Author + information
- Received September 23, 2013
- Revision received November 21, 2013
- Accepted November 25, 2013
- Published online July 1, 2014.
- Herman Kado, MD,
- Ambar M. Patel, MD,
- Siva Suryadevara, MD,
- Martin M. Zenni, MD,
- Lyndon C. Box, MD,
- Dominick J. Angiolillo, MD, PhD,
- Theodore A. Bass, MD and
- Luis A. Guzman, MD∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Luis A. Guzman, University of Florida College of Medicine–Jacksonville, UF Health Cardiovascular Center, 655 West 8th Street (ACC 5th floor), Jacksonville, Florida 32209.
Objectives This study sought to assess radiation exposure and operator discomfort when using left radial approach (LRA) versus right radial approach (RRA) for coronary diagnostic and percutaneous interventions.
Background The transradial approach is increasingly being adopted as the preferred vascular access for coronary interventions. Currently, most are performed using an RRA. This is in part due to the perceived increased operator physical discomforts as well increased radiation exposure with an LRA.
Methods One hundred patients were randomized to an LRA or RRA. Each operator (n = 5) had an independent randomization process, and patients were stratified according to obesity status. Operator radiation was measured using separate sets of radiation dosimeter badges placed externally on the head and thyroid and internally on the sternum. Operator physical discomfort was surveyed at 2 time points: during vascular access and at the end of the procedure. Moderate to severe physical discomfort was defined as a score of >4.
Results There were no significant differences in baseline and procedural variables between groups. There was a significant increase in external radiation exposure using the RRA versus LRA (head: median: 6.12 [interquartile range (IQR): 2.6 to 16.6] mRems vs. median: 12.0 [IQR: 6.4 to 22.0] mRems, p = 0.02; thyroid: median: 10.10 [IQR: 4.3 to 25] mRems vs. median: 18.70 [IQR: 11.0 to 38] mRems, p = 0.001). More discomfort was reported with the LRA during access (LRA: 22% vs. RRA: 4%; p = 0.017), but not during the procedure (LRA: 10.0% vs. RRA: 4.0%, p = 0.43). This difference was almost entirely noted in obese patients (LRA: 30.0% vs. RRA: 3.7%, p = 0.005).
Conclusions LRA is as effective as RRA, showing a safer profile with decreased radiation exposure to the operator, at the expense of more operator discomfort only during vascular access and limited to obese patients.
Transradial artery access is a safe and effective approach in patients undergoing percutaneous coronary interventions. The benefits of transradial artery access include lower incidence of access-site bleeding complications, decreased patient discomfort, promoted patient ambulation, and decreased length of hospital stay when compared with the benefits of a transfemoral approach (1). Steadily increasing in use, the transradial approach is now considered the standard of care in many centers (2).
Most data comparing femoral with radial access derive from studies using a right radial approach (RRA), and there are limited data comparing RRA with left radial approach (LRA). Historical data have shown increased radiation exposure with radial access, mostly RRA, compared with exposure with femoral access. Moreover, trials have shown a significant increase in procedure time, radiation exposure, and room time using the LRA compared with the RRA (3). It has been suggested that the LRA presents greater difficulty for the operator, especially if the patient is obese or the operator is short. However, pitfalls in these studies may have contributed to these observations. A recent large randomized trial suggested that, when compared with an RRA, an LRA is associated with lower fluoroscopy time (FT) (4). LRA is also associated with less operator radiation exposure to the wrist (5). Furthermore, when compared with LRA, RRA is known to be complicated by a higher frequency of failure due to anatomical variations, including a higher rate of right subclavian artery tortuosity, especially in elderly patients (6,7). To overcome the limitations of previously reported data on radial access, we conducted a prospective randomized study with the aim of assessing radiation exposure and operator discomfort when using LRA versus RRA for coronary diagnostic and percutaneous interventions.
This was a single center, prospective, randomized study conducted from July 2011 to October 2012. Patients were screened at the Division of Cardiology of the University of Florida College of Medicine–UF Health Jacksonville. A total of 100 patients undergoing transradial left heart catheterization, with or without the possibility of percutaneous coronary intervention, were randomly assigned to LRA or RRA. Procedures were performed by 5 operators with different levels of experience in transradial approach, ranging from 1 year of experience and 100 radial procedures performed to >15 years of experience and >1,000 radial procedures performed. Patients presenting with ST-segment elevation myocardial infarction, hemodynamic instability, previous coronary artery bypass graft, arteriovenous fistulas for hemodialysis, nonpalpable radial pulse, or an abnormal Allen test and who were <18 or >80 years of age were excluded from the study.
Study design and procedures
The study protocol and design was approved by the local institutional review board committee at the University of Florida College of Medicine—Jacksonville. After providing written informed consent, patients were randomized to RRA or LRA using a computer-generated 1:1 sequence that was unique to each operator, with the intention of avoiding operator-related imbalance. In addition, to warrant balance among both access groups, patients were stratified according to obesity status, defined as body mass index (BMI) ≥30 mg/kg2. Therefore, each operator had a total of 4 sets of 3 radiation badges (left radial + high BMI, left radial + normal BMI, right radial + high BMI, and right radial + normal BMI) to assess for radiation exposure.
For patients assigned to RRA, the patient's right arm was secured to an arm board on the same side of the operator. For patients assigned to LRA, the left arm was elevated with appropriate support and rotated in order to be supine. The left digits were restrained with orthopedic finger traps connected with a sling. After access was obtained, the sling holding the finger was pulled and secured, mobilizing the left forearm toward the right side of the table, and closer to the operator to perform the procedure (Fig. 1).
Radial artery access was obtained by modified Seldinger technique with an 18-gauge needle. A 5-F or 6-F hydrophilic radial sheath was used (Terumo Corporation, Tokyo, Japan). Administration of verapamil (3 mg) and unfractionated heparin (3,000 IU) were provided intra-arterially through the radial sheath before the initiation of the procedure. A 0.035-inch J-tip wire was inserted and used to introduce the catheters. A 2-catheter procedure was performed in all patients with mandatory Judkins diagnostic catheters as the initial attempt for coronary angiography. Use of additional equipment, that is, additional wires or catheters, was on the basis of the clinical judgment of the operator. All diagnostic procedures used a minimum of 2 views for selective right coronary angiogram and a minimum of 4 views for left coronary angiogram, with additional projections allowed at the discretion of the operator. Additional views were also obtained as deemed necessary for any interventions. Upon removal of the transradial sheath, an inflatable transradial band (Terumo Corporation) was used to compress the artery to obtain hemostasis.
All operators performed the procedure from the patients' anatomical right side. Operator's radiation protection included the standard lead apron, a thyroid lead collar, leaded glasses, low-leaded flaps, and an upper mobile leaded glass suspended from the ceiling in all procedures. Operator radiation exposure was assessed with a set of 3 aluminum oxide radiation detection dosimeters (Landauer Inc., Glenwood, Illinois) strategically placed in 3 separate locations: 1) head: external on the left side of leaded glasses, 2) thyroid: external to the lead collar, and 3) sternum: interior to the lead apron. Separate sets of dosimeters were worn for RRA versus LRA. Badges' radiation levels were checked every 2 months for total exposure dose measured in milliRems; the total exposure dose for each operator was divided by the total FT performed in the 2-month period to obtain the dose per case at each location. Direct environmental radiation exposure to the patient was calculated using fluoroscopy suite software (Siemens AG, Munich, Germany) and expressed in milliGreys.
Study endpoints and sample size calculations
The primary endpoint of the study was to determine the difference in total head and external thyroid radiation doses between LRA and RRA as directly measured on dosimeter badges. Due to the lack of information regarding radiation exposure to the operator at the time of the study design, to determine the sample size we performed a pilot analysis of the radiation exposure after completing the first 25 randomized patients (8). We hypothesized that left radial access would be associated with less radiation exposure. On the basis of our pilot findings, it was determined that a minimum of 80 patients were needed to power the study to demonstrate differences in operator radiation exposure at both external detectors (2-sided alpha: 0.05; power 80%).
The secondary endpoint was operator physical discomfort. Physical discomfort was measured using a 0 to 10 scale (0 being no discomfort and 10 a very severe discomfort) to measure back, leg, and neck pain at 2 distinct time points: at the time of vascular access and at the end of the procedure. Moderate to severe operator physical discomfort was defined as a score of >4.
Continuous variables are expressed as mean ± SD or as median (interquartile range) for non-normally distributed data. Categorical variables are expressed as frequencies and percents. Student t test was used to compare continuous variables that were then confirmed using Mann-Whitney U tests for non-normally distributed data. A chi-square analysis or Fisher exact test was used to compare categorical variables. A p value of <0.05 was considered statistically significant. Statistical analysis was performed using SPSS software (version 21.0, SPSS Inc., Chicago, Illinois).
Study population and procedural outcomes
One hundred patients were randomized to LRA (n = 50) or RRA (n = 50) There were no significant differences in baseline clinical characteristics with similar age, BMI, sex, race, coronary risk factors, and clinical indications between the 2 groups (Table 1). The procedural success, defined by the ability to complete diagnostic angiography and percutaneous intervention if required using the initial assigned radial approach, did not differ between the 2 groups (LRA: 96%, RRA: 96%; p = 1.0) (Table 2). The reason for failure included 1 patient with severe radial spasms and 1 patient with a radial occlusion. The crossover rate to femoral artery approach was 2%.
Variables associated to procedural performance were very similar in both groups. (Table 2). There were no significant differences in number of catheters used (LRA: 3.02 ± 1.08 vs. RRA: 2.78 ± 1.4, p = 0.45), FT (LRA: 10.5 ± 7.9 min vs. RRA: 10.9 ± 8.0 min; p = 0.82), contrast load (LRA: 110.1 ± 58.8 ml vs. RRA: 104.55 ± 60.0 ml; p = 0.65), and acquired scenes (LRA: 13.7 ± 8.5 scenes vs. RRA: 14.4 ± 9.4 scenes; p = 0.71). Direct environmental radiation exposure to the patient did not vary by approach (LRA: 1,484.3 ± 974.4 mGy vs. RRA: 1,727.8 ± 1,381.4 mGy; p = 0.59) (Table 2).
Operator radiation exposure
A significant variation in radiation dose absorbed by the operator as directly measured using the designated dosimeters was observed (Fig. 2). In particular, dosimeters positioned at the head (LRA: median: 6.12 [IQR: 2.6 to 16.6] mRems vs. RRA: median: 12.0 [IQR: 6.4 to 22.0] mRems; p = 0.018) and external thyroid (LRA: median: 10.10 [IQR: 4.3 to 25] mRems vs. RRA: median: 18.70 [IQR: 11.0 to 38.0] mRems; p = 0.001) revealed significantly more radiation to the operator using RRA. The internal sternum measurements failed to show significant difference in the 2 approaches (LRA: median: 0.50 [IQR: 0.0 to 1.2] vs. RRA: median: 0.71 [IQR: 0.0 to 2.4] mRems; p = 0.34) (Fig. 2).
Operator radiation exposure and patient obesity status
BMI in the overall study population was 31.4 ± 7.4. Obesity status (BMI ≥30 mg/kg2) was observed in 56% of the study population. Direct radiation exposure to the patient did not vary according to obesity status (obese vs. nonobese, 1,666.2 ± 1,028.2 mGy vs. 1,530.7 ± 1,375.5 mGy; p = 0.58). BMI was also not associated with more radiation exposure to the operator in any of the 3 evaluated locations (Table 3). However, when comparing the 2 approaches in patients stratified according to obesity status, there was a significant increase in radiation in head and external thyroid exposure in RRA versus LRA. The difference was predominantly observed in nonobese patients. A trend toward a statistically significant increase in radiation exposure at the thyroid level was found with the RRA in obese patients (Table 3).
LRA was associated with more moderate to severe discomfort (>4 on a 0 to 10 scale) only at the time of vascular access (LRA: 22% vs. RRA: 4%; p = 0.017) (Fig. 3). However, by the end of the procedure, there were no differences in the level of operator discomfort between the 2 radial approaches. The difference in operator discomfort during access using the LRA was almost entirely noted in obese patients (LRA: 30.0% vs. RRA: 3.7%, p = 0.005), whereas there were no significant differences in nonobese patients (LRA: 10.0% vs. RRA: 5.0%, p = 0.58).
The main finding of our study is that operators are exposed to a greater degree of direct radiation when performing coronary angiography and interventions using the RRA, without subjecting patients to increased radiation. Additionally, there was higher reporting of operator discomfort with the LRA at the time of obtaining vascular access, without differences by the end of the procedure. This difference was almost entirely noted in obese patients.
Currently, among patients undergoing left heart catheterization with radial access, an RRA is used in nearly 90% of cases (3). The reasons for a more selective use of RRA over LRA is unclear, although likely they derive from historical data and misperceptions. This may be due to the fact that fluoroscopy suites are typically designed so that the operator stands to the right of the patient, making RRA more convenient to perform. The operator can thus avoid the physical discomfort associated with bending over the patient to gain access for LRA. Besides, there has been concern that reaching across the patient's body to perform LRA would expose the operator to more radiation. However, these concerns are unfounded and have not been supported with trial data. In line with several recent reports, our study confirms that both RRA and LRA have similar success rates as well as similar indicators of procedural performance on the basis of almost identical numbers of catheters used, contrast load, FT, and number of cine scenes taken (4,6,9–11). It has been established that LRA has favorable anatomy due to direct takeoff of the left subclavian artery from the aortic arch, providing support for equipment similar to the femoral approach (6-7,12). There is also a lower frequency of vessel tortuosity when compared with the right approach (13–15). These anatomical benefits, as well as the favorable collective data including our findings suggest that either radial artery could be used for radial access coronary procedures.
Very few studies to date have measured direct operator radiation exposure comparing RRA or LRA. The TALENT dosimetric substudy (Transradial Approach LEft versus right aNd procedural Times during percutaneous coronary procedures) (5) was the first study to detect significantly more radiation absorbed on the left wrist of the operator with RRA versus LRA. However, no significant differences in badges placed on the thyroid, thorax or shoulder were noted. Similarly, the recently reported OPERA (Operator Exposure to X-Ray in Left and Right Radial Access During Percutaneous Coronary Procedures) study (9) placed a single dosimeter on the left side of the operator's neck, which detected a significantly greater amount of radiation absorbed with RRA. Both studies were able to appreciate greater radiation exposure with RRA despite no significant difference in patient radiation exposure, contrast load, or FT. These findings are consistent with our study, which measured a significant difference in dosimeters placed on the operator's left side of the head and external thyroid despite there being no significant difference in radiation exposure, contrast load, or FT. The present study extends our knowledge that at the head level, close to the eyes, there is a significant increase in radiation exposure with RRA. This has important implications, because the association between radiation doses and development of cataract as well as the increased incidence of left-sided brain tumors among interventionalists has been well described (16–18).
Our study is the first to randomize patients to LRA or RRA according to patient's obesity status. Importantly, our study included a significant number of obese patients, reflecting real-world practice in the United States and which represents a concern for the uptake of radial approach in the United States. The vast majority of patients enrolled in LRA versus RRA studies have been enrolled in European and Asian countries (7,10), which have a markedly lower prevalence of obesity than does the United States (5–12,19). Some investigators hypothesized that performing radial catheterization on obese patients will lead to a decreased success rate and it has been suggested that the RRA approach is the preferred approach in obese patients (7). Our study found that obese status did not result in significantly more radiation exposure to the operator as compared with using LRA on nonobese patients. Moreover, the present study showed that RRA is associated with increased radiation exposure to the operator, to all patients, including obese patients. On the basis of these these findings, the radial approach does not appear to be associated to increase radiation in obese patients, with LRA being a viable option.
The reason for increased radiation when using RRA versus LRA is not well established. As suggested by others, the upper mobile suspended lead glass might explain some of the differences in radiation exposure (5). When the procedure is performed using RRA, the lead is placed over the right arm, whereas it is placed over the body of the patient when LRA is used, which could shield the operator better. Additionally, the process of pulling the left arm over the abdomen toward the left groin area of the patient might help decrease the need for lying over the left side to reach for the catheter with the subsequent decrease in radiation to the operator. Radiation exposure to the operator is frequently overlooked. However, there are important consequences due to the stochastic risk of cancer induction (20). In fact, current quality initiatives include FT and patient as well as operator radiation exposure as main improvement targets (21). In addition to access site selection, new protection devices have been recently developed and evaluated in clinical practice with significant improvements in radiation protection (22–25). Encouraging results in decreasing scatter radiation with the use of Radpad (Worldwide Innovations & Technologies, Kansas City, Missouri), a sterile disposable shield drape was recently reported, with a 23% reduction in operator radiation exposure (22). Another exciting area of development has been the incorporation of robotic systems, such as the CorPath 200 (Corindus Vascular Robotics, Waltham, Massachusetts), which have been able to demonstrate safety and feasibility with the potential benefit of nearly completely eliminating radiation exposure to the operator (25).
Operator discomfort has been a main complaint with the use of LRA, although there is limited data to objectively define this. We prospectively evaluated operator discomfort at 2 different time points. By creating an objective scale, the study shows that LRA is in fact associated with greater operator discomfort. However, the main complaint was reported only at the time of getting access and noted only in obese patients, with no differences among nonobese patients. On the other hand, by the end of the procedure, no differences between the 2 approaches were reported. These findings suggest that the proposed reason for not doing LRA due to increase operator discomfort appears unfounded in nonobese patients. In obese patients, increased discomfort occurs only at the time of obtaining vascular access. As described herein, the process of pulling the left arm over the abdomen toward the left groin area of the patient used in our institution might have helped decrease the discomfort for lying over the left side to perform the procedure. Because at the time of obtaining access the arm is still on the left side of the body, this probably explains the reported discomfort during arterial access.
This was a single center study. Therefore, these results cannot be generalized to other catheterization laboratories, because major differences in operator training, protection devices, and lab setup might exist. Even though the study clearly shows that the radiation advantages with the LRA can be extended to obese patients, the vast majority of the included obese patients have BMI between 30 and 40 mg/kg2. Morbidly obese patients, with BMI >40 may be a more challenging group in which radiation exposure and operator discomfort might be higher, and that would potentially benefit from use of RRA. Ultimately, this study has a rather small sample size and warrants confirmation in a larger trial.
LRA is as effective as RRA for diagnostic and interventional coronary procedures. However, LRA has a safer profile with decreased radiation exposure to the operator than does RRA. This occurs at the expense of more operator discomfort during vascular access, but not during the procedure, and is limited to performing the technique on obese patients. Larger studies are warranted to confirm the results of this trial.
Dr. Angiolillo has received consulting fees or honoraria from Bristol-Myers Squibb, Sanofi-Aventis, Eli Lilly, Daiichi Sankyo, The Medicines Company, AstraZeneca, Merck & Co., Inc., Evolva, Abbott Vascular, and PLx Pharma; has received compensation for participating in review activities for Johnson & Johnson, St. Jude, and Sunovion; has received institutional payments for grants from Bristol-Myers Squibbhttp://dx.doi.org/10.13039/100002491, Sanofi-Aventis, GlaxoSmithKlinehttp://dx.doi.org/10.13039/100004330, Otsuka, Eli Lilly, Daiichi-Sankyohttp://dx.doi.org/10.13039/501100002973, The Medicines Company, AstraZenecahttp://dx.doi.org/10.13039/100004325, Evolva; and has other financial relationships with Esther and King Biomedical Research Grant. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- body mass index
- fluoroscopy time
- left radial approach
- right radial approach
- Received September 23, 2013.
- Revision received November 21, 2013.
- Accepted November 25, 2013.
- American College of Cardiology Foundation
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