Assessment of Right Ventricular Function Using Tissue Doppler Imaging in Infants with Pulmonary Hypertension

BACKGROUND: In infants with pulmonary hypertension (PHT), right ventricular (RV) function may be altered and contribute to disease severity. Tissue Doppler imaging (TDI) is a new echocardiographic modality which directly measures myocardial velocities and may allow quantitative assessment of systolic and diastolic ventricular function in infants. OBJECTIVE: To measure and compare RV myocardial velocities in infants with PHT and in normal control infants, using TDI. METHODS: This was a prospective case-control study. Twenty-eight control infants and 15 infants with PHT, of whom 11 had congenital diaphragmatic hernia (CDH), were recruited. TDI was used to obtain systolic and diastolic myocardial velocities in the RV and interventricular septum in all infants. RESULTS: There were significant reductions in systolic isovolumic contraction velocity (IVV; 5.3 vs. 6.6 cm/s) and systolic ejection velocity (S; 6.6 vs. 9.2 cm/s) in the PHT group compared to the control group. Early diastolic myocardial velocity, E', was also significantly reduced in the RV in the PHT infants compared to controls (-4.3 vs. 8.6 cm/s). The same significant reductions in systolic and early diastolic TDI velocities were observed in the subgroup of CDH infants alone. CONCLUSIONS: TDI permits non-invasive assessment of RV myocardial velocities in infants. Reduced systolic and diastolic velocities in PHT may represent impaired systolic contraction and early diastolic relaxation. Therapies which target inotropic and lusitropic function may be appropriate in infants with PHT and RV dysfunction. The load-dependency of TDI measures in infants and the effects of specific therapies on RV function in PHT require further investigation.