Comparing Doppler modalities

Modality
Clinical uses
Disadvantages
Pulsed wave
Targeted areas: Measures blood flow velocities through pulmonary veins, mitral valve, and in low flow areas in the heart
Cannot measure fast blood flow velocities; limited by Nyquist limit
Contin- uous wave
High velocities: Measures blood flow velocities through the aorta, aortic valve, stenotic valve lesions, regurgitant valvular jets
Cannot identify the location of the peak velocity along the ultrasound scan line
Color flow
Enhances the recognition of Valvular abnormalities and intracardiac shunts
Cannot measure fast blood flow velocities; limited by Nyquist limit
M-mode
Examines a line of motion over time (monodimensional view of the heart); used to view rapidly moving structures, such as valve leaflets
Orientation and interpretation of spatial relationships is difficult; can’t measure blood flow velocity