What intracardiac pressures can be calculated using a continuous wave Doppler (Doppler) spectrum of mitral regurgitation (MR)?

From the Guidelines

Using continuous wave Doppler spectrum of mitral regurgitation, you can calculate left ventricular systolic pressure and estimate left atrial pressure, which allows determination of the systolic pressure gradient across the mitral valve. The primary calculation involves using the simplified Bernoulli equation (4v²), where v is the peak velocity of the mitral regurgitation jet in meters per second. This equation gives the pressure gradient between the left ventricle and left atrium during systole. To determine absolute left ventricular systolic pressure, you need to add the estimated left atrial pressure (typically 8-12 mmHg in normal individuals, or can be estimated from clinical parameters or other echocardiographic measurements) to the calculated pressure gradient. For example, if the peak mitral regurgitation velocity is 5 m/s, the pressure gradient would be 4 × (5)² = 100 mmHg. Adding an estimated left atrial pressure of 10 mmHg would give a left ventricular systolic pressure of 110 mmHg. This calculation is particularly useful for estimating pulmonary artery systolic pressure when combined with tricuspid regurgitation measurements and for assessing the severity of mitral regurgitation, as supported by the most recent guidelines 1.

Some key points to consider when interpreting the results include:

• The presence of a large jet with a wide vena contracta and large proximal flow convergence zone may indicate severe mitral regurgitation 1
• The use of single-frame PISA in early systole may overestimate MR severity in certain cases, such as late systolic MR or biphasic MR 1
• The calculation of effective regurgitant orifice area by PISA may also be affected by the timing of the MR jet, and alternative methods such as Doppler vena contracta width may be more accurate 1
• The severity of mitral regurgitation can be classified based on quantitative measures such as regurgitant volume, regurgitant fraction, and regurgitant orifice area, as outlined in the guidelines 1

Overall, the use of continuous wave Doppler spectrum of mitral regurgitation provides valuable information for assessing the severity of mitral regurgitation and estimating left ventricular systolic pressure and left atrial pressure.

From the Research

Intracardiac Pressures Calculated Using Continuous Wave Doppler Spectrum of Mitral Regurgitation

• Left atrial pressure can be estimated by subtracting the peak mitral regurgitant pressure gradient from peak brachial systolic blood pressure 2
• Left ventricular end-diastolic pressure can be estimated by subtracting the aortic regurgitant gradient from diastolic blood pressure 3
• Left ventricular dP/dt (the instantaneous first derivative of left ventricular pressure) can be estimated using the continuous-wave Doppler mitral regurgitant velocity curve 4
• Left ventricular end-diastolic pressure can also be estimated using the difference between the duration of pulmonary vein and mitral A waves (A'-A) 5
• The time constant of left ventricular relaxation (tau) can be estimated using the continuous-wave Doppler velocity profile of mitral regurgitation 6

Parameters Used for Calculation

• Peak mitral regurgitant velocity
• Peak brachial systolic blood pressure
• Aortic regurgitant gradient
• Diastolic blood pressure
• Mitral regurgitant velocity curve
• Pulmonary vein and mitral A waves duration

Studies Supporting These Calculations

• 2, 3, 4, 5, 6 provide evidence for the noninvasive estimation of intracardiac pressures using continuous wave Doppler spectrum of mitral regurgitation.