Tadahiko Ito

Effect of Heart Rate on Left Ventricular Diastolic Filling Patterns Assessed by Doppler Echocardiography in Normal Infants

Abstract In conclusion, this study shows that physiologic HR changes cause significant alteration in transmitral Doppler flow velocity patterns, and indicates that such changes should be considered when using Doppler echocardiography to assess diastolic properties.

Effects of Low-Dose Dobutamine on Left Ventricular Diastolic Filling in Children

To investigate the effects of dobutamine on the Doppler transmitral flow pattern in children with normal left ventricular function, Doppler echocardiography was used to measure the transmitral flow in 14 healthy children before and during infusion of dobutamine (5 μg/kg per minute). Cardiac output was measured by the thermodilution method, and stroke volume was calculated as the cardiac output divided by the heart rate. Dobutamine increased the peak velocity and flow velocity-time integral of early diastolic filling without changing those of atrial contraction and normalized peak velocity of early diastolic filling, suggesting an increase in left ventricular relaxation. Dobutamine increased the stroke volume and rate-corrected mean velocity of fiber shortening with reduced end-systolic wall stress, indicating an increase in left ventricular contractility. The percentage of increase in the flow velocity-time integral of early diastolic filling during dobutamine infusion tended to correlate with the increase in stroke volume (r=0.67,p<0.05) and with the decrease in end-systolic wall stress (r=−0.61,p<0.05). Our results suggest that low-dose dobutamine increases left ventricular relaxation with enhanced systolic function. The observed decreased end-systolic wall stress might have caused enhanced relaxation characteristics with dobutamine.

Role of age on transmitral flow velocity patterns in assessing left ventricular diastolic function in normal infants and children

This study demonstrated that both peak E and flow velocity integral of early diastole increased to reach the older childrens values by 36 months of age and leveled off thereafter, whereas both peak A and flow velocity integral of atrial contraction had little change. These results suggest that age-related changes in E wave reflect the maturational or developmental alterations in LV diastolic properties, especially in the relaxation process.

In Situ Morphology of the Ductus Venosus and Related Vessels in the Fetal and Neonatal Rat

ABSTRACT: In situ cross-sectional morphology of the ductus venosus and related vessels was studied after rapid whole-body freezing of the fetal and neonatal rat. In the fetus, the ductus venosus was open widely, connecting the umbilical sinus and the inferior vena cava. The diameter of the ductus venosus was 50% of the diameter of the umbilical sinus. The ductus venous joined the left dorsal side of the inferior vena cava. A thin, short, membrane-like edge was present at the inner junction of the ductus venosus and the inferior vena cava, presumably effecting laminar flow of the ductus venosus blood to the left side of the thoracic inferior vena cava. A very prominent eustachian valve was present at the junction of the inferior vena cava and the right atrium, presumably directing its flow to the opening of the foramen ovale. After birth, the ductus venosus narrowed rapidly and closed completely in 2 d. The closing ductus venosus was tubular, with the cranial end slightly wider than the caudal portion. Localized constriction was not present. These observations showed the structural substrate for preferential flow from the ductus venosus to the foramen ovale and left atrium in the fetus and did not support localized sphincter mechanism in postnatal closure of the ductus venosus.

Hypoplasia of the Lung and Heart in Fetal Rats with Diaphragmatic Hernia

We studied 11 fetal rats with normal heart and diaphragmatic hernia induced by administration of bis-diamine (200 mg) on the 9th and 10th day of pregnancy. After rapid whole-body freezing on the 21st day, the fetuses were studied by means of serial cross-sectional photographs of the frozen thorax. In the fetuses with hernia, the left half of the diaphragm was completely absent, and the liver and stomach were in the left hemithorax. The lung and heart were hypoplastic in fetal diaphragmatic hernia. Cardiac volume reduction involved all four chambers and was more prominent in the left atrium and ventricles. The great vessels were also smaller.

Effect of aging from infancy to childhood on flow velocity patterns of pulmonary vein by Doppler echocardiography

This study demonstrated the age-related changes in pulmonary venous flow velocities during 36 months of life. These results suggest that age-related changes in the D and S wave reflect the maturational or developmental alterations in both LV and left atrial diastolic properties, especially during the relaxation process.

In situ morphology of the foramen ovale in the fetal and neonatal rat.

ABSTRACT: In situ cross-sectional morphology of the foramen ovale was studied after rapid whole-body freezing of the fetal and neonatal rat. In the fetus, the foramen ovale was open widely toward the left atrium with a thin, short primum septum. The opening area of the foramen ovale was 40% of the cross-section of the thoracic inferior vena cava, and the ratio of the long diameter to the short diameter was 2 to 1. After birth, the primum septum became longer, thicker, and straighter, with less leftward bowing. The opening of the foramen ovale diminished in the first 2 d and closed completely 3 d after birth. Postnatal thickening of the primum septum was very remarkable, increasing by 400% in the first 2 d, while only minimal change was noticed in the right and the left atrial walls. The length of the primum septum was short and was only 90% of the diameter of the fossa ovalis in the fetus. It increased and reached 97% and 111% of the diameter of the fossa ovalis 1 and 2 d after birth, respectively. The septum secundum also grew rapidly after birth, and its length and width increased by 40% and 29% after 1 and 2 d, respectively. These observations indicate a sudden, explosive growth of the atrial septum in the early neonatal period in the rat.

An infant with hypereosinophilic syndrome and heart failure markedly responded to prednisolone: serial changes of left ventricular wall thickening and left ventricular diastolic dysfunction observed by echocardiography

SummaryWe encountered an infant with congestive heart failure due to idiopathic hypereosinophilic syndrome. The patient showed marked thickening of the left ventricular wall and left ventricular diastolic dysfunction, both of which, shortly after prednisolone therapy, markedly improved together with improvement of the congestive heart failure and hypereosinophilia. Observation of pulmonary venous flow patterns detected by pulsed Doppler echocardiography may be useful for evaluation of left ventricular diastolic function.

Perinatal adaptation of the cardiovascular system

The perinatal changes in the cardiovascular system were studied in fetal rats. The changes in the cardiovascular system occurred earlier than in humans. The ductus arteriosus closes in the rat in one and a half hours.

Changes in Pulmonary Venous Flow Patterns in Patients with Ventricular Septal Defect

AbstractWe studied pulmonary venous (PV) flow patterns using Doppler echocardiography in 26 patients with ventricular septal defect less than 3 years of age. Fifteen patients had moderate or severe symptoms, and the remaining 11 had no significant symptoms. Peak velocity of PV diastolic flow and flow velocity integral of PV diastolic flow in the symptomatic patients were significantly larger than those in either asymptomatic patients or the normal controls. The ratio of PV diastolic flow velocity to PV systolic flow velocity and the ratio of flow velocity integral of PV diastolic flow to that of PV systolic flow in the symptomatic patients were significantly larger than those in either asymptomatic patients or the normal controls. The ratio of PV diastolic flow velocity to PV systolic flow velocity as well as the ratio of flow velocity integral of PV diastolic flow to that of PV systolic flow correlated with V wave in left atrial or pulmonary capillary wedge pressure and indexes of left ventricular mass and left atrial volume. We conclude that the abnormal pulmonary venous flow patterns in ventricular septal defect might be associated with large left-to-right shunting and left atrial pressure V wave.