A new look at bronchopulmonary dysplasia post capillary pathophysiology and cardiac dysfunction.

Abstract

Background: In preterm infants, pulmonary hypertension (PH) and right ventricular function are the focus of cardiovascular effects of bronchopulmonary dysplasia (BPD). The impact of left sided (systemic) indices is not well understood. Objective(s): To assess cardiac indices reflecting systemic afterload and pulmonary venous back pressure as pathophysiologic factors in infants with 'severe' BPD. Method(s): Cardiac parameters were measured by conventional echocardiography in 20 preterm infants with severe BPD and compared with 10 preterm infants with no BPD and 20 healthy term infants. Result(s): The gestational age and birthweight amongst preterm infants with and without BPD were comparable (26.2 +/-1.7 vs 26.2+/- 0.6 weeks and 772 +/-271 vs 704+/- 53 g). All the infants belonged to the 'severe BPD' category (need for >= 30% oxygen and/or positive pressure at 36 weeks post menstrual age). None of them were intubated and mechanically ventilated at the time of the study. In infants with severe BPD, PH was noted in [5 (25%), tricuspid regurgitation Doppler jet >=2.8 m/s and 15 (75%), by the Time to peak velocity/Right ventricular ejection time <0.34]. Amongst systemic cardiac indices, significant impairment of diastolic function was noted in the BPD group compared to no BPD infants and term infants. The significance persisted after adjusting for gestational age and birthweight. A higher end systolic wall stress (surrogate for afterload) had a significant correlation with lower mean velocity of circumferential fibre shortening (contractility) (r =-0.74, p= 0.0002). Conclusion(s): Altered systemic (left sided) cardiac function was noted in the infants with BPD which may lead to pulmonary venous congestion contributing to a continued need for respiratory support. Impaired left ventricular relaxation and high left atrial pressure may be oedemagenic factors. (Table Presented).