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Address reprint requests to René Bombien, MD, PhD, Division of Cardiothoracic Surgery, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, SCCT 2S03, Los Angeles, CA 90048
The catheter-based treatment of valvular disease and aortic disease is emerging as an attractive alternative to treat high-risk patients. Compared to open surgery, large-bore catheter-based treatments offer less trauma, no heart-lung machine, shorter procedural times, and a significantly faster rehabilitation with acceptable short- and midterm results.
These large-bore catheter-based therapeutics require device-specific knowledge, along with procedural experience, most importantly involving vessels to gain access to the area of interest. In this article, we discuss the most common approaches used in endovascular aortic repair (EVAR), thoracic endovascular aortic repair (TEVAR), and transcatheter aortic valve replacement (TAVR) procedures: transfemoral (I), transapical (II), and the direct aortic approach (III). Alternative, less commonly used access sides such as the common carotid and the axillary artery site (IV) are outside of scope of this article.
Preoperative Evaluation
Protocolized and excellent quality computed tomographic angiogram or time-of-flight magnetic resonance imaging/magnetic resonance angiography are critical in the preoperative evaluation of the access vessels for EVAR/TEVAR and TAVR. The femoral artery offers an adequate conduit for large-bore devices in over 90% of cases. The surgeon will look for small, tortuous, or heavily calcified iliofemoral arteries. One or two of these obstacles may be managed using endovascular techniques. However, when dealing with all three aspects, this usually requires an alternative approach (such as serial dilatation, iliac conduit, and “endo-conduit”) or another access site. Although mild tortuosity of the iliac arteries is normal, severe tortuosity and completely straightened iliac arteries (consistent with calcific changes) are both red flags for perioperative access vessel complications.
For patients with “horizontal aorta” undergoing TAVR, the transapical approach will allow for more coaxial device deployment, making the transapical route the preferred approach. For direct aortic access, the amount of plaque burden in the ascending aorta must be carefully evaluated on the preoperative imaging.
Figure 4Femoral arterial access. One or both femoral arteries are chosen based on preoperative imaging. Usually the largest iliofemoral vessel is used for large-bore device introduction, and the contralateral side is used for imaging as well as contralateral limb (in patients undergoing EVAR). Unilateral femoral access for an angiography catheter is adequate in transapical TAVR and TEVAR procedures if additional brachial/radial access is established for angiographic purposes.
Percutaneous access to the femoral arteries may be obtained using ultrasound-guided puncture using a micropuncture set. An angiogram through the 0.018-inch compatible introducer excludes a high or low stick. This access is subsequently dilated to a 0.035-inch introducer. Subsequently, the track is dilated using an 8-Fr dilator, and 2 Proglide (Abbott Vascular, Abbott Laboratories, Abbott Park, IL) suture-mediated closure systems are deployed in preparation for larger bore access. This Perclose technique reduces postoperative pain and accelerates recovery; however, it is more expensive and associated with a significant rate of failure in inexperienced hands.
The common femoral artery is surgically exposed through an oblique incision, 1 to 2 cm lower to the inguinal ligament, immediately as it exits the abdominal wall. Then, under strict protection of the lymphatic nodes and their vessels to prevent a lymphatic fistula, the femoral artery will be exposed.
Figure 5The Seldinger technique. The puncture needle is inserted in an approximately 45° angle into the vessel (A). Once the starter wire is inserted using the Seldinger technique, the needle can be withdrawn (B). Then, a 5-Fr or 8-Fr sheath can be placed over the wire into the vessel to allow for further catheter guidance of the starter wire to the target area (C). Next, the starter wire will be exchanged with stiffer wire (D).
Significant tortuosity of the iliac artery can also be straightened by using a stiff wire to improve pushability of the device. If the diameter of iliofemoral vessel is ≤6 mm, it is recommended to sound the vessel using serial dilators (such as 14-Fr, 18-Fr, and 22-Fr). The technique is easy and effective, but must be performed with extreme caution to avoid perforation. The endoconduit is a more advanced approach, deploying a covered stent graft into the external and common iliac artery, and performing controlled rupture of the iliac artery using aggressive angioplasty. This effectively allows for device passage through the covered stent graft to the area of interest.
Figure 6The retroperitoneal approach. If the iliofemoral vessel is deemed too small, tortuous, and calcified for femoral arterial access, a retroperitoneal access should be considered (A). A Dacron graft (ie, 10 mm) serves as an iliac conduit and will be sewn to the distal common iliac artery, or to the distal abdominal aorta (B). a. = artery.
To make the entrance angle for the endovascular device smoother, the conduit is tunneled through the inguinal canal and diverted through the oblique femoral incision (C). The Dacron graft is clamped at the end and cannulated from the side for TEVAR/EVAR or TAVR entry. After the procedure, the woven conduit will serve as an iliacofemoral bypass in case of an occluded or stenosed external iliac artery and will be anastomosed to the common femoral artery in an end-to-end fashion.
Figure 6The retroperitoneal approach. If the iliofemoral vessel is deemed too small, tortuous, and calcified for femoral arterial access, a retroperitoneal access should be considered (A). A Dacron graft (ie, 10 mm) serves as an iliac conduit and will be sewn to the distal common iliac artery, or to the distal abdominal aorta (B). a. = artery.
To make the entrance angle for the endovascular device smoother, the conduit is tunneled through the inguinal canal and diverted through the oblique femoral incision (C). The Dacron graft is clamped at the end and cannulated from the side for TEVAR/EVAR or TAVR entry. After the procedure, the woven conduit will serve as an iliacofemoral bypass in case of an occluded or stenosed external iliac artery and will be anastomosed to the common femoral artery in an end-to-end fashion.
Figure 7Transapical access. The apex of the left ventricle offers excellent access because it forms a straight, uncalcified, and prominent entry to the diseased aortic valve and the thoracic vascular system and is mainly used for TAVR procedures (A). The structural damage to the cardiac muscle is minor with only limited hemodynamic compromise. However, it should be noted that patients with an apical ventricular aneurysm, or an apical intracardiac thrombus, should not be considered for the transapical access. Double-lumen intubation is usually not necessary for a transapical approach. The anatomical orientation is the fifth intercostal space in the anterolateral position on the left side (B, C), or fluoroscopic determination of the left ventricular apex. Ao = aorta; LV = left ventricle.
The incision should be directed onto the superior edge of the sixth rib, and the fifth intercostal space is entered without injury to the lung. Once the incision is complete, the moving left ventricular apex will become visible. The retractor must be placed with the screw thread to the left lateral side of the patient to allow for unobstructed radiographic beam during fluoroscopy and to reduce radiation (D). The next step is to prepare the pericardium to expose the apex. To achieve the optimal area for left ventricular access, the apex must be identified by palpation, echocardiography, and fluoroscopy. Pressing on the apex is usually clearly visible on the transesophageal echocardiogram. A micropuncture needle followed by a 0.018-inch wire is inserted in the apex under fluoroscopic guidance. The echo will confirm the proper position of the wire in relation to the septum. Subsequently, 2 purse-string sutures using 2-0 MH Prolene is placed in the apex using multiple pledgets (D, E). For TAVR procedures, the rapid pacing electrode may be added and tested. The exchange of wires and catheters are consistent with a transfemoral approach using the Seldinger technique (see Fig. 5). LAD = Left anterior descending.
Figure 7Transapical access. The apex of the left ventricle offers excellent access because it forms a straight, uncalcified, and prominent entry to the diseased aortic valve and the thoracic vascular system and is mainly used for TAVR procedures (A). The structural damage to the cardiac muscle is minor with only limited hemodynamic compromise. However, it should be noted that patients with an apical ventricular aneurysm, or an apical intracardiac thrombus, should not be considered for the transapical access. Double-lumen intubation is usually not necessary for a transapical approach. The anatomical orientation is the fifth intercostal space in the anterolateral position on the left side (B, C), or fluoroscopic determination of the left ventricular apex. Ao = aorta; LV = left ventricle.
The incision should be directed onto the superior edge of the sixth rib, and the fifth intercostal space is entered without injury to the lung. Once the incision is complete, the moving left ventricular apex will become visible. The retractor must be placed with the screw thread to the left lateral side of the patient to allow for unobstructed radiographic beam during fluoroscopy and to reduce radiation (D). The next step is to prepare the pericardium to expose the apex. To achieve the optimal area for left ventricular access, the apex must be identified by palpation, echocardiography, and fluoroscopy. Pressing on the apex is usually clearly visible on the transesophageal echocardiogram. A micropuncture needle followed by a 0.018-inch wire is inserted in the apex under fluoroscopic guidance. The echo will confirm the proper position of the wire in relation to the septum. Subsequently, 2 purse-string sutures using 2-0 MH Prolene is placed in the apex using multiple pledgets (D, E). For TAVR procedures, the rapid pacing electrode may be added and tested. The exchange of wires and catheters are consistent with a transfemoral approach using the Seldinger technique (see Fig. 5). LAD = Left anterior descending.
Figure 8Alternatives for TEVAR access: the transapical access and the direct aortic access. Indications for ascending aortic access are usually in patients with unsuitable iliofemoral vessels and poor candidates for transapical approach (such as severe chronic obstructive pulmonary disease, significant lung adhesions, apical aneurysm, etc.). This implantation method requires a right lateral thoracotomy or an upper sternotomy, partial or full, to gain access to the ascending aorta. A double purse-string suture will be placed along a suitable, uncalcified part of the aortic wall (see Fig. 3). Alternatively, a 10-mm Dacron graft may be sutured to the ascending aorta using a partial occluding clamp.
Subsequently the wires will be advanced under fluoroscopic guidance to the left ventricle for TAVR procedures and to the descending thoracic aorta for TEVAR procedures.
Vascular access injury is the most common complication in large-bore procedures including EVAR/TEVAR and TAVR with potentially fatal consequences. The incidence of injury to access vessels including dissection, rupture, fistula, hemorrhage, thrombosis, and pseudoaneurysm occurs in 1% to 15% of patients, complicating the procedure, ranging from claudication, severe limb ischemia, and need for bypass surgery to death.
Preoperative imaging will provide red flags for possible injury and indications for alternative access sites. An iliac artery rupture is usually suspected during a transfemoral procedure, when the iliac artery suddenly “gives away” (the pushing resistance is lost), or when there is an unexpected drop in blood pressure on removal of the large-bore sheath. In these instances, it is important to keep calm and manage the operative team resources wisely, by asking for blood products and appropriate covered stents, balloons, and surgical instruments to be brought in the room.
As soon as an iliac rupture is suspected, the large-bore sheath is reinserted in the ipsilateral position, controlling the blood loss with the tamponade effect. Most importantly, the guidewire must be kept in place throughout this critical portion of the operation. Next, a 12-Fr sheath is placed in the contralateral artery and a semicompliant balloon is expanded in the infrarenal aorta. A subsequent iliac angiogram through a pigtail catheter, after the sheath is gently withdrawn, will confirm the presence and location of the iliac artery injury. Although the contralateral balloon control of the infrarenal aorta is maintained, an appropriately sized covered stent graft is deployed over the guidewire to seal the injured vessel (Fig. 9). Open repair should be considered if the endovascular approach is not successful, or if the surgeon is not comfortable with the peripheral arterial stent grafting.
Figure 9The iliac artery rupture is managed with stent graft deployment excluding the injured area of the iliac artery.
The presented access methods offer a reproducible and safe approach to perform endovascular procedures. Access site selection and management are critical aspects of the large-bore device procedure: advantages of the femoral route include ease of access, faster recovery, and the possibility of using local or regional anesthesia instead of general anesthesia. However, the long distance from the iliofemoral vessels to the area of interest harbors a higher risk of vascular damage and embolic events, including neurovascular emboli when the large-bore device is passing through the aortic arch. The advantage of the direct aortic or transapical approach is the straight route, and being close to the target zone, making the device deployment more accurate. However, neither an anterolateral thoracotomy nor a median sternotomy can be performed under local anesthesia, and the patient recovery is prolonged.
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