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It may use microphones, accelerometers, and multifrequency ultrasonic transducers. It does not use any radiation and is completely free of any side effects. ACG also facilitates blood flow analysis as well as the detection of obstructions in cerebral blood flow (from cerebral embolism) or bleeding (from cerebral hemorrhage).
As the blood moves into the aortic arch, the area with the highest velocity tends to be on the inner wall. Helical flow within the ascending aorta and aortic arch help to reduce flow stagnation and increase oxygen transport. [4] As the blood moves into the descending aorta, rotations in the flow are less present.
For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. [18] There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry. [19]
An accelerometer measures proper acceleration, which is the acceleration it experiences relative to freefall and is the acceleration felt by people and objects. [2] Put another way, at any point in spacetime the equivalence principle guarantees the existence of a local inertial frame, and an accelerometer measures the acceleration relative to that frame. [4]
An estimate of the aortic cross-sectional area is calculated from a function of age, weight and height. The cross-sectional area is adjusted to give more accurate cardiac output and renamed to aortic constant (AC). The product of stroke distance and aortic constant gives stroke volume (how much blood was ejected from a heartbeat into the arteries).
Prior to opening of the aortic valve, the red blood cells (erythrocytes) assume a random orientation (there is no blood flow in the aorta). When the electric current is applied from the outer electrodes, the current must circumference these red blood cells, therefore resulting in a higher voltage measurement, and thus, a lower conductivity.
With the ability to ascertain data on the blood flow to vital organs such as the heart and the brain, doctors are able to make quicker and more accurate choices on treatment for patients. Nuclear medicine has been leading perfusion scanning for some time, although the modality has certain pitfalls.
The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known: Amount of marker substance taken up by the organ per unit time; Concentration of marker substance in arterial blood supplying the organ; Concentration of marker substance in venous blood leaving the organ