Conventional Surgical and Endovascular Treatment of Innominate Artery Atherosclerosis



Conventional Surgical and Endovascular Treatment of Innominate Artery Atherosclerosis



Mark K. Eskandari


The arterial blood supply to the upper extremities and brain is based on the supra-aortic trunk vessels, which include the innominate, left common carotid, and left subclavian arteries. The innominate artery is unique in that it is solely responsible for the circulation to the right arm and entire right hemisphere of the brain. Although a variety of pathologic disease processes are known to affect the innominate artery, atherosclerotic occlusive disease is the most common. Typically, atherosclerotic involvement represents spillover from a diseased aortic arch and is generally isolated to the ostium of the vessel.




Diagnosis


The diagnosis of an innominate artery stenosis or occlusion is best achieved using noninvasive radiographic imaging. Duplex ultrasound can provide indirect evidence of an innominate arterial lesion by detecting reduced flow velocities in the right common carotid and subclavian arteries, but direct assessment is best achieved with either contrast-enhanced computed tomography angiography (CTA) or magnetic resonance angiography (MRA). Duplex ultrasound is hampered by the inability to directly image the innominate artery in the chest, whereas CTA and MRA provide cross-sectional, sagittal, coronal, and three-dimensional views of the innominate artery. Moreover, CTA and MRA provide additional detail of the plaque morphology and characteristics of the atherosclerotic lesion. Contraindications to CTA are the risk of radiation exposure and sequelae of intravenous iodinated contrast administration. MRA is generally avoided in cases of claustrophobia and preexisting ferromagnetic elements such as a pacemaker. If noninvasive imaging is not feasible, then conventional angiography can be used to accurately assess the innominate artery.



Treatment


Medical therapy remains a cornerstone for atherosclerotic innominate artery disease. In certain instances, additional surgical or endovascular treatment is advocated. Although this particular disease has not been as well studied as extracranial carotid artery disease with randomized studies, the guidelines for proceeding with surgical or endovascular treatment are similar: symptomatic disease with at least 50% stenosis or asymptomatic disease with at least 80% stenosis.



Surgical Techniques


Traditional open surgical treatment of atherosclerotic innominate artery disease is typically divided into transthoracic bypass, transthoracic endarterectomy, or extra-anatomic cervical bypass. The transthoracic bypass is considered the gold standard, but all three are effective and durable therapies. An extra-anatomic bypass is generally reserved for patients deemed unable to undergo a median sternotomy for definitive treatment owing to a prior sternotomy, severe cardiopulmonary disease, or extensive ascending or aortic arch disease. The primary risks associated with these approaches are cranial nerve injuries, stroke, and myocardial infarction.



Transthoracic Bypass


Preoperative cardiopulmonary assessment is necessary before a transthoracic aortic–innominate artery bypass. Generally, noninvasive cardiac imaging is sufficient. However, if there exists any concern about underlying coronary artery or significant valvular disease that could require surgical treatment, it is best to determine this before proceeding with the median sternotomy. Because the bypass inflow is typically based off the ascending aorta, it is important to evaluate the size and quality of the aorta in this location. Heavy calcification or extensive intraluminal thrombus is a contraindication caused by the increased risks of stroke and localized injury to the aorta during clamping under these conditions.


A standard median sternotomy is used to access the ascending aorta and innominate artery. The thymus is divided and the innominate vein is preserved. The pericardial sac is opened and the ascending aorta is exposed. Next, the innominate artery is dissected above the innominate vein up to the bifurcation into the right common and subclavian arteries, taking care not to injure the recurrent laryngeal nerve. After the intravenous administration of weight-based systemic heparin sulfate, the right lateral wall of the ascending aorta is clamped with a side-biting clamp (i.e., Lomel-Strong clamp). Pharmacologic lowering of the systemic blood pressure by the anesthetic team during this time is helpful.


The proximal anastomosis is performed in a beveled fashion to the ascending aorta using a 10- or 12-mm prosthetic graft (i.e., polyester or polytetrafluoroethylene) and 3–0 or 4–0 polypropylene sutures. The graft is then clamped and the side-biting clamp is removed. Next, the innominate artery is controlled with vascular clamps and transected above the offending lesion, and the proximal portion of the artery is oversewn. The graft is positioned anterior to the innominate vein and sewn end-to-end to the distal innominate artery with 4–0 or 5–0 polypropylene sutures (Figure 1).


Jul 15, 2018 | Posted by in CARDIOLOGY | Comments Off on Conventional Surgical and Endovascular Treatment of Innominate Artery Atherosclerosis
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