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Radiology
Descending
thoracic aortic aneurysm in a case of pulmonary tuberculosis :treatment by
endovascular stentgraft placement
A 38-year-old lady presented with history of intermittent low-grade fever, hemoptysis and left axillary swelling of nine month's duration. Her chest radiograph revealed bilateral perihilar infiltration in both lung fields (Fig1). FNAC of the left axillary swelling confirmed tuberculous etiology. Subsequently, she was started on antituberculous therapy following which the hemoptysis resolved. She presented with massive hemoptysis five months after institution of antituberculous therapy. The chest radiograph repeated at this time showed a lobulated, soft tissue opacity in region of the left hilum (Fig.2). A CT scan of the chest showed a descending thoracic aorta aneurysm with a thrombosed component in close relation to the left bronchus (Fig.3). CT angiography revealed a saccular aneurysm of the descending thoracic aorta measuring 8x5x9.5cms arising from posterior wall, the neck of the aneurysm being 5 cms distal to the origin of the left subclavian artery (Fig.4). Digital substraction angiogram confirmed the morphology and location of the aneurysm (Fig.5, 6).
Antibiotic prophylaxis was started from the day prior to the planned procedure of stent-graft placement. Under local anesthesia, vascular access was achieved by surgical exposure of the common femoral artery after which a direct puncture of the artery was performed and an Amplatz extra stiff wire (0.035, 260 cms Cook) was introduced upto the aortic arch. The patient was anticoagulated with intravenous heparin (150 IU/Kg) . A custom designed Zenith thoracic endovascular stentgraft system (Dilator/sheath assembly 20F Cook) was introduced over the guide wire under fluoroscopic guidance after serial dilatations and lubrication with the sofratulle jelly to facilitate its passage. Prior to deployment, the arterial blood pressure was lowered to a mean of 60 mm of Hg using intravenous sodium nitroprusside to decrease inadvertent deployment of the graft downstream of the target site due to the force of aortic blood flow. The stentgraft was released in the correct position distal to the origin of left subclavian artery after repeated road mapping done with straight flush catheter (5F, Cook) through contralateral femoral access. Stent-plasty of the proximal anchoring segment was done with a compliant latex balloon for better anchor of the prosthesis to the aortic wall. Post-procedure aortogram revealed complete exclusion of the aneurysm with no endoleak (Fig.7). Following the procedure, the puncture site was sutured and the patient was transferred to the intensive care unit for observation.
The patient was discharged on fifth day with uneventful post procedure recovery. Follow up CT angiography done after one month revealed stent in situ and no end leak (Fig.8).
Discussion :
Endovascular treatment for acute as well as chronic cases of descending thoracic aortic diseases (Type B dissections, aneurysms) is becoming more and more popular as it respects tissue integrity and obviates major morbidity and mortality associated with traditional surgical therapy.
Aneurysms of the thoracic aorta are uncommon, but life threatening conditions. They are often asymptomatic, presenting as unsuspected masses on chest radiograph. Clinical manifestations are related to aneurysm expansion, with compression and erosion of adjacent structures, associated aortic dissection and rupture. Twenty five percent of patients with thoracic aortic aneurysm have additional aneurysms, usually of the abdominal aorta. Without intervention, 1&3-year survival rates of nondissecting thoracic aneurysms have been reported to be 58.2% and 25.5% respectively. Surgical repair with graft interposition has been the traditional therapy for patients with descending thoracic aortic aneurysm. Despite surgical advances, the reported operative mortality is still substantial and ranges between 5 and 20% in elective cases, increasing to nearly 50% in patients who need emergency operative treatment. Morbidity is also significant with paraplegia seen in 2 to 10%. Moreover, in several cases, surgery is contraindicated because of patient's old age and concomitance pathologies (chronic obstructive pulmonary disease, renal failure etc.) . Transluminal endovscular stentgrafting provides an attractive therapeutic alternative for these clinically challenging patients.
Preprocedure imaging and anatomic considerations in graft planning:
Patients with descending thoracic aortic aneurysm which are planned for endovascular stent graft need to undergo spiral computed tomography with three dimensional reconstruction and thoracic aortography using calibrated catheter. The main anatomic consideration that needs to be evaluated before the placement of endovascular graft is the presence of adequate proximal and distal length. The distance from the origin of the left subclavian artery to the proximal aspect of the aneurysm should be atleast 2 cms. This allows adequate anchoring of the device and ensures that the stent graft is not inadvertently placed over the origin of the artery. If the aneurysm is adjacent to the left subclavian artery, a more favourable neck may be created by transposing the left subclavian artery on to the left common carotid artery before commencing stentgraft procedure. The stent graft is usually oversized by 3 to 4mm so as to allow better radial fixing to the aortic wall. To limit exclusion of the intercostal arteries, the overall length of the stentgraft is kept to the minimum. The pelvic vasculature is also studied to evaluate the diameter and tortuosity of the vessel through which the stent graft will be delivered.
The potential complication associated with thoracic stent-grafts are paraplegia and endoleak - particularly in early and delayed stage.
The recommended follow up examination to be carried out at 30 days, 6 months, 12 months and annually thereafter includes complete blood count, plain x-ray (AP and lateral), spiral CT.
Endovascular treatment has its contraindication i.e. severe aortoiliac occlusive disease, extreme tortuosity of descending aorta, absence of proximal or distal landing zone consisting of atleast 1 cm of normal aorta necessary for safe graft deployment.
Endovascular stentgrafting posseses additional advantages of minimally invasive procedure, with decrease in associated hospital stay, less morbidity and mortality & a promising alternative to extensive surgery in clinically challenging patients.
Case 14 : Contributed
by Dr. Krantikumar Rathod
Other Cases
A 38-year-old lady presented with history of intermittent low-grade fever, hemoptysis and left axillary swelling of nine month's duration. Her chest radiograph revealed bilateral perihilar infiltration in both lung fields (Fig1). FNAC of the left axillary swelling confirmed tuberculous etiology. Subsequently, she was started on antituberculous therapy following which the hemoptysis resolved. She presented with massive hemoptysis five months after institution of antituberculous therapy. The chest radiograph repeated at this time showed a lobulated, soft tissue opacity in region of the left hilum (Fig.2). A CT scan of the chest showed a descending thoracic aorta aneurysm with a thrombosed component in close relation to the left bronchus (Fig.3). CT angiography revealed a saccular aneurysm of the descending thoracic aorta measuring 8x5x9.5cms arising from posterior wall, the neck of the aneurysm being 5 cms distal to the origin of the left subclavian artery (Fig.4). Digital substraction angiogram confirmed the morphology and location of the aneurysm (Fig.5, 6).
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Fig.1
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Fig.2
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Antibiotic prophylaxis was started from the day prior to the planned procedure of stent-graft placement. Under local anesthesia, vascular access was achieved by surgical exposure of the common femoral artery after which a direct puncture of the artery was performed and an Amplatz extra stiff wire (0.035, 260 cms Cook) was introduced upto the aortic arch. The patient was anticoagulated with intravenous heparin (150 IU/Kg) . A custom designed Zenith thoracic endovascular stentgraft system (Dilator/sheath assembly 20F Cook) was introduced over the guide wire under fluoroscopic guidance after serial dilatations and lubrication with the sofratulle jelly to facilitate its passage. Prior to deployment, the arterial blood pressure was lowered to a mean of 60 mm of Hg using intravenous sodium nitroprusside to decrease inadvertent deployment of the graft downstream of the target site due to the force of aortic blood flow. The stentgraft was released in the correct position distal to the origin of left subclavian artery after repeated road mapping done with straight flush catheter (5F, Cook) through contralateral femoral access. Stent-plasty of the proximal anchoring segment was done with a compliant latex balloon for better anchor of the prosthesis to the aortic wall. Post-procedure aortogram revealed complete exclusion of the aneurysm with no endoleak (Fig.7). Following the procedure, the puncture site was sutured and the patient was transferred to the intensive care unit for observation.
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The patient was discharged on fifth day with uneventful post procedure recovery. Follow up CT angiography done after one month revealed stent in situ and no end leak (Fig.8).
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Endovascular treatment for acute as well as chronic cases of descending thoracic aortic diseases (Type B dissections, aneurysms) is becoming more and more popular as it respects tissue integrity and obviates major morbidity and mortality associated with traditional surgical therapy.
Aneurysms of the thoracic aorta are uncommon, but life threatening conditions. They are often asymptomatic, presenting as unsuspected masses on chest radiograph. Clinical manifestations are related to aneurysm expansion, with compression and erosion of adjacent structures, associated aortic dissection and rupture. Twenty five percent of patients with thoracic aortic aneurysm have additional aneurysms, usually of the abdominal aorta. Without intervention, 1&3-year survival rates of nondissecting thoracic aneurysms have been reported to be 58.2% and 25.5% respectively. Surgical repair with graft interposition has been the traditional therapy for patients with descending thoracic aortic aneurysm. Despite surgical advances, the reported operative mortality is still substantial and ranges between 5 and 20% in elective cases, increasing to nearly 50% in patients who need emergency operative treatment. Morbidity is also significant with paraplegia seen in 2 to 10%. Moreover, in several cases, surgery is contraindicated because of patient's old age and concomitance pathologies (chronic obstructive pulmonary disease, renal failure etc.) . Transluminal endovscular stentgrafting provides an attractive therapeutic alternative for these clinically challenging patients.
Preprocedure imaging and anatomic considerations in graft planning:
Patients with descending thoracic aortic aneurysm which are planned for endovascular stent graft need to undergo spiral computed tomography with three dimensional reconstruction and thoracic aortography using calibrated catheter. The main anatomic consideration that needs to be evaluated before the placement of endovascular graft is the presence of adequate proximal and distal length. The distance from the origin of the left subclavian artery to the proximal aspect of the aneurysm should be atleast 2 cms. This allows adequate anchoring of the device and ensures that the stent graft is not inadvertently placed over the origin of the artery. If the aneurysm is adjacent to the left subclavian artery, a more favourable neck may be created by transposing the left subclavian artery on to the left common carotid artery before commencing stentgraft procedure. The stent graft is usually oversized by 3 to 4mm so as to allow better radial fixing to the aortic wall. To limit exclusion of the intercostal arteries, the overall length of the stentgraft is kept to the minimum. The pelvic vasculature is also studied to evaluate the diameter and tortuosity of the vessel through which the stent graft will be delivered.
The potential complication associated with thoracic stent-grafts are paraplegia and endoleak - particularly in early and delayed stage.
The recommended follow up examination to be carried out at 30 days, 6 months, 12 months and annually thereafter includes complete blood count, plain x-ray (AP and lateral), spiral CT.
Endovascular treatment has its contraindication i.e. severe aortoiliac occlusive disease, extreme tortuosity of descending aorta, absence of proximal or distal landing zone consisting of atleast 1 cm of normal aorta necessary for safe graft deployment.
Endovascular stentgrafting posseses additional advantages of minimally invasive procedure, with decrease in associated hospital stay, less morbidity and mortality & a promising alternative to extensive surgery in clinically challenging patients.