A Prospective Randomized Clinical Trial of the Use of Fluoroscopy in Obtaining Femoral Arterial Access

From the Cardiac Catheterization Laboratory, University of North Carolina, Chapel Hill, North Carolina, and the ^*Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, Greenville, North Carolina. The authors report no financial relationships or conflicts of interest regarding the content herein. This study was funded by an unrestricted grant from St. Jude Medical. St. Jude Medical did not participate in any portion of the study design, implementation, or analysis. Manuscript submitted November 6, 2008, provisional acceptance given December 4, 2008, final version accepted December 30, 2008. Address for Correspondence: George A. Stouffer, MD, Division of Cardiology, University of North Carolina, Chapel Hill, NC 27599-7075. E-mail: rstouff@med.unc.edu

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ABSTRACT: Background. There is no consensus on the utility of fluoroscopy in obtaining common femoral artery (CFA) access. Methods. Patients weighing Results. 208 patients were enrolled with 110 randomized to the palpation group and 98 were randomized to the palpation + fluoroscopy group. Mean age (± SD) was 60 ± 11 years, 61% were male, 35% had diabetes, and 40% had a body mass index (BMI) > 30 kg/m². Clinical characteristics and procedural factors were similar among the two groups with the exception that fewer needle passes were required and access was achieved faster in the palpation group. Arterial puncture over the femoral head occurred in 91% of the palpation group versus 95% of the palpation + fluoroscopy group (p = 0.27). Successful CFA puncture occurred in 85% of the palpation group versus 90% of the palpation + fluoroscopy group (p = 0.49). Cannulation of the external iliac artery occurred in 1 patient in each group, whereas arterial puncture distal to the CFA bifurcation occurred in 16 (15%) of the palpation group and in 9 (9%) of the palpation + fluoroscopy group (p = 0.33). Conclusion. In this single-center, randomized trial, the use of fluoroscopy did not increase the probability of arterial puncture over the femoral head or the rate of successful CFA cannulation.

J INVASIVE CARDIOL 2009;21:105–109

Key words: femoral artery, fluoroscopy, vascular complications

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Vascular complications during cardiac catheterization and percutaneous coronary intervention (PCI) worsen outcomes and are associated with an increased risk of post-procedure myocardial infarction (MI) and death.^1,2 The majority of percutaneous procedures are performed from the leg and the incidence of access-site complications ranges from 1–10% depending on the definitions used and the patient population studied.^3–5 Successful cannulation of the common femoral artery (CFA), as opposed to access via other arteries in the inguinal region, is associated with a greatly reduced risk of vascular complications due to its size and compressibility.^6,7 The femoral head, visible with fluoroscopy, offers a reliable landmark for identifying the CFA. The bifurcation of the CFA is consistently below the center of the femoral head and caudal to the level of the inguinal ligament.^8,9 It therefore seems reasonable that fluoroscopy, using the middle of the femoral head as a landmark, would increase the rate of successful CFA punctures and in turn decrease the rate of femoral artery complications. But despite these theoretical benefits of fluoroscopy, there remains wide practice variation in the use of fluoroscopy to obtain arterial access. Reasons cited for not using fluoroscopy include the high rates of success with palpation alone, the additional time and radiation exposure associated with the use of fluoroscopy, and the lack of data regarding benefit. Since there has been no systematic study of the utility of fluoroscopy, we conducted a prospective, randomized trial comparing CFA cannulation in patients in whom arterial access was obtained utilizing palpation alone or palpation + fluoroscopy.

Methods

Patients and study protocol. The study population consisted of unselected, nonconsecutive patients who underwent cardiac catheterization at the University of North Carolina Memorial Hospital between June 2005 and August 2007. Recruitment to the study was limited to times when a research coordinator was available, which limited enrollment. The study protocol was approved by the institutional review board and all patients gave written informed consent prior to participation. Consenting adult male and female patients 18 years of age or older undergoing left-heart catheterization and/or coronary angiography via transfemoral arterial access at the University of North Carolina Hospitals were randomized to arterial puncture with palpation + fluoroscopy (using the mid-point between the upper and lower borders of the femoral head as the optimum site to enter the artery in the superior-inferior plane) versus arterial puncture using only femoral pulse palpation. Exclusion criteria included weight > 136.4 kg (300 lbs), serum creatinine > 2 mg/dl, lack of a palpable femoral pulse, concurrent venous access, or prior surgery on the femoral artery at the site of access. The sheath was removed using manual compression either at the end of the procedure (diagnostic catheterizations) or when the anticoagulant effect had resolved (PCI). Femoral angiograms in two views (anteroposterior and ipsilateral oblique) were obtained at the completion of the case and independently reviewed by two experienced operators blinded to randomization. Successful CFA puncture was defined as arterial puncture distal to the most inferior portion of the inferior epigastric artery and proximal to the origin of the profunda. Patients were defined as diabetic if receiving hypoglycemic medication. Patients were defined as having peripheral arterial disease (PAD) by the presence of claudication or documentation of atherosclerotic disease in the extremities. A hematoma was defined using the criteria of the American College of Cardiology – NCDR Cath PCI Registry.¹⁰ Informed consent was obtained from 227 patients, with 19 being excluded because a femoral angiogram was not obtained. The most common reason for not obtaining a femoral angiogram was because the operator did not want to expose the patient to additional contrast. Of the 19 patients not receiving femoral angiograms, 1 complication was reported consisting of a hematoma that did not require a blood transfusion. Statistical analysis. Sample size calculation assumed a rate of successful CFA punctures of 85 ± 6% based on published studies,^9,11,12 and thus 200 patients would be needed to have a statistical power of 80% to detect a mean difference of 12% in the rate of successful CFA punctures between the fluoroscopy and nonfluoroscopy groups, with a two-sided significance level of 5%. Continuous variables are presented as mean ± standard deviation. Categorical variables are presented as numbers and percentages. Differences in baseline and angiographic characteristics were compared using a Student’s t-test for normally distributed continuous variables and a Wilcoxon rank sum test for non-normally distributed continuous variables. Differences in baseline and angiographic categorical variables were compared using the chi-squared test or a Fisher’s exact test when appropriate. Differences were considered significant at a value of p (Stata Corp., College Station, Texas).

Results

The baseline characteristics of the 208 patients enrolled in the study included a mean age (± standard deviation) of 60 ± 11 years, 61% were male, 35% diabetic, 21% had peripheral arterial disease and 40% had a body mass index (BMI) > 30 kg/m2. Normal femoral pulses were present in 95% with the remainder having diminished, but palpable, pulses. In the vast majority of patients, access was obtained in the right groin (98%) using a 6 Fr sheath (97%) by a cardiology fellow (94%). Clinical characteristics and procedural factors were similar among the two groups, with the exception that fewer needle passes were required and access was achieved faster in the palpation group (Table 1). For analysis purposes, the femoral head area was divided into five zones. Zone 1 is the area superior to the femoral head, zones 2, 3 and 4 represent the proximal third, middle third and distal third of the femoral head, respectively, and zone 5 below the inferior border of the femoral head (Figure 1). The bifurcation of the CFA occurred in zones 2, 3, 4 and 5, which was 1%, 9%, 43% and 47% of the time, respectively, and thus occurred within the lower third of the femoral head or below the lower border of the femoral head in 90% of patients (Table 2). Arterial entry site. Arterial puncture over the femoral head (i.e., zones 2, 3 or 4) occurred in 100 patients (92%) in the palpation group and in 93 patients (95%) in the palpation + fluoroscopy group (p = 0.27; Table 2). The majority of arterial punctures in both groups occurred in zone 3, in 52% of the palpation group and in 53% of the palpation + fluoroscopy group. A total of 8% of the arterial punctures in the palpation group were distal to the femoral head (i.e., zone 5) compared to 5% in the palpation + fluoroscopy group. Successful CFA puncture occurred in 94 (85%) patients randomized to palpation versus 88 (90%) patients randomized to palpation + fluoroscopy (p = 0.49; Figure 2). Cannulation of the external iliac artery was rare, occurring in 1 patient in each group. Arterial puncture distal to the CFA bifurcation occurred in 16 (15%) patients in the palpation group and in 9 (9%) patients in the palpation + fluoroscopy group (p = 0.33; Table 3). Vascular complications. The study was not powered to look at clinical events, but patients in the study were monitored for vascular complications. Access-site complications occurred in 3 patients in the palpation group and in 5 patients in the palpation + fluoroscopy group. In the palpation group, 3 subjects developed a hematoma, none of which required a blood transfusion. In the palpation + fluoroscopy group, 2 patients developed hematomas not requiring blood transfusions and 1 patient developed a hematoma requiring a blood transfusion (2 units of PRBC). In the palpation + fluoroscopy group, 1 patient developed a linear iliac dissection at the tip of a 7 Fr sheath not requiring any further intervention and 1 patient developed an iliac dissection at the tip of a 6 Fr sheath requiring iliac stenting to restore blood flow to the lower extremity. All 5 patients with access-site complications had undergone successful CFA cannulation in either zone 2 or 3. The patient requiring iliac stenting was an elderly female with severe peripheral arterial disease. All 6 patients who developed hematomas had undergone manual sheath-pulls. Two patients did not receive any intravenous (IV) anticoagulation, 2 received bivalirudin and 2 patients received IV unfractionated heparin and eptifibatide. Overall, 7% of the patients in this study received a glycoprotein IIb/IIIa inhibitor (6% eptifibatide and 1% abciximab) and 24% received bivalirudin. There were no retroperitoneal bleeds, arteriovenous fistulae or pseudoaneurysms.

Discussion

In this single-center, randomized study of 208 patients, we found that a strategy of using fluoroscopy in conjunction with palpation as opposed to palpation alone did not improve common femoral artery cannulation in patients with palpable pulses, weighing less than 300 lbs undergoing cardiac catheterization via transfemoral arterial access. There was no difference between the groups with successful CFA punctures (85% of the palpation group vs. 90% of the palpation + fluoroscopy group; p = 0.41) or in arterial punctures over the femoral head (91% of the palpation group vs. 95% of the palpation + fluoroscopy group; p = 0.27). Vascular complications are an important risk of cardiac catheterization. The incidence of femoral artery complications in a recent study was 1.8% for diagnostic and 4% for interventional procedures.13 Vascular complications during cardiac catheterization lengthen hospital stay, may necessitate surgery and are associated with increased morbidity and mortality.¹ For example, in an analysis of 6,656 patients in the National Heart, Lung and Blood Institute (NHLBI) Dynamic Registry, an access-site hematoma that required transfusion was associated with a 9-fold increase in hospital death and a 4.5-fold increase in 1-year mortality in patients undergoing PCI and was a strong and independent predictor of in-hospital and 1-year mortality.² Similarly, in a single-center study of 10,669 patients undergoing PCI, vascular complications were associated with higher rates of MI, coronary artery bypass grafting and death, both during the hospitalization and at 1-year follow up. Multivariate analysis identified vascular complications as a significant predictor of 1-year mortality.¹ Risk factors for vascular complications are both clinical and anatomic and include age, female gender, weight, uncontrolled hypertension, previous arteriotomy at the same site, type and level of anticoagulation, arterial sheath size, renal failure, concomitant venous sheath, peripheral vascular disease, prolonged sheath duration and location of the arteriotomy. The importance of the arteriotomy site was highlighted by the study of Sherev et al⁷ who compared 33 patients with femoral access site complications to a randomly selected control group and found that an arteriotomy site in the CFA was associated with the fewest vascular complications. Arterial puncture above the inferior epigastric artery or below the CFA bifurcation was associated with a relative risk of vascular complications of 29 when compared to cannulation of the CFA. In a retrospective analysis of factors associated with retroperitoneal hematoma in 3,508 consecutive patients undergoing PCI,¹⁴ Farouque et al found that while the overall incidence of retroperitoneal hematoma was low (0.74%), higher femoral artery puncture (defined as in the proximal third of the femoral head or above), as well as female gender and low body surface area, were independent variables associated with increased risk. While there are theoretical benefits to the use of fluoroscopy to guide arterial access, prior to the present study, there were no randomized trials examining this question. In a nonrandomized study where the method used to obtain arterial access was at the discretion of the invasive cardiologist, the use of fluoroscopy was associated with a significantly lower incidence of pseudoaneurysms and any arterial injury in 2,651 consecutive percutaneous interventions performed at a single center in Maine.¹⁵ Interpretation of the value of fluoroscopy based on these data is limited, however, since the patients were not randomized and information was not available on potential confounders such as the level of anticoagulation or sheath size. Furthermore, femoral angiography was not performed and thus whether fluoroscopy led to a greater likelihood of cannulation of the CFA was not determined. This study provides more evidence that the femoral head offers a reliable landmark for identifying the CFA. In prior angiographic studies, the bifurcation of the CFA was below the center of the femoral head in 98.5% of individuals in a study of 200 patients undergoing angiography for clinical indication9 and in 99% of individuals in a study of 158 patients undergoing cardiac catheterization.¹⁶ In a study utilizing computed tomographic imaging, the bifurcation of the CFA was consistently below the center of the femoral head and always caudal to the level of the inguinal ligament.8 In the current study, the bifurcation of the CFA occurred within the upper-third of the femoral head in only 1% of patients and within the middle-third of the femoral head in 9% of patients. While there is a lack of consensus on the fluoroscopic landmark(s) to use for CFA access, the available data indicate that arterial entry in the upper-third of the femoral head will avoid the CFA bifurcation in approximately 99% of patients. Study limitations. First, the sample size was relatively small and thus the present study is prone to a type II statistical error. Although at 208 patients this is one of the largest randomized studies examining different approaches to vascular access that have been reported, the relatively high rate of successful cannulations of the CFA in the palpation group (85%) means that approximately 1,400 patients would have to be enrolled to have a power of 80% to conclude that a mean difference of 5% in the rate of successful CFA access was statistically significant. Second, this study did not enroll patients with weight > 136.4 kg (300 lbs), serum creatinine > 2 mg/dl, lack of a palpable femoral pulse or concurrent venous access. Fluoroscopy may be a useful adjunct in these patients, especially those who are morbidly obese or lacking a palpable femoral pulse. Furthermore, optimal access in these patients may not be via the femoral artery, irrespective of the method used to cannulate this artery.¹⁷ Another limitation was that the arterial entry site was within the middle-third of the femoral head in only 53% of patients in the fluoroscopy group (a rate similar to that in the palpation group; 52%) despite the optimal site of entry in this study being defined as the middle of the femoral head. These data suggest that the accuracy of fluoroscopic localization of arterial entry by the operators in this study could be improved. Alternatively, these data may suggest an intrinsic limitation of the fluoroscopic method whereby factors such as body habitus and needle angle may limit the accuracy of fluoroscopic localization of the arterial entry site. Lastly, this study was not powered to evaluate vascular complications. Overall, the complication rate was low, similar in both groups and consistent with expected complication rates in this patient population.

Conclusion

In summary, in this single-center, randomized trial of patients undergoing cardiac catheterization, arterial access using fluoroscopy to identify the middle of the femoral head as the planned site for arterial entry increased the amount of time required for access (by approximately 1 minute) and the number of needle passes, but did not increase the rate of successful CFA punctures or the probability of arterial puncture over the femoral head. There was a slight improvement in successful CFA cannulations (85% vs. 90%) and avoidance of zones 4 and 5 (15% vs. 9%) with the use of fluoroscopy, but these differences did not achieve statistical significance. Acknowledgments. This study was funded by an unrestricted grant from St. Jude Medical. St. Jude Medical did not participate in any portion of the study design, implementation or analysis.

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