Pallor of the fingers and pressure differences on the hands
The arteries of the arms are affected by atherosclerosis much less frequently than the arteries of the legs, so the indications for their examination are different. The most common is Raynaud's syndrome: attacks of paleness, then blueness and redness of the fingers in the cold or with excitement. The objective of the study is to distinguish primary Raynaud's syndrome, in which the vessels are structurally unchanged and we are talking only about vasospasm, from secondary, which develops with systemic scleroderma, vasculitis and other diseases with real damage to the vascular wall. The tactics in these cases are fundamentally different.
The second indication is a difference in blood pressure between the arms of more than 15–20 mmHg. Art. It indicates stenosis or occlusion of the subclavian artery, usually on the left. Severe narrowing before the origin of the vertebral artery leads to vertebral-subclavian steal syndrome: when the arm is loaded, blood flows from the brain through the vertebral artery in the opposite direction, causing dizziness and darkening of the eyes. Retrograde blood flow in the vertebral artery is clearly visible during examination.
Some indications are compression syndromes of the upper thoracic outlet, in which the vessel is compressed by an additional rib or muscle in a certain position of the arm and is detected only by positional tests, as well as mapping of vessels before the formation of an arteriovenous fistula for hemodialysis. Examination of both hands is mandatory: comparison of the sides is the main diagnostic technique here.
What does duplex scanning show?
The method combines conventional ultrasound imaging of a vessel with analysis of the blood flow in it. The wall of the artery and vein, the thickness of the intima-media complex, atherosclerotic plaques with an assessment of their structure and the degree of narrowing of the lumen, blood clots, aneurysms, tortuosity and pathological anastomosis are visible.
Spectral analysis translates this into numbers: peak systolic velocity, end-diastolic velocity, resistance indices. They are used to calculate the percentage of stenosis - an indicator that determines whether conservative treatment is sufficient or intervention is required.
Functional tests
Some vascular pathology appears only during exercise. Compression tests detect thrombosis: a healthy vein is completely compressed by the sensor, a thrombosed one is not. The Valsalva maneuver shows the incompetence of the venous valves and reflux underlying varicose veins.
Positional tests are used when compression syndromes are suspected, when a vessel is compressed by muscles, ligaments or an additional rib in a certain position of the limb. At rest the picture is normal.
Advantages over other methods
Duplex scanning does not require contrast or radiation, so it can be repeated as often as necessary, including in cases of renal failure and allergies to iodine-containing drugs, where contrast angiography is contraindicated.
Operator-dependent method: the result depends significantly on the experience of the doctor and the quality of the device. Therefore, when making fundamental decisions, for example, before vascular surgery, the study is often repeated or supplemented with computed angiography.