Patient and staff radiation dosimetry during cardiac electrophysiology studies and catheter ablation procedures: a comprehensive analysis

Zero-fluoro atrioventricular-nodal reentrant tachycardia ablation

BACKGROUND

Atrioventricular-nodal reentrant tachycardia (AVNRT) is a common supraventricular tachycardia, particularly in younger patients. The treatment of choice is radiofrequency catheter ablation (RFCA), traditionally necessitating ionizing radiation for catheter guidance.

OBJECTIVE

The authors aimed to demonstrate the feasibility and safety of zero-fluoroscopy RFCA of AVNRT using EnSite™ NavX™ as a three-dimensional (3D) electroanatomical mapping system (EAM).

METHODS

The authors retrospectively analyzed 68 patients that underwent AVNRT-RFCA. One group was a priori allocated to conventional fluoroscopy mapping (convFluoro, n = 30). In 38 cases, the electrophysiologist chose to use 3D-EAM for ablation. Of these patients, 20 could be ablated without fluoroscopy use (zeroFluoro). In 18 cases that were initially intended as 3D-EAM, additional fluoroscopy use was necessary due to difficult anatomic conditions (convertedFluoro). Procedure duration, fluoroscopy duration and dose, as well as complications were analyzed.

RESULTS

Procedure duration was similar for the convFluoro and zeroFluoro groups (74 ± 24 min vs. 80 ± 26 min, p = ns). The convertedFluoro group showed longer procedure duration compared to the convFluoro group (94 ± 30 min vs. 74 ± 24 min, p < 0.05). The use of 3D-EAM significantly reduced fluoroscopy duration comparing the convFluoro with the convertedFluoro group (12 ± 9 min vs. 7 ± 6 min, p < 0.05). The difference in fluoroscopy dose between convFluoro and convertedFluoro did not reach significance (169 ± 166 cGycm2 vs. 134 ± 137 cGycm2, p = ns). In zeroFluoro cases, no radiation was used at all. 3D-EAM-guided RFCA was primarily successful in all patients. Overall, there were only few minor complications in the different groups. No major complications occurred.

CONCLUSION

Zero-fluoro RFCA in patients with AVNRT is feasible and safe. 3D-EAM can reduce radiation exposure in the majority of patients without prolonging procedure duration or increasing complications.

2023 HRS expert consensus statement on the management of arrhythmias during pregnancy

This international multidisciplinary expert consensus statement is intended to provide comprehensive guidance that can be referenced at the point of care to cardiac electrophysiologists, cardiologists, and other health care professionals, on the management of cardiac arrhythmias in pregnant patients and in fetuses. This document covers general concepts related to arrhythmias, including both brady- and tachyarrhythmias, in both the patient and the fetus during pregnancy. Recommendations are provided for optimal approaches to diagnosis and evaluation of arrhythmias; selection of invasive and noninvasive options for treatment of arrhythmias; and disease- and patient-specific considerations when risk stratifying, diagnosing, and treating arrhythmias in pregnant patients and fetuses. Gaps in knowledge and new directions for future research are also identified.

Proposing national diagnostic reference levels for electrophysiology studies and catheter ablation procedures in Bulgaria

INTRODUCTION

The implementation of diagnostic reference levels (DRLs) is an essential tool for optimisation of the routine practice, better management of patient exposure while maintaining sufficient image quality. National DRLs for electrophysiology (EP) procedures are not available in our country.

PURPOSE

The main purpose of the study was to propose, for first time in Bulgaria, national DRLs (NDRLs) for EP studies and ablation procedures of two different levels of complexity. The proposed DRLs can be later used to establish NDRLs by the national authority with regulatory functions related to medical exposure.

METHOD

A retrospective study was done with the three highest volume Bulgarian EP centers, where over 95% of all cardiac ablations were performed. Data were extracted from the electronic registry for invasive electrophysiology BG-EPHY. Independently of the proposed NDRLs, we also compared the air kerma-area product (KAP) between the participating centers for procedures of the same level of complexity.

RESULTS

The proposed NDRL in terms of KAP were: 5.2 Gy.cm2 for diagnostic EP studies, 25.5 Gy.cm2 for simple ablations, and 52.1 Gy.cm2 for complex ablations. There was a significant variation in KAP for procedures with the same degree of complexity within each center.

CONCLUSION

This study is the first to propose NDLRs for EP studies and ablation procedures of two levels of complexity in Bulgaria. The results identified EP procedures requiring further optimization of patient protection and provided a basis for future comparisons and standardization with further investigations on the topic. The proposed NDRLs are recommended to be used for better management of radiation exposure during EP procedures of different levels of complexity.

Risk of ionizing radiation in pregnancy: just a myth or a real concern?

There are natural concerns regarding the risks posed to the foetus by ionizing radiation exposure during pregnancy. Therefore, many female physicians select to avoid working in an environment associated with ionizing radiation exposure like the catheterization laboratory and even exclude training as electrophysiology, interventional cardiologists, or radiologists. For those already working in this field, pregnancy involves usually a 1-year interruption (pregnancy and maternity leave) to their careers, leading at times to delays in the decision to become pregnant. This review describes the low added risk of malformation/cancer in the offspring, highlight gaps in our understanding, discuss several common wrong beliefs, and recommend how to further decrease radiation dose, especially during pregnancy.

[Electromagnetic interference in 3D-mapping procedures]

Catheter-based ablation is nowadays a safe and widespread procedure for the treatment of cardiac arrhythmia. This requires exact anatomical knowledge both before and during the examination and is an important prerequisite for targeted treatment. At the beginning of the era of interventional catheter-based treatment, fluoroscopy was the only and usual means of visualization, whereas in the middle of the 1990s continuous 3D-mapping systems were developed for the non-fluoroscopic examination of patients. The correct use of these 3‑D systems, which non-fluoroscopically visualize the catheter and mostly identify mechanisms of arrhythmia in great detail, nowadays makes an important contribution to successful interventional catheter treatment of arrhythmia; however, it is not uncommon for patients with ventricular arrhythmia to also carry implanted electronic devices, such as pacemakers, defibrillators or less frequently left ventricular hemodynamic support systems. All implantable devices lead to electromagnetic interferences, which can complicate the diagnostics and treatment during electrophysiological examinations and ablation. This article addresses the adversities and experiences associated with magnet-based 3D systems and implantable electromagnetically active cardiac devices.

Outcome of video-assisted thoracoscopic implantation of epicardial left ventricular leads with visual targeting for cardiac resynchronization therapy

OBJECTIVES

Our goal was to analyse the implantation and outcome of thoracoscopic epicardial leads after a failed endovascular approach or follow-up (FU) complications after endovascular implantation.

METHODS

We reviewed the records of patients with failed endovascular left ventricular (LV) lead placement or complications during FU, who were subsequently referred to cardiac surgeons for treatment with thoracoscopic LV lead implantation. We analysed the reasons for endovascular failure; the indications for the surgical procedures; and the clinical, echocardiographic and device FU results.

RESULTS

Between 2010 and 2013, a total of 23 patients were included. Among them, 17 of the patients had no previous cardiothoracic surgery, 13 (76%) had successful video-assisted thoracoscopy (VAT) LV lead implantation, 3 (18%) had a conversion to thoracotomy and 1 (6%) failed. Of the 6 patients with prior cardiothoracic surgery, 2 (33%) had VAT only, 3 (50%) had primary thoracotomies and 1 (17%) had a conversion. Two major complications occurred. The reasons for LV endovascular lead failure were subclavian vein occlusion (n = 2), implant failure (n = 13) and complications during the FU period (n = 8). FU information was available for 20 patients: 17 (85%) had improved symptoms. The median FU period was 33 months. A total of 78% of patients were in New York Heart Association (NYHA) functional class III-IV before the operation; 30% were in NYHA functional class III-IV at the last FU examination. The left ventricular ejection fraction increased from 25% before surgery to 31% at the last FU examination. Overall, sensing and pacing threshold values remained stable over time. In 1 patient, lead revision was necessary due to an increase in the pacing threshold.

CONCLUSIONS

VAT implantation of LV leads had an excellent response rate with an improvement in NYHA functional class and left ventricular ejection fraction. The lead measurements were mainly stable over time.

Strategies to Reduce Radiation Exposure in Electrophysiology and Interventional Cardiology

Clinical diagnosis sometimes involves the use of medical instruments that employ ionizing radiation. However, ionizing radiation exposure is a workplace hazard that goes undetected and is detrimental to patients and staff in the catheterization laboratory. Every possible effort should be made to reduce the amount of radiation, including scattered radiation. Implementing radiation dose feedback may have a role in reducing exposure. In medicine, it is important to estimate the potential biologic effects on, and the risk to, an individual. In general, implantation of cardiac resynchronization devices is associated with one of the highest operator exposure doses due to the proximity of the operator to the radiation source. All physicians should work on the principle of as low as reasonably achievable. Methods for reducing radiation exposure must be implemented in the catheterization laboratory. In this article, we review the available tools to lower the radiation exposure dose to the operator during diagnostic, interventional, and electrophysiological cardiac procedures.

Evaluation of a new ultralow-dose radiation protocol for electrophysiological device implantation: A near-zero fluoroscopy approach for device implantation

BACKGROUND

Radiation is one of the main hazards of electrophysiological device implantation, and insertion of cardiac resynchronization therapy (CRT) devices in particular is associated with high radiation doses.

OBJECTIVE

The purpose of this study was to evaluate the impact of a new ultralow-dose radiation protocol on radiation doses, success rate, and safety of electrophysiological device implantations.

METHODS

In 2018, we established a new ultralow-dose radiation protocol (reduced pulse width, increased thickness of minimum copper filters, reduced detector entrance dose, reduced pulse rate, optimized image postprocessing settings) for de novo device implantation at our hospital. A total of 1173 patients (11% single-chamber devices, 69% dual-chamber devices, 20% CRT devices) were analyzed. Five hundred twelve patients (44%) in the ultralow-dose group were compared to 661 patients (66%) treated during 2017 with a conventional low-dose protocol.

RESULTS

With the ultralow-dose radiation protocol, effective doses could be reduced by 59% (median 0.25 [interquartile range: 0.11-0.63] vs median 0.10 [interquartile range: 0.03-0.28] mSv; P <.0001) per procedure without a significant change in procedure time (P = .5). This dose reduction could be achieved without decreasing procedure success (P = 1) or increasing complication rate (P = .8). Male gender, higher body mass index, increased procedure and fluoroscopy times, and use of the conventional radiation protocol were independent predictors of higher radiation doses in multivariate regression analysis.

CONCLUSION

By establishing a new ultralow-dose radiation protocol, we could significantly decrease radiation exposure, reaching the lowest radiation doses for electrophysiological device implantation reported to date.

Electroanatomic mapping-guided pediatric catheter ablation with limited/zero fluoroscopy

Objective:

The use of fluoroscopy in pediatric catheter ablation has decreased because of mapping systems. In this study, we present the efficiency and reliability of the electroanatomic mapping system in nonfluoroscopic pediatric catheter ablation.

Methods:

The medical records of patients aged <18 years who underwent ablation between November 2016 and April 2018 were evaluated. Fluoroscopy was not used in cases involving ablation of right sided-arrhythmia foci. Fluoroscopy was used only for trans-septal puncture or retroaortic approach/coronary angiography.

Results:

A total of 76 patients underwent catheter ablation for 78 supraventricular and ventricular tachyarrhythmia substrates under the guidance of EnSite Velocity system. Fluoroscopy was used in only 14 (18.4%) of these substrates. The mean fluoroscopy duration in these 14 procedures was 5.4±3.15 min. No complications were noted, except a temporary right bundle branch block in one patient and pericardial effusion in another following cryoablation. The acute success rate in achieving complete elimination of arrhythmia substrates was 97.4% (76/78). The recurrence rate was 5.1% (4/78) at follow-up.

Conclusion:

Fluoroscopy can be completely eliminated in most pediatric catheter ablation procedures with the use of mapping systems by achieving high acute success rates and acceptable low complication rates.

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.

Transseptal Puncture for Catheter Ablation in Children

Transseptal puncture (TP) is used in pediatric patients to access the left atrium in left-sided arrhythmia catheter ablation. Performing this procedure can be difficult and risky, especially in small children. In this study, we aimed to evaluate the safety and feasibility of TPs in children ≤ 30 kg. Between April 2012 and April 2018, a retrospective evaluation was conducted of the clinical features, procedural outcomes, and follow-ups of ≤ 30 kg pediatric patients who required TPs for left-sided ablations at a pediatric electrophysiology center in which a three-dimensional mapping system was routinely used. A total of 45 pediatric patients who were ≤ 30 kg, underwent TPs: 10 patients ≤ 20 kg (Group 1) and 35 patients > 20 kg and ≤ 30 kg (Group 2). The TP success rate was 97.8%. The median procedure and fluoroscopy times were 120 min and 5.43 min, respectively. One patient developed self-limited pericardial effusion during the procedure; however, there were no incidences of cardiac tamponade. There was no significant difference between the two groups in terms of the procedure time and fluoroscopy time, and pericardial effusion was only observed in Group 2. TPs are safe and feasible in small children. These procedures can be performed with low complication rates in children weighing ≤ 30 kg.

Catheter ablation for supraventricular tachycardia in children ≤ 20 kg using an electroanatomical system

PURPOSE

Catheter ablation is the only choice of treatment in some small children with medically refractory supraventricular tachycardia (SVT). Electroanatomical mapping systems (EMS) are more commonly utilized in electrophysiological procedures in recent years, which resulted in a significant decrease in fluoroscopy exposure. The potential benefit of EMS in small children has not been studied. Therefore, we investigated the outcomes of children undergoing catheter ablation weighing ≤ 20 kg using an electroanatomical mapping system.

METHODS

This study evaluated the outcomes, characteristics, and follow-ups of children ≤ 20 kg who underwent SVT ablations between April 2012 and April 2018 in a pediatric electrophysiology center where EMS were routinely used.

RESULTS

In a 6-year period, 1129 children underwent SVT catheter ablation under EMS guidance at our institution. A total of 84 of them were weighing ≤ 20 kg. The acute success rate was 97.6% in 85 tachycardia substrates. No fluoroscopy was used in 58 of the patients, while a median of 5 (4-14) min of fluoroscopy was used in the remaining 26 patients. Recurrences were seen in 4 patients (4.8%) at a mean follow-up of 3.89 ± 2.08 years. Five patients developed non-vital complications (2 right bundle block and 3 temporary complete block that spontaneously resolved during the procedure).

CONCLUSIONS

The outcome of catheter ablation with the guidance of EMS for the treatment of SVT in small children is favorable. Fluoroscopy exposure can be decreased and even eliminated in most patients.

Pattern and degree of radiation exposure during endovascular surgery performed using a mobile C-arm or in a hybrid room

Purpose

A prospective study was conducted to compare radiation exposure to different parts of an endovascular surgeon's body when using a mobile C-arm with that in a hybrid room.

Methods

Exposure during individual procedures performed on 39 patients with a mobile C-arm and 42 patients in a hybrid room, from July 2016 to December 2016, was evaluated.

Results

The procedures performed, fluoroscopy time, and dose-area product were not significantly different between groups. The dose-area product per second in the hybrid room group appeared greater than in the C-arm group (4.5 µGym²/sec vs. 3.1 µGym²/sec). In the C-arm group, the peak skin dose on the right neck (1.77 mSv) and shoulder (1.48 mSv) appeared higher than those on their left side (0.32 mSv, 0.53 mSv, respectively) and the counterparts of the hybrid room group (0.88 mSv, 0.20 mSv, respectively).

Conclusion

The peak skin dose in the hybrid room appeared highest for the lower part of the protective apron. The dose-area product per second seemed to be greater in the hybrid room than when using the C-arm. Thus, attention should be focused on protecting the surgeon's upper body when using the C-arm and the lower body when using the hybrid room.

Patient Exposure during Fluoroscopy-guided Pacemaker Implantation Procedures

A pacemaker, which is used for heart resynchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of pacemaker implantation procedures has increased to more than 50% worldwide. During this procedure, patients can be exposed to excessive radiation exposure. Wide range of doses has been reported in previous studies, suggesting that optimization of this procedure has not been fulfilled yet. The current study evaluated patient radiation exposure during cardiac pacemaker procedures and quantified the patient effective dose. A total of 145 procedures were performed for five pacemaker procedures (VVI, VVIR, VVD, VVDR, and DDDR) at two hospitals. Patient doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from the National Radiological Protection Board (NRPB, now The Health Protection Agency). The effective dose values were used to estimate cancer risk from the pacemaker procedure. Patient demographic data and exposure parameters for fluoroscopy and radiography were quantified. The mean patient doses ± SD per procedure (Gycm²) for VVI, VVIR, VVD, VVDR, and DDDR were 1.52 ± 0.13 (1.43-1.61), 3.28 ± 2.34 (0.29-8.73), 3.04 ± 1.67 (1.57-4.86), 6.04 ± 2.326 3.29-8.58), and 8.8 ± 3.6 (4.5-26.20), respectively. The overall patient effective dose was 1.1mSv per procedure. It is obvious that the DDDR procedure exposed patients to the highest radiation dose. Patient dose variation can be attributed to procedure type, exposure parameter settings, and fluoroscopy time. The results of this study showed that patient doses during different pacemaker procedures are lower compared to previous reported values. Patient risk from pacemaker procedure is low, compared to other cardiac interventional procedures. Patients' exposures were mainly influenced by the type of procedures and the clinical indication.

The Amigo™ Remote Catheter System: From Concept to Bedside

Radiation exposure is a serious concern during fluoroscopic procedures, including electrophysiology (EP) studies and radiofrequency catheter ablation of arrhythmias. Operators typically don lead aprons to protect themselves from radiation, but wearing lead can result in greater fatigue and orthopedic injury during long procedures. To address this problem, two robotic catheter systems (RCS) have previously been introduced on the market, the Niobe^® (Stereotaxis Inc., St. Louis, MO, USA) and Sensei^® X (Hansen Medical, Inc., Mountain View, CA, USA) systems. However, the widespread adoption of these systems has been limited by both cost and ease of use. In contrast, the Amigo™ RCS (Catheter Precision, Inc., Mount Olive, NJ, USA) was developed to provide a simple, lower profile, and less expensive remote catheter manipulation solution. Approved by the United States Food and Drug Administration (FDA), this technology allows for operators to remotely manipulate electrophysiology (EP) catheters from outside the fluoroscopy field. Notably, the Amigo™ RCS (Catheter Precision, Inc., Mount Olive, NJ, USA) first underwent an early study in dogs in 2008 to demonstrate its safety and efficacy in an animal model. After a clinical trial evaluating its safety and mapping capabilities in humans was completed in 2010, the Amigo™ RCS (Catheter Precision, Inc., Mount Olive, NJ, USA) underwent several scientific studies to examine its ability to assist in the mapping and ablation of various arrhythmias in comparison with the conventional manual approach. The Amigo™ RCS (Catheter Precision, Inc., Mount Olive, NJ, USA) achieved mapping and ablation success rates that were similar to those achieved with manual catheter manipulation, and no complications due to its use were observed. It was approved by the FDA for use in diagnostic EP studies of the right atrium and ventricle in 2012, with this indication later expanded in 2014 to include radiofrequency ablations. The device is currently compatible with the Blazer™ (Boston Scientific, Natick, MA, USA) and EZ STEER™ (Biosense Webster, Inc., Diamond Bar, CA, USA) catheter handles. Here, we present a clinical report in which the Amigo™ RCS (Catheter Precision, Inc., Mount Olive, NJ, USA) was employed to map and ablate symptomatic supraventricular tachycardia. Dr. Cohen’s clinical experience with this robotic system is also reviewed.

Radiofrequency catheter ablation of atrioventricular node reentrant tachycardia in children with limited fluoroscopy

BACKGROUND

Limited fluoroscopy cryo-ablation using a 3D electro-anatomical system (3DS) has been used for AVNRT in children. We aimed to facilitate a fluoroscopy limited approach of RF ablation of AVNRT in children.

METHODS

A retrospective study was performed of procedure parameters in children undergoing RF ablation of AVNRT in 75 consecutive children (June 2011 to November 2013 - Group A) using standard fluoroscopy techniques compared to those of 64 consecutive children (December 2013 to May 2015 - Group B), using a fluoroscopy limited approach with 3DS.

RESULTS

The acute success rate was 98.7% (74/75) and 98.4% (63/64) for groups A and B, respectively. The recurrence rate was 2.7% (2/74) and 0% (0/63) with a mean follow-up period of 45.5±12.1 and 14.3±6.1months for group A and group B, respectively. The mean procedure and fluoroscopy times were significantly lower for group B compared to group A (119±37 (43-203) and 0.83±1.04 (0.05-3.83) minutes versus 146±53 (72-250) and 16.1±8.9 (4.39-55) minutes, p<0.003 and p<0.0001, respectively). There were no ablation-related complications.

CONCLUSIONS

A fluoroscopy limited approach for RF ablation of AVNRT in children using a 3DS is easily acquired and adapted, and significantly reduces the fluoroscopy and procedure time with excellent efficacy, safety and low recurrence rate.

CONDENSED ABSTRACT

This study confirmed that a 3D mapping system (3DS) to guide ablations of AVNRT in children reduces radiation exposure. Combined, limited fluoroscopy and 3DS in a methodology that resembles the familiar conventional fluoroscopy approach for RF ablation of AVNRT in children is proposed. Combined limited fluoroscopy and RF-energy in children with AVNRT are associated with a shorter procedure time, minimal fluoroscopy time, a high success rate and a low recurrence rate.

Limited fluoroscopy catheter ablation of accessory pathways in children

BACKGROUND

Limited fluoroscopy ablation using 3D electro-anatomical system (3DS) has been used for arrhythmias in children, however it is not a common practice. We aimed to facilitate a fluoroscopy limited approach for ablation of accessory pathways (AP) in children.

METHODS

Following electrophysiologic (EP) catheter placement a single dual-plane fluoroscopic image (right anterior oblique-30° and left anterior oblique-60° views) was acquired and the 3DS views were rotated to be a perfect match to the fluoroscopy. Ninety-four consecutive pediatric patients [mean age 11.8±4.1 (4.2-18) years, 61.7% males] with Wolf-Parkinson-White syndrome underwent ablation of an AP. Fifty-seven had manifest AP, 54 had left-sided AP (LSAP) and 40 had right-sided AP (RSAP).

RESULTS

The acute success rate was 95.7% (90/94), with a recurrence rate of 1.1% (1/90) at a mean follow-up of 13±5.5 (4.4-22.9) months. Mean procedure and fluoroscopy times were 144±45 (55-262)min and 1.8±1.4 (0.1-5.6)min, respectively. Comparison of the first 20 procedures to the next 74 procedures demonstrated an extended procedure time (171±53min vs 135±38min, p<0.005), however the fluoroscopy time, the number of long applications, the time to effect, and the acute success rate were similar. There were no permanent ablation-related complications.

CONCLUSIONS

A limited fluoroscopy approach for ablation of AP in children using 3DS is easily acquired, adapted, reduces the fluoroscopy time, and has an excellent efficacy and safety profile.

Evaluation of Entrance Skin Dose during Catheter Ablation Procedures by Use of Reference Air-Kerma Displayed on Angiography Systems

BACKGROUND

Our aim in this study was to estimate entrance skin doses (ESDs) to patients who underwent catheter ablation procedures, by using a reference air-kerma (RAK) displayed on the monitor of an angiography system (displayed RAK).

METHODS

The displayed RAK was calibrated with use of an air-kerma value measured on a 20-cm-thick acrylic plate at the interventional reference point for the inclusion of backscattered x-rays (calibrated RAK). The ESD evaluated from the calibrated RAK (evaluated ESD) was verified through direct ESD measurements on an anthropomorphic phantom. The values of the evaluated ESD agreed with those of the measured ESD within a statistical error of 10% for both fluoroscopy and digital cine. The patient population included 356 consecutive patients (108 female and 248 male) who underwent catheter ablation procedures in the catheter laboratory of the Nagoya Daini Red-Cross Hospital from January 2013 to February 2014, where ablation procedures were performed for seven types of arrhythmias, i.e., atrial fibrillation (AF), atrial flutter (AFL), atrial tachycardia (AT), atrioventricular nodal reentrant tachycardia (AVNRT), ventricular premature contraction (VPC), ventricular tachycardia (VT), and Wolff-Parkinson-White syndrome (WPW).

RESULTS

Patients who had arrhythmias that received the highest evaluated ESD were those for AF, followed by those for VPC, AT, WPW, AFL, VT, and AVNRT.

CONCLUSIONS

Despite extremely long fluoroscopy times of up to 66.6 minutes in left anterior oblique projection, only one patient was considered to exceed a threshold dose of 2 Gy for the onset of radiation-induced skin injuries.

Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review

A thorough literature review about the current situation on the implementation of eye lens monitoring has been performed in order to provide recommendations regarding dosemeter types, calibration procedures and practical aspects of eye lens monitoring for interventional radiology personnel. Most relevant data and recommendations from about 100 papers have been analysed and classified in the following topics: challenges of today in eye lens monitoring; conversion coefficients, phantoms and calibration procedures for eye lens dose evaluation; correction factors and dosemeters for eye lens dose measurements; dosemeter position and influence of protective devices. The major findings of the review can be summarised as follows: the recommended operational quantity for the eye lens monitoring is H p (3). At present, several dosemeters are available for eye lens monitoring and calibration procedures are being developed. However, in practice, very often, alternative methods are used to assess the dose to the eye lens. A summary of correction factors found in the literature for the assessment of the eye lens dose is provided. These factors can give an estimation of the eye lens dose when alternative methods, such as the use of a whole body dosemeter, are used. A wide range of values is found, thus indicating the large uncertainty associated with these simplified methods. Reduction factors from most common protective devices obtained experimentally and using Monte Carlo calculations are presented. The paper concludes that the use of a dosemeter placed at collar level outside the lead apron can provide a useful first estimate of the eye lens exposure. However, for workplaces with estimated annual equivalent dose to the eye lens close to the dose limit, specific eye lens monitoring should be performed. Finally, training of the involved medical staff on the risks of ionising radiation for the eye lens and on the correct use of protective systems is strongly recommended.

Reduction of radiation exposure during atrial fibrillation ablation using a novel fluoroscopy image integrated 3-dimensional electroanatomic mapping system: A prospective, randomized, single-blind, and controlled study

OBJECTIVE

We explored whether the use of a novel fluoroscopy image integrated 3-dimensional electroanatomic mapping (F-EAM) system could result in a reduction of overall fluoroscopy time and radiation doses during the whole procedure of atrial fibrillation (AF) ablation.

METHODS

Eighty patients (44 men (55%); mean age 63 ± 10 years) who underwent catheter ablation due to paroxysmal AF were recruited consecutively in the present study. Patients were randomized (1:1) into 2 arms for AF ablation: one using a conventional 3-dimensional electroanatomical mapping (EAM) system and the other using the F-EAM system.

RESULTS

Fluoroscopy time (10:42 [interquartile range {IQR} 8:45-12:46] minutes:seconds vs 1:45 [IQR 1:05-2:22] minutes:seconds; P < .001) and radiation doses (2440 [IQR 1593-3091] cGy·cm(2) vs 652 [IQR 326-1489] cGy·cm(2); P < .001) in the EAM group were significantly greater than those in the F-EAM group. The majority of reduction of radiation exposure was achieved after transseptal puncture, which was near-zero fluoroscopic exposure. In total, approximately 84% of fluoroscopy time and 73% of radiation doses have been reduced during the AF ablation procedure using the F-EAM system compared to using the conventional EAM system. However, procedure time did not differ significantly (1:39 [IQR 1:18-2:10] hours:minutes vs 1:37 [IQR 1:17-1:50] hours:minutes; P = .362). During follow-up (5.9 ± 1.3 months), 61 patients (76.3%) had no recurrence of atrial arrhythmias. The recurrence rate between the 2 groups did not differ.

CONCLUSION

AF catheter ablation using the F-EAM system was safe and resulted in a significant reduction of radiation exposure to patients and staff without complicating the workflow of the procedure. A near-zero fluoroscopic catheter ablation procedure could be performed without compromising acute/mid-term efficacy and safety.

Minimal use of fluoroscopy to reduce fetal radiation exposure during radiofrequency catheter ablation of maternal supraventricular tachycardia

Electrophysiologic procedures in the young engender concern about the potential long-term effects of radiation exposure. This concern is manifold if such procedures are contemplated during pregnancy. Catheter ablations in pregnancy are indicated only in the presence of an unstable tachycardia that cannot be controlled by antiarrhythmic agents. This report describes the case of an 18-year-old pregnant woman and our stratagem to minimize irradiation of the mother and the fetus.

Contrast-Enhanced C-arm Computed Tomography Imaging of Myocardial Infarction in the Interventional Suite

OBJECTIVES

Cardiac C-arm computed tomography (CT) uses a standard C-arm fluoroscopy system rotating around the patient to provide CT-like images during interventional procedures without moving the patient to a conventional CT scanner. We hypothesized that C-arm CT can be used to visualize and quantify the size of perfusion defects and late enhancement resulting from a myocardial infarction (MI) using contrast-enhanced techniques similar to previous CT and magnetic resonance imaging studies.

MATERIALS AND METHODS

A balloon occlusion followed by reperfusion in a coronary artery was used to study acute and subacute MI in 12 swine. Electrocardiographically gated C-arm CT images were acquired the day of infarct creation (n = 6) or 4 weeks after infarct creation (n = 6). The images were acquired immediately after contrast injection, then at 1 minute, and every 5 minutes up to 30 minutes with no additional contrast. The volume of the infarct as measured on C-arm CT was compared against pathology.

RESULTS

The volume of acute MI, visualized as a combined region of hyperenhancement with a hypoenhanced core, correlated well with pathologic staining (concordance correlation, 0.89; P < 0.0001; mean [SD] difference, 0.67 [2.98]cm3). The volume of subacute MI, visualized as a region of hyperenhancement, correlated well with pathologic staining at imaging times 5 to 15 minutes after contrast injection (concordance correlation, 0.82; P < 0.001; mean difference, -0.64 [1.94]cm3).

CONCLUSIONS

C-arm CT visualization of acute and subacute MI is possible in a porcine model, but improvement in the imaging technique is important before clinical use. Visualization of MI in the catheterization laboratory may be possible and could provide 3-dimensional images for guidance during interventional procedures.

The Growing Culture Of A Minimally Fluoroscopic Approach In Electrophysiology Lab

Most of interventional procedures in cardiology are carried out under fluoroscopic imaging guidance. Besides other peri-interventional risks, radiation exposure should be considered for its stochastic (inducing malignancy) and deterministic effects on health (tissue reactions like erythema, hair loss and cataracts). In this article we analized the radiation risk from cardiovascular imaging to both patients and medical staff and discusses how customize the X-ray system and how to implement shielding measures in the cath lab. Finally, we reviewed the most recent developments and the latest findings in catheter navigation and 3D electronatomical mapping systems that may help to reduce patient and operator exposure.

Prospective European survey on atrial fibrillation ablation: clinical characteristics of patients and ablation strategies used in different countries

BACKGROUND

Atrial fibrillation (AF) ablation is widely adopted. Our aim was to conduct a prospective multicenter survey to verify patients' characteristics, approaches, and technologies adopted across Europe.

METHODS AND RESULTS

A total of 35 centers in 12 countries actively participated in the study and 940 patients (median age 60 years) were enrolled. AF was paroxysmal, persistent, and long-lasting persistent in 52.4%, 36%, and 11.6% of patients, respectively; 95.5% of patients were symptomatic and 91.4% were refractory to antiarrhythmic therapy. Redo procedures were performed in 20.9%. Pulmonary vein isolation (PVI) emerged as the cornerstone of ablative therapy and has been performed in 98.7% of procedures, with confirmation of PVI in 92.9% of cases. The ablation of nonparoxysmal AF was not generally limited to isolating the PVs and several adjunctive approaches are adopted, particularly in the case of long-lasting persistent AF. Linear lesions or elimination of complex fractionated atrial electrograms were more frequently added. Circular mapping catheters and imaging techniques were seen to be used in about two-thirds of cases. Radiofrequency energy was delivered through open irrigated catheters in 68% of cases.

CONCLUSIONS

European centers are largely following the recommendations of the guidelines and the expert consensus documents for AF ablation. AF ablation is mainly performed in relatively young patients with symptomatic drug refractory AF and no or minimal heart disease. Patients with paroxysmal AF are the most frequently treated with a quite uniform ablative approach across Europe. A less standardized approach was observed in nonparoxysmal AF patients.

Impact of respiration gating on image integration guided atrial fibrillation ablation

BACKGROUND

Radiofrequency (RF) catheter ablation guided by electroanatomic mapping systems is an effective therapy for atrial fibrillation. However, it may be affected by respiration movements. The aim of this study was to determine the impact of respiratory gating on procedural parameters in patients undergoing catheter ablation of atrial fibrillation (AF).

METHODS AND RESULTS

One-hundred forty consecutive patients undergoing pulmonary vein isolation were admitted to study. Respiratory gating module (AccuResp algorithm, Carto3, Biosense Webster) was enabled in 70 patients and disabled in 70 patients during procedures. Successful pulmonary vein isolation and sinus rhythm were obtained in all patients. A significant reduction in total procedure times [median 77, interquartile range (IQR 66-95) min vs median 82 (IQR 72-104) min, p < 0.05] and fluoroscopy times [median 14 (IQR 9-17) min vs median 16 (IQR 12-22) min, p < 0.05] were observed in the respiratory gated group. Although ablation times (duration between the first and last ablation) were significantly shorter in respiratory gated group [median 37 (IQR 32-53) min vs median 48 (IQR 39-65) min, p < 0.05], total RF application durations were not different between two groups [median 1,554 (IQR 1,213-2,196) s vs median 1,802 (IQR 1,344-2,448) s, p = 0.11]. Difference in electroanatomical map reconstruction times was not significant [median 14 (IQR 12-16) min in gated group vs median 13 (IQR 10-18) min in nongated group, p = 0.19].

CONCLUSION

Respiratory gating significantly improves fluoroscopy and ablation times during electroanatomic mapping guided AF ablation. Respiratory gated maps may provide uninterrupted continuous ablation applications. Furthermore, using automatic respiratory gating module does not prolong mapping times.

Practical ways to reduce radiation dose for patients and staff during device implantations and electrophysiological procedures

Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field.

Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures

Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of the present study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection in fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff were compared to radiation doses collected when the radiation dose rates were displayed. When the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose (Hp(10)) per procedure decreased from 68 to 28 μSv (p = 0.003) for this cardiologist and from 4.3 to 2.5 μSv (p = 0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection.

Assessment of eye and body dose for interventional radiologists, cardiologists, and other interventional staff

A dose limit for the eye of 20 mSv, as proposed by the ICRP, could be exceeded by interventional clinicians. Data on eye dose levels for interventional radiologists and cardiologists provided by medical physicists from hospitals around the UK have been collated. The results indicate that most hospitals would require one or more interventional clinicians to be classified and several would have exceeded a 20 mSv limit. Dose data in the literature have been reviewed to derive factors that might be used to predict eye dose levels based on dose per procedure or kerma-area product workload. These could be used in prior risk assessments to establish monitoring practice. An alternative approach to personnel dose monitoring in radiology applications using a collar dosimeter worn outside the lead apron as the first dosimeter is proposed. The collar dosimeter would provide an assessment of eye dose in terms of Hp(3) and body dose in terms of Hp(10), which could be divided by ten to provide an assessment of effective dose. If Hp(3) exceeded 1 mSv per month, regular monitoring with a head dosimeter would be recommended, and if Hp(10) exceeded 2 mSv per month, then an under-apron dosimeter should also be worn.

Single center experience of fluoroless AVNRT ablation guided by electroanatomic reconstruction in children and adolescents

BACKGROUND

Anatomical considerations and risks related to x-ray exposure make atrioventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety, and efficacy of performing fluoroless slow-pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents.

METHODS

Twenty-one consecutive patients (mean age 13.5 ± 2.4 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow-pathway potential and performed using a 4-mm-tip catheter.

RESULTS

Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 95%. Acute success was achieved in 100% of the patients with a median of two cryo-applications. Fluoroless ablation was feasible in 19 patients, while in two subjects 50 seconds and 45 seconds of x-ray were needed due to difficult progression of the catheters along the venous system. After a mean follow-up of 25 months, AVNRT recurred in five patients. All the recurrences were successfully treated with a second procedure. In three patients, a fluoroless cryoablation with a 6-mm-tip catheter was successfully performed, while in the remaining two patients, a single pulse of 60 seconds of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred.

CONCLUSIONS

Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow-pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow-pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

Reference levels and patient doses in interventional cardiology procedures in Greece

OBJECTIVES

To present a national survey that was performed for the establishment of national reference levels (RLs) for interventional cardiology (IC) procedures and to estimate the effective dose (E) received by the patient during these procedures.

METHODS

Data concerning the fluoroscopy time and air kerma-area product (P KA) during coronary angiography (CA), percutaneous coronary intervention (PCI), pacemaker implantation (PMI) and radiofrequency cardiac ablation (RFCA) from 26 centres were collected. Moreover, measurements concerning the performance of X-ray systems used in IC were performed in order to set system-related reference levels. P KA to E conversion factors were also calculated.

RESULTS

The suggested P KA RLs for CA, PCI, PMI and RFCA are 53 Gycm(2), 129 Gycm(2), 36 Gycm(2) and 146 Gycm(2), respectively, and the estimated E to the patient from these procedures is 9.7 mSv, 26.8 mSv, 5.5 mSv and 20.4 mSv, respectively. Reference levels for the fluoroscopic dose rate and dose per frame during image acquisition at the entrance of a water phantom are 29 mGy/min and 0.23 mGy/frame, respectively.

CONCLUSIONS

The suggested RLs are comparable to those suggested by other studies. Additional information concerning the complexity of the procedures and patient pathology should be collected for future reevaluation of the suggested RLs.

KEY POINTS

• The radiation dose imparted during fluoroscopically guided interventional procedures can be high • Understanding of reference levels might help optimise interventional cardiological procedures • Optimisation by changing the systems' settings seems feasible in some cases • Procedure complexity and the patient's clinical problem should be taken into account.

Recommendations for occupational radiation protection in interventional cardiology

The radiation dose received by cardiologists during percutaneous coronary interventions, electrophysiology procedures and other interventional cardiology procedures can vary by more than an order of magnitude for the same type of procedure and for similar patient doses. There is particular concern regarding occupational dose to the lens of the eye. This document provides recommendations for occupational radiation protection for physicians and other staff in the interventional suite. Simple methods for reducing or minimizing occupational radiation dose include: minimizing fluoroscopy time and the number of acquired images; using available patient dose reduction technologies; using good imaging-chain geometry; collimating; avoiding high-scatter areas; using protective shielding; using imaging equipment whose performance is controlled through a quality assurance programme; and wearing personal dosimeters so that you know your dose. Effective use of these methods requires both appropriate education and training in radiation protection for all interventional cardiology personnel, and the availability of appropriate protective tools and equipment. Regular review and investigation of personnel monitoring results, accompanied as appropriate by changes in how procedures are performed and equipment used, will ensure continual improvement in the practice of radiation protection in the interventional suite. These recommendations for occupational radiation protection in interventional cardiology and electrophysiology have been endorsed by the Asian Pacific Society of Interventional Cardiology, the European Association of Percutaneous Cardiovascular Interventions, the Latin American Society of Interventional Cardiology, and the Society for Cardiovascular Angiography and Interventions.

Radiation exposure of the operator during cardiac catheter ablation procedures

Radiation exposure of the operator during cardiac catheter ablation procedures was assessed for an experienced cardiologist adopting various measures of radiation protection and utilised electroanatomic navigation. Chip thermoluminescent dosemeters were placed at the eyes, chest, wrists and legs of the operator. The ranges of fluoroscopy time and air kerma area product values associated with cardiac ablation procedures were wide (6.3-48.3 min and 1.7-80.3 Gy cm(2), respectively). The measured median radiation doses per procedure for each monitored position were 23.6 and 21.3 μSv to the left and right wrists, respectively, 25.3 and 30.4 μSv to the left and right legs, respectively. The doses to the eyes were below the minimum detectable dose of 9 μSv. The estimated median effective dose was 22.5 μSv. Considering the actual workload of the operator, the calculated annual doses to the hands, legs and eyes, as well as the annual effective dose, were all below the corresponding limits. The findings of this study indicate that cardiac ablation procedures performed at a modern laboratory do not impose a high radiation hazard to the operator when radiation protection measures are routinely adopted.

Survey of the interventional cardiology procedures in Italy

Interventional cardiology procedures are increasing because they offer many advantages to patients compared with other techniques: therefore the Italian National Institution for Insurance against Accidents at Work decided to start a survey for monitoring the state-of-the-art regarding the professionals involved in those procedures. The survey covered six cardiology and medical physics Italian departments. Each centre was asked to record 10 examinations for five types of procedures: coronary angiography (CA), electrophysiology studies (ES), pacemaker implantation (PI), percutaneous transluminal coronary angioplasty (PTCA) and radiofrequency catheter ablation (RA). For each examination all the centres were requested to fill in a questionnaire containing information regarding the operator performing the examination, the patient and the procedure. A total of 290 examinations were recorded: 103 CA, 14 ES, 68 PI, 79 PTCA and 26 RA. As occupational doses are strongly related to patient doses, both patients and operators radiation dose data are reported. Ratios of maximum to minimum mean patient doses across the hospitals surveyed were 2.0, 3.9, 7.0, 1.8 and 1.4 for CA, ES, PI, PTCA and RA, respectively. The calculated rounded mean dose-area product values across all participating hospitals were comparable with other values reported in the literature. In general, specific radiation protection tools were used by all operators performing different procedures in all hospitals. A major issue in this survey was the absence of information about correlation between staff and patient doses in a single procedure: future studies could be more aimed to prospective goals where occupational exposures per procedure are monitored specifically.

Pulmonary venous anatomy imaging with low-dose, prospectively ECG-triggered, high-pitch 128-slice dual-source computed tomography

BACKGROUND

The efforts to reduce radiation from cardiac computed tomography (CT) are essential. Using a prospectively triggered, high-pitch dual-source CT protocol, we aim to determine the radiation dose and image quality in patients undergoing pulmonary vein (PV) imaging.

METHODS AND RESULTS

In 94 patients (61±9 years; 71% male) who underwent 128-slice dual-source CT (pitch 3.4), radiation dose and image quality were assessed and compared between 69 patients with sinus rhythm and 25 patients with atrial fibrillation. Radiation dose was compared in a subset of 19 patients with prior retrospective or prospectively triggered CT PV scans without high pitch. In a subset of 18 patients with prior magnetic resonance imaging for PV assessment, PV anatomy and scan duration were compared with high-pitch CT. Using the high-pitch protocol, total effective radiation dose was 1.4 (1.3, 1.9) mSv, with no difference between sinus rhythm and atrial fibrillation (1.4 versus 1.5 mSv; P=0.22). No high-pitch CT scans were nondiagnostic or had poor image quality. Radiation dose was reduced with high-pitch (1.6 mSv) compared with standard protocols (19.3 mSv; P<0.0001). This radiation dose reduction was seen with sinus rhythm (1.5 versus 16.7 mSv; P<0.0001) but was more profound with atrial fibrillation (1.9 versus 27.7 mSv; P=0.039). There was excellent agreement of PV anatomy (κ 0.84; P<0.0001) and a shorter CT scan duration (6 minutes) compared with magnetic resonance imaging (41 minutes; P<0.0001).

CONCLUSIONS

Using a high-pitch dual-source CT protocol, PV imaging can be performed with minimal radiation dose, short scan acquisition, and excellent image quality in patients with sinus rhythm or atrial fibrillation. This protocol highlights the success of new cardiac CT technology to minimize radiation exposure, giving clinicians a new low-dose imaging alternative to assess PV anatomy.

Contrast-enhanced C-arm CT evaluation of radiofrequency ablation lesions in the left ventricle

OBJECTIVES

The purpose of this study was to evaluate use of cardiac C-arm computed tomography (CT) in the assessment of the dimensions and temporal characteristics of radiofrequency ablation (RFA) lesions. This imaging modality uses a standard C-arm fluoroscopy system rotating around the patient, providing CT-like images during the RFA procedure.

BACKGROUND

Both cardiac magnetic resonance (CMR) and CT can be used to assess myocardial necrotic tissue. Several studies have reported visualizing cardiac RFA lesions with CMR; however, obtaining CMR images during interventional procedures is not common practice. Direct visualization of RFA lesions using C-arm CT during the procedure may improve outcomes and circumvent complications associated with cardiac ablation procedures.

METHODS

RFA lesions were created on the endocardial surface of the left ventricle of 9 swine using a 7-F RFA catheter. An electrocardiographically gated C-arm CT imaging protocol was used to acquire projection images during iodine contrast injection and after the injection every 5 min for up to 30 min, with no additional contrast. Reconstructed images were analyzed offline. The mean and SD of the signal intensity of the lesion and normal myocardium were measured in all images in each time series. Lesion dimensions and area were measured and compared in pathologic specimens and C-arm CT images.

RESULTS

All ablation lesions (n = 29) were visualized and lesion dimensions, as measured on C-arm CT, correlated well with postmortem tissue measurements (linear dimensions: concordance correlation = 0.87; area: concordance correlation = 0.90. Lesions were visualized as a perfusion defect on first-pass C-arm CT images with a signal intensity of 95 HU lower than that of normal myocardium (95% confidence interval: -111 HU to -79 HU). Images acquired at 1 and 5 min exhibited an enhancing ring surrounding the perfusion defect in 24 lesions (83%).

CONCLUSIONS

RFA lesion size, including transmurality, can be assessed using electrocardiographically gated cardiac C-arm CT in the interventional suite. Visualization of RFA lesions using cardiac C-arm CT may facilitate the assessment of adequate lesion delivery and provide valuable feedback during cardiac ablation procedures.

Application study of medical robots in vascular intervention

BACKGROUND

Based on the background of minimally invasive surgery and applications of medical robots, a vascular interventional robotic system has been developed that can be used in the field of vascular intervention.

METHODS

The robotic system comprises a propulsion system, an image navigation system and a virtual surgery training system. Integration of the three systems constitutes a vascular intervention prototype robotic system used to carry out in vitro vascular intervention and animal experiments.

RESULTS

On a transparent glass vascular model, a catheter was shown to enter an arbitrary branch of the vascular model with catheter motion meeting the requirements of clinical vascular intervention surgery (VIS); i.e. error band of catheter motion < 0.5 mm. In the animal experiments, 1.33-2.00 mm (4F-6F) diameter catheters were selectively inserted successfully into predefined targets in the animal, such as the renal, cardiovascular and cerebrovascular artery. Compared with conventional manual surgery, the time for robotic surgery is a little longer. There were no operative complications in the animal experiments.

CONCLUSIONS

These simulation and animal study results demonstrate that this vascular interventional robotic system allows doctors to perform angiography remotely and prevents them from radiation exposure. The system may be the basis for further clinical applications of vascular intervention.

Personal dosimetry for interventional operators: when and how should monitoring be done?

OBJECTIVE

Assessment of the potential doses to the hands and eyes for interventional radiologists and cardiologists can be difficult. A review of studies of doses to interventional operators reported in the literature has been undertaken.

METHODS

Distributions for staff dose to relevant parts of the body per unit dose-area product and for doses per procedure in cardiology have been analysed and mean, median and quartile values derived. The possibility of using these data to provide guidance for estimation of likely dose levels is considered.

RESULTS

Dose indicator values that could be used to predict orders of magnitude of doses to the eye, thyroid and hands from interventional operator workloads have been derived, based on the third quartile values, from the distributions of dose results analysed.

CONCLUSION

Dose estimates made in this way could be employed in risk assessments when reviewing protection and monitoring requirements. Data on the protection provided by different shielding and technique factors have also been reviewed to provide information for risk assessments. Recommendations on the positions in which dosemeters are worn should also be included in risk assessments, as dose measurements from suboptimal dosemeter use can be misleading.

Visualization of multiple catheters with electroanatomical mapping reduces X-ray exposure during atrial fibrillation ablation

AIMS

Atrial fibrillation (AF) ablation still requires long procedural time and high radiation exposure with its related risk for the patient and the operators. This study was designed to compare three different approaches of AF ablation to verify the hypothesis that image integration with electroanatomic mapping allows minimal use of fluoroscopy. Therefore, we evaluated the procedure and fluoroscopy times of ablation using three imaging modalities: conventional fluoroscopy, image integration electroanatomic mapping, and a new electroanatomic mapping system that provides visualization of multiple catheters.

METHODS AND RESULTS

One hundred and twenty patients with symptomatic refractory AF were enrolled in the study. Patients were randomly assigned to fluoroscopy alone (Group A, 40 patients), electroanatomic integration (Cartomerge®, Group B, 40 patients), and electroanatomic integration plus catheters visualization (Carto® 3 System, Group C, 40 patients) guided procedures. The ablation procedure aimed at isolating the pulmonary veins and creating lesion lines at the left atrial roof and left isthmus. Procedure and fluoroscopy parameters were recorded in all patients. Total procedure time and skin to catheter positioning time did not significantly differ between the groups. Total fluoroscopy time was statistically different between all three groups (Group A, 18'09″±5'00″; Group B, 9'48″±3'41″; Group C, 2'28″±1'40″; P<0.001). A significant difference was noted in ablation fluoroscopy time between all groups (P<0.001), mainly due to shortened fluoroscopy time in Group B (7'34″±3'15″) and Group C (0'21″±0'31″) when compared with Group A (16'07″±5'04″).

CONCLUSION

Image integration and, to a larger extent, visualization of multiple catheters allowed a minimal use of fluoroscopy in transcatheter AF ablation.

Nonfluoroscopic imaging systems reduce radiation exposure in children undergoing ablation of supraventricular tachycardia

BACKGROUND

The current standard of care for imaging during supraventricular tachycardia (SVT) ablation uses fluoroscopy, which exposes otherwise healthy children to the potential harmful effects of radiation.

OBJECTIVE

The purpose of this study was to determine whether the adjunct use of nonfluoroscopic imaging reduces radiation exposure during SVT ablation among children.

METHODS

This was a prospective, controlled, single-center study of patients age ≥8 years, weight ≥25 kg, with SVT and normal cardiac anatomy. Patients were randomized to control (fluoroscopy only) or study group (fluoroscopy + AcuNav intracardiac ultrasound + NavX electroanatomic mapping), stratified by operator to one of five electrophysiologists. Fluoroscopy times (minutes) and radiation doses (mGy) were recorded, and outcomes and adverse events were noted.

RESULTS

Seventy-four patients were enrolled (37 control, 37 study). Median age was 14.7 years (range 8.6-22.3 years); 61% had accessory pathways and 39% had atrioventricular nodal reentrant tachycardia. Nonfluoroscopic imaging reduced median fluoroscopy time by 59% (18.3 minutes vs 7.5 minutes, P <.001) and radiation exposure by 72% (387 vs 110 mGy, P <.001). In the study group, 26 of 37 had ≤10 minutes of fluoroscopy, including 2 with no fluoroscopy exposure and 2 with <30 seconds. Electrophysiologic procedure time was not affected by use of nonfluoroscopic imaging, but total case times were prolonged by 31 minutes (P <.001). Acute success was 97% in control and 100% in study patients, with no difference in adverse events.

CONCLUSION

Use of nonfluoroscopic imaging during SVT ablation in children resulted in substantial and immediate reductions in fluoroscopy time and radiation exposure without change in acute success or adverse event rates but did increase overall procedural time.

Comparison of non-gated vs. electrocardiogram-gated 64-detector-row computed tomography for integrated electroanatomic mapping in patients undergoing pulmonary vein isolation

AIMS

To compare non-gated vs. electrocardiogram (ECG)-gated 64-detector-row computed tomography (MDCT) of the left atrium (LA) for integrated electroanatomic mapping (EAM) in patients with paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

Twenty-nine consecutive patients with paroxysmal AF underwent MDCT prior to pulmonary vein isolation (PVI). All patients were in sinus rhythm both during CT imaging and PVI. Multi-detector-row computed tomography was performed in 15 patients without ECG-gating (non-gated MDCT) and in 14 patients with retrospective ECG-gating (ECG-gated MDCT). Image quality of LA reconstructions from MDCT was rated on a five-point scale (from 1 = excellent to 5 = segmentation failed). Registration error between LA geometry obtained from EAM and MDCT was calculated as the mean distance between EAM points and MDCT surface. In all patients, LA was successfully segmented from MDCT data. The segmentation process took 2:31 +/- 0:54 min for non-gated MDCT and 2:36 +/- 0:47 min for ECG-gated MDCT (P = 0.8). Image quality scores of LA reconstructions from non-gated and ECG-gated MDCT were 1.3 +/- 0.6 and 1.4 +/- 0.7, respectively (P = 0.76). There was no significant difference in the registration error between non-gated and ECG-gated MDCT (1.8 +/- 0.2 vs. 1.9 +/- 0.3 mm, respectively; P = 0.6). The radiation dose of non-gated MDCT was significantly lower compared with ECG-gated MDCT (4.6 +/- 1.4 vs. 13.4 +/- 3.6 mSv, respectively; P < 0.001).

CONCLUSION

Non-gated MDCT depicts LA with appropriate image quality for integrated EAM, while exposing patients to substantially lower radiation dose compared with ECG-gated MDCT.

Ablation of atrial fibrillation utilizing robotic catheter navigation in comparison to manual navigation and ablation: single-center experience

BACKGROUND

Robotic catheter navigation and ablation either with magnetic catheter driving or with electromechanical guidance have emerged in the recent years for the treatment of atrial fibrillation.

OBJECTIVE

The aim of this study was to compare our center's experience of atrial fibrillation ablation using the Hansen Robotic Medical System with our current manual ablation technique in terms of acute and chronic success, as well as procedure time and radiation exposure to both the patient and the operator.

METHODS

A total of 390 consecutive patients with symptomatic and drug-resistant atrial fibrillation (289 males, 62 +/- 11 years) were prospectively enrolled in the study. All patients underwent the procedure either with conventional manual ablation (group 1, n = 197) or with the robotic navigation system (RNS) (group 2, n = 193).

RESULTS

The success rate for RNS was 85% (164 patients), while for manual ablation it was 81% (159 patients) (p = 0.264) at 14.1 +/- 1.3 months with AADs previously ineffective. Fluoroscopy time was significantly lower for RNS (48.9 +/- 24.6 minutes for RNS vs. 58.4 +/- 20.1 minutes for manual ablation, P < 0.001). Mean fluoroscopy time was statistically reduced after 50 procedures (61.8 +/- 23.2 minutes for first 50 cases vs. 44.5 +/- 23.6 minutes for subsequent procedures, P < 0.0001).

CONCLUSION

Robotic navigation and ablation of atrial fibrillation is safe and effective. Fluoroscopy time decreases with experience.