Thomas et al developed the Mitral Regurgitation Index (MRI) to grade the severity of mitral regurgitation based on findings seen on Doppler echocardiography. The authors are from the University of California in San Francisco.
Parameters:
(1) jet penetration
(2) proximal isovelocity surface area (PISA)
(3) continuous wave (CW) jet intensity and character
(4) pulmonary artery pressure (PAP) in mm Hg
(5) pulmonary venous flow parameter
(6) left atrial size
|
Parameter |
Finding |
Points |
|---|---|---|
|
jet penetration |
no net |
0 |
|
|
central jet; jet does not impinge on lateral wall in any view |
1 |
|
|
eccentric jet which extends up to the first pulmonary vein |
2 |
|
|
eccentric jet that encircles the atrium and extends beyond the pulmonary vein |
3 |
|
PISA |
none |
0 |
|
|
< 0.5 cm |
1 |
|
|
0.5 - 1.0 cm |
2 |
|
|
> 1.0 cm |
3 |
|
CW jet intensity and character |
no jet |
0 |
|
|
incomplete jet envelope |
1 |
|
|
complete jet envelope with jet density 20 - 50% of inflow |
2 |
|
|
complete jet envelope with jet density 50 - 70% of inflow |
3 |
|
pulmonary artery pressure |
< 25 mm Hg |
0 |
|
|
25 - 30 mm Hg |
1 |
|
|
31 - 45 mm Hg |
2 |
|
|
> 45 mm Hg |
3 |
|
pulmonary venous flow pattern |
systolic dominant flow (systolic impulse exceeds diastolic by >= 50%) |
0 |
|
|
systolic dominant flow (systolic impulse exceeds diastolic by < 50%) |
1 |
|
|
diastolic dominant flow |
2 |
|
|
systolic flow reversal |
3 |
|
left atrial size |
normal |
0 |
|
|
mild enlargement |
1 |
|
|
mild to moderate enlargement |
2 |
|
|
moderate enlargement |
2 |
|
|
moderate to severe enlargement |
3 |
|
|
severe enlargement |
3 |
where:
• PISA is termed a surface area yet units are in centimeters. In the text the authors discuss the PISA radius as the distance from the first alias to a point at the trailing edge of the mitral leaflets nearest the regurgitant orifice along a vector parallel to the direction of the interrogation at a point in midsystole (WHEW!, page 2017).
• Pulmonary artery pressure = (tricuspid regurgitant gradient) + (right atrial pressure) according to the appendix (page 2021).
• The pulmonary venous flow pattern was obtained from the Doppler interrogation of the right upper pulmonary vein (page 2018).
total score =
= SUM(points for all 6 parameters)
mitral regurgitation index =
= (total score) / (number of parameters summated)
Interpretation:
• minimum MRI: 0
• maximum MRI: 3
• The higher the MRI the more severe the valvular regurgitation.
Purpose: To evaluate a patient with mitral regurgitation using Doppler echocardiography and the Mitral Regurgitation Index of Thomas et al.
Specialty: Cardiology
Objective: imaging studies, severity, prognosis, stage
ICD-10: I05,
