WHAT ROLE DOES ENDOVASCULAR INTERVENTION PLAY IN MANAGING PSS?
Once the diagnosis of PSS is confirmed via history, physical exam, and imaging (such as X-ray of the thoracic inlet, duplex ultrasonography, or venography), holistic treatment typically proceeds in several stages, beginning with thrombolysis, followed by surgical decompression, and finally adjunctive angioplasty or venous bypass in certain cases.4
At this juncture, it is worth noting that a hybrid endovascular/open decompression approach is not always taken. Depending on local guidelines, patient characteristics, and myriad factors, the managing clinician may opt to proceed with only endovascular intervention or only open decompression. An approach employing both endovascular techniques alongside open decompression is associated with 100% technical success rates, and high rates of event-free survival.6 Zurkiya et al. emphasise that timely endovascular lysis or debulking of the thrombus is a well-documented contributing factor to the preservation of long-term luminal patency, and to the mitigation of re-occlusion, scarring, and intimal fibrosis.7 Further, Koury et al. suggests that surgical decompression may not be required if complete lysis is achieved via thrombolysis and there remains no evidence of residual stenosis or re-thrombosis.8
The endovascular management of PSS is chiefly centred on either CDTL or endovascular thrombectomy. Koury et al. describe the surgical technique for CDTL in upper extremity DVT (UEDVT) as beginning with gaining venous access in the ipsilateral upper extremity.8 Venography is carried out to determine the extent of thrombosis. The guidewire is then crossed over the lesion, to allow the infusion catheter to be introduced as near the lesion as possible. Thrombolytic agents such as tissue plasminogen activator or urokinase is then infused for a duration of at least 8 hours, or in some cases up to 72 hours. Patient fibrinogen levels and subclavian vein patency are monitored continuously. Catheter-related thrombosis can be prevented via infusion of a subtherapeutic dose of heparin. Koury et al. further note that CDTL is often augmented with mechanical thrombectomy, angioplasty, or endovascular stent placement to correct factors such as underlying stenosis.8
Intriguingly, Landry et al. note that CDTL is often associated with prolonged treatment durations and adverse events including cerebral haemorrhage, pulmonary embolism, and access site bleeding. As a result, mechanical thrombectomy using devices such as the AngioJet used with the power pulse spray technique are being increasingly employed to tackle PSS (as opposed to iliofemoral DVTs).4
The AngioJet utilises a perforated catheter tip through which high-velocity, high-pressure streams of saline are projected. The resulting local region of low pressure allows entrapment and retrieval of bulky thrombi via the Venturi-Bernoulli effect.9, 10 Though this system has historically been used more extensively for thrombus debulking in acute coronary syndromes and iliofemoral DVTs, Schneider and colleagues suggest the use of the AngioJet system in the setting of PSS is promising - they report an average treatment time of 12 hours overall, a significant reduction in comparison to that of CDTL.11
Completion of thrombolysis via endovascular intervention is then typically followed by surgical decompression of surrounding anatomical structures, before further adjunctive endovascular measures are implemented. Aggressive angioplasty prior to surgical decompression is generally discouraged, to prevent inflicting barotrauma to the wall of the SV while under anatomical compression.