Systolic Flow Reversal in Severe Tricuspid Regurgitation: An Important Doppler Sign

 Systolic Flow Reversal in Severe Tricuspid Regurgitation: An Important Doppler Sign

Tricuspid regurgitation (TR) is increasingly recognized as an important determinant of symptoms, right-sided heart failure, hospitalization, and prognosis. Echocardiography remains the primary imaging modality for evaluating TR.

Among the supportive Doppler findings of severe TR, systolic flow reversal in the hepatic veins is particularly useful. Current echocardiographic recommendations include hepatic vein systolic flow reversal among the important signs supporting severe TR.

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What Is Normal Hepatic Vein Flow?

Hepatic venous flow can be assessed using pulsed-wave (PW) Doppler, usually from the subcostal window.

A normal hepatic venous Doppler tracing contains:

S wave: Forward flow toward the right atrium during ventricular systole.

D wave: Forward flow during early ventricular diastole.

A reversal wave: Brief retrograde flow during right atrial contraction.

Normally, forward systolic flow is prominent. With increasing TR severity, the systolic component progressively decreases and may eventually reverse.

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Why Does Systolic Flow Reverse in Severe TR?

During normal ventricular systole, the tricuspid valve closes and blood is ejected from the right ventricle into the pulmonary artery.

In severe TR, a large volume of blood instead regurgitates:

RV → RA → IVC → hepatic veins

This produces a prominent systolic pressure wave within the right atrium and systemic venous circulation.

When the regurgitant pressure and volume are sufficiently large, forward hepatic venous systolic flow is overcome, producing:

Hepatic vein systolic flow reversal

In simple terms:

Normal: Hepatic vein → RA during systole

Severe TR: RA → hepatic vein during systole

This is the physiological basis of the reversed S wave.

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Progression With Increasing TR Severity

A useful conceptual progression is:

Mild TR → systolic-dominant hepatic venous flow

↓

Increasing TR → reduced/blunted S wave

↓

Severe TR → systolic flow reversal

ESC/EACVI recommendations describe hepatic vein systolic flow reversal as an important semiquantitative criterion for severe TR.

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How to Assess Hepatic Vein Flow on Echocardiography

Use the subcostal window and identify a hepatic vein draining into the inferior vena cava.

Apply color Doppler to confirm the vessel and direction of flow.

Place a PW Doppler sample volume within the hepatic vein, preferably sufficiently away from the IVC junction to obtain a clean tracing.

Record several cardiac cycles while considering respiratory variation.

Look specifically at the flow occurring during ventricular systole.

Severe TR pattern

Instead of an antegrade S wave toward the right atrium, there is a retrograde systolic wave away from the right atrium and back into the hepatic venous circulation.

Because hepatic venous flow varies significantly with respiration, assessment over multiple beats is particularly useful.

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How Strong Is This Sign?

Hepatic vein systolic flow reversal is a strong supportive sign of severe TR.

The EACVI/ESC position paper reports a sensitivity of approximately 80%, meaning that its absence does not exclude severe TR.

Therefore:

Presence of convincing systolic reversal → strongly supports severe TR

but

Absence of reversal → does not rule out severe TR

This distinction is important in everyday echo reporting.

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Systolic Blunting Is Not the Same as Systolic Reversal

These findings should not be confused.

Systolic blunting

The hepatic vein S wave becomes smaller than expected.

It may occur with increasing TR but is relatively nonspecific because it can also occur with elevated right atrial pressure, altered RA/RV compliance, and impaired RV relaxation.

Systolic reversal

Blood actually travels backward into the hepatic vein during ventricular systole.

This is much more supportive of hemodynamically important/severe TR.

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Important Pitfalls

Hepatic vein flow should never be interpreted in isolation.

The waveform can be influenced by:

Atrial fibrillation: Loss of coordinated atrial contraction and variable cycle lengths alter hepatic venous waveforms.

Right atrial pressure and compliance: A small or poorly compliant RA may generate substantial venous pressure changes even with a smaller regurgitant volume.

RV function: Reduced RV contraction and reduced tricuspid annular descent can modify the S wave.

Respiration and preload: Both significantly influence systemic venous Doppler velocities.

Rhythm abnormalities: Junctional or ventricular rhythms with retrograde atrial activation can occasionally produce systolic hepatic venous reversal unrelated to severe TR.

Therefore, hepatic vein reversal should be incorporated into an integrative assessment of TR severity.

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Other Echocardiographic Findings Supporting Severe TR

Hepatic vein systolic reversal becomes particularly convincing when accompanied by other features of severe TR.

Important findings include:

Vena contracta width ≥7 mm

EROA ≥40 mm²

Regurgitant volume ≥45 mL/beat

Large central or eccentric regurgitant jet

PISA radius >9 mm under guideline-specified settings

Dense, triangular, early-peaking CW Doppler envelope

RA and RV enlargement

Dilated IVC

The ESC/EACTS guideline includes hepatic vein systolic flow reversal alongside these parameters in the integrated grading of severe TR.

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Why Can TR Velocity Be Low Despite Severe TR?

This is an important clinical pearl.

A very high TR velocity does not necessarily mean more severe regurgitation.

In very severe TR, right ventricular and right atrial pressures may equalize rapidly during systole. Consequently, the pressure gradient across the tricuspid valve falls and the TR jet may have a relatively low peak velocity.

The CW Doppler signal may instead become:

Dense

Triangular

Early peaking

This is another reason TR severity should never be determined from peak TR velocity alone.

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Clinical Significance

Severe TR causes transmission of systolic pressure and volume into the systemic venous circulation.

This may contribute to:

Jugular venous V waves

Hepatic pulsatility

IVC dilatation

Hepatic congestion

Peripheral edema

Ascites

Progressive right-sided heart failure

Thus, hepatic vein systolic reversal is more than an echocardiographic curiosity—it reflects the hemodynamic transmission of severe regurgitation into the systemic venous circulation.

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Practical Echo Reporting

When a convincing waveform is obtained, a useful report statement is:

“Pulsed-wave Doppler demonstrates systolic flow reversal in the hepatic veins, supporting significant/severe tricuspid regurgitation in the appropriate clinical and echocardiographic context.”

It is preferable not to diagnose severe TR solely from hepatic venous flow. TR severity should be based on integration of valve morphology, color Doppler, vena contracta, CW Doppler, quantitative parameters, hepatic venous flow, and right-heart remodeling.

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Key Takeaway

Hepatic vein systolic flow reversal is an important supportive Doppler sign of severe tricuspid regurgitation.

The mechanism is straightforward:

Severe TR → large systolic regurgitant flow into RA → systolic pressure/volume transmission into IVC and hepatic veins → reversal of hepatic venous S wave.

Its presence strongly supports severe TR, but its absence does not exclude severe disease, and rhythm, loading conditions, right atrial compliance, and RV function must always be considered.

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