|Year : 2017 | Volume
| Issue : 3 | Page : 214-221
Echocardiographic assessment of diastolic function
Department of Non-invasive Cardiology, Apollo Gleneagles Hospital, Kolkata, West Bengal, India
|Date of Web Publication||12-Dec-2017|
Dr. Aniruddha De
Department of Non-invasive Cardiology, Apollo Gleneagles Hospital, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
The stepwise approach in evaluation of left ventricular (LV) diastolic function is essential in any patients with dyspnea on exertion or heart failure. Many of them have normal to near-normal ejection fractions (EFs). These subsets of patients are labeled as diastolic heart failure or heart failure with preserved EF. It is important to differentiate diastolic dysfunction from dyspnea of pulmonary origin for further management and future prognosis. LV filling pressures is usually synonymous with pulmonary capillary wedge pressure (PCWP), mean left atrial pressure (LAP), mean LV diastolic pressure, and LV end-diastolic pressure (LVEDP). PCWP on the other hand is also an indirect estimate of LV diastolic pressures. LVEDP is often elevated in early diastolic dysfunction because of a large atrial pressure wave, while mean PCWP and LAP remain normal. While mean PCWP and LAP increased during tachycardia and where there is increased LV afterload which is the basis for the diastolic stress test. It is essential that certain Doppler variables correlate well with an increase in LVEDP only and not reflecting the increase in either LAP or LVEDP. Therefore, early evaluation of LV filling pressures and LVEDP are more important than mean LA pressure which is elevated later. Echocardiography is the best evaluation tool to evaluate LV diastolic function. The purpose of this article is to provide the simplest stepwise approach of different diastolic parameters which are used as routine protocol with minimal use of the newer modalities at various clinical settings.
Keywords: Diastolic function, echocardiography, LV filling pressure
|How to cite this article:|
De A. Echocardiographic assessment of diastolic function. J Indian Acad Echocardiogr Cardiovasc Imaging 2017;1:214-21
| Echocardiographic Assessment of Diastolic Function|| |
- It is recommended to record:
- Clinical profile (height, weight, body surface area, relevant history, and physical examination)
- Heart rate
- Blood pressure
- Echo findings: Left ventricular (LV) wall thickness, regional wall motion abnormality, LV volume, ejection fraction (EF)
- Left atrial (LA) volume
- Any rhythm abnormality
- Morphology of mitral valve (MV) for proper evaluation diastolic function in various and specific clinical conditions.
- Each parameter has its own limitation and signals should be assessed carefully. Suboptimal Doppler signals are not included in final evaluation of LV diastolic function.
- Single normal measurement does not indicate normal diastolic function because several hemodynamic factors affect any particular signal and few measurements may be normal in the presence of diastolic dysfunction. Hence, no single parameter should be used alone. Always two or more of the indices should be taken for a given individual. The echo parameters of diastolic dysfunction may not be always correct in normal subject with normal echocardiographic findings.
- The following parameters are routinely used for the evaluation of diastolic function:
- Transmitral Doppler inflow
- Tissue Doppler imaging (TDI)
- Pulmonary venous Doppler flow.
| How to Record These Parameters|| |
Transmitral Doppler inflow [Figure 1] and [Figure 2]
- Normal pattern of LV diastolic filling is recorded with pulsed Doppler. Apical four-chamber (4Ch) view with color flow imaging is used for spectral Doppler. Mitral inflow velocities are recorded by PW Doppler after proper alignment,
- Sample volume (1–3 mm) is placed at the tip of mitral leaflet and record peak modal velocity in early diastole for peak E wave which corresponds to T wave in electrocardiogram (ECG) and in late diastole for A wave which correspond to P wave in ECG. There should not be any spikes or feathering in optimal waveform. It is recommended that signal gain and filter setting should be kept at minimum level (100–200 MHz)
- Primary measurements are peak E and A velocities, E/A ratio, isovolumic relaxation time (IVRT) and deceleration time (DT),
- MV A duration (ms) is also measured: Here, sample volume (1–3 mm) is placed at the level of mitral annulus between annulus and leaflet tips). There should not be any spikes or feathering in optimal waveform
- Mitral inflow patterns are four types: normal, impaired relaxation, pseudonormal, and restrictive pattern
- Filling patterns are better indicator of functional class and prognosis of disease than LVEF in dilated cardiomyopathies.
Tissue Doppler imaging [Figure 3] and [Figure 4]
- Mitral annular velocities are measured by tissue by PW from the apical 4Ch view,,
- Sample volume of 5–10 mm by PW Doppler is measured at mitral septal and lateral annulus. Then, average e' velocity is calculated. Position of sample volume should be kept in the septal and lateral wall within 1 cm from the junction of the mitral leaflet with the walls
- There should not be any spikes or feathering in optimal waveform. It is recommended that signal gain and filter setting should be kept at minimum level
- Measure the average of 3 consecutive cardiac cycles. The measurement should be done at end-expiration. The sweep speed should be kept at 50–100 mm/s
- Systolic, early (e') and late (a') diastolic velocities should be measured
- E/e' ratio is an excellent parameter of LV filling pressures in a patient with cardiac disease
- However, the E/e' ratio is not a consistent indicator of LV filling pressures, for example, normal individual, constrictive pericarditis, severe mitral annular calcification (MAC), and MV disease.
Patients with EF <50%, DT, and mean LV end-diastolic pressure (LVEDP) correlate well but not if EF >50%. E/A better correlated with LVEDP if EF is <50%. LV chamber is distorted by infarction, LVH, cardiomyopathy, and dyssynchrony which will impair blood flow from mitral orifice to LV apex. TDI is limited by non-uniform LV relaxation in patients with CAD and MAC. Multiple factors influence mitral inflow velocities: left atrial pressure (LAP) and compliance, pliability of MV, ventricular compliance, ventricular relaxation, and suction. E/e' ratio is best available indicator for the evaluation of mean LVEDP. If it is <8, then it regarded as normal and if >15, then it regarded as abnormal but cannot be used in isolation. E/e' is not always correct in determining LV filling pressures in decompensated and severe systolic dysfunction. E velocity depends on stroke volume, but no linear correlation is found with elevated LV filling pressure. E/e' estimation may not be accurate in patients with severe mitral regurgitation, intraventricular conduction disturbances, and with pacemaker implantation.,,
Pulmonary venous Doppler flow [Figure 5], [Figure 6], [Figure 7], [Figure 8]
- Pulmonary venous flow is evaluated by PW Doppler from apical 4Ch view,
- For optimal spectral waveforms, sample volume (1–3 mm) is placed 1–2 cm inside the pulmonary vein
- There should not be any spikes or feathering in optimal waveform. It is recommended that signal gain and filter setting should be kept at minimum level (100–200 MHz)
- Peak modal velocity at leading edge of spectral Doppler is measured. Peak S wave is measured at early systole, D wave at early diastole, and peak Ar velocity in late diastole. Then, the S/D ratio and systolic filling fraction are recorded. Another important parameter is (Ar A) measurement which is calculated by the time difference between Ar duration and mitral A-wave duration
- Ar velocity, duration, and Ar A duration increased when LVEDP is elevated.
S = Inward systolic flow: LA relaxation and LV contraction: with mitral annular descent to the apex. D = Forward flow during diastole similar to an E velocity (normal D>>S but older than 60 year S >D). A - Atrial systole, retrograde flow from LA to pulmonary vein (if Ar is increased then LVEDP is increased).
Normal parameters: Forward flow (systolic and diastolic) and flow reversal during atrial contraction (Ar).
Reduced flow into the LV during atrial contraction is noted due to increased resistance. Increased resistance is often observed when compliance of LV decreases with subsequent elevation of LV filling pressure. As a result, forward flow into LV is reduced and more back flow of blood into the PV is noted during atrial contraction. Hence, compliance is calculated indirectly by the ratio between forward and back flow. Patient with elevated LAP and low EF, systolic flow is decreased. Higher S/D velocity ratio is observed when there is impaired relaxation of ventricle and low S/D ratio is found with restriction abnormality while evaluating the pulmonary velocity curves.
| Diastolic Dysfunction Evaluated Based on the above Parameters|| |
The four recommended parameters and their values:
- Annular e' velocity (septal e' <7 cm/s, lateral e' <10 cm/s),
- Average E/e' ratio >14,
- LA maximum volume index >34 mL/m2, and
- Peak tricuspid regurgitation (TR) velocity >2.8 m/s.
If a single clinically relevant parameter is available, for example, lateral e' or septal e' velocity, then E/e' ratio >13 at lateral annulus or E/e' >15 at septal annulus is considered abnormal.
If >50% of the available variables are not abnormal, then LV diastolic function should be considered normal.
If >50% of the available variables are abnormal, then there is LV diastolic dysfunction.
If 50% of the available parameters are not matching the values, then study is considered inconclusive.
| If the Study Is Inconclusive, Then Other Diastolic Indices Are Evaluated|| |
- Valsalva maneuver
- Isovolumic relaxation time (IVRT)
- Mitral inflow propagation velocity (Vp)
- Tissue Doppler (TD) echocardiographic time intervals (TE-e').
Valsalva maneuver [Figure 9] and [Figure 10]
This maneuver is done by continuous recording and patient was asked to perform forced expiration for 10 s. During the procedure, mouth and nose should be closed. Measure the change in MV inflow parameters: E velocity and E/A ratio. Furthermore, measure the same during peak strain and subsequent release. The difference of time between Ar velocity of pulmonary vein and mitral A velocity is also recorded. This maneuver can differentiate normal from pseudonormal pattern and reversible restrictive LV filling from irreversible one. More than 50% reduction in E/A ratio and increase Ar velocity duration than mitral A duration (Ar-A) is highly specific for evaluation of increased LV filling pressures, LVEDP, and diastolic dysfunction.
Isovolumic relaxation time [Figure 11] and [Figure 12]
|Figure 11: Position of PW Doppler in left ventricular outflow tract for isovolumic relaxation time|
Click here to view
Always recorded at apical long-axis or five-chamber view (5Ch). CW Doppler is placed in the LV outflow tract (LVOT). Spectral Doppler of aortic ejection and mitral inflow are recorded at the same time. IVRT is the time duration between closure of aortic valve and opening of MV. Sweep speed should be kept at 100 mm/s.
Transducer at apex with pulse or continuous Doppler between LVOT and MV in apical long or 5Ch. Normal duration of IVRT: 70–90 ms. In patients with impaired LV relaxation, length of IVRT increases, and when LV compliance is decreased, IVRT shortens, and short IVRT is also seen when LV filling pressures is increased. IVRT always depends on heart rate, preload, and ventricular function. IVRT may be useful to follow clinical response to treatment with congestive heart failure or post MI with restrictive filling. Pseudonormal and restriction can have short IVRT, otherwise all are above 90 ms. Early on, there is a delay in emptying and DT >240 ms. As a result, there will be partial compensation by more powerful end-diastolic atrial contraction. Hence, measured E/A is reduced <0.9. Atrial pressure increases and DT shortens whenever there is increased impedance to atrial emptying and atrioventricular pressure difference is reduced. Now E and E/A will increase, so there is pseudonormalization pattern (however the e' remains reduced). Grade III diastolic dysfunction is reversible with valsalva's maneuver whereas Grade IV is irreversibly restrictive and indicate poor prognosis. The valsalva maneuver is done by forced expiration for 10 s. During the procedure, mouth and nose should be closed and the pressure was kept around 40 mm Hg. The hemodynamic process is divided into 4 phases. Reduction >50% in the E/A ratio is highly specific for increased LV filling pressures. However, small percentage of changes does not indicate normal diastolic function.
Mitral inflow propagation velocity and hepatic vein Doppler [Figure 13] and [Figure 14]
M-mode of color flow is imaged from apical 4Ch view. Reduced the color scale to lower velocity and adjust the Nyquist limit to obtain a clear wave front of propagation. Tracing the slope of first aliasing velocity from the opening of MV for 4 cm into the LV cavity is done.
M-mode propagation velocity is recorded from apical 4Ch view. M-mode cursor is kept at the center of the mitral annulus during color Doppler imaging. The slope of the Doppler flow as it moves from the annulus to the apex that reflects the rate of LV relaxation. Adjustment of Nyquist limit done to keep the central jet blue and Vp is measured from the slope of aliasing during early rapid filling phase. Normal Vp >50 cm/sec and wave of relaxation moves from apex toward base. Blood is sucked into the LV cavity due to pressure gradient from base to apex. Vp (like e') correlates to LV relaxation (inversely) and LV filling pressure can be estimated by E/Vp ratio. Normal ratio is 1.5 and 2.5 suggests pulmonary capillary wedge pressure (PCWP) >15 mmHg. Often E/Vp ratio is not accurate in LVH and where LV cavity size is small. A note of caution will also remain with normal EF and normal LV volume.
Tissue Doppler echocardiographic time intervals (TE-e') [Figure 15]a and [Figure 15]b
|Figure 15: (a and b) Tissue Doppler echocardiographic time interval (TE-e')|
Click here to view
It is performed from apical 4Ch view. Spectral TD velocities of mitral inflow with perfect alignment are measured at both septal and lateral mitral annulus. Two time intervals are measured: one between tip of R wave in ECG and start of mitral E velocity and another between tip of R wave in ECG and beginning of e' velocity. The difference of those two time intervals is called TD echocardiographic time intervals. Heart rate should be matched in both occasions. Gain and filter settings are adjusted to minimize noise and sweep speed during recording is kept at 100 mm/s.
Time intervals from four annular sites are measured and average is taken and is more accurate than a single site measurement. Time intervals' measurement is important where E/e' ratio fall between 8 and 15, patients with MV lesion and normal EF. Another parameter is IVRT/TE-e' ratio. Patients with increased LV filling pressures IVRT/TE-e' ratio are usually <2. Hence, both IVRT and time interval (TE-e') should be measured together. IVRT/TE-e' ratio is inversely proportional to mean LAP. It is mandatory to measure the time intervals from at least 3 cardiac cycles and take the average. Hence, single cycle E/e' ratio concept using a dual Doppler echocardiographic probe is now a practical approach.
| Estimation of Left Ventricular Filling Pressures in Specific Clinical Situations|| |
These usual parameters are useful in the presence or absence of dynamic (mid-cavity or LVOT) obstruction and less than moderate mitral regurgitation. However, recommended parameters in moderate-to-severe MR: Ar-A duration ≥30 ms and peak TR jet velocity 2.8 m/s.
Patients with mitral stenosis, mitral regurgitation, and mitral annular calcification
Parameters in mitral stenosis are:
- IVRT: <60 ms, IVRT/TE-e': <4.2 and mitral A velocity: >1.5 m/s
- IVRT/TE-e' ratio: Good index of mean PCWP and mean LAP
- E/e' ratio is not useful.
In mitral regurgitation:
- Ar A: >30 ms, IVRT: <60 ms
- IVRT/TE-e': <3 (MR with preserved LVEF),
- Average E/e': >15 (MR with depressed EF).
Aortic stenosis and regurgitation
Standard guidelines are followed in patients with aortic stenosis.
- Average E/e' ratio >14
- Peak velocity of TR >2.8 m/s.
Diastolic dysfunction in mitral prosthesis
- Pulmonary venous Doppler, peak velocity of TR, and ratio of IVRT to TE-e' are useful
- Paravalvular regurgitation and dysfunction of prosthetic valve should be excluded because LAP is elevated in these conditions.
Diastolic dysfunction in heart transplantation
- Restrictive type of diastolic filling are observed usually after heart transplantation
- May get normal diastolic function if donor hearts are healthy
- To predict graft rejection, peak velocity of TR is only helpful parameter in evaluating mean LAP provided pulmonary causes are excluded.
Diastolic function in atrial fibrillation
Atrial fibrillation is a difficult condition for evaluation of diastolic function and elevated LAP:
- A short DT (130 ms) indicate poor prognosis due to elevated LV filling pressure
- E/e' is usually used to estimate LV filling pressure
- Peak acceleration rate of mitral E velocity (>1,900 cm/s2),
- IVRT (<65 ms),
- DT of pulmonary venous diastolic velocity (<220 ms),
- E/Vp ratio (>1.4) and
- Septal E/e' ratio (>11),
- Peak TR velocity > 2.8 m/s
- Variation of RR cycle length is overcome by multiple measurements where there is less beat to beat variation.
Diastolic function in atrioventricular block and pacing
- If mitral E and A velocities are not fused then no problem in evaluating diastolic parameters with first degree AV block
- E/e' ratio is not useful in patient with left bundle branch block and after implantation of pacemaker or cardiac resynchronization therapy
- Most useful indicator for LV filling pressure is peak velocity of TR >2.8 m/s.
Diastolic stress test
- Patients presented with dyspnea on exertion, it is essential to evaluate LV filling pressure during exercise if found normal at rest
- Mitral inflow E, annular e' velocities and peak velocity of TR are measured at rest and during exercise
- Often it is necessary to measure the parameters 1–2 min after stoppage of exercise where E and A of mitral inflow velocities fail to merge
- It is important to note that filling pressures remain elevated even few minutes after cessation of exercise
- Standard treadmill protocols are followed during diastolic stress test
- Mitral inflow velocities are recorded by placing pulsed Doppler at the mitral tips
- Mitral annular velocities are measured by spectral Doppler
- Peak velocity of TR is measured by CW Doppler
- Positive diastolic stress test indicates increased LAP. As a result, velocity of mitral E wave is increased and annular e' wave is preserved and subsequent increase in the pulmonary artery pressure
- Negative diastolic stress test: proportionate increase of e' and mitral E velocities with constant E/e' ratio during exercise,
- Hence, major indications of diastolic stress test are dyspnea and early-diastolic dysfunction at rest.
Grades of diastolic dysfuncion
- Normal appearance
- Grade 1: Impaired relaxation: Ventricle fails to relax fully, LA contribution augmented
- Grade 2: Pseudonormal appearance: Ventricle fails to relax, LAP rises
- Grade 3 and 4: Restrictive pattern: The ventricle is very stiff and noncompliant, atrial contraction fails to pump more blood.
Clinical utility of diastolic dysfunction
- It is always a big question why is the difference in clinical symptoms between patients with similar EF
- The dynamic of cardiac dysfunction in heart failure with preserved EF is always a challenge, and the best guide at present is to evaluate the elevated LV filling pressures regardless of EF
- It is our objective to maximize diastolic reserve during heart failure therapy
- In majority of heart failure patients, e' remains depressed, so any correction of myocardial performance cause increase in e' by improving myocardial relaxation
- Impaired relaxation pattern (E/A <1) indicates relatively normal LAP and the goal of optimal filling pattern is to achieve impaired relaxation pattern
- During treatment when impaired relaxation pattern is achieved, there is very little scope for further improvement by increasing the dose of diuretics and it is equally important to maintain sinus rhythm for atrial contribution to LV filling
- If there is echocardiographic evidence of increased filling pressure, diastolic reserve and symptoms may improve by preload reduction and diuresis
- In patient with advanced diastolic dysfunction, if there is no improvement in spite of proper and adequate medical therapy, then outcome is very bad. It is very important to note that there is no bradycardia during treatment as stroke volume is already compromised in this situation
- Recurrent heart failure symptoms and hospitalization are frequent if there is persistent increased filling pressure with minimal diastolic reserve in spite of aggressive treatment. Normal filling pressure indicates that the patient's treatment is optimized
- Programming of the A-V interval in patients with pacemakers is well guided by LV filling pattern
- Normal LV filling pattern is used as a screening tool in a community for predicting excellent prognosis. On the other hand, an abnormal filling pattern indicates increased risk of morbidity and mortality. Increased mortality is also directly proportional to increased abnormalities of LV filling pattern (restrictive filling > pseudo normal > impaired relaxation)
- Grade of diastolic dysfunction is a better indicator of exercise intolerance, then LVEF and diastolic dysfunction are an excellent predictor of mortality than LVEF even in heart failure patient.
Clinical report of diastolic function
- LV diastolic function should be reported whenever possible. This is more important in patient presenting with dyspnea or evidences of cardiac failure. It is mandatory to mention the diastolic function as normal, elevated, or indeterminate
- It is important to estimate LV filling pressures and mention in the report. Grade of diastolic dysfunction should also be recorded. Any changes from earlier studies should be compared and reported in conclusion
- Diastolic stress test is considered only in symptomatic patient with early-diastolic dysfunction
- Any discrepancy between right and LV filling pressures may indicate pulmonary vascular disease. Right heart catheterization may be done in this type of patient particularly if PCWP is elevated.
| Conclusion|| |
Diastole is a complex, energy-dependent process. Echo indices of diastolic function include transmitral Doppler inflow, TD velocities, pulmonary venous Doppler study, and Color M-mode propagation velocity. Diastolic dysfunction is a measurable, step-wise progression from normal to irreversible.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15]