Читать книгу Interventional Cardiology - Группа авторов - Страница 51

The basic technique of arterial access has changed very little since it was initially introduced by Seldinger [10]. Puncture of the common femoral artery is basically unchanged, save that the original concept used a through and through puncture and withdrawal of needle into the arterial lumen, while our current approach ideally punctures only the anterior surface of the femoral artery.

However, the technique can be substantially improved by using fluoroscopy of bony landmarks to identify the likely course of the common femoral artery followed by confirmation with femoral angiography after sheath insertion [11]. A point of entry into the common femoral artery at the mid femoral head or slightly above is ideal. The femoral skin crease, which is a very commonly used landmark for puncture, is distal to the common femoral bifurcation in 72% of cases [12]. Generally speaking, younger patients have a mid‐femoral head location relatively close or slightly above the femoral crease. Older patients have a femoral head significantly above the femoral crease, since the crease tends to sag with age. Obese patients may have two or sometimes even three femoral creases.

The technique of puncture requires multiple small steps to be optimized. Before local anesthesia is given, a clamp or needle can be laid at the point where the pulse is most easily felt, just above the femoral crease. Fluoroscopy can be used to locate the position of the needle relative to the center of the femoral head (Figure 2.3). Local anesthesia can thus be given accordingly. The needle should be aimed towards the artery at an angle of approximately 45^o, avoiding too vertical or acute angles between the needle and the skin plane that can create too vertical or too long paths within the subcutaneous tissue complicating large bore sheath insertion and subsequent closure. After local anesthesia is given, the needle is advanced in the direction of the artery using palpation as a guide. At this point, it is useful to fluoroscope the location of the needle once again. This is the last chance to adjust the puncture to enter the common femoral artery in the ideal landing zone. This method is not often adhered to, but in the long run is very worthwhile and justifies the few seconds of extra time at the beginning of the procedure. Meanwhile, this is also the time to observe the behavior of the needle that is placed close to the femoral artery. If the needle is moving up and down, it is indirect evidence of puncturing the anterior wall of the common femoral artery. However, if the needle is moving side to side, it is indirect evidence of puncturing the lateral or medial side of the common femoral artery. Small adjustments of the angle of attack to the femoral artery are possible but an overzealous needle direction adjustment may result in a tortuous skin track. If the operator realizes that the direction towards the artery is grossly inaccurate, we suggest to restart from the skin level instead of having later to deal with resistance to the introduction of sheaths and closure devices due to the pinched subcutaneous tissue. Especially in obese patients the risk of wire kinking is not negligible. A smaller (4 or 5 Fr) short sheath can be used first advancing a catheter up to the aortic arch over a conventional soft wire, switching at that point to a stiff wire for a safer advancement 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.