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[Comparison of Doppler echocardiographic methods of determining cardiac minute volume]
H Dittmann1, W Voelker, K R Karsch
1Medizinische Klinik III, Eberhard-Karls-Universität Tübingen.
Insights
Pulsed Doppler echocardiography accurately measures cardiac output in patients without valvular disease. Left ventricular outflow tract measurements showed the best correlation with thermodilution, offering a reliable non-invasive method.
Area of Science:
- Cardiology
- Medical Imaging
- Hemodynamics
Background:
- Accurate cardiac output (CO) measurement is crucial for cardiovascular assessment.
- Thermodilution is a standard CO measurement technique.
- Non-invasive methods like Doppler echocardiography are sought for CO determination.
Purpose of the Study:
- To evaluate the accuracy of pulsed Doppler echocardiography in measuring cardiac output.
- To compare Doppler-derived CO with simultaneous thermodilution measurements.
- To identify the optimal Doppler echocardiography method for CO assessment.
Main Methods:
- Simultaneous measurement of cardiac output using pulsed Doppler echocardiography and thermodilution in 40 patients without valvular disease.
- Doppler sample volume placed at mitral valve and left ventricular outflow tract (LVOT).
- Calculation of cross-sectional areas from echocardiographic diameters; CO derived from time-velocity integrals and heart rate.
Main Results:
- Thermodilution CO ranged from 4.0 to 10.2 L/min.
- All Doppler methods showed significant correlation with thermodilution.
- LVOT measurements using M-mode aortic ring diameter for area yielded the highest correlation (r=0.93) and lowest standard error (0.589 L/min).
Conclusions:
- Pulsed Doppler echocardiography is a reliable non-invasive method for cardiac output determination.
- Doppler measurements in the left ventricular outflow tract, with area derived from M-mode aortic ring, offer the most accurate assessment.
- This technique provides a valuable alternative to invasive methods for cardiac output evaluation.
Abstract:
In 40 patients without valvular disease, cardiac output was determined by pulsed Doppler echocardiography and thermodilution simultaneously. The sample volume was located in the center of the mitral valve ring, at the tips of the mitral leaflets and in the left ventricular outflow tract, directly proximal to the aortic valve leaflets. Circular cross-sectional areas of the mitral valve ring, aortic ring and bulbus of the aorta were calculated from the M-mode and two dimensional echocardiographic diameters. The mitral orifice was assumed to be an ellipse with varying short axes, determined as the mean diastolic leaflet separation in the M-mode and a constant long axis, derived from the maximal mitral orifice area or mitral ring diameter. Cardiac output was calculated by multiplying time-velocity integrals with different areas and heart rate. Cardiac output, measured by the thermodilution technique, ranged from 4.0 l/min to 10.2 l/min. Cardiac output determined by the different Doppler methods correlated significantly with the thermodilution measurements. Cardiac output measurements in the left ventricular outflow tract provided the best correlation coefficient (0.93) and a standard error of the estimate of 0.589 l/min, when the circular flow area was derived from the M-mode echo of the aortic ring.(ABSTRACT TRUNCATED AT 250 WORDS)