Right Ventricular Evaluation

The right ventricle is crescent shape that wraps along the LV. This adds complexity to the quantification of its size and function

Our focus here on cardiac ultrasound is to be able to determine RV size and function in a qualitative or semiquantitative way in an interrogation that is conducted without the requirement of performing specific measurements. We will explore some qualitative appreciation of sizes and function of the RV and go beyond the scope of FoCUS to be give you numerical data you can use clinically. 

1. Visual Global Assessment

Comparing right ventricular dimensions to left ventricle dimensions is an important technique to assess function. The ideal views for this technique are apical 4-chamber and subcostal 4-chamber views. The RV internal diameter should not be more than 2/3 the size of the LV, and it should not extend more than 2/3 to the apex of the LV. Changes in the size of the RV as well as displacement of the tricuspid valve can be used to evaluate function. Linear measurements are very useful to determine function (see later section)

 

Normal RV Dimensions and Function

-RV internal diameter should be <2/3 of the size of the LV

-RV should extend <2/3 to the apex of the LV

-The interventricular septum should not be flattened or D shaped which is indicative of RV pressure or volume overload

-The Systolic eccentricity index (EI) is a  measure of RV overload. At end systole D1 bisects pap muscles and D2 is orthogonal. EI is D2/D1. Normal EI is 1 and dyskinesia is present when EI>1

D2

D1

 

Dilated and

Depressed RV

On these clips: 

-Enlarged RV. The RV is bigger in size than the LV

-Depressed RV

-On diastole the septum is pushed towards the LV indicating fluid overload.

-Enlarged RA

Dilated and

Depressed RV

-Enlarged RV. The RV is bigger in size than the LV

-Depressed RV

-On systole and diastole the septum is pushed towards the LV indicating fluid and pressure overload.

-Enlarged RA

 
 

Dilated and

Depressed RV

-Enlarged RV. The RV is bigger in size than the LV

-On systole and diastole the septum is pushed towards the LV indicating fluid and pressure overload. More evident on diastole.

-Enlarged RA

-TAPSE <17mm (see below)

Comparison of RV Depression

-On the left the RV diameter does not appear enlarged and function seems mildly depressed.

-On the right, the RV is enlarged and depressed with both fluid and pressure overload. The free wall of the RV does not appear to move but the apex does (McConnell's sign)

 
 

2. Linear Dimensions of Size. Beyond FoCUS

Measurements by 2D ultrasound  are challenging because of the complex geometry of the right ventricle and the lack of specific right-sided anatomic landmarks to be used as reference points. The apical four chamber view results in considerable variability in how the right heart is sampled. RV linear dimensions derived from these areas may vary widely in the same patient with relatively minor rotations in transducer position. RV measurements may also be limited when the RV free wall is not well defined because of the dimension of the ventricle itself or its position behind the sternum. In general, a diameter >41 mm at the base and >35 mm at the mid level in the apical 4 chamber view will indicate RV dilatation. 

<41
<35
<35
<35

Linear dimension of the RV. The images above display the maximum measurements considered normal (in mm). Solid line, mid right ventricular diameter, solid red line is at the base of the RV. 

Basal RV dimensions on the left image is the maximum dimensions obtained at the base of the RV inflow (red line). The mid cavitary RV linear dimensions taken at mid pap level with the white line. Both measurements on diastole. On the middle and right image the white dotted line is the proximal RV outflow diameter; taken from the anterior RV wall to the interventricular septal-aortic junction(right image) or the aortic valve (center image). Upper limit of normal displayed on images (measurements in mm).

Nml Subcostal_edited.jpg
<50

On the left, a 4 chamber subcostal view. Linear thickness of the RV free wall and end diastole with pap muscles excluded. Upper limit of normal (in mm) displayed on the image.

3A. Fractional Area Change RV

3. Linear Dimensions to Estimate RV EF. Beyond FoCUS

There are multiple numeric parameters to evaluate RV function. We will take a look at the easiest to perform.

FAC provides an estimate of global RV systolic function. The apex and free wall must be included in the measurement. RV FAC < 35% indicates RV systolic dysfunction. In the images below, from left to right end diastole and systole.