Association of Increased Cardiothoracic Ratio and Intrauterine Growth Retardation

 

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ABSTRACT

Clinical observation suggested an association between an increased cardiothoracic ratio (CT) and growth retardation (IUGR) in the premature neonate. To investigate this hypothesis, a case-control study was performed. Study subjects included 23 cases (IUGR) and 55 control (appropriate for gestational age [AGA]) premature infants with birth-weights 2000 gm or less; Apgar scores greater than 5 at 5 minutes; no congenital heart disease; no polycythemia; no toxoplasmosis, rubella, cytomegalovirus, or herpes infection. In random order, the first chest radiograph of each infant (less than 24 hours) was reviewed by a single radiologist, unaware of the infant's growth status. The CT ratio was computed after measuring the widest internal width of the bony thorax and the cardiac diameter. Mean birthweight (±1 SD) of the IUGR infants was 1161 ± 289 g and of AGA infants was 1401 ±401 g (p < 0.002); the mean gestational ages (±1 SD) were 33.2 ±2.8 and 30.8 ± 2.5 weeks (p < 0.001). Mean CT for IUGR infants was 0.57 ± 0.07 (±1 SD) versus AGA infants, 0.51 ± 0.04 (±1 SD), p < 0.001. When the infants were stratified by growth status and CT ratio, 11 of 23 IUGR and 1 of 55 AGA infants had an increased CT ratio p < 0.0001. When birthweight and gestational age were covaried, growth status remained the best predictor of CT, p = 0.005. There is a strong association of increased CT and growth retardation in premature infants with birthweights 2000 gm or less.