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The reflected ultrasound is received by the probe, transformed into an electric impulse as voltage, and sent to the engine for signal processing and conversion to an image on the screen. The depth reached by the ultrasound beam is dependent on the frequency of the probe used. The higher the frequency, the lesser the depth reached. [9]
The ultrasound catheter tip is slid in over the guidewire and positioned, using angiography techniques so that the tip is at the farthest away position to be imaged. The sound waves are emitted from the catheter tip, are usually in the 20-40 MHz range, and the catheter also receives and conducts the return echo information out to the external ...
The risk of deep vein thrombosis can be estimated by Wells score.. Lower limbs venous ultrasonography is also indicated in cases of suspected pulmonary embolism where a CT pulmonary angiogram is negative but a high clinical suspicion of pulmonary embolism remains. [1]
Congenital stenosis of vena cava is a congenital anomaly in which the superior vena cava or inferior vena cava has an aberrant interruption or coarctation. In some cases, it can be asymptomatic, [ 1 ] and in other cases it can lead to fluid accumulation and cardiopulmonary collapse.
For example, in portal hypertension, there is an abnormal portal venous flow where it flows away from the liver (hepatofugal flow) instead of the normal flow towards liver (hepatopetal flow). In jugular venous pressure waveform of the internal jugular vein, the retrograde "a" waveform is a normal flow due to right atrium contraction. Both ...
Inferior vena cava syndrome (IVCS) is a very rare constellation of symptoms resulting from either obstruction or stenosis of the inferior vena cava. It can be caused by physical invasion or compression by a pathological process, or by thrombosis within the vein itself. It can also occur during pregnancy. Symptoms including high venous pressure ...
The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins , usually at the level of the fifth lumbar vertebra .
A JVP waveform. The jugular venous pulsation has a biphasic waveform. The a wave corresponds to right atrial contraction and ends synchronously with the carotid artery pulse. The peak of the 'a' wave demarcates the end of atrial systole. The x descent follows the 'a' wave and corresponds to atrial relaxation and rapid atrial filling due to low ...