Biomedical subjects

Yasuo Yumoto

Publications and source records attributed to Yasuo Yumoto.

5 recordsLinked to original sources

PubMed2006

Noninvasive measurement of isovolumetric contraction time by Doppler cardiography can be substituted for fetal cardiac contractility: evaluation of a fetal lamb study.

OBJECTIVE: The objective of this study is to clarify whether the isovolumetric contraction time obtained from Doppler cardiography (Doppler ICT) can be an index substituted for fetal cardiac contractility. MATERIALS AND METHODS: In 10 pregnant ewes, fetal hypoxemia was induced by giving a variable mixture of gases. Through experiment, the Doppler ICT, pre-ejection period (PEP), and the maximum first derivative of the left ventricular pressure waveform (Max dp/dt) were simultaneously recorded every 10min. The relationship between both the Doppler ICT and PEP, and the Max dp/dt were analyzed. RESULTS: A significant negative linear regression was founded between the Doppler ICT and the Max dp/dt. A significant negative linear regression was also shown between PEP and the Max dp/dt. Moreover, the regression of Max dp/dt on ICT had significantly less residual variance than the regression of Max dp/dt on PEP (p=0.0004). CONCLUSION: In contrast to PEP, Doppler ICT is a reliable, and non-invasive index which can be substituted for fetal cardiac contractility.

Animals↗

PubMed2006

Simplified ultrasound screening for fetal brain function based on behavioral pattern.

Despite the longstanding conclusion that behavior can reveal aspects of underlying anatomy and function, no generalized antenatal behavior screening has been developed to identify fetuses that may have central nervous system defects requiring further evaluation. We devised a brief ultrasound examination to distinguish fetuses with compromised central nervous system function from the general population and evaluated it with this study. The study design compared behavioral findings obtained by retrospectively reviewing the ultrasound examinations of 5 fetuses that had abnormal behavior with prospectively obtained findings of 29 normal fetuses. Median time for brief examination criteria was 50 min (range, 30-60 min). The only case undetectable by this brief ultrasound examination has an eye-movement period significantly longer than the normal upper limit. Using this method as a screening test may make it possible to include assessment of fetal brain function as part of routine antenatal care.

Central Nervous System↗

PubMed2006

Fetal aortic distension waveforms for evaluating cardiac function and changes in blood pressure: fetal lamb validation.

AIM: To investigate which part of the fetal aortic distension waveform is mainly influenced by changes in fetal cardiac contractility and aortic blood pressure. METHODS: In acute preparation, aortic distension waveforms were recorded using an echo-tracking system, and aortic and left ventricular pressure waveforms were obtained from six late-gestation catheterized fetal lambs. Dobutamine and angiotensin II were separately infused and the correlations between the maximum value in the first derivative of left ventricle pressure waveforms (Max dP/dt) and fetal blood pressure, and the parameters obtained from aortic distension waveforms were analyzed using linear regression analysis. RESULTS: With a change in cardiac contractility, the maximum value of first derivative of the systolic rising slope in the aortic distension waveform had a positive correlation with Max dP/dt (r = 0.93, P < 0.0001). With changes in fetal blood pressure, both the amplitude and the ratio of increase from the end diastolic diameter obtained from the aortic distension waveform had a significant positive correlation with aortic blood pressure amplitude (r = 0.60, P < 0.01; r = 0.61, P < 0.01, respectively). CONCLUSION: The maximum first derivative of the systolic rising slope in the aortic distension waveform and the amplitude in the aortic distension waveform enable us to non-invasively substitute for fetal cardiac contractility and aortic blood pressure amplitude, respectively.

Animals↗

PubMed2005

Noninvasive measurement of isovolumetric contraction time during hypoxemia and acidemia: Fetal lamb validation as an index of cardiac contractility.

OBJECTIVES: The objectives of this study are firstly to clarify how the Doppler isovolumetric contraction time (ICT) is influenced by arterial oxygen pressure (PaO2) or pH, and secondly to confirm the relationship between the Doppler ICT and myocardial contractility during hypoxemia and/or acidemia in the fetal lamb. MATERIAL AND METHODS: In 12 pregnant ewes, fetal hypoxemia and acidemia were induced by giving ewes a variable mixture of gases for 120 min. The chronological change of fetal PaO2, pH, Doppler ICT and maximum first derivative of the left ventricular pressure waveform (Max dp/dt) was recorded every 30 min. RESULTS: Doppler ICT and PaO2 had no significant regression. On the other hand, Doppler ICT and pH demonstrated a significant negative regression. Moreover, one critical given pH point was indicated with statistical significance at 7.20 and the prolongation of the Doppler ICT was found more markedly in the range below the pH of 7.20 compared with the range above 7.20. A significant negative linear regression was found between the Doppler ICT and the Max dp/dt. CONCLUSION: The measurement of Doppler ICT enables us to predict severe acidosis and a decrease of myocardial contractility in the fetus.

Acidosis↗

PubMed2004

Prenatal diagnosis of slow-rate ventricular tachycardia using fetal electrocardiography.

OBJECTIVES: We report a case in which fetal ventricular tachycardia (VT) could be diagnosed, in utero, using a transabdominal fetal electrocardiogram (fECG) with motion-mode (M-mode) echocardiography. METHODS: The fetus was referred at 32 weeks' gestation due to tricuspid atresia. The fetal cardiotocogram demonstrated paroxysmal tachycardia with a ventricular rate of 155 to 160 bpm within the confines of normal sinus rhythm. RESULTS: M-mode echocardiography showed atrioventricular dissociation with a rather slow ventricular rate. To identify the level of the ectopic focus for tachyarrhythmias, we attempted to detect the electrical signals of the fetal heart and succeeded in recording the fECG. Morphological assessment of the fECG allowed for the extraction of both the normal QRS complex and apparently dissimilar ectopic QRS beat, which has a different polarity despite a relatively similar width. CONCLUSION: Consequently, the case proved to have VT at a slow rate, probably originating from the focus near the atrioventricular junction inside the ventricle.

Adult↗