Choice of Puncture Site and Technical Aspects The inguinal crease is frequently used as a landmark, based on the belief that the level of the inguinal crease is closely related to the inguinal ligament.8,9 However, the distance between the inguinal crease and the inguinal ligament is highly variable, ranging from 0 to 11 cm (mean, 6.5 cm), and the bifurcation of the CFA is above the inguinal crease in 75.6% of patients.9 Another frequently used landmark, the maximal femoral pulse, is over the CFA in 92.7% of limbs, and the CFA is projected over the medial aspect of the femoral head in 77.9% of limbs. This indicates that the level of the strongest femoral pulse is a more reliable means of localizing the CFA than the level of the inguinal crease. Therefore, although popular, the use of the inguinal skin crease should be considered an unreliable guide for CFA puncture. The use of palpable landmarks based on the iliac crest and the pubic bone has been recommended as reliable guides to achieve CFA access: either the midpoint of a line drawn between the anterosuperior iliac spine and vertical midpoint of pubic symphysis or a point 2.5 cm distally along a line perpendicular to the line drawn between the anterosuperior iliac spine and the pubic bone can be used.6 The presence of clearly identifiable landmarks can be obscured by obesity, the presence of residual hematoma, or scar tissue from previous percutaneous or surgical interventions. Low blood pressure or the absence of pulse distal of a stenosis or occlusion of the iliac arteries can also be a problem when identifying a proper puncture site. In cases when there is an absence of a femoral pulse, the following technique has been described.10 Place a finger immediately lateral to the pubic tubercle and inferior to the inguinal ligament, with subsequent palpation of the point that allows the most posterior depression that anatomically lies between the iliopsoas muscle laterally and pectineus medially. The femoral vein can be found in this depression, and the CFA will be found 1.5 cm lateral to this point. Besides palpation, fluoroscopy has also been used in early interventional experiences as a landmark,11,12 with the CFA bifurcation occurring at or below the center of the femoral head in 98.5% of cases.3 The puncture entry site at the level of the skin should be made 1 to 2 cm caudal (in the case of retrograde puncture) or cranial (in case of antegrade puncture) to the planned arterial entry site. The site of skin entry should vary, according to the amount of subcutaneous fat. After skin penetration of the needle, and with the needle lying directly over the artery, fluoroscopy should be performed again. At this point, the needle should be left lying. By doing so, one can avoid radiation exposure of the hands of the operator. The disadvantage of the fluoroscopic method is the increase in radiation exposure for the patient (and, to a lesser extent, the operator).6 Use of fluoroscopy aimed at the level of the middle femoral head will lead to a puncture of the CFA (above the bifurcation) in 99% of cases, thus allowing both retrograde and antegrade access. By using this technique, no intraperitoneal punctures will occur. Needle entry into the artery should be roughly at the bottom of the upper inner quadrant of the femoral head (in an anteroposterior projection; Figure 2).13 Morbidly obese patients and patients with a lack of palpable femoral pulse are two categories of patients who might benefit most from fluoroscopically guided puncture.14 The incidence of pseudoaneurysms or any other arterial injury can be reduced with the use of fluoroscopy, but no difference in the occurrence of bleeding complications or an influence on the length of hospital stay can be seen.15 The third technique that can be adopted is ultrasoundguided puncture. With the use of ultrasound, the location of the CFA, femoral artery bifurcation, and inferior epigastric arteries can be readily identified, and thus inadvertent high or low puncture can be avoided (Figure 3). In addition, ultrasound is able to identify arterial wall disease (atherosclerotic plaque with or without calcification and mural thrombus) that cannot easily be identified with angiography, especially when performed in an anteroposterior projection. In this way, puncture of diseased areas or the sidewall can be avoided. This reduces the risk of puncture site complications, especially when arterial closure devices are being used. Real-time monitoring of needle advancement in the subcutaneous tract and intraluminal positioning of the needle tip can be confirmed, thus avoiding posterior wall puncture. It has been demonstrated that the incidence of pseudoaneurysm formation can be significantly reduced from 4.5% (in patients undergoing traditional palpation-guided vessel cannulation) to 2.6% when ultrasound guidance is used, mainly by avoiding inadvertent puncture of the external iliac artery and superficial and deep femoral artery.16 In a prospective evaluation of ultrasound-guided CFA puncture, it was found that the ultrasound-guided technique reduced the time to puncture and the number of attempts in obese patients and patients with weak or absent pulses.17 In a randomized study, it was found that routine real-time ultrasound guidance can improve cannulation in patients with a high CFA bifurcation and reduces the number of attempts, time to access, risk of inadvertent venous puncture, and vascular complications.18 By using either anatomical landmarks (palpation and fluoroscopy) or ultrasound, safe CFA access for both retrograde and antegrade procedures can be achieved, thereby reducing the complication rate and allowing for the safe use of closure devices.
Posted on: Thu, 11 Jul 2013 13:29:44 +0000
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