Background: This study aimed to measure and compare right ventricular (RV) function in normal infants and those with pulmonary hypertension (PHT) using the myocardial performance index (RVMPI) and to investigate the relationship between RV function and pulmonary artery pressure.
Methods: A case-control study measured RVMPI in 16 infants with PHT (9 of whom had congenital diaphragmatic hernia) and 28 normal control infants. For the PHT infants, 43 paired measures of RVMPI and pulmonary artery pressure (estimated from tricuspid regurgitation jet velocity) were taken to allow investigation of the relationship between RVMPI and pulmonary artery pressure.
Results: The mean RVMPI for the control infants was 0.24+/-0.09. The RVMPI was significantly elevated in the PHT group (0.55+/-0.17; p<0.0001), including a subgroup of infants with PHT secondary to congenital diaphragmatic hernia (0.58+/-0.18; p<0.0001). The correlation between RVMPI and pulmonary artery pressure in the infants with PHT (R2=0.05; p=0.17) was poor.
Conclusions: In infants, RVMPI allows quantification of right ventricular function and detection of RV dysfunction in PHT. No linear relationship exists between RVMPI pulmonary artery pressure. Use of RVMPI in the clinical setting must take into account the global and load-dependent nature of this measure.