Reducing Radiation Exposure in the Electrophysiology Laboratory: It is More Than Just Fluoroscopy Times!

Results from a real-time dosimetry study during left atrial ablations performed with ultra-low dose radiation settings

Background

Three-dimensional mapping systems and the use of ultra-low dose radiation protocols have supported minimization of radiation dose during left atrial ablation procedures. By using optimal shielding, scattered radiation reaching the operator can be further reduced. This prospective study was designed to determine the remaining operator radiation exposure during left atrial catheter ablations using real-time dosimetry.

Methods

Radiation dose was recorded using real-time digital dosimetry badges outside the lead apron during 201 consecutive left atrial fibrillation ablation procedures. All procedures were performed using the same X‑ray system (Siemens Healthineers Artis dBc; Siemens Healthcare AG, Erlangen, Germany) programmed with ultra-low dose radiation settings including a low frame rate (two frames per second), maximum copper filtration, and an optimized detector dose. To reduce scattered radiation to the operators, table-suspended lead curtains, ceiling-suspended leaded plastic shields, and radiation-absorbing shields on the patient were positioned in an overlapping configuration.

Results

The 201 procedures included 139 (69%) pulmonary vein isolations (PVI) (20 cryoballoon ablations, 119 radiofrequency ablations, with 35 cases receiving additional ablation of the cavotricuspid isthmus) and 62 (31%) PVI plus further left atrial substrate ablation.

Mean radiation dose measured as dose area product for all procedures was 128.09 ± 187.87 cGy ∙ cm² with a mean fluoroscopy duration of 9.4 ± 8.7 min. Real-time dosimetry showed very low average operator doses of 0.52 ± 0.10 µSv. A subanalysis of 51 (25%) procedures showed that the radiation burden for the operator was highest during pulmonary vein angiography.

Conclusion

The use of ultra-low dose radiation protocols in combination with optimized shielding results in extremely low scattered radiation reaching the operator.

Comprehensive strategies to minimize radiation exposure during Interventional electrophysiology procedures: state-of-the-art review

INTRODUCTION

Cardiac electrophysiology (EP) procedures are frequently performed in patients with cardiac arrhythmias, chronic heart failure, and sudden cardiac death. Most EP procedures involve fluoroscopy, which results in radiation exposure to physicians, patients, and EP lab staff. Accumulated radiation exposure is a known health detriment to patients and physicians.

AREA COVERED

This review will summarize radiation exposure, dose metrics, complications of radiation exposure, factors affecting radiation exposure, minimizing radiation exposure, zero or near-zero fluoroscopy strategies, and up-to-date research in the area of reducing radiation exposure and best practices.

EXPERT COMMENTARY

Comprehensive strategies should be implemented in EP laboratories to minimize radiation exposure with standard fluoroscopy. There are routine techniques that can mitigate significant amounts of radiation exposure using standard equipment within the EP lab. The operators need to emphasize that EP practices routinely incorporate non-ionizing radiation sources for cardiac imaging (e.g. magnetic resonance imaging, advanced electroanatomical mapping systems, intracardiac ultrasonography) in addition to other novel technologies to mitigate radiation exposure to patients and physicians.

What factors affect fluoroscopy use during Bernese periacetabular osteotomy for acetabular dysplasia?

Periacetabular osteotomy (PAO) is the treatment of choice for acetabular dysplasia in the skeletally mature. Little is known about factors affecting fluoroscopy use in PAO. Therefore, we strived to determine patient and surgery factors are associated with the amount of fluoroscopy time and radiation dose during PAO. We performed a retrospective review of 378 patients who underwent PAO between January 2012 and August 2017. The mean age was 21.7 years and 326 (86%) were females. A total of 85 patients underwent concomitant arthroscopy and 60 underwent open arthrotomy. We recorded fluoroscopy time in minutes and radiation dose area product (DAP) in mGy·m². Multivariate general linear modeling identified independent predictors of fluoroscopy time and radiation dose. Mean fluoroscopy time was 1.21 minutes and mean fluoroscopy DAP was 0.71 mGy·m². Multivariate predictors of increased fluoroscopy time were male gender (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Multivariate predictors of increased fluoroscopy DAP were increased body mass index (BMI) (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Patients undergoing hip arthroscopy concomitant to PAO are at higher risk of longer fluoroscopy time and higher radiation dose. Other factors affecting fluoroscopy time included male gender and surgeon, while radiation dose was further affected by surgeon and BMI. Our findings can facilitate discussion about the risk of radiation exposure during PAO.

Physicians' exposure to radiation during electrophysiology procedures

PURPOSE

Cardiologists are among the health professionals that are most exposed to ionizing radiation, but there is no study comparing the level of exposure of physicians during different electrophysiology procedures. We aimed to measure and compare cardiologists' exposure to radiation during different electrophysiology procedures.

METHODS

The study population comprised all electrophysiology procedures performed over a 6-month period in a large referral centre. The endpoint was operator radiation exposure, assessed using a personal electronic dosimeter located on the operator's left arm.

RESULTS

In total, 150 electrophysiology procedures were analyzed. Compared with electrophysiology studies (reference category), physician radiation exposure was 3-fold greater during ablation of atrial fibrillation, 9-fold greater during ablation of atrioventricular nodal reentrant tachycardia (AVNRT)/atrioventricular reentrant tachycardia (AVNT), and 10-fold greater during ablation of atrial flutter (p < 0.001). Physician exposure was mainly related to X-ray time (R² = 0.28).

CONCLUSIONS

Our study showed significant differences in cardiologists' exposure to ionizing radiation depending on the type of electrophysiology procedure. Atrial flutter and AVNRT/AVNT ablations are the procedures in which operators are most exposed to ionizing radiation.

Fluoroscopy integrating technology in a 3D mapping system during ablation of atrial arrhythmias: first experiences

INTRODUCTION

Ablation of the cavotricuspid isthmus (CTI) in patients with atrial flutter (AFL) and pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) are both common therapies. As the demand for ablative treatments rises, total radiation exposure times of staff increase concomitantly. Here, we report on our first experiences with a new fluoroscopy integrating system (FIS) integrated into a current 3D mapping system (3DMS).

MATERIAL AND METHODS

The study population consisted of 59 consecutive patients who underwent PVI or CTI ablation (26 and 33 patients with and without FIS respectively). Total procedure time (PT), fluoroscopy exposure time (FT) and dose-area product (DAP) were monitored.

RESULTS

All procedures were successfully completed without major complications. Employing FIS in the PVI group, FT and DAP were both significantly reduced after completing a short learning curve of 6 cases (respectively 361.6 ±181 s vs. 530.3 ±156.7 s, p = 0.039; 801.9 ±439.15 cGycm² vs. 1495 ±435.2 cGycm², p = 0.002). Mean PT was not significantly affected (121 ±26.7 min vs. 135.6 ±23.2 min, p = 0.21). The same holds true for CTI ablation: FT (99.29 ±51.4 s vs. 153.9 ±76.6 s, p = 0.022) and DAP (269 ±128.7 cGycm² vs. 524.3 ±288.4 cGycm², p = 0.002) were significantly reduced, leaving PT not significantly affected (29.5 ±10 min vs. 35.2 ±16.3 min, p = 0.23).

CONCLUSIONS

The introduction of the new FIS with a current 3DMS results in a significant reduction of both the total FT and DAP without affecting PT. The initial learning curve for adopting this method is considerably short.

Is There a Relationship Between Body Mass Index and Fluoroscopy Time During Cervical Interlaminar Epidural Steroid Injections?

Background

The challenge of obtaining medical imaging in individuals with higher body mass index (BMI) is described, but there is minimal data regarding the relationship between BMI and fluoroscopy time during cervical interlaminar epidural steroid injection (CIESI).

Objective

To determine the relationship between BMI and fluoroscopy time during CIESI.

Methods

Retrospective cohort study of patients who underwent fluoroscopically guided CIESI between January 2014 and February 2015 at an academic pain medicine center. Fluoroscopy time data were collected. Comparisons based on analysis of variance were made between patients with normal (<25.0 kg/m 2 ), overweight (25.0-29.9 kg/m 2 ), and obese (≥30.0 kg/m 2 ) BMI.

Results

Of 399 procedure encounters, 366 had documented BMI and fluoroscopy time data and were included for analysis. Mean age (± SD) in this cohort was 53 ± 13 years, including 189 females (52%) and 205 first-time injections. Mean fluoroscopy time for all injections was 18 ± 10 seconds. Separated by categorical BMI class, the mean fluoroscopy time was 18 ± 9 seconds for normal weight patients, 17 ± 10 seconds for overweight patients, and 20 ± 11 seconds for obese patients, respectively. Post hoc analysis showed that fluoroscopy time was significantly longer only in obese compared with overweight patients ( P  = 0.02). Trainee involvement and first-time vs repeat injection did not significantly alter fluoroscopy time ( P  = 0.17 and P  = 0.12, respectively).

Conclusions

The findings of this study indicate that BMI does not appear to have a clinically significant impact on fluoroscopy time during cervical interlaminar epidural steroid injection procedures. Future study is needed to directly quantify radiation exposure in patients and practitioners, as well as the associated health risk.

Important reduction of the radiation dose for pulmonary vein isolation using a multimodal approach

Aims

The number of pulmonary vein isolation (PVI) ablation procedures is steadily increasing worldwide resulting in a substantial radiation exposure to patients and operators. The aim of our study was to reduce radiation exposure during these procedures to a critical amount without compromising patient safety.

Methods and results

First, we assessed radiation exposure for primary PVI procedures over time (2005-2015) at the University Heart Center Freiburg-Bad Krozingen. Second, we prospectively evaluated in 52 patients, the efficacy and safety of a novel radiation reduction program (particularly applying an enhanced fluoroscopy pulse dose-reduction and optimized 3D-mapping system use). In 2035 primary PVI procedures, radiation exposure, assessed as estimated effective dose (eED in mSv, dose area product * 0.002 * conversion factor for females), fluoroscopy-time, and procedure-time decreased significantly from 2005 to 2015 (e.g. eED decreased from 9.3 (interquartile range (IQR) 6.4-13.4) mSv to 0.9 (IQR 0.5-1.6) mSv, p for trend <0.001). Importantly, application of the enhanced radiation reduction program further reduced eED to 0.4 mSv (IQR 0.3-0.6, P < 0.001 vs. control), a value not significantly different from slow-pathway ablation procedures (P = 0.41). Multiple linear regression analysis identified the radiation reduction program as the only independent variable associated with a decrease in radiation exposure.

Conclusion

Radiation exposure during PVI decreased over the last decade and can further be reduced significantly by the implementation of an enhanced radiation reduction program.

Reducing radiation exposure during procedures performed in the electrophysiology laboratory

INTRODUCTION

Expert societies recently published strong recommendations to reduce the exposure of patients and staff to ionizing radiation (IR) during interventional and electrophysiology (EP) procedures. However, adherence to these guidelines remains difficult and the impact of implementing such recommendations is poorly characterized.

METHODS AND RESULTS

We conducted a single-center cohort study to quantify radiation exposure over time in three EP laboratories at the Montreal Heart Institute during 5,546 consecutive procedures from 2012 to 2015 by 11 primary operators. Overall, 2,618 (47.2%) procedures were catheter-based and 2,928 (52.8%) were device interventions. Interventions to reduce radiation exposure included educational initiatives to raise awareness (i.e., limiting cine acquisition, patient position, table height), slower frame rate, lower radiation dose per pulse, collimation, and integration with 3-D mapping systems and/or MediGuide technology. An 85% reduction in IR exposure was observed from 2012 to 2015, with the mean dose-area-product (DAP) decreasing from 7.65 ± 0.05 Gy·cm² to 1.15 ± 0.04 Gy·cm² (P < 0.001). This was true for catheter-based procedures (mean DAP 16.99 ± 0.08 to 2.00 ± 0.06 Gy·cm² , P < 0.001) and device interventions (mean DAP 4.18 ± 0.06 to 0.64 ± 0.05 Gy·cm² , P < 0.001). The median effective dose of IR recorded per quarter by 282 cervical dosimeters on EP staff decreased from 0.57 (IQR 0.18, 1.03) mSv in 2012 to 0.00 (IQR 0.00, 0.19) mSv in 2015, P < 0.001.

CONCLUSION

Enforcing good clinical practices with simple measures and low-dose fluoroscopy settings are highly effective in reducing IR exposure in the EP lab. These promising results should encourage other EP labs to adopt similar protective measures.

Safety and efficacy of applying a low-dose radiation fluoroscopy protocol in device implantations

Aims

For cardiac implantable electronic device (CIED) implantations, visualization of lead placement is necessary and fluoroscopy remains by far the most commonly used technique. With simple changes in the X-ray system settings, total radiation dose can be reduced significantly. The purpose of this study was to assess the safety and efficacy of various CIED implantations performed after implementation of a new dose reduction protocol (DRP).

Methods and results

We conducted a retrospective chart review of 584 patients undergoing CIED implantation or revision in our hospital. Of these patients, 280 (48%) underwent the implantation prior to and 304 (52%) after the DRP introduction. The DRP included various changes for optimized image processing and exposure system settings to enable dose reduction, as well as a reduced frame rates (4 FPS for fluoroscopy and 7.5 FPS for cinematographic images). Of the 584 patients, 53 (9.1%) had a one-chamber pacemaker, 232 (39.7%) a two-chamber pacemaker, 133 (22.8%) a one-chamber ICD, 35 (6.0%) a two-chamber ICD, 82 (14.0%) a CRT (de novo) implantation, and 49 (8.3%) had an upgrade to a CRT device. DRP was associated with a 64% reduction of the dose-area product (1372 ± 2659 vs. 3792 ± 5025 cGcm2, P < 0.001), while fluoroscopy duration (13 ± 15 vs. 13 ± 15 min) and procedural duration (93 ± 52 vs. 92 ± 52 min.) did not significantly increase. Complication rates did not differ significantly between the two groups.

Conclusion

The DRP proved to effectively reduce radiation dose for all types of CIED implantations. Fluoroscopy time, total procedure time, and the number of complications did not increase after introducing the DRP.

Evaluation and Management of Maternal Cardiac Arrhythmias

Pregnant women often complain of palpitations. The differential diagnosis for new-onset palpitations in pregnancy ranges from benign conditions to life-threatening arrhythmias. Maternal arrhythmias can occur in isolation or in the setting of underlying structural heart disease. Optimal management of maternal cardiac arrhythmias includes identification of the specific arrhythmia, diagnosis of comorbid conditions, and appropriate intervention. In general, management of maternal cardiac arrhythmias is similar to that of the general population. Special consideration must be given as to the effects of medications and procedures on both the mother and fetus to optimize outcomes. The importance of multidisciplinary care with cardiology, obstetrics, and anesthesia is emphasized.

Reduction of Fluoroscopy Time and Radiation Dosage During Catheter Ablation for Atrial Fibrillation

Radiofrequency catheter ablation has become the treatment of choice for atrial fibrillation (AF) that does not respond to antiarrhythmic drug therapy. During the procedure, fluoroscopy imaging is still considered essential to visualise catheters in real-time. However, radiation is often ignored by physicians since it is invisible and the long-term risks are underestimated. In this respect, it must be emphasised that radiation exposure has various potentially harmful effects, such as acute skin injury, malignancies and genetic disease, both to patients and physicians. For this reason, every electrophysiologist should be aware of the problem and should learn how to decrease radiation exposure by both changing the setting of the system and using complementary imaging technologies. In this review, we aim to discuss the basics of X-ray exposure and suggest practical instructions for how to reduce radiation dosage during AF ablation procedures.

The effect of body mass index on fluoroscopic time and radiation dose during lumbar transforaminal epidural steroid injections

OBJECTIVE

Transforaminal epidural steroid injections (TFESIs) are a commonly used, effective treatment for radicular pain. Accurate delivery of the injected medication helps to ensure maximum therapeutic efficacy and to decrease possible adverse events, and fluoroscopy is the preferred and most common image-guidance modality used to ensure accurate needle placement during lumbar TFESIs. However, fluoroscopic-guided lumbar TFESIs put patients at risk because of radiation exposure. The purpose of this study was to determine the relationship between body mass index (BMI) and fluoroscopy time and radiation dose during lumbar TFESIs.

DESIGN

A retrospective study design was used.

SETTING

The study was conducted at an academic orthopedic center. All procedures were performed by physicians board-certified in Physical Medicine and Rehabilitation (PM&R) and with subspecialty certification in sports medicine, or by a trainee under close supervision from an attending physician.

PARTICIPANTS

Participants were patients who underwent fluoroscopic-guided lumbar TFESIs between February 2013 and March 2015 with a documented height/weight, fluoroscopy time, and radiation dose.

INTERVENTIONS

All patients received unilateral or bilateral lumbar TFESIs with fluoroscopic guidance. Fluoroscopy time and dose were recorded.

MAIN OUTCOME MEASURES

The main outcome measures were fluoroscopy time and radiation dose. A Bonferroni correction was implemented for multiple comparisons, defining statistical significance at p<.01.

RESULTS

A total of 2,443 injections were performed on 1,548 patients. There were 419 normal, 572 overweight, and 557 obese patients, respectively. There were 1,426 first-time injections and 1,017 repeat injections. Sixty-nine percent (1,681) were unilateral injections, and 26.4% (645) were single level injections. A trainee was involved in 1,361 (55.7%) of the injections performed. The mean fluoroscopy time for all injections was 30.0±17.5 seconds, and the mean radiation dose was 2,164±1,484 mGy-cm(2). The mean fluoroscopy time was 27.7±15.2 seconds for normal weight patients, 30.0±21.0 seconds for overweight patients, and 32.2±15.1 seconds for obese patients, showing a significant difference between groups (p<.001). The mean radiation doses for each group were 1,376±450, 1,911±653, and 3,029±640 mGy-cm(2), respectively, with a significant increase in radiation dose with increasing BMI (p<.001).

CONCLUSIONS

The findings of this study demonstrate that fluoroscopy radiation dose and fluoroscopy time during lumbar TFESIs are increased in patients with an elevated BMI, and in patients of greater age, but the presence of a trainee had no effect on fluoroscopy time.

Reduction of Fluoroscopic Exposure Using a New Fluoroscopy Integrating Technology in a 3D-Mapping System During Pulmonary Vein Isolation With a Circular Multipolar Irrigated Catheter

Pulmonary vein isolation (PVI) is a cornerstone therapy in patients with atrial fibrillation (AF). With increasing numbers of PVI procedures, demand arises to reduce the cumulative fluoroscopic radiation exposure for both the physician and the patient. New technologies are emerging to address this issue. Here, we report our first experiences with a new fluoroscopy integrating technology in addition to a current 3D-mapping system. The new fluoroscopy integrating system (FIS) with 3D-mapping was used prospectively in 15 patients with AF. Control PVI cases (n = 37) were collected retrospectively as a complete series. Total procedure time (skin to skin), fluoroscopic time, and dose-area-product (DAP) data were analyzed. All PVI procedures were performed by one experienced physician using a commercially available circular multipolar irrigated ablation catheter. All PVI procedures were successfully undertaken without major complications. Baseline characteristics of the two groups showed no significant differences. In the group using the FIS, the fluoroscopic time and DAP were significantly reduced from 571 ± 187 seconds versus 1011 ± 527 seconds (P = 0.0029) and 4342 ± 2073 cGycm(2) versus 6208 ± 3314 cGycm(2) (P = 0.049), respectively. Mean procedure time was not significantly affected and was 114 ± 31 minutes versus 104 ± 24 minutes (P = 0.23) by the FIS.The use of the new FIS with the current 3D-mapping system enables a significant reduction of the total fluoroscopy time and DAP compared to the previous combination of 3D-mapping system plus normal fluoroscopy during PVI utilizing a circular multipolar irrigated ablation catheter. However, the concomitant total procedure time is not affected. Thus, the new system reduces the radiation exposure for both the physicians and patients.

Evaluation of a new very low dose imaging protocol: feasibility and impact on X-ray dose levels in electrophysiology procedures

Aims

This study presents and evaluates the impact of a new lowest-dose fluoroscopy protocol (Siemens AG), especially designed for electrophysiology (EP) procedures, on X-ray dose levels.

Methods and results

From October 2014 to March 2015, 140 patients underwent an EP study on an Artis zee angiography system. The standard low-dose protocol was operated at 23 nGy (fluoroscopy) and at 120 nGy (cine-loop), the new lowest-dose protocol was operated at 8 nGy (fluoroscopy) and at 36 nGy (cine-loop). Procedural data, X-ray times, and doses were analysed in 100 complex left atrial and in 40 standard EP procedures. The resulting dose–area products were 877.9 ± 624.7 µGym² (n = 50 complex procedures, standard low dose), 199 ± 159.6 µGym² (n = 50 complex procedures, lowest dose), 387.7 ± 36.0 µGym² (n = 20 standard procedures, standard low dose), and 90.7 ± 62.3 µGym² (n = 20 standard procedures, lowest dose), P < 0.01. In the low-dose and lowest-dose groups, procedure times were 132.6 ± 35.7 vs. 126.7 ± 34.7 min (P = 0.40, complex procedures) and 72.3 ± 20.9 vs. 85.2 ± 44.1 min (P = 0.24, standard procedures), radiofrequency (RF) times were 53.8 ± 26.1 vs. 50.4 ± 29.4 min (P = 0.54, complex procedures) and 10.1 ± 9.9 vs. 12.2 ± 14.7 min (P = 0.60, standard procedures). One complication occurred in the standard low-dose and lowest-dose groups (P = 1.0).

Conclusion

The new lowest-dose imaging protocol reduces X-ray dose levels by 77% compared with the currently available standard low-dose protocol. From an operator standpoint, lowest X-ray dose levels create a different, reduced image quality. The new image quality did not significantly affect procedure or RF times and did not result in higher complication rates. Regarding radiological protection, operating at lowest-dose settings should become standard in EP procedures.