Case Report
Percutaneous Embolization of a Postnephrectomy Arteriovenous Fistula With Intervening Pseudoaneurysm Using the Amplatzer Vascular Plug 2
Vascular and Endovascular Surgery 2014, Vol. 48(7-8) 516-521 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1538574414561230 ves.sagepub.com
Ahmed Kamel Abdel-Aal, MD, MSc, PhD1, Ahmed Elsabbagh, MD1, Hesham Soliman, MD1, Maysoon Hamed, MD2, Edgar Underwood, MD1, and Souheil Saddekni, MD, FSIR, FAHA1
Abstract Although renal arteriovenous fistula (AVF) is an uncommon condition, it may lead to high cardiac output heart failure and renal insufficiency. Recently, percutaneous transcatheter embolization has replaced traditional surgery as the first line of treatment. We report a case of a 68-year-old male who presented with a renal AVF and was treated by percutaneous transcatheter embolization using the Amplatzer Vascular Plug 2 (AVP 2; St Jude Medical, Plymouth, Minnesota) through an arterial access. To our knowledge, the use of AVP 2 device in the treatment of renal AVF as a single embolotherapy device through the transarterial route has not been previously reported in the literature. Our technique demonstrates the feasibility and safety of AVP 2 device in the treatment of renal AVF. Keywords renal arteriovenous fistula, postnephrectomy, pseudoaneurysm, transcatheter embolization, Amplatzer Vascular Plug 2, coil embolization, percutaneous, embolotherapy, endovascular
Introduction
Case Report
Renal arteriovenous fistula (AVF), which is an abnormal connection between the renal artery and the vein, is a very rare condition. They are classified according to the etiology into congenital, idiopathic, or acquired types. Congenital and idiopathic types constitute less than 30% of all renal AVFs. Acquired renal AVFs maybe secondary to trauma, carcinoma, arteritis, or iatrogenic.1,2 Postnephrectomy renal AVF is a rare complication of an otherwise frequently performed procedure. Treatment of renal AVF has traditionally been surgical in the form of total or partial nephrectomy with ligation of the feeding vessel.3 Endovascular treatment, through percutaneous transcatheter embolization, has gradually replaced open surgery as the first-line therapy of renal AVFs. However, percutaneous embolization has a considerable risk of migration of the embolic materials to the venous and pulmonary circulations. Recently, the use of the Amplatzer Vascular Plug 2 (AVP 2) was described in embolization of renal AVFs in several vascular territories, more specifically in high-flow renal AVFs.4 Several authors reported the AVP 2 device to be effective and safe in treatment of renal AVFs, with decreased risk of device migration compared to other embolic material.4,5
We present a 68-year-old male patient with history of renal cell carcinoma who was treated by partial nephrectomy. The patient also had abdominal aortic aneurysm (AAA) which was treated by endovascular aortic stent graft and presented to our institution for computed tomography angiogram (CTA) of the abdomen and pelvis as part of a routine follow-up. The CTA demonstrated that the aortic stent graft was patent. However, there was contrast opacification of the renal vein during the arterial phase suggesting renal AVF, with a large Pseudoaneurysm (PSA) connecting the renal artery and renal vein at the site of left partial nephrectomy (Figure 1). The clinical team was concerned about the potential rupture of the large PSA, and due to the patient’s associated
1 Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA 2 Department of Family Medicine, University of Alabama, Tuscaloosa, AL, USA
Corresponding Author: Ahmed Kamel Abdel-Aal, Department of Radiology, University of Alabama at Birmingham, 619 19th street south, Birmingham, AL 35249, USA. Email: [email protected]
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Figure 1. A 68-year-old male patient with history of renal cell carcinoma treated by partial nephrectomy. A, Axial computed tomography (CT) angiogram image showing contrast opacification of the renal vein (arrowheads) during the arterial phase suggesting renal arteriovenous fistula, with a large pseudoaneurysm (large arrow) connecting the upper pole renal artery branch (small arrow) and renal vein at the site of left partial nephrectomy. B, Coronal CT angiogram image showing the arterial feeder (curved arrow) and the large pseudoaneurysm (asterisk).
Figure 2. Aortogram showing a large pseudoaneurysm (asterisk) involving the upper pole of the left kidney with early opacification of the renal vein (small arrow).
comorbidities, an interdisciplinary consensus opted to offer the patient a minimally invasive treatment. Therefore, the patient was referred to our Interventional Department for percutaneous transcatheter embolotherapy of the renal AVF and the associated large PSA. The patient was brought to our angiosuite, and right common femoral artery access was obtained. The initial aortogram showed a large PSA involving the upper pole of the left kidney with early opacification of the renal vein, consistent with a renal AVF (Figure 2). The right renal artery was then catheterized using 5F catheter (RC2; Cook, Bloomington, Indiana) and angiogram was performed, which showed a large PSA fed by one of the upper pole branches of the renal artery and draining directly into the renal vein (Figure 3). A 2.8F microcatheter
(Miraflex; Merit, South Jordan, Utah) was then advanced into the PSA, and 3 variable-sized detachable hydrogel coils (Azur; Terumo, Tokyo, Japan) were deployed into the PSA (Figure 4). During deployment, the third coil migrated through the renal vein to a left inferior pulmonary artery branch. The migrated coil was retrieved using a snare (Goose neck snare; Covidien, Plymouth, Minnesota) through a right femoral vein approach (Figure 5). The renal AVF remained patent. In order to prevent further coil migration, an occlusion balloon catheter (Fogarty; Edwards Lifesciences, Irvine, California) was inflated in the renal vein close to the PSA to occlude the renal AVF outflow (Figure 6). Several hydrogel coils were then deployed as mentioned earlier. Thrombosis of the PSA was then augmented by slowly injecting 300 units of thrombin into the PSA. The occlusion balloon was deflated and follow-up angiogram showed absent flow in the PSA, denoting occlusion of the renal AVF. The procedure was terminated, and the patient was discharged home after an uneventful 24 hours of observation. A routine follow-up CTA performed 2 months after the procedure to evaluate the aortic stent graft showed interval recanalization of the renal AVF, with several metal artifacts related to preexisting coils in PSA (Figure 7). Therefore, the patient was referred to our service again for further evaluation and treatment. The right common femoral artery was accessed and a 6F sheath (Flexor Ansel sheath; Cook, Bloomington, Indiana) was placed at the origin of the left renal artery. A 6F guiding catheter (Launcher; Medtronic, Minneapolis, Minnesota) was then advanced into the upper pole branch that feeds the renal AVF, and angiogram was performed and demonstrated preexisting coils residing in the PSA, with recanalization of the renal AVF (Figure 8A). At this point, a 6-mm AVP 2 was placed at the junction of the feeding artery and the PSA (Figure 8B). Position was then confirmed by angiogram, and the device was deployed. Follow-up angiogram performed from the main renal artery showed occlusion of the feeding artery with absent filling of the PSA denoting successful embolization (Figure 8C).
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Figure 3. A, Left renal angiogram showing a large pseudoaneurysm (asterisk) fed by one of the upper pole branches of the renal artery (curved arrow) and (B) draining directly into the renal vein (arrowheads).
Figure 4. Multiple variable-sized detachable hydrogel coils deployed in the pseudoaneurysm (arrowheads), using a 2.8F microcatheter (small arrow).
The patient had an unremarkable recovery and was discharged home in a stable condition. Follow-up CTAs done 4 and 10 months after the procedure and showed AVP 2 device residing in the left renal artery branch feeder without artifacts. There was no evidence of recanalization of the renal AVF (Figure 9).
Discussion The first renal AVF was reported by Vorela in 1928.1,6,7 The prevalence of renal AVF is less than 0.04%.6 Renal AVFs are classified according to their etiology into congenital, idiopathic, and acquired types. Congenital renal AVF arise from errors in vascular morphology and represent 14% to 27% of cases. Acquired renal AVF represents the majority of cases constituting about 70% to 80% of cases. Acquired renal AVF may result from trauma, malignancy, inflammation, or may be iatrogenic as in case of prior surgery.2,6,8,9 Congenital renal AVF consists of multiple communicating channels, while the acquired renal AVFs are characterized by having a single communicating channel between a single feeding artery and single draining vein.4 Postnephrectomy renal
Figure 5. Left pulmonary angiogram showing a migrated detachable hydrogel coil lodged in the left inferior pulmonary artery branch (arrowheads).
AVF occurs following partial nephrectomy for infectious or neoplastic etiology and is usually accompanied by PSA.3 The reported incidence of renal AVF and PSA after open partial nephrectomy is less than 0.5%.9 Our case represents an acquired renal AVF following open upper pole partial nephrectomy for renal cell carcinoma. The detailed pathophysiology of acquired renal AVF is not completely understood. The blunt-ended ligated renal artery subsequent to partial nephrectomy may distort the shear stress to the wall of the renal artery which seems to predispose to the formation of aneurysms. The contact of the pulsatile aneurysm to the adjacent vein may cause erosion of the venous vessel wall, which subsequently develops a communication and the formation of a renal AVF.6,8
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Figure 6. Inflated occlusion balloon catheter (small arrow) was placed in the left renal vein through a transfemoral vein route to prevent further coil migration from the pseudoaneurysm (large arrow).
Figure 7. Axial image from a routine follow-up computed tomography (CT) angiogram performed 2 months after the procedure to evaluate the aortic stent graft shows interval recanalization of the renal arteriovenous fistula, with contrast opacification of the left renal vein (curved arrow) during the arterial phase. Metal artifacts are related to preexisting coils in pseudoaneurysm (large arrow).
The presentation and diagnosis of renal AVF are occasionally achieved late, with some cases reported up to 40 years following nephrectomy (mean 14.5 years).2,8 Common manifestations of the renal AVF are abdominal bruit (90%-100% of cases), hypertension and cardiomegaly (60%-80% of cases), congestive heart failure (30%-40% of cases), gross hematuria (40% of cases), and pain (20% of cases).3,6,7,8 Although most patients present with one or more of the above-mentioned symptoms and signs, there are sporadic reports of incidental diagnosis of renal AVF.10 In our asymptomatic patient, the renal AVF was incidentally diagnosed during a CTA performed as part of routine follow-up for the patient’s AAA, which was previously treated by endovascular aortic stent graft. Computed tomograhy (CT) is considered more accurate than ultrasound in the detection and the demonstration
of the exact angioarchitecture of renal AVF. However, the gold standard technique for imaging remains catheter angiography. The latter enables diagnosis with ability to intervene in the same session.2,3,8,10,11 The indication for treatment of postnephrectomy renal AVFs includes progressive increase in size, impending rupture, recurrent or persistent hematuria, hypertension, pain, and, above all, when there is a risk of heart failure.2,3,5,10 In our case, the indication for treatment was the large PSA with concern for potential rupture. Endovascular transcatheter embolization is considered the first-line therapy because it has a high success rate and shorter hospital stay, combined with lower morbidity and mortality compared to surgery, which is more invasive and confers the risk of intraoperative anesthesia.5,9 Transcatheter embolization of renal AVF was first described by Bookstein and Goldstein in 1973,12 and numerous techniques and embolization materials have been reported since, including metallic coils, sclerozing liquid agents, and particulate embolization material.13 Paradoxical embolization, which is a potentially serious complication, limited the use of the last 2 agents.14 In our case, we started the embolization process using coils but due to paradoxical embolization of one of the coils to the lung, we decided to use the AVP 2 device. In the authors’ opinion, coils should only be used when secure placement is guaranteed, which can be achieved using balloon occlusion from the arterial or venous side to help reduce the flow. Alternatively, AVP 2 should be used which offers a more accurate and stable placement through a detachable system. The AVP 2 is a self-expanding, cylindrical occluding device made out of nitinol mesh wires. The device is secured at both ends with platinum marker bands. A stainless steel microscrew is welded to one of the platinum marker bands, which allows attachment to the 135-cm long delivery cable. The diameter of the AVP 2 ranges from 3 to 22 mm. It can be safely used in high-flow, short-vascular segments, such as renal AVF, where coils are less accurately and safely released. After placement of the device, angiograms can be performed to confirm location, and the device can then be deployed from the pusher wire in a relatively precise, controllable, intentional fashion by rotating the pusher wire. The device can be retrieved and repositioned, if the location is unsatisfactory, thus minimizing the risk of migration. Additionally, the device is usually oversized by 30% to 50% of the size of the target vessel which offers more stability in the deployed vessel, with less chances of migration. Additionally, the AVP 2 is better than detachable coils because only one device is needed to occlude the renal AVF.8,15 Several authors recommended AVP 2 as the first choice for occlusion of a renal AVF with high-flow and short-vascular connection, where the occlusion has to be in an exact location.15 Others document the cost-effectiveness of using this device compared to coils.5 The AVP 2 also has a distinctive appearance on computed tomography, with significantly less metal artifact compared to coils (Figure 9), allowing more accurate interpretation of follow-up studies.11 However, the AVP 2 device is usually delivered through a sheath or guiding
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Figure 8. A, Left renal angiogram showing the feeding arterial branch supplying the pseudoaneurysm (small arrow). Preexisting coils (large arrow) are seen residing in the contrast filled pseudoaneurysm (curved arrow), suggesting recanalization of the renal arteriovenous fistula. B, A nonsubtracted image showing the Amplatzer vascular plug 2 (curved arrow) placed at the junction of the feeding artery and the pseudoaneurysm. C, Follow-up angiogram performed from the main renal artery shows occlusion of the feeding artery (large arrow) by the Amplatzer vascular plug 2 with absent filling of the pseudoaneurysm denoting successful embolization.
relatively stiff compared to that of detachable coils, which might pose difficulty in advancing the device in tortuous anatomy.
Conclusion Our case demonstrates the feasibility of the use of AVP 2 in the treatment of renal AVF through embolization of the arterial feeder, especially in high-flow fistulas with short communication. In our case, the device offered several advantages over coils and appeared to be more cost effective.
Figure 9. Axial image of a computed tomography (CT) angiogram showing Amplatzer vascular plug 2 (small arrow) residing in the left renal artery branch feeder with minimal artifacts. There is absent contrast opacification of the left renal vein (large arrow) during the arterial phase, with no evidence of recanalization of the renal arteriovenous fistula.
catheter which might be difficult to place through stenotic renal arteries or distally in the renal vasculature where most of these fistulas are encountered. Furthermore, the delivery cable is
Declaration of Conflicting Interests The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Ahmed K. Abdel-Aal was consultant at St Jude Medical, Baxter Heathcare Coorporation, and Bard Peripheral Vascular, Inc. Souheil Saddekni was consultant at St Jude Medical.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
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References 1. Osawa T, Watarai Y, Morita K, Kakizaki H, Nonomura K. Surgery for giant high-flow renal arteriovenous fistula: experience in one institution. BJU Int. 2006;97(4):794-798. 2. Khawaja AT, McLean GK, Srinivasan V. Successful intervention for high-output cardiac failure caused by massive renal arteriovenous fistula-a case report. Angiology. 2004;55(2):205-208. 3. Matos A, Moreira A, Mendonc¸a M. Renal arteriovenous fistula after nephrectomy. Ann Vasc Surg. 1992;6(4):378-380. 4. Brountzos EN, Ptohis N, Grammenou-Pomoni M, et al. High-flow renal arteriovenous fistula treated with the Amplatzer vascular plug: implementation of an arterial and venous approach. Cardiovasc Intervent Radiol. 2009;32(3):543-547. 5. Idowu O, Barodawala F, Nemeth A, Trerotola SO. Dual use of an amplatzer device in the transcatheter embolization of a large highflow renal arteriovenous fistula. J Vasc Interv Radiol. 2007;18(5): 671-676. 6. Shih CH, Liang PC, Chiang FT, Tseng CD, Tseng YZ, Hsu KL. Transcatheter embolization of a huge renal arteriovenous fistula with Amplatzer Vascular Plug. Heart Vessels. 2010;25(4): 356-358. 7. Kato T, Takagi H, Ogaki K, Oba S, Umemoto T. Giant renal aneurysm with arteriovenous fistula. Heart Vessels. 2006;21(4): 270-272. 8. Kayser O, Scha¨fer P. Transcatheter Amplatzer vascular plugembolization of a giant postnephrectomy arteriovenous fistula combined with an aneurysm of the renal pedicle by through-
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and-through, arteriovenous access. Ger Med Sci. 2013;11:Doc01. doi:10.3205/000169. Bozgeyik Z, Ozdemir H, Orhan I, Cihangiroglu M, Cetinkaya Z. Pseudoaneurysm and renal arteriovenous fistula after nephrectomy: two cases treated by transcatheter coil embolization. Emerg Radiol. 2008;15(2):119-122. Hyams ES, Pierorazio P, Proteek O, et al. Iatrogenic vascular lesions after minimally invasive partial nephrectomy: a multiinstitutional study of clinical and renal functional outcomes. Urology. 2011;78(4):820-826. Taneja M, Lath N, Soo TB, et al. Renal artery stump to inferior vena cava fistula: unusual clinical presentation and transcatheter embolization with the Amplatzer vascular plug. Cardiovasc Intervent Radiol. 2008; 31(suppl 2):S92-S95. Bookstein JJ, Goldstein HM. Successful management of postbiopsy arteriovenous fistula with selective arterial embolization. Radiology. 1973;109(3):535-536. Ginat DT, Saad WE, Turba UC. Transcatheter renal artery embolization: clinical applications and techniques. Tech Vasc Interv Radiol. 2009;12(4):224-239. Resnick S, Chiang A.Transcatheter embolization of a high-flow renal arteriovenous fistula with use of a constrained wallstent to prevent coil migration. J Vasc Interv Radiol. 2006;17(2 pt 1): 363-367. Rimon U, Heldenberg E, Golan G, Shinfeld A, Garniek A. Amplatzer vascular plug: expanding the applications spectrum. Cardiovasc Intervent Radiol. 2008;31(suppl 2):S84-S87.
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Percutaneous Embolization of a Postnephrectomy Arteriovenous Fistula With Intervening Pseudoaneurysm Using the Amplatzer Vascular Plug 2
Vascular and Endovascular Surgery 2014, Vol. 48(7-8) 516-521 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1538574414561230 ves.sagepub.com
Ahmed Kamel Abdel-Aal, MD, MSc, PhD1, Ahmed Elsabbagh, MD1, Hesham Soliman, MD1, Maysoon Hamed, MD2, Edgar Underwood, MD1, and Souheil Saddekni, MD, FSIR, FAHA1
Abstract Although renal arteriovenous fistula (AVF) is an uncommon condition, it may lead to high cardiac output heart failure and renal insufficiency. Recently, percutaneous transcatheter embolization has replaced traditional surgery as the first line of treatment. We report a case of a 68-year-old male who presented with a renal AVF and was treated by percutaneous transcatheter embolization using the Amplatzer Vascular Plug 2 (AVP 2; St Jude Medical, Plymouth, Minnesota) through an arterial access. To our knowledge, the use of AVP 2 device in the treatment of renal AVF as a single embolotherapy device through the transarterial route has not been previously reported in the literature. Our technique demonstrates the feasibility and safety of AVP 2 device in the treatment of renal AVF. Keywords renal arteriovenous fistula, postnephrectomy, pseudoaneurysm, transcatheter embolization, Amplatzer Vascular Plug 2, coil embolization, percutaneous, embolotherapy, endovascular
Introduction
Case Report
Renal arteriovenous fistula (AVF), which is an abnormal connection between the renal artery and the vein, is a very rare condition. They are classified according to the etiology into congenital, idiopathic, or acquired types. Congenital and idiopathic types constitute less than 30% of all renal AVFs. Acquired renal AVFs maybe secondary to trauma, carcinoma, arteritis, or iatrogenic.1,2 Postnephrectomy renal AVF is a rare complication of an otherwise frequently performed procedure. Treatment of renal AVF has traditionally been surgical in the form of total or partial nephrectomy with ligation of the feeding vessel.3 Endovascular treatment, through percutaneous transcatheter embolization, has gradually replaced open surgery as the first-line therapy of renal AVFs. However, percutaneous embolization has a considerable risk of migration of the embolic materials to the venous and pulmonary circulations. Recently, the use of the Amplatzer Vascular Plug 2 (AVP 2) was described in embolization of renal AVFs in several vascular territories, more specifically in high-flow renal AVFs.4 Several authors reported the AVP 2 device to be effective and safe in treatment of renal AVFs, with decreased risk of device migration compared to other embolic material.4,5
We present a 68-year-old male patient with history of renal cell carcinoma who was treated by partial nephrectomy. The patient also had abdominal aortic aneurysm (AAA) which was treated by endovascular aortic stent graft and presented to our institution for computed tomography angiogram (CTA) of the abdomen and pelvis as part of a routine follow-up. The CTA demonstrated that the aortic stent graft was patent. However, there was contrast opacification of the renal vein during the arterial phase suggesting renal AVF, with a large Pseudoaneurysm (PSA) connecting the renal artery and renal vein at the site of left partial nephrectomy (Figure 1). The clinical team was concerned about the potential rupture of the large PSA, and due to the patient’s associated
1 Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA 2 Department of Family Medicine, University of Alabama, Tuscaloosa, AL, USA
Corresponding Author: Ahmed Kamel Abdel-Aal, Department of Radiology, University of Alabama at Birmingham, 619 19th street south, Birmingham, AL 35249, USA. Email: [email protected]
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Figure 1. A 68-year-old male patient with history of renal cell carcinoma treated by partial nephrectomy. A, Axial computed tomography (CT) angiogram image showing contrast opacification of the renal vein (arrowheads) during the arterial phase suggesting renal arteriovenous fistula, with a large pseudoaneurysm (large arrow) connecting the upper pole renal artery branch (small arrow) and renal vein at the site of left partial nephrectomy. B, Coronal CT angiogram image showing the arterial feeder (curved arrow) and the large pseudoaneurysm (asterisk).
Figure 2. Aortogram showing a large pseudoaneurysm (asterisk) involving the upper pole of the left kidney with early opacification of the renal vein (small arrow).
comorbidities, an interdisciplinary consensus opted to offer the patient a minimally invasive treatment. Therefore, the patient was referred to our Interventional Department for percutaneous transcatheter embolotherapy of the renal AVF and the associated large PSA. The patient was brought to our angiosuite, and right common femoral artery access was obtained. The initial aortogram showed a large PSA involving the upper pole of the left kidney with early opacification of the renal vein, consistent with a renal AVF (Figure 2). The right renal artery was then catheterized using 5F catheter (RC2; Cook, Bloomington, Indiana) and angiogram was performed, which showed a large PSA fed by one of the upper pole branches of the renal artery and draining directly into the renal vein (Figure 3). A 2.8F microcatheter
(Miraflex; Merit, South Jordan, Utah) was then advanced into the PSA, and 3 variable-sized detachable hydrogel coils (Azur; Terumo, Tokyo, Japan) were deployed into the PSA (Figure 4). During deployment, the third coil migrated through the renal vein to a left inferior pulmonary artery branch. The migrated coil was retrieved using a snare (Goose neck snare; Covidien, Plymouth, Minnesota) through a right femoral vein approach (Figure 5). The renal AVF remained patent. In order to prevent further coil migration, an occlusion balloon catheter (Fogarty; Edwards Lifesciences, Irvine, California) was inflated in the renal vein close to the PSA to occlude the renal AVF outflow (Figure 6). Several hydrogel coils were then deployed as mentioned earlier. Thrombosis of the PSA was then augmented by slowly injecting 300 units of thrombin into the PSA. The occlusion balloon was deflated and follow-up angiogram showed absent flow in the PSA, denoting occlusion of the renal AVF. The procedure was terminated, and the patient was discharged home after an uneventful 24 hours of observation. A routine follow-up CTA performed 2 months after the procedure to evaluate the aortic stent graft showed interval recanalization of the renal AVF, with several metal artifacts related to preexisting coils in PSA (Figure 7). Therefore, the patient was referred to our service again for further evaluation and treatment. The right common femoral artery was accessed and a 6F sheath (Flexor Ansel sheath; Cook, Bloomington, Indiana) was placed at the origin of the left renal artery. A 6F guiding catheter (Launcher; Medtronic, Minneapolis, Minnesota) was then advanced into the upper pole branch that feeds the renal AVF, and angiogram was performed and demonstrated preexisting coils residing in the PSA, with recanalization of the renal AVF (Figure 8A). At this point, a 6-mm AVP 2 was placed at the junction of the feeding artery and the PSA (Figure 8B). Position was then confirmed by angiogram, and the device was deployed. Follow-up angiogram performed from the main renal artery showed occlusion of the feeding artery with absent filling of the PSA denoting successful embolization (Figure 8C).
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Figure 3. A, Left renal angiogram showing a large pseudoaneurysm (asterisk) fed by one of the upper pole branches of the renal artery (curved arrow) and (B) draining directly into the renal vein (arrowheads).
Figure 4. Multiple variable-sized detachable hydrogel coils deployed in the pseudoaneurysm (arrowheads), using a 2.8F microcatheter (small arrow).
The patient had an unremarkable recovery and was discharged home in a stable condition. Follow-up CTAs done 4 and 10 months after the procedure and showed AVP 2 device residing in the left renal artery branch feeder without artifacts. There was no evidence of recanalization of the renal AVF (Figure 9).
Discussion The first renal AVF was reported by Vorela in 1928.1,6,7 The prevalence of renal AVF is less than 0.04%.6 Renal AVFs are classified according to their etiology into congenital, idiopathic, and acquired types. Congenital renal AVF arise from errors in vascular morphology and represent 14% to 27% of cases. Acquired renal AVF represents the majority of cases constituting about 70% to 80% of cases. Acquired renal AVF may result from trauma, malignancy, inflammation, or may be iatrogenic as in case of prior surgery.2,6,8,9 Congenital renal AVF consists of multiple communicating channels, while the acquired renal AVFs are characterized by having a single communicating channel between a single feeding artery and single draining vein.4 Postnephrectomy renal
Figure 5. Left pulmonary angiogram showing a migrated detachable hydrogel coil lodged in the left inferior pulmonary artery branch (arrowheads).
AVF occurs following partial nephrectomy for infectious or neoplastic etiology and is usually accompanied by PSA.3 The reported incidence of renal AVF and PSA after open partial nephrectomy is less than 0.5%.9 Our case represents an acquired renal AVF following open upper pole partial nephrectomy for renal cell carcinoma. The detailed pathophysiology of acquired renal AVF is not completely understood. The blunt-ended ligated renal artery subsequent to partial nephrectomy may distort the shear stress to the wall of the renal artery which seems to predispose to the formation of aneurysms. The contact of the pulsatile aneurysm to the adjacent vein may cause erosion of the venous vessel wall, which subsequently develops a communication and the formation of a renal AVF.6,8
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Figure 6. Inflated occlusion balloon catheter (small arrow) was placed in the left renal vein through a transfemoral vein route to prevent further coil migration from the pseudoaneurysm (large arrow).
Figure 7. Axial image from a routine follow-up computed tomography (CT) angiogram performed 2 months after the procedure to evaluate the aortic stent graft shows interval recanalization of the renal arteriovenous fistula, with contrast opacification of the left renal vein (curved arrow) during the arterial phase. Metal artifacts are related to preexisting coils in pseudoaneurysm (large arrow).
The presentation and diagnosis of renal AVF are occasionally achieved late, with some cases reported up to 40 years following nephrectomy (mean 14.5 years).2,8 Common manifestations of the renal AVF are abdominal bruit (90%-100% of cases), hypertension and cardiomegaly (60%-80% of cases), congestive heart failure (30%-40% of cases), gross hematuria (40% of cases), and pain (20% of cases).3,6,7,8 Although most patients present with one or more of the above-mentioned symptoms and signs, there are sporadic reports of incidental diagnosis of renal AVF.10 In our asymptomatic patient, the renal AVF was incidentally diagnosed during a CTA performed as part of routine follow-up for the patient’s AAA, which was previously treated by endovascular aortic stent graft. Computed tomograhy (CT) is considered more accurate than ultrasound in the detection and the demonstration
of the exact angioarchitecture of renal AVF. However, the gold standard technique for imaging remains catheter angiography. The latter enables diagnosis with ability to intervene in the same session.2,3,8,10,11 The indication for treatment of postnephrectomy renal AVFs includes progressive increase in size, impending rupture, recurrent or persistent hematuria, hypertension, pain, and, above all, when there is a risk of heart failure.2,3,5,10 In our case, the indication for treatment was the large PSA with concern for potential rupture. Endovascular transcatheter embolization is considered the first-line therapy because it has a high success rate and shorter hospital stay, combined with lower morbidity and mortality compared to surgery, which is more invasive and confers the risk of intraoperative anesthesia.5,9 Transcatheter embolization of renal AVF was first described by Bookstein and Goldstein in 1973,12 and numerous techniques and embolization materials have been reported since, including metallic coils, sclerozing liquid agents, and particulate embolization material.13 Paradoxical embolization, which is a potentially serious complication, limited the use of the last 2 agents.14 In our case, we started the embolization process using coils but due to paradoxical embolization of one of the coils to the lung, we decided to use the AVP 2 device. In the authors’ opinion, coils should only be used when secure placement is guaranteed, which can be achieved using balloon occlusion from the arterial or venous side to help reduce the flow. Alternatively, AVP 2 should be used which offers a more accurate and stable placement through a detachable system. The AVP 2 is a self-expanding, cylindrical occluding device made out of nitinol mesh wires. The device is secured at both ends with platinum marker bands. A stainless steel microscrew is welded to one of the platinum marker bands, which allows attachment to the 135-cm long delivery cable. The diameter of the AVP 2 ranges from 3 to 22 mm. It can be safely used in high-flow, short-vascular segments, such as renal AVF, where coils are less accurately and safely released. After placement of the device, angiograms can be performed to confirm location, and the device can then be deployed from the pusher wire in a relatively precise, controllable, intentional fashion by rotating the pusher wire. The device can be retrieved and repositioned, if the location is unsatisfactory, thus minimizing the risk of migration. Additionally, the device is usually oversized by 30% to 50% of the size of the target vessel which offers more stability in the deployed vessel, with less chances of migration. Additionally, the AVP 2 is better than detachable coils because only one device is needed to occlude the renal AVF.8,15 Several authors recommended AVP 2 as the first choice for occlusion of a renal AVF with high-flow and short-vascular connection, where the occlusion has to be in an exact location.15 Others document the cost-effectiveness of using this device compared to coils.5 The AVP 2 also has a distinctive appearance on computed tomography, with significantly less metal artifact compared to coils (Figure 9), allowing more accurate interpretation of follow-up studies.11 However, the AVP 2 device is usually delivered through a sheath or guiding
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Figure 8. A, Left renal angiogram showing the feeding arterial branch supplying the pseudoaneurysm (small arrow). Preexisting coils (large arrow) are seen residing in the contrast filled pseudoaneurysm (curved arrow), suggesting recanalization of the renal arteriovenous fistula. B, A nonsubtracted image showing the Amplatzer vascular plug 2 (curved arrow) placed at the junction of the feeding artery and the pseudoaneurysm. C, Follow-up angiogram performed from the main renal artery shows occlusion of the feeding artery (large arrow) by the Amplatzer vascular plug 2 with absent filling of the pseudoaneurysm denoting successful embolization.
relatively stiff compared to that of detachable coils, which might pose difficulty in advancing the device in tortuous anatomy.
Conclusion Our case demonstrates the feasibility of the use of AVP 2 in the treatment of renal AVF through embolization of the arterial feeder, especially in high-flow fistulas with short communication. In our case, the device offered several advantages over coils and appeared to be more cost effective.
Figure 9. Axial image of a computed tomography (CT) angiogram showing Amplatzer vascular plug 2 (small arrow) residing in the left renal artery branch feeder with minimal artifacts. There is absent contrast opacification of the left renal vein (large arrow) during the arterial phase, with no evidence of recanalization of the renal arteriovenous fistula.
catheter which might be difficult to place through stenotic renal arteries or distally in the renal vasculature where most of these fistulas are encountered. Furthermore, the delivery cable is
Declaration of Conflicting Interests The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Ahmed K. Abdel-Aal was consultant at St Jude Medical, Baxter Heathcare Coorporation, and Bard Peripheral Vascular, Inc. Souheil Saddekni was consultant at St Jude Medical.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
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