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Paper text:
superior vena cava ( svc ) syndrome is a common complication of malignancy , particularly in lung cancer .
it is evident in 4% of lung cancer patients at diagnosis ( 1 ) , and it may also develop during the disease course .
patients with malignant svcs are typically seriously ill , and further deterioration is likely , due to the presence of unresectable advanced malignant tumors .
although bypass surgery has been reported for palliative treatment of malignant svcs in selected patients ( 2 ) , this type of surgery in terminally ill patients is difficult to justify and rather invasive for a palliative procedure . until recently ,
radiotherapy and chemotherapy were standards in the management of malignant svcs ( 3 , 4 ) .
however , both therapies may not be possible under certain conditions , especially when the cumulative maximum dosage has been reached in previous treatments . in addition , it may take several weeks before either intervention shows a clinical effect ( 5 ) .
endovascular stent placement as an alternative palliative treatment has increased because it is fastest way to relieve symptoms ( 6 ) .
many studies have reported the efficacy of stent placement in patients with malignant svcs ( 7 - 10 ) .
a few reports have described stent - graft placement in recurrent svcs after bare metallic stent placement or iatrogenic injury of the svc ( 11 - 14 ) . however , initial placement of stent - grafts for the treatment of malignant svcs has not been reported .
thus , we report on successful outcomes after the placement of stent - grafts for two patients who had malignant svcs caused by squamous cell carcinoma .
a chest radiograph showed an ill - defined mass in the right upper lung field . computed tomography ( ct ) revealed an ill - defined infiltrating central mass with mediastinal lymphadenopathy .
histology confirmed the diagnosis of squamous cell carcinoma and consequently , the patient underwent four cycles of chemotherapy for two months .
the patient then presented with swelling of the face and severe dyspnea for a week .
subsequent ct demonstrated progression of the mass , obstruction of the svc , confluence of both brachiocephalic veins ( fig .
although thrombolysis of the right brachiocephalic thrombosis and subsequent bilateral stenting could be performed , there was a risk of complications following thrombolysis because of the patient 's advanced age .
we thus decided on the unilateral placement of a triple - layered stent - graft ( vascular comvi stent - graft , taewoong medical , gimpo , korea ) that was 5 mm long at both bare extensions ( fig .
the triple - layered stent - graft was composed of two uncovered nitinol self - expanding metallic stents and an expanded polytetrafluoroethylene ( eptfe ) membrane between two uncovered stent layers .
after puncture of the right common femoral vein , a 9-fr sheath was inserted . left brachiocephalic venography demonstrated obstruction of the svc and confluence ( fig .
the pressure gradient between the left brachiocephalic vein and distal svc was 24 mm hg .
predilatation using a 10-mm - diameter balloon catheter ( boston scientific , galway , ireland ) was performed to determine the stent size and allow for the easy navigation of the stenosis as well as placement of the stent .
venography revealed that the length of the lesion was approximately 3 cm and the diameter of the svc was approximately 12 mm .
to prevent proximal and distal tumor overgrowth , a 14 mm  8 cm stent - graft was introduced over a 0.035-inch , 180-cm - long extra stiff amplatz guide - wire ( cook , bloomington , in , usa ) , which was deployed successfully across the stenosis ( fig .
post - stenting balloon dilation of the stent was then performed using a 10 mm  4 cm balloon catheter .
venography immediately after stent placement confirmed the correct positioning of the stent and the pressure gradient decreased to 6 mm hg .
the patient died at home 14 months after stent placement . at the time of death
, the patient showed no recurrent symptoms of svcs , suggesting continued patency of the stent . a 77-year - old man presented with cough , whitish sputum , and dyspnea .
a chest radiograph showed an ill - defined mass in the right upper lung field .
histology confirmed the diagnosis of squamous cell carcinoma and the patient underwent four cycles of chemotherapy for three months .
the patient then presented with swelling of the face and severe dyspnea for 10 days .
subsequent ct demonstrated progression of the mass and obstruction of the svc caused by the mass and mediastinal lymphadenopathy ( fig .
right internal jugular venography via the right common femoral vein demonstrated obstruction of the svc with venous collateral development ( fig .
the pressure gradient between the right internal jugular vein and distal svc was 21 mm hg .
venography revealed that the length of the lesion was approximately 4.5 cm and the diameter of the svc was approximately 11 mm . a 14 mm  8 cm stent - graft ( fig .
2c ) was successfully inserted . to prevent brachiocephalic vein occlusion by the stent - graft ,
venography immediately after stent placement confirmed the correct positioning of the stent and the pressure gradient decreased to 7 mm hg . clinical symptoms improved immediately after stent placement and did not receive any prophylactic anticoagulation .
the patient died at home seven months after stent placement . at the time of death
, the patient showed no recurrent symptoms of svcs , suggesting continued patency of the stent .
a chest radiograph showed an ill - defined mass in the right upper lung field . computed tomography ( ct ) revealed an ill - defined infiltrating central mass with mediastinal lymphadenopathy .
histology confirmed the diagnosis of squamous cell carcinoma and consequently , the patient underwent four cycles of chemotherapy for two months .
the patient then presented with swelling of the face and severe dyspnea for a week .
subsequent ct demonstrated progression of the mass , obstruction of the svc , confluence of both brachiocephalic veins ( fig .
although thrombolysis of the right brachiocephalic thrombosis and subsequent bilateral stenting could be performed , there was a risk of complications following thrombolysis because of the patient 's advanced age .
we thus decided on the unilateral placement of a triple - layered stent - graft ( vascular comvi stent - graft , taewoong medical , gimpo , korea ) that was 5 mm long at both bare extensions ( fig .
the triple - layered stent - graft was composed of two uncovered nitinol self - expanding metallic stents and an expanded polytetrafluoroethylene ( eptfe ) membrane between two uncovered stent layers .
after puncture of the right common femoral vein , a 9-fr sheath was inserted . left brachiocephalic venography demonstrated obstruction of the svc and confluence ( fig .
the pressure gradient between the left brachiocephalic vein and distal svc was 24 mm hg .
predilatation using a 10-mm - diameter balloon catheter ( boston scientific , galway , ireland ) was performed to determine the stent size and allow for the easy navigation of the stenosis as well as placement of the stent .
venography revealed that the length of the lesion was approximately 3 cm and the diameter of the svc was approximately 12 mm .
to prevent proximal and distal tumor overgrowth , a 14 mm  8 cm stent - graft was introduced over a 0.035-inch , 180-cm - long extra stiff amplatz guide - wire ( cook , bloomington , in , usa ) , which was deployed successfully across the stenosis ( fig .
post - stenting balloon dilation of the stent was then performed using a 10 mm  4 cm balloon catheter .
venography immediately after stent placement confirmed the correct positioning of the stent and the pressure gradient decreased to 6 mm hg .
the patient died at home 14 months after stent placement . at the time of death
, the patient showed no recurrent symptoms of svcs , suggesting continued patency of the stent .
a chest radiograph showed an ill - defined mass in the right upper lung field .
histology confirmed the diagnosis of squamous cell carcinoma and the patient underwent four cycles of chemotherapy for three months .
the patient then presented with swelling of the face and severe dyspnea for 10 days .
subsequent ct demonstrated progression of the mass and obstruction of the svc caused by the mass and mediastinal lymphadenopathy ( fig .
right internal jugular venography via the right common femoral vein demonstrated obstruction of the svc with venous collateral development ( fig .
the pressure gradient between the right internal jugular vein and distal svc was 21 mm hg .
venography revealed that the length of the lesion was approximately 4.5 cm and the diameter of the svc was approximately 11 mm . a 14 mm  8 cm stent - graft ( fig .
2c ) was successfully inserted . to prevent brachiocephalic vein occlusion by the stent - graft ,
venography immediately after stent placement confirmed the correct positioning of the stent and the pressure gradient decreased to 7 mm hg . clinical symptoms improved immediately after stent placement and did not receive any prophylactic anticoagulation .
the patient died at home seven months after stent placement . at the time of death , the patient showed no recurrent symptoms of svcs , suggesting continued patency of the stent .
endovascular stenting may be used as a first - line therapeutic measure in patients with malignant svcs because stenting does not interfere with subsequent antitumor treatments and provides urgent relief of symptoms ( 6 , 8) .
additionally , endovascular stenting greatly improves the quality of life of patients , who usually have a short life expectancy ( 8) .
although many studies have reported the efficacy of endovascular stenting in patients with malignant svcs , recurrence following initial successful stenting still occurs in up to 18% of cases ( 10 ) , and is attributed to tumor ingrowth inside the stent or venous thrombosis .
however , most patients with malignant svcs have a short life expectancy and the stent remains patent until death .
furthermore , stent occlusion can be treated with thrombolysis , balloon dilation , or further stent insertion with good secondary patency rates . however , secondary endovascular treatments are sometimes difficult and have additional costs .
anticoagulation therapy is often prescribed for patients with malignant svcs after stenting , although its efficacy has not been clearly confirmed ( 8) . moreover , determining the status of optimum anticoagulant therapy is difficult ( 10 ) .
thus , to prevent stent occlusion and improve the patency rate of stents , we thought that it was important to prevent tumor ingrowth into the stents .
this had led to the study of stent - grafts that are effective in preventing tumor ingrowth and subsequent stent occlusion .
endovascular stent - graft placement has been used for emergency repair of the svc ( 13 , 14 ) . another case involved repair of recurrent svc obstruction that occurred immediately or three weeks after metallic stent placement ( 11 , 12 ) . to our knowledge , in contrast to previously reported cases , our cases are the first to include the primary placement of an eptfe - covered stent in patients with malignant svcs . prior to using a stent - graft
first , risk of stent migration exists : stent migration remains a significant long term complication and is occasionally fatal ( 15 ) .
stent migration occurred in neither of our cases because the partially covered stent with both bare extensions and outer bare stent design might have prevented stent migration .
generally , to avoid stent migration , the diameter of the stent should be 10 - 20% greater than that of the lesion ( 7 ) .
second , placing a long length graft at the confluence of the brachiocephalic veins carries the risk of occlusion of the contralateral branch .
however , when both brachiocephalic veins were invaded by the tumor , unilateral brachiocephalic vein revascularization was sufficient and provided higher flow through the graft than when both brachiocephalic veins were revascularized ( 16 ) .
nagata et al . ( 7 ) suggested that unilateral relief of obstruction may allow collateral flow from the contralateral vein via the cervical and intracranial route .
the case 1 patient , in whom the stent - graft was placed from the svc to the left brachiocephalic vein , experienced symptomatic relief .
follow - up ct images confirmed patency of the stent - graft and contralateral veins via collateral flow of the cervical route . in conclusion ,
the two study cases demonstrate the potential efficacy of stent - graft placement for the palliative treatment of malignant svcs .
however , further investigation is necessary because the patency of the stent - graft in the venous system remains to be determined .
we report successful outcomes after endovascular placement of a stent graft in a 74- and a 77-year - old men , both of whom had malignant superior vena cava syndrome caused by squamous cell carcinoma . in each patient , 
 successful palliation of the malignant superior vena cava syndrome was achieved by placement of a stent graft . 
 no procedure - related complications were observed . 
 the patients were asymptomatic until their deaths , seven and 14 months after stent graft placement , respectively .