Impact of nonfluoroscopic MediGuide™ tracking system on radiation exposure in radiofrequency ablation procedures (LESS-RADS registry)—an initial experience

Ultra-low radiation dose during electrophysiology procedures using optimized new generation fluoroscopy technology

BACKGROUND

Electrophysiology procedures require fluoroscopic guidance, with the associated potentially adverse effects of ionizing radiation. Newer fluoroscopy systems have more features that enable dose-reduction strategies. This study aimed to investigate any reduction in radiation dose between an older fluoroscopy system (Philips Integris H5000, Philips Healthcare, Einhoven, Netherlands) and one of the latest systems (Siemens Artis Q, Siemens Healthcare, Erlangen, Germany), optimized with dose-reduction strategies.

METHODS

Radiation dose measures were collected over a 2-year period in a single electrophysiology laboratory. Procedures were separated into seven groups: devices, biventricular devices, electrophysiology studies, standard radiofrequency ablation, complex atrial ablation, ablation for ventricular arrhythmias, and pulmonary vein isolation. In the first year, an older fluoroscopy system was used, and in the second year, a new system, with dose reduction strategies. Comparisons were also made to the literature with regard to radiation dose levels.

RESULTS

Patient characteristics, fluoroscopy times, number of digital acquisitions, procedural times, and procedural success were largely similar between the old and new system across procedure groups. Overall dose area product (DAP) was reduced by 91% (5.0 [2.0-17.0] to 0.45 [0.16-2.61] Gycm² [P > 0.001]) with the new system and was lower across all groups. DAP readings with the new system are some of the lowest published in the literature in all groups.

CONCLUSION

An optimized contemporary digital fluoroscopy system, with low radiation dose configuration and continued good procedural practice, can result in ultra-low radiation levels for all electrophysiology procedures, without compromising procedural time or procedural success.

Ablation of idiopathic ventricular arrhythmia using zero-fluoroscopy approach with equivalent efficacy and less fatigue: A multicenter comparative study

The efficacy of a completely zero-fluoroscopy (ZF) approach for the catheter ablation of idiopathic ventricular arrhythmias (VAs) and whether it has advantages over the conventional fluoroscopy (F) approach are still unknown. The aim of this study was to compare the safety and efficacy of a completely ZF approach with those of the conventional F approach in the ablation of idiopathic VAs.We conducted a prospective study involving 7 centers in China. Consecutive patients (n = 489, mean age 45.3 ± 15.3 years, 44.8% male) with idiopathic VAs were recruited. Eligible participants were assigned to either a ZF (n = 163) or F (n = 326) approach at a ratio of 1:2. The completely ZF approach was successful in 163 (100%) patients for electrophysiological study, and in 151 patients (94.4%) for arrhythmia ablation with 9 cases having to switch to the F approach due to the need for coronary angiography. There was no significant difference between the ZF approach and F approach in procedural success rate (84.1% vs 85.4%, respectively), arrhythmia recurrence (1.9% vs 2.2%), or severe complications (0.6% vs 0.9%). The medical staffs using the ZF approach did not wear heavy protective apparels, thus experienced significantly less fatigue compared with those using the F approach (2.1 ± 0.7 vs 3.9 ± 1.6, P < 0.05).The completely ZF approach is as safe and efficient as the conventional F approach for the electrophysiological study and the ablation of idiopathic VAs. The medical staffs using ZF approach felt less fatigue and received less exposure to radiation.

Radiation dose and mortality risk to children undergoing therapeutic interventional cardiology

BACKGROUND

Children undergoing interventional cardiology procedures deserve special concern due to the greater radiation sensitivity of their tissues and more remaining years of life during which a radiation-induced cancer may develop.

PURPOSE

To determine the patient radiation dose for pediatric therapeutic interventional cardiology and to estimate the patient effective dose and lifetime mortality risk to children associated with five common procedures.

MATERIAL AND METHODS

Ninety children with congenital heart defects undergoing interventional therapy were enrolled in this study. Data regarding fluoroscopy and radiography time, dose-area product (DAP) and peak skin dose (PSD) for each case were measured. Patients were divided into five groups. The patient effective dose (E) was calculated using a multiplicative model of ICRP 60. The overall lifetime mortality risk was evaluated using appropriate risk coefficients.

RESULTS

The mean, median, standard deviation, and range of time, PSD, DAP, and E were presented for the five study groups. When these metrics were considered, there were wide variations for different cases within the same group and statistically significant differences between the five groups. The PSD correlated significantly with DAP (Pearson r = 0.70; P < 0.01), but the correlation in individual cases was poor. For all cases, the range of E was found to be between 0.44 and 66.7 mSv. The corresponding risk of lifetime mortality was 1.16 per thousand.

CONCLUSION

The current study provides overall data on the time, PSD, E, and lifetime mortality risk for pediatric therapeutic interventional cardiology. Radio frequency ablation showed the highest radiation risk.

Non-fluoroscopic catheter tracking for fluoroscopy reduction in interventional electrophysiology

A technological platform (MediGuide) has been recently introduced for non-fluoroscopic catheter tracking. In several studies, we have demonstrated that the application of this non-fluoroscopic catheter visualization system (NFCV) reduces fluoroscopy time and dose by 90-95% in a variety of electrophysiology (EP) procedures. This can be of relevance not only to the patients, but also to the nurses and physicians working in the EP lab. Furthermore, in a subset of indications such as supraventricular tachycardias, NFCV enables a fully non-fluoroscopic procedure and allows the lab staff to work without wearing lead aprons. With this protocol, we demonstrate that even complex procedures such as ablations of atrial fibrillation, that are typically associated with fluoroscopy times of >30 min in conventional settings, can safely be performed with a reduction of >90% in fluoroscopy exposure by the additional use of NFCV.

Ablation of typical atrial flutter using a non-fluoroscopic catheter tracking system vs. conventional fluoroscopy--results from a prospective randomized study

AIMS

Reduction of radiation exposure using a sensor-based non-fluoroscopic catheter tracking (NFCT) system (MediGuide™, St Jude Medical, Inc.) was recently demonstrated by retrospective comparisons. We aimed to prospectively compare the effects of using NFCT vs. standard fluoroscopy on procedural parameters in patients undergoing radiofrequency ablation of typical atrial flutter.

METHODS AND RESULTS

We prospectively randomized 40 patients undergoing cavotricuspid isthmus ablation for typical atrial flutter to either NFCT (n = 20) or conventional fluoroscopy (CONV, n = 20). Procedural parameters such as fluoroscopy time, radiation dose, and procedure duration, as well as periprocedural complications were compared. There were no statistically significant differences in baseline characteristics between the two groups. Bidirectional isthmus block was achieved in all patients. Fluoroscopy time was significantly reduced in the NFCT group {0.3 [inter-quartile range (IQR) 0.2; 0.48] min} when compared with CONV [5.7 (IQR 4.2; 11.5) min] (P < 0.001). This resulted in a significant reduction in radiation dose in patients randomized to NFCT [17.4 (IQR 11; 206.6) cGy cm(2)] vs. the CONV group [418.4 (IQR 277; 812.2) cGy cm(2)] (P < 0.001). There were no significant differences in procedure duration between the NFCT group [49.5 (IQR 37; 65) min] when compared with the CONV group [33.5 (IQR 26.3; 55.5) min] (P = 0.053). No adverse events were recorded. Freedom from atrial flutter at 6 months of follow-up was 19/20 (95%) in the NFCT and 18/20 (90%) in the CONV group (n.s.).

CONCLUSION

In this first prospective randomized study, by comparing NFCT with standard fluoroscopy in patients undergoing radiofrequency ablation of typical atrial flutter, NFCT significantly reduced both radiation dose and fluoroscopy time with no effects on procedural duration. These findings support the incorporation of NFCT in routine clinical use.

MediGuide-impact on catheter ablation techniques and workflow

Since the introduction of percutaneous intervention in modern medical science, specifically cardiovascular medicine fluoroscopy has remained the gold standard for navigation inside the cardiac structures. As the complexity of the procedures continue to increase with advances in interventional electrophysiology, the procedural times and fluoroscopy times have proportionately increased and the risks of radiation exposure both to the patients as well as the operator continue to rise. 3D electroanatomic mapping systems have to some extent complemented fluoroscopic imaging in improving catheter navigation and forming a solid platform for exploring the electroanatomic details of the target substrate. The 3D mapping systems are still limited as they continue to be static representations of a dynamic heart without being completely integrated with fluoroscopy. The field needed a technological solution that could add a dynamic positioning system that can be successfully incorporated into fluoroscopic imaging as well as electroanatomic imaging modalities. MediGuide is one such innovative technology that exploits the geo-positioning system principles. It employs a transmitter mounted on the X-ray panel that emits an electromagnetic field within which sensor-equipped diagnostic and ablation catheters are tracked within prerecorded fluoroscopic images. MediGuide is also integrated with NavX mapping system and helps in developing better 3D images by field scaling-a process that reduces field distortions that occur from impedance mapping alone. In this review, we discuss about the principle of MediGuide technology, the catheter ablation techniques, and the workflow in the EP lab for different procedures.