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pulsed wave Doppler ultrasound pulsed Doppler ultrasound [keywords]
- [Tissue Doppler imaging in the evaluation of cardiac function in fetuses with intrauterine growth retardation]. [English Abstract, Journal Article]
- Zhong Nan Da Xue Xue Bao Yi Xue Ban 2014 Sep; 39(9):935-8.
To evaluate the cardiac function of fetuses with intrauterine growth retardation (IUGR) by using tissue Doppler imaging (TDI).Peak velocity in early (E) and late (A) diastole were measured by pulsed-wave Doppler, and the peak annular velocities in systole (S'), early (E') and late (A') diastole were measured by TDI. Isovolumetric contraction time (ICT), ejection time (ET), isovolumetric relaxation time (IRT) were recorded. The ratios E/A, E'/A', E/E', E/(E'× S') and myocardial performance index (MPI) were calculated.Compared with the control group, E', A', S' and E'/A' were obviously lower (P<0.05) while E/E', E/(E'× S') and MPI were obviously higher (P<0.05) in the IUGR group; although E, A and E/A were slight lower in the IUGR group, the change was not significant (P>0.05).Both diastolic and systolic heart function were jeopardized in IUGR fetuses.
- Hemodynamics and ventricular function in a zebrafish model of injury and repair. [Journal Article]
- Zebrafish 2014 Oct; 11(5):447-54.
Abstract Myocardial infarction results in scar tissue and irreversible loss of ventricular function. Unlike humans, zebrafish has the capacity to remove scar tissue after injury. To assess ventricular function during repair, we synchronized microelectrocardiogram (μECG) signals with a high-frequency ultrasound pulsed-wave (PW) Doppler to interrogate cardiac hemodynamics. μECG signals allowed for identification of PW Doppler signals for passive (early [E]-wave velocity) and active ventricular filling (atrial [A]-wave velocity) during diastole. The A wave (9.0±1.2 cm·s(-1)) is greater than the E wave (1.1±0.4 cm·s(-1)), resulting in an E/A ratio <1 (0.12±0.05, n=6). In response to cryocauterization to the ventricular epicardium, the E-wave velocity increased, accompanied by a rise in the E/A ratio at 3 days postcryocauterization (dpc) (0.55±0.13, n=6, p<0.001 vs. sham). The E waves normalize toward the baseline, along with a reduction in the E/A ratio at 35 dpc (0.36±0.06, n=6, p<0.001 vs. sham) and 65 dpc (0.2±0.16, n=6, p<0.001 vs. sham). In zebrafish, E/A<1 at baseline is observed, suggesting the distinct two-chamber system in which the pressure gradient across the atrioventricular valve is higher compared with the ventriculobulbar valve. The initial rise and subsequent normalization of E/A ratios support recovery in the ventricular diastolic function.
- Low cardiac output as physiological phenomenon in hibernating, free-ranging scandinavian brown bears (Ursus arctos) - an observational study. [JOURNAL ARTICLE]
- Cardiovasc Ultrasound 2014 Sep 16; 12(1):36.
Despite 5-7 months of physical inactivity during hibernation, brown bears (Ursus arctos) are able to cope with physiological conditions that would be detrimental to humans. During hibernation, the tissue metabolic demands fall to 25% of the active state. Our objective was to assess cardiac function associated with metabolic depression in the hibernating vs. active states in free-ranging Scandinavian brown bears.We performed echocardiography on seven free-ranging brown bears in Dalarna, Sweden, anesthetized with medetomidine-zolazepam-tiletamine-ketamine during winter hibernation in February 2013 and with medetomidine-zolazepam-tiletamine during active state in June 2013. We measured cardiac output noninvasively using estimates of hemodynamics obtained by pulsed wave Doppler echocardiography and 2D imaging. Comparisons were made using paired T-tests.During hibernation, all hemodynamic indices were significantly decreased (hibernating vs. active state): mean heart rate was 26.0 (standard deviation (SD): 5.6) beats per min vs. 75.0 (SD: 17.1) per min (P = 0.002), mean stroke volume 32.3 (SD: 5.2) ml vs. 47.1 (SD: 7.9) ml (P = 0.008), mean cardiac output 0.86 (SD: 0.31) l/min vs. 3.54 (SD: 1.04) l/min (P = 0.003), and mean cardiac index 0.63 (SD: 0.21) l/min/kg vs. 2.45 (SD: 0.52) l/min/ m2 (P < 0.001). Spontaneous echo contrast was present in all cardiac chambers in all seven bears during hibernation, despite the absence of atrial arrhythmias and valvular disease.Free-ranging brown bears demonstrate hemodynamics comparable to humans during active state, whereas during hibernation, we documented extremely low-flow hemodynamics. Understanding these physiological changes in bears may help to gain insight into the mechanisms of cardiogenic shock and heart failure in humans.
- A review of Doppler ultrasound quality assurance protocols and test devices. [JOURNAL ARTICLE]
- Phys Med 2014 Sep 8.
In this paper, an overview of Doppler ultrasound quality assurance (QA) testing will be presented in three sections. The first section will review the different Doppler ultrasound parameters recommended by professional bodies for use in QA protocols. The second section will include an evaluation and critique of the main test devices used to assess Doppler performance, while the final section of this paper will discuss which of the wide range of test devices have been found to be most suitable for inclusion in Doppler QA programmes. Pulsed Wave Spectral Doppler, Colour Doppler Imaging QA test protocols have been recommended over the years by various professional bodies, including the UK's Institute of Physics and Engineering in Medicine (IPEM), the American Institute for Ultrasound in Medicine (AIUM), and the International Electrotechnical Commission (IEC). However, despite the existence of such recommended test protocols, very few commercial or research test devices exist which can measure the full range of both PW Doppler ultrasound and colour Doppler imaging performance parameters, particularly quality control measurements such as: (i) Doppler sensitivity (ii) colour Doppler spatial resolution (iii) colour Doppler temporal resolution (iv) colour Doppler velocity resolution (v) clutter filter performance and (vi) tissue movement artefact suppression. In this review, the merits of the various commercial and research test devices will be considered and a summary of results obtained from published studies which have made use of some of these Doppler test devices, such as the flow, string, rotating and belt phantom, will be presented.
- 3D ultrafast ultrasound imaging in vivo. [JOURNAL ARTICLE]
- Phys Med Biol 2014 Sep 10; 59(19):L1-L13.
Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in 3D based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32 × 32 matrix-array probe. Its ability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3D Shear-Wave Imaging, 3D Ultrafast Doppler Imaging, and, finally, 3D Ultrafast combined Tissue and Flow Doppler Imaging. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3D Ultrafast Doppler was used to obtain 3D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, at thousands of volumes per second, the complex 3D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, as well as the 3D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3D Ultrafast Ultrasound Imaging for the 3D mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra-and inter-observer variability.
- Transplantation of pulmonary valve using a mouse model of heterotopic heart transplantation. [Journal Article, Research Support, N.I.H., Extramural, Video-Audio Media]
- J Vis Exp 2014; (89)
Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed results. However, the cellular and molecular mechanisms of the neotissue development, valve thickening, and stenosis development are not researched extensively. To answer the above questions, we developed a murine heterotopic heart valve transplantation model. A heart valve was harvested from a valve donor mouse and transplanted to a heart donor mouse. The heart with a new valve was transplanted heterotopically to a recipient mouse. The transplanted heart showed its own heartbeat, independent of the recipient's heartbeat. The blood flow was quantified using a high frequency ultrasound system with a pulsed wave Doppler. The flow through the implanted pulmonary valve showed forward flow with minimal regurgitation and the peak flow was close to 100 mm/sec. This murine model of heart valve transplantation is highly versatile, so it can be modified and adapted to provide different hemodynamic environments and/or can be used with various transgenic mice to study neotissue development in a tissue engineered heart valve.
- Use of fetal echocardiography for characterization of fetal cardiac structure in women with normal pregnancies and gestational diabetes mellitus. [Journal Article]
- J Ultrasound Med 2014 Aug; 33(8):1365-9.
To assess fetal cardiac structure and function and to evaluate the efficacy of routine fetal echocardiography for detection of fetal cardiac abnormalities in women with normal pregnancies and those with gestational diabetes mellitus.In this prospective study, we studied fetal cardiac structure and function in 294 uncomplicated singleton pregnancies and 302 pregnancies complicated by gestational diabetes. Fetal echocardiography (2-dimensional sonography and pulsed wave Doppler imaging) was used to assess functional parameters and to detect any cardiac structural abnormality. Data from clinical and echocardiographic evaluations of neonates at birth and 3 months were obtained to confirm the antenatal findings.The mean maternal age ± SD was 28.9 ± 5.0 years in the diabetes group and was comparable to that of women with normal pregnancies. The mean hemoglobin A1c value was 6.3%, and the mean body mass index was 28.0 kg/m(2). The systolic function as assessed by the ejection fraction increased significantly in the diabetes group compared to the normal pregnancy group independent of glycemic control (P < .001). The pulsed wave parameters (early diastolic peak flow velocity and early-to-late diastolic peak flow velocity ratio) were significantly different between the groups (P < .001). The interventricular septum and fetal ventricular wall thicknesses were significantly increased in the presence of gestational diabetes (P < .001). No major fetal cardiac structural anomaly was detected in either group. On follow-up after delivery, all neonates were assessed clinically and by transthoracic echocardiography to rule out congenital defects.In our study, significant increases in the interventricular septum and ventricular wall thicknesses were detected in the presence of gestational diabetes mellitus. Interestingly, none of the neonates of pregnant women with gestational diabetes were found to have echocardiographic evidence of congenital heart disease.
- Age- and gender-specific changes of tricuspid annular motion velocities in normal hearts. [JOURNAL ARTICLE]
- J Cardiol 2014 Jul 22.
Mitral annular motion (MAM) and tricuspid annular motion (TAM) velocities obtained by pulsed tissue Doppler echocardiography have been used to evaluate left ventricular (LV) and right ventricular (RV) functions. Although TAM velocity has been clinically applied for evaluating various cardiac diseases, the effects of age and gender remain unclear. Therefore, we aimed to determine the effects of age and gender on TAM velocity in normal hearts.We randomly selected 265 subjects (mean age, 59 years; range, 20-89 years) without abnormal clinical, electrocardiographic, and echocardiographic findings from a pool of subjects who had undergone transthoracic echocardiography. They were classified into four age groups: 20-39, 40-59, 60-79, and >80 years. Pulsed wave Doppler was applied to obtain MAM velocity of the lateral side and TAM velocity of the RV free wall side. The peak systolic (s'), early diastolic (e'), and atrial systolic (a') velocities of MAM and TAM were measured in all subjects.While MAM-s' (r=-0.267, p<0.001) correlated with age, TAM-s' did not (p=0.755). TAM-s' in any age groups had no significant gender differences. TAM-e' (r=-0.447, p<0.001) and MAM-e' (r=-0.724, p<0.001) correlated with age, respectively. In those aged 40-59 years, both TAM-e' (p=0.002) and MAM-e' (p=0.048) in females were significantly higher than those in males. The gender differences diminished in the ≥60 years age groups.There was no age-associated decline in TAM-s', while TAM-e' varied with age and gender as did MAM-e'. Although the same criteria for the TAM-s' can be used for identifying abnormal RV systolic function regardless of age and gender, age and gender differences must be considered when one utilizes the TAM-e' for the diagnosis or management of cardiovascular disease.
- A digital multigate Doppler method for high frequency ultrasound. [Journal Article, Research Support, Non-U.S. Gov't]
- Sensors (Basel) 2014; 14(8):13348-60.
Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW) Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method.
- Shunt Flow Evaluation in Congenital Heart Disease Based on Two-Dimensional Speckle Tracking. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Jul 9.
High-frame-rate ultrasound speckle tracking was used for quantification of peak velocity in shunt flows resulting from septal defects in congenital heart disease. In a duplex acquisition scheme implemented on a research scanner, unfocused transmit beams and full parallel receive beamforming were used to achieve a frame rate of 107 frames/s for full field-of-view flow images with high accuracy, while also ensuring high-quality focused B-mode tissue imaging. The setup was evaluated in vivo for neonates with atrial and ventricular septal defects. The shunt position was automatically tracked in B-mode images and further used in blood speckle tracking to obtain calibrated shunt flow velocities throughout the cardiac cycle. Validation toward color flow imaging and pulsed wave Doppler with manual angle correction indicated that blood speckle tracking could provide accurate estimates of shunt flow velocities. The approach was less biased by clutter filtering compared with color flow imaging and was able to provide velocity estimates beyond the Nyquist range. Possible placements of sample volumes (and angle corrections) for conventional Doppler resulted in a peak shunt velocity variations of 0.49-0.56 m/s for the ventricular septal defect of patient 1 and 0.38-0.58 m/s for the atrial septal defect of patient 2. In comparison, the peak velocities found from speckle tracking were 0.77 and 0.33 m/s for patients 1 and 2, respectively. Results indicated that complex intraventricular flow velocity patterns could be quantified using high-frame-rate speckle tracking of both blood and tissue movement. This could potentially help increase diagnostic accuracy and decrease inter-observer variability when measuring peak velocity in shunt flows.