Diastolic dysfunction as concept has come a long way after initial hiccups . Now, it is a well established left ventricular pathology , and has a sound physiological and molecular basis. Even though there are variety of methods available to quantify LV diastolic function, echocardiogram is the simple method to identify and grade diastolic dysfunction.
There are 4 grades of diastolic dysfunction
1.Impaired relaxation (without elevated filling pressure)
Some describe another grade 1 a with elevated filling pressure
2.Pseudonormal mitral inflow
What is pseudo normal pattern ?
The grade 1 is the most common type diagnosed . It is diagnosed when the A velocity is more than E velocity . This simply implies , ventricular filling needs greater assistance from atrial contraction than in resting conditions. It is so common , especially in elderly , many thought it should not be considered a pathology . In youngsters it is definitely pathological especially if it is persistent.
The issue that really concerns us is this : When the diastolic dysfunction progress from grade 1 to grade 2 , the mitral the inflow doppler pattern , instead of showing any new changes simply nullifies the changes that occurred in grade 1 and records a normal E : A velocity .
So , a person with grade 2 diastolic dysfunction will have a near normal pattern .Of course deceleration time, and IVRT is shorter than in grade 1 but it is not very useful in differentiating it from normal .
Pseduonormal is actually equivalent to moderate diastolic dysfunction , but the abnormality is masked as near normal filling is restored with atrial assistance . So, technically it a assisted LV filling . A superficial look at the doppler pattern may exactly mimic normal . But there will be a 2 D echo abnormality that makes the patient pathological . Our eyes need to look beyond doppler ( in coherence with 2 D ) to differentiating normal or pseudo normal.
It is learnt , 2D abnormality of LV or LA occurs in nearly 90 % of grade 2 diastolic dysfunction .(There can be a pure functional grade 2 diastolic dysfunction without structural changes in LA/LVH in minority -This is poorly understood form of silent sub clinical CAD manifesting only as diastolic dysfunction )
Traditionally there are few methods taught in echocardiaographic schools all over the world to differentiate normal from pseudonormal
1.Pulmonary vein doppler
2.Response to valsalva maneuver
3.Tissue doppler etc
One simple echo feature that is often forgotten , that can be really useful in differentiation of normal from pseudo normal is left atrial dimension
While patient with pseudonormal who have progressed into stage 2 will show a definite left atrial abnormality .
When does a left atrium begins to enlarge in diastolic dysfunction?
- It depends on LA thickness and LA afterload (LVEDP is the afterload for LA)
- It is generally believed LAE will be there in almost all cases of grade 3 diastolic dysfunction.
- It is present in majority of patients with grade 2 as well . But the degree of LAE may be less ( 4-4.5cm)
It is yet unclear , the onset of LA enlargement in diastolic dysfunction .This is potentially a research topic for the fellows !
It is not uncommon to find LA enlarge like a balloon even in stage 2 of diastolic dysfunction. So , in patients who are suspected to have pseduonormal doppler profile , look for the presence of LAE , (however mild it may be !) , there is no business for LA to enlarge in normal persons.
Ofcourse , if you are a echo expert one can measure A reversal in PV doppler, tissue doppler echo etc .But remember a simple 2D echo feature like a LA dimension / LVH may score over the sophisticated (Also read complex . . .) parameters in the grading of diastolic dysfunction
While we immerse ourself in sophisticated doppler methods to differentiate normal from psedunormal pattern, the fact that , normal persons will have normal hearts is often forgotten , and presence of left atrial enlargement (Which is all too common in pseudonormal !) straightaway settles the issue . Detailed diastolic function studies are warrented only if the LA size is normal .
*Correction: in table A reversal in normal is less than 35cm/sec