Keywords
superior vena cava obstruction syndrome - SVC obstruction - body floss technique
Introduction
Superior vena cava (SVC) syndrome is a clinical condition resulting from venous hypertension
secondary to SVC obstruction (SVCO).[1] Malignant etiology accounts for more than 90% of cases of SVCO, with bronchogenic
carcinoma accounting for at least 50%.[2]
[3] SVCO is seen in up to 4% of all diagnosed bronchogenic cancers, and squamous cell
carcinoma is the subtype most frequently associated with SVCO.[1]
[4]
Traditionally, malignant SVC syndrome is treated with radiotherapy and chemotherapy.[4] Endovascular stenting of the SVC has gained popularity and has become the treatment
of choice for acute symptomatic SVC syndrome when rapid symptomatic relief is desired.
Symptoms are usually alleviated within 24 to 72 hours after SVC stenting, unlike in
patients who would receive chemotherapy and/or radiotherapy where symptoms would take
at least 2 to 4 weeks to subside.[5] Traditionally, stenting of the SVC is achieved with a single venous access (usually
femoral venous access). However, dual venous access and body floss technique have
distinct advantages of superior control over the positioning and accurate deployment
of the stent. We report our experience with SVC stenting for malignant SVCO using
the body floss technique.
Materials and Methods
In this study, a retrospective analysis of patients who underwent stenting for malignant
SVCO from 1 March 2015 to 31 March 2020 was performed. Patients were followed up from
the day of the procedure until acquisition of latest information or death as an end
point. All data were collected from the integrated hospital information system, or
by contacting the patients telephonically wherever deemed necessary.
All patients had clinical symptoms and signs of SVC syndrome at the time of receiving
requisition for stenting by the clinical team ([Table 1]). All patients had either contrast-enhanced multidetector computed tomography (MDCT)
or positron emission tomography CT with contrast-enhanced CT component as a part of
an initial treatment workup. Length of obstruction, site of obstruction, venous diameter
above and below the obstruction, Stanford grade of obstruction and presence of collaterals
were noted on the cross-sectional imaging studies.[1] For stable patients, histological confirmation of malignancy was obtained. For unstable
patients, stenting was performed first, followed by biopsy when the clinical condition
improved. All patients received preprocedural hematological evaluation for platelets,
coagulation parameters, and renal function.
Table 1
Characteristic of patients
|
Characteristics
|
Values
|
|
Sex
|
|
|
Male
|
20
|
|
Female
|
5
|
|
Median age
|
65 y (34–78 y)
|
|
Causes of superior vena cava obstruction
|
|
|
Adenocarcinoma
|
11
|
|
Small cell carcinoma
|
7
|
|
Squamous cell carcinoma
|
2
|
|
Poorly differentiated carcinoma
|
1
|
|
Sarcoma
|
1
|
|
Metastatic disease
|
2
|
|
No histology
|
1
|
|
Stanford classification
|
|
|
Type 1
|
1
|
|
Type 2
|
11
|
|
Type 3
|
3
|
|
Type 4
|
10
|
|
Primary stenting (no treatment before stent)
|
14
|
|
Secondary stenting (received treatment before stent)
|
7
|
|
No treatment before or after stent
|
4
|
|
Number of stents placed
|
27
|
|
Single stent
|
23
|
|
Double stent
|
2
|
|
Stent diameter
|
|
|
16 mm
|
2
|
|
18 mm
|
8
|
|
20 mm
|
9
|
|
22 mm
|
7
|
|
24 mm
|
1
|
|
Average pretreatment Kishi score
|
6
|
Informed consent was obtained prior to the procedure. All patients underwent SVC stenting
under local anesthesia and monitored anesthesia care. Standard physiological monitoring
of vitals including the pulse, blood pressure, oxygen saturation, and electrocardiogram
was ensured during the procedure.
Technique
Venous access to right femoral vein and right internal jugular vein was obtained under
ultrasound guidance and a short vascular sheath (6F) was placed. Superior vena cavogram
was obtained using the jugular access to confirm the extent of venous stenosis/occlusion,
collateral formation, and coexisting thrombus. Using a 5F multipurpose catheter and
0.035” standard hydrophilic guide wire, the SVCC was crossed from above using fluoroscopic
guidance. After crossing the obstruction, the hydrophilic guide wire was positioned
in the lower segment of the inferior vena cava and snared through the femoral sheath.
Subsequently, the standard guide wire was exchanged for a 260 cm stiff Amplatz guide
wire with the soft tip exiting the jugular sheath. Once the dual-access (“through-and-through”
or “body-floss”) was established, the femoral vein sheath was exchanged for a 11 F
sheath and the rest of the procedure was performed through the femoral access ([Fig. 1]).
Fig. 1 Case of adenocarcinoma carcinoma with superior vena cava obstruction syndrome. (A) Computed tomography showing paratracheal mass infiltrating superior vena cava (arrow).
Extensive mediastinal collateral vessels can be observed (curved arrow). (B) Venogram showing occlusion (arrows) of the superior vena cava (type 4 Stanford)
with collaterals reforming the azygos vein (curved arrow). (C) Final superior vena cavogram obtained after stent placement shows free flow of contrast
material through the superior vena cava (arrow) and disappearance of all venous collaterals.
(D) Clinical image showing through and through access.
The stent size was chosen at 15 to 20% more than the reference vessel diameter on
MDCT. We placed ~60% of the length of the stent above the lesion so as to reduce the
risk of central stent migration. We placed the stent in between the superior normal
vein (landing zone of at least 10 mm margin) and SVC–right atrium junction inferiorly.
When bilateral brachiocephalic veins were occluded, the stent was placed through one
of the two brachiocephalic veins. Self-expanding stainless-steel stents (Wallstent,
Boston Scientific, Natick, Massachusetts, United States) were used in all patients.
All patients received an intravenous bolus of 70 IU/kg of heparin prior to the procedure.
Pre- or poststent dilation was not routinely performed. Prestent balloon dilation
was performed only if there was any resistance to the passage of the stent across
the obstruction (5/25). Poststent dilation was performed in those cases in which there
was no free flow of contrast material across the stent or in case of persistence of
collateral flow even after stenting (4/25).
Postprocedural Care and Follow-Up
In the postprocedure period, subcutaneous injection of enoxaparin sodium 60 mg was
given twice daily until discharge to prevent acute stent thrombosis (average 2 days).
All patients received aspirin 75mg/day and clopidogrel 75 mg/day for a minimum period
of 6 months following the procedure and aspirin lifelong.
After stenting, patients were evaluated for feasibility of specific antitumor treatment
by their treating physicians. Patients were followed for the resolution of the clinical
symptoms of SVCO. All patients underwent imaging follow-up as per the clinician’s
discretion to assess treatment response.
Study Design
The primary end point of our study was to assess for complete clinical success (defined
by a Kishi score of <2 at 48 hours after stenting), partial clinical success (Kishi
score between 2 and 4 at 48 hours after the procedure), or clinical failure (Kishi
score above 4). Secondary end point was to evaluate symptom recurrence-free survival,
time to recurrence, and overall survival. The complications of endovascular stenting
were also studied. Overall survival of patients undergoing primary stenting (no prior
antitumor therapy at the time of stenting but received adjuvant chemotherapy or radiotherapy
after stenting), patients undergoing secondary stenting (received prior antitumor
treatment), and in patients who received no antitumor treatment before or after stenting
were analyzed. Partial stent migration was defined as migration from initial position,
but still covering the stricture.
Results
Stent placement was successful in 24/25 patients (96%). In one patient, due to extensive
chronic thrombus and tandem lesions, we failed to cover entire length of obstruction
resulting in a technical failure. Complete clinical success was seen in 23/25 (92%)
patients. Clinical failure was noted in only one patient that was due to technical
failure ([Table 1]). Mortality rate of 4% (1/25) was noted due to SVC rupture in one patient. Partial
stent migration was noted in two patients, which was treated by placing another overlapping
stent. No clinical implications were observed due to stent migration.
Incidental stent occlusion due to stent thrombosis was seen in two patients within
8 hours after stenting. Both patients clinically responded to systemic anticoagulation
and showed clinical success at 48 hours. Follow-up imaging confirmed patency of the
stent. One case of delayed stent occlusion (at 60 days) due to tumor progression was
encountered. No secondary intervention was done in this case due to poor performance
status. The primary stent patency rate was 88% (22/25).
Median overall survival of 133 days was observed (range: 1–847 days). Median overall
survival of 149 days was observed in primary stenting patients, whereas in patients
who underwent secondary stenting, the median survival was 47 days. Median survival
of patients who were not fit for any cancer specific treatment after stenting was
8.5 days. Five patients were still alive at the end of the study period ([Fig. 2]).
Fig. 2 Kaplan–Meier curves. (A) Overall patient survival. (B) Survival curve of group 1 (primary stenting), group 2 (secondary stenting), and
group 3 (no cancer treatment after stenting).
Discussion
Management of thoracic malignancies with SVCO depends on multiple factors such as
type of malignancy, stage of malignancy, severity of symptoms, and patient’s performance
status and comorbidities.[5] Kishi scoring system and Yu et al’s classification system serve as a guide to identify
those patients who require palliative stenting at any stage of treatment.[5]
[6] Kishi score above 4 is an indication for SVC stenting.[7] If SVCO symptoms are life threatening, SVC stenting can be done before establishing
the histopathological diagnosis. Stenting may not be used as the first-line treatment
option for symptomatic patients with SVC syndrome caused by small cell lung cancer,
non-Hodgkin lymphoma, and germ cell tumors since these tumors are chemosensitive and
deserve a trial of chemotherapy.[5]
[8]
Technical Success
Our technical success rate of 96% is consistent with the technical success observed
in previous studies.[9]
[10]
[11]
[12] We failed to connect normal to normal zone in one case, due to extensive thrombus
extending to both brachiocephalic veins and internal jugular vein, which eventually
also showed thrombosis. In the patients with acute thrombus, catheter-directed intravascular
thrombolysis can be attempted. Thrombolysis helps to reduce the thrombus load and
the length of the obstruction. The thrombolysis is most effective if it is started
within 2 to 5 days of onset of symptoms and tends to be ineffective if started after
10 days.[4]
[13] We did not attempt thrombolysis in this case due to chronic and extensive nature
of thrombus.
Clinical Success
Immediate clinical success was achieved in 92% (23/25) of cases. If the technical
failure and postprocedure mortality cases are excluded, symptomatic relief was achieved
in all other cases, which translates to 100% conversion of technical success into
clinical success. In comparison, available literature reports a clinical success rate
of 50 to 70% with radiotherapy and takes 2 to 4 weeks for symptomatic relief.[5]
[14]
[15] A meta-analysis of prospective and retrospective studies from 1983 to 1997 for small
cell lung cancer found that chemotherapy could achieve symptomatic relief in up to
76.9% cases.[5]
Unilateral versus Bilateral Stenting
Unilateral stents were placed in all cases, even in those with bilateral brachiocephalic
vein obstruction. Our study also reinforces the arguments from Dinkel et al that unilateral
placement of stent will suffice irrespective of type of SVCO.[8]
[16] Unilateral stenting is technically more simple, is more cost-effective, is associated
with far lower complication, and has similar outcomes as compared with bilateral stenting.[16]
Recurrence Rate and Reintervention
Out of the 23 patients who underwent successful stenting without any major complication,
22 (95%) patients were free from symptoms due to SVCO till death or up to March 2020.
This is very well aligned with the primary patency rate of 86 to 93% reported in the
literature.[8] Two cases of immediate stent thrombosis successfully responded to routine anticoagulation
therapy. One case of recurrent SVCO due to tumor progression was observed in our series.
We did not perform any reintervention in this case due to the patient's poor general
condition.
Overall Survival
Median survival of 133 days was noted in our series. SVC stenting patients have a
dismal prognosis with median survival ranging from 1.5 to 10 months, irrespective
of any treatment received.[5]
Effect of Adjunct Chemotherapy and/or Radiotherapy on Overall Survival
Patients who underwent primary stenting followed by chemotherapy and/or radiotherapy
lived longer than patients who did not receive any treatment after stenting. Interestingly,
literature suggests that patients who received chemotherapy and/or radiotherapy prior
to stenting were likely to die early as compared with patients who received primary
stenting.[8] Similar observation was also made in our series. The most plausible explanation
in favor of this would be that secondary stenting cases represent primary treatment
failure with chemotherapy and/or radiotherapy (progressive disease).
Mortality and Morbidity
A single mortality due to pericardial tamponade was observed in our series (4%), which
manifested 2 hours after the procedure ([Fig. 3]). The risk factors for cardiac tamponade are vascular fragility due to prior radiotherapy
or chemotherapy, perforation caused by wire during crossing, excessive balloon dilation,
and large stent diameter.[17]
Fig. 3 Pericardial tamponade post-stenting in a case of superior vena cava (SVC) obstruction
due to adenocarcinoma lung. (A, B) Computed tomography and positron emission tomography images showing large mass in
right mediastinum infiltrating the SVC (arrows). (C) Venogram showing large filling defects in SVC (arrow). (D) Final superior vena cavogram obtained after stent placement (24 mm) showing distal
end of stent (curved arrow) is above cavoatrial junction (star). Note the danger zone
of SVC (bracket).
Approximately, distal 3.5 cm of the SVC is not covered by serous pericardium. This
“danger zone” should be avoided as a “landing zone” for stents, since this segment
is prone for rupture.[17] The stent margin is free and sharp that might protrude outside the wall particularly
when stents are oriented obliquely. In our case, larger stent diameter (24 mm) and
distal end of stent in the danger zone were the likely causes of SVC rupture.
Two cases of partial stent migration were seen in our series (8%). This happened when
we tried to place a short length Wallstent ([Fig. 4]). After differential foreshortening at the upper end, the stent migrated below the
stenosis. We placed a second larger stent to anchor the migrating stent and also to
cover the stenosis. Various strategies are described to manage stent migration. Retrieving
the stent using a snare for a fully migrated stent is desirable.[18] By avoiding routine pre- and post-balloon dilation and hoping that residual stenosis
anchors the stent, stent migration can be prevented.[18]
Fig. 4 Stent migration in case of adenocarcinoma with superior vena cava (SVC) obstruction
syndrome. (A) Superior vena cavogram shows high-grade SVC stenosis (arrow). (B) Image shows prerelease stent position in relation to venous stenosis (arrow). The
upper end of the stent is in the right brachiocephalic vein (star). (C, D) Progressive stent migration (arrow) from initial position (star). (E) Migrating stent (arrow) is stabilized using a longer stent (curved arrow).
Apart from giving stability and pushability during crossing the lesion, the body floss
technique comes in handy in case of stent migration, since the stent is still held
over the wire.[18] In case of stent migration, this technique not only prevents major cardiac events
by preventing stent migration to the right ventricle but it also gives sufficient
time as well as stability and strong scaffold for stent retrieval. In case of SVC
rupture, the body floss technique provides stable access to place the balloon tamponade/covered
stent graft. Literature shows body floss technique is used only during difficult access
cases.[13] In our experience, routine use of body floss technique adds to the confidence of
the operator during the procedure and the operator is better prepared handling the
potentially fatal complications. Complication rate up to 19% is reported in the literature;
hence, body floss technique can make a difference in one-fifth of patients.[13]
Conclusion
A high technical and clinical success is achieved with endovascular stenting of the
SVC for highly symptomatic malignant SVCO. Unilateral stenting is sufficient in most
cases. Body floss technique is very helpful during the procedure and helps manage
stent related complications.
