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1. Ultrasound assessment of the force-frequency relationship from the law of conservation of momentum in patients with left ventricular dysfunction.

Author

Dini FL, Guarini G, Pedrizzetti G, Miccoli M, Zito MC, Baggiani A, Conti U, Di Bello V, and Marzilli M

Subjects
Algorithms, Coronary Circulation, Exercise Test, Female, Heart Function Tests methods, Humans, Male, Middle Aged, Reproducibility of Results, Sensitivity and Specificity, Stress, Mechanical, Echocardiography, Doppler methods, Heart Rate, Image Interpretation, Computer-Assisted methods, Myocardial Contraction, Stroke Volume, Ventricular Dysfunction, Left diagnostic imaging, Ventricular Dysfunction, Left physiopathology
Abstract

Measurement of force-frequency relationship (FFR) is useful in the evaluation of heart rate-dependent contractile dysfunction. The purpose of this study was to evaluate a new Doppler-derived method for assessing FFR. Doppler velocity spectra at the left ventricular (LV) outflow tract was used to estimate mean blood flow velocity (mBFV), ejection time (ET) and velocity-time integral. LV ejection force (LVF) was then calculated according to the law of conservation of momentum: 1060 kg/m³ × (mBFV[m/sec]/ET [s]) × Stroke volume (mL). A symptom-limited, graded, bicycle semi-supine exercise test was performed in 56 patients with LV dysfunction (LV ejection fraction = 27 ± 6%). Measurements were obtained at baseline and serially during the test. The change in FFR was defined as up-sloping when the peak LVF was higher than the baseline value. The change was biphasic when the trend was initially up-sloping, then down-sloping; it was flat or negative when peak LVF was less than the baseline value. LVF was 30 ± 12 mN in patients with up-sloping FFR (n = 39) and 15 ± 6 mN in those with biphasic or flat FFR (n = 17; p < 0.0001). The ultrasound assessment of the FFR was highly concordant with a previously validated method based on pressure-end-systolic volume index ratio (κ = 0.75; 95% confidence interval, 0.55-94.0). The evaluation of the LVF using Doppler is an alternative method for the assessment of FFR during stress echocardiography in patients with LV dysfunction., (Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Published
2013
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2. Ultrasound assessment of the force-frequency relationship from the law of conservation of momentum in patients with left ventricular dysfunction

Author

Mario Marzilli, Angelo Baggiani, Vitantonio Di Bello, Maria Cristina Zito, Frank Lloyd Dini, Gianni Pedrizzetti, Mario Miccoli, Umberto Conti, Giacinta Guarini, Dini, Fl, Guarini, G, Pedrizzetti, Gianni, Miccoli, M, Zito, Mc, Baggiani, A, Conti, U, Di Bello, V, and Marzilli, M.

Subjects
Male, medicine.medical_specialty, Acoustics and Ultrasonics, Biophysics, Sensitivity and Specificity, cardiac mechanics, symbols.namesake, Ventricular Dysfunction, Left, Heart Rate, Internal medicine, Coronary Circulation, Image Interpretation, Computer-Assisted, medicine, Stress Echocardiography, Humans, Radiology, Nuclear Medicine and imaging, Mean Blood Flow Velocity, Radiological and Ultrasound Technology, business.industry, Ultrasound, Reproducibility of Results, Dilated cardiomyopathy, Stroke Volume, Stroke volume, Middle Aged, medicine.disease, Myocardial Contraction, Confidence interval, Echocardiography, Doppler, Heart failure, Heart Function Tests, symbols, Cardiology, Exercise Test, Female, Stress, Mechanical, business, Doppler effect, Algorithms
Abstract

Measurement of force-frequency relationship (FFR) is useful in the evaluation of heart rate-dependent contractile dysfunction. The purpose of this study was to evaluate a new Doppler-derived method for assessing FFR. Doppler velocity spectra at the left ventricular (LV) outflow tract was used to estimate mean blood flow velocity (mBFV), ejection time (ET) and velocity-time integral. LV ejection force (LVF) was then calculated ac- cording to the law of conservation of momentum: 1060 kg/m 3 3 (mBFV(m/sec)/ET (s)) 3 Stroke volume (mL). A symptom-limited, graded, bicycle semi-supine exercise test was performed in 56 patients with LV dysfunction (LVejection fraction 527 ± 6%). Measurements were obtained at baseline and serially during the test. The change in FFR was defined as up-sloping when the peak LVF was higher than the baseline value. The change was biphasic when the trendwas initially up-sloping, then down-sloping; it wasflat or negative when peak LVF was less than the baseline value. LVF was 30 ± 12 mN in patients with up-sloping FFR (n 5 39) and 15 ± 6 mN in those with biphasic or flat FFR (n 5 17; p , 0.0001). The ultrasound assessment of the FFR was highly concordant with a previously validated method based on pressure-end-systolic volume index ratio (k 5 0.75; 95% confidence interval, 0.55-94.0). The evaluation of the LVF using Doppler is an alternative method for the assessment of FFR during stress echocardiography in patients with LV dysfunction. (E-mail: f.dini@ao-pisa.toscana.it) � 2013 World Federation for Ultrasound in Medicine & Biology.

Published
2012

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