In contemporary practice, catheter-based interventions have become an increasingly important therapeutic modality for the treatment of nearly all areas of the peripheral arterial and venous system, including the head, neck, and great vessels, as well as the upper and lower extremities. A thorough understanding of the peripheral arterial and venous anatomy is the foundation for any successful peripheral vascular interventional procedure. This chapter describes the arterial and venous anatomy above and below the diaphragm, with emphasis on the pertinent anatomic variants and radiographic examinations in the catheterization laboratory.

The vascular anatomy of the aortic arch and upper extremities begins at the level of the sinus of Valsalva. From the sinotubular ridge, the ascending aorta travels anteriorly and superiorly, passing over the main pulmonary artery and left mainstem bronchus. At this level, the mean diameter of the ascending thoracic aorta in the normal adult human is 3.5 cm.

The brachiocephalic or right innominate artery is the first major branch off the aortic arch. The next major vessel that arises from the aortic arch is the left carotid artery. The left subclavian artery is the last great artery that arises directly off the aortic arch. After the left subclavian artery arises, the aortic arch ends. This anatomic region, called the isthmus, is found between the last great vessel and the attachment of the ductus arteriosus, after which the descending aorta begins and continues down to the level of the iliac bifurcation.

In 30% of patients, the normal relationship described above is not seen. The most common variants are a shared ostium of the brachiocephalic artery and the left carotid artery (15%), or the so called “bovine arch,” where the left carotid artery arises from the proximal aspect of the brachiocephalic trunk (10%). Other common variants include the right subclavian arising from the arch distal to the left subclavian artery and the left vertebral artery arising directly from the aortic arch (5%) between the left carotid and left subclavian arteries.^1,2 In healthy individuals, the great vessels arise from the horizontal portion of the aortic arch, but with increasing age, the vessels tend to shift counterclockwise toward the ascending aorta.

The right innominate or brachiocephalic artery gives rise to the right subclavian artery and right common carotid artery. After the bifurcation of the subclavian and carotid arteries on the right, the next vessels that arise off the right subclavian include the right vertebral artery and the right internal mammary artery. The right subclavian artery then gives rise to the thyrocervical trunk and the costocervical trunk. At this location, the subclavian artery becomes the axillary artery after it crosses the lateral margin of the first rib. On the left, the subclavian artery gives rise to the left vertebral artery and the left internal mammary artery. Anatomically, its course is similar to the right subclavian artery, giving rise to similar branches.

The axillary artery on both the left and the right gives rise to several small branches around the shoulder, including the superior thoracic, thoracoacromial, lateral thoracic, subscapular, and circumflex humeral artery. It then becomes the brachial artery at the lateral margin of the teres major muscle. The brachial artery divides into the radial and ulnar arteries in the antecubital fossa. In relationship to surface markers, the brachial artery bifurcates a few centimeters below the elbow joint. The ulnar artery then undergoes anastomosis with the median artery and forms the superficial palmar arch in the hand. The radial artery forms the deep palmar arch. The remaining axial artery at the level of the radial–ulnar bifurcation is known as the interosseous artery. Because radial artery access has become increasingly popular for cardiac procedures, an understanding of radial artery anatomic variations is important to performing successful radial catheterization procedures. Radial artery variations are present in 9.1% of the population, with abnormal origin of the radial artery occurring in 5.2%, radioulnar loop in 1.5%, and significant tortuosity noted in 5.6%.³

Arteriography of the aortic arch is carried out for diagnostic purposes and to plan interventions. Anteroposterior (AP) and 45° to 60° left anterior oblique (LAO) projections are initially used to image the arch and great vessels. Imaging the right brachiocephalic territory is best accomplished in a right anterior oblique (RAO) projection with caudal angulation. For selective shots of the left subclavian artery, an AP projection or steep LAO views are useful (Table 5-1).

When performing diagnostic angiography of the aortic arch, it is important to determine the specific type of aortic arch (Fig. 5-1), identify any anatomic variation, and identify the presence of atherosclerotic disease, as these factors can determine both catheter selection as well as interventional technique. The three types of aortic arch are determined by the takeoff of the great vessels relative to the horizontal portion of the greater curvature and assist the clinician in determining the level of complexity and choice of catheters for selective engagement. For example, selective carotid angiography of a type I and most type II arches can be accomplished using a JR4 diagnostic catheter, whereas a type III arch would favor a Vitek or Simmons catheter.

Because arteriovenous fistulas are prone to degeneration and may be suitable for percutaneous intervention, knowledge of the venous anatomy is useful. Furthermore, placement of devices, such as pacemakers and automatic implantable cardioverter-defibrillators, requires use and knowledge of upper extremity venous anatomy. The venous system of the upper extremity is predominantly superficial. The dorsal venous network of the hand empties into the basilic vein, the cephalic vein, and the antecubital veins. The cephalic vein originates dorsally and laterally, crossing the elbow joint and entering the superior aspect of the axillary vein just above the clavicle. The basilic vein, which originates on the ulnar side of the arm, continues medially to the brachial artery. It joins the brachial vein to become the axillary vein at the border of the teres major muscle. The medial cubital veins are the veins that connect the basilic and cephalic veins in the antecubital fossa.

The deep veins in the upper arms and chest follow their respective arteries. The axillary and cephalic veins become the subclavian veins, which are continuations of the axillary veins. As the subclavian veins cross the sternum, they join with the internal jugular veins to form the brachiocephalic veins. The left brachiocephalic vein is longer than the right. The right and left brachiocephalic veins join behind the first anterior rib to form the superior vena cava. The azygous vein forms at the level of the second lumbar vertebra. It travels in the anterior aspect of the posterior mediastinum to the right of the midline and arches anteriorly to join the superior vena cava just above the entry into the pericardium.

Persistent left superior vena cava is an important anatomic variant that occurs in 0.5% to 2% of the general population. In this condition, the left brachiocephalic vein does not develop fully, and the left upper limb and head and neck drain into the right atrium via the coronary sinus. The variation, in isolation, is considered benign, but it is frequently associated with congenital heart defects.⁴

The carotid and vertebral arteries are becoming increasingly important to the interventional cardiologist as endovascular therapy has become a more viable option for atherosclerotic disease of these vessels. The right common carotid artery arises in a reliable fashion from the right innominate artery and travels superiorly. It then bifurcates into the right internal and external carotid arteries. Anatomically, the left common carotid artery arises directly from the aortic arch and travels cephalad to bifurcate into the left internal and external carotids. As detailed earlier, however, the left common carotid has a more variable course in 30% of cases and may arise as a shared ostium or a direct branch of the right innominate. The common carotid arteries are paired vessels, located anteriorly within the neck. The bifurcation of the common carotid arteries into the internal and external arteries on both sides is generally at the level of cervical vertebra C3 to C4.⁵ In some patients, the bifurcation is significantly higher and arises deep in the mandible, which would require dislocation for carotid endarterectomy. The proximal portion of the carotid bifurcation houses the carotid sinus, which regulates baroreceptor reflexes via the glossopharyngeal nerve and can cause bradycardia and hypotension during carotid intervention.

Both internal carotid arteries supply the anterior circulation of the brain as well as a portion of the skull base. The first segment of the internal carotid artery is the cervical segment, which has no branches. This is the only segment of the internal carotid artery that is extracranial and is the target for conventional endovascular intervention. The remaining three segments of the internal carotid artery are named in relation to their location in the skull: the petrous and cavernous portions, which lie within the petrous bone and cavernous sinus, respectively; and the supraclinoid segment, which runs above the level of the anterior clinoid process. The internal carotid artery runs posterolateral to the external carotid artery and then courses medially to enter the skull base through the carotid canal (Fig. 5-2). The area of the brain supplied by the anterior and middle cerebral arteries is termed the carotid territory.

The external carotid artery is a smaller artery in relation to the internal carotid artery. The distinguishing feature of the external carotid artery is its branches (Fig. 5-3): the superior thyroid, ascending pharyngeal, lingual, facial, occipital, and posterior auricular arteries. A general understanding of the branches originating from the external carotid artery is important as these branches are often wired during intervention. The external carotid artery then terminally bifurcates into the internal maxillary and superficial temporal arteries. Some patients develop temporary jaw claudication after carotid stenting if the ostium of the external carotid is compromised, but this is usually temporary and infrequently requires any intervention.

Arteriography of the carotid arteries is carried out primarily in two views: a lateral projection and an AP view with cranial angulation. The lateral view serves to separate the internal (posterior, no branches) from the external (anterior, with branches) carotids and to image the bifurcation and common carotid. Often, oblique views can also accomplish this. The AP view best characterizes the common carotid and the distal internal carotid arteries. As the internal carotid enters the cranium, it traverses the cavernous sinus and forms a siphon-like S curve. It is critical to maintain wire position below the level of the siphon because an intracranial perforation or dissection could occur if the wire or a distal protection device is allowed to enter the intracranial carotid. It is also critical to image the intracranial carotid both before and after carotid stenting to define the key branches where complications can arise. Structures of key importance include the ophthalmic, anterior cerebral, and middle cerebral arteries, which should all be closely interrogated after the procedure for occlusion or compromise (see Fig. 5-2).

The vertebral arteries arise as the primary branches of the subclavian arteries, supplying the posterior circulation of the brain, spinal cord, and muscles of the neck. Vertebral arteries enter the foramina of the C6 vertebra and then run within the bony canals, exiting at the C2 foramina. These arteries then turn laterally to course around the C1 vertebra before returning medially to ascend through the foramen magnum to join and form the basilar artery. The most common views of the vertebral arteries are anteroposterior. The ostia of the vertebral arteries are best captured by contralateral oblique projection.