Noninvasive assessment of myocardial mechanics of the left ventricle in rabbits using velocity vector imaging.

BACKGROUND: Our study aimed to investigate the feasibility of velocity vector imaging (VVI) to analyze left ventricular (LV) myocardial mechanics in rabbits at basal state. MATERIAL AND METHODS: The animals used in this study were 30 New Zealand white rabbits. All rabbits underwent routine echocardiography under VVI-mode at basal state. The 2-dimensional (2-D) echocardiography images acquired included parasternal left long-axis views and short-axis views at the level of LV mitral valve, papillary muscles, and apex. Images were analyzed by VVI software. RESULTS: At basal state, longitudinal LV velocity decreased from the basal to the apical segment (P<0.05). In the short axis direction, the highest peak myocardial velocity was found between the anterior septum and anterior wall for each segment at the same level; the peak strains and strain rates (SR) were the highest in the anterior and lateral wall compared to other segments (all P<0.05). During systole, LV base rotated in a clockwise direction and LV apex rotated in a counter-clockwise direction, while during diastole, both LV base and apex rotated in the direction opposite to systole. The rotation angle, rotation velocity and unwinding velocity in the apical segment were greater than the basal segment (P<0.05). CONCLUSIONS: VVI is a reliable tool for evaluating LV myocardial mechanics in rabbits at basal state, and the LV long-axis short-axis and torsional motions reflect the normal regular patterns. Our study lays the foundation for future experimental approaches in rabbit models and for other applications related to the study of human myocardial mechanics.

Four-dimensional echocardiography with B-flow imaging and spatiotemporal image correlation in the assessment of congenital heart defects.

OBJECTIVE: The objective of the present study was to evaluate the role of four-dimensional ultrasound with B-flow imaging and spatiotemporal image correlation (STIC) in the detection of congenital heart defects. METHODS: Automated longitudinal and transverse sweeping of the fetal chest was utilized to obtain the volume datasets of the heart. Among the fetuses recruited in the study, 20 were normal and 13 were fetuses with congenital heart anomalies. Reconstructed images of abnormal hearts were compared with those of normal fetuses. RESULTS: Of the 20 normal fetuses, all extracardiac vessels such as aorta, pulmonary artery, ductus artery, inferior vena cava, and ductus venosus could be detected on reconstructed images of 16 fetuses. In five normal cases, a four-dimensional image was recorded to allow simultaneous visualization of all four pulmonary veins. In the 13 fetuses with cardiac anomalies, four-dimensional sonography with B-flow imaging and STIC detected the 'digital casts' of the outflow tracts, great arteries, and veins draining into the heart. These results demonstrate spatial relationship among these structures which provide important anatomical information. CONCLUSIONS: The use of four-dimensional ultrasound examination with B-flow imaging and STIC is a very useful technique in identifying anatomical features of different congenital cardiac anomalies.

Evaluation of regional left ventricular longitudinal function in 151 normal fetuses using velocity vector imaging.

OBJECTIVE: The purpose of this study was to investigate the clinical value of velocity vector imaging (VVI) in the assessment of normal fetal regional myocardial performance and to establish a normative data set for normal Chinese fetuses. METHODS: One hundred and fifty-one healthy Chinese fetuses were divided into five groups according to their gestational age. Digital dynamic four-chamber views were collected and analyzed offline. The regional tissue velocity, strain, and strain rate of the interventricular septum and left lateral wall were measured in systole and diastole. RESULTS: Normal systolic and diastolic values for tissue velocity, strain, and strain rate were established. Tissue velocity decreased gradually from the basal segment to the apical segment (P < 0.01), whereas the strain and strain rate were stable among all segments in every group (P > 0.05). Tissue velocity was dependent on gestational age (P < 0.05), whereas strain and strain rate were stable throughout gestation (P > 0.05). CONCLUSION: VVI is a novel noninvasive tool for quantitative assessment of regional systolic and diastolic function of the fetal heart. Fetal myocardial velocity, strain, and strain rate measurements can be measured easily and reproducibly. This technique is useful for evaluating cardiac function.

Prenatal diagnosis of type 1 tracheal agenesis without tracheoesophageal fistula.

Tracheal agenesis is a rare and uniformly lethal congenital malformation. We recently had the opportunity to diagnose prenatally a case of type I tracheal agenesis without fistula in a 22-week-old fetus, in which the hyperechogenicity of the enlarged lungs was associated with ascites, and tracheal dilatation in the lower half. We report the ultrasonographic and autopsy findings and review the literature on this rare condition to contribute to the understanding of type 1 tracheal agenesis without tracheoesophageal fistula.

Assessment of regional myocardial function in patients with dilated cardiomyopathy by velocity vector imaging.

OBJECTIVE: To assess the left ventricular (LV) longitudinal systolic and diastolic function in patients with dilated cardiomyopathy (DCM) by syngo Velocity Vector Imaging (VVI). METHODS: Digital dynamic images of 30 DCM patients and 30 healthy subjects were collected; then the longitudinal velocity, strain, and strain rate were measured in systolic early and late diastolic periods, and the time to peak systolic velocity, strain, and strain rate were measured and recorded. The parameters of the two groups were compared. RESULTS: All of the parameters of the DCM were significantly lower than those of the normal group (P < 0.05-0.01), except that the parameter of late diastolic strain was not different between the two groups (P > 0.05). CONCLUSIONS: VVI is a novel noninvasive tool to assess quantitatively and objectively LV regional systolic and diastolic function in patients with DCM; it provides another useful modality for evaluating cardiac function.