Lecture 27: Clinical Focus: Ultrasound/Transthoracic Echocardiography Flashcards
What is an ultrasound?
A mechanical wave of compression and rarefaction
What does an ultrasound require?
A medium (usually fluid)
What is the frequency of an ultrasound?
Above audible range, >20,000Hz
What is the speed of sound in biological tissues?
1540m/sec
What things do not transmit ultrasound?
Air and bone
Why does lots of the energy from the transducer not come back?
Absorbed by tissues
What do white and black ultrasound images mean?
Strong reflection is white images and weak reflection is black images
What is the negative of the left atrial appendage?
Collects thrombi
What does a spontaneous grey contrast/smoky appearance mean?
Low blood flow state, consistent with thrombus formation
What does it mean when there is black surrounding the heart (& white strands)?
Pericardial effusion - fibrin
