RESUMEN
This study was designed to determine the prevalence of trabecular ventricular septal defect (t-VSD) in neonates and to evaluate the effects of its location, morphologic features, and size on its natural course during infancy. One thousand twenty-eight term newborn infants were examined by color Doppler flow imaging with orthogonal ultrasonographic views. Ten girls and 11 boys (2.0%) were found to have t-VSD. The natural course of the defect was examined in 42 consecutive cases, consisting of this group of 21 neonates and another group of 21 neonates with t-VSD. The morphologic features of the defect within the trabecular septum were classified as one or two defects (36 cases) and as a mesh-like defect (six cases). Reduction in size began from the right ventricular side or from within the trabecular septum. Spontaneous closure occurred most commonly during the first 6 months of life and was observed in 32 cases (76%) by 12 months of age: the frequency of closure was not related to the morphologic features and the initial size of the defect, but apical defects tended to have higher persistent patency than did defects in other locations (p less than 0.05). We conclude that the frequency of t-VSD in neonates and the frequency of spontaneous closure during early infancy are higher than previously believed. This information is important for predicting the natural course of t-VSD and deciding on its proper management.
Asunto(s)
Ecocardiografía , Defectos del Tabique Interventricular/diagnóstico por imagen , Velocidad del Flujo Sanguíneo , Ecocardiografía Doppler , Femenino , Defectos del Tabique Interventricular/patología , Defectos del Tabique Interventricular/fisiopatología , Tabiques Cardíacos/patología , Humanos , Lactante , Recién Nacido , MasculinoRESUMEN
Using pulsed Doppler and two-dimensionally directed M-mode echocardiographic techniques, we measured left ventricular (LV) output, stroke volume, heart rate, LV end-diastolic dimension (LVEDD), LV end-systolic dimension, and LV percent fractional shortening (%FS) in 34 normal term infants 12 to 24 hours before parturition and thereafter serially 1, 24, and 96 hours after birth. Stroke volume was calculated as the product of the aortic flow velocity integral and aortic valve area. There was a twofold increase in LV output 1 hour after birth (fetal 170 +/- 46 ml/min/kg vs 1 hour 327 +/- 66 ml/min/kg; p less than 0.01) which was associated with significant increases in stroke volume, %FS, and LVEDD (stroke volume 1.21 +/- 0.33 ml/kg vs 2.25 +/- 0.37 ml/kg; %FS 34.3% +/- 5.8% vs 37.7% +/- 5.4%; LVEDD 15.4 +/- 1.1 mm vs 17.7 +/- 1.4 mm). Heart rate did not change 1 hour after birth. During the subsequent hours after birth, LV output decreased significantly to a value of 245 +/- 56 ml/min/kg (p less than 0.01) at 24 hours, which did not change 96 hours after birth. There were significant declines in stroke volume, LVEDD, and heart rate 24 hours after birth (stroke volume 2.02 +/- 0.42 ml/kg; LVEDD 17.0 +/- 1.1 mm; heart rate 121 +/- 11 beats/min). The %FS remained unchanged within the first 96 hours of age. These results indicate that the major regulator of LV output immediately after birth is stroke volume and not heart rate. The increase in stroke volume is related to an increase in LV size and LV myocardial contractility. Our data provide a useful basis for the interpretation of abnormal LV function in the early neonatal period.
Asunto(s)
Gasto Cardíaco/fisiología , Corazón Fetal/crecimiento & desarrollo , Función Ventricular Izquierda/fisiología , Conducto Arterial/ultraestructura , Ecocardiografía , Femenino , Corazón Fetal/ultraestructura , Frecuencia Cardíaca/fisiología , Frecuencia Cardíaca Fetal/fisiología , Humanos , Recién Nacido , Embarazo , Estudios Prospectivos , Valores de Referencia , Volumen Sistólico/fisiologíaRESUMEN
To elucidate the mechanism involved in closure of the ductus arteriosus (DA), 50 normal full-term infants were examined with two-dimensional and pulsed Doppler echocardiography. The examinations were performed initially within 1 hour after delivery and serially for 3 days. The two-dimensionally derived long-axis plane of the DA disclosed a characteristic localized protrusion into its lumen in 30% of the subjects within 1 hour, in 80% by 4 hours, in 96% by 8 hours, and in all by 24 hours after birth. In 10 infants in whom the intraluminal protrusion did not appear within 4 hours after birth, none had any recognizable changes in the inner diameter or length of the DA during this initial period. The development of the intraluminal protrusion resulted in localized narrowing of the ductal lumen. Doppler echocardiography revealed a high-velocity jet within and downstream from the narrowed portion of the DA. Thereafter, ductal narrowing progressed along the entire length. The intraluminal protrusion may be early evidence of ductal changes leading to eventual functional and anatomic closure.