Objective: To investigate the value of Doppler tissue imaging (DTI) in evaluation the changes of cardiac function after neonatal asphyxia.
Methods: Sixty-two full-term neonates suffering from asphyxia at birth were divided into 2 groups according to Apgar scores: severe asphyxia group with the Apgar scores < or = 3 (n = 31) and mild asphyxia group with the Apgar scores > 3 and < or = 7 (n = 31). Thirty normal neonates were used as control group. DTI was conducted 24, 48, and 72 hours after birth to measure the values of systolic peak myocardial motion velocity (DTIs), early diastolic peak myocardial motion velocity (TDIe), late diastolic peak myocardial motion velocity (DTIa) and DTI e/a of anterior leaflet of mitral valve, and the values were compared with the left ventricular ejection fraction (LVEF) measured by M-mode ultrasound and the values of E, A, and E/A of mitral valve shown in pulsed Doppler echocardiography.
Results: The LVEF of the severe asphyxia group measured 24 h after birth was (62 +/- 4)cm/s, significantly lower than that of the control group (P < 0.05), while the values of DTIs 24, 48, and 72 hours of the severe asphyxia group were all significantly lower than those of the control group (all P < 0.05). In the severe asphyxia group the DTIs value 24 hours [(3.9 +/- 0.4) cm/s] after the birth was significantly lower than those 48 and 72 hours after birth [(5.3 +/- 0. 8)cm/s, (5.0 +/- 0.9)cm/s,both P < 0.01]. The values of E and E/A of the severe asphyxia group (55 +/- 12, 0.94 +/- 0.25) 72 h after birth of the mild asphyxia group (51 +/- 10, 0.89 +/-0.20) were both significantly lower than those of the control group (both P < 0.01), the value of A 72 h after birth of the mild asphyxia group (60 +/- 7) was significantly higher than that of the control group (P < 0.01). The values of DTIe and DTIe/a 24, 48, and 72 h after birth of the mild asphyxia group were all significantly lower than those of the control group, and the values of DTIa 24, 48, and 72 h after birth of the mild asphyxia group were all significantly higher than those of the control group (all P < 0.01).
Conclusion: After neonatal asphyxia, both the systolic function and the diastolic function of the left ventricle decrease; and the DTI indexes can reflect the cardiac function changes more sensitively than M-mode ultrasound indexes.