Article

PDF
Access to the PDF text
Advertising


Free Article !

Archives of cardiovascular diseases
Volume 102, n° 11
pages 749-754 (novembre 2009)
Doi : 10.1016/j.acvd.2009.09.006
Received : 24 June 2009 ;  accepted : 10 September 2009
Impact of an extension tube on operator radiation exposure during coronary procedures performed through the radial approach
Impact d’un système de rallonge sur l’irradiation reçue par l’opérateur au cours d’une procédure de cardiologie interventionnelle par voie radiale
 

Nicolas Marque , Arnaud Jégou, Olivier Varenne, Emmanuel Salengro, Philippe Allouch, Olivier Margot, Christian Spaulding
Service de cardiologie, hôpital Cochin, 27, rue du Faubourg-Saint-Jacques, 75014 Paris, France 

Corresponding author.
Summary
Background

Operator radiation exposure is high during coronary procedures. The radial access decreases the rate of local vascular complications but increases operator radiation exposure. As the X-ray exposure is related to the distance between the operator and the radiation source, the use of an extension tube between the proximal part of the coronary catheter and the ‘injection device’ might decrease operator radiation exposure.

Aims

To demonstrate that the use of an extension tube during coronary procedures performed through the radial approach decreases operator radiation.

Methods

Overall, 230 patients were included consecutively and randomized to procedures performed with or without an extension tube. Radiation exposure measures were obtained using two electronic dosimeters, one under the lead apron and the other exposed on the physician’s left arm.

Results

A non-significant trend towards lower left-arm operator exposure was noted in the extension tube group (28.7±31.0μSv vs 38.4±44.2μSv, p =0.0739). No significant difference was noted according to the type of procedure. Radiation levels were low compared with the series published previously and decreased for each operator during the study.

Conclusion

The use of an extension tube did not reduce operator radiation exposure during procedures performed through the radial approach. However, physician awareness was increased during the study due to the use of an exposed electronic dosimeter. The use of exposed electronic dosimeters could therefore be recommended to allow operators to improve their protection techniques.

The full text of this article is available in PDF format.
Résumé
Introduction

L’irradiation de l’opérateur est non négligeable en cardiologie interventionnelle. La voie d’abord radiale diminue les complications vasculaires locales, mais augmente l’exposition du praticien. L’irradiation étant inversement proportionnelle à la distance par rapport à la source d’émission, tout moyen de s’éloigner de la source de rayons X devrait diminuer l’exposition.

But

Démontrer que l’utilisation d’une rallonge entre le cathéter et la rampe de pression permettrait de diminuer l’irradiation de l’opérateur par voie radiale.

Méthodes

Deux cent trente patients consécutifs ont été inclus et randomisés en deux groupes : avec, et sans cette rallonge. Les mesures d’irradiation étaient réalisées grâce à deux dosimètres électroniques, l’un placé au niveau du thorax sous le tablier de plomb, et l’autre exposé au niveau du bras gauche de l’opérateur.

Résultats

Aucune différence significative n’est retrouvée entre les deux groupes. Cependant, il existe une tendance de diminution de la dose reçue au niveau du dosimètre exposé pour les examens réalisés avec rallonge : (28,7±31,0μSv versus 38,4±44,2μSv, p =0,0739). Les niveaux d’irradiation des opérateurs étaient faibles comparés aux chiffres rapportés dans les études précédentes, et ont diminué pour chaque opérateur au cours de l’étude.

Conclusion

L’utilisation d’une rallonge entre le cathéter et la rampe de pression n’a pas permis de diminuer l’irradiation de l’opérateur durant les procédures coronaires réalisées par voie radiale. L’utilisation d’un dosimètre électronique exposé a eu comme effet de sensibiliser l’équipe aux problèmes de radioprotection. Ce matériel pourrait être recommandé en pratique courante pour optimiser les pratiques des opérateurs en matière de radioprotection.

The full text of this article is available in PDF format.

Abbreviations : CA, PCI

Keywords : Coronary arteries, Radial approach, Radiation exposure, Dosimeter

Mots clés : Coronaires, Abord radial, Irradiation, Dosimètre


Background

Because of an increase in the use of cardiac imaging techniques, there is growing concern about the consequences of radiation exposure, especially for interventional cardiologists [1, 2, 3]. Prolonged radiation exposure can induce major and potentially lethal complications [4]. Therefore, the use of X-rays is highly regulated and effective techniques to reduce cumulative doses for the patient and the operator have been described [5]. The use of the radial approach seems to increase operator exposure compared with the femoral approach, even when optimal protection techniques and devices are used [6, 7]. However, the radial approach decreases hospital stay and vascular complication rate, and increases patient comfort [8, 9]. It is therefore the preferred approach in many interventional cardiology centres in Europe. Operator exposure can be reduced by increasing the distance from the radiation source (inverse-square law). A simple way to increase the distance is to connect a 30cm extension tube between the proximal part of the coronary catheter and the injection device (Figure 1). We therefore performed a randomized trial to compare operator radiation exposure during coronary procedures performed through the left radial approach, with and without the use of an extension tube.



Figure 1


Figure 1. 

The extension tube.

Zoom

Methods

Operators used left-arm and thoracic electronic personal dosimeters (model: DMC 2000 MGP). The thoracic dosimeter was placed under the lead apron and the left-arm dosimeter was placed outside of the personal protection. The left-arm dosimeter reflects brain exposure [6, 7, 10]. Protection of operators was ensured using a lead apron, low leaded flaps and leaded glass (0.5mm leaded equivalent for each) in all procedures (Figure 2).



Figure 2


Figure 2. 

Operator radiation protection devices.

Zoom

Age, patient weight, body surface, procedure duration, patient radiation exposure and procedural complications were gathered prospectively and entered into a database.

CAs followed by ad hoc PCIs were performed using an eight-year-old digital single-plane cineangiography unit (Integris 5000, Phillips Medical Systems, The Netherlands) A film speed of 12.5 frame/s was selected. All procedures were carried out with respect to current guidelines using 5F or 6F catheters. CAs were recorded using a 17cm field. Two left ventriculograms were performed on a routine basis using a 23cm field. Medium contrast was injected manually using a 10mL syringe without specific assistance injection devices.

Patients were randomized according to their year of birth (even or odd). In patients with an odd year of birth, the procedure was performed using an extension tube between the catheter and the injection device.

All patients, including those undergoing emergency procedures, were screened. Exclusion criteria were limited to history of coronary artery bypass surgery and to procedures performed through the femoral approach. Before collecting the data, informed consent was obtained from the patients.

Statistical analysis

We hypothesized that the use of an extension tube would allow the operator to perform a radial procedure at a distance similar to that for a femoral procedure. In previous studies, the level of radiation exposure by the radial approach was 25–50% higher than with the femoral approach [6, 7, 11]. In order to detect a 35% relative reduction in operator exposure with a unilateral value of 0.05 and a β value of 0.1, 110 patients had to be enrolled into each group.

Data are expressed as means±standard deviations for continuous variables and numbers and percentages for categorical variables. Data in both groups (with and without extension tube) were compared using Student’s t -test for comparisons of normally distributed continuous variables, and the chi-square or Fisher’s exact test for differences in frequency, as appropriate. A p -value<0.05 was considered to be statistically significant. STATA statistical software, version 9.2 (StataCorp LP, College Station, TX, USA) was used for all data analysis.

Results

A total of 230 patients were included between 1 January and 30 March 2008. Procedures were performed by five operators with extensive experience in the radial approach (over 1000 procedures). A CA was performed in 141 patients and a methyergonovine provocation test was performed in 36 patients with normal coronary arteries. PCI was performed in 53 patients. Baseline clinical characteristics were similar between groups (Table 1).

There was no difference between groups in thoracic operator radiation exposure measured under the lead apron, with surprisingly low doses (0.00019±0.6mSv with extension tube and 0.00029±0.54 mSv without extension tube). There was a trend towards lower left-arm operator exposure in the extension tube group when all the procedures were analysed (with vs without extension tube: 28.7±31.0μSv vs 38.4±44.2μSv, p =0.0739). No significant difference was noted according to the type of procedure (CA, CA with provocation test, PCI).

Patient radiation exposure was similar between groups in patients with CA with provocation test (with vs without extension tube: 56.5±30.6Gy/cm2 vs 57.7±31.7Gy/cm2, p =0.815) and without provocation test (with vs without extension tube: 63.9±35.7Gy/cm2 vs 60.3±32.9Gy/cm2, p =0.751). In contrast, patient radiation exposure was significantly lower during PCI procedures in the group with the extension tube (with vs without extension tube: 72.6±40.7Gy/cm2 vs 115.9±69.8Gy/cm2, p =0.015).

Fluoroscopic time was similar between groups when CAs were performed with provocation test (with vs without extension tube: 5.2±3.9min vs 4.6±2.5min, p =0.277) or without provocation test (with vs without extension tube: 6.3±2.5min vs 5.2±2.0min, p =0.158). When PCI was performed, fluoroscopic time was significantly lower in the group with the extension tube (with vs without extension tube: 7.3±4.2min vs 11.5±8.2min, p =0.037) (Table 2).

Three operators performed most (75%) of the procedures. No significant difference was found in operator radiation exposure (operator 1: 52 procedures, 33.8μSv; operator 2: 65 procedures, 29.7μSv; operator 3: 57 procedures, 35.9μSv).

There were no major complications. Air embolism with no sequella occurred during one procedure in the group without the extension tube and during three procedures in the group with the extension tube.

Discussion

In this study, the use of an extension tube during coronary interventions did not reduce operator radiation exposure significantly.

Ionizing radiation at high doses (i.e., 1–10Gy) is not associated with most CAs and/or PCIs. However, high patient radiation exposure has been described during complex PCIs, such as chronic total occlusion. The deterministic effects are predictable and range from blood and chromosome aberrations to death, depending on the dose and type of radiation exposure. In contrast, chronic low-dose radiation exposure is related to an increased risk of stochastic (random) effects. In this setting, the odds of having any effect are extremely low but unpredictable. To educate operators, training in the use of radiation and radioprotection is mandatory in Europe and the USA [10].

Conflicting data on operator and patient radiation exposure during femoral and radial procedures have been published [12, 13, 14]. Lange et al. measured the operator radiation exposure in an experienced single operator and noted a 100% increase when the procedures were performed by the radial compared with the femoral approach (64±55μSv vs 32±39μSv, p <0.001 for CAs and 166±188μSv vs 110±115μSv, p <0.05 for PCIs, respectively). However, the radiation protection strategy was divergent between both groups, as the upper protective shield flap was used only in femoral cases, whereas it was flipped down in radial cases. Recently, Brasselet et al. performed an operator-blinded registry and compared operator radiation exposure between femoral and radial procedures. Radiation exposure of operators was significantly higher using the radial route compared with the femoral route for both CAs and CAs followed by ad hoc PCIs (29.0 [1.0–195.0] μSv vs 13.0 [1.0–164.0] μSv, p =0.0001 and 69.5 [4.0–531.0] μSv vs 41.0 [2.0–360.0] μSv, p =0.018, respectively). Similarly, radiation exposure of patients was significantly higher using the radial route compared with the femoral route for both CAs and CAs followed by ad hoc PCIs. Moreover, procedural durations and fluoroscopy times were significantly higher with the radial route. Several studies have shown that operator experience of the radial approach is a major factor in reducing procedural and fluoroscopic duration [12, 13]. Another factor is the distance between the operator and the radiation source, which is shorter when procedures are performed through the radial artery. As radiation exposure decreases significantly with distance (inverse-square law), we hypothesized that the use of an extension tube would allow the operator to perform a radial procedure at a distance similar to that for a femoral procedure. The benefit of the radial approach for the patient would therefore be achieved without an increase in operator radiation exposure.

We found a trend towards lower operator radiation exposure measured by an electronic dosimeter on the left arm when an extension tube was used (28.7±31.0μSv vs 38.2±44.2μSv, p =0.0739), especially during prolonged procedures such as CAs with spasm provocation test (31.6±38.5μSv vs 70.6±49.6μSv) or PCIs (29.1±34.6μSv vs 51±49.8μSv). However, fluoroscopic time was longer in the PCI group without the extension tube. Furthermore, the operator radiation exposure levels noted in our study were markedly lower than the levels described previously [7]. In fact, the levels noted with the radial approach were similar to those described in previous studies using the femoral approach [7]. Lange et al. [7] reported operator radiation exposure levels during CAs of 64±55μSv through the radial approach and 32±39μSv through the femoral approach, compared with 26.3±28.5μSv in our study. Similarly, operator radiation exposure during PCIs was 166±188μSv through the radial approach vs 110±115μSv through the femoral approach, compared with 44.07±44.08μSv in our study. This may be due to extensive operator experience in the radial approach in our centre (more than 1000 procedures for each operator) and the use of specific protection devices. As operator radiation exposure levels in our study were lower than expected, our study was probably underpowered to detect a difference between groups.

We believe that operator awareness of radiation exposure can be improved markedly by the use of electronic dosimeters placed both under the lead apron and on the left arm. These dosimeters deliver instant information on radiation exposure after the procedure. The operators can therefore improve their techniques to reduce exposure. In our study, a reduction in operator radiation exposure was noted throughout the trial: operator 1, 36.9μSv during the first month, 26.4μSv during the following two months; operator 2, 50μSv and 19μSv, respectively; operator 3, 39μSv and 33μSv, respectively (Figure 3). If we compare the radiation exposure during the first month of the study and the other two months for the three principal operators, there was a significant reduction in doses: 43.0±38.4μSv in the first month vs 25.8±25.9μSv in the other two months (p =0.0006).



Figure 3


Figure 3. 

Mean operator radiation exposure during the study.

Zoom

There are several limitations to our trial. First, the number of patients included was calculated using radiation exposure levels from previous studies. As the levels noted in our study were lower, our study was possibly undersized. Second, the extension tube was only effective during the acquisition of views because the operator had to manipulate the catheter without using the extension tube to place the catheter in the coronary arteries. Third, our results cannot be applied to all operators performing radial procedures, given the experience of our centre in this approach. Fourth, we did not use other devices that reduce operator radiation exposure, such as semiautomatic injection systems, three-dimensional acquisitions or a flat panel.

Conclusion

In this randomized study, we did not demonstrate a reduction in operator radiation exposure with the use of a 30cm extension tube. We cannot recommend its use in routine practice. However, a trend towards lower levels was shown in prolonged procedures such as PCIs and CAs with provocation test. No complications, such as air embolism, were noted. Operator radiation exposure levels were low compared with previous studies and decreased during the study with operator awareness, due to the use of electronic dosimeters under the lead apron and on the left arm. The use of exposed electronic dosimeters, which deliver instant information on the radiation exposure received during a procedure, could therefore be recommended to allow operators improve their protection techniques. Optimal use of protection devices and improvement of operator technique to reduce patient and operator radiation exposure must gain widespread acceptance by the interventional community and be part of the quality measures of an interventional cardiology programme.

Conflicts of interest

None.

References

Dill T., Deetjen A., Ekinci O., and al. Radiation dose exposure in multislice computed tomography of the coronaries in comparison with conventional coronary angiography Int J Cardiol 2008 ;  124 : 307-311 [cross-ref]
Einstein A.J., Henzlova M.J., Rajagopalan S. Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography JAMA 2007 ;  298 : 317-323 [cross-ref]
Valentin J. Avoidance of radiation injuries from medical interventional procedures Ann ICRP 2000 ;  30 : 7-67 [cross-ref]
Andreassi M.G., Cioppa A., Manfredi S., and al. Acute chromosomal DNA damage in human lymphocytes after radiation exposure in invasive cardiovascular procedures Eur Heart J 2007 ;  28 : 2195-2199 [cross-ref]
Kuon E., Glaser C., Dahm J.B. Effective techniques for reduction of radiation dosage to patients undergoing invasive cardiac procedures Br J Radiol 2003 ;  76 : 406-413 [cross-ref]
Brasselet C., Blanpain T., Tassan-Mangina S., and al. Comparison of operator radiation exposure with optimized radiation protection devices during coronary angiograms and ad hoc percutaneous coronary interventions by radial and femoral routes Eur Heart J 2008 ;  29 : 63-70
Lange H.W., von Boetticher H. Randomized comparison of operator radiation exposure during coronary angiography and intervention by radial or femoral approach Catheter Cardiovasc Interv 2006 ;  67 : 12-16 [cross-ref]
Cooper C.J., El-Shiekh R.A., Cohen D.J., and al. Effect of transradial access on quality of life and cost of cardiac catheterization: A randomized comparison Am Heart J 1999 ;  138 : 430-436 [cross-ref]
Geijer H., Persliden J. Radiation exposure and patient experience during percutaneous coronary intervention using radial and femoral artery access Eur Radiol 2004 ;  14 : 1674-1680
von Boetticher H., Meenen C., Lachmund J., and al. Radiation exposure to personnel in cardiac catheterization laboratories Z Med Phys 2003 ;  13 : 251-256
Larrazet F., Philippe F., Folliguet T., and al. Comparison between radial and femoral approaches in ad hoc coronary angioplasty Arch Mal Coeur Vaiss 2003 ;  96 : 175-180
Agostoni P., Biondi-Zoccai G.G., de Benedictis M.L., and al. Radial versus femoral approach for percutaneous coronary diagnostic and interventional procedures. Systematic overview and meta-analysis of randomized trials J Am Coll Cardiol 2004 ;  44 : 349-356 [cross-ref]
Kiemeneij F., Laarman G.J., Odekerken D., and al. A randomized comparison of percutaneous transluminal coronary angioplasty by the radial, brachial and femoral approaches: the access study J Am Coll Cardiol 1997 ;  29 : 1269-1275
Mann J.T., 3rd, Cubeddu G., Arrowood M. Operator radiation exposure in PTCA: comparison of radial and femoral approaches J Invasive Cardiol 1996 ;  8 (Suppl. D) : 22D-25D [cross-ref]



© 2009  Elsevier Masson SAS. All Rights Reserved.
EM-CONSULTE.COM is registrered at the CNIL, déclaration n° 1286925.
As per the Law relating to information storage and personal integrity, you have the right to oppose (art 26 of that law), access (art 34 of that law) and rectify (art 36 of that law) your personal data. You may thus request that your data, should it be inaccurate, incomplete, unclear, outdated, not be used or stored, be corrected, clarified, updated or deleted.
Personal information regarding our website's visitors, including their identity, is confidential.
The owners of this website hereby guarantee to respect the legal confidentiality conditions, applicable in France, and not to disclose this data to third parties.
Close
Article Outline