Subclavian Artery Thrombosis

Excerpt

Subclavian artery thrombosis is a condition characterized by the formation of a blood clot within the subclavian artery, a large blood vessel located in the shoulder region. Thrombosis can significantly reduce blood supply to the vessel's distribution area, often the ipsilateral upper extremity. Rarely, the condition can affect the brain and heart. Complete stenosis from subclavian artery thrombosis may be considered a medical emergency, potentially causing limb loss and stroke if not treated promptly.

Symptoms of subclavian artery thrombosis may include pain, numbness, weakness, or coolness in the affected limb, particularly during physical activity or with certain arm positions. In severe cases, individuals may experience ischemia symptoms, such as skin color changes or even gangrene. Subclavian artery thrombosis can occur due to various factors, including atherosclerosis, hypercoagulable states, trauma, or certain medical procedures.

A combination of thorough clinical evaluation and imaging studies, particularly Doppler ultrasound, computed tomography angiography (CTA), and magnetic resonance angiography (MRA), is critical to diagnosis. Treatment aims to restore circulation in the affected artery and prevent complications. Nonsurgical and surgical interventions are recommended, depending on the extent of thrombosis and the patient's risk factors. These interventions include anticoagulant therapy and thrombolytic therapy, thrombectomy, and angioplasty with stent placement. Notably, the treatment is graded depending on the severity and after assessing the risk of potential complications. Overall, subclavian artery thrombosis is a serious condition requiring prompt and appropriate management to prevent long-term complications and preserve limb function.

Subclavian Artery Anatomy

The subclavian artery originates from the brachiocephalic trunk on the right side and the aortic arch on the left side. This artery supplies the upper limb, neck, and brain, coursing through the chest from its origin and traversing the thoracic outlet beneath the clavicle and over the 1st rib before reaching the axilla. Along its path, the subclavian artery gives rise to several branches, each serving distinct anatomical areas and functions.

The subclavian artery consists of 3 parts. The 1st part extends from the subclavian artery's origin to the anterior scalene muscle's medial border. The 2nd part lies posterior to the anterior scalene muscle. The 3rd part courses from the anterior scalene's lateral border to the 1st rib's lateral border. The subclavian artery's branches include the vertebral artery, internal mammary artery (IMA), thyrocervical trunk, costocervical trunk, and dorsal scapular artery. On the left side, all branches except the dorsal scapular artery arise from the 1st part. On the right side, the costocervical trunk typically originates from the 2nd part.

The vertebral artery emanates from the 1st part of the subclavian artery and ascends through the cervical vertebrae's transverse foramina to supply the brain and spinal cord. When the subclavian artery is narrowed or blocked, blood from the contralateral vertebral artery or other intracranial collaterals can flow retrogradely through the vertebrobasilar system to help maintain brain perfusion. This collateral circulation can mitigate the risk of cerebral ischemia and stroke in individuals with subclavian artery stenosis, providing a vital compensatory mechanism to preserve brain function.

The IMA, also called the "internal thoracic artery," descends along the chest wall's inner surface and provides blood to the chest wall and breasts. This artery is often involved in coronary artery bypass grafting (CABG). The thyrocervical trunk divides into the inferior thyroid, transverse cervical, and suprascapular arteries, which supply blood to the thyroid gland, neck muscles, and shoulder region, respectively. The costocervical trunk distributes blood to the upper intercostal spaces, deep neck muscles, and superior spinal cord portions. The dorsal scapular artery, arising either separately or as a transverse cervical artery branch, nourishes the shoulder girdle and back muscles. The subclavian artery transitions into the axillary artery after passing the 1st rib's lateral border.

The subclavian artery supplies vast areas in the head, neck, and upper limb. Knowledge of this artery's anatomy is vital for diagnosing and treating conditions like subclavian artery thrombosis and conducting surgical procedures in the shoulder, arm, and neck regions.