Optimal Femoral Access Prevents Complications
Fifty-five years after the introduction of the Seldinger technique, there is demand for reassessment of femoral access and argument for routine femoral angiography.
Percutaneous femoral access has changed relatively little in the more than half century since Sven Seldinger liberated invasive cardiologists and radiologists from having to perform cutdowns.1 In general, however, vascular access has missed the invasive vascular revolution that has taken place in the subsequent 55 years. The original technique has been modified to avoid backwall puncture. The introduction of arterial sheaths in 19792 eliminated multiple transcutaneous catheter exchanges, a process that was associated with some morbidity. Extrapol-ating from the estimates of annual procedure volumes, several hundred million femoral artery access procedures have been performed worldwide. Despite the ever more sophisticated cardiac and endovascular procedures, femoral access remains the single greatest cause of complications.3
A survey of invasive radiologists and cardiologists conducted in England in 19904 revealed three primary techniques for access (Figure 1): the inguinal crease, the point of maximal pulsation, or the bony landmarks (typically a line drawn from the anterior superior iliac crest to the symphysis pubis). A minority of angiographers use a combination of these approaches. The survey found that the most common single technique (40%) involves using the inguinal crease alone. This is unfortunate because an important misconception exists in the literature—that the inguinal crease overlies the center of the femoral head. In fact, the typical location is below the femoral head, and equally important, below the femoral bifurcation (Figure 2).
LOCATION OF FEMORAL PUNCTURE
There is compelling evidence that vascular complications are related to the location of femoral puncture. High sticks correlate strongly with retroperitoneal hemorrhage, and low sticks with pseudoaneurysms, hematomas, and arteriovenous (AV) fistulae. The inferior epigastric artery (IEA), which originates above the inguinal ligament, initially descends but does not cross through the ligament. The lowest point in its sweep provides a best estimate for the path taken by the ligament (Figure 3). Punctures above this point have been associated with odds ratios for retroperitoneal hemorrhage as high as 17:1.5 In our series of quantitative femoral angiograms, this inferior sweep of the IEA rarely descends significantly below the centerline of the femoral head. Thus, avoidance of puncture above the femoral head centerline is an essential element in minimizing complications. Because retroperitoneal hemorrhage remains a cause of vascular access-related mortality, puncture below the centerline is probably the single most important safety recommendation among those listed in Table 1. It is important to point out that punctures below the inguinal ligament do not preclude extravasation of blood through the ligament and into the retroperitoneal space, and other factors, such as penetration of the needle during femoral puncture through the posterior wall of the artery, likely predispose to retroperitoneal hemorrhage as well.
There are two reasons why low punctures are associated with complications. First, puncture into the femoral bifurcation vessels (the superficial femoral [SFA] or profunda femoris [PFA] arteries) results in sheath placement into smaller blood vessels than the common femoral artery (CFA). For example, a 6-F sheath has an approximate 2.7-mm outside diameter and takes up nearly three fourths of the CFA lumen in many diabetic women (Figure 4). The bifurcation vessels are typically 1 mm smaller than the CFA, so the possibility of at least partial obstruction is significantly increased with puncture into the bifurcation vessels. In addition, patients with peripheral vascular disease are most likely to have SFA disease. Although the PFA is less commonly affected, in patients with total SFA occlusion, any disruption of the PFA intima and subsequent progression of disease in this vessel can eventually jeopardize leg viability.
Low punctures are not necessarily just those below the femoral head. Although we believe puncture below the centerline of the femoral head helps prevent retroperitoneal hemorrhage, progressively lower puncture over the femoral head results in increasing risk of bifurcation access. We have defined femoral bifurcation types as type 1 (bifurcation at or below the bottom of the femoral head, as in Figure 3A) and type 2 (bifurcation above the bottom of the femoral head). Type 2 bifurcations occur in approximately 25% of patients.6
A second source of morbidity from low sticks relates to puncture below the femoral head, whether or not it is into the CFA or a bifurcation vessel. The femoral head can be considered an anvil. During manual compression, if the puncture is below the femoral head, pressure is applied primarily against soft tissue, which is less effective, and complete hemostasis is less likely to be achieved, resulting in a predisposition to hematoma and pseudoaneurysm formation. Finally, femoral venous branches may course along and anterior to the bifurcation vessels, predisposing to AV fistulae.
Because the location of the IEA and femoral bifurcation are not known before puncture, the operator needs to consider puncture not only below the femoral head centerline, but also relatively high within the lower inner quadrant (the CFA is almost invariably medial) of the femoral head. The optimal location as we see it is shown in Figure 3.
THE CASE FOR ROUTINE FEMORAL ANGIOGRAPHY
A corollary to optimal access to prevent complications is the importance of ascertaining the location of the sheath entry with relationship to the IEA and femoral bifurcation. This can only be accomplished by routinely performing angiography through the sheath. We advocate performing the angiography as soon as access is achieved and, in all cases, before administering anticoagulation. Although performing femoral angiography before vascular closure device use has become the standard of care in the US (although it remains uncommon in the rest of the world), it is rarely performed by operators if manual compression is planned. Even when angiography is performed, it is predominantly done at the end of the case.
There are several important arguments for routine femoral angiography in all patients. First, femoral puncture is a procedure with significant associated morbidity, the success of which and the likelihood for associated complications cannot be assessed without angiography. Angiography provides information not just about puncture location but also about vessel size and presence of atherosclerotic disease, all of which have been shown to correlate with vascular complications. In addition, occasional incidental findings include dissection, extraluminal course of sheath entry, contrast extravasation, AV fistulae, and inadvertent puncture or transection of the inferior epigastric or circumflex hip arteries.
Second, in patients who have planned interventional procedures, or in whom ad hoc angioplasty is performed, ascertaining that the puncture is outside the CFA can prevent major complications if, based on the information obtained from the angiogram, anticoagulation is avoided. Retroperitoneal hemorrhage correlates not only with high sticks but also with anticoagulation: even with glycoprotein IIb/IIIa inhibitors on board, the incidence of retroperitoneal hemorrhage is <0.2% when anticoagulation is allowed to wear off before sheath removal.
TOWARD FEWER COMPLICATIONS
Vascular complication rates have declined steadily in the past decade, particularly in the interventional setting. A list of possible causative factors of vascular complications is found in Table 2. Cardiologists have been slow to adapt the techniques advocated in this article, and the evidence that either optimizing puncture location or routinely performing femoral angiography has improved outcomes is anecdotal. I do believe that following the steps listed in Table 1 can decrease complication rates significantly, but this remains unproven by adequately designed or powered randomized trials.
Several techniques widely used by interventional radiologists should be considered by interventional cardiologists. These include use of ultrasound for vascular access, using portable equipment that allows visualization and guidance of needle passage from the skin surface into the artery. A second technique is the use of a micropuncture 21-gauge needle with a .018-inch guidewire instead of the standard 18-gauge needle with a .035-inch guidewire; use of the latter, which unfortunately represents nearly universal practice in femoral puncture (and a significant portion of my practice, as well) could be considered unnecessarily traumatic, especially if, as is frequently the case, there is unsuccessful entry into the artery or if the back wall is penetrated. Again, although intuitive, there is no evidence base to confirm the benefits of micropuncture. A simple technique that we use in our laboratory in patients undergoing repeat catheterization is to take advantage of having done routine femoral angiography on every patient for the past 6 years. We review the previous femoral angiograms to assess for bifurcation location and the presence of femoral artery disease. If the patient has a type 1 bifurcation, the longitudinal target zone for access increases substantially to cover most of the bottom half of the femoral head.
Although we are 55 years into the Seldinger technique, the much-delayed time has come for a thorough and scientific re-examination of our femoral access techniques. Radial access, a popular alternative in the rest of the world, remains uncommon in the US, and is limited to some degree by the size of the radial artery. With the advent of evermore creative invasive technologies, femoral access remains the route of choice for a host of complex procedures, including percutaneous heart valves, aortic stent graft placement, and ventricular assist devices, among others. These technologies require placement of large sheaths, frequently in patients with diseased femoral and iliac arteries and with multiple comorbidities. The use of an evidence-based approach to vascular access in these patients is an essential element in the safe expansion of cardiac intervention to a host of new therapies.
Zoltan G. Turi, MD, is Professor of Medicine, Robert Wood Johnson Medical School, in Camden, New Jersey. Dr. Turi may be reached at (856) 342-3488; email@example.com.