Date of Award

3-24-1999

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Dr. Alan Friedman

Abstract

The purpose of this study is to examine whether iatrogenic hypertrophic cardiomyopathy (HCM) in premature infants might be induced by routine neonatal therapies including the administration of hyperalimentation, dexamethasone, and/or insulin infusion. Infants with gestational age < 32 weeks and birth weight < 1250 grams were studied. Echocardiographic and metabolic analyses were performed before 48 hours of age at enrollment, and again at one, two, three, and five weeks thereafter. Eleven patients were studied with a median gestational age of 26 weeks (range 24-29 weeks) and median birth weight of 804 grams (range 609-1230 grams). All eleven subjects received hyperalimentation, five received dexamethasone, and two received both dexamethasone and an exogenous insulin infusion. The ratio of interventricular septal to left ventricular posterior wall thickness increased significantly from 1.15±0.06 at enrollment to 1.51±0.06 (p<0.05) during the third week of life, consistent with the diagnosis of HCM. This ratio returned to a normal value of 1.17±0.1 by the fifth week of life. C-peptide excreted in the urine peaked during the fourth week of life at 253±99 μg/g creatinine, and a peak in circulating insulin levels to 19±4 μU/ml occurred during the third week of life. Both the excreted C-peptide and circulating insulin levels decreased by the end of the fifth week of life. All results are expressed as the mean±SEM. This preliminary data suggest that the development of a transient hypertrophic cardiomyopathy occurs in premature infants, and appears to resolve as caloric intake, insulin production, and circulating insulin levels decrease.

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