Throughout the history of echocardiography Right ventricular functional assessment has received less attention and suffered a step motherly concern. There are innumerable parameters to assess LV function , but we have very few for RV !
LV ejection fraction continue to reign supreme in spite of the inaccuracies and fallacies.RV ejection fraction by echo , never got into the main stream cardiology literature as a tool for RV function assessment.
(The major reason for this is , lack of a “mathematical shape” for RV !)
RV is formed by , a horizontal inflow , an elongated and wedged apex ,( in)conspicuous body and an ubiquitous RV outflow .No one really knows , how much these parts contribute individually to the conductive and contractile function of the low pressure venous ventricle.
(Of course, MRI and radionuclide derived RV EF can be accurate but doing these tests solely to measure RV EF defies clinical sense !)
In this scenario,
Two parameter can be considered simple and accurate to estimate the RV function.
Tricuspid annular displacement (TAD)
This is a simple m-mode derived parameter ( much ridiculed by modern day echo-cardiographer !)
M-mode echo in apical 4 chamber view across lateral tricuspid annulus .
- Normal displacement >2 cm
- RV dysfunction < 1.5cm
- Borderline RVD between 1.5 to 1.75 cm
The other parameter to measure tricuspid motion is
Tricuspid Annulus peak Systolic velocity (TAPSV)*
- This , in-fact linearly correlate with TAD.
- Normal TAPSV is > 10cm/sec
- Anything less than 8cm/sec is usually associated with RV dysfunction.
* One need not be depressed if tissue Doppler is not availablein their echo machine , TVD by M mode is good enough in most situations.
Situations where RV function is impaired include
- Severe forms of dilated cardiomyopathy.
- Primary (or secondary ) pulmonary hypertension
- RV infarction
- COPD -terminal stages
- RV dysfunction with VVI pacing
- Following CRT
It is often said there will always be a simple solution for any complex problem . But, it is recognised late.
In our quest for ideal RV functional parameter , we were entangled in the complexities for decades , only to realise an obscure M -mode parameter in apical 4 chamber , could be an accurate way to exclude significant RV dysfunction.