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pulsed wave Doppler ultrasound pulsed Doppler ultrasound [keywords]
- Transplantation of pulmonary valve using a mouse model of heterotopic heart transplantation. [Journal Article]
- 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]
- 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.
- Prenatal findings in total anomalous pulmonary venous return: a diagnostic road map starts with obstetric screening views. [Journal Article]
- J Ultrasound Med 2014 Jul; 33(7):1193-207.
Optimal perinatal management of total anomalous pulmonary venous return (TAPVR) involves timely identification followed by surgical correction. Antenatal diagnosis, however, has long been a challenge. We aimed to identify consistent prenatal sonographic features in this condition in a large cohort in whom the diagnosis was made antenatally and confirmed postnatally.We conducted a systematic retrospective review of the 2-dimensional and Doppler sonographic features that had helped make the diagnosis of TAPVR at our institution from 2001 to 2012.Twenty-six patients had prenatal diagnosis of TAPVR (mean gestational age, 24.1 weeks). Four of the fetuses with a prenatal diagnosis represented isolated cases of TAPVR; 22 had heterotaxy syndrome, additional cardiac abnormalities, or both. Prenatally diagnosed abnormal pulmonary venous connections were supracardiac (type I) in 18 cases, cardiac (type II) in 1, and infradiaphragmatic (type III) in 7. Lack of a visible connection of the pulmonary veins to the atrium (100%) and the presence of a visible venous confluence on axial 4-chamber views (96%) were the most consistent findings. Cardiac asymmetry and the presence of additional vertical venous channels on 3-vessel or axial abdominal views were also noted but less consistently. Abnormal pulmonary venous spectral Doppler findings were present in 25 of the 26 fetuses.The diagnosis of TAPVR can be suspected on standard axial views included in second-trimester obstetric screening examinations of the fetal heart and confirmed on fetal echocardiography with the use of pulsed wave Doppler imaging. Clues recognizable on obstetric sonographic screening have the potential to contribute to increasing the diagnostic yield for prenatal detection of TAPVR.
- Echocardiography and conventional Doppler examination in clinically healthy adult Cavalier King Charles Spaniels: effect of body weight, age, and gender, and establishment of reference intervals. [Journal Article]
- J Vet Cardiol 2014 Jun; 16(2):91-100.
The objectives of this study were (1) to assess the potential effect of body weight (BW), age, and gender on the most commonly used echocardiographic and conventional Doppler variables in a large population of healthy Cavalier King Charles Spaniels (CKCS), and (2) to establish the corresponding reference intervals (RI).134 healthy adult CKCS.Ultrasound examinations were performed by trained observers in awake dogs. M-mode variables included left ventricular (LV) end-diastolic and end-systolic diameters, LV free wall and interventricular septal thicknesses at end-diastole and end-systole, and LV fractional shortening (FS%). The left atrium (LA) and aortic (Ao) diameters were measured using a 2D method, and the LA/Ao was calculated. Pulsed-wave Doppler variables included peak systolic aortic and pulmonary flow velocities, mitral E and A waves, and E/A ratio. Effects of BW, age, and gender on these 15 variables were tested using a general linear model, and RIs were determined by applying the statistical procedures recommended by the Clinical and Laboratory Standards Institute.A significant BW effect was observed for all variables, except LA/Ao, FS%, and mitral E/A ratio. A significant but negligible effect of gender and age was also observed for 5/15 and 4/15 of the tested variables, respectively. Only the BW effect on M-mode variables was considered as clinically relevant and the corresponding regression-based RIs were calculated.Body weight should be taken into account when interpreting echocardiographic values in CKCS, except for LA/Ao, FS%, and mitral E/A ratio.
- Acoustically Active Injection Catheter Guided by Ultrasound: Navigation Tests in Acutely Ischemic Porcine Hearts. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Apr 27.
Catheters are increasingly used therapeutically and investigatively. With complex usage comes a need for more accurate intracardiac localization than traditional guidance can provide. An injection catheter navigated by ultrasound was designed and then tested in an open-chest model of acute ischemia in eight pigs. The catheter is made "acoustically active" by a piezo-electric crystal near its tip, electronically controlled, vibrating in the audio frequency range and uniquely identifiable using pulsed-wave Doppler. Another "target" crystal was sutured to the epicardium within the ischemic region. Sonomicrometry was used to measure distances between the two crystals and then compared with measurements from 2-D echocardiographic images. Complete data were obtained from seven pigs, and the correlation between sonomicrometry and ultrasound measurements was excellent (p < 0.0001, ρ = 0.9820), as was the intraclass correlation coefficient (0.96) between two observers. These initial experimental results suggest high accuracy of ultrasound navigation of the acoustically active catheter prototype located inside the beating left ventricle.
- Combined Vector Velocity and Spectral Doppler Imaging for Improved Imaging of Complex Blood Flow in the Carotid Arteries. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Apr 27.
Color flow imaging and pulsed wave (PW) Doppler are important diagnostic tools in the examination of patients with carotid artery disease. However, measurement of the true peak systolic velocity is dependent on sample volume placement and the operator's ability to provide an educated guess of the flow direction. Using plane wave transmissions and a duplex imaging scheme, we present an all-in-one modality that provides both vector velocity and spectral Doppler imaging from one acquisition, in addition to separate B-mode images of sufficient quality. The vector Doppler information was used to provide automatically calibrated (angle-corrected) PW Doppler spectra at every image point. It was demonstrated that the combined information can be used to generate spatial maps of the peak systolic velocity, highlighting regions of high velocity and the extent of the stenotic region, which could be used to automate work flow as well as improve the accuracy of measurement of true peak systolic velocity. The modality was tested in a small group (N = 12) of patients with carotid artery disease. PW Doppler, vector velocity and B-mode images could successfully be obtained from a single recording for all patients with a body mass index ranging from 21 to 31 and a carotid depth ranging from 16 to 28 mm.
- Non-invasive cardiac output assessment in critically ill paediatric patients. [Journal Article]
- Acta Cardiol 2014 Apr; 69(2):167-73.
Recently, non-invasive methods for cardiac output (CO) assessment have been developed including the ultrasonic cardiac output monitor (USCOM). This technique uses the same concept as Doppler echocardiography but differs in two aspects including continuous wave (CW) Doppler and estimated outflow tract diameter (OTD) used in USCOM compared to pulsed wave Doppler and directed measurement of OTD used in echocardiography. We sought to assess the agreement between CO assessment by USCOM and echocardiography in critically ill paediatric patients.Paired measurements of CO in critically ill paediatric patients were simultaneously and independently obtained by USCOM and echocardiography. Agreement between OTD, velocity time integral (VTI), CO, and cardiac index (CI) were assessed by percentage error and Bland-Altman analysis.Thirty-four children (aged 7.86 +/- 5.78years, 44.1% male) had a mean OTD (1.47 +/- 0.38, 1.41 +/- 0.40), VTI (19.13 +/- 6.06, 23.53 +/- 7.31 cm), CO (3.88 +/- 2.19,4.41 +/- 2.83 l/min) and CI (4.23 +/- 1.19,4.77 +/- 1.43 l/min/m2) by echocardiography and USCOM, respectively. Bias +/- precision and percentage of error of OTD, VTI, CO, and CI were -0.07 +/- 0.20 cm, 27.80%; -4.40 +/- 3.84 cm, 31.99%; -0.53 +/- 1.23 l/min, 54.66%; and 0.54 +/- 1.03 l/min/m2, 42.32%, respectively. The bias +/- precision and percentage error were more important in patients with septic shock (n = 16).USCOM was an unreliable tool for absolute value measurement of CO and CI due to the errors of VTI by CW Doppler.