Ultrasound Doppler ultrasonography of the venous system

Acoustic signals from arteries and veins differ significantly: if the former have a pulsating high tone, synchronous with heart contractions, then venous noise is characterized by a low unmodulated sound, reminiscent of the surf and changing in intensity depending on the stage of the respiratory cycle. Graphic registration of phlebo-Doppler patterns on conventional devices is not possible due to the low signal power and imperfection of the inertial systems of recorders. Spectrographic analysis allows for clear recording of venous flow.

• When examining the circulation in the ophthalmic vein, the subject lies on his back with his eyes closed, the head on a small pillow. The gel is applied to the inner corner of the eye. The ultrasound sensor is installed at the site of gel application at an angle of 10% to the projection of the sagittal sinus and at an angle of 20% to the coronary suture. By slightly shaking the probe with very slight pressure on the eyeball, the signal from the ophthalmic vein is searched for and recognized. The location is usually facilitated by preliminary determination of the signal from the supratrochlear artery, in the immediate vicinity of which the desired vein is usually located. The same procedure is performed in a symmetrical area on the opposite side. The probe pressure should be minimal (weaker than when locating the ophthalmic artery) to avoid compression of the vein being located, which is manifested by the disappearance of the blowing signal.
• The signal from the jugular veins is easiest to obtain in the lower third of the neck, slightly anterior to the lateral surface of the sternocleidomastoid muscle in the region of the supraclavicular triangle. Searching for and recognizing the signal from the jugular vein is easier after receiving a pulsating signal from the common carotid artery: a slight outward displacement of the sensor with reduced pressure on the skin most often allows recording a characteristic blowing signal that has a direction opposite to the common carotid artery - from the cranial cavity, downwards from the isoline.
• Determining the signal from the subclavian vein usually does not cause difficulties. The location of the subclavian vein allows for its error-free puncture (for insertion of a venous catheter and subsequent infusion therapy). This is especially important in cases of anatomical and physiological features in the patient's neck. First, by placing the sensor 0.5 cm below the clavicle in its outer third, a pulsating signal from the subclavian artery is identified. Then, by slight changes in the angle of inclination and the degree of compression, a characteristic blowing noise of the subclavian vein is found. Such a location and degree of compression of the sensor are found, at which the signal from the subclavian vein is maximal - it is in this place and at this angle that the needle is inserted for catheterization of the subclavian vein.
• The signal from the veins of the vertebral plexus is located approximately in the same area as the flow signal from the vertebral artery - slightly below and medial to the mastoid process.

The most important aspect of the semiology of cerebral venous circulation is the assessment of blood flow in the orbital veins. In healthy people, blood from the deep and superficial veins of the face is directed through the maxillary vein to the medial edge of the orbit and through the orbital vein enters the cavernous sinus. The internal carotid artery passes through the cavernous sinus - it is located in the center of the venous lacuna, the wall of which is adjacent to the adventitia of the artery. The walls of the venous sinus are fixed and inflexible, so a change in the caliber of the internal carotid artery when it pulsates in the lumen of the sinus changes its volume, which stimulates the outflow of venous blood. Normally, a much more powerful flow signal through the ophthalmic artery in the orthograde direction from the cranial cavity completely or partially suppresses a much weaker venous signal, which also has the opposite direction (towards the cavernous sinus). Therefore, in most healthy people, periorbital Doppler ultrasound only records arterial flow from the supratrochlear and supraorbital vessels in the absence of a venous component.

Non-physiological venous outflow from the cranial cavity has the following signs:

• symmetrical or asymmetrical signal from the orbital veins of moderate intensity;
• increased signal when locating the vertebral plexus area in a lying patient, i.e. outflow occurs both through the jugular veins and through the vertebral plexus.

It should be taken into account that such variants of phlebocirculation can be present both in practically healthy people and in patients with various conditions, one way or another including a component of vegetative-vascular dystonia of the venous type. In addition, if the first identified asymmetry of the linear velocity of blood flow in the cerebral arteries is also noted during subsequent examinations, then the signs of venous dyscirculation are very variable and depend on a number of factors, primarily positional ones. This is especially clearly demonstrated in clinical and instrumental monitoring of patients with signs of venous encephalopathy, manifested in the morning hours. As shown by some studies with monitoring using ultrasound Dopplerography before and after sleep, signs of moderate or severe venous discirculation in the form of non-physiological redistribution of outflow and/or obvious retrograde flow along the orbital veins are present in the vast majority of patients if repeated ultrasound Dopplerography is performed in bed before the awakened patient moves to a vertical position. It turned out that it is at this time that both clinical manifestations (headache, ringing, noise in the ears, swelling under the eyes, nausea) and patterns of ultrasound Dopplerography (sharp venous discirculation along the orbital artery and/or vertebral veins) occur. 5-10 minutes after getting up and performing hygienic procedures, the patients' well-being significantly improves in parallel with a clear decrease in signs of venous discirculation.

If the above-mentioned patterns of moderate venous dysgemia are variable and inconstant, there are a number of pathological conditions in which the signs of venous outflow disorders are pronounced and persistent. These are focal brain lesions, especially with localization in the anterior and middle cranial fossae, and traumatic subdural hematoma. The triad of ultrasound signs of this pathology, in addition to the displacement of midline structures and hematoma echo, includes the sign of a sharp increase in retrograde flow along the ophthalmic vein on the side of the meningeal blood accumulation, which we described for the first time. Taking into account the above-mentioned patterns allows us to establish the presence, side of the lesion and the approximate volume of the subdural hematoma in 96% of cases.

A fairly pronounced lateralized retrograde flow along the ophthalmic vein is also noted in otogenic and rhinogenic abscesses, hemispheric tumors of the parietal-temporal localization.