Question

Color Doppler ultrasound devices are often used to assess the health of the fetal heart during pregnancy. During a fetal ultrasound exam, a transducer placed against the expectant mother's abdomen transmits ultrasound waves with a frequency of 3.500 MHz and receives the Doppler shifted echo from the fetal heart.

(a)

If the echo received from the fetal heart by the transducer has a frequency of 3.498 MHz and 3.503 MHz from the left and right ventricles, respectively, what is the speed (in cm/s) of the blood flow in these two chambers of the fetal heart? The blood in the left ventricle flows away from the transducer while the blood in the right ventricle flows toward the transducer. Use v = 1,500 m/s for the speed of sound in tissue.

left ventricle ____________ cm/s

right ventricle ___________ cm/s

(b)

What if? The Doppler ultrasound transducer is now applied to an adult patient that is feared to have deep vein thrombosis, a blood clot forming in a deep vein, most often in the leg. Operating at the same frequency, what frequency echo (in MHz) would correspond to a "normal" blood flow in the common femoral vein of 4.00 cm/s toward the transducer? (Round your answer to at least five decimal places.)

___________ MHz

Answer 1