CHAPTER 9 Upper extremity arteries

Arteriography (video 9-1)

The brachiocephalic, left carotid, and left subclavian arteries are catheterized from a common femoral artery approach with a 4- or 5-French (Fr) vertebral or headhunter catheter. The catheter is advanced over a guidewire into the ascending thoracic aorta and then simultaneously torqued and withdrawn at the groin until the tip engages the artery of interest (Fig. 9-1). In older patients with ectasia of the aorta and arch vessels, a reverse-curve catheter may be useful (Fig. 9-2). When atherosclerotic disease is present, gentle catheter manipulations are essential to avoid dislodging aortic plaque fragments into the brain or periphery. Even minute air bubbles or clots released during catheterization of arch vessels and their branches may cause a stroke (through the carotid or vertebral arteries) or paraplegia (e.g., through spinal branches of the costocervical artery.) Therefore meticulous double flushing with uncontaminated saline is done every 60 to 90 seconds if blood can be aspirated from the catheter.

Figure 9-1 Steps in catheterization of the arch vessels with a headhunter catheter. The catheter can then be advanced into the right subclavian artery over a guidewire. Further withdrawal of the catheter (third panel) will cause it to jump into the left common carotid and then into the left subclavian artery.

(Adapted from Kadir S. Diagnostic angiography. Philadelphia: WB Saunders, 1986:177.)

Figure 9-2 Steps in catheterization of a tortuous brachiocephalic artery with a Simmons catheter.

(Adapted from Kadir S. Diagnostic angiography. Philadelphia: WB Saunders; 1986: p.178.)

During arteriography of the upper extremity, a high origin of the radial artery from the brachial or axillary trunk should be sought (see later discussion). In this situation, the catheter tip is positioned proximal to its take-off. Arteriography of the hand is usually performed with a catheter in the midbrachial artery. The arteries of the hand and forearm are especially prone to vasospasm, which may be prevented or relieved by intraarterial injection of a vasodilator (e.g., 100 to 200 μg of nitroglycerin).

In some instances, arteriography of the forearm and hand is accomplished by direct antegrade brachial artery puncture (see Chapter 3). For example, this approach is useful to evaluate the anastomosis of a dialysis fistula that is not easily accessible directly from the access itself.

Anatomy (online cases 3 and 17)

Development

In early gestation, the upper limbs are nourished by the axial artery. This vessel evolves into the axillary, brachial, interosseous, and median arteries that feed the hand in the fetus.¹ The ulnar artery is an outgrowth of the brachial artery at the elbow. The radial artery arises from a superficial branch of the proximal brachial artery, but its origin migrates toward the elbow as the fetus grows. In most cases, the distal interosseous and median arteries regress before birth.

Normal anatomy

The subclavian arteries originate from the brachiocephalic (innominate) artery on the right and directly from the aortic arch on the left ² (Fig. 9-3). The artery runs posterior to the subclavian vein and the anterior scalene muscle. It arches over the pulmonary apex within the costoclavicular space surrounded by nerves of the brachial plexus. The subclavian artery has several major branches (Fig. 9-4):

• The vertebral artery exits the superior aspect of the vessel and travels through the bony canal of the cervical transverse processes into the skull.

• The internal thoracic (mammary) artery exits the undersurface of the subclavian artery opposite the vertebral artery and runs behind the costosternal junctions (Fig. 9-5). The vessel divides into musculophrenic and superior epigastric branches. The internal thoracic artery and its musculophrenic branch give rise to the anterior intercostal arteries. The musculophrenic and superior epigastric branches have anastomoses with the inferior phrenic and inferior epigastric arteries, respectively, in the abdomen.

• The thyrocervical trunk takes off beyond the vertebral artery origin and immediately divides into the inferior thyroid, suprascapular, and superficial cervical arteries.

• The costocervical trunk gives rise to the superior intercostal artery (source of the first, second, and, occasionally, third posterior intercostal arteries) and the deep cervical artery. Small branches may supply the anterior spinal artery.

• The dorsal scapular artery is the final branch of the subclavian artery.

Figure 9-3 Thoracic aorta and arch vessels in right posterior oblique projection.

Figure 9-4 Arteriogram of the right subclavian and axillary arteries.

Figure 9-5 Right internal thoracic (mammary) arteriography. The vessel continues as the superficial epigastric artery as it enters the abdomen (arrow).

At the outer edge of the first rib, the subclavian artery becomes the axillary artery (see Fig. 9-4). The vessel runs deep to the pectoralis major and minor muscles and lateral to the axillary vein. Its major branches include the superior thoracic, thoracoacromial, lateral thoracic, subscapular, and anterior and posterior humeral circumflex arteries. These branches supply muscles of the shoulder girdle, humerus, scapula, and chest wall.

At the lateral edge of the teres major muscle (approximately the lateral scapular border), the axillary artery becomes the brachial artery. In the mid-upper arm, the artery lies in a fascial sheath along with the basilic vein, paired brachial veins, and the median and ulnar nerves. Its major branches include the deep brachial and the superior and inferior ulnar collateral arteries (Fig. 9-6). At about the level of the radial head, the brachial artery divides into the radial and ulnar arteries (Fig. 9-7). The radial artery obviously descends on the radial side of the forearm. The ulnar artery, which is usually the larger of the two, gives off the common interosseous artery and then descends on the ulnar side of the forearm. The interosseous artery divides into anterior and posterior branches separated by the interosseous membrane. In less than 10% of individuals, the anterior interosseous or median artery persists and contributes to the palmar arch.³

Figure 9-6 Arterial anatomy and collateral circulation of the upper arm and elbow.

Figure 9-7 Right forearm arteriogram. The brachial artery bifurcates into radial (R) and ulnar (U) arteries. The ulnar artery gives off anterior and posterior interosseous arteries (I). Also note an unusually prominent median artery (M).

The arterial anatomy of the hand is extremely variable, and deviations from the classic pattern described here are common.³^,⁴ The ulnar artery supplies the superficial palmar arch, and the radial artery supplies the deep palmar arch (Figs. 9-8 and 9-9). The arches often are in continuity with the opposing forearm artery through small branches at the wrist. The superficial arch is dominant and typically forms distal to the deep arch. The princeps pollicis and radialis indicis arteries arise from the radial artery and supply the thumb and index finger, respectively. The superficial palmar arch gives off three or four common palmar digital arteries, and the deep arch gives off the palmar metacarpal arteries. At the bases of the proximal phalanges, adjacent metacarpal vessels from each arch merge and then immediately divide into proper digital arteries, which supply apposing surfaces of the fingers. A so-called incomplete superficial arch, defined by lack of continuity of the radial artery with the superficial arch and lack of supply of the thumb and medial index finger by the ulnar artery, is found in about 14% to 20% of the population in autopsy studies.³^,⁴

Figure 9-8 Arterial anatomy of the hand.

(Adapted from Loring LA, Hallisey MJ. Arteriography and interventional therapy for diseases of the hand. Radiographics 1995;15:1299.)

Figure 9-9 Normal hand arteriogram. Note superficial (S) and deep (D) palmar arches.

Variant anatomy

Anomalies of the subclavian artery origin are discussed in Chapter 6. In about one third of the population, the superficial cervical and dorsal scapular arteries have a common origin from the thyrocervical artery (i.e., transverse cervical artery). Variations in muscular branches of the axillary or brachial artery are common but do not have much clinical relevance.⁵^,⁶

“High” origin of the radial artery from the axillary or upper brachial artery is an important variant (Fig. 9-10). This anomaly results when the radial artery origin fails to migrate distally toward the elbow during gestation. It was found in 14% of cases in one autopsy series.⁶ A high origin of the ulnar artery is far less common. Duplications of the brachial artery and hypoplasia or aplasia of the radial and ulnar arteries are rare variants.

Figure 9-10 High origin of the radial artery (arrow) from the axillary artery. Note diffuse arterial spasm in the setting of acute fracture of the right humerus.

The persistent median artery reflects lack of regression of the embryonic median branch of the common interosseous artery (Fig. 9-11). It was identified in 3.4% of cases in one large operative series.⁷ This vessel may supply a palmar arch.

Figure 9-11 Prominent persistent median artery (arrow).

Collateral circulation

With proximal subclavian artery obstruction, blood may flow from the contralateral vertebrobasilar system into the ipsilateral mid-subclavian artery (see later discussion). When the obstruction is more distal, major collateral pathways are present across the thyroidal arterial system, between the internal thoracic and lateral thoracic arteries, and between the thyrocervical trunk and circumflex humeral arteries. With axillary artery obstruction, a rich network of muscular branches around the shoulder girdle provides collateral blood supply into the brachial artery.

In proximal brachial artery obstruction, the subscapular and posterior humeral circumflex arteries provide flow through muscular branches into the distal brachial or forearm arteries ² (see Fig. 9-6). In cases of midbrachial artery occlusion, the deep brachial artery and superior ulnar collateral arteries supply the radial recurrent and ulnar recurrent arteries, respectively, above the elbow. The radial and ulnar recurrent arteries are the chief pathways across the elbow in patients with distal brachial artery occlusions.

When the radial or ulnar artery is obstructed, the opposing forearm artery, along with the anterior interosseous or median artery (if persistent into the wrist), supplies the hand. Collateral circulation with occlusion of the distal forearm or hand vessels depends on the individual anatomy and continuity of the palmar arches.

Major disorders

Acute upper extremity ischemia (online case 64)

Etiology

Acute ischemia is far less common in the arm than in the leg. This disparity is partially explained by the extensive collateral network around the scapula and shoulder and by the smaller muscle mass and metabolic needs of the arm. Emboli account for about 50% of cases of acute arterial occlusion, and most come from the heart ⁸^–¹⁰ (Box 9-1). About one fourth of cases result from iatrogenic or accidental trauma leading to arterial thrombosis. In the remainder, acute thrombosis is caused by superimposed atherosclerotic plaque, local extrinsic disease (e.g., thoracic outlet syndrome), aneurysm, or arteritis.

Clinical features

Most embolic occlusions occur in older patients with a history of cardiac dysrhythmias, myocardial infarction, or valvular heart disease. Sudden and complete upper extremity arterial obstruction causes abrupt onset of arm pain, coolness, cyanosis, pallor, diminished or absent pulses, and, occasionally, sensorimotor deficits. However, some patients are only mildly symptomatic if the underlying disease is chronic (as with thrombosis at a site of preexisting atherosclerotic stenosis) and collateral circulation is robust. The presence of arm swelling should raise the suspicion of severe venous thrombosis (see Chapter 17).

Imaging

Duplex sonography, computed tomography (CT) angiography, and magnetic resonance (MR) angiography are sometimes used in the initial evaluation of patients who do not go directly for operation ¹¹^–¹³ (Fig. 9-12). Catheter angiography is usually reserved for cases in which endovascular treatment is planned. It is customary to investigate the entire circulation from the aortic arch to the digital arteries of the hand to identify potential sources of emboli and to search for occult distal disease. An acute embolus produces a discrete filling defect with reconstitution of the distal vessels. However, it also may appear as a sharp cutoff that mimics a thrombotic occlusion (Fig. 9-13). After the embolic event occurs, clot propagates proximally and distally to the next large collateral branches. Post-traumatic thrombosis results in an abrupt occlusion at or near the site of injury (Fig. 9-14).

Figure 9-12 Brachial artery embolus. A, On contrast computed tomography angiography, the patent right brachial artery (arrow) becomes filled with thrombus on more distal image (B,arrow). C, On a reformatted image, the short segment brachial artery occlusion (arrows) is depicted.

Figure 9-13 Embolus to the left brachial artery in a patient with thoracic outlet syndrome. A through C, Contrast-enhanced computed tomography images show left subclavian artery (arrow) abutting callus from an old clavicular fracture with post-stenotic dilation of the artery (arrow). Unlike the right brachial artery (arrowhead), the mid left brachial artery is thrombosed (curved arrow). D, Left subclavian arteriogram shows mural thrombus within the dilated segment of the left subclavian artery (large arrow) and complete occlusion of the proximal left brachial artery (small arrow).E, Weak collateral flow is found in the upper arm. F, Following overnight thrombolysis with t-PA at 1 mg/hr, the proximal occlusion is completely gone. Flow is noted to the distal left brachial artery (G), with collateral filling of forearm arteries (H). I, With the left arm in extreme abduction, narrowing of the subclavian artery is noted (arrow).

Figure 9-14 Thrombosis of the left brachial artery after catheterization.

Treatment

Blood flow to the arm must be restored promptly (within about 4 to 6 hours after acute occlusion in the absence of preexisting collateral circulation) to avoid ischemic peripheral neuropathy, irreversible muscle necrosis, and (ultimately) amputation.¹⁴

Surgical therapy

Anticoagulation and embolectomy with a Fogarty catheter are standard treatment for embolic occlusions.⁸^–¹⁰^,¹⁵ If the symptoms are mild and the clot burden is small, the patient can sometimes be managed with anticoagulation alone. Thrombotic occlusions are repaired by direct thrombectomy, patch revision, or bypass grafting.

Endovascular therapy

Thrombolysis is an attractive alternative to surgery for some acute upper extremity arterial occlusions.¹⁶^,¹⁷ Acute embolic occlusions are very responsive to enzymatic thrombolysis, which achieves complete or near-complete clot lysis and limb salvage in many cases¹⁸^,¹⁹ (see Fig. 9-13). Techniques for extremity arterial thrombolysis are considered in Chapter 3. Liberal use of intraarterial vasodilators is recommended to combat vasospasm, which occurs frequently with upper extremity artery manipulations. Because the collateral circulation in the arm and hand is so extensive, even partial lysis of an occlusion may avoid amputation or at least limit its extent. Occlusions less than 48 hours old respond better to thrombolysis than do older ones. An important advantage of lytic infusion over surgery is the ability to lyse clots in small vessels of the forearm and hand. Stroke from embolization of pericatheter clot has been reported with prolonged infusions, but it is a rare complication.

Chronic upper extremity ischemia (online case 29)

Etiology

A variety of diseases may cause subacute or chronic upper extremity ischemia ²⁰^,²¹ (Box 9-2). Atherosclerosis usually affects the proximal segments of the subclavian artery and less often the brachiocephalic artery. Oddly, symptomatic disease is far more common in the left than the right subclavian artery. The various sources of thromboemboli were considered in the previous section.