7

Ventricular Diastolic Filling and Function

Basic Principles

1. ▪ Diastolic dysfunction often occurs in association with abnormal imaging findings (e.g., left ventricular (LV) hypertrophy or impaired systolic function).
   
2. ▪ Diastolic dysfunction may be the earliest sign of cardiac disease, often with Doppler findings antedating clinical or imaging signs of dysfunction.
   
3. ▪ Chronic elevation of LV diastolic pressure often leads to left atrium (LA) enlargement, a key element in evaluation of LV diastolic dysfunction.

Step-By-Step Approach

Step 1: Measure Left Ventricular Inflow Velocities

1. ▪ LV inflow velocities are recorded at the mitral leaflet tips and at the mitral annulus (Fig. 7.1).
   
2. ▪ Standard measurements are E velocity and deceleration time, and A velocity and duration (Fig. 7.2).
   
3. ▪ The normal pattern of a higher E than A velocity is reversed with impaired early diastolic relaxation, but the pattern may be “pseudo-normalized” with more severe diastolic dysfunction.

Key Points

• □ LV inflow velocities are recorded at the mitral leaflet tips (highest velocity signal) in the apical 4-chamber view using pulsed Doppler with a sample volume of 2.0 to 2.5 mm in length.
  
• □ The Doppler scale, baseline, and gain are adjusted to show a clear velocity curve.
  
• □ Low wall filter settings allow accurate measurements that require identification of where the velocity signal intersects the baseline (Fig. 7.3).
  
• □ Recordings at the leaflet tips are used to measure E and A velocity and deceleration slope. Recordings at the annulus are used to measure A duration.
  
• □ A transient decrease in preload may unmask an impaired relaxation filling pattern in patients with superimposed elevated filling pressures. This is shown by recording LV inflow at the mitral leaflet tips while the patient performs a Valsalva maneuver.

Step 2: Record Left Atrial Inflow

1. ▪ LA inflow velocities are recorded in the right superior pulmonary vein from an apical 4-chamber view on transthoracic echocardiography (TTE) or in any pulmonary vein on transesophageal echocardiography (TEE) (Fig. 7.4).
   
2. ▪ Standard measurements are peak systolic velocity, peak diastolic velocity, and the atrial velocity peak and duration (a_dur) (Fig. 7.5).
   
3. ▪ A PV_a greater than 0.35 m/s and an a_dur 20 ms longer than transmitral A duration indicate an elevated LV end-diastolic pressure.

Key Points

• □ LA inflow velocities from the transthoracic approach may be difficult to record due to poor signal strength at the depth of the pulmonary vein.
  
• □ Color flow imaging may be helpful in locating the pulmonary vein and optimizing sample volume position. The 2- to 3-mm length sample volume should be at least 1 cm into the pulmonary vein (Fig. 7.6).
  
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• □ The Doppler scale, baseline, and gain are adjusted to show a clear spectral signal.
  
• □ Low wall filter settings allow accurate measurements that require identification of where the velocity signal intersects the baseline.

Step 3: Record Tissue Doppler at the Mitral Annulus

1. ▪ Tissue Doppler myocardial velocities are recorded adjacent to the mitral annulus from a TTE apical approach (Fig. 7.7).
   
2. ▪ Standard measurements are the early myocardial velocity (E′) and atrial myocardial velocity (A′) (Fig. 7.8).
   
3. ▪ An E′/A′ ratio more than 1.0 is normal, with a reduced ratio indicating impaired early diastolic relaxation.
   
4. ▪ A ratio of the transmitral E velocity to the tissue Doppler E′ velocity greater than 15 predicts an LV end-diastolic pressure more than 15 mm Hg.

Key Points

• □ In the apical 4-chamber view, a small (2 mm) sample volume is positioned in the myocardium about 1 cm from the mitral annulus. The tissue Doppler instrument settings include a velocity scale of about 0.2 m/s, low gain settings, low velocity scale, and low wall filters.
  
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• □ Tissue Doppler recordings at the septal side of the annulus are more reproducible than signals from the lateral wall.
  
• □ The E′ and A′ velocities are less dependent on preload than the transmitral flow velocities.

Step 4: Measure the Isovolumic Relaxation Time

1. ▪ Pulsed Doppler is used to show the time interval between aortic valve closure and mitral valve opening (the isovolumic relaxation time [IVRT]) (Fig. 7.9).
   
2. ▪ The IVRT normally 50 to 100 ms, is prolonged with impaired relaxation but is shortened with severe diastolic dysfunction and reduced compliance (Fig. 7.10).

Key Points

• □ In an anteriorly angulated 4-chamber view, a 2- to 3-mm sample volume is positioned midway between aortic and mitral valves to show both LV ejection and LV filling velocity curves.
  
• □ The wall filters are set at a low level to identify the end of aortic outflow and onset of mitral inflow at their intersection with the baseline.
  
• □ The time interval is measured in milliseconds (ms).

Step 5: Consider Other Useful Measurements

1. ▪ The diastolic slope of the apical color M-mode recording of LV inflow (the propagation velocity) reflects the rate of LV diastolic relaxation (Fig. 7.11).
   
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6. ▪ The rate of decline in velocity of the mitral regurgitant jet at end-systole reflects the early diastolic rate of decline in LV pressure (Fig. 7.12).

Key Points

• □ Propagation velocity is measured from an apical view using a narrow sector, a depth that just includes the mitral annulus, with the aliasing velocity set to 0.5 to 0.7 m/s, at a fast (100 to 200 mm/s) sweep speed.
  
• □ The early diastolic −dP/dt is measured from the mitral regurgitant continuous-wave (CW) Doppler curve by measuring the time interval between 3 and 1 m/s and dividing by 32 mm Hg (analogous to measurement of +dP/dt from the early systolic part of the mitral regurgitant velocity curve).

Step 6: Integrate the Data (Table 7.1)

1. ▪ Measurement of LA size (diameter and/or indexed volume) is useful in the assessment of diastolic function. Chronically elevated LV filling pressure leads to increased LA chamber size.
   
2. ▪ Based on integration of data from LA size, LV filling velocities, LA filling velocities, tissue Doppler, and IVRT, diastolic dysfunction can be detected and graded (Fig. 7.13).
   
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7. ▪ The clinical interpretation of the data also takes several other factors into consideration, including mitral regurgitation, LV systolic function, LV wall thickness, and clinical signs and symptoms.

Normal Diastolic Function (Fig. 7.14)

Characteristic Features

1. ▪ Normal LA size.
   
2. ▪ Transmitral E/A velocity ratio between 1 and 2.
   
3. ▪ E deceleration time 150 to 200 ms.
   
4. ▪ Tissue Doppler E′/A′ ratio of 1 to 2.
   
5. ▪ Pulmonary vein systolic to diastolic flow ratio of 1 or more.
   
6. ▪ Pulmonary vein a-velocity less than 0.35 m/s and duration less than 20 ms longer than transmitral A duration.

TABLE 7.1

Classification of Diastolic Dysfunction∗

	Normal	Mild (Grade I)	Moderate (Grade II)	Severe † (Grade III)
Pathophysiology		↓ Relaxation Normal LV EDP	↓ Relaxation and ↑ LV EDP	↓ Compliance and ↑ ↑ LV EDP
E/A ratio ¶	≥0.8	<0.8	>0.8 to <2.0 §	≥2.0
Valsalva ΔE/A		<0.5	≥0.5	≥0.5
DT (ms)	150-200	>200	150-200	<150
E′ velocity (cm/s)	≥10	<8	<8	<5
E/E′ ratio	≤10	≤10	10-14	>14
IVRT (ms)	50-100	≥100	60-100	≤60
PV S/D	≅1	S > D	S < D	S << D
PVa (m/s)	<0.35	<0.35‡	≥0.35	≥0.35
a dur–A dur (ms)	<20	<20‡	≥30	≥30
LA volume index	<34 mL/m2	Mildly enlarged	Moderately enlarged	Severely enlarged

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1. Specialized Echocardiography Applications
2. Intraoperative and Interventional Echocardiography
3. Endocarditis
4. Valvular Regurgitation

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