Tissue-velocity magnetic resonance imaging and tissue Doppler imaging to assess regional myocardial diastolic velocities at the right ventricle in corrected pediatric Tetralogy of Fallot patients.

OBJECTIVES

In patients with corrected Tetralogy of Fallot (cToF), pulmonary regurgitation and subsequent increased right ventricular (RV) end-diastolic volume are diastolic parameters related to adverse outcome. In addition, abnormalities of the RV outflow tract (RVOT) independently promote RV dilatation in cToF patients. Tissue Doppler imaging (TDI) and tissue-velocity magnetic resonance imaging (TV-MRI) enable quantitative assessment of regional diastolic performance by measuring myocardial velocities. Assessment of regional diastolic velocities of the RV may provide insight into the relation between RVOT dysfunction and RV dilatation in cToF patients. The aim of the study was to perform a direct comparison of TV-MRI against TDI to assess regional RV diastolic velocities in cToF patients and control subjects. In addition, the relationship between regional RV diastolic velocities and RV dilatation was investigated.

MATERIALS AND METHODS

Thirty-four cToF patients (8-18 years) and 19 controls were studied. Early (E') and late (A') peak diastolic velocities and E'/A' ratio were assessed with TDI and TV-MRI at the RV free wall and at the RVOT. RV volumes and pulmonary regurgitation were quantified with planimetric and 3-dimensional flow MRI, respectively.

RESULTS

Good correlation and agreement were observed between TDI and TV-MRI at both regions of the RV (RV free wall: E': r = 0.92, mean bias: 0.5 cm/s, A': r = 0.92, mean bias: 0.4 cm/s; RVOT: E': r = 0.92, mean bias: -0.3 cm/s, A': r = 0.95, mean bias: 0.03 cm/s). With both imaging techniques, regional RV diastolic velocities were significantly reduced in cToF patients. The E'/A' ratio at the RVOT (assessed with both TDI and TV-MRI) was related to RV end-diastolic volume, even after correction for pulmonary regurgitation (TDI: P < 0.01, TV-MRI: P = 0.05).

CONCLUSIONS

TDI and TV-MRI can be used interchangeably for the assessment of regional diastolic velocities and performance of the RV in cToF patients and in healthy controls. Regional diastolic velocities at the RVOT are reduced in cToF patients as compared with controls. In addition to pulmonary regurgitation, impaired diastolic performance at the RVOT is independently related to RV dilatation.