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.

TACRD and VACTERL associations in a fetus: case report and review of the literature.

Tracheal agenesis is a rare and potentially lethal congenital anomaly. The incidence is less than 1/50,000, with a male:female ratio of 2:1. We report the case of a male fetus with complete agenesis of the trachea and a tracheoesophageal fistula arising from the esophagus that connected through the carina, as well as several abnormalities (congenital cardiac abnormalities, duodenal atresia, vertebral defects, anal atresia, renal defects, limb defects, and diaphragmatic hernia). To our knowledge, few cases of infants with VACTERL or TACRD association have been reported to date. Here, we report a new case of a fetus that showed the full range of VACTERL and TACRD associations.

Assessment of regional right ventricular longitudinal functions in fetus using velocity vector imaging technology.

OBJECTIVES: The velocity vector imaging (VVI) technique is useful to assess regional myocardial mechanics. The aim of this study was to evaluate the usefulness of this technology in assessing regional right ventricular longitudinal functions in the fetus and to establish a nomogram of the right ventricle (RV). METHODS: We studied 170 healthy fetuses that were divided into five groups based on gestational age. Dynamic digital images of four chambers were collected and analyzed off-line. The longitudinal VVI parameters were calculated in the right free wall and ventricular septum, respectively. RESULTS: A total of 151 out of 170 fetuses (89%) were successfully analyzed using VVI, with good inter- and intra-observer agreements. Normal values for velocity, strain, and strain rate were established. The tissue velocity gradually decreased from basal to apical segment (P < 0.05), whereas strain and strain rate remained stable. The tissue velocity increased with gestational age (P < 0.05), whereas strain and strain rate were stable (P > 0.05). CONCLUSION: Fetal myocardial velocity, strain, and strain rate measurements are easy to obtain and are reproducible. From mid-to-late gestation, the longitudinal tissue velocity of the RV increases with gestational age, whereas strain and strain rate remain stable. These results indicate that myocardial contractility is established in mid-gestation and remains constant throughout gestation.

Differences in left ventricular twist related to age: speckle tracking echocardiographic data for healthy volunteers from neonate to age 70 years.

OBJECTIVE: To determine normal left ventricular (LV) twist characteristics in different age groups and assess changes between neonates and the elderly. METHODS: Short-axis left ventricle images at basal and apical levels were acquired in 274 healthy volunteers (aged 15 days to 72 years) by two-dimensional echocardiography, and were analyzed off-line using Speckle tracking echocardiography (STE) software to obtain LV twist measurements. The peak apical rotation (PAr), peak basal rotation (PBr), peak LV twist (Ptw), peak LV twist normalized by LV length (PtwN), peak untwisting velocity (PutwV), and isovolumic untwisting% (Iutw%) were measured. RESULTS: LV twist values vary with age. Ptw was higher in older volunteers. PtwN varied inconsistently with age. PutwV and Iutw% were lower in the young and old with a peak in mid-age ranges. CONCLUSIONS: STE is an effective noninvasive method to assess LV twist. Age-related differences in LV twist may reflect maturation and adaptive modulation of LV torsional biomechanics from neonate to the elderly.

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.

Clinical applications of N-terminal pro B-type natriuretic peptide in heart failure and other cardiovascular diseases.

N-terminal fragment of pro B-type natriuretic peptide (NT-proBNP) has emerged as an important adjunct in the management of heart failure (HF) and other cardiovascular diseases. NT-proBNP is a 76-amino acid peptide created during cleavage of the precursor molecule, Pro B-type natriuretic peptide (ProBNP). NT-proBNP is of significant diagnostic value in patients presenting with possible HF and is an important prognostic factor in this condition and other cardiovascular diseases. Ongoing research supports the potential value of this biomarker in non-cardiovascular disease. This review will describe clinical applications of NT-proBNP in HF and a broad range of other conditions.

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.

HDL slowing down endothelial progenitor cells senescence: a novel anti-atherogenic property of HDL.

Numerical and functional impairment of circulating endothelial progenitor cells (EPCs) is thought to contribute to endothelial dysfunction and the associated increase in cardiovascular risk. Increased EPCs number and activity are associated with the inhibition of EPCs senescence, which involved activation of telomerase. Telomerase activity can be regulated by phosphatidylinositol-3-kinase/Akt (PI3K/Akt) signaling pathway which also modulates the activity of endothelial nitric oxide synthase (eNOS). Increased oxidative stress induces telomerase inactivity whereas nitric oxide (NO) can reduce oxidative stress, thus activates telomerase. Plasma high-density lipoprotein (HDL) cholesterol levels have an inverse correlation with incidence of ischemic heart disease as well as other atherosclerosis-related ischemic conditions. However, the exact mechanism by which HDL prevents ischemic disease is not fully understood. HDL not only increases NO by activating eNOS through PI3K/Akt signaling pathway, but also directly stimulates EPCs differentiation via PI3K/Akt pathway. Moreover HDL can increase circulating EPCs number and enhances ischemia-induced angiogenesis. On the basis of recent findings, this manuscript proposed a new hypothesis that HDL could against atherosclerotic cardiovascular disease partially through slowing down EPCs senescence by increasing NO and promoting telomerase activity via PI3K/Akt signaling pathway.

Remnant like particles may induce atherosclerosis via accelerating endothelial progenitor cells senescence.

Remnant like particles (RLPs) are closely associated with coronary heart disease, whereas the underlying mechanisms are complex and have not been fully elucidated. Studies show that maintenance of endothelial cells layer is essential for normal function of vessel. Endothelial progenitor cells (EPCs) were shown to incorporate into sites of neovascularization and home to sites of endothelial denudation, thus provide an endogenous repair mechanism. Risk factors of coronary heart disease can impair EPCs repairing function by inducing EPCs senescence. EPCs senescence is associated with telomerase inactivation, which is regulated via phosphatidylinositol-3-kinase/Akt kinase (PI3K/Akt) signaling pathway. RLPs are triglyceride rich lipoproteins reflecting chylomicron remnants and very-low-density lipoprotein remnants. RLPs can impair endothelial function via inhibiting endothelial NO synthase (eNOS) activity and nitric oxide (NO) production by inducing intracellular oxidant levels. However, there is no research about effect of RLPs on EPCs. Evidence shows that RLPs can induce focal adhesion kinase (FAK) activation in monocytic U937 cells. Therefore, it can be hypothesized that RLPs could inhibit eNOS and telomerase activities, thus induce atherosclerosis by promoting EPCs senescence via FAK and its downstream PI3K/Akt pathway through an oxidative mechanism.