Assessment of myocardial function in late preterm and term infants with transient tachypnea of the newborn using tissue Doppler imaging - a pilot observational study.

The aim of this study was to compare conventional and tissue Doppler echocardiography parameters between transient tachypnea of the newborn (TTN) and healthy control infants. This cross sectional pilot observational study was conducted in a level 3 neonatal care unit of India. Consecutively born late preterm and term infants (LPTI) with TTN were eligible for enrollment. Control group was selected from healthy LPTI. Conventional and tissue Doppler (myocardial velocities, myocardial performance index (MPI)) echocardiography was done within first 12 h (D1) and 48-72 h (D3) of life. Conventional echocardiography parameters were fractional shortening (FS), ejection fraction (EF), ventricular output, E/A ratio, fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), pulmonary artery systolic pressure (PASP), and pulmonary artery acceleration to ejection time ratio (PATET). Baseline characteristics and echocardiography images were compared between TTN and control groups. Out of 60 infants enrolled, 34 from TTN and 20 from control group were finally analyzed. Mean (SD) gestational age and birth weight of the study population was 36(1.8) weeks and 2398(376) g respectively. Left ventricular (LV) parameters were similar between both groups. On D1, right ventricular (RV)e' was smaller (6.42(1) cm/s vs. 7.68(1.68) cm/s, p 0.022), and E/e' (7.79(1.51) vs. 6.08(2.59), p 0.037) was larger in TTN group, indicating RV diastolic dysfunction. RV MPI (0.61(0.11) vs. 0.44(0.12), p < 0.001) was also larger, signifying RV global myocardial dysfunction. Similar findings were observed on D3. PATET was lower in TTN group on both D1 (0.34 (0.05) vs. 0.42 (0.05), p < 0.001) and D3 (0.38 (0.05) vs. 0.43 (0.02), p 0.004) suggesting persistently raised pulmonary arterial pressure, although only 2 infants developed pulmonary hypertension identified by standard echocardiography.   Conclusion: Myocardial tissue Doppler imaging of TTN infants revealed occult right ventricular diastolic dysfunction secondary to persistently raised pulmonary arterial pressure. What is Known: •Transient tachypnea of the newborn may be associated with pulmonary arterial hypertension. What is New: •Tissue Doppler imaging in infants with transient tachypnea of the newborn revealed occult right ventricular diastolic dysfunction secondary to raised pulmonary arterial pressure, not detected by standard echocardiography.