Making Waves - All About Ultrasound BloG
Diastology can often be confusing, as there have many updates to the standards and guidelines regarding how to assess and grade left ventricular diastology in the past few years. So let's dig in to how to assess this and the echocardiographer's role in evaluating diastology based on the updated
2016 ASE Guidelines.
So as cardiac sonographers, we should all know the basics... E/A reversal = Diastolic Dysfunction, but there is a little more to it than that. If you're not fully evaluating diastology with additional measures, you're probably missing some positive cases. Also the Intersocietal Accreditation Commission now includes reporting of left ventricular diastolic function as a requirement for echocardiography accreditation.
What exactly is diastolic dysfunction? This is a decrease in left ventricular compliance during diastole. While the ejection fraction and left ventricular systolic function are needless to say, pretty important, the diastolic function of the heart is important too. If the heart does not rest properly during diastole, then it cannot fill with the right amount of blood volume needed and eventually this can lead to heart failure and significant clinical implications. So it's important to know the left atrial pressures and end diastolic left ventricular pressures in order to determine the level of severity of the diastolic dysfunction. The updated guidelines break it down like this:
Grade 0 = Normal
Grade 1 = Impaired Relaxation/Diastolic Dysfunction
Grade 2 = Pseudonormalization
Grade 3 = Restrictive Pathophysiology
So how do we get to the diagnosis? Based on the updated standards from the ASE, determination of normal vs diastolic dysfunction is evaluated initially, based on the patient's EF.
If a patient has a normal ejection fraction then the algorithm looks at four components to determine whether or not the patient has a degree of diastolic dysfunction:
1. Average E/e’ > 14
2. e' velocity
-Septal e’ velocity < 7 cm/s
-Lateral e’ velocity <10 cm/s
3.TR velocity > 2.8 m/s
4. LA volume index >34ml/m2
If <50% are positive, the patient is considered normal. If >50% are positive, the patient has a degree of diastolic dysfunction. If only 50% are positive, then we are unable to determine whether the patient has diastolic dysfunction.
If the patient has a compromised ejection fraction, then we can assume that there is a degree of diastolic dysfunction and can grade it based on the E/A ratio.
When the mitral inflow pattern shows an E/A ratio <0.8 along with a peak E velocity of <50cm/sec, then the mean LAP is either normal or low and this is considered a Grade 1.
When the mitral inflow pattern shows an E/A ratio of >2, the mean LAP is elevated, consistent with Grade 3 diastolic dysfunction. Keep in mind patients with young or athletic patients may show this ratio in the setting of normal diastolic function. Also, patients in atrial fibrillation may exhibit a reduced or loss of the mitral A wave and may also produce similar findings.
For patients with reduced EF's that do not meet one of those parameters and the mitral inflow shows an E/A Ratio >0.8 AND the peak E velocity is >50 cm/sec OR E/A Ratio >8 but <2, then other parameters are required for determination of diastolic dysfunction.
1. Average E/e’ Ratio - average E/e’ ratio >14
2. TR Velocity - peak jet velocity >2.8 m/sec
3. LA Volume Index - >34 mL/m2
If 2 of 3 are negative, the patient is considered to have Grade 1 diastolic dysfunction, where if 2 of 3 are positive, then this is considered Grade 2.
So, are you confused yet? Let's look at the grading parameters a little closer.
GRADE 0 - NORMAL DIASTOLOGY
This means that left atrial pressures (LAP) are normal and the diastolic function is not impaired. The left ventricle relaxes normally throughout diastole and allows for complete diastolic filling. The E/A ratio in a normal setting, is between 1 and 2. This gradually reduces with age and E/A ratio >0.75 may be considered normal above 75 years.
GRADE 1 - IMPAIRED RELAXATION/DIASTOLIC DYSFUNCTION
Patients that do not have a NORMAL EF, will have a degree of diastolic dysfunction and are evaluated based on filling pressures of the left atrium. Left atrial pressures can be somewhat normal in a patient with Grade 1 diastolic dysfunction, but will increased as this progresses. Patients with Grade 1 diastolic dysfunction will have reduced e' velocities and prolonged deceleration time.
GRADE 2 - PSEUDONORMALIZATION
One of the biggest factors that our role as sonographers requires, is knowing your patient history. This will often help you know whether or not you're dealing with a normal waveform or pseudonormalization. Granted there are some other key factors but the most obvious is whether or not the patient has previously been diagnosed with diastolic dysfunction. If they have previously had reversal of the E/A waveform and now have a normal waveform pattern, this is a pretty good indicator that the patient is in pseudonormalization. Also, keep in mind some of the other factors associated with increased left atrial pressures, such as blunting or changes to the pulmonary venous waveform, as well as reduced e' velocities. When pseudonormalization is present, the valsalva maneuver can assist to "unload" the ventricle and to reduce filling pressures, causing the E/A reversal to be unmasked.
GRADE 3 - RESTRICTIVE FILLING PATTERN
Grade 3 diastolic dysfunction involves increased left atrial pressures and increased end diastolic left ventricular pressure. This may result in reversal of the pulmonary venous waveform and is often seen with the presence of left atrial enlargement and left ventricular hypertrophy.
ECHO DIASTOLOGY GRADING ANALYSIS TOOLS!
The newly updated algorithm for determining diastology and left atrial pressures can be a little overwhelming and difficult to follow, but we make it easy with our Echocardiography Analysis Tools which include our exclusive LV Diastology Assessment Tool! Quickly and easily determine and grade the diastology based on the updated ASE guidelines. Also there are many other parameters that affect diastology and the application of the diagnostic criteria, such as age, athletic hearts and other factors. Learn and review these additional factors and an in depth study of diastolic dysfunction in our MASTERING LV DIASTOLOGY CME COURSE!
REFERENCE: ASE/EACVI GUIDELINES AND STANDARDS Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography: An Update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging; Nagueh et al
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