MATURATIONAL CHANGES IN LEFT-VENTRICULAR CONTRACTILE STATE

It has been suggested from animal and human studies that age-related a lterations in left ventricular contractility occur. However, there is little information about growth-related changes in left ventricular pe rformance from preterm infants to older children.In 22 preterm infants , 23 fullterm infants, and 35 children,:eft ventricular contractility was evaluated by two-dimensional and M-mode echocardiography. The rate -corrected mean velocity of fiber shortening (mVcfc)-end-systolic wall stress (ESS) relation was used as an index of contractility. There we re significant inverse linear correlations between ESS and mVcfc in th e three groups tall P<0.01). The slopes and y-intercepts of the regres sion lines of mVcfc-ESS relation were both significantly greater in th e premature infants (mVcfc=-0.0133 ESS+1.62) and neonates (mVcfc=-0.01 07 ESS +1.55) than those in the children (mVcfc=-0.0047+1.29). However , there were no significant differences between the premature and full term infants. Thus, these findings suggest that the contractility and afterload sensitivity of the left ventricle in the premature infants m ay be similar to those in the fullterm infants. In addition, our seria l study in the premature infants showed that the ESS increased signifi cantly with growth while the mVcfc did not change, suggesting that the left ventricular performance in the premature infants during early li fe was preserved in the setting of a lower afterload. (C) 1998 Elsevie r Science Ireland Ltd.