|Year : 2017 | Volume
| Issue : 2 | Page : 73-75
Giant subclavian artery aneurysm: Case report and review of literature
Yashpal Singh1, Himanshu Verma2, Ramesh Tripathi1
1 Narayana Institute of Vascular Sciences, Narayana Hrudayalaya, Bengaluru, Karnataka, India
2 Division of Vascular Surgery, Mayo Clinic, Rochester, USA
|Date of Web Publication||5-May-2017|
Narayana Institute of Vascular Sciences, Narayana Hrudayalaya, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Upper extremity aneurysms are quite uncommon when compared to other peripheral arterial aneurysms. Among them, giant (>5 cm) subclavian artery aneurysms (SCAAs) are extremely rare. We report a case of giant SCAA measuring 8.8 cm in its maximal diameter with an updated review of literature. Our case is unique in view of surgical exposure method used (modified trapdoor thoracotomy with claviculectomy).
Keywords: Aneurysm, subclavian artery, trapdoor thoracotomy
|How to cite this article:|
Singh Y, Verma H, Tripathi R. Giant subclavian artery aneurysm: Case report and review of literature. Indian J Vasc Endovasc Surg 2017;4:73-5
| Introduction|| |
True subclavian artery aneurysms (SCAAs) are usually due to degenerative conditions, connective tissue disorders, or related to thoracic outlet syndrome (TOS). Pseudoaneurysms are more often due to blunt or penetrating trauma. Giant true SCAA (>5 cm) is rare. Very few case reports of large intrathoracic SCAA have been reported in the literature.
| Case Report|| |
A 77-year-old farmer presented with diffuse swelling in the right supraclavicular area, worsening hoarseness of voice, and dyspnea over 5 months duration. Computed tomography (CT) angiogram revealed a giant aneurysm of the right subclavian artery (SCA) just distal to its origin from innominate artery measuring 8.8 cm in its maximal diameter with massive displacement of mediastinum to the left side compressing trachea and upper lobe of the right lung. The right vocal cord had minimal movement on indirect laryngoscopy [Figure 1]a and [Figure 1]b. The right vertebral artery was occluded, and infraclavicular part of SCA was normal.
|Figure 1: Computed tomography angiogram showing giant right subclavian artery aneurysm (a) axial view, (b) three-dimensional reconstruction|
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Under general anesthesia, median sternotomy was performed for the patient. Mediastinal fat and thymus were dissected and pericardium exposed. A giant right subclavian aneurysm was noted arising from proximal one-third of the artery with a short proximal and long distal segment lying just behind the right clavicle with displacement of apex and middle lobes of the right lung. The right phrenic and recurrent laryngeal nerves were identified in front of the SCA and carefully looped and protected.
Due to the enormous size of aneurysm in a tightly packed thoracic outlet space and most of the right mediastinum, clavicle was divided in the middle to gain better exposure and access to the aneurysm (open-book approach). Proximal and distal clamps were applied, and aneurysmectomy and interposition graft with 6 mm InterGard Silver (Maquet Cardiovascular, Wayne, NJ, USA) was performed [Figure 2]a and [Figure 2]b. Although the postoperative recovery was delayed due to slow ventilator wean off, partially because of his vocal cord palsy, he made a full recovery and was discharged on day 9. Postoperative indirect laryngoscopy revealed no improvement in his vocal cord function, and he was subsequently treated by Teflon injection laryngoplasty. The right upper limb pulses were well felt with no blood pressure differential with opposite arm. There was also no residual motor and sensory deficit in the right upper limb.
|Figure 2: Exposure of subclavian artery aneurysm by trapdoor thoracotomy (a) and aneurysm repair (b)|
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| Discussion|| |
Aneurysms of the SCA are extremely rare. Only 1% of all peripheral aneurysms involve the subclavian and innominate arteries. Dent et al. have reported that only 2 out of 1488 cases of atherosclerotic aneurysm had SCAA, with an incidence of about 0.13%. The largest aneurysm thus far reported measured 12 cm.
Vierhout et al. in a 2010 review found <400 cases of SCAA published reports in the world literature.
SCAA s can be classified into two groups: (a) intrathoracic and (b) extrathoracic., Vierhout et al. found 39% of SCAAs in the proximal segment, 25% in the middle segment, and 24% in the distal segment. Each group differs with the other in etiology, presentation, and treatment. The etiology was trauma (37%), atherosclerosis (18%), TOS (18%), and iatrogenic (10%).
Proximal and middle segment SCAAs were most often caused by atherosclerosis, collagen disorders, and trauma or iatrogenic insults. TOS accounted for almost 15% of cases in the mid segment and almost half in the distal SCAs (46%).
Extrathoracic aneurysms are often related to a TOS or old trauma, intrathoracic aneurysms are often caused by atherosclerotic (as in our reported case) or rarely due to fibrodysplastic, infectious, or traumatic etiologies.
Extrathoracic aneurysm usually presents with pulsatile mass over supraclavicular fossa with or without vascular bruit whereas intrathoracic aneurysm or poststenotic aneurysm compress brachial plexus or upper extremity vessels leading to the edema.,, These aneurysms may erode into the apex of the lung and cause hemoptysis and compress recurrent laryngeal nerve resulting in hoarse voice, vocal cord paralysis, or dysphagia due to esophageal compression.,, Severe respiratory distress caused by tracheal compression has been rarely reported.
Embolization, rupture, and thrombosis causing ischemic limb were present in 16%, 9%, and 6% of patients, respectively. Finally, some aneurysms can be diagnosed after a rupture causing fatal hemorrhage presenting as massive hemothorax and shock.
Aneurysms of the distal part of the SCA are frequently associated with TOSs which present as poststenotic dilatation. Unlike visceral and aortoiliac aneurysms which may lead to rupture, the upper extremity aneurysms usually present as acute thromboembolic episodes, neuromuscular, or sensory dysfunctions resulting from pressure on the brachial plexus, thromboembolic episodes causing neurologic deficits, etc.
The chest CT can detect this condition noninvasively; however, CT or digital subtraction angiography is necessary to plan surgical or endovascular repair. Multiplanar reconstruction of CT angiogram is very helpful in planning the approach for the surgery.
The surgical or endovascular principle is to restore inflow and outflow tracts, which would benefit by exposing bilateral ends of aneurysm.
Common surgical approaches include (1) posterolateral thoracotomy, (2) third anterior intercostal space thoracotomy (thoracic), (3) T-shaped median sternotomy with transverse extension over the second or third intercostals space, (4) trapdoor thoracotomy (combination of 3 plus supraclavicular incision), and (5) paraclavicular incision. In our case, as the aneurysm was huge with severe inflammatory adhesions to the lung and retrosternal tissues, a modified trapdoor thoracotomy with division of clavicle was used for extensive exposure. Claviculectomy permitted excellent exposure for distal SCA, especially in trauma and complex SCA surgery.,
During the operation, it is generally recommended to expose proximal and distal ends of SCA first and then handle the aneurysmal body. In our case, there was a 1 cm stump of the right SCA available to clamp proximally followed by opening of the aneurysm removal of mural thrombus and Fogarty balloon control of the distal SCA. The aneurysm was excised in toto after dissection of distal end for application of a vascular clamp. There is usually a large cavity left after resection of a giant subclavian aneurysm and this requires pleural and mediastinal drainage till full lung expansion is achieved. The overall complication rate was reported to be 26% in the 2010 review by Vierhout et al., of 329 patients who underwent open surgery. There was an overall mortality of 5%, and a variety of complications, including laryngeal nerve palsy, upper limb ischemia, pulmonary problems, (including chylothorax and esophagopleural fistula), cardiac complications, graft occlusion, and brachial plexus injuries. Treatments that were performed in an elective setting had a mortality rate of 3%, and for the one-fifth of patients who had surgery in an emergency setting, the mortality rate was 13%.,
The clavicle is repaired by K-wires or plate and screw, ensuring the graft is not injured in the process of thoracotomy closure.
SCAAs should be treated when encountered; there are no criteria for size, and SCAAs can be well treated with both open and endovascular techniques. There are still currently <100 reports of endovascular SCAA repair in the literature, with the overall complication rate for endovascular SCAA repair was 28% with a mortality rate of 5%. The durability of endovascular techniques is not yet proven. Beregi et al. found that 40% of SCAA stent grafts were occluded within 1 year.
| Conclusion|| |
Although subclavian aneurysms are rare, their management remains primarily surgical due to proximity of major branches. Anterior trapdoor thoracotomy with claviculectomy provides excellent exposure for unhindered excision and reconstruction of large SCAAs.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]