Clinical Investigations in Children
Echocardiography in Surgically Repaired Tetralogy of Fallot
Effects of Right Ventricular Hemodynamic Burden on Intraventricular Flow in Tetralogy of Fallot: An Echocardiographic Contrast Particle Imaging Velocimetry Study

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Background

The purpose of this investigation was to test the hypothesis that flow patterns in the right ventricle are abnormal in patients with repaired tetralogy of Fallot (TOF). High-resolution echocardiographic contrast particle imaging velocimetry was used to investigate rotation intensity and kinetic energy dissipation of right ventricular (RV) flow in patients with TOF compared with normal controls.

Methods

Forty-one subjects (16 with repaired TOF and varying degrees of RV dilation and 25 normal controls) underwent prospective contrast imaging using the lipid-encapsulated microbubble (Definity) on Sequoia systems. A mechanical index of 0.4, three-beat high–frame rate (>60 Hz) captures, and harmonic frequencies were used. Rotation intensity and kinetic energy dissipation of flow in the right and left ventricles were studied (Hyperflow). Ventricular volumes and ejection fractions in all subjects were derived from same-day cardiac magnetic resonance (CMR).

Results

Measurable planar maps were obtained for the left ventricle in 14 patients and the right ventricle in 10 patients among those with TOF and for the left ventricle in 23 controls and the right ventricle in 21 controls. Compared with controls, the TOF group had higher RV indexed end-diastolic volumes (117.8 ± 25.5 vs 88 ± 15.4 mL/m2, P < .001) and lower RV ejection fractions (44.6 ± 3.6% vs 51.8 ± 3.6%, P < .001). Steady-streaming (heartbeat-averaged) flow rotation intensities were higher in patients with TOF for the left ventricle (0.4 ± 0.13 vs 0.29 ± 0.08, P = .012) and the right ventricle (0.53 ± 0.15 vs 0.26 ± 0.12, P < .001), whereas kinetic energy dissipation in TOF ventricles was lower (for the left ventricle, 0.51 ± 0.29 vs 1.52 ± 0.69, P < .001; for the right ventricle, 0.4 ± 0.24 vs 1.65 ± 0.91, P < .001).

Conclusions

It is feasible to characterize RV and left ventricular flow parameters and planar maps in adolescents and adults with repaired TOF using echocardiographic contrast particle imaging velocimetry. Intraventricular flow patterns in the abnormal and/or enlarged right ventricle in patients with TOF differ from those in normal young adults. The rotation intensity and energy dissipation trends in this investigation suggest that they may be quantitative markers of RV and left ventricular compliance abnormalities in patients with repaired TOF. This hypothesis merits further investigation.

Section snippets

Study Design

This was a single-center, prospective, clinical study. The institutional review board approved the study protocol. Inclusion criteria consisted of (1) repaired TOF, (2) age ≥ 13 years, (3) absence of any intracardiac shunt on previous imaging studies, and (4) sinus rhythm. Specific exclusion criteria were (1) greater than mild tricuspid valve regurgitation, (2) greater than mild pulmonary valve regurgitation, (3) contraindications to ultrasound contrast, and (4) lack of consent to participate

Results

The study population consisted of 41 subjects: 16 patients with TOF (10 men, six women) and 25 normal adult controls (15 men, 10 women). In the TOF group, 11 patients (69%) had primary repair, and five (31%) had previous shunt palliation before definite repair. Nine patients (57%) were repaired without transannular patches, five (31%) were repaired by the use of transannular patches, and the details of repair were unknown in two (12%). For the TOF group, planar maps suitable for

Discussion

Two-dimensional echocardiography remains the primary imaging modality for repaired CHD, with its excellent temporal and spatial resolution, portability, and low cost.15 Patients with repaired TOF undergo echocardiographic assessments as part of routine follow-up. There is limited experience with contrast echocardiography in children and adults with CHD; however, recent clinical trials have shown that ultrasonic contrast imaging is safe in this population.16

This is the first report of

Conclusions

Characterization of RV and LV flow parameters in patients with TOF is feasible using echocardiographic contrast PIV. It demonstrated that flow patterns in patients with TOF present abnormal properties with higher circulation and reduced energy dissipation that are potentially related to ventricular compliance changes. These insights into RV and LV functional properties in TOF merit further investigation, including evaluation of intraventricular PIV characteristics of the hypertrophic,

Acknowledgments

The authors are grateful to the patients who participated in this study. The authors thank Partho P. Sengupta, MD, for helpful suggestions on image acquisition. The authors also appreciate the assistance of the echocardiography laboratory staff at the University of Nebraska Medical Center.

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    This study was funded by the Children's Hospital and Medical Center Foundation grant. Dr Kutty receives support from the American Heart Association.

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