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The continuity equation states that the flow in one area must equal the flow in a second area if there are no shunts between the two areas. In practical terms, the flow from the left ventricular outflow tract (LVOT) is compared to the flow at the level of the aortic valve.
Quantitative echo utilizes a number of equations to calculate aspects of the heart structure and function. Simplified Bernoulli equation and continuity equation are two common equations used. Others are used in grading valve function (e.g., EROA, PISA).
A continuity equation is the mathematical way to express this kind of statement. For example, the continuity equation for electric charge states that the amount of electric charge in any volume of space can only change by the amount of electric current flowing into or out of that volume through its boundaries.
Measurement of the vena contracta is useful in echocardiography, where it describes the smallest area of the blood flow jet as it exits a heart valve. This corresponds to the effective orifice area (EOA) calculated for heart valves using the continuity equation.
Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging, using standard ultrasound or Doppler ultrasound. [1] The visual image formed using this technique is called an echocardiogram, a cardiac echo, or simply an echo.
In physics a conserved current is a current, , that satisfies the continuity equation =.The continuity equation represents a conservation law, hence the name. Indeed, integrating the continuity equation over a volume , large enough to have no net currents through its surface, leads to the conservation law =, where = is the conserved quantity.
The standard for diagnosis of aortic stenosis is non-invasive testing with echocardiography. Cardiac catheterization is reserved for cases in which there is a discrepancy between the clinical picture and non-invasive testing, due to risks inherent to crossing the aortic valve, such as stroke.
The definition of probability current and Schrödinger's equation can be used to derive the continuity equation, which has exactly the same forms as those for hydrodynamics and electromagnetism. [6] For some wave function Ψ, let: