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Assessment of cardiac output by the Doppler ultrasound technique alone
Insights
This study establishes normal aortic blood velocity ranges in adults. Aortic blood velocity measurements offer a safe and simple method for assessing cardiac output, declining with age.
Area of Science:
- Cardiovascular Physiology
- Diagnostic Ultrasound
Background:
- Assessing cardiac output is crucial for cardiovascular health monitoring.
- Non-invasive methods are preferred for patient safety and ease of use.
Purpose of the Study:
- To establish normal ranges for aortic blood velocity in healthy adults.
- To evaluate the utility of aortic blood velocity derivatives in assessing cardiac output across different patient groups.
Main Methods:
- Utilized Doppler ultrasound to measure aortic blood velocity in 140 healthy adults.
- Calculated stroke distance and minute distance from the velocity-time curve and heart rate.
- Compared patient group data with age-corrected normal values.
Main Results:
- Aortic blood velocity and its derivatives (stroke distance, minute distance) showed a progressive decline with age (approx. 1% per annum).
- Stroke distance demonstrated significant differences in various patient groups: increased in pregnancy, normal post-myocardial infarction, and decreased in hypertension, atrial fibrillation, and cardiac failure.
- Aortic blood velocity measurement alone, without aortic size, proved effective in assessing cardiac output.
Conclusions:
- Aortic blood velocity measurement is a safe, simple, and physiologically valid non-invasive method for cardiac output assessment.
- Age-related decline in stroke distance and minute distance is observed.
- This technique effectively differentiates cardiac output in various pathological conditions.
Abstract:
The normal range of aortic blood velocity was established in 140 healthy adults, using a non-invasive Doppler ultrasound technique. Integration of the area under the velocity-time curve for each heart beat gave stroke distance, which, when multiplied by heart rate, gave minute distance. Stroke distance and minute distance are an indication of stroke volume and cardiac output respectively and both show a progressive decline with age of about 1% per annum of adult life. Stroke distance gave the greatest discrimination between patient groups and, compared with age corrected normal values, was increased by 43% in 12 pregnant women, normal in 16 patients convalescing after myocardial infarction, and decreased by 14% in 15 patients with hypertension, by 31% in 12 patients with atrial fibrillation, and by 43% in 13 patients with cardiac failure. Measurement of aortic blood velocity and its derivatives alone, without determination of aortic size, is a safe, simple, and physiologically valid way of assessing cardiac output.