Acute occlusion of the left subclavian artery with artery dissection

Subclavian steal syndrome is cerebral or brain stem ischemia resulting from diversion of blood flow from the basilar artery to the subclavian artery, which is caused by occlusive disease of either the subclavian artery or the innominate artery before they branch off at the vertebral artery. In the patients with subclavian steal syndrome the subclavian artery is fed by retrograde flow from the vertebral artery via the carotids and the circle of Willis. Clinical manifestations of the disease consist of vertigo, syncope, paresthesia, visual disturbance, ophthalmoplegia accompanied by diplopia, cerebellar ataxia, headache, flaccid paralysis (most patients), dysarthria, dysphagy, alienation, tinnitus, dysaudia (few patients), drop attacks (very few patients), ischemia expression in occlusion side upper limb (asthenia, heavy feeling, pain and low skin temperature), low blood pressure in occlusion side upper extremity with systolic pressure difference more than 3.0 kPa (20 mmHg), radial artery pulsation weakening and vanishing, and vessel murmur in the artery passing area. Activities or weight loading will aggravate these symptoms obviously. CLINICAL DATA Patients From October 2004 to May 2004, 7 patients with acute occlusion of the left subclavian artery were treated in our hospital (5 men and 2 women, aged 42 to 73 years, mean 62.7 years). Their manifestations included sudden aggravation fatigue, heavy feeling, ache, low skin temperature, low blood pressure (the difference between the two arms was more than 20 mmHg), weakness or absence of left radial pulse in the left extremity, which were aggravated after activities complicated with vertigo, visual disturbance, ataxia, diplopia and syncope causing by ischemia of the brain stem, occipital lobe, or cerebella. Magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) showed occlusion at the origin of left subclavian artery (Figs. 1 and 2A). A reverse flow from the right vertebral artery to the subclavian occlusion was also found by DSA (Fig. 2B).Fig. 1.: MRA of the subclavian artery showing the occlusion at origin of the left subclavian artery with “mouse tail's sign”. Arterial blood flow reversely from the left artery.Fig. 2.: DSA of the left subclavian artery in a patient. A: The origin of the left subclavian artery is occluded with a “mouse tail's sign”. B: A reversal flow from the left vertebral artery to the left subclavian artery.Intervention therapy Before operation, the ACT value of the patients ranged from 200 to 300 s. Local anesthesia was used on all the patients, during the operation, their blood pressure, SO2, electrocardiogram and ACT value were monitored. After heparinization, catheter was intervened through the femoral artery and humeral artery. First, the catheter was put into the aorta to make angiography. Then, a 4F catheter was inserted into the proximal segment of the left subclavian artery through a 6F catheter sheath, which had been pierced into the humeral artery at the elbow. At the extremity of the left subclavian artery, “mouse tail's sign” was found, demonstrating the occlusion of origin part of the artery. After being placed at the occlusion site, the tip of micro-guidewire was found purling or curling, suggesting that it lay in the dissection. And the dissection can be further proved with developer (Fig. 3).Fig. 3.: DSA showing artery dissection in a patient. A: Subendometrium hemorrhage in the aortic arch. B: Artery dissection at the origin of the left subclavian artery. C: A stent is placed at the lesion via the left brachial artery. A normal flow is shown in the left subclavian artery without steal flow.After the developer was pumped out, the micro-guidewire was put into the aortic arch through the subclavian artery. According to the size of lesion, a bracket was put into the occlusive part. If the bracket did not expand fully, an adaptive balloon (sacculus) was used to make dilation (8 atm, 1 —2 times) to 95% of normal diameter under the help of a micro-guidewire (0.035/260 mm). Then a stent was placed under the guidance of angiography via the femoral artery. And the blood flow restored in the left subclavian artery, left vertebral artery and left radial artery, the reversal flow disappeared. After the operation, anticoagulation was prescribed and Doppler examination was performed to monitor the blood flow and the stent. Outcomes Seven patients with acute occlusion of the subclavian artery were successfully operated. Their occlusive left subclavian arteries were expanded. The opening of the dissection was obstructed. The left upper limb ischemia in one of the 7 cases disappeared 3 days after treatment. All the patients were followed up for 2 to 6 months through color Doppler ultrasonic examination. During the followup, the blood flow in the left subclavian artery and left vertebral artery were normal. The stents expanded completely and did not move to other places. DISCUSSION Subclavian steal syndrome is an uncommon disease caused by atherosclerosis, unspecific inflammation, Takayasu's disease, arteritis, or artery compression. The disease can happen at any age with varied clinical manifestations. About 50 percent of the patients have no symptoms because of their intact Circle of Willis. Some patients have vertigo, visual disturbance, incoordination, diplopia and syncope resulting from ischemia in the brain stem, occipital lobe or cerebella. Those who have occlusion in the proximal segment of subclavian artery must have brain ischemia, because of the absence of collateral circulation. In this study, we reviewed acute occlusion of the left subclavian artery caused by atherosclerotic plaque. The so-called artery dissection is cased by arterial blood flowing into the tunica intima or tunica media because of disruption of the intima and elastic fibers, resulting in laceration and detachment of the intima or tunica media. There are 3 kinds of lesion involved in left subclavian steal syndrome: aorta dissection type III (Debackey typing), subintimal hemorrhage at the origin of left subclavian artery, atypical artery dissection (The ulcer or disruption of the arterial intima cause the blood flow into the media, develop a nonreentry site). The rupture of the nourishing vessels of artery wall results in hematoma formation leading to an artery dissection. In this series, aorta dissection (Dcbackey III ) occurred in one case. The rupture site was around the origin of left subclavian artery. The other 6 cases had atypical artery dissection at the origin of left subclavian artery. All of the 7 patients had a long history of hypertension. Before the onset of the disease, 6 of them experienced emotion agitation and abrupt increase in blood pressure. Thus we think that emotion agitation and overtiredness may be the provocation of the disease. There are many ways to treat subclavian steal syndrome including traditional surgery, percutaneous transluminal angioplasty, and stent implantation. Traditional surgery is effective, but is difficult to perform with a high mortality. The cure rate of percutaneous transluminal angioplasty is 97% with a complication rate of 2%. The complications include upper extremity ischemia, pseudoaneurysm, and hematoma around the puncture point.1–8 In those who have serious constriction or obstruction of the subclavian artery, however, the cure rate is about 83%.9 Recently developed stent implantation and transluminal angioplasty are better for the disease, because of uncomplicated operation and no remained stenosis. In addition, stents can help to block the ruptured tunica intima, stop the leakage of blood, and prevent hemorrhage from the plaque and nourishing vessels of the intima. Therefore, stent implantation and transluminal angioplasty are indicated for patients with acute occlusion of the left subclavian artery, but not for those with tumor, aneurysm compression, extensive vessel lesion caused by unspecific arteritis, and Takayasu's disease. Moreover, coagulation dysfunction and severe systemic diseases are contradictions to the operations. From our experience, transfemoral catheterization is difficult to carry out because of unstable opening site of the left subclavian artery, vascular deformation, and abnormal blood flow caused by arteriosclerosis; and that during transbrachial operation, it is hard to judge the positions of the guidewire and catheter. When the guidewire and catheter are inserted into the dissection, injection of contrast medium will enlarge the dissection or even rupture the vessel. Interventional therapy via both the femoral and brachial arteries is better than the two mentioned above. In this series, we made the diagnosis by inserting guidewire through the femoral artery, then introduced catheters via the brachial artery to find the rupture of the intima and sucked the blood out of the dissection. After that, we put the catheter into the aortic arch through the occlusive site. Once the stent was placed, the other procedures were done through the femoral artery so that reduce complications. By monitoring the trans-femoral artery, the catheterization through the brachial artery was direct, safe and unblinded. It should be noted that, however, long-term interventional operation via the left brachial artery may leads to left upper limb ischemia. Therefore, interventional therapy via both the femoral and brachial arteries suit for patients with subclavian constriction or occlusion, especially for those with complicated diseases. In one case of this group, we could not find out the opening of left subclavian artery via the femoral artery because of complete occlusion at the origin of left subclavian artery, deformation of the aortic arch caused by dissection, and the blood stream. So we finished the operation by using both the femoral and brachial arteries. In another case, the guidewire always entered into the dissection but not the aortic arch via the transbrachial artery because of an untypical dissection, while transfemoral artery angiography could confirm that the place of stent was suitable. In the other cases, we got good outcomes by using trans-femoral and brachial arteries. In this group, there was one patient had left upper limb ischemia after the surgery resulting from long duration of the operation, which may be avoided by good technique and appropriate guidewires.