<unk>  is a procedure that uses Doppler ultrasonography to examine the heart. An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows<unk> termination of the speed and direction of blood flow by utilizing the Doppler effect. An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. One of the limitations is that the ultrasound beam should be as parallel to the blood flow as possible. Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), calculation of the cardiac output and calculation of E/A ratio (a measure of diastolic dysfunction). Contrast-enhanced ultrasound-using gas-filled microbubble contrast media can be used to improve velocity or other flow-related medical measurements. An advantage of<unk>  is that it can be used to measure blood flow within the heart without invasive procedures such as cardiac catheterization. In addition, with slightly different filter/gain settings, the method can measure tissue velocities by tissue<unk> . The combination of flow and tissue velocities can be used for estimating left ventricular filling pressure, although only under certain conditions. Although "Doppler" has become synonymous with "velocity measurement" in medical imaging, in many cases it is not the frequency shift (Doppler shift) of the received signal that is measured, but the phase shift (when the received signal arrives). However, the calculation result will end up identical. This procedure is frequently used to examine children's hearts for heart disease because there is no age or size requirement.
Doppler echocardiography
Doppler ultrasonography
Intracoronary optical coherence tomography
Magnetocardiography
Phonocardiogram
Coronary CT calcium scan
Impedance cardiography
Ballistocardiography