Mitral Regurgitation


	Definition: Severe organic MR: Regurgitant volume >= 60 ml, or Effective Regurgitant Orifice (ERO) >= 40 mm2 or 0.40 cm2. But, in functional or ischemic MR, severe regurgitant volume is ERO >= 20 mm2 or 0.20 cm2. (Heart 88 (Suppl IV:1v1 - 1v4, 2002)
	MR jet area as percentage of LA area: <20% Mild MR; 20-40% Moderate MR; >40% Severe MR. This analysis is marred by jets hugging walls (Coanda effect) and instrument settings, transducer position, LA pressure, LA compliance, LV pressure and LVEF. Unlike an LV gram, the color MR jet is a velocity map whose exent reflects the velocity of MR flow at any moment rather than the absolute regurgitant volume at that point in time.


	Calculate Effective Regurgitant Orifice Area
	Mitral Annulus Diameter (cm) =	VTI Mitral Regurgitation by CW Doppler (cm) =

	LVOT Diameter (cm) =	Mitral Regurgitant Volume (cc) =

	Mitral Annulus VTI (cm) =	Regurgitant Fraction =

	LVOT VTI (cm) =	Effective Regurgitant Orifice Area (cm2) =


	Calculate Effective Regurgitant Orifice Area - PISA
	PISA Radius (cm) =	VTI Mitral Regurgitation (cm) =

	Color Flow Velocity - PISA (cm/sec) =	Mitral Regurgitant Volume (cc) =

	MR Orifice Velocity by CW (cm/sec) =	Effective Regurgitant Orifice Area (cm2) =


� To trigger calculations, press TAB.

A Barebones Guide To PISA

Proximal Isovelocity Surface Area (PISA) is the name given to a region of flow that develops as a flowing liquid flows through a hole. As the flowing liquid approaches the hole, the relationship between pressure and the size of the hole causes the liquid to accelerate. This leads to production of a succession of laminar �shells� of velocity in the liquid.

Suppose that ping pong balls came in 4 sizes, and that you had one of each size. Now suppose that you cut each ping pong ball in half, and discarded one half of each ball. If you then stacked the halves so that the smallest ball�s half was on the bottom (face down) and the next smallest ball was placed face down over it, and then the remaining two balls were placed in the same fashion, you would have a PISA array.

Each of the �half ping pong balls� in this PISA array would represent a flow velocity shell. Of course, as the liquid gets closer to the hole, it flows faster. A PISA shell is larger in more severe mitral regurgitation and smaller in less severe mitral regurgitation.

By using ColorFlow Doppler ultrasound, it is possible to identify each of these shells of flow on the ventricular side of a mitral valve showing regurgitation. This identification process is carried out by adjusting the ColorFlow scale factor. The lower the scale factor (i.e., the slower the velocity), the larger the PISA. Here�s the schematic:

This is the first step. The next step is to determine the ColorFlow Doppler characteristics of the mitral regurgitant jet. Once the jet is imaged, its peak velocity is recorded then the jet is traced to measure its Velocity Time Integral (VTI). Here�s the schematic for this step:

At this point, it is possible to calculate the Effective Regurgitant Orifice (ERO) and the Regurgitant Volume (RV).

Here are two sample cases:

Case 1. A patient with severe mitral regurgitation.

Nyquist Velocity for the shell (Vr) = 38 cm/sec

Proximal convergence region radius (r ) = 1.56 cm

Mitral Regurgitation jet Vmax = 466 cm/sec

Mitral Regurgitation jet VTI = 123.2 cm

Calculated Effective Regurgitant Orifice (ERO) = 1.25 cm2

Calculated Regurgitant Volume (RV) = 154 cc

Case 2. A patient with mild-moderate mitral regurgitation.

Nyquist Velocity for the shell (Vr) = 19 cm/sec

Proximal convergence region radius (r ) = 0.68 cm

Mitral Regurgitation jet Vmax = 475 cm/sec

Mitral Regurgitation jet VTI = 134.8 cm

Calculated Effective Regurgitant Orifice (ERO) = 0.12 cm2

Calculated Regurgitant Volume (RV) = 15.8 cc

It must be remembered that PISA can vary during different parts of ventricular systole, and this leads to potential variability in the measurement.

Source: Chan KT et al: Comparison of Severity of Mitral Regurgitaion by Angiography and PISA Method by Echocardiography. J HK Coll Cardiol 4:2-7, 1996.

Mitral Regurgitation: Other Guidelines and Recommendations

Trivial or mild MR can be seen in 20-40% of subjects with structurally normal hearts. Heart 88(SupIV):iv11.

Severe MR will tend to produce a high intensity Doppler envelope, mild MR will be fainter. Beam alignment is critical for this relationship to be manifested, though.

Please click on the �Quantitative Doppler Methods� button above for vena contracta and other standards.

The AHA/ACC recommend valve surgery in those patients with severe MR and an LV end systolic diameter of 4.5 cm or greater even if the patient is asymptomatic. The onset of pulmonary hypertension is an ominous sign in the setting of MR, and its early detection is mandatory.

Exercise evaluation is frequently helpful in those who are apparently symptomatic with �non-severe� MR by resting echocardiogram. Pre- and post-exercise EROA determination can be helpful.