Characterizing the role of left ventricular indices and biventricular interaction in bronchopulmonary dysplasia-associated pulmonary hypertension in extreme prematurity.

Introduction: Bronchopulmonary dysplasia (BPD) is a common respiratory morbidity in preterm infants. The onset of pulmonary hypertension leads to worse respiratory outcomes. The contribution of left ventricular diastolic dysfunction in BPD-PH is well reported. We evaluated the serial left ventricular (LV) function and possible ventricular interdependence among BPD-PH.

Methods: Single-centre, prospective observational study. Infants <28 weeks of gestation included.

Results: 80 infants were enrolled. The incidence of BPD-PH was 23%. The BPD-PH group had a high incidence of hemodynamically significant ductus arteriosus (83% vs 56%,p <0.018), longer oxygen days (96.2±68.1 vs 59.35±52,p< 0.008), and prolonged hospital stay (133.8±46 vs 106.5±38 days,p<0.005). Serial tissue Doppler imaging showed prolonged left ventricle (LV) isovolumetric contraction time (IVCT)(31.05±3.3 vs 26.8±4.4ms,p<0.001), and myocardial performance index (MPI) (0.43±0.03 vs 0.37±0.04,p<0.001) from 33 weeks. The changes in IVCT (35.9±6.7 vs 27.9±4.5ms, p<0.001), isovolumetric relaxation time (IVRT) (50±6.5 vs 39.9±5.8ms,p <0.001), and MPI (0.48±0.05 vs 0.36±0.03,p <0.001) persisted at 36 weeks. The receiver operator characteristic curve showed LV MPI >40 has 83% sensitivity and 65% specificity (AUC 0.77, p<0.001) in the diagnosis of PH. The BPD-PH group had a higher LV E/E' ratio (13.1±4.4 vs 11.4±3.4, p <0.02). Pearson correlation test showed a moderate positive correlation between RV MPI and LV MPI (r= 0.585, p <0.001).

Conclusions: Significant LV diastolic dysfunction was observed in BPD-PH. This is the first study to show biventricular strain and possible ventricular interdependence in BPD-PH. The prolonged LV IVRT and MPI may be a novel echocardiographic indicator of BPD-PH.