Left ventricular diastolic function influences right ventricular - Pulmonary vascular coupling in premature infants

Introduction: Reduced left ventricular (LV) diastolic function can exert significant load to the right ventricle (RV) that can affect RVpulmonary vasculature (PV) coupling. RVPV can be assessed with the RV lengthforce relationship (tricuspid annular plane systolic excursion [TAPSE] to pulmonary artery acceleration time [PAAT] ratio). We aimed to determine the association between LV diastolic function measured using tissue Doppler imaging (TDI) and TAPSE/PAAT. Methods: A study of premature infants <29 weeks gestation. TAPSE/PAAT, LV e' and a' waves were measured on Day 1 following birth. Correlation between diastolic indices and TAPSE/PAAT was performed. The independent effect of LV diastolic function and TAPSE/PAAT was assessed using linear regression. Results: One hundred and sixty-two infants with a mean +/- SD gestation & birthweight of 26.6 +/- 1.5 weeks & 938 +/- 241 g. There was a significant positive correlation between LV e' (r = 0.44, p < 0.01)/LV a' (r = 0.44, p < 0.01) and TAPSE/PAAT. This relationship remained significant when adjusting for important confounders (all p < 0.01). Infants with LV a' values in the lowest quartile had lower TAPSE values (4.2 +/- 1.2 vs. 5.1 +/- 1.1 mm, p < 0.01) without a difference in PAAT (41 +/- 8 vs. 41 +/- 10 ms, p = 0.97). Conclusions: We observed a direct correlation between LV diastolic function and RVPV coupling in the first day of age, highlighting the importance ventricular interdependence in premature infants. TAPSE/PAAT, as the index of the RVPV interaction may be further explored for its potential to assess RV reserve under stress with preterm infants in health and disease.