Diastolic Dysfunction for Perioperative Transesophageal Echocardiography

Patients presenting for cardiac surgery rarely present with normal hearts and often have some degree of diastolic dysfunction. Diastolic dysfunction is a mechanical cardiac abnormality that we can measure and quantify with echocardiography.

Diastolic heart failure is diastolic dysfunction with high morbidity and a high readmission rate. Possible causes of diastolic dysfunction can be caused by structural heart diseases (hypertrophy, constriction, fibrosis) or functional heart disease (ischemia). Valvular abnormalities and ventricular abnormalities are often precursors to diastolic dysfunction. Your patients experience this clinically at elevated filling pressures, pulmonary congestion, and SOB. The prevalence of diastolic dysfunction is as high as 25% of the adult population over 40 years of age!

Mathew’s Clinical Manual and Review of Transesophageal Echocardiography does a great job explaining this topic and references a couple of papers that suggest that patients with diastolic dysfunction that present for cardiac surgery are prone to:

• Perioperative hemodynamic instability
• Potentially worse cardiac outcomes,
• An increased risk for decompensation in the peri-operative period.

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Basic Diastolic Physiology

Clinically, diastole begins with closure of the aortic valve and ends with mitral valve closure.

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The Four Phases of Diastole:

1. Isovolumic relaxation (IVRT): begins with AV closure. The LV pressure declines rapidly during this period until the left ventricular pressure falls below the LAP leading to the mitral valve’s opening. There is no blood movement or other interfering factors.
2. Rapid filling phase: starts with MV opening when the LAP exceeds the LV pressure and ends with equalization of pressure between the LA and LV. In normal hearts, this phase makes up 80% of ventricular filling. This the E-wave velocity on the transmitral Doppler
3. Diastasis: mostly passive filling, little change. When the LAP equals the LV pressure, there is no flow across the MV.
4. Atrial Contraction: the final phase of diastole contributes about 20% of ventricular filling in normal hearts. During this final filling, the LAP exceeds the LVP to complete the LV preload. The actual contribution depends on ventricular compliance, intrinsic atrial contractility, and ventricular pressure. In atrial fibrillation, this A-wave velocity is absent on transmitral Doppler.

My 1st #AI-guided echocardiography today (fun & by democratizing acquisition it will change the field)
What does that mean?
You put the transducer on the patient’s chest ->the AI tells you how to properly position it and then automatically captures video images when spot on. pic.twitter.com/t3DaE32ftg

— Eric Topol (@EricTopol) January 29, 2020

The Echocardiographic Parameters of Diastolic Dysfunction

Before you can measure and quantify diastolic dysfunction. You need to understand the tools used to quantify the degree of diastolic dysfunction. There are several echocardiographic parameters available to help you quantify diastolic dysfunction, but we will only present the parameters used in the guidelines. They are:

1. Trans-Mitral Inflow Doppler Velocities
2. Mitral Annular Velocity with Tissue Doppler
3. Left Atrial Volume Index
4. Tricuspid Regurgitation Velocity
5. Pulmonary Vein Flow

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Trans-mitral Inflow Doppler Velocities

This parameter is not used to evaluate diastolic function in patients with normal LV function, however, the trans-mitral inflow Doppler velocity is usually sufficient to identify patients with increased LAP in the setting of reduced EF.

• Trans-mitral inflow velocities are best obtained from either the ME 4-Chamber View or the ME LAX View.
• Position the Doppler sample volume (1-3mm) between the mitral leaflet tips. The shape of the trace changes as you move your sample volume from the mitral annulus to the leaflet tips.
• As with any other pulsed-wave Doppler trace, adjust your baseline and size to maximize the trace.
• Measure the Peak E-wave and A-wave velocities from baseline.
• Measure the Deceleration time (DT) from the Peak E-wave velocity back to the baseline.
• The metric very preload dependent, reflecting the LA to LV pressure gradient

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Mitral Annular Velocity with Tissue Doppler

The utilty of tissue Doppler has increased.

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Tricuspid Regurgitation Velocity

Until the recent update this was a parameter that I had measured routinely to help calculate PASPs but I did not use it in the context of evaluating LV filling pressures.

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Left Atrial Volume Index

This parameter is mostly not useful for the cardiac anesthesiologist performing TEE. Its a parameter that is best saved for surface echocardiography.

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Pulmonary Vein Flow

Pulmonary vein flow was used more prominently before the most recent updates. It has become more of a secondary measure with increased use of tissue doppler and mitral annular velocities.

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Diastolic Function Graded by Echocardiography

Evaluating Diastolic Dysfunction vs Assessment of Elevated Filling Pressures

Before evaluating diastolic function it is important to differentiate between patients with normal left ventricular EF and reduced left ventricular EF or a form of structural heart disease. Depending on which group your patient falls into, the focus is a different one (existence of diastolic dysfunction vs. estimation of filling pressures).

The most recent ASE/EACVI Guidelines for evaluating diastolic dysfunction (found here), have attempted to simplify the evaluation process for diastolic dysfunction to make it more useful in daily clinical practice.

In doing so they state:

With respect to the grading of LV diastolic dysfunction, it is the recommendation of the writing group to determine the grade of diastolic function based on the presence or absence of elevated LV filling pressures as a first step.

ASE/EACVI Guidelines 2016 – Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography

However, that statement is a little misleading. The algorithm for the echocardiographic assessment of LV filling pressures as a first step is only present if your patient has a reduced LV systolic function.

Keeping that in mind, here is how I use the guidelines in clinical practice.

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Grades of Diastolic Dysfunction:

Before we get to far into the algorithms, its important to understand how we grade and evaluate diastolic dysfunction.

• Normal diastolic function implies no diastolic function is present. The ventricle relaxes very well.
• Grade I Diastolic dysfunction / Impaired relaxation is the first stage of diastolic dysfunction. Decreased suction of the LV
• Grade II Diastolic dysfunction / pseudonormalization is the second state of diastolic dysfunction. It corresponds with Increased stiffness of the LV, elevated LAP.
• Grade III diastolic dysfunction / restrictive filling (reversible) is a later stage of diastolic dysfunction. Characterized by High LAP, noncompliant LV. May be reversible with reduction of preload (e.g., diuretics).
• Grade IV diastolic dysfunction / restrictive filling (irreversible) is the end stage of diastolic dysfunction—the same grade III features but with no benefit from a reduction of preload.

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Grading Diastolic Function with Normal LV Systolic Function:

Patients with normal hearts don’t have diastolic dysfunction. However, there are lots of patients with normal LV systolic function and coexisting diastolic dysfunction. Your job in the OR is to determine if that normal ventricle has coexisting diastolic dysfunction or is a truly normal ventricle.

This evaluation is tricky because of the overlap between Doppler values in normal healthy hearts and those with normal LV systolic function and coexisting diastolic dysfunction.

Note: Age is an important factor. The slowing of LV relaxation may lead to increased LV stiffness and LV filling patterns in the elderly that resemble mild diastolic dysfunction in a younger patient.

For a patient with normal LV function the four parameters used to evaluate diastolic dysfunction are:

1. Mitral annular e’ velocity ( septal e’ <7 cm/sec, lateral e’ <10 cm/sec )
2. Average E / e’ ratio > 14
3. Peak TR velocity > 2.8 m / sec
4. LA maximum volume index > 34 mL / m2

LV diastolic function is normal in a patient with normal EF if more variables do not meet the criteria for abnormal function. Said another way, 3/4 in either direction is yes or no.

IF you have 2/4 positive, the study is inconclusive, bummer.

Key Points:

• Use your patient history/ultrasound to decide if your patient has a normal LV systolic function or not to guide which pathway you want to use.
• For Normal LV Systolic Function, 3/4 in either direction rules diastolic dysfunction in or out.
• IF 2/4 are positive, you are stuck with an inconclusive study.

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Grading Diastolic Dysfunction with Reduced LV Systolic Function:

If the LV systolic function is reduced, the main reason for evaluating diastolic function is to estimate the LV filling pressures. When estimating filling pressures, the LAP is the pressure that better correlates with the patients’ pulmonary congestion symptoms. (Remember, we are here for the patients)

The biggest difference in the two approaches and parameters is for patients with reduced EFs, Your evaluation of LV filling pressures begins with the transmitral inflow veloicties.

NOTE: this approach assumes no atrial fibrillation, no significant mitral valvular disease (less than moderate), no mitral valve repair, no left bundle branch block, no ventricular paced rhythm, and no LV assist devices. This is a large number of the patients we see in the operating rooms!

The Parameters used to evaluate elevated filling pressures and diastolic dysfunction are:

1. Mitral inflow patterns
2. TR jet peak velocity
3. E / e’ ratio
4. LA maximal volume index (not on TEE)

Key Points:

• If your patient has a reduced LV systolic function, the transmitral inflow patterns are often enough to identify patients with increased filling pressures.
• The decelleration time (DT) of the transmitral E-wave velocity is an important predictor of clinical outcome.

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Grading Diastolic Dysfunction with Mitral Regurgitation

Grading Diastolic Dysfunction with Mitral Regurgitation

Grading Diastolic Dysfunction with Mitral Regurgitation

Grading Diastolic Dysfunction with Mitral Regurgitation

Grading Diastolic Dysfunction with Mitral Regurgitation

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How to Grade Diastolic Dysfunction in Four Easy Steps

Step 1: Use the patient history to guide your exam and parameters for evaluation

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Step 2: Doppler Examination of the transmitral infow velocities.

Key Points:

• Use pulse wave doppler with 1-3 mm sample volume in the ME 4-chamber or ME LAX view for range specificity
• Position your sample volume between the leaflet tips, not the annulus. As you move further away from the annulus the velocities increase. (** INSERT IMAGE )
• Adjust the baseline and scale to allow the spectral trace to fill the measurement space.
• Measure the peak E and A wave velocities and the deceleration time (DT) from E-wave peak velocity to baseline.
• This trace reflects the LA to LV pressure gradient and LV filling across the MV

Your Ideal Image:

Caveats for Use:

• Trace is affected by changes in relaxation and compliance
• Unreliable in normal systolic function
• Very preload dependent, a decrease in preload will decrease E-wave and Increase DT
• Rhythm and conduction dependent, increased HR, paced rhythms have fused E and A waves
• Not used in the diastolic assessment in a-fib, MV disease, LVADs, LBBB or Ventricular paced patients.

Transmitral parameter:	Normal Values:
Peak early velocity (E wave)	50-80 cm / s
Peak late velocity (A wave)	30-50 cm / s
E / A ratio	1-2 : 1
Deceleration Time (DT)	140 – 240 ms
Isovolumic relaxation time (IVRT)	60-90 ms

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Estimating LV filling pressure in specific diseases

Earlier we discused all the exclusions for the traditional algorithm. Here we will adress how to evaluate diastolic dysfunction in the presecenct of specific cardiovascular diseases.

Final Thoughts

There are multiple parameters that can be used to evaluate diastolic dysfunction. However there are key points to rememeber when using these parameters:

• The is often overlap between doppler values in patients with diastolic dysfunction and normal diastolic function
• There is no silver bullet, you have to use all your parameters before making a diagnosis
• When you use multiple parameters, not all of them will agree. The more the parameters agree, the more confidence you can have in your diagnosis.
• Like many echocardiographic-derived parameters, they are dependent on the patient’s clinical condition. They will vary depending on preload, afterload, heart rate, and rhythm.