This study highlights promising early to mid-term outcomes of venous stenting in the thoracic outlet for patients that present with vTOS. As it is a condition that predominately affects a younger population, it can lead to significant morbidity in patients who are not treated affecting their long-term functional ability. Treatment is paramount when the dominant hand is affected. Treatment algorithms involving early CDT and adjuvant thoracic outlet decompression as a treatment modality is associated with significant improvements in long term outcomes (Rutherford 1998). Our results, although in a small number, suggest however that there could be a role for adjuvant therapies including follow-up venography with percutaneous transcutaneous angioplasty (PTA) and venous stenting for patients with residual stenosis on duplex ultrasonography. The residual stenosis is likely caused by endothelial fibrosis similar to that found in May-Thurner syndrome. Similar to the pelvic veins, these residual venous lesions are refractory to angioplasty alone as there is a high rate of recoil (Figs. 3 and 4). Leaving such lesions may therefore increase the risk of recurrent thrombosis despite decompression of the thoracic outlet. We therefore advocate venous stenting to be beneficial by increasing the luminal diameter and maintaining flow through diseased axial veins.
There is some anecdotal evidence that there is an unacceptably high risk of stent fracture secondary to the dynamic compression of the stent with abduction of the arm, even after rib resection. We have seen this with one stent type as shown in Fig. 5, however, our experience with the older Cook® Zilver Vena™ and the current generation specific venous stent, the Bard® Venovo™ Venous Stent has not had this problem albeit with a short follow-up period. These open cell stents that have been designed to have crush resistance within the post-thrombotic vein while still maintain flexibility.
The ideal stent design in this region should conform to the tortuous anatomy, accommodate the free range of shoulder movement and withstand compression with a high radial force. Although there are no dedicated venous stents for the thoracic outlet, we have had much success with the current generation dedicated venous self-expanding nitinol stents. Typically, the stent sizes required are around 14 mm in diameter, accommodating the size of the axillary and subclavian vein. The length of the stent required needs to completely cover the damaged segment of vein with the same principles applied to pelvic veins applied to this anatomical area. Use of intravascular ultrasound (IVUS) here can be very beneficial as seen within the pelvic system. The use of IVUS at our institution was at the discretion of the operating surgeon. The main benefits included accurate demonstration of the diseased segment and true luminal diameters allowing appropriate length and diameter stent sizing. Treatment of this segment hinges on ensuring adequate outflow and inflow and achieving appropriate luminal cross-sectional area.
With the Cook® Zilver Vena™, stenting was possible from the arm due to the 7 french sheath required. With the newer dedicated venous stents such as the Bard® Venovo™ a 9 french sheath is required is required for access. This required a change to a femoral approach. Most cases required either an arm or femoral vein puncture depending on the stent used, however, access through the lesion from a dual approach from basilic/brachial and femoral veins was also employed when lesions were challenging to cross. This flossing technique provides a stable platform when delivering balloons and stents. As with iliac lesions, pre and post-dilatation of the vessel to the stent size was performed to ensure adequate stent opening and decent luminal diameter.
After stent placement our patients were therapeutically anticoagulated for at least 3 months using a vitamin K antagonist or a direct thrombin inhibitor to prevent thrombosis in areas where there has been prior luminal damage. Following this we recommended lifelong aspirin. We used an aggressive post-operative surveillance with ultrasound performed 6 weeks, 3 months, 6 months and 12 months post intervention provided there was no change in symptoms.
Our study has demonstrated relief of symptoms in 88% of patients during follow-up. In 1993, Machelder published an algorithm of treating vTOS with early CDT and rib resection. He demonstrated that 93% of patients with patent axillo-subclavian veins after first rib resection were symptom-free at a mean follow-up of 3.1 years and that only 64% were symptom-free if the vein had occluded (Machleder 1993). Our results are comparable to Machelder and highlights the importance of achieving venous patency with reconstruction and strict follow-up.
There are several limitations of this study including the limitations of retrospective data collection, small sample size and limited follow up time. The small numbers found in this study is not uncommon to other literature regarding vTOS. However, this lack of power makes it difficult to reach firm conclusions regarding the effectiveness of adjunctive venous thoracic outlet stenting. Multicenter, prospective trials over a longer period of time are therefore needed to fully evaluate the impact of this proposed management strategy. Although there is no evidence available for the optimal management of vTOS, our study demonstrats that our treatment algorithm involving adjunctive venous stenting should be considered in selected patients.