Basic Tools and Techniques for Brachio-Cephalic Arterial Intervention

Endovascular Techniques

Submitted on Fri, 09/18/2009 - 10:07
Authors

Frank J. Criado, MD, FACS, FSVM

Endovascular intervention has become the most common treatment modality for management of supra-aortic trunk (SAT) brachio-cephalic arterial occlusive disease.1–4 This is particularly so for patients presenting with stenosis (not total occlusion) affecting a single SAT vessel. While extra-thoracic, cervical-bypass, and transposition operations continue to be favored by many surgeons, they are increasingly reserved for patients who present with more advanced and extensive lesions, including recurrent restenoses following one or more prior endovascular procedures. Intra-thoracic surgical reconstructions, on the other hand, continue to have a significant — albeit diminished — role for cases with complex disease and multi-vessel SAT involvement.5 Percutaneous catheter-based intervention is now the preferred strategy for the vast majority of patients presenting with SAT disease and appropriate clinical indications for revascularization (Table 1). The techniques and equipment have evolved over the past 15 years. These procedures can be difficult to perform and are not without potential pitfall and complications. Case selection and technical strategies have a major impact. This technical article will focus on a description of the essential tools and techniques that have been found most useful in the author’s personal experience of nearly 20 years with endovascular treatment in the SAT brachio-cephalic arterial territory. Assessment of Aortic Arch Anatomy Assessment of SAT disease is most often obtained first using noninvasive imaging modalities such as magnetic resonance angiography (MRA) or computed tomographic angiography (CTA). Although these studies are valuable for initial diagnosis, conventional arch and selective angiography continue to have an important role at the time of definitive diagnosis and procedure planning. Seasoned interventional skills and a thorough understanding of the proper techniques of angiography are prerequisites for safe and successful SAT intervention. Use of a power injector is mandatory. A typical contrast injection rate would be 15–20 ml per second, for a total volume of 30 ml (“15 x 30”). With the angiographic catheter positioned proximal to the innominate artery origin (in the ascending aorta), a 30–45 degree left anterior oblique (LAO) projection will “open up” the arch and display aortic and SAT anatomy clearly and unencumbered. Cranio-caudal views may be necessary to visualize tortuous anatomy when the SAT take-offs may be obscured by the greater curvature of the arch. These are the so-called “compound views.” In the LAO view, the right subclavian artery (RSA) and right common carotid artery (RCCA) origins overlap, so a lesion in one of these vessels may be obscured by the other. Selective catheterization of the innominate artery and a right anterior oblique (RAO) projection are often necessary for optimal visualization of the right subclavian-right carotid bifurcation. Cranial tilting may be necessary as well. Catheterizing the Arch Branches This constitutes a most important step in every brachio-cephalic arterial intervention. The wide variety of available choices makes catheter selection quite difficult. First and foremost, the interventionist should strive to become familiar with a few catheters that he/she can use in most cases. Generally, I prefer simple-shaped (single-curve) catheters (vertebral, H-1, JB-1, JR-4, Berenstein, etc.) that tend to be user-friendly and effective in the majority of instances. Complex reverse-curve (double-curve) catheters (Simmons, Vitek, and others) are more difficult to use as they require reforming within the aorta. Such maneuvers carry potential for complications, including cerebral embolization and vessel wall injury. For such reasons, I favor use of the simpler vertebral or JB-1 and JB-2 catheters whenever possible (Figure 1). Interventions in the Left Subclavian Artery (LSA) The procedure begins with placement of a 5-Fr sheath in the femoral artery using standard catheterization technique. Following arch angiography, the LSA is selected using a vertebral (or similar) catheter, with subsequent passage of an angled 0.035 Glidewire (Terumo Corporation, Somerset, New Jersey) that is advanced across the stenosis and into the axillary artery. Next, a straight catheter is passed over the Glidewire and used in exchange for a stiffer (but soft-tip and steerable) guidewire — such as a Storq (Cordis Corporation, Miami Lakes, Florida) or Wholey (ACS, Mountain View, California) — that will support placement of a 90-cm long 6–7 Fr sheath that is advanced into the aortic arch to the origin of the LSA. It can –– at times –– be “parked” in the lumen of the proximal LSA itself when a sufficient length (“knob”) of normal vessel proximal to the lesion is present (Figure 2). Treatment of the target lesion is rather straightforward. Predilatation with an undersized (5–6 mm) PTA balloon is performed first to test the response to balloon inflation and size the vessel. The operator must then decide whether to use a self-expanding (Sx) or balloon-expandable (Bx) stent. We prefer the former in almost all situations today, with the exception of very short, truly ostial lesions — an unusual occurrence in our SAT experience. Precise vessel sizing for appropriate device selection is very important, especially when using Bx devices, as excessive oversizing can be dangerous. Sx nitinol stents, on the other hand, allow for more latitude in sizing, as the devices can (and should) be oversized by 1–2 mm (and even more on occasion). Proximity to the origin of the vertebral artery (VA) must be carefully evaluated. Angioplasty-related plaque disruption — rather than mere stent coverage — can cause dissection or occlusion of the VA origin. Gentle balloon dilatation of lesions in its proximity, balloon undersizing, and even preliminary selective catheterization of the vessel (with placement of an “indewelling” 0.014-inch coronary guidewire) are among available maneuvers for “VA protection” (Figures 3 and 4). The retrograde transbrachial approach is a useful technique for LSA intervention, especially valuable for endovascular treatment of total occlusions that tend to be resistant to antegrade recanalization. The brachial artery can be easily and safely accessed (in the antecubital fossa) using a micropuncture (21 g) technique. Placement of a 35 cm (or longer) 5–6 Fr sheath — to a point just below the distal extent of the LSA lesion — facilitates the procedure enormously. Retrograde recanalization is likely to require use of the Glidewire when a total occlusion is present. Re-entry of the true lumen in the proximal LSA or at the vessel origin in the aortic arch is paramount — to be verified by either intravascular ultrasound (IVUS) or contrast injection through a catheter passed back into the aortic lumen over the wire. A transfemoral diagnostic pigtail catheter is very useful as well, providing the ability to perform antegrade arch and retrograde subclavian angiographic injections. The technical steps that follow successful wire recanalization are much the same as those described above for the more standard antegrade approach. Approaches for the Proximal Left Common Carotid Artery (LCCA) Access options for the treatment of lesions in the LCCA include the antegrade femoral (preferred) and retrograde cervical (both open and percutaneous). We prefer the femoral approach for the majority of such patients. The cervical approach may be useful in patients with very tight stenotic lesions without the presence of a patent “knob” at the take-off from the aortic arch, as well as in cases of extreme arch and carotid tortuosity precluding antegrade access. The above-described transfemoral approach for LSA intervention can be used for the LCCA as well. Achieving stable access after successful selection by an angiographic catheter can be difficult, especially in type B and C arch anatomies, and when the LCCA originates from the innominate artery (“bovine anatomy”). In such cases, one of the following options may be used: • Buddy wire: a second stiff wire (0.035 or 0.018 inch) is placed alongside the interventional wire to straighten the tortuosity. The tips of both wires may be parked in the same vessel, typically a branch of the external carotid artery. The access sheath will need to be upsized (by 1 Fr size) to accommodate both the buddy wire and the selected stent (Figure 5); • Guide catheter: a pre-shaped guide catheter that conforms to the anatomy of the arch may be more stable than a straight sheath. Configurations that we find most useful in this location are the AL1 and H1. It is important to keep in mind that, unlike sheaths, guide catheters are sized by their outer (not inner) diameter; • Sheathless approach: Bilateral femoral punctures are performed. One access site is used for the diagnostic pigtail catheter, whereas the other is reserved for crossing and treating the lesion. In this way, repeat angiography can be performed via the diagnostic catheter instead of the sideport of the sheath (Figure 6). It is very important to pre-dilate the stenotic lesion in order to avoid stent dislodgement of the balloon during crossing. Alternatively, use of an Sx stent may avoid such a pitfall altogether. The retrograde cervical approach, both open and percutaneous, has been described previously.1 This approach is used only infrequently at present, but may be considered for the following: • Extremely tortuous arch anatomy; • Aorto-iliac-femoral occlusive disease precluding antegrade femoral access; • Near-occlusive lesions with no clear funnel or knob at the take-off from the aorta; • Treatment of tandem CCA and bifurcation stenoses (during carotid endarterectomy); • After a failed femoral approach. There is currently no consensus on the need for using cerebral protection during CCA interventions. Although the embolic potential appears to be low or very low, it would be logical to think that distal filters would further enhance the safety of such procedures. This may be particularly important in cases of external carotid occlusion where the ICA represents the only possible outflow bed for emboli. Unfortunately, devices suitable for CCA deployment are not currently available. And although ICA filters may be usable in such a scenario, they may not offer sufficient wire support for catheter and device delivery across angulated arch origins and the like. To that end, adjunctive maneuvers and use of buddy wires may be necessary (Figure 7). The innominate artery (IA). Intervention for IA stenosis can be difficult and fraught with danger. The risk is closely related to vessel anatomy. Large diameter (> 10 mm) and short length (From Union Memorial Hospital/MedStar Health, Baltimore, Maryland. Address for correspondence: Frank J. Criado, MD, Union Memorial Hospital/Medstar Health, 3333 North Calvert Street, Suite 570, Baltimore, MD 21218. E-mail: Frank.Criado@medstar.net. Disclosure: The author discloses that he is a member of the speakers bureau for Medtronic and is a consultant to Terumo Medical and Metronic Vascular.