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 being 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, 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
Please note: iheartecho.com is not endorsed by or affiliated with the American Society of Echocardiography
I can even remember one day when I had seven patients in a row with moderate to severe aortic stenosis. It can certainly be frustrating and time consuming for inexperienced sonographers to have to take additional images and to add on to our study time. Even experienced sonographers must sometimes take a step back and to remember that these patients need that extra time and attention to further the clinical decision making process for the treating physician and to bring answers and solutions to our patients. We are all human and it is easy to look at our schedules and our busy lives and get frustrated when something throws off our plans. However, treating every patient as though they are our own mothers, our fathers and our friends, will help to put our scanning protocols and requirements in the right perspective. This is the reason we do what we do.... patient care. Above all else, our imaging techniques, protocols and scanning skills should be sharpened and enhanced to further benefit the patients we serve.
Aortic stenosis is very common in populations over 65 years old and progression of the disease from sclerosis to critical stenosis can take less than 5 years. If you scan in an accredited lab, there may be many more additional protocol images to add when assessing aortic stenosis. However, with a few tips and tricks even a very new sonographer can master the art of imaging aortic stenosis and save the frustration of this very common pathology. This is the core of what we do, which is why this is included as a case study requirement for adult echocardiography accreditation through the Intersocietal Accreditation Commission.
So let's start with the basics... knowing the anatomy of the valve is important when using descriptions of aortic disease. The valve is comprised of three leaflets:
• right coronary cusp
• left coronary cusp
• non-coronary cusp
Another core basic item in evaluation aortic stenosis is the Continuity Equation. Having an understanding of the hemodynamics is really the basis for an understanding of the disease process and echo evaluation of aortic stenosis. The Continuity Equation in it's most basic explanation is conservation of mass.... what goes in MUST come out.
Also, due to the fact that the continuity equation squares the LVOT diameter, this can significantly introduce errors into the equation if that value is only slightly off or mis-measured. It is critical that the sonographer measure the LVOT very carefully and with attention to detail. According to the American Society of Echocardiography the LVOT (aortic annulus) should be measured with the following parameters and considerations:
•Inner edge to inner edge convention
•Mid-Systole with aortic valve leaflets open
•At the aortic valve leaflet hinges (typical placement)
•Perpendicular to the axis of flow
Doppler angle and sample placement. What more can I say? This is critical to the mathematics. It is important to place the LVOT Doppler sample at approximately the same location as the LVOT diameter is measured from. The LVOT Doppler waveform should also not show significant valve clicks, otherwise Doppler sample placement is too far into the aortic valve.
It's important to ensure correct angle THROUGH the aortic valve orifice. In reviewing countless numbers of echo cases through the years for accreditation and quality review, I've seen many aortic valves evaluated incorrectly.
It is important to place your continuous wave Doppler sample THROUGH the valve orifice and NOT across the valve leaflets. Simple hand maneuvers and tilting the transducer can open up the LVOT and allow for correct Doppler angle through the valve.
Now that you have the basics down, there are few extra steps we can do to evaluate aortic stenosis. Protocols should always include evaluation from the suprasternal notch view, and also evaluation with the Pedoff/dedicated continuous wave transducer. Additional Doppler attempts can also be performed in the subcostal view and the high right parasternal view (always ensuring that true valve clicks are obtained on continuous wave Doppler as this ensures the angle is positioned through the valve orifice).
While the pedoff transducer might be scary for some newer sonographers, once you get the hang of it, you'll realize it's really very simple. For the apical approach, start by beginning where you were able to obtain the best apical window of the aortic valve and LVOT. While observing the CW spectral display, listen to the blood flow and isolate one of the typical valve waveform patterns of either the mitral, aortic or tricuspid valves. Remember the aortic valve is in between the two atrioventricular valves so, keep that in mind when adjusting the probe. Also, SLOW DOWN - use very slow adjustments when optimizing the transducer waveforms and trying to bring in the aortic valve.
When using the suprasternal notch approach, have the patient extend their neck and try to visualize the position of the ascending aorta and direct the face of the probe at a steep downward angle. One important thing to remember is that because there are no images, you must annotate the location on your images. This is required for accreditation and also just a good practice.
Let's not forget that high right parasternal view! The best patient positioning for this is right lateral decubitus. The patients' arm should be positioned up and out of the way.
Often it is helpful to find this view with 2D imaging and assess the valve both with the imaging and non-imaging transducers. I suggest that you practice the Pedoff transducer and additional windows on normal patients and practice often when first beginning your echo career...
practice makes perfect! Before you know it, you'll be an AS pro!
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