Philips S4-2 Clinic Affiniti 50 Cardiac Ultrasound Probe

Knowledge point

Doppler ultrasonography

Doppler ultrasonography employs the Doppler effect to assess whether structures (usually blood)[32] are moving towards or away from the probe, and its relative velocity. By calculating the frequency shift of a particular sample volume, for example flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized. Color Doppler is the measurement of velocity by color scale. Color Doppler images are generally combined with gray scale (B-mode) images to display duplex ultrasonography images.Uses include:

• Doppler echocardiography, the use of Doppler ultrasonography to examine the heart. 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. 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[35] (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.
• Transcranial Doppler (TCD) and transcranial color Doppler (TCCD), which measure the velocity of blood flow through the brain's blood vessels transcranially (through the cranium). They are used as tests to help diagnose emboli, stenosis, vasospasm from a subarachnoid hemorrhage (bleeding from a ruptured aneurysm), and other problems.
• Doppler fetal monitors, although usually not technically -graphy but rather sound-generating, use the Doppler effect to detect the fetal heartbeat for prenatal care. These are hand-held, and some models also display the heart rate in beats per minute (BPM). Use of this monitor is sometimes known as Doppler auscultation. The Doppler fetal monitor is commonly referred to simply as a Doppler or fetal Doppler. Doppler fetal monitors provide information about the fetus similar to that provided by a fetal stethoscope.