Experience of interventional treatment of subclavian artery stenosis and precautions
1.Stenosis calculation: SA stenosis degree (%) = (1 a diameter of the narrowest part of the vessel / diameter of adjacent normal vessels) × 100%; if there is no blood flow through, it is judged as occlusion.
2.Percutaneous translu-minal angioplasty (PTA) is performed according to the degree of stenosis. If the angiogram shows ≥70% stenosis, pre-PTA will be performed to facilitate endoprosthesis placement; if the stenosis is <70%, post-PTA will be performed depending on the post-stent placement angiogram results. After the guidewire crosses the stenotic/occluded segment, PTA can be performed.
3. The size of the dilating balloon diameter is selected with reference to the size of the adjacent normal vessel diameter in the lesioned segment, and the length of the dilating balloon should exceed the length of the lesion. Hand-push the diluted contrast syringe for PTA treatment;
4, before dilatation are injected into the vessel through the catheter nimodipine to prevent the occurrence of vasospasm, at the same time, intraoperative heparin sodium 4000 ~ 6 000 u anticoagulation.
5. The diameter of the endoprosthesis was selected according to the size of the normal vessel diameter adjacent to the diseased vessel. Generally, the diameter of the selected endoprosthesis should exceed the diameter of the vessel by about 10%, and its length should be 1.0 cm across each end of the lesioned segment.
6.After the postoperative anticoagulation treatment, the anticoagulation treatment should be continued. 6,000-12,000 u/d of sodium heparin should be used intravenously for 3-5 days, and aspirin should be used orally for 40 mg/d twice a day for 3 months.
7. In one case with SA thrombosis before surgery, 1 week after the endoprosthesis was placed, the ischemic symptoms of the upper limb on the side of the lesion recurred, and the formation of thrombus in the stent was confirmed by imaging, and normal blood flow was restored to SA after thrombolysis with urokinase (500,000 u) and balloon re-expansion.
8. The treatment experience was.
① Firstly, with the help of the path of transfemoral arteriography, the soft tip of the O.035-inch superslip guidewire was used to repeatedly explore the potential gaps that may exist in the occluded segment, and the penetration of the occluded vessel could mostly be obtained. If the proximal end of the occluded segment is too close to the SA opening, the auxiliary 5F catheter can be placed as close to the SA opening as possible to facilitate the opening of the guidewire;
(ii) If the opening cannot be completed by the collateral route, a retrograde opening with a guidewire through the brachial artery can also be attempted. This approach can improve the opening rate of the lesion on the one hand, and on the other hand, it can avoid further enlargement of the arterial entrapment (which may occur during the opening of the guidewire) by the collateral flow after the opening;
(3) If the opening cannot be obtained, but the occluded segment is still short, the occluded segment can still be successfully penetrated with the hard end of the guidewire as instructed by the cascade and retrograde bi-directional angiography, as in the case of this study.
9. Due to the inherent anatomic relationship, the most serious complication that may arise when treating a diseased SA is distal arterial embolism, especially vertebral artery embolism and the resulting stroke. However, fortunately, due to the presence of SA steal signs, the plaque and thrombus that may be dislodged during the interventional operation do not easily enter the brain via the refluxed vertebral artery; in addition, the change of vertebral artery blood flow direction after SA opening is also delayed, and coupled with the meticulous operation of the operator, the incidence of this complication is extremely low. In recent years, there are still ipsilateral balloon temporary occlusion of vertebral artery blood flow and the application of brain umbrella and other measures, so that the technology becomes more perfect and safer.
10, SA stenosis, occlusion of the effective interventional treatment mainly includes PTA and internal stenting. The general principles of interventional treatment should also be followed in their application, that is, if PTA treatment is obviously effective, internal stenting should not be performed; if the stenosis of the vessel is still greater than 50% after PTA, stenting should be considered. In the present study, two cases were treated with PTA alone, and no recurrence of symptoms was observed during follow-up.
11.Indications: Most scholars believe that occlusion of the subclavian artery with insufficient blood supply to the vertebrobasilar artery or severe upper limb ischemia is an indication for surgery.
12.The Seldinger method is used to place a 5~7F arterial sheath, and a 5~7F pigtail catheter is sent along the femoral artery to the ascending aorta, and a high-pressure syringe is connected to perform a cephalobrachial trunk arteriogram to accurately measure the length and diameter of the stenotic segment, the diameter of the normal subclavian artery before and after the stenotic segment, and the distance from the stenotic segment to the opening of the vertebral artery. The subclavian artery was superselected using a Simmons catheter. The superslip guidewire was passed through the stenotic segment, and a dilation balloon of appropriate diameter and length (4-10 mm in diameter and 2-4 cm in length) was fed along the guidewire to dilate the stenotic segment and then the imaging was performed to see whether there was retraction and residual stenosis. In this group, self-expanding stents with diameters of 7~10mm and lengths of 2~4cm were used to precisely locate the stenosis and ensure that the vertebral artery was not covered, and the treatment effect was checked by re-imaging after release.
If the lesion involves the vertebral artery, it may be necessary to place a guidewire for protection, but since embolization of the vertebral artery rarely occurs, it is usually not necessary to place a thrombus protection device.
14.Stent selection
Stents can be divided into two main categories, balloon-expandable stents and self-expanding stents made of nickel-titanium alloy. The advantages of self-expanding stents are that they are not easily deformed by external forces and have good flexibility, but the disadvantage is that they are not precisely positioned and are mostly used for longer lesions. Depending on the vessel diameter, 7~10mm stents can be used, and post-expansion with balloons 1-2mm smaller than the stent diameter. The advantages of balloon-expandable stents are accurate positioning, and the disadvantages are easy deformation and poor flexibility by external force, which should be placed under sufficient pre-expansion to avoid displacement when the stent is released.
15. Complications
Common complications are bleeding at the puncture site, hematoma, pseudoaneurysm, arteriovenous fistula, and rare complications are subclavian artery rupture, thrombosis, and distal limb embolism. Stroke caused by vertebral artery embolism is rare because in patients with subclavian artery steal, the vertebral artery does not resume antegrade flow immediately after balloon opening of the subclavian artery, and it usually takes 20 seconds to 20 minutes for the vertebral artery to gradually return to antegrade flow, which may be the reason for the low incidence of stroke.