Effect of left ventricular wall mass on Doppler filling patterns in the developing normal human heart

To assess gestational age- and growth-related changes in left ventricular ( LV) size, LV wall, and LV transmitral flow velocity patterns, 5-dimensional (2-D) and Doppler echocardiographic studies were performed in 89 normal fe tuses aged 16 to 38 weeks. Serial studies were designed in 7 fetuses. Varia bles measured from 4-chamber views were chamber areas and myocardial wall a reas. From these measurements, area shortening fraction and ratio of myocar dial wall area to end-diastolic chamber area were calculated. LV end-diasto lic chamber area and myocardial wall area increased exponentially with adva ncing gestational age (r = 0.88 and 0.90, respectively, p <0.001). Area sho rtening fraction showed no significant changes with gestational age. Ratio of myocardial wall area to LV end-diastolic chamber area decreased graduall y with increasing gestational age (r = -0.77, p <0.001). With increasing ge stational age, mitral peak velocities of early diastole increased (r = 0.82 , p <0.01) with little change in peak velocity during atrial contraction. M ultiple regression analysis showed that age-related increases in peak veloc ity of early diastole were related to advancing gestational age and also to decreases in ratio of myocardial wall area to LV end-diastolic chamber are a. Low peak filling velocities during early diastole in younger fetuses may be related partly to relative increase in LV wall mass. The gestational ag e-related decreases in LV wall mass may be one of the important mechanisms of gestational age-related alterations in diastolic properties, especially relaxation processes. (C) 2000 by Excerpta Medica, Inc.