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Department of Radiology
Seth G.S. Medical College and K.E.M. Hospital, Mumbai , India
Interventional Case Record
Interventional Case Record
Embolisation of a Complex Iatrogenic Iliac Arteriovenous Fistula (AVF)
Embolisation of a Complex Iatrogenic Iliac Arteriovenous Fistula (AVF)
Contributed by : Nikhil Parvatkar
Contributed by : Nikhil Parvatkar
Introduction:
Introduction:
An arteriovenous fistula (AVF) is an abnormal communication between an artery and a vein. It is frequently a consequence of trauma or iatrogenic injury. Iliac AVF can be seen after lumbar spinal surgery. It may present to an emergency department with symptoms of deep venous thrombosis or heart failure. History and physical examination findings can suggest AVF but the diagnosis is often based on imaging studies such as Doppler ultrasonography (US), CT or MR angiography. Although surgery is usually preferred as the first choice of treatment in this disorder endovascular approach has been more commonly used due to recent advances in stent technology. (1)
An arteriovenous fistula (AVF) is an abnormal communication between an artery and a vein. It is frequently a consequence of trauma or iatrogenic injury. Iliac AVF can be seen after lumbar spinal surgery. It may present to an emergency department with symptoms of deep venous thrombosis or heart failure. History and physical examination findings can suggest AVF but the diagnosis is often based on imaging studies such as Doppler ultrasonography (US), CT or MR angiography. Although surgery is usually preferred as the first choice of treatment in this disorder endovascular approach has been more commonly used due to recent advances in stent technology. (1)
Here we present a case of a young woman who had undergone a L5-S1 discectomy , 3 years back, and was diagnosed with a complex right iliac arteriovenous fistula which was likely iatrogenic, and we managed it endovascularly with various challenges and techniques as will be described.
Here we present a case of a young woman who had undergone a L5-S1 discectomy , 3 years back, and was diagnosed with a complex right iliac arteriovenous fistula which was likely iatrogenic, and we managed it endovascularly with various challenges and techniques as will be described.
Clinical profile:
Clinical profile:
A 34-year-old woman with a history of discectomy for an L5-S1 prolapsed intervertebral disc in May 2023 presented with a three-month history of pain and swelling in the right lower limb and poor effort tolerance. The pain was intermittent and aggravated by activity.
A 34-year-old woman with a history of discectomy for an L5-S1 prolapsed intervertebral disc in May 2023 presented with a three-month history of pain and swelling in the right lower limb and poor effort tolerance. The pain was intermittent and aggravated by activity.
Following her spinal surgery, the patient remained bedridden for approximately five days and was minimally mobile for one month. She subsequently developed right lower limb swelling and was diagnosed with extensive DVT of the right leg. This was managed medically with Tab. Rivaroxaban (20 mg), and her symptoms improved. During the current admission, a Doppler examination of the lower limb showed no evidence of DVT. However, a 2D echocardiogram revealed an ejection fraction (EF) of 60%, severe tricuspid regurgitation (TR), and moderate pulmonary hypertension (PH).
Following her spinal surgery, the patient remained bedridden for approximately five days and was minimally mobile for one month. She subsequently developed right lower limb swelling and was diagnosed with extensive DVT of the right leg. This was managed medically with Tab. Rivaroxaban (20 mg), and her symptoms improved. During the current admission, a Doppler examination of the lower limb showed no evidence of DVT. However, a 2D echocardiogram revealed an ejection fraction (EF) of 60%, severe tricuspid regurgitation (TR), and moderate pulmonary hypertension (PH).
Radiological findings :
Radiological findings :
CT Angiography showed a complex direct fistula between the right internal iliac artery and the right common iliac vein, with aneurysmal dilatation of the fistula. (FIG 1,2,3). There was dilatation of the IVC and pelvic veins. (Fig 4)
CT Angiography showed a complex direct fistula between the right internal iliac artery and the right common iliac vein, with aneurysmal dilatation of the fistula. (FIG 1,2,3). There was dilatation of the IVC and pelvic veins. (Fig 4)
Fig. 1
Fig. 2
Fig. 3
Fig. 4
FIG 1,2 and 3 – Reformatted CT angiography images showing a complex right iliac arteriovenous fistula between the right internal iliac artery and right common iliac vein with aneurysmal dilatation of the fistula.
FIG 4 : Dilated IVC due to the increased inflow from the fistula.
Catheter angiogram was performed to evaluate the fistula in detail and plan management.
Catheter angiogram was performed to evaluate the fistula in detail and plan management.
An aortogram performed via via right right CFA access, demonstrated the direct fistula between the right common iliac artery and right common iliac vein with opacification of the IVC. (Fig 5, Fig 6) The distal branches of the right internal iliac artery were not seen due to the steal through the fistula. The right external iliac artery was normal. There were arterial feeders to the fistula from the left internal iliac artery and a few right lumbar arteries as well.
An aortogram performed via via right right CFA access, demonstrated the direct fistula between the right common iliac artery and right common iliac vein with opacification of the IVC. (Fig 5, Fig 6) The distal branches of the right internal iliac artery were not seen due to the steal through the fistula. The right external iliac artery was normal. There were arterial feeders to the fistula from the left internal iliac artery and a few right lumbar arteries as well.
Fig. 5
Fig. 6
FIG 5 : Angiogram showing the direct fistula between the right common iliac artery and right common iliac vein with opacification of the IVC. THe right external iliac artery was normal.
FIG 6 : Selective angiogram from the fistula and from the right Common iliac vein.
Interventional technique :
Interventional technique :
The right common femoral vein was accessed with a 12 Fr sheath. A CODA balloon was inflated at the venous end in the common iliac vein just across the fistula to occlude the venous end, An angiogram was performed from the right internal iliac artery to demonstrate the fistula and the distal branches of the internal iliac artery. (FIG 7)
The right common femoral vein was accessed with a 12 Fr sheath. A CODA balloon was inflated at the venous end in the common iliac vein just across the fistula to occlude the venous end, An angiogram was performed from the right internal iliac artery to demonstrate the fistula and the distal branches of the internal iliac artery. (FIG 7)
Selective catheterization of the anterior and posterior divisions of the right internal iliac artery was achieved and we embolised them using long pushable coils. (FIG 8). The rationale of this was to avoid retrograde filling of the fistula from these branches after embolisation.
Selective catheterization of the anterior and posterior divisions of the right internal iliac artery was achieved and we embolised them using long pushable coils. (FIG 8). The rationale of this was to avoid retrograde filling of the fistula from these branches after embolisation.
Fig. 7
Fig. 8
FIG 7 : Angiogram after balloon occlusion from the venous end, demonstrating the distal internal iliac branches.
FIG 8 : Coil embolisation of the distal internal iliac artery branches
Once these were embolised , we planned to occlude the fistula using a Amplatzer Type II vascular plug. However entry into the fistula and crossover from the left side were challenges to place the plug from the arterial end. Thus we navigated into the fistula from the arterial end and snared the wire across the fistula from the right common femoral vein and placed a long 10 Fr sheath across the fistula. (FIG 9). We deployed a 14 mm plug in the right internal iliac artery proximal to the fistula. (Video 1). Meanwhile we did not lose access to the distal internal iliac artery to embolise any residual arterial feeders. The fistula still showed some residual flow through it. (Video 2)
Once these were embolised , we planned to occlude the fistula using a Amplatzer Type II vascular plug. However entry into the fistula and crossover from the left side were challenges to place the plug from the arterial end. Thus we navigated into the fistula from the arterial end and snared the wire across the fistula from the right common femoral vein and placed a long 10 Fr sheath across the fistula. (FIG 9). We deployed a 14 mm plug in the right internal iliac artery proximal to the fistula. (Video 1). Meanwhile we did not lose access to the distal internal iliac artery to embolise any residual arterial feeders. The fistula still showed some residual flow through it. (Video 2)
Fig.9
video 1.mp4Video 1
VIDEO 2.mp4Video 2
FIG 9, Long sheath access into the right internal iliac artery from the venous end after snaring the wire from the arterial end.
Video 1 : Plug being deployed in the internal iliac artery.
Video 2 : Angiogram after plug deployment showing residual flow across the fistula.
However, the patient developed pulmonary edema (FIG 10) after this long session due to fluid overload. Therefore, we stopped the procedure and planned a second session.
However, the patient developed pulmonary edema (FIG 10) after this long session due to fluid overload. Therefore, we stopped the procedure and planned a second session.
FIG 10 : Chest radiograph showing changes of pulmonary edema.
In the second session, two days later, we catheterised the contralateral internal iliac arteries (left internal iliac artery) via right CFA access (Fig 11) and selectively cannulated the arterial feeders to the fistula and embolised them using coils and 25 % glue. (FIG 12). However the fistula still showed residual flow.
In the second session, two days later, we catheterised the contralateral internal iliac arteries (left internal iliac artery) via right CFA access (Fig 11) and selectively cannulated the arterial feeders to the fistula and embolised them using coils and 25 % glue. (FIG 12). However the fistula still showed residual flow.
FIG 11 : Left internal iliac artery angiogram showing arterial feeders into the fistula.
FIG 12 : Glue embolsiation of the contralateral feeders.
Thus we decided a third session (2 days later) in which we planned to perform balloon assisted glue embolization of the fistula. After accessing the right CFV with 12 FR shearth we inflated a CODA balloon across the fistula on the venous end. Due to the plug in the internal iliac artery, we had no access into the fistula from the arterial end. Thus a right IJV access was used to enter the fistula from the venous end using a MPA catheter. (FIG 13)
Thus we decided a third session (2 days later) in which we planned to perform balloon assisted glue embolization of the fistula. After accessing the right CFV with 12 FR shearth we inflated a CODA balloon across the fistula on the venous end. Due to the plug in the internal iliac artery, we had no access into the fistula from the arterial end. Thus a right IJV access was used to enter the fistula from the venous end using a MPA catheter. (FIG 13)
FIG 13 : Access into the distal branches from the jugular route through the fistula.
We cannulated and emboilised the residual feeders from posterior division of internal iliac artery using pushable coils. Once we made sure that all the distal branches were embolised, we embolised the fistula using 50 % glue, with continuous balloon occlusion on the venous end to prevent glue cast migration. (FIG 14,15, video 3).
We cannulated and emboilised the residual feeders from posterior division of internal iliac artery using pushable coils. Once we made sure that all the distal branches were embolised, we embolised the fistula using 50 % glue, with continuous balloon occlusion on the venous end to prevent glue cast migration. (FIG 14,15, video 3).
Fig. 14
Fig. 15
VIDEO 3.mp4Video 3
FIG 14 and 15 : Glue embolisation of the fistula with balloon occlusion of the venous end.
Video 3 : Glue embolisation of the fistula with balloon occlusion at the venous end.
After glue embolization we gradually deflated the balloon while simultaneously checking wether there was any movement in the glue cast. Final check angiogram showed complete successful embolisation of the fistula with no residual flow across. (FIG 16 , VIDEO 4).
After glue embolization we gradually deflated the balloon while simultaneously checking wether there was any movement in the glue cast. Final check angiogram showed complete successful embolisation of the fistula with no residual flow across. (FIG 16 , VIDEO 4).
Fig. 16
video 4.mp4Video 4
FIG 16 : video 4 Final Angiogram – No residual flow into the fistula, with complete embolisation.
Discussion
Discussion
Since first described by Linton and White in 1945, (2) arteriovenous fistulas (AVFs) secondary to lumbar spinal surgery have been rarely encountered. Vascular injury in lumbar spinal surgery occurs when surgical instruments penetrate beyond the anterior longitudinal ligament. (3) These complications typically occur at the L4-L5 and L5-S1 levels because the aortic and caval bifurcations lie immediately anterior to the L4-L5 disc space. The injury commonly involves the aorta, inferior vena cava (IVC), and iliac vessels due to their proximity to the intervertebral disc space and their relative immobility. Vessel injury is associated with both the level of surgery and the angle of instrumentation. The right common iliac artery and vein are the most frequently injured vessels due to their proximity to the L4-L5 level, where lumbar disc surgery is most often performed. (4) One study reported AVF as the most frequent vascular complication after lumbar disc surgery, accounting for 78 of 122 cases. (5)
Since first described by Linton and White in 1945, (2) arteriovenous fistulas (AVFs) secondary to lumbar spinal surgery have been rarely encountered. Vascular injury in lumbar spinal surgery occurs when surgical instruments penetrate beyond the anterior longitudinal ligament. (3) These complications typically occur at the L4-L5 and L5-S1 levels because the aortic and caval bifurcations lie immediately anterior to the L4-L5 disc space. The injury commonly involves the aorta, inferior vena cava (IVC), and iliac vessels due to their proximity to the intervertebral disc space and their relative immobility. Vessel injury is associated with both the level of surgery and the angle of instrumentation. The right common iliac artery and vein are the most frequently injured vessels due to their proximity to the L4-L5 level, where lumbar disc surgery is most often performed. (4) One study reported AVF as the most frequent vascular complication after lumbar disc surgery, accounting for 78 of 122 cases. (5)
Lower limb swelling and varices in these patients often mimic acute or chronic deep vein thrombosis (DVT) in younger populations, while older patients more frequently experience swelling secondary to congestive heart failure.
Lower limb swelling and varices in these patients often mimic acute or chronic deep vein thrombosis (DVT) in younger populations, while older patients more frequently experience swelling secondary to congestive heart failure.
Angiography remains the gold standard for diagnosing AVF; however, contrast-enhanced CT and MR angiography are effective noninvasive alternatives for depicting vascular injury and fistulas. Early filling of the venous system on contrast-enhanced CT or MRI is helpful for both diagnosis and treatment planning, as it reveals the fistula's localization, vessel diameters, and distance from the aortic bifurcation.
Angiography remains the gold standard for diagnosing AVF; however, contrast-enhanced CT and MR angiography are effective noninvasive alternatives for depicting vascular injury and fistulas. Early filling of the venous system on contrast-enhanced CT or MRI is helpful for both diagnosis and treatment planning, as it reveals the fistula's localization, vessel diameters, and distance from the aortic bifurcation.
Surgical treatment of iliac AVFs carries high mortality and morbidity rates due to dilated collaterals and the deep location of the iliac vessels. Consequently, minimally invasive endovascular techniques are now the preferred option, offering lower complication rates and a shorter, less painful recovery period. Generally, traditional open surgical repairs involve greater trauma, increased bleeding, and prolonged operative duration compared to endovascular repairs. While the patient in our study did not experience procedure-related morbidity or mortality, reported operative mortality rates for open repair range from 5% to 10%.
Surgical treatment of iliac AVFs carries high mortality and morbidity rates due to dilated collaterals and the deep location of the iliac vessels. Consequently, minimally invasive endovascular techniques are now the preferred option, offering lower complication rates and a shorter, less painful recovery period. Generally, traditional open surgical repairs involve greater trauma, increased bleeding, and prolonged operative duration compared to endovascular repairs. While the patient in our study did not experience procedure-related morbidity or mortality, reported operative mortality rates for open repair range from 5% to 10%.
As a result, more surgeons and patients are opting for endovascular methods. Since Zajko et al. first successfully treated a common iliac artery-to-inferior vena cava fistula in 1995, endovascular repair has been widely used for IAVF following lumbar disc surgery. (6) Various strategies, including stent grafts, coiling, plug embolization, and balloon-assisted glue embolization, have been documented. In our case, due to the complexity and multiple feeders caused by the chronicity of the fistula, multiple access points and strategies were required to achieve complete embolization.
As a result, more surgeons and patients are opting for endovascular methods. Since Zajko et al. first successfully treated a common iliac artery-to-inferior vena cava fistula in 1995, endovascular repair has been widely used for IAVF following lumbar disc surgery. (6) Various strategies, including stent grafts, coiling, plug embolization, and balloon-assisted glue embolization, have been documented. In our case, due to the complexity and multiple feeders caused by the chronicity of the fistula, multiple access points and strategies were required to achieve complete embolization.
In conclusion, iliac AVFs resulting from lumbar spinal surgery may involve multiple vessels. Diagnosis can be difficult if not suspected, as presenting symptoms are often nonspecific. A history of lumbar, pelvic, or inguinal surgery combined with the presence of a murmur over the groin vessels should raise clinical suspicion. Endovascular treatment remains a safe and appropriate method for managing iliac AVFs.
In conclusion, iliac AVFs resulting from lumbar spinal surgery may involve multiple vessels. Diagnosis can be difficult if not suspected, as presenting symptoms are often nonspecific. A history of lumbar, pelvic, or inguinal surgery combined with the presence of a murmur over the groin vessels should raise clinical suspicion. Endovascular treatment remains a safe and appropriate method for managing iliac AVFs.
References
References
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