Venous · IR Playbook

Venous Thoracic Outlet Syndrome Catheter-Directed Thrombolysis and Venoplasty (-)

Catheter-directed thrombolysis (CDT) with adjunctive balloon venoplasty is the initial endovascular limb of the multidisciplinary treatment of venous thoracic outlet syndrome (Paget-Schroetter syndrome), in which repetitive costoclavicular compression produces subclavian vein injury, fibrosis and effort thrombosis in young active patients. CDT restores luminal patency and unmasks the underlying extrinsic compression and intrinsic stenosis, but it is not definitive therapy: anticoagulation or lysis alone carries a high rethrombosis rate, and durable outcome requires subsequent thoracic outlet decompression. Thrombolysis is most effective when instituted within about two weeks of symptom onset, before the thrombus organises. Stenting before surgical decompression is contraindicated because the stent is crushed or fractured by the intact costoclavicular space.

Learning objectives

• Describe the boundaries of the costoclavicular space and explain why the subclavian vein is the structure compressed in venous thoracic outlet syndrome
• Distinguish primary effort thrombosis from secondary catheter-related upper-extremity DVT and state how this changes management
• Define the time window and patient selection criteria for catheter-directed thrombolysis in venous thoracic outlet syndrome
• Perform basilic access, thrombus traversal, infusion catheter placement and monitored lytic infusion
• Justify why venoplasty is performed but stenting is avoided before thoracic outlet decompression
• Recognise and manage the haemorrhagic and thrombotic complications of upper-extremity CDT

Indications

• Acute primary axillosubclavian vein thrombosis (Paget-Schroetter syndrome) of less than approximately 14 days duration in a functionally active patient
• Disabling arm swelling, heaviness, cyanosis or venous claudication attributable to axillosubclavian occlusion
• Selected subacute effort thrombosis where residual soft thrombus is demonstrated and the patient is a candidate for subsequent decompression
• Rethrombosis after thoracic outlet decompression, where lysis is used to restore the lumen before repeat venoplasty
• Residual or recurrent symptomatic stenosis after decompression, treated by venography and balloon venoplasty without antecedent lysis

Absolute contraindications

• Active internal haemorrhage
• Any history of intracranial haemorrhage
• Known intracranial neoplasm, aneurysm or arteriovenous malformation
• Intracranial or intraspinal surgery, or significant head trauma, within the preceding 3 months
• Ischaemic stroke within the preceding 3 months
• Suspected aortic dissection

Relative contraindications

• Major surgery, organ biopsy or non-compressible vascular puncture within the preceding 10 days
• Recent gastrointestinal or genitourinary bleeding
• Uncontrolled hypertension
• Severe thrombocytopenia, coagulopathy or hepatic failure
• Pregnancy or the early postpartum period
• Bacterial endocarditis or pericarditis
• Diabetic haemorrhagic retinopathy
• Thrombus older than about 2 weeks, where lytic yield is low and procedural bleeding risk is unchanged

Equipment

• High-frequency linear ultrasound transducer, 7–15 MHz, with sterile sheath
• Micropuncture set with 21 G needle and 4–5 Fr transitional dilator
• 5–6 Fr short vascular sheath; 7–8 Fr sheath if aspiration thrombectomy is planned
• 0.035 inch angled hydrophilic guidewire and 0.035 inch stiff working guidewire, 180–260 cm
• 4–5 Fr angled hydrophilic selective catheter, 65–100 cm, for traversing the occlusion
• Multi-sidehole infusion catheter with 10–50 cm infusion length and matching occluding wire
• Alteplase for infusion, plus unfractionated heparin for the sheath side-arm
• High-pressure non-compliant balloon catheters, 8–14 mm diameter, 20–40 mm length
• Inflation device with pressure gauge and dilute contrast
• Aspiration thrombectomy or pharmacomechanical thrombectomy system if adjunctive debulking is planned
• Digital subtraction angiography suite with the capability for positional and provocative imaging of the abducted arm

Procedure steps

1. Re-verify the symptom onset date, confirm primary rather than catheter-related thrombosis, and recheck laboratory parameters and contraindications on the day of the procedure. Ensure a monitored bed and a vascular surgical plan for subsequent decompression are in place before the lytic infusion is started.
2. Position supine with the affected arm abducted on an arm board. Under ultrasound guidance, puncture the basilic vein in the mid-upper arm with a 21 G micropuncture needle and place a 5–6 Fr sheath. Basilic access lies medial and away from the brachial artery and median nerve and gives a straighter course into the axillary vein.Pearl: Choose an access site distal enough to allow the entire thrombus to be spanned by a single infusion segment.
3. Inject contrast through the sheath and image from the axillary vein to the superior vena cava in the neutral position. Define the proximal and distal thrombus extent, the collateral network across the shoulder girdle, and any internal jugular or brachiocephalic involvement.Pearl: A dense collateral network around the shoulder implies chronicity and predicts a poorer lytic response.
4. Advance an angled hydrophilic 0.035 inch guidewire supported by a 4–5 Fr angled catheter through the thrombus into the superior vena cava. Confirm intraluminal position by aspiration and gentle contrast injection before exchanging for a stiff working wire.
5. Exchange for a multi-sidehole infusion catheter whose infusion length spans the entire thrombus from the axillary vein to the central end of the clot. Secure the catheter and sheath carefully to the arm to prevent migration during the infusion.Pearl: Choosing an infusion length slightly longer than the measured thrombus avoids untreated segments at either end.
6. Start alteplase through the infusion catheter, typically at 0.5–1 mg/h, with low-dose unfractionated heparin through the sheath side-arm. Nurse the patient in a monitored unit with hourly neurological and access-site observation and repeat haemoglobin, platelets and fibrinogen every 6–12 h.Pearl: Any new headache, altered consciousness or focal neurological deficit mandates immediate cessation of lysis and urgent non-contrast head CT.
7. Return the patient to the angiography suite at 12–24 h. Reimage the whole segment, advance or retract the infusion catheter to cover residual thrombus, and continue or stop the infusion based on the interval response.
8. For large-volume or lysis-resistant thrombus, or when bleeding risk mandates a shortened infusion, use aspiration or pharmacomechanical thrombectomy through an upsized 7–8 Fr sheath to debulk the clot and shorten total lytic exposure.Pearl: Mechanical debulking is particularly useful in patients in whom prolonged lysis is undesirable.
9. Once the thrombus has cleared, the underlying fibrotic subclavian vein stenosis at the costoclavicular junction becomes visible. Dilate with a high-pressure non-compliant balloon sized 8–14 mm to the adjacent normal vein, with slow inflation to nominal or rated pressure and careful attention to waist resolution.Pearl: A persistent waist that recoils immediately is characteristic of extrinsic costoclavicular compression and is an argument for decompression rather than more aggressive dilatation.
10. Repeat venography with the arm in neutral position and then in abduction and external rotation. Document dynamic narrowing or occlusion of the subclavian vein at the costoclavicular space, which confirms the extrinsic component and supports the surgical indication.Pearl: Positional imaging is the endovascular evidence that decompression, not more endovascular therapy, is the definitive treatment.
11. Do not place a stent in the retroclavicular subclavian vein before thoracic outlet decompression. Stents deployed into an undecompressed costoclavicular space are subject to repetitive crush and have a high rate of deformation, fracture and occlusion.
12. Remove the infusion catheter and sheath, achieve haemostasis with compression, and resume therapeutic anticoagulation once haemostasis is secure. Communicate the venographic findings, the residual stenosis and the positional compression directly to the vascular surgical team and arrange definitive decompression.Pearl: A clear, annotated description of the lesion length and its relationship to the first rib and clavicle is the most useful thing the interventional radiologist gives the surgeon.

Complications

• Access-site haematoma or oozing
• Major systemic haemorrhage
• Intracranial haemorrhage
• Pulmonary embolism
• Venous rupture or extravasation during venoplasty
• Early rethrombosis
• Stent deformation, fracture or occlusion
• Heparin-induced thrombocytopenia
• Contrast-induced nephropathy or contrast reaction

Exam pearls

• The subclavian vein is the only structure of the three that passes anterior to the anterior scalene; this is why venous TOS is a costoclavicular disease while neurogenic and arterial TOS are interscalene diseases.
• Paget-Schroetter syndrome is primary effort thrombosis of the axillosubclavian vein in a young active patient; the pathology is repetitive costoclavicular compression producing intimal injury and fibrosis.
• The therapeutic triad is thrombolysis, thoracic outlet decompression, and venoplasty of residual stenosis; omitting decompression predicts rethrombosis.
• Duplex ultrasound cannot reliably interrogate the retroclavicular subclavian vein, so a negative duplex does not exclude the diagnosis.
• Never stent the subclavian vein before first rib resection, because an undecompressed costoclavicular space crushes and fractures the stent.
• Provocative positional venography with the arm abducted and externally rotated is the endovascular demonstration of the extrinsic compression that justifies surgery.
• Minimum anticoagulation for primary upper-extremity DVT is 3 months, per the CHEST 2021 guideline.

Viva questions

Which space is compressed in venous thoracic outlet syndrome, and what are its boundaries?

The costoclavicular space, bounded superiorly by the clavicle and subclavius muscle, inferiorly by the first rib, anteriorly by the costoclavicular ligament, and posteriorly by the anterior scalene muscle. The subclavian vein is compressed here because it is the only one of the three neurovascular structures that passes anterior to the anterior scalene.

Why is thrombolysis alone inadequate treatment for Paget-Schroetter syndrome?

Lysis clears the thrombus but does not address the underlying costoclavicular compression and the fibrotic intrinsic stenosis that caused it. Anticoagulation or lysis without decompression carries a high rate of rethrombosis and persistent symptoms, so lysis is the first stage of a staged pathway that ends in thoracic outlet decompression.

What is the time window for effective catheter-directed thrombolysis and why?

Roughly 14 days from symptom onset. Beyond this, the thrombus becomes organised and adherent, plasminogen content falls, and lytic response drops sharply while the bleeding risk remains unchanged.

Why should a stent not be placed in the subclavian vein before decompression?

The retroclavicular subclavian vein sits in a mobile bony vice between the first rib and clavicle. A stent placed while that space is intact is subject to repetitive crush with arm movement, leading to deformation, fracture and occlusion, and it complicates any subsequent surgical reconstruction. Urschel and Patel specifically documented the failure of intravenous stents in this setting.

How would you distinguish primary effort thrombosis from secondary upper-extremity DVT, and why does it matter?

Primary effort thrombosis occurs in young, active patients with repetitive overhead activity and no indwelling device, with positional compression at the costoclavicular junction. Secondary thrombosis is associated with central catheters, pacemaker leads or malignancy. Only the primary form is treated with the lysis plus decompression pathway; secondary disease is usually managed with anticoagulation and device management.

A duplex ultrasound is reported as normal but you strongly suspect effort thrombosis. What do you do?

Duplex is limited in the retroclavicular segment where the clavicle blocks the acoustic window, so a negative study does not exclude the diagnosis. Proceed to CT or MR venography, or to catheter venography with positional imaging, if clinical suspicion remains high.

You have cleared the thrombus and a tight waist at the costoclavicular junction recoils immediately after 12 mm balloon dilatation. What is your next step?

Accept the result and refer for decompression. Immediate recoil indicates extrinsic bony compression rather than a dilatable intrinsic lesion. Escalating balloon size risks venous rupture and stenting risks crush; the definitive treatment is first rib resection with venolysis.

Which access site do you prefer for upper-extremity CDT and why?

Ultrasound-guided basilic vein access in the mid-upper arm. It is superficial, medial to the brachial artery and median nerve, and gives a straight course into the axillary vein, unlike the cephalic vein which turns acutely at the deltopectoral groove.

References