L’ wave in echocardiogram

‘L’ Wave in Echocardiography – Explained

The ‘L’ wave is a mid-diastolic transmitral flow signal seen on pulsed-wave Doppler imaging of the mitral inflow in certain pathological conditions.

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What is the ‘L’ wave?

• It is an additional diastolic wave between the E wave (early filling) and A wave (atrial contraction) on mitral inflow Doppler.
• Appears after the E wave but before the A wave during mid-diastole.
• It reflects mid-diastolic mitral inflow due to persistent or increased left atrial pressure gradient across the mitral valve during diastole.

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Echocardiographic Appearance

• Detected in apical 4-chamber view with pulsed-wave Doppler at the mitral leaflet tips.
• The Doppler flow pattern shows:
  E wave → L wave → A wave

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Conditions Associated with L Wave

Condition	Explanation
Diastolic Dysfunction (Grade 2 or 3)	Impaired relaxation with elevated LV filling pressures
Advanced Heart Failure	With elevated left atrial pressure and pseudonormal/restrictive filling
Atrial Fibrillation	Seen due to loss of A wave and compensatory filling
Post-cardiac transplant	Can occur due to abnormal diastolic compliance
Constrictive Pericarditis or Restrictive Cardiomyopathy	Due to rapid early filling and stiff ventricles

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Mechanism Behind the L Wave

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• In mid-diastole, there’s usually a pause in mitral flow.
• However, in certain diseases, LA pressure remains elevated, causing persistent flow across the mitral valve even in mid-diastole.
• This causes an extra wave—the L wave—to appear.

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Clinical Significance

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• Marker of elevated left ventricular filling pressure.
• May suggest adverse prognosis in heart failure.
• Useful in non-invasive grading of diastolic dysfunction.

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Mnemonic: “EL-A” pattern

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Early diastolic
Late-mid diastolic
Atrial contraction
(E → L → A)

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1. What is the L wave in mitral inflow Doppler?

1. It is a mid-diastolic flow signal seen between the E and A waves.
2. Detected on pulsed-wave Doppler at the mitral leaflet tips.
3. It appears due to persistent pressure gradient from LA to LV in mid-diastole.
4. It is often observed in pathological diastolic filling conditions.
5. The pattern seen is E-L-A (Early, Mid, and Atrial filling waves).

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2. What are the conditions associated with the presence of an L wave?

1. Grade 2 and Grade 3 diastolic dysfunction.
2. Advanced heart failure with raised LV filling pressure.
3. Atrial fibrillation (absence of A wave makes L wave more visible).
4. Restrictive cardiomyopathy and constrictive pericarditis.
5. Post-cardiac transplant due to altered compliance.

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3. What does the presence of an L wave indicate clinically?

1. It suggests elevated left ventricular filling pressures.
2. Associated with abnormal diastolic function.
3. May reflect reduced LV compliance.
4. Indicates worse prognosis in some heart failure patients.
5. Helps grade diastolic dysfunction in echocardiography.

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4. How is the L wave detected on echocardiography?

1. Use pulsed-wave Doppler at the mitral leaflet tips.
2. Typically assessed in the apical 4-chamber view.
3. Appears between the early (E) and late (A) diastolic waves.
4. Seen as a distinct mid-diastolic positive wave.
5. Requires slow heart rate or high filling pressure to be clearly visualized.

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5. What are the hemodynamic mechanisms that lead to L wave formation?

1. Persistent pressure gradient between LA and LV during mid-diastole.
2. High LA pressure sustains flow across mitral valve.
3. Rapid early filling followed by a brief mid-diastolic flow pause.
4. Then mid-diastolic LA pressure rises again, causing another wave (L wave).
5. Reflects altered ventricular relaxation or stiffness.

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6. How does atrial fibrillation affect L wave visibility?

1. A wave is absent due to lack of atrial contraction.
2. Makes L wave more prominent and easier to detect.
3. E-L pattern replaces the usual E-A pattern.
4. Seen in AF patients with elevated LA pressure.
5. Useful in evaluating diastolic function in AF.

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7. What is the timing of the L wave during the cardiac cycle?

1. Occurs during mid-diastole.
2. Appears after the E wave but before the A wave.
3. Usually around 150–200 milliseconds after E wave.
4. Detected between rapid early filling and atrial contraction.
5. Only visible when diastolic filling duration is sufficient.

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8. What is the prognostic significance of the L wave?

1. Associated with elevated left-sided filling pressures.
2. Suggests more advanced diastolic dysfunction.
3. May predict worse outcomes in heart failure patients.
4. Indicates impaired ventricular relaxation and compliance.
5. Disappearance may reflect successful therapy.

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9. How does heart rate affect the appearance of the L wave?

1. Bradycardia enhances its visibility.
2. Prolonged diastole separates E, L, and A waves clearly.
3. Tachycardia may fuse E and L waves, making L wave undetectable.
4. Very fast rates can eliminate mid-diastolic flow.
5. Best detected in slow to moderate heart rates.

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10. What is the significance of the E-L-A pattern on mitral Doppler?

1. Helps in grading and identifying advanced diastolic dysfunction.
2. It indicates presence of L wave between E and A waves.
3. Suggests abnormal diastolic filling dynamics.
4. Seen in restrictive or pseudonormal filling patterns.
5. Reflects elevated LA pressure during all phases of diastole.

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Types of L- Wave in Echocardiogram

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Two types of L-waves.

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Type I

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Distinct L-wave (Type I) with an accelerating and decelerating portion.

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Type II

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Merged L-wave (Type II) having only a decelerating portion, manifesting as an abrupt change in the deceleration segment of the flow profile

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