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| L Wave on Echo |
L-Wave on Echocardiography: The Hidden Doppler Clue to Advanced Diastolic Dysfunction
What is the L-Wave?
The L-wave is a mid-diastolic transmitral flow wave seen on pulsed-wave Doppler echocardiography, occurring between the E-wave (early diastolic filling) and A-wave (atrial contraction).
It represents continued left ventricular (LV) filling during diastasis and is not a normal finding in adults. Its presence strongly suggests diastolic dysfunction with elevated left ventricular filling pressures.
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Normal Mitral Inflow Pattern (Recap)
Normal transmitral Doppler flow consists of:
E-wave → Early rapid LV filling due to pressure gradient between LA and LV
Diastasis → Minimal or no flow
A-wave → Atrial contraction
There is no mid-diastolic flow in normal physiology.
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What Causes the L-Wave?
The L-wave appears when:
LV relaxation is impaired but
LA pressure remains persistently elevated
This creates a renewed pressure gradient during mid-diastole, allowing additional flow into the LV.
Major Causes
1. Elevated LV filling pressures
Advanced diastolic dysfunction
Restrictive physiology
Heart failure with preserved EF (HFpEF)
2. Bradycardia
Prolonged diastasis allows time for mid-diastolic flow to occur
3. Atrial Fibrillation
A-wave absent
L-wave may be difficult to distinguish but can still occur due to high LA pressure
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Pathophysiology Explained Simply
Impaired LV relaxation → reduced early filling
Elevated LA pressure → persistent pressure gradient
During diastasis, blood continues to flow into LV → L-wave
This indicates advanced diastolic disease, not just mild relaxation abnormality.
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Echocardiographic Features of the L-Wave
Seen on pulsed-wave Doppler at mitral leaflet tips
Appears after E-wave and before A-wave
Best visualized at slow heart rates
Often associated with:
Enlarged left atrium
Reduced e′ velocity on tissue Doppler
Elevated E/e′ ratio
Pulmonary venous diastolic dominance
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Clinical Significance of the L-Wave
The L-wave is a marker of elevated filling pressures and has important prognostic implications.
Associated Conditions
Advanced diastolic dysfunction (Grade II–III)
HFpEF
Restrictive cardiomyopathy
Acute decompensated heart failure
Prognostic Value
Associated with worse functional class
Predicts heart failure hospitalization
Indicates poor LV compliance
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L-Wave vs Other Diastolic Patterns
Feature L-Wave Normal Restrictive Filling
Mid-diastolic flow Present Absent Often present
Filling pressure High Normal Very high
Prognosis Unfavorable Normal Poor
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Practical Tips for Detection
Reduce sweep speed to clearly visualize diastasis
Look carefully in bradycardic patients
Correlate with:
Tissue Doppler e′
LA size
TR velocity
In AF, interpret with caution due to beat-to-beat variability
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Key Take-Home Messages
L-wave = mid-diastolic LV filling
Strong indicator of elevated filling pressures
Seen in advanced diastolic dysfunction
Common in HFpEF and restrictive physiology
Has important diagnostic and prognostic value
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