enrolled in the Single Ventricle Reconstruction trial. Measurement of PVF peak systolic (S) and diastolic (D) velocities, velocity time integrals (VTI), S/D peak velocity and VTI ratios, and frequency of atrial reversal (Ar) waves were made at three postoperative time points in 261 infants: early post-Norwood, pre-stage II surgery, and 14 months. Indices were compared over time, between initial shunt type [modified Blalock-Taussig shunt (MBTS) and right ventricle-to-pulmonary artery shunt (RVPAS)] and in relation to clinical outcomes. S velocities and VTI increased over time while D wave was stable, resulting in increasing S/D peak velocity and VTI ratios, with a median post-Norwood S/D VTI ratio of 1.14 versus 1.38 at pre-stage II and 1.89 at 14 months (P < 0.0001 between intervals). MBTS subjects had significantly higher S/D peak velocity and VTI ratios compared to RVPAS at the post-Norwood and pre-stage II time points (P < 0.0001) but not by 14 months. PVF patterns did not correlate with survival or hospitalization course at 1 year. PVF patterns after Norwood palliation differ from normal infants by having a dominant systolic pattern throughout infancy. PVF differences based upon shunt type resolve by 14 months and did not correlate with clinical outcomes. This study describes normative values and variations in PVF for infants with a single RV from shunt-dependent pulmonary blood flow to cavopulmonary blood flow.

Echocardiographic assessment of right ventricular volumes: a comparison of different techniques in children after surgical repair of tetralogy of Fallot.

AIMS: Different echocardiographic techniques are available for assessing right ventricular (RV) volumes but their clinical validity has not been well established. We compared the feasibility, reproducibility and accuracy of three different echocardiographic techniques for measuring RV volumes and ejection fraction (EF) in children after tetralogy of Fallot (TOF) repair. METHODS AND RESULTS: Seventy patients (age 14.2 ± 7.3 years) were studied using three-dimensional (3D) volume acquisition analysis (Tomtec, Germany), 2D echo with knowledge-based 3D reconstruction (3DR) (Ventripoint, USA) and the four-chamber area (4C area) methods. Parameters analysed were RV end-diastolic volume (EDV), end-systolic volume and EF. Magnetic resonance imaging (MRI) data were available in 41 patients. Intra- and inter-observer as well as inter-technique variability was assessed using Pearson's correlation analysis (R), coefficient of variance, and Bland-Altman analysis. Feasibility was good for all echo techniques (91% for the 3D, 98% for the 3DR, and 100% for the 4C area method). Intra- and inter-observer variability was low for both 3DR and the 3D echo, while more variability was observed for the 4C method. Compared with MRI volumes, 3DR and 3D underestimated EDV by 6.6 ± 10 and 18.2 ± 17.8 mL, respectively, (P < 0.001), while the 4C area method overestimated the EDV by 9.6 ± 33 mL, not significant due to a wide range. CONCLUSION: Current echocardiographic techniques to assess RV volumes are highly feasible and reproducible in paediatric post-operative TOF patients. When compared with MRI measurements, 3DR was the most accurate technique but requires extra equipment that is not readily available.