Upper Extremity, Neck, and Central Thoracic Veins

Anatomy

Veins of the Neck

The internal jugular veins (IJV) are the largest veins of the head and neck. These valveless veins begin at the sigmoid fossa of the skull and anastomose with the subclavian veins at the base of the neck, behind the proximal head of the clavicle. There is almost always a valve in the IJV at this junction. Within the middle and lower neck the IJV lies within the carotid sheath anterior and slightly lateral to the carotid artery and beneath the sternocleidomastoid muscle (see Fig. 2-41 ). One IJV tends to be larger or “dominant” in most patients, usually the right. Important tributaries of the IJVs include the inferior petrosal sinuses (venous blood from the pituitary) at the jugular foramen, and the superior and middle thyroidal veins in the neck ( Fig. 7-1 ). The inferior thyroidal vein is usually a single structure that drains vertically into the left brachiocephalic vein.

The external jugular veins (EJVs) are much smaller in size than their internal counterparts (see Fig. 7-1 ). The EJVs drain soft tissue structures of the face, scalp, and neck. Superficial in location, these veins are frequently visible as they pass over the upper sternocleidomastoid muscle and travel in an oblique course toward the supraclavicular fossa. The EJVs enter the subclavian veins just lateral to the IJVs. Additional drainage of the head and neck is provided by the vertebral veins, which also drain into the subclavian veins.

Key Collateral Pathways

Obstruction of one IJV results in drainage through the opposite vein. Obstruction of both IJVs is usually well tolerated due to the numerous potential collateral drainage pathways. These include the external jugular, vertebral, inferior thyroidal, and muscular veins of the neck.

Veins of the Upper Extremities

The veins of the upper extremities are divided into superficial and deep systems. From the hand to the shoulder, the superficial veins are the major drainage pathway. At the shoulder the deep veins become the primary drainage route. This is different from the venous anatomy of the lower extremities, where the deep veins are the dominant drainage throughout.

The superficial veins of the forearm are the cephalic along the anterior radial edge, the basilic along the posterior ulnar edge, and the median along the anterior aspect in the midline ( Fig. 7-2 ). At the antecubital fossa just below the elbow joint, the cephalic vein sends a branch, the median cubital vein, obliquely across to join the basilic vein, which swings anteriorly in the upper third of the forearm to meet this branch. The median vein of the forearm drains into the median cubital vein.

In the upper arm, the cephalic vein lies in the groove between the biceps and brachialis muscles. At the shoulder, the cephalic vein passes between the pectoralis and deltoid muscles, diving over the medial edge of the pectoralis minor muscle to join the deeper axillary vein. There are no critical arterial or neural structures near the cephalic vein. The basilic vein ascends along the medial border of the biceps muscle, superficial to the brachial fascia, accompanied by only a few small superficial nerves. The brachial artery, veins, and associated major nerves lurk below the brachial fascia. At the junction of the distal and middle thirds of the upper arm, the basilic vein pierces the brachial fascia to join the deep (brachial) veins. The basilic vein becomes confluent with the brachial veins at the lower border of the teres major muscle to form the axillary vein. The basilic vein is easily identified in the upper arm as the largest single, most superficial medial draining vein.

The deep veins of the arm are small paired structures that parallel their associated namesake arteries ( Fig. 7-3 ). Predictably, the deep veins of the forearm are the ulnar, interosseous, and radial veins. These drain into the paired brachial veins at the level of the antecubital fossa. In the upper arm, the brachial veins are closely related to the brachial artery and the median and radial nerves. At the lateral border of the teres major muscle, the brachial veins fuse with the basilic vein to form the axillary vein. Up until this point, the deep veins are smaller in size than the superficial veins. However, from the axillary vein centrally the deep veins assume dominance. The axillary vein lies slightly inferior and anterior to the axillary artery. At the lateral edge of the first rib, the axillary vein becomes the subclavian vein. This vein passes between the first rib and the clavicle to combine with the IJV at the thoracic inlet to form the brachiocephalic veins. Of all the upper extremity veins, only the subclavian vein is consistently valveless.

Key Collateral Pathways

The venous drainage of the upper extremities is rich with potential collateral pathways. Because of the multiplicity of veins in the arm, occlusion of a basilic or brachial vein is usually well tolerated. Occlusion of an axillary or subclavian vein results in collateral flow through muscular and superficial veins about the shoulder, scapula, and chest wall. Dilated subcutaneous veins over the upper chest and shoulder are frequently visible in patients with occluded central veins. Potential decompressive pathways include the ipsilateral IJV, the ipsilateral intercostal veins, and the contralateral jugular or subclavian veins ( Fig. 7-4 ).

Central Thoracic Veins

Blood from the upper extremities and the head returns to the heart through the brachiocephalic (or innominate) veins and the superior vena cava (SVC) ( Fig. 7-5 ). The right brachiocephalic vein is a short (2- to 3-cm) structure that has a vertical trajectory into the SVC. The left brachiocephalic vein, fully 2-3 times longer than the right, crosses from the left side of the mediastinum anterior to the great vessels to join the right brachiocephalic vein. This defines the origin of the SVC. Important tributaries of the brachiocephalic vein include the internal mammary, vertebral, pericardiophrenic, and the first intercostal veins. On the left, the inferior thyroidal vein drains into the superior aspect of the midpoint of the brachiocephalic vein.

The left brachiocephalic vein crosses the midline to join the right in more than 99% of normal individuals. In less than 1% of patients without congenital heart disease, the left brachiocephalic vein does not anastomose with the right but drains into the coronary sinus through a second, left-sided SVC ( Fig. 7-6 ). This anomaly is observed in 4%-5% of patients with congenital heart disease.

The SVC is generally 6-8 cm in length, and up to 2 cm in diameter. The main tributaries of the SVC are the brachiocephalic veins and the azygos vein. The SVC generally enters the pericardium below the orifice of the azygos vein. In more than 99% of individuals, this vessel is single, right-sided, and drains into the right atrium.

The azygos and hemiazygos veins are posterior mediastinal structures that originate at the L1-L2 level ( Fig. 7-7 ). The azygos vein ascends anterior to the thoracic spine to the right of the midline, while the hemiazygos vein lies slightly to the left of the midline anterior to the spine. Both veins receive blood from ascending lumbar, intercostal, subcostal, esophageal, and bronchial veins. The hemiazygos vein crosses anterior to the spine at the level of the T8 vertebral body to join the azygos vein. The azygos vein continues cephalad to the level of the T4 vertebral body, where it passes anteriorly over the right hilum to empty into the SVC. The accessory hemiazygos vein is a small, left-sided tributary of either the azygos or hemiazygos vein that drains the upper (through T8) intercostal veins. This vein will sometimes empty anteriorly and superiorly into the left brachiocephalic vein, in which case it can be visualized along the lateral border of the proximal descending thoracic aorta.

Key Collateral Pathways

Occlusion of a brachiocephalic vein results in obstruction of flow from both the ipsilateral arm and neck. Facial swelling on the side of the occlusion is rare as long as the contralateral IJV is patent. The venous blood from the arm may drain across the back, chest, and neck via deep and superficial collaterals to the opposite jugular, subclavian, and brachiocephalic veins. The superficial chest wall veins such as internal mammary and intercostal veins may also serve as collateral drainage pathways. These veins drain into the azygos vein on the right and hemiazygos vein on the left, or may continue down the abdominal wall to the inferior epigastric veins. Pericardial and phrenic veins may also be recruited as collateral drainage pathways.

The level of occlusion of the SVC determines which collateral pathway will be dominant. When occlusion is above the azygos vein, the collateral drainage involves primarily the chest wall and intercostal veins, emptying into the azygos system. The direction of flow within the azygos veins remains toward the SVC. Some drainage through the pericardial and abdominal wall veins may be present as well. When the occlusion is localized below the azygos vein, flow reverses in this vein with drainage into the inferior vena cava (IVC) ( Fig. 7-8 ). Chest wall and pericardial collaterals may also develop. Occlusion of the SVC above and below the azygos veins results in azygos and hemiazygos drainage into the IVC, as well as extensive chest wall and pericardial collateral veins.

Imaging

The superficial veins of the neck and upper extremity can be readily imaged with ultrasound. When evaluating a patient for upper extremity central venous thrombosis, the neck as well as the upper extremity veins should be studied, because the jugular veins are frequently involved. Gray scale imaging with compression and Doppler with color flow can provide information about venous patency and direction of flow ( Fig. 7-9 ). The central veins such as the brachiocephalic veins and SVC cannot be directly imaged satisfactorily with external ultrasound transducers owing to the surrounding bone and lung. The patency of the central vessels can be inferred by studying subclavian vein and IJV Doppler waveforms at rest and in response to respiration and Valsalva maneuver. However, the impact of central stenoses on flow in the more peripheral veins has not been carefully worked out and may be masked by a well-developed collateral network. If, for some reason, ultrasound examination of the intrathoracic veins is strongly desired, then a transesophageal study is required.

Contrast-enhanced computed tomography (CT) is an excellent modality for evaluation of the jugular, proximal subclavian, brachiocephalic, and central veins, as well as the surrounding structures. The veins from the forearm to the axilla are difficult to image with CT. The advantages of this modality are the ability to map out collateral pathways, such as superficial chest wall veins in SVC obstruction, as well as revealing extrinsic causes of venous obstruction. Injection of contrast into the upper extremity opposite the side of interest followed by a saline “chaser” for indirect CT venography can limit streak artifact from dense contrast. A delayed scan after the initial contrast injection is often useful to obtain opacification of all veins. Direct CT venography is performed with dilute contrast injected into the arm of interest during image acquisition. For all CT venography, careful postprocessing is useful when tracing collateral pathways and determining the etiology of extrinsic compression.

Magnetic resonance venography (MRV) is an excellent cross-sectional modality for evaluating the upper extremity, neck, and central veins ( Fig. 7-10 ). Suppression of signal from background structures results in images that are easy to view, in comparison to CT in which bone and other tissues can obscure the veins. The most robust techniques involve gadolinium-enhanced acquisitions, preferably with subtraction of the enhanced arteries. The side of injection of contrast is not an issue with this technique, except that concentrated gadolinium may result in signal loss due to dominance of T2 shortening effects (see Fig. 3-16 ). This is easily solved by sequential acquisitions over several minutes, during which time the gadolinium becomes diluted. Conventional two-dimensional time-of-flight (2-D TOF) techniques have also been used with great success, although multiple acquisitions with careful orientation of the slices and saturation bands are necessary to image all of the veins (e.g., axial slices with inferior saturation for the jugular veins and SVC, but sagittal slices with medial saturation slabs for the brachiocephalic and subclavian veins). MRV of the veins of the forearms can be used for planning surgical dialysis access, but ultrasound and conventional venography are more readily available.

Although MRV is excellent for visualizing the vein lumen, the surrounding structures are not well seen. At a minimum, conventional anatomic T1-weighted images are necessary to evaluate the adjacent soft tissues.

Arm venography is a simple, quick procedure for evaluation of the upper extremity and central veins. The IJVs are not routinely studied with this technique. For arm venography, an 18- to 20-gauge intravenous (IV) line should be started in a hand or forearm vein. When using existing IV access, test it first to ensure that it is patent and in a vein. Injection of the antecubital vein or upper arm cephalic vein may fail to opacify the basilic, brachial, and proximal axillary veins. Two or three 20-mL syringes of dilute contrast (20%-30% iodine) are injected by hand. Carbon dioxide gas is an excellent alternative contrast agent, except in patients with dialysis access grafts or fistulas. A tourniquet at the axilla enhances filling of deep and superficial veins. The hand should be in anatomic position (palm up) with the arm slightly abducted. In large patients, compression by the chest wall soft tissues can cause pseudostenosis of the veins in the medial aspect of the upper arm ( Fig. 7-11 ). Both spot films and digital subtraction images are satisfactory for the arm veins. Digital subtraction is usually required to adequately visualize the brachiocephalic veins and SVC. Unopacified inflow from other central veins should not be mistaken for thrombus or other filling defects. Bilateral injections can be performed to evaluate central processes (see Fig. 7-5 ). One of the major advantages of conventional arm venography is that there is an option to proceed directly to an intervention if an amenable abnormality is found.

Upper Extremity Venous Thrombosis

Acute thrombosis of a single peripheral upper extremity vein rarely results in arm swelling, but patients may have pain and tenderness over the involved vein. A common etiology is intravenous injection of medication or illicit drugs. The treatment is oral antiinflammatory agents and local measures such as heat packs. Thrombosis of central veins such as the axillary, subclavian, or brachiocephalic veins may result in swelling and cyanosis of the arm, especially when the limb is dependent. Frequently, patients report the first symptom as a ring or wristwatch feeling tight. Acute thrombosis may also be locally painful, possibly due to the expansion of the vein by thrombus or tense edema of the extremity. When the jugular vein is involved patients may complain of neck stiffness, tenderness, or a sense of swelling of the face on the affected side. Facial swelling is rarely a symptom of unilateral (or even bilateral) jugular vein thrombosis in a patient with patent central veins. Phlegmasia (alba or cerulea dolens) is also extremely rare in the upper extremity. Pulmonary embolization from the upper extremity is thought to occur in up to 15%-30% of cases, but is often asymptomatic.

Chronic occlusion of the small superficial upper extremity veins produces a hard, cordlike structure, but is usually otherwise innocuous. Chronic central thrombosis is suggested by the presence of well-developed superficial chest wall collateral veins. Patients may complain of arm swelling, particularly with use of the limb, but many are asymptomatic.

Central venous catheterization is the most common underlying etiology of upper extremity and jugular thrombosis ( Box 7-1 ). Reported rates of pericatheter thrombus range from 3% to 60% with chronic indwelling subclavian venous catheters, although fewer (5%-10%) are symptomatic ( Fig. 7-12 ). Many factors influence the incidence of this complication in specific patient populations, such as catheter size, location, and the presence of an underlying hypercoagulable state. There are no pharmacologic measures that have been shown conclusively to prevent acute catheter-related upper extremity venous thrombosis. Heparin or antibiotic impregnated catheters are promising technologies. Late thrombosis due to venous stenosis from catheter-related intimal injury can present at a time remote from the venous catheterization. Pacemaker wires are associated with an incidence of occlusive thrombosis of approximately 10% ( Fig. 7-13 ).

Imaging findings of acute venous thrombosis are similar across most imaging modalities, although each has additional specific findings ( Boxes 7-2 and 7-3 ). Patients should be initially evaluated with ultrasound, although the ability of this modality to image the central veins is limited. CT or MR allows diagnosis of thrombus, determination of the extent of obstruction, and identification of contributing pathologic processes in the adjacent soft tissues. Venography is not necessary unless the diagnosis is uncertain or an intervention is contemplated. Chronic venous thrombosis has a different appearance than acute venous thrombosis, but both can and often do coexist ( Box 7-4 ).