CARDIAC EFFECTS OF DEXAMETHASONE IN VERY-LOW-BIRTH-WEIGHT INFANTS

Objective. To characterize the cardiac effects of dexamethasone in ver y low birth weight infants. Design. Prospective, randomized, placebo-c ontrolled, double-blind trial. Enrolled subjects were randomized to re ceive either a 42-day tapering course of dexamethasone or a saline pla cebo. Echocardiographic measurements were obtained on days 0, 7, 14, 2 8, and 42. Subjects. Thirteen infants received dexamethasone and 13 a saline placebo. The two groups were similar in birth weight, gestation al 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 wal l thickness on day 14. A significantly lower left ventricular end-dias tolic dimension in the dexamethasone group was initially noted on day 7 and persisted until day 42. With the reduced left ventricular end-di astolic dimension, no significant differences in LV mass were noted, d espite the increased wall thickness. No differences in LV systolic fun ction, as assessed by area shortening, were seen. Assessment of diasto lic function showed a significant increase in the atrial portion of mi tral inflow in dexamethasone patients on day 14, as well as a signific ant prolongation in isovolumic relaxation lime on days 7, 14, and 28. Conclusions. Infants receiving dexamethasone developed evidence for im paired LV filling with a larger increase in wall thickness but no incr ease in LV mass, asymmetric septal hypertrophy, or augmented systolic function. This suggests that alterations in left ventricular filling p lay an important role in the development of hypertrophy seen with dexa methasone administration.