Aortic Arch Vessels and Upper Extremity Arteries




INTRODUCTION



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Loss of arm and hand function arguably carries higher morbidity than that of the leg, as there seems to be an unspoken stigma associated with arm or hand loss. Upper extremity function is critical to human interaction within the environment. Hand strength, sensation, and other complex functions protect and provide for human survival and socialization.



Vascular disorders of the upper extremities result in symptoms ranging in severity from nuisance to limb-threatening. Patients with arm-related vascular pathology are encountered by physicians with lesser frequency than lower extremity vascular disease, making diagnosis and treatment unfamiliar to many clinicians who are otherwise skilled in the care of vascular disease. It is paramount that the clinician be able to recognize many of the upper extremity arterial disorders to prevent both overly aggressive treatment, as well as treatment omissions that could lead to tissue loss. This chapter serves to provide an overview of the diagnosis and treatment of frequently encountered vascular disease patterns of the arm.



The arm’s arterial supply consists of the brachiocephalic vessels of the aortic arch, as well as the run-off arterial anatomy of the upper extremities. The disease processes are broken down into three major groups: arterial occlusive/embolic disease, arterial inflammatory disease, and aneurysmal disease of the branch vessels and upper extremities.



In approximately 92% of the population, the aortic anatomy includes, from right to left, the innominate artery, the right common carotid artery, (succeeded across the arch by the origin of the left common carotid artery), and the left subclavian artery. Depending on congenital formation and obliteration of primordial arches allowing for tortuous changes. Over time, the origins of the great vessels can vary in their initiation across the curve of the aortic arch. In general, the more proximal the take-off of the great vessels from the ascending aortic arch, the more difficult catheter-based access becomes when endovascular surgery is performed for subclavian and carotid arterial disease (Figure 28-1).1,2




FIGURE 28-1.


Great vessels arising far right within the aortic arch present challenges in the endovascular treatment of both occlusive and aneurysmal disease of Axillo-subclavian arterial segments.





In 2% to 6% of patients, the left common carotid artery takes its origin from the innominate artery. This arrangement termed bovine arch, can increase the complexity of intervention for innominate arterial disease, as the majority of cerebral inflow is dependent upon the innominate artery. In general, the innominate artery is the largest branch arising from the arch of the aorta. Its origin occurs at the upper border of the second right costal cartilage and because of the angulation of the aortic arch, it is found anterior to the left carotid in the anterior–posterior plane. The innominate artery typically gives off no branches but in 1% of patients a thyroidea IMA takes origin and supplies blood to the lower part of the thyroid body.1



The right common carotid artery arises from the innominate artery behind the right sternoclavicular articulation. The left common carotid artery takes its origin from the highest point in the aortic arch. The left common carotid is typically longer than the right carotid, and takes its origin deeper within the thorax. The left subclavian artery occupies the position posteriorly and slightly left and lateral to this.3,4



Anomalies in aortic arch anatomy can occur during developmental obliteration of the six primordial aortic arches. One observed anomaly includes the origin of the right subclavian artery from the lower aortic arch at the level of the aortic isthmus, crossing posterior to the aerodigestive tract as a result of the partial persistence of a right aortic arch. Chronic compression by aerodigestive structures can result in subclavian arterial aneurysmal degeneration, manifesting as dysphagia or airway-obstructive symptoms.



The number of arch vessels can also be increased from three to four where the right carotid and subclavian arteries arise directly from the aortic arch with the innominate being absent. Based on primordial arch anatomy, this arrangement can be highly variable, and the number of trunks from the arch may be increased to five or six. In such cases, the external and internal carotid arteries can rise separately from the main aortic arch. In rare cases, where six branches are encountered, there are also separate origins of the vertebral arteries directly from the aortic arch. Because of the rare potential variety of arch anatomic configurations, there can be any combination of these anomalies with new challenges presented during the management of aortic arch disease.




GIANT CELL ARTERITIS



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Giant cell arteritis (GCA) is termed temporal arteritis or cranial arteritis. This is a systemic vasculitis affecting segmental portions of the aortic arch and great vessel anatomy.5,6,7 Early signs of this disease process can include headache and partial or complete vision loss as a result of dissection or end-arterial obliteration.8,9 Further catastrophic consequences of GCA can include aortic aneurysmal rupture and cerebral or coronary hypoperfusion syndrome. Additionally, the axillary and brachial arteries can be affected resulting in rapid onset of forearm and hand claudication symptoms. The aortic arch and its branches, particularly the medium diameter branches, are the blood vessels most affected. Rarely, lower abdominal branch vessels including renal, mesenteric, and iliofemoral arteries as well as the coronary arteries can be affected.7



GCA can cause an array of changes to include stenosis, frank occlusion or aneurysmal dilatation. Microscopically the vascular wall is infiltrated with inflammatory cells, particularly monocytes and CD-4 positive T cells, as macrophages are found to penetrate throughout the arterial wall. Multinuclear giant cells are observed and found closely related to the disrupted internal elastic membrane, likely because of the activity of proteolytic enzymes.7,10 Loss of this membrane and medial necrosis can cause formation aneurysms or thickening of the wall acute bouts of arteritis resulting in stenosis or occlusion.



Early signs of GCA include headache, poor appetite, muscle pain, loss of weight and febrile status. Within weeks, severe headaches and jaw claudication can occur.5,6,11 If these symptoms are in fact caused by GCA, 40% of untreated patients may proceed to permanent vision impairment to include blindness, ipsilateral to the affected arteries.



Many patients with GCA demonstrate underlying polymyalgia rheumatica (PMR). PMR can present as pain in the shoulder and hip girdles with weakness and muscle pain during motion.12 Classic symptoms and presentation are rare, therefore, unilateral headaches, particularly those with visual changes, should prompt consideration of GCA and result in the appropriate testing to include measurement of Westergren sedimentation rate (WSR or ESR) and C-reactive proteins (CRP). A WSR greater than 50 mm/h is of concern for GCA but often can exceed 100 mm/h in patients with severe GCA. CRP is noted to be increased in 92% of patients and although this is a nonspecific test, it can be sensitive in detecting GCA. Elevated white blood cell count, platelet count and liver enzymes occur in roughly 30% of patients with GCA. Occasionally, GCA can also be associated with increased anticardiolipin antibodies, compounding the obliterative process because of the associated thrombophilia.5,7,8,10



Treatment of GCA requires confirmation of diagnosis with arterial biopsy done at a low threshold based upon clinical presentation. In patients in their sixth or seventh decade of life, new onset of severe headaches, jaw claudication, or bilateral arm claudication, with or without systemic signs of inflammation, could indicate GCA. Evaluation should include noninvasive arterial waveform testing, arterial biopsy and occasionally arteriography.6 Duplex evaluation of the temporal artery demonstrates the “halo sign.” Waveform plethysmography of the upper extremities may suggest bilateral proximal axillo-subclavian or brachial artery occlusive disease. Brisk onset of such disease is consistent with acute GCA and may present as arm and hand claudication during performance of tasks (Figure 28-2).7




FIGURE 28-2.


(A) GCA can involve segment of the axillary and brachial segments of the upper extremity arterial anatomy. (B) Although the treatment of GCA generally requires the use of steroids to resolve arterial inflammation, occasionally endovascular therapy or surgical bypass can be performed for tissue-threatening occlusive lesions. Here a self-expanding stent is deployed to improve arm arterial runoff in a patient with hand tissue loss.





Unilateral headaches, with or without visual changes and positive ESR and CRP, should prompt vessel biopsy to confirm the diagnosis. Biopsy of the temporal artery should include a minimum 2-cm segment with a longer segment obtained if possible, thereby improving the pathologic sampling of the vessel, as well as the sensitivity and specificity of this clinical test to confirm GCA.10



The acute treatment of GCA includes the administration of corticosteroids. Prednisone can be initiated at a dose of 1 mg/kg per day. However, in those with impending vision loss, prednisone should be administered in a dose of at least 20-mg three times daily. Once the active phase of the disease is controlled, the dose is consolidated to a single daily dose until the vasculitis resolves completely, after which steroid taper is possible. Corticosteroid treatment can be guided by normalization of ESR and CRP. Other medications have included various forms of immunosuppressive drugs, with variable proven clinical efficacy.5*



Surgical bypass for the complications of GCA is typically not performed in the inflammatory setting of acute vasculitis. Where tissue threat is present, principles of surgery include bypass from normal inflow vessels to relatively healthy target vessels while trying to avoid the inclusion of acutely diseased segments in the anastomotic zones of the revascularization. There seems to be little role for endovascular therapy beyond diagnostic imaging of diseased arteries in planning for medical and/or surgical therapy. However, in those patients with severe comorbidities, angioplasty is a reasonable treatment strategy to avoid tissue loss.




RADIATION-INDUCED ARTERITIS



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Radiation-induced arteritis is seen increasingly in patients who have undergone radiation in the treatment of malignancies earlier in life. Ionizing radiation tends to injure rapidly dividing cells and is therefore effective in cancer cells. However, adjacent tissue radiation can result in damage to normal mitotic cells and can result in chronic radiation damage of the vascular tree.13



Endothelial cells are exquisitely radiosensitive. Initially there can be swelling and exfoliation of endothelial cells, which can lead to obstruction of small blood vessels by thrombosis as subintimal collagen is exposed to blood cell constituents. Therefore, the acute damage of small diameter cells results in characteristic “sausage segment” with irregular stenotic occlusion of these vessels. In larger diameter vessels, there can also be damage to the vaso vasora with chronic medial fibrosis producing a narrowed arterial lumen which may require revascularization, depending upon its location within the great vessel anatomy.13




SMALLER ARTERIAL DISEASES OF THE UPPER EXTREMITY



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In the majority of patients with ischemic changes of the hand, there is a relationship to small vessel obstructive disease. The small vessel arterial disease results in symptoms related to vasospasm or obstruction of the small digital arteries of the hand. The vasospastic processes can result in a waxing and waning of ischemic changes, coolness, pain, and numbness. Color changes are often initially observed which may make the patient particularly aware that there is an arterial problem with their digits. Vasospasm can ultimately lead to loss of portions of the digits if the disease goes unchecked.




RAYNAUD’S SYNDROME



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Raynaud’s Syndrome (RS) is the most commonly encountered upper extremity arterial disease process. RS manifests as intermittent digital ischemia in response to environmental cooling of the hand. This can be exacerbated by high cat cholinergic states such as during periods of emotional or physical stress. RS has a classic presentation of tri-colored changes proceeding from white to blue to red, although one or more phases of this color progression may be absent. RS is seen in the cooler and damper climates typical to the United States, Great Britain, and Scandinavia.14,15



RS is subdivided into vasospastic and thrombo-obstructive subgroups. Those with vasospastic RS can be observed as having normal plethysmographic waveforms when symptoms are not present. Vasospasms result in a marked increase in the obstructive characteristics of peaked plethysmographic waveforms (“nipple sign”) in the fingertips, correlating with symptoms. A large portion of the patients (approaching 50%) can proceed to obstructive RS as the vasospasm results in intraluminal small vessel obliteration sufficient to overcome systemic pressure distending forces.15



Treatment of RS initially includes major lifestyle modifications including the liberal use of gloves for thermal protection from environmental cold stress. Patients are encouraged to avoid handling cold objects, and to refrain from submerging their hands in cold water. They are also counseled regarding rapid changes in environmental temperatures such as proceeding into an air-conditioned indoor setting from an otherwise warm day. Underlying life stressors are identified and addressed as is appropriate. Initial pharmacological therapy includes the use of calcium channel blocking medications, and antiplatelet medications.14,15,16 Some physicians recommend medications to alter the rheology of red blood cells to decrease small vessel blood viscosity. Long-acting vasodilators, such as nifedipine (available in a 30-mg slow-release formulation) as well as an antiplatelet medication, can be effective.



Patients refractory to these measures can be treated with either needle directed pharmacological sympathectomy or surgical sympathectomy focusing efforts on the second thoracic segment of the sympathetic ganglia. There are also multiple treatment regimens dependent upon pharmacological sympatholytic agents (primarily alpha adrenoceptor blockade) to affect vasodilatation during severe vasospasm.15,17



Connective tissue diseases can be associated with RS although literature review shows a wide variation in association. Most commonly, these diseases include scleroderma, lupus, polymyositis, and rheumatoid arthritis. Many patients with some connective tissue disease will manifest RS during fulminant courses of their disease process; however, an aggressive search for connective tissue diseases will often be nondiagnostic in those patients presenting with RS alone.14



There are other causes for RS as a secondary process related to primary disease or traumatic insult. Ergot derived drug toxicity and β-adrenoceptor blocking medications can initiate RS as well as acquired arterial occlusive conditions. Arterial thoracic outlet syndrome can also be complicated by secondary RS and the surgical treatment may include T2 sympathectomy to improve vasodilation after thoracic outlet decompression and revascularization.

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Jan 13, 2019 | Posted by in CARDIOLOGY | Comments Off on Aortic Arch Vessels and Upper Extremity Arteries

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