Acoustic shadowing is the artifact caused by calcified structures like the mitral annulus, resulting in attenuation or loss of echoes from structures posterior to the calcification. The calcification absorbs or reflects the ultrasound waves, preventing them from reaching deeper structures and causing a "dropout" or dark shadow behind the calcified area.
Reverberation involves repeated reflections creating multiple echoes. Side lobe artifacts arise from off-axis beams. Ring-down artifacts result from resonance in fluid or gas bubbles, not calcifications.
This artifact is explained in the "Textbook of Clinical Echocardiography, 6e", Chapter on Ultrasound Artifacts【20:75-80†Textbook of Clinical Echocardiography】.QUESTION NO: 134
What is the range of the aortic valve area in normal adults?
A. 1 - 2 cm2
B. 3 - 4cm2
C. 5 - 6cm2
D. 7- 8cm2
Answer: B
Comprehensive and Detailed Explanation From Exact Extract:
The normal aortic valve area (AVA) in adults typically ranges from 3 to 4 cm². This measurement is important for assessing aortic stenosis severity; values below this range suggest valve narrowing.
AVA values of 1-2 cm² indicate mild to moderate stenosis, while less than 1 cm² reflects severe stenosis. Larger areas like 5-6 or 7-8 cm² are not physiologically typical.
This normal range is documented in the "Textbook of Clinical Echocardiography, 6e", Chapter on Aortic Valve Anatomy and Function【20:360-365†Textbook of Clinical Echocardiography】.
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