CASE 1:  Color Flow Doppler in Mitral Regurgitation

Submitted by
K. Carlos El-Tallawi MD and William A. Zoghbi MD
Houston Methodist DeBakey Heart & Vascular Center

History

• 65-year-old male with hypertension and hypercholesterolemia presented to the emergency department with atrial fibrillation and rapid ventricular response.
• He spontaneously cardioverted back to sinus rhythm.
• A transthoracic echocardiogram was obtained as part of his work-up.

The following are a set of video images and Doppler still frames. You are asked to grade the degree of mitral regurgitation (MR) and determine its etiology (primary or secondary).

Parasternal Long Axis

Parasternal Long Axis With Color Doppler

Apical Views

Apical Views with Color

Mitral Annulus                                                              Mitral Tip                                                                      CW Doppler of MR

Pulmonary Vein                                                           Pulsed Doppler LVOT

What is your assessment of the Mitral Regurgitation?

• Is MR mild, Moderate, Severe or Indeterminate in your opinion?
• What is the mechanism of MR: primary, secondary, indeterminate?

The study was read clinically as mild eccentric mitral regurgitation. No further recommendation was done. So if you stated that the MR is mild, you would have been in line with the clinical reader.

However, we must admit that the jet is VERY eccentric, directed anteriorly just under the anterior leaflet, raising the question of a primary MR mechanism. If you look carefully on the 2D images (in retrospect or because you see the very eccentric jet, you see occasionally some fine mobile echoes just behind the valve, ?possibly flail segment, but certainly not one that immediately is obvious. However, the “color jet” (flow convergence, vena contracta and eccentric jet area) and its effect in the left atrium are all quite Unimpressive.

History continued…

• He was admitted 1 week later for surgical treatment of a known cervical radiculopathy.
• After a reported febrile episode, a TEE was ordered to rule out a possible endocarditis (although not many supportive findings were present).

Esophageal Level

Pulmonary Vein                                                           LV Outflow

Re-Evaluate your assessment of the Mitral Regurgitation: 

• Is MR mild, Moderate, Severe or Indeterminate?
• What is the mechanism of MR: primary, secondary?

There is a definite flail of the posterior leaflet.
The mitral regurgitation was severe, although it did not have the other characteristics of severe MR: pulmonary vein flow reversal or high Mitral E velocity. The calculated Regurgitant volume by volumetric pulsed Doppler was 75 mL and the  regurgitant fraction was 49%.

Why the TTE-TEE discrepancy in color Doppler display of the MR jet?

Clue…

Clue

• The color flow Doppler over the LVOT, left atrium and proximal ascending aorta is barely detecting any flow by color at a good Nyquist of 50 cm/s!
• Either the blood velocity is too low (not the case) or COLOR GAIN is not optimized and is just TOO LOW.

To optimize color gain, gain is increased till enough clutter/color noise is seen, then gain is decreased gradually to have minimal clutter in the background, so that gain is maximized and optimal.   

A Case in Point…

Parasternal views of a patient with MR secondary to MV prolapse before (left) and after (right) color gain optimization.

Apical 4-chamber views of the same study before (left) and after (right) color gain optimization.

This case was an actual case whereby the interpreter realized that MR is severe by other measures, noticed that color gain was reduced (flows in the chambers were not well detected) and asked to repeat the study with more optimal color gain.

Confirmatory TEE shows severe MR secondary to bileaflet MV prolapse, involving the posterior leaflet more.

Key Points

• The intensity and extent of a color Doppler jet in MR depend, as discussed in the guideline, on the jet momentum affected by regurgitant orifice area, the driving pressure, left atrial compliance, and whether the jet impinges on the wall…
• However, color gain is also very important and can alter the interpretation of severity of regurgitation by color Doppler. There is no set dial for the gain to be appropriate (description for optimization as noted above and in the guideline).
• Therefore, a low color gain setting can decrease the severity assessment of a regurgitation. Conversely, if contrast echo is used, the jet will look much larger (regurgitation should not be interpreted when the chamber is enhanced with contrast).
• A critical eye is always essential. While most studies are performed with optimal color gain, there are instances where nobs are inadvertently manipulated that can alter these settings.
• Suspicion of a low color gain is more subtle than noticing a very high gain color (image color clutter is obvious).
• Low color gain is suspected, as shown in the cases, by the lack of flow visualization in areas where flow is usually seen with velocities above 30-40 cm/s or so. If the flow looks very “anemic”, be suspicious.

Return to Valvular Regurgitation Cases

Recommendations on the Echocardiographic Assessment on Non-Invasive Native Valvular Regurgitation (insert link when available)