The English term 'echocardiography' means a noninvasive diagnostic procedure that uses ultrasound to study to structure and motions of the heart
Echocardiography uses sound waves to make images of the heart. These images can show if there are any abnormalities of the heart valves.
Because ultrasonography uses high frequency sound waves, and not x rays or other forms of radiation , there are very few risks associated with its use
It would be perfectly acceptable to say highly risky activities, however, the most common phrasing would be high risk activities.
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