Masamichi Tamura

Comparison of the right ventricular Tei index by tissue Doppler imaging to that obtained by pulsed Doppler in children without heart disease.

This study demonstrated that the TDI-Tei index correlates well with the Tei index determined by pulsed Doppler, and thus represents a simple method of assessing RV myocardial performance. Moreover, the TDI-Tei index has the advantage of simultaneous recording of systolic and diastolic velocity patterns, suggesting that the TDI-Tei index is a feasible approach to assess global RV function in children.

Doppler Echocardiographic Evaluation of Left Ventricular Output and Left Ventricular Diastolic Filling Changes in the First Day of Life

ABSTRACT: The aim of this study was to evaluate the changes in Doppler transmitral flow patterns during the 1st d of life. Doppler echocardiography of the ascending aorta and mitral valve was performed serially in 20 normal neonates at 2, 12, and 24 h of age. A computer-interfaced digitizer pad was used to measure the following: ascending aorta flow velocity-time integral, total diastolic filling flow velocity-time integral, flow velocity-time integral of early diastolic filling, and flow velocity-time integral of atrial contraction. The inner diameter of the ductus arteriosus was 4.2 ± 0.6 mm at 2 h of age, 2.3 ± 0.5 mm at 12 h of age, and had closed in 17 of 20 neonates (85%) by 24 h of age. The ascending aorta flow velocity-time integral and total diastolic filling flow velocity-time integral, which were high at 2 h of age, decreased significantly at 12 h of age [12.2 ± 2.1 cm versus 9.6 ± 1.7 cm (p < 0.001) and 8.0 ± 1.1 versus 7.1 ± 1.4 (p < 0.01), respectively] but remained constant thereafter. Although no significant changes in flow velocity-time integral of atrial contraction and peak velocity of atrial contraction were noted during the first 24 h of birth, the flow velocity-time integral of early diastolic filling and peak velocity of early diastolic filling that were high at 2 h of age were reduced significantly at 12 h of age [5.0 ± 0.9 cm versus 4.1 ± 1.1 cm (p < 0.005) and 60.9 ± 9.0 cm/s versus 50.3 ± 9.0 cm/s (p < 0.001), respectively], resulting in significant reductions in the ratio of flow velocity-time integral of early diastolic filling/flow velocity-time integral of atrial contraction and the ratio of peak velocity of early diastolic filling/peak velocity of atrial contraction at 12 h of age. The size of the ductus arteriosus was found to be correlated with the peak velocity of early diastolic filling (r = 0.42, p < 0.05). Our results clearly demonstrate that the pattern of early diastolic filling was dependent on preload, whereas that of late diastolic filling was independent of preload in the early neonatal period.

Tei Index Determined by Tissue Doppler Imaging in Patients with Pulmonary Regurgitation After Repair of Tetralogy of Fallot

The myocardial performance index (Tei index) determined by the pulsed Doppler method is a simple and noninvasive measurement for assessing global right ventricular (RV) function. This index can also be obtained by tissue Doppler imaging (TDI). The effects of significant pulmonary regurgitation (PR) on the determination of the Tei index by these two methods have not been investigated. We examined 15 patients (6.3 ± 2.2 years) with significant PR after repair of tetralogy of Fallot (TOF) and 24 age-matched healthy children. Myocardial wall motion velocities at the tricuspid annulus were assessed during systole (Sa), early diastole (Ea), and late diastole (Aa) from a four-chamber view. Pulsed Doppler–Tei index and TDI–Tei index were measured as reported previously. The Tei index obtained by the pulsed Doppler method in TOF patients did not differ from that in normal children (0.30 ± 0. 12 vs 0.32 ± 0.07, p = not significant). TDI showed that TOF patients had significantly decreased Ea, Aa, and Sa velocities compared to those of normal children. Both isovolumic contraction time and isovolumic relaxation time in TOF patients were significantly longer than those in normal children (88 ± 18 vs 62 ± 23 msec and 46 ± 11 vs 21 ± 12 msec, respectively; p < 0.0001), although the duration of Sa did not differ between the two groups. Consequently, the Tei index as measured by TDI was significantly greater in TOF patients than in normal children (0.48 ± 0.07 vs 0.30 ± 0.07, p < 0.0001). The Tei index measured by the pulsed Doppler method is limited in its ability to assess RV function in patients with significant PR. However, the Tei index determined by TDI is a sensitive indicator of RV function in these patients, and it appears to be a promising new means of assessing global RV function in patients with significant PR.

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.

A comparison of tissue doppler imaging and velocities of transmitral flow in children with elevated left ventricular preload

Compared with transmitral velocities of flow, myocardial wall velocities obtained by tissue Doppler imaging are less influenced by left atrial pressure. The data supporting this assumption, however, are limited in patients with congenital cardiac disease. The aim of this study was to compare the effects of left ventricular preload on transmitral inflow and velocities assessed by tissue Doppler imaging. Tissue Doppler imaging, and conventional Doppler echocardiography with simultaneous invasive hemodynamic studies, were performed in 33 patients with a simple ventricular septal defect or patency of the arterial duct. Transmitral velocities (E, A) and mitral annular velocities (Ea, Aa) were measured, permitting calculation of the ratio of E to Ea. The ratio of pulmonary to systemic flows, and mean left atrial pressure, were also measured. In 10 of 33 patients, echocardiographic and hemodynamic studies were performed 4 to 5 months after surgery. The E and A values in the patients were greater than those in the controls (p < 0.01). In contrast, neither Ea nor Aa differed between the two group. The ratio of E to Ea in the patients increased significantly compared with that in the controls (8.9+/-2.1 vs 7.3+/-1.3, p < 0.01). The E value was directly related to mean left atrial pressure and the ratio of pulmonary to systemic flows. The velocities measured by Tissue Doppler imaging, however, had no significant relationship to either of these measurements. The ratio of E to Ea correlated well with mean left atrial pressure (r = 0.75, p < 0.01). In 10 post-operative patients, the values for E and A decreased from 119+/-14 to 89+/-10 cm/sec (p < 0.01) and from 91+/-22 to 61+/-9 cm/sec (p < 0.01), respectively. No significant changes were noted in the values of Ea and Aa. The ratio of E to Ea, and mean left atrial pressure, decreased from 10.3+/-1.9 to 8.2+/-1.5 (p < 0.01) and from 11.0+/-1.8 to 7.4+/-1.0 mmHg (p < 0.01), respectively. The percentage change in left atrial pressure correlated with the percent change in the ratio of E to Ea (r = 0.64, p < 0.05). The present study showed that the velocities obtained with tissue Doppler imaging are less dependent on mean left atrial pressure in children with elevated left ventricular preload caused by a left-to-right shunt.

Clinical Features and Management of Isolated Cleft Mitral Valve in Childhood

OBJECTIVES We reviewed an institutional experience of isolated cleft mitral valve (ICMV), its clinical features, and management in a pediatric population. BACKGROUND As ICMV is relatively uncommon, earlier reports highlighted its anatomical and echocardiographic features. Few studies have collated their clinical features with their outcome. METHODS All patients with ICMV were retrospectively reviewed. Patients who were considered to have an atrioventricular septal defect or variant were excluded. RESULTS Twenty patients (9 male, 11 female) were diagnosed with ICMV. Seven patients had associated cardiac lesions. The median age of diagnosis was 5.2 years (range 0.4 to 13.6 years). Echocardiography aided by color Doppler demonstrated the ICMV in all patients. However, an incomplete diagnosis was made in 4 of 20 patients before surgery. The severity of the mitral regurgitation (MR) at presentation was mild in 11, moderate in 8, and severe in 1 patient. In the 13 patients without associated cardiac lesions, 5 underwent mitral valve (MV) repair at median age of 5.2 years (range 1.2 to 7.7 years) for moderate to severe MR, 4 being symptomatic. The severity of the MR in seven of the eight unoperated patients has remained unchanged over the follow-up period (median 8.3 years, range 0.7 to 14.4 years). In total, 10 patients underwent MV repair (median 6.4, range 0.4 to 13.8 years). No patient required MV replacement. None of the 10 patients had more than mild MR over the follow-up period (median 0.6, range 0.2 to 11.0 years). CONCLUSIONS Now readily diagnosable by echocardiography, ICMV is a correctable cause of MR with a good outcome. Surgery is indicated in those patients with moderate to severe MR and probably should be done early following diagnosis.

Changes in left ventricular volume and systolic function before and after the closure of ductus arteriosus in full-term infants

Using echocardiographic techniques, the change in left ventricular (LV) volume and its effect on systolic function were studied before and after the closure of ductus arteriosus in 18 full-term infants. Examinations were performed twice in each infant, within 6 h after birth and on day 5, and the patency of the ductus with left-to-right shunt was confirmed at the first examination by Doppler echocardiography. A biplane Simpsons rule method was used for volume measurements. The LV end-diastolic volume, stroke volume, and cardiac output were more than 1.3-fold before the ductal closure, and the ejection fraction showed the similar change. However, the mean normalized systolic ejection rate, an index of contractility, and heart rate showed no significant difference. The Frank-Starling curve was obtained from the relationship between the LV end-diastolic and stroke volumes, and the LV performance was operated at a higher level on that curve when the ductus was open. Our data indicated that LV cardiac output was significantly higher during the patency of the ductus arteriosus and that this high cardiac performance might depend more on the Frank-Starling response to the volume load through the ductus arteriosus than on the increase of LV contractility and heart rate.

Coronary Blood Flow Assessed by Transthoracic Echocardiography in Neonates

Abstract. Coronary flow measurement has provided useful clinical and physiologic information. However, there is little information about values for coronary flow in normal neonates, much less neonates with congenital heart disease. The aim of this study was to assess coronary blood flow in normal neonates and to compare the results with those in infants with ventricular septal defect. The study groups consisted of 12 normal neonates and 9 infants with simple ventricular septal defect associated with pulmonary hypertension. Left ventricular dimension, left ventricular mass, and the diameter of the coronary vessel were measured by standard M-mode and two-dimensional echocardiography. Peak flow velocities, flow velocity integrals, and flow volumes in the left anterior descending and circumflex coronary arteries were measured. The flow signals from the left anterior descending and circumflex coronary arteries were recorded in 84% (10/12) and 17% (2/12), respectively, in the normal neonates and 78% (7/9) and 11% (1/9), respectively, in the patients. The left ventricular end diastolic diameter and mass were significantly lower in normal infants than in the infants with ventricular septal defect (1.56 ± 0.11 vs 1.84 ± 0.09 cm and 5.4 ± 1.6 vs 8.8 ± 0.8 g, respectively, p < 0.01). The mean peak diastolic velocity and the flow velocity time integral in the left anterior descending coronary artery were significantly lower in the normal neonates than in the patients (15 ± 4 vs 28 ± 6 cm/sec and 2.3 ± 0.6 vs 5.9 ± 1.5 cm, respectively, p < 0.01). The coronary flow volume was significantly lower in the normal neonates than in the patients (3.1 ± 1.4 vs 7.9 ± 4.7 ml/min, p < 0.05). However, the flow volume of the left anterior descending coronary artery/left ventricular mass did not show any significant difference between the two groups. Our study demonstrated in neonates that it is feasible to detect noninvasively and to evaluate the flow of the left anterior descending coronary artery under physiologic conditions and abnormal hemodynamic situations. Increased flow volume in the left anterior descending coronary artery in patients with ventricular septal defect may be a compensated mechanism for the increase in oxygen demand of hypertrophic myocardium of the left ventricle.