Doppler Ultrasound of the Carotid Arteries
The arteries that supply the brain with blood pass through the cervical region (neck). At this level they are easy to explore with ultrasound. Two internal carotid arteries (right and left) irrigate the most part of the brain in the anterior portion and the two vertebral arteries (right and left) supplying the rear portion of the brain, but also cerebellum and the brain stem (the connecting portion of the nervous system spinal cord and brain). With the help of ultrasound, can be visualized and explored in the cervical region including the common carotid arteries, external carotid arteries and subclavian arteries.
Ultrasonic exploration method is based on the device receiving ultrasound echoes on which the anatomical structures explored they emit from their contact with the waves that it issues probe device. Ultrasounds are used waves from the ultrasound, vibration with a frequency greater than some sounds (ultrasound inaudible to the human ear).
Ultrasounds are emitted and received by the ultrasound probe apparatus, the probe containing piezoelectric crystals that vibrate in contact with a weak electrical current. Anatomical structures that are sent to ultrasound can absorb them (for example: soft structures, fluid or acids) may reflect, sending back echoes, or disperse them. The machine analyzes the ultrasound echoes from the anatomical structures and creates a real-time image of these structures. In our case, we can see the blood vessels (arteries and veins), we can see the walls of these vessels, we can see also the deposition of cholesterol on artery walls and can see if the blood vessel is narrowed (stenosis) or occluded by clots blood. Also, it can be seen that the deposition of fats and cholesterol on the arterial walls are at high risk in the form of their blood clots which may block arteries and thus, can result in stroke. These images are two-dimensional ultrasound.
The device can analyze also the echoes emitted by the moving column of blood through the arteries and veins. On the basis of this analysis lie an effect / phenomenon described in the nineteenth century by the Austrian physicist Christian Doppler (frequency variation of a wave emitted or reflected by an object moving against a stationary receiver). Therefore, the method is called the Doppler Effect. By means of this method it can reveal the blood flow rate, manner of flow of blood through the arteries (smooth flow, laminar flow with eddies, vortices, that is turbulent). The unit emphasizes the flow of blood through the sounds and images. The images are either in the form of a graph of the rates or in the form of colors occurring in the image of the artery, and directly shows the manner in which the blood flows.
Doppler ultrasound of the carotid vessels can show the status of the vessels, degree of atherosclerosis and risk of stroke, stenosis (narrowing) of the vessels or occlusion (blockage) of these vessels, of any dangerous plaque, the risk of stroke, or if there are thrombi (clots) in the arteries or if there is a dissection (splitting) of the blood vessel wall. Doppler ultrasound may identify either the risk of stroke or even the source, arterial cause of a stroke. Thus, this method allows orientation to medication therapy or sometimes to surgery (artery enlargement through surgery) or through catheter intervention (balloon probe is inserted in the artery, the balloon is inflated, it widens the artery and then allow there for a mesh, which is a stent that prevents vessel ceiling).
If there is thickening of the arteries wall in the neck level or plaque is highlighted in these walls, this is a warning for the vessels of the heart, coronary arteries, which may also present similar changes when there is risk of myocardial infarction.
In conclusion, Doppler ultrasound of the carotid arteries is simple, without dangers for the patient, and which can give a lot of information about the patient’s arteries and about how blood flows through the arteries, highlighting the risk of stroke or cause of a cerebral stroke or sounding the alarm about the risk of myocardial infarction. This method is very useful for determining appropriate treatment, medication and sometimes surgery or interventions.