Causes of Subclavian Vein Thrombosis

Venous thrombosis can occur in many places, such as subclavian vein thrombosis, which often causes swelling of the upper limbs and pain. Sometimes the skin may turn purple and it may cause limb dysfunction. There are many causes of subclavian vein thrombosis, the most important of which is the primary cause. There are also many secondary causes.

Causes of Subclavian Vein Thrombosis

1. Primary cause of the disease The primary cause of the disease is outside the blood vessels. It is usually caused by changes in the position of the upper limbs or strong activities, which cause blood vessel compression, with or without thoracic outlet compression signs caused by anatomical abnormalities. For example, when the subclavian vein passes through the costoclavicular triangle, it is compressed by the costoclavicular ligament, subclavian muscle, anterior scalene muscle and prominent scalene muscle tubercle. When the upper limbs perform strong activities (swimming, climbing, weightlifting, softball and tennis, etc.), or due to certain occupations causing unfamiliar movements of the upper limbs, the subclavian vein can suffer repeated injuries and thickening of the endothelium, eventually leading to thrombosis. This is traditionally called Paget-Schroetter syndrome, also known as "effort thrombosis".

2. Secondary causes of the disease There are many secondary causes, such as the insertion of catheters and wires into blood vessels, injection of irritating drugs, etc. After intravenous catheterization, about 1/3 of patients may develop thrombosis, of which 1% to 5% have clinical symptoms. In addition, there are oral contraceptives for pregnancy during heart failure, coagulation and fibrinolytic dysfunction, arteriovenous fistula for hemodialysis, etc. Other causes are extravascular, such as cancer, radiation therapy, first rib or clavicle fractures, etc.

Clinical manifestations can occur in men and women of any age. Secondary cases often have traceable causes. Paget-Schroetter syndrome is more common in young and middle-aged men. Two-thirds of the lesions occur in the right upper limb, which may be related to the greater use of force on the right upper limb. 4/5 of the patients have a history of frustration 24 hours before the onset of the disease, such as strong upper limb activities or long-term upper limbs in unfamiliar postures. About 1/10 of the patients may not have any inducement, but only find it when they wake up in the morning after a night's sleep.

The four main symptoms are upper limb swelling, pain, skin cyanosis and superficial varicose veins. Swelling of the upper limbs is the earliest symptom, extending from the fingers to the upper arms and covering the entire upper limbs, with the proximal side being more severe. Pain may occur simultaneously with swelling, or may only manifest as soreness and swelling, which is aggravated by upper limb movement. Sometimes, a cord-like, tender thrombosed vein can be palpated. About 2/3 of patients have venous congestion, and the affected limbs become purple or bluish purple. Superficial varicose veins usually form after 1 to 2 days and are most obvious in the shoulders and upper arms. For most patients, acute symptoms such as swelling and pain may be relieved on their own within a few days or weeks, but complete recovery is still difficult to achieve. About two-thirds of patients have residual lesions, which manifest as varying degrees of swelling and soreness or swelling and pain after activities.