Cardiac Effects of Dexamethasone in Very Low Birth Weight Infants

Objective. To characterize the cardiac effects of dexamethasone in very low birth weight infants. Design. Prospective, randomized, placebo-controlled, double-blind trial. Enrolled subjects were randomized to receive either a 42-day tapering course of dexamethasone or a saline placebo. Echocardiographic measurements were obtained on days 0, 7, 14, 28, and 42. Subjects. Thirteen infants received dexamethasone and 13 a saline placebo. The two groups were similar in birth weight, gestational age, age at enrollment, and sex/race composition. Results. Patients receiving dexamethasone had a significantly larger increase in septal thickness on days 7, 14, and 28 and left ventricle (LV) posterior wall thickness on day 14. A significantly lower left ventricular enddiastolic dimension in the dexamethasone group was initially noted on day 7 and persisted until day 42. With the reduced left ventricular end-diastolic dimension, no significant differences in LV mass were noted, despite the increased wall thickness. No differences in LV systolic function, as assessed by area shortening, were seen. Assessment of diastolic function showed a significant increase in the atrial portion of mitral inflow in dexamethasone patients on day 14, as well as a significant prolongation in isovolumic relaxation time on days 7, 14, and 28. Conclusions. Infants receiving dexamethasone developed evidence for impaired LV filling with a larger increase in wall thickness but no increase in LV mass, asymmetric septal hypertrophy, or augmented systolic function. This suggests that alterations in left ventricular filling play an important role in the development of hypertrophy seen with dexamethasone administration.