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Doppler flowmetry in the lower thoracic aorta. An indirect estimation of cardiac output
Insights
Doppler flowmetry in the lower thoracic aorta accurately estimates cardiac output. This non-invasive method is particularly useful for patients with aortic valve abnormalities, where other Doppler techniques may be impossible.
Area of Science:
- Cardiovascular Physiology
- Medical Imaging
- Diagnostic Techniques
Background:
- Estimating cardiac output is crucial for assessing heart function.
- Traditional methods like the Fick method can be invasive.
- Doppler ultrasound offers a potential non-invasive alternative.
Purpose of the Study:
- To evaluate the accuracy of Doppler flowmetry in the lower thoracic aorta for estimating cardiac output.
- To compare Doppler findings with the Fick method.
- To assess the influence of aortic valve abnormalities on Doppler accuracy.
Main Methods:
- Duplex scanning of the lower thoracic aorta was performed on 67 patients.
- Cardiac output was simultaneously estimated using the Fick method.
- Correlation between Doppler flowmetry and Fick method results was analyzed.
Main Results:
- Adequate Doppler signals were obtained in 88% of patients.
- A high correlation (r=0.89) was found between Doppler and Fick methods.
- Aortic valve abnormalities did not significantly affect Doppler accuracy.
Conclusions:
- Doppler flowmetry in the lower thoracic aorta is a reliable method for estimating resting cardiac output.
- This technique is especially valuable in patients with aortic valve lesions.
- It provides a useful non-invasive alternative to traditional methods.
Abstract:
Duplex scanning of the lower thoracic aorta was performed on 67 patients subjected to routine left and right heart catheterization with estimation of cardiac output ad modum Fick. Adequate Doppler signals from the lower thoracic aorta were obtained in 59 patients (88%), 26 of whom had aortic valve abnormality. A high correlation was found between the Doppler and Fick findings (r=0.89), with a regression line intercepting close to zero (cardiac output = 1.76 X Doppler flow +0.05). The presence of aortic valve abnormality did not seem to influence the accuracy of the Doppler flow results. It is concluded that Doppler flowmetry in the lower thoracic aorta is a useful method in estimation of resting cardiac output, especially in patients with aortic valve lesions making Doppler flowmetry in the ascending aorta impossible.