Diastolic Function: Normal vs Abnormal

Normal vs Abnormal Diastolic Function

• Normal function: The heart fills to a normal end-diastolic volume without increasing end-diastolic filling pressure, both at rest and with exertion.
• Abnormal function: The heart is unable to fill to the normal volume needed for an adequate stroke volume without an abnormal increase in filling pressures.

Components of Diastolic Function

• Two main components of left ventricle function:
  • Active myocardial relaxation
  • Passive chamber compliance/stiffness

Active Relaxation

• Energy-dependent process in early diastole.
• Involves early, rapid filling and a decrease in left ventricle (LV) pressure.
• Faster decrease correlates to better relaxation (younger hearts), slower decrease indicates impaired relaxation (occurs with age).

Passive Compliance/Stiffness

• Refers to how readily the left ventricle accepts blood flow.
• Occurs during filling (early filling, diastasis, and atrial contraction)
• A compliant ventricle allows blood flow without a significant pressure increase ("sucks blood in").
• A stiff ventricle demands a larger increase in pressure to increase ventricular volume ("pushes blood in").

Key Points about Diastolic Function

• Myocardial relaxation is often abnormal in patients with diastolic dysfunction.
• Myocardial stiffness (non-compliance) results in increased filling pressures.
• Echocardiography measures myocardial relaxation and filling pressure.
• Systolic dysfunction often accompanies diastolic dysfunction.

Echo Assessment of Diastolic Function

• Left atrial volume index
• Mitral valve inflow
• Pulmonary vein flow
• Tissue Doppler imaging
• Pulmonary pressures

Left Atrial Volume Index

• Measurement reflects left atrial volume relative to body surface area (BSA).
• Left atrial pressure increases to fill a noncompliant left ventricle, causing left atrial enlargement.
• Ranges of severity based on values (in cc/m²) categorize normality/enlargement.

Mitral Inflow / PW Doppler

• Small sample volume (1-3 mm) is optimal
• Optimize scale and baseline
• Low filter/gain settings ideal
• Sweep speed: 100 mm/s
• Align parallel to flow

MV Inflow

• Measures key parameters: E velocity, A velocity, E/A ratio, Deceleration Time (DT), and A duration
• E wave: peak velocity during early filling.
• A wave: peak velocity during atrial contraction.
• E/A ratio: ratio of E wave velocity to A wave velocity.
• DT: time for peak velocity to reach zero during early filling.
• A duration: duration of the A wave.

Mitral Valve Inflow: E and A waves

• E wave: Peak velocity of early ventricle filling.
• A wave: Peak velocity of atrial contraction.

Mitral Valve Inflow: Deceleration Time

• Deceleration time (DT) measures the time from peak early filling velocity to zero baseline.
• Influenced by LV relaxation, filling pressures, and LV compliance.
• Normal DT: 150-200 ms.
• Grade 1 diastolic dysfunction: DT >200 ms
• Grade 3 diastolic dysfunction: DT < 150 ms

Question:

• Impact of Grade 1 diastolic dysfunction on deceleration time is longer DT than normal.
• Impact of Grade 3 diastolic dysfunction on deceleration time is shorter DT than normal.
• Impact of Grade 1 pattern on E/A ratio compared to normal diastolic function is decreased E/A ratio.
• Impact of Grade 3 pattern on E/A ratio compared to normal diastolic function is increased E/A ratio.

Mitral Valve Inflow: Diastasis

• The diastasis is a slow filling phase occurring between E and A waves.
• In normal settings, this flow is less than 0.2 m/s.
• Increased filling pressure may increase flow during diastasis

Question:

• Effect of faster HR on diastasis is decreased diastasis.

Question:

• Doppler signals needed to calculate E/e' ratio are E wave velocity and e' wave velocity.

Tissue Doppler Imaging of the MV Annulus

• Movement of the mitral valve annulus reflects properties of heart relaxation.
• Not affected by preload.
• Helpful in determining filling pressures
• Procedure involves use of apical four-chamber view, larger sample volume, precise cursor alignment to highest annulus "bounce", measurements from both medial and lateral MV annulus.

Tissue Doppler Imaging

• Adjusts Doppler signal to measure tissue mobility, not blood flow.
• Tissue velocities are lower than blood flow velocities.
• Angle dependence is an important factor when taking measurements.
• Procedure involves use of apical four-chamber view, larger sample volume, precise cursor alignment to highest annulus "bounce," measurements from both medial and lateral MV annulus.
• Measurements of s', e', and a' are taken when obtaining images of diastolic function.
• Normal e' velocity (medial): > 0.10 m/s; (lateral): > 0.13 m/s.
• Normal E/e' ratio: <8.

E/e' Ratio

• Calculated by dividing the mitral E wave by e' velocity (tissue Doppler)
• Used to estimate left atrial pressure (LAP).

Pulmonary Veins

• Left atrium fills from pulmonary veins.
• Three components to pulmonary vein flow:
  • Systolic forward flow
  • Diastolic forward flow (early diastole)
  • Atrial reversal of flow (atrial contraction)

Pulmonary Veins (PW Doppler)

• Sample volume (3-5 mm) is placed approximately 1cm into pulmonary vein.
• Optimize scale and baseline.
• Use low filters and gain settings.
• Sweep speed: 100 mm/s.
• Systolic flow velocity (S) is typically slightly higher than diastolic flow velocity (D) in normal diastolic function.
• If two systolic components exist (S1, S2), measure S2 velocity.

Pulmonary Pressures

• Left ventricular diastolic dysfunction leads to increased pulmonary pressures.
• Right ventricular systolic pressure (RVSP) = 4 (tricuspid regurgitation velocity)2 + right atrial pressure (RAP).

Right Heart/Pulmonary Pressures

• TR velocity and IVC assessment
• 4 (VTR)2 + RAP
• Significant diastolic dysfunction results in elevated pulmonary pressure (TR velocity > 2.8 m/s)
• Diastolic dysfunction is not the sole explanation for elevated pulmonary pressures.

Normal Diastolic Function, Grade 1: Summary Table

• Mitral Valve (characteristics): E < A, E/A ratio < 0.8, Decel Time > 200 ms
• Tissue Doppler MV Annulus (characteristics): e' velocity ≥0.08 m/s, E/e' ratio < 8
• Pulmonary Veins (characteristics): Systolic > diastolic, Small atrial reversal
• LA index is normal
• TR velocity < 2.8 m/sec

Normal Diastolic Function: Summary Table (practice)

• General: LA function is normal; TR velocity is less than 2.8 m/sec

Grade 1 Diastolic Dysfunction, Summary Table

• Mitral Valve: E < A, E/A ratio < 0.8, Deccel time > 200 ms
• Tissue Doppler MV Annulus: e' velocity ≥0.08 m/s, E/e' ratio <8 (possibly in indeterminate range 8-14).
• Pulmonary Veins: Systolic > diastolic, small atrial reversal.
• LA index is normal/mildly enlarged
• TR velocity < 2.8 m/sec

Grade 2 Diastolic Dysfunction, Summary Table

• Mitral Valve: E > A, E/A ratio < 1.0-1.5, Decel time 150-200 ms
• Tissue Doppler MV Annulus: e' velocity < 0.07 m/sec, E/e' ratio ≥ 14
• Pulmonary Veins: Systolic < diastolic; Larger atrial reversal.
• LA index enlarged
• TR velocity > 2.8 m/sec

Grade 3 and 4 Diastolic Dysfunction, Summary Table

• Mitral Valve: E > A, E/A ratio > 2, Decel time < 150 ms
• Tissue Doppler MV Annulus: e' and velocity < 0.07 m/sec; E/e' ratio ≥ 14 (often significantly high)
• Pulmonary Veins: Systolic < Diastolic, Blunted systolic or diastolic; Large atrial reversal.
• LA index: severely enlarged
• TR velocity > 2.8 m/sec