RVSP (how to) - Saving Lives With Sound

How to measure RVSP

Pulmonary hypertension is associated with significant morbidity and mortality in critically ill patients. Right ventricular systolic pressure (RVSP) is a surrogate for pulmonary artery systolic pressure (PASP). Please see the “echo in pulmonary hypertension” video for more. Echo offers a non-invasive means of assessing for the presence of elevated RVSP, indicating the presence of pulmonary hypertension.

This tutorial will review how to obtain and interpret a right ventricular systolic pressure (RVSP) from a tricuspid regurgitant jet. We will also review assumptions and caveats in the interpretation.

Step 1. Examine for the presence of tricuspid regurgitation

Detect color signal

Place the color Doppler box over the apical portion of the tricuspid valve and over the receiving chamber (right atrium). Tricuspid regurgitation is identified by seeing a narrow mixed-colour (“mosaic”) jet that is directed towards the right atrium. This is secondary to rapid transit of blood and “aliasing” as the blood speeds up through a narrow regurgitant orifice.

Use multiple windows

Examine for TR from multiple acoustic windows: parasternal short axis (base level), subcostal short-axis, parasternal RV inflow, and apical 4-chamber.

This ensures you optimize alignment of the tricuspid regurgitant jet with the interrogation angle of the Doppler beam. It also may help identify the predominant TR jet.

STep 2. Place the CW doppler line/gate through the vena contracta of the regurgitant jet

Place CW gate

Place the continuous wave (CW) Doppler gate through the vena contracta. CW lacks range specificity, so the potential for confounding or mixing the measured velocitie is real. Colour helps identify the narrowest portion or “neck” of the jet and has the fastest velocity profile. Be sure that the Doppler interrogation angle is <20 degrees.

Be aware there may be multiple jets that exist in different planes along the 3D structure of the valve itself.

Step 3. Acquire the spectral doppler image

acquire cw spectral image

Here you have acquired the CW spectral signal. This records a filled-in CW Doppler profile that displays the full spectrum of velocity of blood across the valve. Adjust the baseline (yellow line here) and scale to ensure the full Doppler envelope is shown. Notice the smooth parabolic profile of this non-severe TR.

The lowest tip of this profile records the fastest velocity or the “peak instantaneous gradient” of blood flowing from the RV to the RA.

Step 4. Interpret your findings.

The fastest TR velocity

Next, permitting there is sufficient TR, you will obtain a clean Doppler profile. You will place a cross-hair to measure from the baseline to the lowest point on the profile (“peak-velocity”). This records a peak-gradient (PG), as this is the maximal point of velocity of blood between 2 chambers. Make sure the Doppler gain is adjusted to prevent the envelope from extending beyond its true margins.

Here the PG is ~37 mm Hg. This can also be calculated by using the velocity measurement of 304 cm/s or 3.04 m/s.
The modified Bernouilli equation is the calculation required to convert velocities into pressure gradients and it is = 4 multipled by velocity squared= 4 x 3.04 (squared)= 37 mm Hg.

As noted above, you will likely interrogate multiple windows for tricuspid regurgitation to both find the optimal vena contracta and the optimal angle. You will also apply CW at the TR vena contracta in these multiple views; the fastest peak TR velocity amongst all these views is the one that is selected to calculate a peak gradient in step 5.

Step 5. convert peak gradient into a right ventricular systolic pressure

add right atrial pressure

Your peak gradient is added to RAP to calculate your right ventricular systolic pressure (RVSP). The diagram shown demonstrates how to grossly calculate this in a spontaneously breathing patient. If the patient is mechanically ventilated, the best way to collect the RAP is through the central venous pressure measurement.

If there is no obstruction at the outflow tract of the RV, then the RVSP will equal the pulmonary artery systolic pressure (PASP).

Assumptions & caveats

1. there is no pulmonic stenosis

When there is an additional gradient between the RV and pulmonary artery, it cannot be assumed that RVSP=PASP. More advanced considerations come into play in examining gradients in tandem.

2. There is sufficient tricuspid regurgitation to measure a signal

Without a sufficient TR signal, RVSP cannot be calculated from this method. While a signal may be produced, its reliability may be in question. The signal may be able to be enhanced with agitated saline or other contrast agents, but this is often omitted in caring for patients in duress, as there may be other manifestations of elevated RV pressures or RV dysfunction.

3. The tricuspid regurgitation is not "severe"

Severe TR with a dense triangular and/or early peaking may mean that regurgitation is so severe that the assumptions of Modified Bernoulli are no longer accurate (and the gradient may cease to exist). SPAP is unlikely to be estimated from this type of TR signal.

4. You have adequately measured the right atrial pressure

Measurements of RAP in a spontaneously breathing patient are relatively simple to perform, but maybe a crude measure of actual RAP. There are other potential strategies to estimate RAP, but are beyond the scope of this website.

References

Amsallem M, Sternbach JM, Adigopula S, et al. Addressing the Controversy of Estimating Pulmonary Arterial Pressure by Echocardiography. Journal of the American Society of Echocardiography. 2016;29(2):93-102. doi:10.1016/j.echo.2015.11.001

Anavekar NS, Oh JK. Doppler echocardiography: A contemporary review. Journal of Cardiology. 2009;54(3):347-358. doi:10.1016/j.jjcc.2009.10.001

Mitchell C, Rahko PS, Blauwet LA, et al. Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. Journal of the American Society of Echocardiography. 2019;32(1):1-64. doi:10.1016/j.echo.2018.06.004

Narasimhan M, Koenig SJ, Mayo PH. Advanced echocardiography for the critical care physician: Part 2. Chest. 2014;145:135-142. doi:10.1378/chest.12-2442

Porter TR, Shillcutt SK, Adams MS, et al. Guidelines for the use of echocardiography as a monitor for therapeutic intervention in adults: A report from the american society of echocardiography. Journal of the American Society of Echocardiography. 2015;28(1):40-56. doi:10.1016/j.echo.2014.09.009