Effective Regurgitant Orifice by Continuity Equation in Pulmonary Regurgitation
Formula:RVOT SV = (0.785 * RVOT Diameter²) * RVOT VTITV SV = (0.785 * TV Diameter²) * TV VTIRV = RVOT SV - TV SVERO = RV / RJ VTI
How to get Effective Regurgitant Orifice by Continuity Equation in Pulmonary Regurgitation.
Measure the Diameter of the RVOT. The diameter can be of the RVOT should be obtained from the midesophageal RVIO view, in mid systole, and under the zoom mode. The view of the RVOT should not be an obtuse angle view. The pulmonic valve leaflets should be clearly seen. The zoom mode will decrease the error present in the calculation. Since the RVOT diameter changes throughout systole, the mid systole measurement should be obtained.
Obtain a VTI of the RVOT. The VIT of the RVOT is obtained from a PWD of the RVOT. The PWD of the RVOT should be obtained at the same location as the RVOT diameter measurement. The PWD beam should not be off more than 15Â° from parallel to the RVOT flow. After tracing the flow on the echocardiographic machine, a VTI of the PWD tracing will be calculated. A continuous wave doppler (CWD) of the RVOT could be obtained, but, since the CWD introduces ambiguity into the equation and since flows in the RVOT rarely exceed the aliasing velocity of the pulse wave doppler, PWD is the best measurement mode. However, in aortic regurgitation, there is excessive flow, so aliasing may occur. Therefore, CWD may be required to be able to trace the whole flow profile.
Obtain a Tricuspid Valve Diameter. The area of the tricuspid valve can be calculated from this measurement. This enter some inaccuracy into the equation since the mitral valve is not a circle (it is oval). Therefore, the aortic valve could be used instead. This measurement is to be used to generate a value that represents normal forward flow in the cardiac cycle.
Obtain a Tricuspid Valve VTI. Using the PWD mode, trace the envelope of the entire (E wave and A wave) flow profile of the mitral valve. The diastolic flow profile is the TV VTI whereas the systolic flow profile is the regurgitant jet VTI (RJVTI).