What does green colorflow signify in an echocardiogram (echo)?

Green Color Flow in Echocardiography

Green color on echocardiographic color flow Doppler signifies turbulent flow with high velocity variance, indicating disturbed blood flow patterns typically seen in stenotic lesions, regurgitant jets, or abnormal intracardiac shunts. 1, 2

Color Doppler Fundamentals

The color coding system in Doppler echocardiography follows a standardized convention 2:

• Red indicates flow moving toward the transducer
• Blue indicates flow moving away from the transducer
• Green is added to either red or blue colors in proportion to the extent of turbulence and velocity variance 2
• The brightness of red or blue represents the magnitude of flow velocity, with an 8-step brightness scale 2

Clinical Significance of Green Color Flow

Green coloring specifically represents the velocity spectrum variance component of the Doppler signal, which directly correlates with turbulent flow characteristics. 2 This turbulence occurs when:

• Blood flow becomes disorganized and chaotic rather than laminar
• Multiple velocities exist simultaneously at the same location
• High-velocity jets create shear forces and flow disturbances 1

Common Clinical Scenarios

Green color flow is characteristically seen in 1, 2:

• Valvular regurgitation jets - The turbulent regurgitant flow through incompetent valves produces prominent green coloring, particularly at the vena contracta and in the receiving chamber 1
• Valvular stenosis - High-velocity turbulent flow through narrowed valve orifices demonstrates green admixture 1
• Intracardiac shunts - Abnormal communications like ventricular septal defects or atrial septal defects show turbulent flow with green coloring 2
• Prosthetic valve dysfunction - Paravalvular leaks or valve thrombosis create turbulent jets with green variance 1

Technical Considerations

Proper Nyquist limit settings are essential for accurate interpretation, typically set at 50-60 cm/s for regurgitant jet assessment. 1 The appearance of green color is influenced by:

• Baseline Nyquist limit adjustments (standard 28 cm/s for PISA calculations) 1
• Transducer frequency and gain settings 1
• Angle of interrogation relative to flow direction 1

Diagnostic Applications

When evaluating green turbulent flow, assess 1:

• Jet origin and direction - Determines whether flow is intravalvular (through the valve) or paravalvular (around the valve/prosthesis)
• Spatial extent - Larger areas of green turbulence suggest more severe pathology
• Associated findings - Chamber dilation, wall motion abnormalities, or elevated pressures
• Multiple acoustic windows - Off-axis views may be necessary to fully characterize turbulent jets 1

Common Pitfalls

Avoid these interpretation errors 1:

• Mistaking artifact for pathologic flow - Ensure the green signal represents actual blood flow by confirming it in multiple views
• Overlooking paravalvular regurgitation - Acoustic shadowing from prosthetic valves may obscure jets; TEE is often necessary 1
• Inadequate gain settings - Excessive gain creates spurious green signals; insufficient gain may miss subtle turbulence
• Single-view assessment - Always confirm turbulent flow patterns in orthogonal imaging planes 1