of larger sheaths.
Figure 2.3 (a) shows a fluoroscopic image recorded prior to puncture. The 18 G thin wall needle has been laid on the skin at the point of anticipated femoral puncture based on palpation. The arrow shows the tip of the needle. Fluoroscopy demonstrates that the needle is at the lower border of the femoral head. This is an ideal location for skin entry as the needle will puncture the femoral artery superior to this point. (b) shows the needle advanced until the pulsation of the femoral artery is felt to be transmitted through the needle. The arrow shows the position of the needle. This is just below the mid femoral head and is an ideal “landing zone” for puncture. The majority of patients’ femoral artery bifurcation will be below this point and the probability of common femoral artery entry is high. The arrowhead pointing upward shows the location of the skin crease. In (c) sheath angiography demonstrates that the entry point is in the common femoral artery above the line of the mid femoral head. This is higher than ideal but represents a good entry point for the sheath. Just above the sheath entry site, the U‐shaped branch of the external iliac artery denotes the location of the inguinal ligament and the division between the common femoral artery and the retroperitoneal iliac vessel. This branch is the deep circumflex iliac artery.
After arterial puncture and wire insertion, record a brief fluoroscopy with the needle still in place to memorize the exact location of the arterial puncture (Figure 2.4G). This might become handy in case of closure device failure with the need of covered stent placement at the exact location of the initial puncture.
Figure 2.4 (A) The ultrasound probe is aligned perpendicular to the artery (angle d), imaged here in longitudinal axis. The needle is inserted approximately at 45 degrees (angle a) at a distance (b, yellow dotted line) that takes into accounts the angles a and d as well as the depth of the artery (c, blue dotted line) and would normally be approximately 1–2 cm more caudally than the intended arterial entry site.). (B) In the longitudinal echographic view the common femoral artery (CFA) with its bifurcation is imaged, in the proximal aspect of the CFA the inguinal ligament is visualized as a triangular echo density (arrow heads), while by increasing the depth of the ultrasound image (C) the underlying femoral head (FH) is visible. (D) Femoral bifurcation imaged in the axial view. By slight cranial movement of the probe the common femoral artery is visualized and tackled by the needle by short jabbing movements until the needle artifact is shown as an indentation of the arterial wall (panel (E) – asterisk) immediately before the puncture. (F) The track of the angiographic wire inserted in the artery through the needle can be appreciated at ultrasound as well as on fluoroscopy (triangle) (G).
Once the sheath has been inserted, a sheath angiogram should be performed. Using an AP projection best preserves the relationship between the puncture site and the lower border of the inferior epigastric artery, but may have overlap of the femoral bifurcation. A 20° ipsilateral angulation of the image intensifier will expose the entry point of the sheath, as well as the femoral bifurcation [6].It can thus be determined whether the common femoral artery has in fact been entered, and whether there is atherosclerosis, calcification, or angulation of the puncture site. It is our practice to obtain the sheath angiogram at the beginning of the procedure, so that decisions about closure and sometimes anticoagulation can be made before the procedure is performed. If the sheath has been inserted into the branch vessels below the bifurcation, this will often have an impact on ultimate sheath size, for example in the setting of bifurcation or chronic total occlusion intervention, and can impact the choice of anticoagulation. When the puncture is above the most inferior border of the inferior epigastric artery, it is likely that the retroperitoneal space has been entered with the sheath. In this instance, an option is to defer intervention until a later time. Full anticoagulation with the sheath in this location greatly increases the risk of retroperitoneal bleeding, which is one of the worst and more difficult local complications to manage.
Ultrasound guided femoral access
Ultrasound guided vascular access has gained attention by catheterization laboratories for arterial access, especially for large bore vascular access. The main advantage of ultrasound guided access is to identify the anatomy of the vessels and the relationship between the artery and the vein. Ultrasound guided access helps to select the puncture site more precisely. By using a sterile plastic cover, a 5–10 Hz linear ultrasound probe is positioned over the point of maximal pulsation to scan the femoral artery and vein. Each probe has a reference marker which is a vertical line, often backlit, that should be aligned according to the patient’s topography (e.g. to the patient’s right while scanning the groin vessels in short axis). The probe should be placed over the point of maximal arterial pulsation to identify the vessel. The artery should be imaged in both longitudinal and axial view starting with an axial view where the femoral artery appears as a pulsatile circle. The artery has thicker arterial walls than the vein, often with calcium or plaques, and can be easily identified because of its pulsatility. If there is any doubt identification of femoral artery versus vein is easily achieved applying gentle pressure with the vascular probe. The artery is not compressible, and the pulsations become more apparent while the vein collapses. Note that pulsation of the vessels can be misleading in patients with severe tricuspid regurgitation. Calcification or plaques along the artery help selecting the optimal puncture point once, by cranial and/or caudal scanning, the femoral bifurcation is found. If the probe is now turned clockwise (for the right femoral artery) or counterclockwise (for the left femoral artery) by 90 ° with the probe marker pointing cranially, the longitudinal view of the artery is obtained. Here the femoral bifurcation is imaged, with relation to the underlying femoral head and, possibly, the inguinal ligament (visualized as an echodense triangular density cranially to the femoral head in the longitudinal view and as a linear density on axial views) (Figure 2.4).
Ultrasound is able to easily localize the femoral bifurcation, avoiding “low” punctures, but the superior limit of a correct puncture (inguinal ligament) is more difficult to identify, often leading to a “high puncture” (in up to 6.6% of the cases) [13]. Careful integration of the fluoroscopic and ultrasound information can minimize this risk. With the probe aligned perpendicular to the artery, imaged in the center of the view, the needle is inserted approximately at 45 °, 1–2 cm more caudally than the intended arterial entry site (center of the probe) (Figure 2.4). The artery is gently approached by repeated short jabbing movements. The needle will become visible when it enters the imaging plane of the probe. The probe can be slightly tilted to identify the reverberant artifact of the needle’s path to the artery but we recommend to use the same fixed probe angle to image the bifurcation of the common femoral artery to avoid high punctures, When the needle enters the artery insert the wire and use ultrasound again to accurately identify the puncture location. The rest of the procedure follows the standard procedure for vascular access. Sometimes, the vein runs medial and posterior to the artery. Using ultrasound can occasionally be useful to avoid entering artery before venous access and prevent other complications such as arteriovenous fistulae. In a multicenter randomized trial (FAUST trial) ultrasound as compared to fluoroscopic guidance increased common femoral artery cannulation in patients with high femoral bifurcation and improved first pass success rate, reduced the number of attempts, the risk of venipuncture and median time to access [14].
Hybrid access techniques such as integrating ultrasound with fluoroscopy or guidewire‐aided technique [15] can be helpful to obtain a correct puncture. The first technique involves
