Doppler Ultrasound Method
This method uses ultrasound and the Doppler effect to measure Q. The blood velocity through the heart causes a 'Doppler shift' in the frequency of the returning ultrasound waves. This Doppler shift can then be used to calculate flow velocity and volume and effectively Q using the following equations:
- Q = SV × HR
- SV = vti × CSA
where:
- CSA = valve orifice cross sectional area; use pr²
- r = valve radius
- vti = the velocity time integral of the trace of the Doppler flow profile
Doppler ultrasound is non-invasive, accurate and inexpensive and is a routine part of clinical ultrasound with high levels of reliability and reproducibility having been in clinical use since the 1960s.
Read more about this topic: Cardiac Input, Measuring Cardiac Output
Famous quotes containing the word method:
“The method of painting is the natural growth out of a need. I want to express my feelings rather than illustrate them. Technique is just a means of arriving at a statement.... I can control the flow of paint: there is no accident, just as there is no beginning and no end.”
—Jackson Pollock (1912–1956)