Systemic arterial stiffness in infants with bronchopulmonary dysplasia: potential cause of systemic hypertension

OBJECTIVE: Systemic hypertension is common among preterm infants with severe bronchopulmonary dysplasia (BPD); the exact cause is unknown. The objective of this preliminary hypothesis generating study was to examine systemic arterial structure and vasomotor function in a cohort of preterm infants with severe BPD, using a cohort of preterm infants without BPD and a cohort of term infants for comparison. STUDY DESIGN: After obtaining informed consent, we measured aortic wall thickness and vasomotor function by ultrasonography in 20 infants with severe BPD, 7 infants with no BPD, and compared them with 20 healthy term infants. RESULTS: Maximum aortic thickness was significantly higher in infants with BPD (827 +/- 163 mu m) compared to those with no BPD (674 +/- 22 mu m) and term infants (657 +/- 67 mu m) (unadjusted P<0.0001). The input impedance was similarly elevated in the infants with BPD (574 +/- 127 dynes s cm(-)5) compared to those with no BPD (325 +/- 24 dynes s cm(-5)) or term infants (328 +/- 113 dynes s cm(-5)) (unadjusted P<0.0001). Stiffness index was significantly higher in the infants with BPD (3.4 +/- 0.6) compared to those with no BPD (2.6 +/- 0.3) or term infants (2.3 +/- 0.4) (unadjusted P<0.0001). Systemic vascular resistance was also significantly elevated in the infants with BPD. The results remained significant even after adjusting for gestational age and birth weight. Measures of vasomotor function significantly correlated with blood pressure. CONCLUSION: The aortic wall thickness and vasomotor function are significantly altered in preterm infants with severe BPD. These findings may explain the higher incidence of systemic hypertension in this population.