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Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions
Author's Accepted Manuscript
Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions G. Vatakencherry MD, Ripal Gandhi MD, Christopher Molloy MD
www.elsevier.com/locate/enganabound
PII: DOI: Reference:
S1089-2516(16)30004-X http://dx.doi.org/10.1053/j.tvir.2016.04.004 YTVIR485
To appear in: Tech Vasc Interventional Rad
Cite this article as: G. Vatakencherry MD, Ripal Gandhi MD, Christopher Molloy MD, Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions, Tech Vasc Interventional Rad , http://dx.doi.org/10.1053/j.tvir.2016.04.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions Authors: G.Vatakencherry MD1, Ripal Gandhi MD2, Christopher Molloy MD1 Author Affiliations: 1Kaiser Permanente Los Angeles Medical Center, 2Miami Cardiac and Vascular Institute, Miami, Florida Correspondence: [email protected] ABSTRACT Vascular interventionalists continue to expand the scope and breadth of endovascular procedures that we offer to our patients. However, we often have to overcome various anatomic and technical challenges in order to deliver an endovascular device. This article should give the modern interventionalist an array of technical tips and tricks to enable them to overcome various challenging anatomic features such as vessel tortuosity, vascular calcifications, increasing abdominal pannus. We also hope to elucidate alternative accesses such as radial access, pedal access, popliteal access, direct stent access as well as direct aortic access. ARTICLE Ever since Sven Ivar Seldinger discovered the concept of needle in, wire in, needle out and catheter in, interventional radiologists have been utilizing this technique to gain access to various areas in the human body to perform diagnostic angiography. Subsequently Charles Dotter showcased to the world of medicine that a remote percutaneous vascular access can enable us to perform elegant minimally invasive endovascular procedures without a scalpel. For the last 50 years vascular interventional physicians have been able to push the envelope and have developed solutions for dealing with challenging vascular anatomy. We are performing far more complex interventions and often require the delivery of devices as large as 26 French in size. Some challenging factors such as small-caliber vessels, vessel tortuosity, calcified vessels, and abdominal pannus are hurdles all clinical interventionalists face. The purpose of this article is to specifically provide a few tips and tricks to overcome challenging anatomies and complex conditions with regard to endovascular interventions. Ipsilateral Retrograde CFA Access For lower extremity interventions, a commonly preferred route is to go “up and over” the aortic bifurcation which in general can be performed with a standard Cobra catheter or a reverse curve catheter (Omniflush catheter, Angiodynamics) . Steep angled aortic bifurcations or the need to deliver large caliber sheaths via a contralateral approach may pose some unique challenges. Furthermore, the presence of an aortic endograft, kissing common iliac stents, or aortic bypass surgery (i.e. aortobifemoral bypass) can make a crossover approach difficult or impossible. One may consider an antegrade access to perform ipsilateral lower extremity interventions which may also provide some mechanical advantage for chronic total occlusions as well as allow for shorter lengths of devices and wires.
The authors advocate using all of your tools to optimize the initial entry into the common femoral artery. This begins with pre-operative planning. Many patients will have a prior CT scan of the pelvic region for other reasons and this can be very useful to evaluate for vessel size, degree of calcification, atherosclerotic burden and location of common femoral artery bifurcation. There is a great deal of variability in the interventional community on the optimal method to access the common femoral artery. Some use external anatomic landmarks such as anterior superior iliac spine and pubic symphysis and palpate the point of maximal impulse of the femoral artery to determine access site.
Figure 1: Illustration depicting the common femoral access zones. Zone A represents the region superior to the femoral head, Zone B is the superior 50% of the femoral head, Zone C is the inferior 50% of the femoral head, and Zone D is the region below the femoral head. CFA access is recommended at the junction of zones B & C.1 (Illustration by: C.Molloy)
Others use the inferior margin of the femoral head and attempt to have the access at the level of the mid portion of the femoral artery which corresponds to the junction of Zone B & Zone C in Figure 1. Others use ultrasound landmarks including the anisotropic bands that signify the inguinal ligament, deep circumflex iliac artery and the inferior epigastric origins as the site where the external iliac artery ends as well as to identify where the profunda and superficial femoral artery (SFA) bifurcate. Also, it is preferable to access the anterior aspect of the femoral artery in a non-calcified area and this is best achieved using direct ultrasound visualization. There is a learning curve for any of these techniques, but the most accurate method is using ultrasound. It is also important to bluntly dissect the soft tissues superficial to the arteriotomy as demonstrated in Figure 2, to “prep” for closure. The authors use ultrasound to perform blunt dissection to the level of the femoral arteriotomy.
Another important consideration is the growing epidemic of obesity in the western world. This can pose various challenges to the endovascular specialists. Things to consider are alternative routes such as the radial artery. Marked obesity can make antegrade access much more risky. In these cases it is vital to tape the pannus upward using robust taping methods and, in some cases, may require an additional operator to hold up the pannus during arterial access as well as closure. Squeezing down on the fat which is often compressible may decrease skin to artery distance as well. It is also imperative to use ultrasound to obtain access, as the inguinal crease does not reflect the location of the inguinal ligament. The operator should have experience with closure devices in order to prevent an access site complication from maldeployment of a vascular closure device.
Figure 2: Ultrasound guided real time dissection of the subcutaneous tissues superficial to the arteriotomy site in anticipation of utilization of a closure device.
Steep Angled Bifurcations
Figure 3: Angiogram demonstrating a steep angle aortoiliac bifurcation
Occasionally steep angled iliac bifurcations as encountered in Figure 3 may present a challenge to access, which may be further complicated by tortuous or calcified vessels. The fundamental challenge in these cases will be to direct a wire over the bifurcation and into the opposite iliac artery, over which a sheath can be advanced for contralateral limb interventions. The techniques entailed may include using a Cobra shaped catheter or a reverse curve catheter (Sos shape, Simmons etc) and then advancing a wire that is steerable and with adequate body to allow for sheath placement. One may even consider using a stiffer wire platform such as an amplatz guidewire or even a Lunderquist as they will straighten the aortic bifurcation curve after advancing a regular hydrophilic glidewire down to the contralateral groin or leg and then exchanging for the stiffer wire via a 4 French glidecatheter or crossing catheter. If the sheath still does not track over the bifurcation other alternatives would include using a longer dilator to allow for a smoother crossover transition (i.e. using the dilator from a 70 cm sheath in a 45 cm sheath) as illustrated in Figure 4. Another consideration is to inflate a 4 or 5 mm semi-compliant balloon and subsequently advancing the sheath over the balloon as it is deflated (this technique is illustrated in Figure 5). Alternatively a torqueable sheath such as the Tourguide (Aptus/Medtronic), Morph (BioCardia), or Destino (Oscor) would also be reasonable alternatives. A newer innovative solution is utilization of a Magellan robotic catheter (Hansen Medical) (Figure 6) which allows for multidirectional control of the intravascular catheter as well as unparalleled stability. Figure 8 and 9 demonstrate the use of a Magellan robotic catheter in navigating up and over a steep bifurcation to deploy an occlusion device in a contralateral hypogastric artery. A last option to consider for delivering large crossover sheaths is to snare the sheath over the aortic bifurcation via the contralateral femoral artery and thus provide a rail on which most any sheath should track
For tortuous iliac arteries it also may be difficult to track sheaths over, and in these instances it is important to get a long braided up and over sheath of adequate size to deliver the endovascular devices, as demonstrated in Figure 7.
Figure 4: Illustration demonstrating progressive advancement of a sheath over dilator for improved stability when crossing difficult aortic bifurcations. A) sheath and dilator approaching steep bifurcation. B) dilator advanced over a wire over the steep bifurcation. C) Sheath advanced across the steep bifurcation over the dilator and wire. (Illustration by: C.Molloy)
Figure 5: Illustration demonstrates advancing the sheath over balloon for improved stability when crossing difficult aortic bifurcations. A) Sheath approaching steep bifurcation with inflated balloon for improved stability. B) The sheath is advanced over the partially deflated balloon to navigate the steep aortic bifurcation. (Illustration by: C.Molloy)
Figure 6: Magellan Robotic Catheter (Hansen Medical) indicated by the blue arrow, covered in sterile plastic
Figure 7A: Catheterization up and over the aortoiliac bifurcation demonstrating extreme vessel tortuosity of the left common iliac, extending into the right external iliac, use of through and through access with angled glide catheter and glidewire to navigate the tortuousity
Figure 7B:16 French sheath up and over, through and through access with stiff buddy wire from contralateral left common iliac to the right external iliac. In non-calcified vessels, large bore sheaths can be used to track up and over the aortic bifurcation.
Figure 7C: Completed deployment of stent extension limb into internal iliac for hypogastric artery preservation
Figure 7D: Completion angiogram with 16 French sheath at the level of the aortic bifurcation
Figure 8: A) Aortogram demonstrates steep aortic bifurcation. This was technically difficult to navigate with manual catheterization. B) The 9 French Magellan robotic system (Hansen Medical) was utilized to cross up and over the aortic bifurcation and select the contralateral hypogastric artery. C) Hypogastric angiogram was performed from the 6 Fr Leader catheter of the robotic system.
Figure 9: A) Magnified angiogram of the right hypogastric artery performed via the Magellan robotic catheter. B) An 8 mm Amplatzer 4 device (St.Jude Medical) was deployed through the 6 French Leader catheter of the robotic system. C) The Amplatzer 4 device (St.Jude Medical) was successfully deployed. D) Post embolization angiogram demonstrates successful occlusion of the hypogastric artery at its origin.
When the ipsilateral and contralateral CFA access is simply not an option, several other alternative access sites throughout the lower and upper extremity vasculature may be viable options. Although there may be multiple alternative sites which may be utilized for vascular access, each site carries unique risks which must be considered prior to establishing access. Because each of these vessels are smaller than the CFAs and may present with more variable anatomy, ultrasound evaluation is recommended. Superficial Femoral Artery (SFA) Access Sometimes it is difficult to access the common femoral artery due to excessive obesity, scarred or hostile groin or very high riding femoral artery bifurcation. In these cases an alternative is to use the SFA for arterial access in a retrograde or antegrade fashion as demonstrated in Figure 10. Antegrade access via the superficial femoral artery (SFA) has been demonstrated as a safe access site for treatment of peripheral vascular disease.2,3,4 The SFA may be accessed with either 19g or 21g micropuncture needle with no significant difference in complication rates.5 In the setting of scarred groins, obesity or failed CFA access, some studies demonstrated that antegrade SFA access can have more favorable outcomes when compared with traditional CFA access.6 The main consideration when accessing from the SFA is the presence of variable anatomy, however ultrasound guidance of SFA access is commonly very successful. It is important to bluntly dissect the tissue to prep access and facilitate closure device use. Additional consideration for SFA access (or any site distal to the SFA) is the presence of a smaller vessel lumen which will limit the size of devices used. The rate of pseudoaneurysm formation may be higher with SFA access compared to common femoral access. Also, sometimes the interventionalist will face an occluded SFA stent that is impossible to cross from above or even via a pedal or popliteal approach. In these instances it may be reasonable to directly puncture the SFA stent using fluoroscopic and ultrasound guidance. It is best to try to minimize the access size by using a 20 gauge chiba needle or micropuncture needle and 018 wire system. Then once the stent is traversed the wire can be snared from a contralateral or antegrade CFA access. At this point we can advance the sheath into the SFA stent and proceed to recanalizing the stent. At this point once flow is demonstrated you can pull back the 018 wire out and perform angiography to exclude any significant extravasation. If there is significant extravasation you can usually control this with prolonged balloon inflation or even use a covered stent to plug the hole.
Figure 10: A) Axial CT demonstrating a high bifurcation of the Left CFA(blue arrow) in a patient with a ruptured left common iliac aneurysm (which is not shown). B) CO2 angiogram with percutaneous access directly into the left SFA with an 18 French sheath. C) Completion CO2 angiogram via direct SFA access. Popliteal Artery (PA) Access Both antegrade and retrograde access via the popliteal artery (PA) have been demonstrated to be safe.7,8 Early popliteal access implemented prone positioning9 (as demonstrated in Figure 11), which some patients were not able to tolerate. Fortunately, with evolving techniques patients may remain supine with their leg in external rotation with slight flexion (demonstrated in Figure 12) to gain medial access to the PA.10 Ultrasound access is highly recommended to visualize path directly into popliteal artery as well as to avoid the overlying popliteal vein. A 6 French 25cm long sheath may be used for antegrade access and a 45 cm introducer sheath may be used for retrograde access.11 In addition, due to the smaller caliber of the popliteal artery, one could consider using a micropuncture needle and 018 wire system to gain access via the popliteal artery and then utilize a contralateral access or antegrade common femoral artery access to snare the wire and then use the common femoral artery access to introduce devices for peripheral arterial interventions which may reduce the potential bleeding complications.
Figure 11: Right popliteal access with the patient in a prone position using a 6 French sheath.
Figure 12: Right popliteal access with the patient in a “frog leg” position with external hip rotation and slight knee flexion using a 6 French sheath. Pedal Access In lower extremity arterial revascularization it has been noted that sometimes an occlusive cap is easier to traverse from the distal aspect. It is feasible using a combination of ultrasound and fluoroscopy to access all 3 tibial vessels and the pedal arteries. Retrograde pedal access is demonstrated in Figures 13 and 14. Many operators are using low profile systems to revascularize the tibial circulation with balloon angioplasty or adjunctive techniques such as orbital atherectomy or laser atherectomy from a purely pedal approach. Most operators prefer to use a snare catheter or guidecatheter to externalize the pedal wire from an antegrade common femoral artery or superficial femoral artery access.
Figure 13: Retrograde pedal access with placement of a pedal micropuncture and 4 French sheath (Cook Medical). Pedal access may be achieved with either ultrasound or fluoroscopic guidance. Although the former is preferred, in patients with significant calcific disease, fluoroscopic guidance is utilized.
Figure 14A: Retrograde pedal access in a patient with necrotic toes. Recanalization of an occluded popliteal artery and anterior tibial artery had failed from an antegrade femoral approach and therefore the dorsalis pedis was accessed with a micropuncture needle with ultrasound guidance.
Figure 14B: Fluoroscopic spot image demonstrates successful wire advancement into the anterior tibial artery. Aortic access: With the increasing utilization of endovascular aneurysm repair the interventional community are identifying more type 2 endoleaks with aneurysm sac enlargement. These may not be amenable to access via a trans-arterial route or may not be easily identifiable even on conventional angiography. Another method of gaining access to these challenging endoleaks is with direct aortic sac entrance via a translumbar route. Some operators use fluoroscopy and anatomic landmarks as their initial guide. We feel it is safer to access these percutaneously under CT guidance from a posterior approach using 20 cm sheath needles (as demonstrated in Figure 15) and then once arterial blood is confirmed (Figure 16), taking them to the interventional suite for completion of the aneurysm embolization as demonstrated in Figure 17. Alternatively, cone beam CT guidance tools can be extremely valuable in this setting and can allow for direct access into the aortic sac without having to move the patient. Under fluoroscopy an 035 guidewire and a 5 French 25 cm vascular sheath may be placed, through which one can place 5 French catheters and navigate the aortic sac and deliver large diameter coils and liquid embolic material as well. Another approach is to deliver a microcatheter directly through the sheath needle and this avoids having to upsize the access. Another approach to access the aortic sac is via a transcatheter transcaval approach in which venous access is achieved via the femoral vein or internal jugular veins. It is important to evaluate the preprocedural imaging to ensure there is adherence of the IVC to the aortic wall. A 10 Fr, 40 cm reinforced angled sheath similar to that used for TIPS procedures is directed towards the aorta and a small amount of contrast is administered to ensure the sheath is wedged. A Colapinto needle (Cook Medical) is then directed into the aorta using fluoroscopic and/or intravascular ultrasound guidance. This approach is used for both treatment of type II endoleaks as well as performing aortic procedures requiring large sheaths in patients who have significant iliac disease which would preclude placement of a large caliber sheath. For the latter indication, electrocautery attached to a guidewire (i.e. Confianza, Abbott Medical) has also been utilized to traverse the caval wall and enter the aorta. At the completion of the procedure, the aorto-caval connection may be closed with a VSD occluder (St Jude Medical) to prevent a fistula.
Figure 15: Axial CT images demonstrating direct percutaneous aortic aneurysm sac access A) A percutaneous 5 French sheath needle tip entering the psoas muscle. B) The percutaneous needle tip is entering the aneurysm sac. C) The percutaneous needle tip has entered the aortic aneurysm sac.
Figure 16: Direct percutaneous aneurysm sac access with sheath needle demonstrating arterial blood return
Figure 17: Image series demonstrating direct percutaneous aortic aneurysm sac access and coil embolization of a type II endoleak. A) 5 Fr vascular sheath with 5 Fr angled braided catheter. B) Introduction of coils into the aortic aneurysm sac. C) Completion image demonstrating coils within the aortic aneurysm sac.
Radial Access Radial Artery access has traditionally been used for coronary interventions. Many interventional groups are utilizing this as a primary route for vascular interventions as there are fewer complications then a brachial route as well as improved patient satisfaction and comfort. It is critical to perform an Allen‟s test or Barbeau test prior to accessing the radial artery to prevent hand ischemia. A Barbeau D waveform is an absolute contraindication to radial access. At the end of the procedure it is critical to achieve hemostasis while maintaining hand perfusion . There are several proprietary devices used to maintain patent hemostasis. There are a few key things to sort out when doing radial artery interventions including using adequate vasodilators. Some prep the radial artery with EMLA and nitropaste prior to puncture. Some use an angiocath (doublewall technique) to go through and through the artery and then advance the microwire and then advance a lower profile sheath. Others use a micropuncture needle to access the artery and then after gaining access will give a cocktail of 200 micrograms of nitroglycerine, 2.5 mg of verapamil, and 3000 units of heparin (as demonstrated in Figure 18). An important technical point is to aspirate blood into the drug cocktail described prior to injection because the verapamil can be painful if not diluted. Utilization of hydrophilic sheath is mandatory. At the current time, the primary limitation of radial access for lower extremity interventions is the lack of endovascular tools of sufficient length. The iliac artery, common femoral artery, and proximal SFA may be treated with current technology. Upon conclusion of the procedure, hemostasis may be optimized by the use of a TR band (Terumo) which provides dual compression balloons which compress the radial artery, while sparing the nerves and simultaneously allowing for visualization of the access site to ensure hemostasis is achieved (as shown in Figure 19).
Figure 18: Radial artery access with aspiration of blood into drug cocktail consisting of 2.5 mg of verapamil, 200 mcg nitroglycerin, and 3000 units of heparin prior to injection. It is important to dilute the drugs with the patient‟s own blood prior to injection because verapamil injection can be painful otherwise.
Figure 19: Radial artery access with placement of TR band (Terumo) for patent hemostasis. The TR band is has dual compression balloons to provide compression of the radial artery without compressing the nerves. The transparent nature of device is designed to allow for visualization of the access site to ensure hemostasis is achieved.
Summary: In the past 50 years since Charles Dotter invented vascular interventions, we have come a long way with the concept of “surgery without a scalpel”. In order to overcome more and more challenging anatomy we have had to identify unique avenues to gain vascular access. We hope that this chapter will give you some practical pearls and allow you to treat some of the more complex vascular anatomies and vascular conditions that you may face.
1
A.M Amin, B. Holloway, G.G. Vatakencherry, CT Scanning for CFA Calcification in the Use of Vascular Access Closure Devices, Abstract No. 148, J Vasc Interv Radiol 2009; 20:S58 2 Andreas Gutzeit, MD, Eric Schoch, MD, Thomas Sautter, MD, Regula Jenelten, MD, Nicole Graf, PhD, and Christoph A. Binkert, MD, MBA, Antegrade Access to the Superficial Femoral Artery with Ultrasound Guidance: Feasibility and Safety, J Vasc Interv Radiol 2010; 21:1495–1500 3 Michelle Kweon, Venu Bhamidipaty, Andrew Holden, and Andrew A. Hill, Antegrade Superficial Femoral Artery versus Common Femoral Artery Punctures for Infrainguinal Occlusive Diseas, J Vasc Interv Radiol 2012; 23:1160– 1164 4 Gutzeit A, Graf N, Schoch E, Sautter T, Jenelten R, Binkert CA, Ultrasound-guided antegrade femoral access: comparison between the common femoral artery and the superficial femoral artery. Eur Radiol. 2011 Jun;21(6):1323-8. 5 Andreas Gutzeit, Eric Schoch, Carolin Reischauer, Klaus Hergan, Regula Jenelten, Christoph A. Binkert, Comparison of a 21G Micropuncture Needle and a Regular 19G Access Needle for Antegrade Arterial Access into the Superficial Femoral Artery, Cardiovasc Intervent Radiol (2014) 37:343–347 6 Adrian J. Marcus, Kevin Lotzof, Adam Howard, Access to the Superficial Femoral Artery in the Presence of a „„Hostile Groin‟‟: A Prospective Study, Cardiovasc Intervent Radiol (2007) 30:351–354 7 Andrew J. Feiring and Amy A. Wesolowski, Antegrade Popliteal Artery Approach for the Treatment of Critical Limb Ischemia in Patients With Occluded Superficial Femoral Arteries, Catheterization and Cardiovascular Interventions 69:665–670 (2007) 8 HK Younes, HF El-Sayed, MG Davies, Retrograde transpopliteal access is safe and effective-it should be added to the vascular surgeon's portfolio, Ann Vasc Surg. 2015 Feb;29(2):260-5 9 Elias N. Brountzos, Konstantinos G. Moulakakis, Efthimios D. Avgerinos, Ilias Dalainas, Triantafillos G. Giannakopoulos, John Kakisis, Nikolaos D. Ptohis, Ourania Preza and Christos D. Liapis, Retrograde Transpopliteal Approach of Iliofemoral Lesions, Vascular and Endovascular Surgery, 45(7) 646-650 10 Meng Ye, Hao Zhang, Xiaozhong Huang, Yaxue Shi, Qiuying Yao, Lan Zhang, and Jiwei Zhang, Retrograde popliteal approach for challenging occlusions of the femoral-popliteal arteries, J Vasc Surg 2013;58:84-9 11 Fabrizio Fanelli, Pierleone Lucatelli, Massimiliano Allegritti, Mario Corona, Plinio Rossi, and Roberto Passariello, Retrograde Popliteal Access in the Supine Patient for Recanalization of the Superficial Femoral Artery, J Endovasc Ther, 2011;18:503–509
Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions G. Vatakencherry MD, Ripal Gandhi MD, Christopher Molloy MD
www.elsevier.com/locate/enganabound
PII: DOI: Reference:
S1089-2516(16)30004-X http://dx.doi.org/10.1053/j.tvir.2016.04.004 YTVIR485
To appear in: Tech Vasc Interventional Rad
Cite this article as: G. Vatakencherry MD, Ripal Gandhi MD, Christopher Molloy MD, Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions, Tech Vasc Interventional Rad , http://dx.doi.org/10.1053/j.tvir.2016.04.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions Authors: G.Vatakencherry MD1, Ripal Gandhi MD2, Christopher Molloy MD1 Author Affiliations: 1Kaiser Permanente Los Angeles Medical Center, 2Miami Cardiac and Vascular Institute, Miami, Florida Correspondence: [email protected] ABSTRACT Vascular interventionalists continue to expand the scope and breadth of endovascular procedures that we offer to our patients. However, we often have to overcome various anatomic and technical challenges in order to deliver an endovascular device. This article should give the modern interventionalist an array of technical tips and tricks to enable them to overcome various challenging anatomic features such as vessel tortuosity, vascular calcifications, increasing abdominal pannus. We also hope to elucidate alternative accesses such as radial access, pedal access, popliteal access, direct stent access as well as direct aortic access. ARTICLE Ever since Sven Ivar Seldinger discovered the concept of needle in, wire in, needle out and catheter in, interventional radiologists have been utilizing this technique to gain access to various areas in the human body to perform diagnostic angiography. Subsequently Charles Dotter showcased to the world of medicine that a remote percutaneous vascular access can enable us to perform elegant minimally invasive endovascular procedures without a scalpel. For the last 50 years vascular interventional physicians have been able to push the envelope and have developed solutions for dealing with challenging vascular anatomy. We are performing far more complex interventions and often require the delivery of devices as large as 26 French in size. Some challenging factors such as small-caliber vessels, vessel tortuosity, calcified vessels, and abdominal pannus are hurdles all clinical interventionalists face. The purpose of this article is to specifically provide a few tips and tricks to overcome challenging anatomies and complex conditions with regard to endovascular interventions. Ipsilateral Retrograde CFA Access For lower extremity interventions, a commonly preferred route is to go “up and over” the aortic bifurcation which in general can be performed with a standard Cobra catheter or a reverse curve catheter (Omniflush catheter, Angiodynamics) . Steep angled aortic bifurcations or the need to deliver large caliber sheaths via a contralateral approach may pose some unique challenges. Furthermore, the presence of an aortic endograft, kissing common iliac stents, or aortic bypass surgery (i.e. aortobifemoral bypass) can make a crossover approach difficult or impossible. One may consider an antegrade access to perform ipsilateral lower extremity interventions which may also provide some mechanical advantage for chronic total occlusions as well as allow for shorter lengths of devices and wires.
The authors advocate using all of your tools to optimize the initial entry into the common femoral artery. This begins with pre-operative planning. Many patients will have a prior CT scan of the pelvic region for other reasons and this can be very useful to evaluate for vessel size, degree of calcification, atherosclerotic burden and location of common femoral artery bifurcation. There is a great deal of variability in the interventional community on the optimal method to access the common femoral artery. Some use external anatomic landmarks such as anterior superior iliac spine and pubic symphysis and palpate the point of maximal impulse of the femoral artery to determine access site.
Figure 1: Illustration depicting the common femoral access zones. Zone A represents the region superior to the femoral head, Zone B is the superior 50% of the femoral head, Zone C is the inferior 50% of the femoral head, and Zone D is the region below the femoral head. CFA access is recommended at the junction of zones B & C.1 (Illustration by: C.Molloy)
Others use the inferior margin of the femoral head and attempt to have the access at the level of the mid portion of the femoral artery which corresponds to the junction of Zone B & Zone C in Figure 1. Others use ultrasound landmarks including the anisotropic bands that signify the inguinal ligament, deep circumflex iliac artery and the inferior epigastric origins as the site where the external iliac artery ends as well as to identify where the profunda and superficial femoral artery (SFA) bifurcate. Also, it is preferable to access the anterior aspect of the femoral artery in a non-calcified area and this is best achieved using direct ultrasound visualization. There is a learning curve for any of these techniques, but the most accurate method is using ultrasound. It is also important to bluntly dissect the soft tissues superficial to the arteriotomy as demonstrated in Figure 2, to “prep” for closure. The authors use ultrasound to perform blunt dissection to the level of the femoral arteriotomy.
Another important consideration is the growing epidemic of obesity in the western world. This can pose various challenges to the endovascular specialists. Things to consider are alternative routes such as the radial artery. Marked obesity can make antegrade access much more risky. In these cases it is vital to tape the pannus upward using robust taping methods and, in some cases, may require an additional operator to hold up the pannus during arterial access as well as closure. Squeezing down on the fat which is often compressible may decrease skin to artery distance as well. It is also imperative to use ultrasound to obtain access, as the inguinal crease does not reflect the location of the inguinal ligament. The operator should have experience with closure devices in order to prevent an access site complication from maldeployment of a vascular closure device.
Figure 2: Ultrasound guided real time dissection of the subcutaneous tissues superficial to the arteriotomy site in anticipation of utilization of a closure device.
Steep Angled Bifurcations
Figure 3: Angiogram demonstrating a steep angle aortoiliac bifurcation
Occasionally steep angled iliac bifurcations as encountered in Figure 3 may present a challenge to access, which may be further complicated by tortuous or calcified vessels. The fundamental challenge in these cases will be to direct a wire over the bifurcation and into the opposite iliac artery, over which a sheath can be advanced for contralateral limb interventions. The techniques entailed may include using a Cobra shaped catheter or a reverse curve catheter (Sos shape, Simmons etc) and then advancing a wire that is steerable and with adequate body to allow for sheath placement. One may even consider using a stiffer wire platform such as an amplatz guidewire or even a Lunderquist as they will straighten the aortic bifurcation curve after advancing a regular hydrophilic glidewire down to the contralateral groin or leg and then exchanging for the stiffer wire via a 4 French glidecatheter or crossing catheter. If the sheath still does not track over the bifurcation other alternatives would include using a longer dilator to allow for a smoother crossover transition (i.e. using the dilator from a 70 cm sheath in a 45 cm sheath) as illustrated in Figure 4. Another consideration is to inflate a 4 or 5 mm semi-compliant balloon and subsequently advancing the sheath over the balloon as it is deflated (this technique is illustrated in Figure 5). Alternatively a torqueable sheath such as the Tourguide (Aptus/Medtronic), Morph (BioCardia), or Destino (Oscor) would also be reasonable alternatives. A newer innovative solution is utilization of a Magellan robotic catheter (Hansen Medical) (Figure 6) which allows for multidirectional control of the intravascular catheter as well as unparalleled stability. Figure 8 and 9 demonstrate the use of a Magellan robotic catheter in navigating up and over a steep bifurcation to deploy an occlusion device in a contralateral hypogastric artery. A last option to consider for delivering large crossover sheaths is to snare the sheath over the aortic bifurcation via the contralateral femoral artery and thus provide a rail on which most any sheath should track
For tortuous iliac arteries it also may be difficult to track sheaths over, and in these instances it is important to get a long braided up and over sheath of adequate size to deliver the endovascular devices, as demonstrated in Figure 7.
Figure 4: Illustration demonstrating progressive advancement of a sheath over dilator for improved stability when crossing difficult aortic bifurcations. A) sheath and dilator approaching steep bifurcation. B) dilator advanced over a wire over the steep bifurcation. C) Sheath advanced across the steep bifurcation over the dilator and wire. (Illustration by: C.Molloy)
Figure 5: Illustration demonstrates advancing the sheath over balloon for improved stability when crossing difficult aortic bifurcations. A) Sheath approaching steep bifurcation with inflated balloon for improved stability. B) The sheath is advanced over the partially deflated balloon to navigate the steep aortic bifurcation. (Illustration by: C.Molloy)
Figure 6: Magellan Robotic Catheter (Hansen Medical) indicated by the blue arrow, covered in sterile plastic
Figure 7A: Catheterization up and over the aortoiliac bifurcation demonstrating extreme vessel tortuosity of the left common iliac, extending into the right external iliac, use of through and through access with angled glide catheter and glidewire to navigate the tortuousity
Figure 7B:16 French sheath up and over, through and through access with stiff buddy wire from contralateral left common iliac to the right external iliac. In non-calcified vessels, large bore sheaths can be used to track up and over the aortic bifurcation.
Figure 7C: Completed deployment of stent extension limb into internal iliac for hypogastric artery preservation
Figure 7D: Completion angiogram with 16 French sheath at the level of the aortic bifurcation
Figure 8: A) Aortogram demonstrates steep aortic bifurcation. This was technically difficult to navigate with manual catheterization. B) The 9 French Magellan robotic system (Hansen Medical) was utilized to cross up and over the aortic bifurcation and select the contralateral hypogastric artery. C) Hypogastric angiogram was performed from the 6 Fr Leader catheter of the robotic system.
Figure 9: A) Magnified angiogram of the right hypogastric artery performed via the Magellan robotic catheter. B) An 8 mm Amplatzer 4 device (St.Jude Medical) was deployed through the 6 French Leader catheter of the robotic system. C) The Amplatzer 4 device (St.Jude Medical) was successfully deployed. D) Post embolization angiogram demonstrates successful occlusion of the hypogastric artery at its origin.
When the ipsilateral and contralateral CFA access is simply not an option, several other alternative access sites throughout the lower and upper extremity vasculature may be viable options. Although there may be multiple alternative sites which may be utilized for vascular access, each site carries unique risks which must be considered prior to establishing access. Because each of these vessels are smaller than the CFAs and may present with more variable anatomy, ultrasound evaluation is recommended. Superficial Femoral Artery (SFA) Access Sometimes it is difficult to access the common femoral artery due to excessive obesity, scarred or hostile groin or very high riding femoral artery bifurcation. In these cases an alternative is to use the SFA for arterial access in a retrograde or antegrade fashion as demonstrated in Figure 10. Antegrade access via the superficial femoral artery (SFA) has been demonstrated as a safe access site for treatment of peripheral vascular disease.2,3,4 The SFA may be accessed with either 19g or 21g micropuncture needle with no significant difference in complication rates.5 In the setting of scarred groins, obesity or failed CFA access, some studies demonstrated that antegrade SFA access can have more favorable outcomes when compared with traditional CFA access.6 The main consideration when accessing from the SFA is the presence of variable anatomy, however ultrasound guidance of SFA access is commonly very successful. It is important to bluntly dissect the tissue to prep access and facilitate closure device use. Additional consideration for SFA access (or any site distal to the SFA) is the presence of a smaller vessel lumen which will limit the size of devices used. The rate of pseudoaneurysm formation may be higher with SFA access compared to common femoral access. Also, sometimes the interventionalist will face an occluded SFA stent that is impossible to cross from above or even via a pedal or popliteal approach. In these instances it may be reasonable to directly puncture the SFA stent using fluoroscopic and ultrasound guidance. It is best to try to minimize the access size by using a 20 gauge chiba needle or micropuncture needle and 018 wire system. Then once the stent is traversed the wire can be snared from a contralateral or antegrade CFA access. At this point we can advance the sheath into the SFA stent and proceed to recanalizing the stent. At this point once flow is demonstrated you can pull back the 018 wire out and perform angiography to exclude any significant extravasation. If there is significant extravasation you can usually control this with prolonged balloon inflation or even use a covered stent to plug the hole.
Figure 10: A) Axial CT demonstrating a high bifurcation of the Left CFA(blue arrow) in a patient with a ruptured left common iliac aneurysm (which is not shown). B) CO2 angiogram with percutaneous access directly into the left SFA with an 18 French sheath. C) Completion CO2 angiogram via direct SFA access. Popliteal Artery (PA) Access Both antegrade and retrograde access via the popliteal artery (PA) have been demonstrated to be safe.7,8 Early popliteal access implemented prone positioning9 (as demonstrated in Figure 11), which some patients were not able to tolerate. Fortunately, with evolving techniques patients may remain supine with their leg in external rotation with slight flexion (demonstrated in Figure 12) to gain medial access to the PA.10 Ultrasound access is highly recommended to visualize path directly into popliteal artery as well as to avoid the overlying popliteal vein. A 6 French 25cm long sheath may be used for antegrade access and a 45 cm introducer sheath may be used for retrograde access.11 In addition, due to the smaller caliber of the popliteal artery, one could consider using a micropuncture needle and 018 wire system to gain access via the popliteal artery and then utilize a contralateral access or antegrade common femoral artery access to snare the wire and then use the common femoral artery access to introduce devices for peripheral arterial interventions which may reduce the potential bleeding complications.
Figure 11: Right popliteal access with the patient in a prone position using a 6 French sheath.
Figure 12: Right popliteal access with the patient in a “frog leg” position with external hip rotation and slight knee flexion using a 6 French sheath. Pedal Access In lower extremity arterial revascularization it has been noted that sometimes an occlusive cap is easier to traverse from the distal aspect. It is feasible using a combination of ultrasound and fluoroscopy to access all 3 tibial vessels and the pedal arteries. Retrograde pedal access is demonstrated in Figures 13 and 14. Many operators are using low profile systems to revascularize the tibial circulation with balloon angioplasty or adjunctive techniques such as orbital atherectomy or laser atherectomy from a purely pedal approach. Most operators prefer to use a snare catheter or guidecatheter to externalize the pedal wire from an antegrade common femoral artery or superficial femoral artery access.
Figure 13: Retrograde pedal access with placement of a pedal micropuncture and 4 French sheath (Cook Medical). Pedal access may be achieved with either ultrasound or fluoroscopic guidance. Although the former is preferred, in patients with significant calcific disease, fluoroscopic guidance is utilized.
Figure 14A: Retrograde pedal access in a patient with necrotic toes. Recanalization of an occluded popliteal artery and anterior tibial artery had failed from an antegrade femoral approach and therefore the dorsalis pedis was accessed with a micropuncture needle with ultrasound guidance.
Figure 14B: Fluoroscopic spot image demonstrates successful wire advancement into the anterior tibial artery. Aortic access: With the increasing utilization of endovascular aneurysm repair the interventional community are identifying more type 2 endoleaks with aneurysm sac enlargement. These may not be amenable to access via a trans-arterial route or may not be easily identifiable even on conventional angiography. Another method of gaining access to these challenging endoleaks is with direct aortic sac entrance via a translumbar route. Some operators use fluoroscopy and anatomic landmarks as their initial guide. We feel it is safer to access these percutaneously under CT guidance from a posterior approach using 20 cm sheath needles (as demonstrated in Figure 15) and then once arterial blood is confirmed (Figure 16), taking them to the interventional suite for completion of the aneurysm embolization as demonstrated in Figure 17. Alternatively, cone beam CT guidance tools can be extremely valuable in this setting and can allow for direct access into the aortic sac without having to move the patient. Under fluoroscopy an 035 guidewire and a 5 French 25 cm vascular sheath may be placed, through which one can place 5 French catheters and navigate the aortic sac and deliver large diameter coils and liquid embolic material as well. Another approach is to deliver a microcatheter directly through the sheath needle and this avoids having to upsize the access. Another approach to access the aortic sac is via a transcatheter transcaval approach in which venous access is achieved via the femoral vein or internal jugular veins. It is important to evaluate the preprocedural imaging to ensure there is adherence of the IVC to the aortic wall. A 10 Fr, 40 cm reinforced angled sheath similar to that used for TIPS procedures is directed towards the aorta and a small amount of contrast is administered to ensure the sheath is wedged. A Colapinto needle (Cook Medical) is then directed into the aorta using fluoroscopic and/or intravascular ultrasound guidance. This approach is used for both treatment of type II endoleaks as well as performing aortic procedures requiring large sheaths in patients who have significant iliac disease which would preclude placement of a large caliber sheath. For the latter indication, electrocautery attached to a guidewire (i.e. Confianza, Abbott Medical) has also been utilized to traverse the caval wall and enter the aorta. At the completion of the procedure, the aorto-caval connection may be closed with a VSD occluder (St Jude Medical) to prevent a fistula.
Figure 15: Axial CT images demonstrating direct percutaneous aortic aneurysm sac access A) A percutaneous 5 French sheath needle tip entering the psoas muscle. B) The percutaneous needle tip is entering the aneurysm sac. C) The percutaneous needle tip has entered the aortic aneurysm sac.
Figure 16: Direct percutaneous aneurysm sac access with sheath needle demonstrating arterial blood return
Figure 17: Image series demonstrating direct percutaneous aortic aneurysm sac access and coil embolization of a type II endoleak. A) 5 Fr vascular sheath with 5 Fr angled braided catheter. B) Introduction of coils into the aortic aneurysm sac. C) Completion image demonstrating coils within the aortic aneurysm sac.
Radial Access Radial Artery access has traditionally been used for coronary interventions. Many interventional groups are utilizing this as a primary route for vascular interventions as there are fewer complications then a brachial route as well as improved patient satisfaction and comfort. It is critical to perform an Allen‟s test or Barbeau test prior to accessing the radial artery to prevent hand ischemia. A Barbeau D waveform is an absolute contraindication to radial access. At the end of the procedure it is critical to achieve hemostasis while maintaining hand perfusion . There are several proprietary devices used to maintain patent hemostasis. There are a few key things to sort out when doing radial artery interventions including using adequate vasodilators. Some prep the radial artery with EMLA and nitropaste prior to puncture. Some use an angiocath (doublewall technique) to go through and through the artery and then advance the microwire and then advance a lower profile sheath. Others use a micropuncture needle to access the artery and then after gaining access will give a cocktail of 200 micrograms of nitroglycerine, 2.5 mg of verapamil, and 3000 units of heparin (as demonstrated in Figure 18). An important technical point is to aspirate blood into the drug cocktail described prior to injection because the verapamil can be painful if not diluted. Utilization of hydrophilic sheath is mandatory. At the current time, the primary limitation of radial access for lower extremity interventions is the lack of endovascular tools of sufficient length. The iliac artery, common femoral artery, and proximal SFA may be treated with current technology. Upon conclusion of the procedure, hemostasis may be optimized by the use of a TR band (Terumo) which provides dual compression balloons which compress the radial artery, while sparing the nerves and simultaneously allowing for visualization of the access site to ensure hemostasis is achieved (as shown in Figure 19).
Figure 18: Radial artery access with aspiration of blood into drug cocktail consisting of 2.5 mg of verapamil, 200 mcg nitroglycerin, and 3000 units of heparin prior to injection. It is important to dilute the drugs with the patient‟s own blood prior to injection because verapamil injection can be painful otherwise.
Figure 19: Radial artery access with placement of TR band (Terumo) for patent hemostasis. The TR band is has dual compression balloons to provide compression of the radial artery without compressing the nerves. The transparent nature of device is designed to allow for visualization of the access site to ensure hemostasis is achieved.
Summary: In the past 50 years since Charles Dotter invented vascular interventions, we have come a long way with the concept of “surgery without a scalpel”. In order to overcome more and more challenging anatomy we have had to identify unique avenues to gain vascular access. We hope that this chapter will give you some practical pearls and allow you to treat some of the more complex vascular anatomies and vascular conditions that you may face.
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