Heart rate variability response to standing in men and women receiving d,l-sotalol following coronary artery bypass graft surgery.

Heart rate variability (HRV), a quantitative marker of autonomic control of heart rate (HR), declines in men and women following coronary artery bypass graft (CABG) surgery. Although d,l-sotalol is prescribed following CABG surgery primarily for its antiarrhythmic effect, its effects on HRV have not been reported; the ß-adrenergic antagonist effect of d,l-sotalol may attenuate sympathetically mediated HR and blood pressure (BP) responses to standing, resulting in postural hypotension. In this study, the HRV response to standing 4 days following CABG surgery in men and women prescribed d,l-sotalol was measured to examine the influence of d,l-sotalol on previously reported HRV responses, taking age and gender into consideration. Participants included 28 men and 10 women who completed testing in supine and standing postures; all had received low-dose d,l-sotalol daily since the first postoperative day. Data included continuous electrocardiograph recording of R-R interval for 10 min in each posture. Participants showed significant effects of standing on the autonomic modulation of HR, as seen by a decrease in parasympathetic indices and R-R interval and an increase in BP. In men, standing decreased parasympathetic modulation and increased the sympathetic nervous system indicator, but previously reported age effects were not seen. In women, standing decreased low frequency power and R-R interval and increased BP, with older women having a smaller increase in BP, suggesting an attenuated response. The differential autonomic nervous system modulation of HR as a function of gender and age after CABG surgery may be attenuated by d,l-sotalol.

Fetal sensitivity to properties of maternal speech and language.

Fetal speech and language abilities were examined in 104 low-risk fetuses at 33-41 weeks gestational age using a familiarization/novelty paradigm. Fetuses were familiarized with a tape recording of either their mother or a female stranger reading the same passage and subsequently presented with a novel speaker or language: Studies (1) & (2) the alternate voice, (3) the father's voice, and (4) a female stranger speaking in native English or a foreign language (Mandarin); heart rate was recorded continuously. Data analyses revealed a novelty response to the mother's voice and a novel foreign language. An offset response was observed following termination of the father's and a female stranger's voice. These findings provide evidence of fetal attention, memory, and learning of voices and language, indicating that newborn speech/language abilities have their origins before birth. They suggest that neural networks sensitive to properties of the mother's voice and native-language speech are being formed.

Fetal behavior in smoking compared to non-smoking pregnant women.

OBJECTIVE: To determine the effects of maternal smoking on fetal spontaneous behavior and auditory processing. METHODS: 38 fetuses of smoking (n=18) and non-smoking (n=20) mothers, stratified by gestational age (<37, >or=37 weeks GA), were examined at least 1h following smoking. Observations included spontaneous fetal heart rate (FHR; 20 min) and body movements (20 min) followed by a 2 min audiotape of the mother reading a story while FHR and body movements were recorded. RESULTS: There were no differences in spontaneous behaviors; full-term fetuses showed a FHR acceleration and body movement during the mother's voice. A FHR response following voice offset was limited to fetuses less than 37 weeks GA of non-smoking mothers. CONCLUSION: Fetuses less than 37 weeks GA of mothers who smoke throughout pregnancy have a delayed onset of response to the maternal voice, a subtle difference which may have implications for later language development for prematurely born infants which needs further investigation.

Fetal development: voice processing in normotensive and hypertensive pregnancies.

Recent observation of maternal voice recognition provides evidence of rudimentary memory and learning in healthy term fetuses. However, such higher order auditory processing has not been examined in the presence of maternal hypertension, which is associated with reduced and/or impaired uteroplacental blood flow. In this study, voice processing was examined in 40 fetuses (gestational ages of 33 to 41 weeks) of hypertensive and normotensive women. Fetuses received 2 min of no sound, 2 min of a tape-recorded story read by their mothers or by a female stranger, and 2 min of no sound while fetal heart rate was recorded. Results demonstrated that fetuses in the normotensive group had heart rate accelerations during the playing of their mother's voice, whereas the response occurred in the hypertensive group following maternal voice offset. Across all fetuses, a greater fetal heart rate change was observed when the amniotic fluid index was above compared to below the median (i.e., 150 mm), indicating that amniotic fluid volume may be an independent moderator of fetal auditory sensitivity. It was concluded that differential fetal responding to the mother's voice in pregnancies complicated by maternal hypertension may reflect functional elevation of sensorineural threshold or a delay in auditory system maturation, signifying functional differences during fetal life or subtle differences in the development of the central nervous system.

Maternal cardiac autonomic function and fetal heart rate in preeclamptic compared to normotensive pregnancies.

BACKGROUND: Preeclampsia during pregnancy increases a woman's risk of cardiovascular disease in two ways. Women who develop preeclampsia are at increased risk for the development of hypertension and cardiovascular disease later in life. As well, fetal adaptations (e.g., growth restriction) may lead to the development of cardiovascular risk factors (e.g., obesity, increased cholesterol) in the offspring. Although atypical maternal cardiac autonomic function has been reported in preeclampsia, to date, its effects on fetal cardiac function have not been determined. PURPOSE: To characterize the pattern of short-term maternal cardiac autonomic modulation and spontaneous fetal heart rate changes in preeclamptic compared to normotensive women and to determine the relationship between them. METHOD: Twenty-seven mother-fetal pairs (n = 9 preeclamptic, n = 18 normotensive) at 32 to 40 weeks gestation were tested on one occasion. Maternal autonomic modulation of heart rate was measured for 20 minutes using electrocardiographic and beat-by-beat arterial systolic blood pressure recordings. Simultaneously, spontaneous fetal heart rate was obtained using a cardiotachograph. Women's cardiac autonomic responses to orthostatic stress were obtained for five minutes in a standing position. RESULTS: Comparisons of maternal cardiac measures in the preeclamptic versus the normotensive group showed that the preeclamptic group had a decreased parasympathetic nervous system indicator and an increased sympathetic nervous system indicator with increasing gestation. In response to orthostatic stress, women in both groups showed a similar increase in arterial systolic blood pressure and a decrease in parasympathetic nervous system indicator and R-R interval when standing compared to lying. Fetuses in the normotensive compared to the preeclamptic group had more spontaneous fetal heart rate accelerations; the greater the decrease in the parasympathetic nervous system indicator from lying to standing, the greater the number of fetal heart rate accelerations. CONCLUSIONS: These findings serve to further our understanding of the cardiovascular pathophysiology of preeclampsia in both the mother and the fetus. Women who develop preeclampsia during pregnancy show atypical autonomic nervous system modulation of heart rate that is associated with a decrease in spontaneous fetal heart rate accelerations in late gestation. Implications for cardiovascular nursing practice include the monitoring of maternal cardiac autonomic function during pregnancy, especially during standing, as well as a need for continued surveillance of maternal cardiovascular function following pregnancy. The negative effect on fetal heart rate accelerations has implications for the interpretation of standardized obstetrical tests of fetal well-being.

Maturation of fetal responses to music.

Maturation of fetal response to music was characterized over the last trimester of pregnancy using a 5-minute piano recording of Brahms' Lullaby, played at an average of 95, 100, 105 or 110 dB (A). Within 30 seconds of the onset of the music, the youngest fetuses (28-32 weeks GA) showed a heart rate increase limited to the two highest dB levels; over gestation, the threshold level decreased and a response shift from acceleration to deceleration was observed for the lower dB levels, indicating attention to the stimulus. Over 5 minutes of music, fetuses older than 33 weeks GA showed a sustained increase in heart rate; body movement changes occurred at 35 weeks GA. These findings suggest a change in processing of complex sounds at around 33 weeks GA, with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses.

An exploratory study of fetal behavior at 33 and 36 weeks gestational age in hypertensive women.

The relationship between maternal blood pressure (BP) and fetal behaviors as well as differential spontaneous and vibroacoustic elicited fetal behaviors were examined in hypertensive (n = 21) compared to normotensive (n = 22) women at 33 and 36 weeks gestational age (GA). Maternal BP was negatively related to GA at birth and birth weight. On average, fetuses of hypertensive women were born 2 weeks earlier (38 weeks GA) and 340 g lighter. Maternal systolic BP was negatively related to the number of spontaneous body movements observed on ultrasound scan over 20 min and the magnitude of the fetal heart rate (FHR) acceleration elicited by a vibroacoustic stimulus. At 36 weeks GA, vibroacoustic stimulation elicited differential responding with fetuses in the hypertensive compared to the normotensive group having fewer body movements, a lower magnitude of FHR acceleration, and a lack of cardiac-body movement coupled responses. These findings suggest a relationship between maternal BP and fetal behaviors and differential functional development of sensory-motor response systems which need to be characterized in the subgroups of hypertensive disorders observed during pregnancy.