Left cardiac dimensions and an index of left ventricular performance, the percent shortening of the internal diameter (%SID) of the left ventricle, were evaluated in premature infants who were asymptomatic, others with pulmonary disease and others with patent ductus arteriosus (PDA). In contrast to controls, left atrial and/or left ventricular end-diastolic dimensions were increased in all infants with clinical criteria of significant PDA. Postoperative dimensions decreased significantly. Percent SID values for normal premature infants (m=33.5%; SD=3.5%) and those with pulmonary disease alone did not differ significantly. In those with clinical criteria of PDA, who were subsequently found to have echocardiographic evidence of left cardiac enlargement, values for %SID were increased. As expected %SID values for individual patients represented a wider range of left ventricular function and/or afterload than for controls. Upon spontaneous or surgical closure of the PDA, %SID returned to normal. A PDA which is associated with left cardiac enlargement exhibits increased %SID, whereas decreasing %SID in the presence of increased dimensions suggests deteriorating myocardial performance. Echocardiography provides valuable insight into the cardiac status of these infants and may contribute to their medical and/or surgical management.

While there are no known risks associated with diagnostic ultrasound, uncertainty about the safety of prenatal ultrasound exposure remains. The purpose of the present experiment was to evaluate the behavioral teratogenic potential of continuous-wave (cw) ultrasound in rats, in the absence of maternal anesthesia or restraint. Pregnant CD rats, trained to remain immobile in a water-filled ultrasound exposure tank, were scanned with 3 MHz cw ultrasound at levels of 0, 2, 10, 20, or 30 W/cm2 ISPTA (spatial peak, temporal average intensity) on gestational days 4-20 for approximately 10 min/day. Offspring were examined postnatally for survival, growth, physical landmarks of development, behavioral development, and the adult functions of locomotor activity, learning and memory, and startle reactivity. No effects of prenatal ultrasound were found on maternal characteristics, offspring survival or growth, physical or behavioral landmarks of development, or adult tests of passive avoidance or startle. Effects at the highest intensity were obtained on corner and side locomotor activity and in a multiple-T water maze on measures of errors of commission and time spent finding the goal. The results showed that prenatal cw ultrasound in rats can induce effects on some postnatal neurobehavioral functions at high exposure intensities (30 W/cm2), but at lower intensities (2-20 W/cm2) no consistent evidence of neurobehavioral effects was observed.

While there are no known risks associated with diagnostic ultrasound, uncertainty about the safety of prenatal ultrasound exposure remains. The purpose of the present experiment was to evaluate the teratogenic potential of pulsed-wave (pw) ultrasound in rats, in the absence of maternal anesthesia or restraint. Pregnant CD rats, trained to remain immobile in a water-filled ultrasound exposure tank, were scanned with 3-MHz pw ultrasound at levels of 0, 2, 20 or 30 W/cm2 ISPTA (spatial peak, temporal average intensity) on gestational days 4-19 for approximately 10 min/day. Examination of fetuses on E20 revealed no increase in skeletal or visceral malformations in groups exposed to pw ultrasound in utero. The number of implantations/dam was significantly increased in all pw ultrasound exposure groups compared to sham-exposed animals and, in a possibly related finding, resorptions were increased in the two highest exposure groups. Although significantly increased compared to controls, resorption frequencies in these groups were low (< 10%). No exposure-related changes in fetal weights were observed in offspring of rats scanned with pw ultrasound during gestation. The results indicate that, under the conditions described, no overt embryotoxicity is associated with gestational exposure to pw ultrasound intensities of up to 30 W/cm2.

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