No abstract available.
Echocardiography* ; Hemodynamics*

No abstract available.
Female ; Fetal Heart* ; Fractals* ; Heart Rate, Fetal* ; Pregnancy

BACKGROUND: Low frequency oscillation of systemic artery pressure was known as the marker of sympathetic modulation. Recently the low frequency oscillation of pulmonay artery pressure in pulmonary hypertensive patient was reported. But no further study about its quantitative relationshop and phasic coupling between the low frequency oscillation of pulmonary artery pressure and systemic artery pressure. Power spectral analysis with autoregressive algorithm and cross spectral analysis are powerful tool for investigation these relationship. METHOD: Analog signals of simultaneous measured left pulmonary and femoral artery pressure in thirty one patients with ventricular septal defect were digitized and stored. After modeling each time series with autoregressive algorithm, power spectral density function was obtained by calculation the frequency response function of each model, and then low frequency power was computed. Cross spectral density function provided squared coherence and phase spectrum. Phase between the low frquency oscillation of the two signal was measured from the phase spectrum when the squared coherence is above 0.5. RESULTS: The advantage of using autoregressive model was that the power spectral density function was continous and sharp spectral peak was usually found. In patients with Rp/Rs<0.25, the low frquency power of pulmonary artery pressure(12+/-12) was significantly smaller than that of the systemic artery pressure(144+/-242). In patients with Rp/Rs>or=0.25, there was no significant difference between the low frequency power of pulmonary artery pressure(384+/-461) and that of the systemic artery pressure(752+/-1241). In patients with Rp/Rs>or=0.25, it was more probable that low frequency oscillation of pulmonary and systemic artery pressure was timely coherent(sqaured coherence>0.5) than in patient with Rp/Rs<0.25. And their phase difference was 0~1.96 radian. CONCLUSION: Autoregressive algorithm is a more powerful tool for spectral analysis than the method of conventional spectrum estimation. When pulmonary vascular resistance remains low, the low frequency oscillation of pulmonary artery pressure was negligible compared to systemic artery pressure. But as pulmonary vascular resistance elevates, the low frequency power of pulmonary artery pressure is much the same as that of systemic artery pressure, and there is a explicit time realtionship that pulmonary artery pressure leads the systemic artery pressure about 0~3 seconds in the low frequency range.
Arteries ; Femoral Artery ; Heart Septal Defects, Ventricular ; Humans ; Hypertension, Pulmonary ; Pulmonary Artery ; Pulmonary Circulation* ; Vascular Resistance

No abstract available.
Purpura, Schoenlein-Henoch* ; Scarlet Fever*

No abstract available.
Heart Septal Defects, Ventricular* ; Tetralogy of Fallot*

BACKGROUND: We studied how periodic and complex heart rate dynamic changes as pulmonary artery pressure increases in 32 infants with ventricular septal defet. In addition, we tested the possibility that the dynamical changes can be used to noninvasively predict the pulmonary artery pressure. METHODS: During cardiac catherterization, mean pulmonary artery pressure was measured and, at the same time, 5minute segments of continous electrocardiographic recording was stored. High-(>0.15 hertz) and low-(0.03-0.15 hertz) frequency components of heart rate variability were computed using spectral analysis. Yhe overall complexity of heart rate time series was quantified by its approximate entropy. RESULT: Pulmonary hypertensive infants(mean pulmonary artery pressure>20mmHg, n=17) had significantly lower low-(p<0.05)and high-(p<0.05) frequency power and lower approximate entropy(p<0.0001) than pulmonary normotensive infants(mean pulmonary artery pressure20mmHg, n=15). The mean pulmonary artery pressure was significantly correlated not with the spectral powers but with approximate entropy(=-0.51, P=0.0001). Conclusion: It can be concluded that, in infants, pulmonary hypertension induced by left-to-right shunt lesions suppress both periodic and complex heart rate oscillation and that mean pulmonary artety pressure can be predicted by calculating approximate entropy of heart trate variability.
Electrocardiography ; Entropy ; Heart Rate* ; Heart Septal Defects, Ventricular* ; Heart* ; Humans ; Hypertension, Pulmonary ; Infant* ; Pulmonary Artery*

OBJECTIVES: This study is aimed to quantify the complex dynamics of beat-to-beat fetal heart rate(FHR) fluctuations by using approximate entropy(ApEn) which is a recently developed mathematical formula quantifying regularity and also to determine the differences between normal fetuses and growth retarded fetuses. BACKGROUND: Recently, some measures of heart rate variability and nonlinear "complexity" of heart rate dynamics have been used as indicators fetal well-being. Approximate entropy is a new mathematical approach and formula to quantify regularity in data. It has been shown to provide new information in fetal heart rate analysis. Because growth retarded fetus accounts for a significant increase in perinatal morbidity and mortality, than normal fetus, we postulated that there existed important differences between normal fetuses and growth retarded fetuses. METHODS: We analyzed FHR tracings for 40 minutes, and approximately 5,000 points in normal fetuses(n=315) and growth retarded fetuses(n=76). The overall "complexity" of each FHR time series was quantified by its approximate entropy, measure of regularity derived from nonlinear dynamics, "chaos theory". RESULTS: Mean baseline FHR increased in growth retarded fetuses than normal fetuses. And the FHR ApEn significantly decreased in growth retarded fetuses(ApEn=0.623) compared to that of the normal fetuses(ApEn=0.868) throughout all gestational ages(p < 0.001). CONCLUSIONS: The ApEn of FHR decreased in growth retarded fetuses throughout all gestational ages. These findings indicated that decreased ApEn values of FHR are associated with sickness and the greater perinatal morbidity risks. Therefore ApEn quantifies subtle changes in FHR regularity and promises for new information in FHR analysis.
Entropy* ; Female ; Fetal Heart* ; Fetus* ; Gestational Age ; Heart Rate ; Heart Rate, Fetal* ; Mortality ; Nonlinear Dynamics ; Pregnancy

The mechanism of vasodilation effect of GS-389, 1-(4'-methoxybenzyl)-6,7 -dimethoxy-1,2,3,4-tetrhydroisoquinoline hydrocholoride, a possible cyclic GMP specific phosphodiesterase inhibitor, on rat and mouse thoracic aorta ring has been investigated. GS-389 relaxed rat and mouse thoracic aorta precontracted with phenylephrine and high K+(60mM) in concentration dependent manner. Presence or absence of endothelium did not alter the relaxing effects of it. GS-389 inhibited Ca2+-induced contraction of the high K+ or 1 uM phenylephrine. Initial phasic contraction induced by phenylephrine and caffeine in Ca2+ free solution was inhibited by GS-389. Methylene blue pretreatment suppressed relaxation effect of GS-389. Relaxation by isoproterenol or sodium nitroprusside and by acetylcholine in endotheilium preserved aorta was potentiated by concurrentadministration of GS-389. GS-389 inhibited phenylephrine-induced phosphatidylinositide hydrolysis. It is suggested that inhibition of phosphoinositide turnover associated with elevated cyclic nucleotide by GS-389 may be the possible vascular relaxation mechanism of it.
Acetylcholine ; Animals ; Aorta ; Aorta, Thoracic ; Caffeine ; Cyclic GMP ; Endothelium ; Hydrolysis ; Isoproterenol ; Methylene Blue ; Mice ; Nitroprusside ; Phenylephrine ; Rats ; Relaxation* ; Vasodilation

No abstract available.
Pulmonary Artery*

PURPOSE: We investigated the autonomic nervous and complex modulation of heart rate and peripheral blood volume, and linear and nonlinear coupling between heart rate and peripheral blood volume in full-term and preterm infants. METHODS: In twenty healthy preterm infants and twenty full-term infants at postconceptional age of 30-37 and 38-41 weeks each, we recorded electrocardiogram and photoplethysmogram simultaneously during sleep in the supine position. To evaluate the autonomic and complex modulation, we performed power spectral analysis and analysis of the univariate nonlinear determinism. To quantify degree of linear and nonlinear couple between heart rates and peripheral blood volume, analyses of cross spectrum and bivariate nonlinear determinism were performed respectively. RESULTS: In the analysis of heart rates, preterm infants had significantly lower normalized high-frequency power (20.3+/-7.7% vs 30.7+/-15.1%, P<0.05), higher low-to high-frequency power ratio (3.0+/-2.1 vs 1.9+/-1.6, P<0.05), and significantly lower univariate prediction error (2.9+/-1.3% vs 4.1+/- 2.8%, P<0.05) when compared to full-term infants. In the analysis of peripheral blood volume, they showed no significant differences. Cross spectrum in all frequency ranges showed no significant difference between them. But preterm infants showed a significantly higher bivariate nonlinear prediction error (4.8+/-3.8% vs 3.1+/-2.2%, P<0.05) and a lower statistical coupling index (16.6+/-10.4 vs 22.9+/-9.2, P<0.05) than full-term infants. CONCLUSION: Compared to full-term infants, the heart rates of preterm infants are less modulated by cardiac parasympathetic activity and less complex. Furthermore, their peripheral blood volume was less nonlinearly coupled to heart rate.
Blood Volume* ; Electrocardiography ; Heart Rate* ; Heart* ; Humans ; Infant ; Infant, Newborn ; Infant, Premature* ; Nonlinear Dynamics ; Perfusion ; Supine Position