Noninvasive measurement of ascending aortic blood velocity in mice

Abstract

Mice are useful models in numerous research protocols, but monitoring cardiovascular parameters in small animals is difficult. Therefore we evaluated the use of 20-MHz pulsed Doppler ultrasound to measure ascending aortic blood velocity in intact anesthetized mice. Using a 0.5-mm-diameter 20-MHz transducer applied to the right sternal border, we recorded audio Doppler signals from the ascending aorta of 31 mice [24.4 +/- 1.5 (SD) g body wt]. The signals were played back at speed into a fast Fourier transform analyzer from which we measured heart rate (453 +/- 96 beats/min), ejection time (38 +/- 3%), peak velocity (90 +/- 11 cm/s), mean velocity (23 +/- 4 cm/s), rise time (7.3 +/- 2 ms), stroke distance (29 +/- 7 mm), and acceleration (163 +/- 63 m/s2) from the spectral envelopes. We determined aortic diameter (1.2 +/- 0.2 mm) and Doppler angle (0-20 degrees) in six mice by molding the aortic root and major systemic vessels with casting resin infused at 100 mmHg pressure. For an aortic diameter of 1.2 mm, cardiac output was estimated to be 14.8 ml/min and stroke volume to be 33 microliters. To verify the origin of the signals and to test responsiveness to known stimuli, we measured velocity signals from the aorta and other nearby vessels and varied heart rate and aortic velocity by warming or by infusion of isoproterenol in three open-chest animals. For the noninvasive applications, acoustic coupling was adequate through the moistened fur, and aortic velocity signals were obtained in all animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Comprehensive transthoracic cardiac imaging in mice using ultrasound biomicroscopy with anatomical confirmation by magnetic resonance imaging

“…From the upper right parasternal window, the entire ascending aorta can be visualized with a small intercept angle between the Doppler beam and the long axis of aorta, and the aortic velocity can be measured exactly from any desired site. The aortic peak velocity in our study is higher than those (50ϳ75 cm/s) measured from apical four-chamber view in previous studies (15,25,31) but similar to those measured with a small pure Doppler probe from the suprasternal notch (90 Ϯ 11 cm/s), where the incidence angle between the ultrasound beam and ascending aorta was assumed to be close to zero (13).…”

“…The left ventricular systolic function can be evaluated based on the parameters derived from M-mode dimension measurements (7). Doppler flow spectra obtained from the ascending aorta can be used for measuring the parameters such as the peak flow velocity, rising time, peak acceleration rate, and ejection time to assess the left ventricular systolic function (13). Accordingly, the pulmonary arterial Doppler flow spectrum as obtained in this study can be used to evaluate the right ventricular systolic function in a similar way.…”

Fibroblast growth factor-2 mediates pressure-induced hypertrophic response

“…Echocardiographic measurements, gravimetry, and cardiomyocyte cross-sectional area reveal that an absence of FGF2 results in a statistically lesser degree of hypertrophy during pressure overload (Figures 2a, 3, and 4). Owing to their noninvasive technique and the ability to evaluate cardiac disease and function in a serial fashion, M-mode and pulsedwave Doppler echocardiography are excellent methods for measuring LV mass, LV function, and aortic blood flow velocities (30)(31)(32)(33). We have used this noninvasive application to assess the weekly progression of cardiac hypertrophy after transverse AC of Fgf2 +/+ and Fgf2 -/-mice.…”

Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice.

“…M-mode and Doppler echocardiography were performed in the DeBakey Heart Center Core Animal Laboratory by a technician who was blinded to mouse genotype (32)(33)(34)(35). In brief, mice were anesthetized lightly by intraperitoneal injection of 10 g/ml dilution of pentobarbital sodium at the dose of 10 l/g.…”