Pulsed Doppler Signal Processing for use in Mice: Design and Evaluation

Reddy, Anilkumar K.; Jones, A. D.; Martono, C.; Caro, W.A.; Madala, Sridhar; Hartley, Craig J.

doi:10.1109/tbme.2005.855710

Cited by 22 publications

(17 citation statements)

References 17 publications

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“…The Indus software can also calculate a waveform of the spectral peak velocity for export along with the auxiliary signals for further processing by other analysis packages such as Excel. The best velocity resolution is 5 mm/s at 20 MHz, the maximum measurable velocity is 9.3 m/s at 10 MHz, and the best temporal resolution is 0.1 ms (46). Most ultrasonic imaging systems also have spectral Doppler capability, and many of the measurements illustrated here can be made with those systems.…”

Section: Murine Doppler Systemmentioning

confidence: 99%

“…The resulting sample volume is Ͻ0.02 l (0.3 mm diameter ϫ 0.3 mm long) at the focal point. The Doppler signal processor is a computer-based system that was designed in collaboration with Indus Instruments, Webster, TX (46,49). The current generation system digitizes and stores the audio Doppler signals at 125 kHz from up to four probes, generates and displays a complex fast Fourier transform in real time, and also captures and displays auxiliary signals such as ECG and pressure.…”

Section: Murine Doppler Systemmentioning

confidence: 99%

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Doppler velocity measurements from large and small arteries of mice

Hartley

Reddy

Madala

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

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Hartley CJ, Reddy AK, Madala S, Entman ML, Michael LH, Taffet GE. Doppler velocity measurements from large and small arteries of mice. Am J Physiol Heart Circ Physiol 301: H269 -H278, 2011. First published May 13, 2011; doi:10.1152/ajpheart.00320.2011With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans. peripheral vascular flow; pulse wave velocity; coronary flow reserve; transverse aortic constriction; pressure overload hypertrophy THIS REVIEW ARTICLE is part of a collection on Assessing Cardiovascular Function in Mice: New Developments and Methods. Other articles appearing in this collection, as well as a full archive of all Review collections, can be found online at http://ajpheart.physiology.org/.The ability to alter the genotype of the mouse has produced numerous models for studying cardiovascular physiology and pathophysiology and has generated a need to evaluate the changes that occur in mice during phenotypic development and maturation (8). The genetic manipulations can alter the structure, anatomy, pathology, and physiology of cells, organs, or systems in ways that can be subtle and unpredictable and that often change with time (6, 33). The major problems in adapting existing methods for use in mice relate to the small size and high heart rates that place extreme demands on both spatial and temporal resolution (10). We will focus here on noninvasive ultrasonic Doppler methods, w...

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Section: Murine Doppler Systemmentioning

confidence: 99%

Section: Murine Doppler Systemmentioning

confidence: 99%

Doppler velocity measurements from large and small arteries of mice

Hartley

Reddy

Madala

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

show abstract

“…In this orientation, the sound beam was nearly parallel to the axis of the left main coronary artery such that angle correction was not used to calculate velocity from the Doppler frequency. After a stable signal was achieved, a two-second sample of the ECG and the raw quadrature Doppler signals was acquired and stored in a computer file for later analysis (Reddy et al, 2005b;Reddy et al, 2005a). Then the isoflurane was reduced to 1% to lower coronary flow to a baseline level.…”

Section: Animal Protocolmentioning

confidence: 99%

“…These settings allow the measurement of velocities as high as 4.5 m/s at a maximum sample volume depth of 6 mm. The quadrature audio signals from the pulsed Doppler were connected to the Doppler signal processing workstation (Model DSPW, Indus Instruments, Houston, TX, USA) (Reddy et al, 2005a).…”

Section: Instrumentation and Data Analysismentioning

confidence: 99%

Effects of Isoflurane on Coronary Blood Flow Velocity in Young, Old and ApoE−/− Mice Measured by Doppler Ultrasound

Hartley

Reddy

Madala

et al. 2007

Ultrasound in Medicine & Biology

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The commonly used anesthetic agent, isoflurane (ISO), is a potent coronary vasodilator which could potentially be used in the assessment of coronary reserve, but its effects on coronary blood flow in mice are unknown. Coronary reserve is reduced by age, coronary artery disease, and other cardiac pathologies in man, and some of these conditions can now be modeled in mice. Accordingly, we used Doppler ultrasound to measure coronary flow velocity in mice anesthetized at low (1%) and at high (2.5%) levels of ISO to generate baseline (B) and elevated hyperemic (H) and Y and between A and O were significant (P < 0.01), while the differences in hyperemic velocities were not (P > 0.05). H/B was higher in old mice due to decreased baseline flow rather than increased hyperemic flow velocity. In contrast ApoE −/− mice have increased baseline and hyperemic velocities perhaps due to coronary lesions. The differences in baseline velocities between young and old mice could be due to age-related changes in basal metabolism or to differential sensitivity to isoflurane. We conclude that Doppler ultrasound combined with coronary vasodilation via isoflurane could provide a convenient and noninvasive method to estimate coronary reserve in mice, but also that care must be taken when assessing coronary flow in mice under isoflurane anesthesia because of its potent coronary vasodilator properties.

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“…PWV was determined by dividing the separation distance of measurement points by the time taken to travel this distance as measured from R-peaks of the electrocardiogram. 9 Blood pressure Blood pressure was measured by left ventricular catheterization as previously described. 10 After isoflurane sedation, mice were anesthetized with an intraperitoneal injection of urethane (800 mg/kg), etomidate (5 mg/kg) and morphine (2 mg/kg), and were mechanically ventilated.…”

Section: Aortic Stiffnessmentioning

confidence: 99%

Leptin is essential in maintaining normal vascular compliance independent of body weight

et al. 2009

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The adipocytokine leptin centrally regulates body weight by enhancing metabolic rate and signaling satiety, but it also has wideranging peripheral effects. Leptin receptors are expressed on vascular smooth muscle cells and have a role in maintaining vascular tone. We investigated the vascular effects of leptin repletion or calorie restriction on leptin-deficient mice (ob/ob) and a leptin antagonist on wild-type (WT) mice. Aortic compliance was assessed by the measurement of pulse wave velocity by noninvasive Doppler; blood pressure was measured by left ventricular catheterization. We found that ob/ob mice have much stiffer aortas than WT mice and that reduction in aortic stiffness was greater in ob/ob mice treated with leptin vs calorie restriction, despite similar weight loss. Interestingly, treating WT mice with a leptin antagonist increases aortic stiffness with no change in weight. Thus, we conclude that leptin is essential for maintaining normal aortic compliance independent of body weight.

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Pulsed Doppler Signal Processing for use in Mice: Design and Evaluation

Cited by 22 publications

References 17 publications

Doppler velocity measurements from large and small arteries of mice

Doppler velocity measurements from large and small arteries of mice

Effects of Isoflurane on Coronary Blood Flow Velocity in Young, Old and ApoE−/− Mice Measured by Doppler Ultrasound

Leptin is essential in maintaining normal vascular compliance independent of body weight

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