Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance

BACKGROUND

Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined.

OBJECTIVES

The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR).

METHODS

A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes.

RESULTS

In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation.

CONCLUSIONS

Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.

A new implantable tool for repeated assessment of supraventricular electrophysiology and atrial fibrillation susceptibility in freely moving rats

The complex pathophysiology of atrial fibrillation (AF) is governed by multiple risk factors in ways that are still elusive. Basic electrophysiological properties, including atrial effective refractory period (AERP) and conduction velocity, are major factors determining the susceptibility of the atrial myocardium to AF. Although there is a great need for affordable animal models in this field of research, in vivo rodent studies are limited by technical challenges. Recently, we introduced an implantable system for long-term assessment of AF susceptibility in ambulatory rats. However, technical considerations did not allow us to perform concomitant supraventricular electrophysiology measurements. Here, we designed a novel quadripolar electrode specifically adapted for comprehensive atrial studies in ambulatory rats. Electrodes were fabricated from medical-grade silicone, four platinum-iridium poles, and stainless-steel fixating pins. Initial quality validation was performed ex vivo, followed by implantation in adult rats and repeated electrophysiological studies 1, 4, and 8 wk postimplantation. Capture threshold was stable. Baseline AERP values (38.1 ± 2.3 and 39.5 ± 2.0 using 70-ms and 120-ms S1-S1 cycle lengths, respectively) confirmed the expected absence of rate adaptation in the unanesthetized state and validated our prediction that markedly higher values reported under anesthesia are nonphysiological. Evaluation of AF substrate in parallel with electrophysiological parameters validated our recent finding of a gradual increase in AF susceptibility over time and demonstrated that this phenomenon is associated with an electrical remodeling process characterized by AERP shortening. Our findings indicate that the miniature quadripolar electrode is a potent new tool, which opens a window of opportunities for better utilization of rats in AF research.NEW & NOTEWORTHY Rodents are increasingly used in AF research. However, technical challenges restrict long-term supraventricular electrophysiology studies in these species. Here, we developed an implantable electrode adapted for such studies in the rat. Our findings indicate that this new tool is effective for long-term follow-up of critical parameters such as atrial refractoriness. Obtained data shed light on the normal electrophysiology and on the increased AF susceptibility that develops in rats with implanted atrial electrodes over time.

Heart-on-a-Chip Model with Integrated Extra- and Intracellular Bioelectronics for Monitoring Cardiac Electrophysiology under Acute Hypoxia

We demonstrated a bioelectronic heart-on-a-chip model for studying the effects of acute hypoxia on cardiac function. A microfluidic channel enabled rapid modulation of medium oxygenation, which mimicked the regimes induced by a temporary coronary occlusion and reversibly activated hypoxia-related transduction pathways in HL-1 cardiac model cells. Extracellular bioelectronics provided continuous readouts demonstrating that hypoxic cells experienced an initial period of tachycardia followed by a reduction in beat rate and eventually arrhythmia. Intracellular bioelectronics consisting of Pt nanopillars temporarily entered the cytosol following electroporation, yielding action potential (AP)-like readouts. We found that APs narrowed during hypoxia, consistent with proposed mechanisms by which oxygen deficits activate ATP-dependent K⁺ channels that promote membrane repolarization. Significantly, both extra- and intracellular devices could be multiplexed, enabling mapping capabilities unachievable by other electrophysiological tools. Our platform represents a significant advance toward understanding electrophysiological responses to hypoxia and could be applicable to disease modeling and drug development.

Feasibility of Using Adjunctive Optogenetic Technologies in Cardiomyocyte Phenotyping - from the Single Cell to the Whole Heart

In 1791, Galvani established that electricity activated excitable cells. In the two centuries that followed, electrode stimulation of neuronal, skeletal and cardiac muscle became the adjunctive method of choice in experimental, electrophysiological, and clinical arenas. This approach underpins breakthrough technologies like implantable cardiac pacemakers that we currently take for granted. However, the contact dependence, and field stimulation that electrical depolarization delivers brings inherent limitations to the scope and experimental scale that can be achieved. Many of these were not exposed until reliable in vitro stem-cell derived experimental materials, with genotypes of interest, were produced in the numbers needed for multi-well screening platforms (for toxicity or efficacy studies) or the 2D or 3D tissue surrogates required to study propagation of depolarization within multicellular constructs that mimic clinically relevant arrhythmia in the heart or brain. Here the limitations of classical electrode stimulation are discussed. We describe how these are overcome by optogenetic tools which put electrically excitable cells under the control of light. We discuss how this enables studies in cardiac material from the single cell to the whole heart scale. We review the current commercial platforms that incorporate optogenetic stimulation strategies, and summarize the global literature to date on cardiac applications of optogenetics. We show that the advantages of optogenetic stimulation relevant to iPS-CM based screening include independence from contact, elimination of electrical stimulation artefacts in field potential measuring approaches such as the multi-electrode array, and the ability to print re-entrant patterns of depolarization at will on 2D cardiomyocyte monolayers.

Cost-effective and multifunctional acquisition system for in vitro electrophysiological investigations with multi-electrode arrays

In vitro multi-electrode array (MEA) technology is nowadays involved in a wide range of applications beyond neuroscience, such as cardiac electrophysiology and bio-interface studies. However, the cost of commercially available acquisition systems severely limits its adoption outside specialized laboratories with high budget capabilities. Thus, the availability of low-cost methods to acquire signals from MEAs is important to allow research labs worldwide to exploit this technology for an ever-expanding pool of experiments independently from their economic possibilities. Here, we provide a comprehensive toolset to assemble a multifunctional in vitro MEA acquisition system with a total cost 80% lower than standard commercial solutions. We demonstrate the capabilities of this acquisition system by employing it to i) characterize commercial MEA devices by means of electrical impedance measurements ii) record activity from cultures of HL-1 cells extracellularly, and iii) electroporate HL-1 cells through nanostructured MEAs and record intracellular signals.

Nonthrombogenic, stretchable, active multielectrode array for electroanatomical mapping

High-precision monitoring of electrophysiological signals with high spatial and temporal resolutions is one of the most important subjects for elucidating physiology functions. Recently, ultraflexible multielectrode arrays (MEAs) have been fabricated to establish conformal contacts with the surface of organs and to measure propagation of electrophysiological signals with high spatial-temporal resolution; however, plastic substrates have high Young's modulus, causing difficulties in creating appropriate stretchability and blood compatibility for applying them on the dynamically moving and surgical bleeding surface of the heart. Here, we have successfully fabricated an active MEA that simultaneously achieves nonthrombogenicity, stretchability, and stability, which allows long-term electrocardiographic (ECG) monitoring of the dynamically moving hearts of rats even with capillary bleeding. Because of the active data readout, the measured ECG signals exhibit a high signal-to-noise ratio of 52 dB. The novel stretchable MEA is carefully designed using state-of-the-art engineering techniques by combining extraordinarily high gain organic electrochemical transistors processed on microgrid substrates and a coating of poly(3-methoxypropyl acrylate), which exhibits significant antithrombotic properties while maintaining excellent ionic conductivity.

[New generation implantable loop recorders can be safely managed by certified nurses]

. New generation implantable loop recorders can be safely managed by certified nurses.

INTRODUCTION

Implantable loop recorders (ILR) are recommended for several cardiac disorders: the recent miniaturization processes eased their implant and management.

AIM

To describe the advantages of the ILR implant, patients' education and remote control performed by expert certified nurses.

METHODS

Retrospective analysis of consecutive ILR implants of our centre, preformed between May and December 2016: the complications occurred in patients implanted by doctors and nurses were described. Nurses were certified after a two days course and 3 implants assisted by a medical doctor.

RESULTS

157 patients were implanted with a ICM Reveal LINQ (Medtronic): 74 (47%) by physicians electrophysiologists and 83 (53%) out of the electrophysiology room, by certified nurses. The two groups of patients were not fully comparable because more complex patients were implanted by the physician. All the loop recorders were easily implanted adverse without events during the procedure and after 30 days. Two minor bleedings occurred 24 hours after the implant: 1 in a patient implanted by a physician and the other by a nurse. Both were rapidly solved by finger pressure.

CONCLUSIONS

The ILR implants can be safely performed by trained nurses, out of the elettrophysiology room, with benefits for the patients and the hospital.

Total laser cycles-a measure of transvenous lead extraction difficulty

BACKGROUND

Several variables have been identified as predictors for difficult or complicated transvenous lead extraction (TLE), including age and number of implanted leads, as well as patient's age; however, a standard measure of TLE difficulty has not been described.

OBJECTIVE

Total laser cycles (TLCs) delivered during laser-assisted TLE is an objective variable that could reflect the difficulty of TLE. This study investigated whether TLC is correlated with known predictors of difficult TLE.

METHODS

In a retrospective study of TLE procedures using the laser sheath, we analyzed TLC delivered and compared it to established predictors of procedural failure and complications.

RESULTS

Of 166 patients undergoing TLE, the laser sheath (SLS II or Glidelight, Spectranetics Inc.,) was used as the primary extraction sheath in 130 patients, and 100 patients had complete TLC data available. The mean age of the oldest lead (AOL) was 7.1 ± 3.2 years with a median of 6.91 (interquartile range [IQR] 0.48-16.69) years, and 1.6 ± 0.7 leads (range, 1-4) were extracted per procedure. Two thirds of procedures involved ICD leads. Clinical success was 99%, with one patient (1%) experiencing a major complication. Median TLC delivered was 1165 (IQR, 567-2062; range, 49-9522). TLC was positively correlated with AOL (r = 0.227, p = 0.023), and the combined age of leads was extracted (r = 0.307, p = 0.002). TLC was also positively correlated with number of leads extracted per procedure (ρ = 0.227, p = 0.024). There was a non-significant negative trend towards correlation between TLC and patient's age (r = -0.112, p = 0.268).

CONCLUSION

TLC showed significant correlation with known predictors of difficulty during TLE using the laser sheath. TLC is an objective method to report the difficulty of TLE and could usefully be reported in future series of laser lead extractions.

An algorithm for rotor tracking in atrial fibrillation using graph search-based periodic peak detection

Rotors are rotating electrical waves that may sustain atrial fibrillation (AF); thereby providing therapeutic targets for catheter ablation. We propose a method for identifying rotors from circular catheter recordings of bipolar intracardiac electrograms (EGM) during AF. We use dominant frequency-based periodicity detection along with a graph search algorithm to identify the most dominant periodic activations or peaks of interest in each bipolar EGM recorded by a multipolar circular catheter. We then track the activations across catheter bipoles to determine whether they conform to the rotational pattern of a rotor. The performance of the proposed method is tested on simulated bipolar EGM arrays containing rotor activation corrupted by noise and complex aperiodic signal features. The method is shown to perform with high accuracy (up to 98% sensitivity and 100% specificity) in detecting simulated rotors and may serve to guide rotor ablation in patients with AF.

Investigating Regional Variation of Cardiac Implantable Electrical Device Implant Rates in European Healthcare Systems: What Drives Differences?

Despite established efficacy for cardiac implantable electrical devices (CIEDs), large differences in CIED implant rates have been documented across and within countries. The aim of this paper is to investigate the influence of socio-economic, epidemiological and supply side factors on CIED implant rates across 57 Regions in 5 EU countries and to assess the feasibility of using administrative data for this purpose. A total of 1 330 098 hospitalizations for CIED procedures extracted from hospital discharge databases in Austria, England, Germany, Italy and Slovenia from 2008 to 2012 was used in the analysis. Higher levels of tertiary education among the labour force and percent of aged population are positively associated with implant rates of CIED. Regional per capita GDP and number of implanting centres appear to have no significant effect. Institutional factors are shown to be important for the diffusion of CIED. Wide variation in CIED implant rates across and within five EU countries is undeniable. However, regional factors play a limited part in explaining these differences with few exceptions. Administrative databases are a valuable source of data for investigating the diffusion of medical technologies, while the choice of appropriate modelling strategy is crucial in identifying the drivers for variation across countries. © 2017 The Authors. Health Economics published by John Wiley & Sons, Ltd.

Computational Modeling of Open-Irrigated Electrodes for Radiofrequency Cardiac Ablation Including Blood Motion-Saline Flow Interaction

Radiofrequency catheter ablation (RFCA) is a routine treatment for cardiac arrhythmias. During RFCA, the electrode-tissue interface temperature should be kept below 80 °C to avoid thrombus formation. Open-irrigated electrodes facilitate power delivery while keeping low temperatures around the catheter. No computational model of an open-irrigated electrode in endocardial RFCA accounting for both the saline irrigation flow and the blood motion in the cardiac chamber has been proposed yet. We present the first computational model including both effects at once. The model has been validated against existing experimental results. Computational results showed that the surface lesion width and blood temperature are affected by both the electrode design and the irrigation flow rate. Smaller surface lesion widths and blood temperatures are obtained with higher irrigation flow rate, while the lesion depth is not affected by changing the irrigation flow rate. Larger lesions are obtained with increasing power and the electrode-tissue contact. Also, larger lesions are obtained when electrode is placed horizontally. Overall, the computational findings are in close agreement with previous experimental results providing an excellent tool for future catheter research.

Comparative analysis of diagnostic 12-lead electrocardiography and 3-dimensional noninvasive mapping

The clinical utility of noninvasive electrocardiographic imaging has been demonstrated in a variety of conditions. It has recently been shown to have superior predictive accuracy and higher clinical value than validated 12-lead electrogram algorithms in the localization of arrhythmias arising from the ventricular outflow tract, and displays similar potential in other conditions.

Which is the best catheter to perform atrial fibrillation ablation? A comparison between standard ThermoCool, SmartTouch, and Surround Flow catheters

INTRODUCTION

Catheter ablation (CA) is an established therapy for atrial fibrillation (AF). The SmartTouch catheter (STc) provides information about catheter tip to tissue contact force (CF). The Surround Flow catheter (SFc) provides a uniform cooling of the tip during ablation. We sought to analyze the impact of STc and SFc on CA of paroxysmal AF in terms of feasibility and acute efficacy.

METHODS AND RESULTS

Sixty-three patients (mean age 57.6 ± 9.8 years, 53 males) with paroxysmal AF underwent pulmonary veins (PVs) antral isolation, by using standard ThermoCool catheter (TCc) in 21, STc in 21, and SFc in 21. Total procedural, fluoroscopy, and radiofrequency (RF) delivery times; percentage of persistently deconnected PVs after 30 min; and percentage of isolated PVs at the end of the procedure were measured. The use of both STc and SFc obtained a reduction of fluoroscopy time (TCc 34 ± 18 min, STc 20 ± 10 min, p < 0.001; SFc 21 ± 13 min, p = 0.02 vs TCc) and RF time (TCc 41 ± 13 min, STc 30 ± 14 min, p = 0.013; SFc 30 ± 9 min, p < 0.01 vs TCc). The use of STc resulted in a reduction of procedural time (TCc 181 ± 53 min, STc 140 ± 53 min, p < 0.001; SFc 170 ± 51 min, p = NS vs TCc). The percentage of isolated PVs was comparable between groups (TCc 96 % vs STc 98 % vs SFc 96 %; p = NS). The percentage of deconnected PVs at 30 min was lower in TCc (89 %) than in STc (95 %) and in SFc (95 %) group (p < 0.05).

CONCLUSIONS

Both STc and SFc allowed a simplification of CA of paroxysmal AF. In addition, they reduced early PVs reconnection. Sixty-three patients with paroxysmal AF underwent ablation by standard ThermoCool, SmartTouch, or Surround Flow catheter. Both the SmartTouch and the Surround Flow significantly reduced radiofrequency and fluoroscopy times, as well as pulmonary veins reconnection rate at 30 min. Moreover, the SmartTouch reduced overall duration of the procedure.

[Electrocardiotherapy using pericardoscopy]

The standard transvenous electrocardiostimulation (ECS) is currently used in many specialized hospitals. The authors offered and launched systematic application of simple but available technique of epymiocardiac ECS using pericardoscopy since middle of 80th. According to this principle, the authors developed some diversities of manipulation which are distinctive due to their availability, reliability and supersafety. The method could be recommended for wide-spread usage in practice because of high efficacy, few complications and absence of fatal outcomes in correct intervention. Described methods used in treatment of considerable quantity of patients and adapted to real work conditions of public health hospitals.

Measurement of electrical coupling between cardiac ablation catheters and tissue

Managing cardiac arrhythmias with catheter ablation requires positioning electrodes in contact with myocardial tissue. Objective measures to assess contact and effective coupling of ablation energy are sought. An electrical coupling index (ECI) was devised using complex impedance at 20 kHz to perform in the presence of RF ablation and deliver information about electrical interactions between the tip electrode and its adjacent environment. ECI was derived and compared with clinical judgment, pacing threshold, electrogram amplitude, and ablation lesion depth and transmurality in a porcine model. ECI was also compared with force and displacement using ex vivo bovine myocardial muscle. Mean noncontact ECI was 97.2 ± 14.3 and increased to 145.2 ± 33.6 (p <; 0.001) in clinician assessed (CLIN) moderate contact. ECI significantly improved CLIN's prediction of the variance in pacing threshold from 48.7% to 56.8% ( ). ECI was indicative of contact force under conditions of smooth myocardium. Transmural lesions were associated with higher pre-RF (109 ± 17 versus 149 ± 25, ) and during-RF (82 ± 9 versus 101 ± 17, ) ECI levels. ECI is a tip specific, robust, correlate with contact and ablation efficacy, and can potentially add to clinical interpretation of electrical coupling during electrophysiology procedures.

A fully implantable pacemaker for the mouse: from battery to wireless power

Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice.

Anesthetic considerations for electrophysiologic procedures

The array of diagnostic and therapeutic procedures performed in the cardiology electrophysiology laboratory has expanded rapidly. Increasingly more facilities and cardiologists are performing these procedures, and the number of patients for whom these procedures are indicated is expanding. Because of the complexity of the procedures and associated patient comorbidity, anesthesia providers will become more involved in providing care in the electrophysiology laboratory. Therefore, anesthesia providers must be prepared to handle a broad range of case complexity. This article addresses the implications of providing anesthesia safely and effectively in the electrophysiology laboratory.

Automatic detection of multiple and overlapping EP catheters in fluoroscopic sequences

We propose a method to perform automatic detection of electrophysiology (EP) catheters in fluoroscopic sequences. Our approach does not need any initialization, is completely automatic, and can detect an arbitrary number of catheters at the same time. The method is based on the usage of blob detectors and clustering in order to detect all catheter electrodes, overlapping or not, within the X-ray images. The proposed technique is validated on 1422 fluoroscopic images yielding a tip detection rate of 99.3% and mean distance of 0.5mm from manually labeled ground truth centroids for all electrodes.

[The use of implantable devices for long-term monitoring of cardiac rhythm after surgical treatment of atrial fibrillation in patients with ischemic heart disease]

We present in this paper experience of the use of implantable devices for long-term monitoring of cardiac rhythm after one stage operation of coronary artery bypass grafting (CABG) and radiofrequency ablation of atrial fibrillation (AF) source and results of a prospective randomized study, in which we included patients (n=95) with persistent AF and ischemic heart disease. These patients were randomized into 3 groups: with radiofrequency isolation of ostia of pulmonary veins (group 1, n=31), radiofrequency modified mini-maze procedure (group 2, n=30); CABG without AF elimination (control group 3, n=34). Implantable devices Reveal XT were used in 53 patients (21, 25, and 7 in groups 1, 2, and 3, respectively). According to data obtained with these devices AF was absent in 86.7, 95.6, 53%, and in 80, 86.2, 44.1% of patients in groups 1, 2, 3 after 1 and 2 years after operation, respectively). In 24% of patients Reveal devices also registered asymptomati-c arrhythmias. The use of implantable devices for monitoring of rhythm allowed to detect such arrhythmia and to provide timely correction of therapy.

A novel technique for zero-fluoroscopy catheter ablation used to manage Wolff-Parkinson-White syndrome with a left-sided accessory pathway

Conventional catheter ablation of cardiac arrhythmias is associated with the potential adverse effects of low-dose ionizing radiation on both patients and laboratory personnel. Due to the greater radiation sensitivity and the longer life expectancy of children, reduction of radiation exposure for them is of particular importance. A novel technique for zero-fluoroscopy catheter ablation is described using real-time tissue-tip contact force measurements for a 10-year-old boy who had Wolff-Parkinson-White syndrome with a left-sided accessory pathway.

First in vivo use of a capacitive micromachined ultrasound transducer array-based imaging and ablation catheter

OBJECTIVES

The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures.

METHODS

The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed.

RESULTS

The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites.

CONCLUSIONS

Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures.

Materials for multifunctional balloon catheters with capabilities in cardiac electrophysiological mapping and ablation therapy

Developing advanced surgical tools for minimally invasive procedures represents an activity of central importance to improving human health. A key challenge is in establishing biocompatible interfaces between the classes of semiconductor device and sensor technologies that might be most useful in this context and the soft, curvilinear surfaces of the body. This paper describes a solution based on materials that integrate directly with the thin elastic membranes of otherwise conventional balloon catheters, to provide diverse, multimodal functionality suitable for clinical use. As examples, we present sensors for measuring temperature, flow, tactile, optical and electrophysiological data, together with radiofrequency electrodes for controlled, local ablation of tissue. Use of such 'instrumented' balloon catheters in live animal models illustrates their operation, as well as their specific utility in cardiac ablation therapy. The same concepts can be applied to other substrates of interest, such as surgical gloves.

[A method of real-time sampling and smooth scrolling in epicardial mapping system]

In order to control real-time sampling and achieve smooth scroll wave in the epicardial mapping system, which has 128 channels and a sampling rate of 2kHz/channel, we have designed a user interface using Direct-Draw in cooperation with multiple-thread technology and extracting method. This method has proven to be feasible in animal experiment.

The potential of dual camera systems for multimodal imaging of cardiac electrophysiology and metabolism

Fluorescence imaging has become a common modality in cardiac electrodynamics. A single fluorescent parameter is typically measured. Given the growing emphasis on simultaneous imaging of more than one cardiac variable, we present an analysis of the potential of dual camera imaging, using as an example our straightforward dual camera system that allows simultaneous measurement of two dynamic quantities from the same region of the heart. The advantages of our system over others include an optional software camera calibration routine that eliminates the need for precise camera alignment. The system allows for rapid setup, dichroic image separation, dual-rate imaging, and high spatial resolution, and it is generally applicable to any two-camera measurement. This type of imaging system offers the potential for recording simultaneously not only transmembrane potential and intracellular calcium, two frequently measured quantities, but also other signals more directly related to myocardial metabolism, such as [K(+)](e), NADH, and reactive oxygen species, leading to the possibility of correlative multimodal cardiac imaging. We provide a compilation of dye and camera information critical to the design of dual camera systems and experiments.

Forward-looking intracardiac ultrasound imaging using a 1-D CMUT array integrated with custom front-end electronics

Minimally invasive catheter-based electrophysiological (EP) interventions are becoming a standard procedure in diagnosis and treatment of cardiac arrhythmias. As a result of technological advances that enable small feature sizes and a high level of integration, nonfluoroscopic intracardiac echocardiography (ICE) imaging catheters are attracting increasing attention. ICE catheters improve EP procedural guidance while reducing the undesirable use of fluoroscopy, which is currently the common catheter guidance method. Phased-array ICE catheters have been in use for several years now, although only for side-looking imaging. We are developing a forward-looking ICE catheter for improved visualization. In this effort, we fabricate a 24-element, fine-pitch 1-D array of capacitive micromachined ultrasonic transducers (CMUT), with a total footprint of 1.73 mm x 1.27 mm. We also design a custom integrated circuit (IC) composed of 24 identical blocks of transmit/ receive circuitry, measuring 2.1 mm x 2.1 mm. The transmit circuitry is capable of delivering 25-V unipolar pulses, and the receive circuitry includes a transimpedance preamplifier followed by an output buffer. The CMUT array and the custom IC are designed to be mounted at the tip of a 10-Fr catheter for high-frame-rate forward-looking intracardiac imaging. Through-wafer vias incorporated in the CMUT array provide access to individual array elements from the back side of the array. We successfully flip-chip bond a CMUT array to the custom IC with 100% yield. We coat the device with a layer of polydimethylsiloxane (PDMS) to electrically isolate the device for imaging in water and tissue. The pulse-echo in water from a total plane reflector has a center frequency of 9.2 MHz with a 96% fractional bandwidth. Finally, we demonstrate the imaging capability of the integrated device on commercial phantoms and on a beating ex vivo rabbit heart (Langendorff model) using a commercial ultrasound imaging system.

Validation of QwikStar Catheter for left ventricular electromechanical mapping with NOGA XP system

Left ventricular electromechanical mapping (LVEM) is a method for mapping the left ventricular cavity in 3 dimensions by use of a catheter that samples points on the endocardial surface. These points provide data on unipolar voltage and linear local shortening, which can then be used to evaluate myocardial ischemia and viability. The new QwikStar multi-electrode catheter, which acquires data from multiple points simultaneously, potentially improves map quality and decreases mapping time in comparison with the single-point NogaStar catheter. Our study sought to validate the QwikStar catheter's LVEM capabilities in a porcine model of chronic ischemia.Eight pigs underwent ameroid placement over the proximal left circumflex artery, to induce chronic ischemia. In 60 days, LVEM was performed on each animal with the NogaStar and QwikStar catheters. Unipolar voltage and linear local shortening results were displayed in 9-segment polar maps. The unipolar voltage data from both maps were then correlated by means of linear regression.There were no adverse events during LVEM. Mapping time was similar for both groups (QwikStar, 44.6 +/- 25.62 min; NogaStar, 65.75 +/- 25.33 min; P = 0.13). Results of mean unipolar voltage maps acquired with the 2 catheters showed a moderate correlation (r =0.59, P <0.001). Selecting segments with more than 6 point samples increased the Pearson coefficient to 0.69 (P <0.001).Our findings show that the QwikStar catheter enables the reproducible performance of LVEM by sampling fewer points, which shortens procedure time, decreases manipulation of the left ventricular cavity, and might increase procedural safety.

Epicardial potential distribution reconstruction from recordings of intravenous and transthoracic mapping catheters: A feasibility study

Catheter-based epicardial mapping is possible with two access methods: transthoracic pericardial access and transvenous access. Transthoracic pericardial access is based on the introduction of the catheters into the pericardial space using a percutaneous subxiphoid puncture and may at times require lengthy sequential mapping procedures. From the transthoracic pericardial approach major regions of the epicardium may also be inaccessible. Transvenous access uses the multielectrode (4-20 electrodes) catheters placed in the coronary veins thus increases the speed of the mapping procedure, however, leaves most of the epicardium inaccessible to direct measurement. The aim of this present study is to demonstrate that the reconstruction of the high-resolution maps using sparse measurements from different sites on the epicardium and on the multielectrode catheters is possible with a reasonably high accuracy in terms of locating the origin of the ventricular arrhythmia. In this study we investigated strategies for the reconstruction of epicardial potential distribution from recordings of intravenous and transthoracic epicardial mapping catheters, alone and in combination. For this purpose, we first examined the problem of best number of epicardial measurement sites (or best sampling resolution) using transthoracic mapping catheters and secondly studied the feasibility of the combined usage of both mapping approaches. In the prediction of the surrogate measurements at inaccessible sites from the measurements localized to the cardiac veins and sparse epicardial sites we evaluated two prediction methods: the Laplacian interpolation and statistical estimation, to overcome the sparsity of the measurements. We performed 14 dog experiments with various interventions to create a high-resolution epicardial potential map database. This database included a total of 592 beats which were recorded using a sock array placed on the ventricles of dog hearts. We found that 2 cm sampling resolution is quite feasible, which means that the time for the mapping procedure may be reduced considerably. Predictions from the combination of 21 intravenous catheter leads and 30 transthoracic catheter leads were better than when only 21 or 30 leads were used. The results of this study encourage further investigation and provide adequate evidence that an epicardial mapping approach based on the combined usage of transvenous and transthoracic pericardial access methods for the mapping of the outer surface of the heart is feasible and can provide adequate accuracy for clinical applications.

Towards automation of a valuable preclinical cardiac safety pharmacology assay: Evaluation of the effects of cardiac ion channel blockers on cardiac repolarisation in vitro

INTRODUCTION

Purkinje fibre repolarisation assays are valuable tools for identifying compounds which affect cardiac ion channels. The throughput of compound testing in this assay is low therefore we designed a novel recording system to improve screening and animal tissue usage efficiencies.

METHODS

The system was used to evaluate compounds using standard sharp microelectrode techniques. Animal tissue usage efficiencies were quantified by adding up the total number of Purkinje fibres from which recordings were attempted and dividing this by the number of experimental data sets generated, to arrive at a 'fibres per data set' ratio. Test compounds were dofetilide (3 x 10(-10) to 10(-8) M), cisapride (10(-8) to 3 x 10(-7) M), terodiline (10(-6) to 3 x 10(-5) M) and verapamil (3 x 10(-7) to 10(-5) M).

RESULTS

Using the novel modified system, 21 data sets were generated from 29 fibres, compared to 24 data sets from 41 fibres using the conventional manual recording system, demonstrating a 24% improvement in the efficiency of animal tissue usage. Comparing data from the manual and modified systems revealed differences in absolute values for all parameters including APD90 (308.73 +/- 9.97 ms, n = 24, compared to 275.27 +/- 8.25 ms, n = 21, respectively; P < 0.05). Differences in the magnitude of changes in action potential parameters between the systems were also evident for all compounds including terodiline (1 x 10(-5) M) which caused a -27.1 +/- 16.5% reduction in APD50 in the manual system, compared to a - 55.2 +/- 2.2% reduction in the modified system.

DISCUSSION

Although the value of the present study is limited by the small sample sizes, it has demonstrated utility of the modified system in improving efficiency of animal tissue usage. It offers potential utility in a higher throughput screening environment for examining the electrophysiological properties of novel compounds in native cardiac tissues, particularly where functional patch clamp data are limited.

[Study and investigation of mechanism of atrial fibrillation--(I) High resolution cardiac mapping system]

This paper introduces the history and background of studies on the mechanism of atrial fibrillation. The necessary equipment to study atrial fibrillation--a high-resolution cardiac mapping system is presented. This equipment has provided a strong basis for the future study to acquire a precise understanding of the mechanism of atrial fibrillation.

Optical mapping system with real-time control capability

Real-time, closed-loop intervention is an emerging experiment-control method that promises to provide invaluable new insight into cardiac electrophysiology. One example is the investigation of closed-loop feedback control of cardiac activity (e.g., alternans) as a possible method of preventing arrhythmia onset. To date, such methods have been investigated only in vitro using microelectrode systems, which are hindered by poor spatial resolution and are not well suited for atrial or ventricular tissue preparations. We have developed a system that uses optical mapping techniques and an electrical stimulator as the sensory and effector arms, respectively, of a closed-loop, real-time control system. The system consists of a 2,048 x 1 pixel line-scan charge-coupled device camera that records optical signals from the tissue. Custom-image processing and control software, which is implemented on top of a hard real-time operation system (RTAI Linux), process the data and make control decisions with a deterministic delay of <1 ms. The system is tested in two ways: 1) it is used to control, in real time, simulated optical signals of electrical alternans; and 2) it uses precisely timed, feedback-controlled initiation of antitachycardia pacing to terminate reentrant arrhythmias in an arterially perfused swine right ventricle stained with voltage-sensitive fluorescent dye 4{beta-[2-(di-n-butylamino)-6-napathy]vinyl}pyridinium (di-4-ANEPPS). Thus real-time control of cardiac activity using optical mapping techniques is feasible. Such a system is attractive because it offers greater measurement resolution than the electrode-based systems with which real-time control has been used previously.

Non-fluoroscopic catheter-based mapping systems in cardiac electrophysiology--from approved clinical indications to novel research usage

BACKGROUND

During 20 years of development of catheter-based technologies in the management of cardiac arrhythmias, electrophysiological mapping/ablation systems have evolved from single-plane fluoroscopic mapping to three-dimensional (3-D) non-fluoroscopic computer-based mapping systems.

METHODS

Based on magnetic technology, the electro-anatomic CARTO mapping system can accurately correlate local electrograms with recording sites, by which the system can reconstruct 3-D maps with colour-coded electrophysiological information superimposed on the anatomy. Whereas the CARTO system is primarily designed for studying cardiac activation and not repolarisation, the system has been widely used in the diagnosis and ablation of cardiac arrhythmias and in the research of basic arrhythmic mechanisms.

RESULTS

In order to study cardiac repolarisation in vivo, an innovative method, the monophasic action potential (MAP) mapping technique, which integrates MAP recording with electroanatomical mapping, has recently been developed in our centre. Using the MAP technique, global sequence and dispersion of atrial/ventricular repolarisation have been evaluated in vivo in both experimental and clinical settings.

CONCLUSION

The innovative MAP technique provides unique research opportunities for in vivo studies of basic electrophysiological mechanisms.

Noncontact three-dimensional mapping guides catheter ablation of difficult atrioventricular nodal reentrant tachycardia

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia in adulthood. Although selective ablation of the slow AV nodal pathway can cure AVNRT, accidental AV block may occur. The details on the electrophysiologic characteristics, quantitative data on the voltage inside Koch's triangle, and the use of three-dimensional noncontact mapping to facilitate the catheter ablation of AVNRT associated with a high-risk for AV block or other arrhythmias have been limited.

METHODS AND RESULTS

Nine patients (M/F=5/4, 34+/-23 years, range 17-76) with clinically documented AVNRT were included. All patients had undergone previous sessions for slow AV nodal pathway ablation but they had failed, because of repetitive episodes of complete AV block during the RF energy applications. Further, one patient had a complex anatomy and 4 patients were associated with other tachycardias, respectively. The electrophysiologic studies revealed that 4 patients had the slow-fast, 4 the slow-intermediate and one the fast-intermediate form of AVNRT. Noncontact mapping demonstrated two types of antegrade AV nodal conduction, markedly differing sites of the earliest atrial activation during retrograde VA conduction, and a lower range of voltage within Koch's triangle. The lowest border of the retrograde conduction region was defined on the map, and the application of the RF energy was delivered below that border to prevent the occurrence of AV block. The distance between the successful ablation lesions and the lowest border of the retrograde conduction region was significantly shorter in the patients with the slow-intermediate form of AVNRT than in those with the slow-fast form (5.5+/-3.4 vs. 15+/-7.6 mm; p<0.05). After the ablation procedure, either rapid pacing or extrastimulation could not induce any tachycardia, and there was no recurrence during the follow-up (10.3+/-5.4, 2 to 22 months).

CONCLUSIONS

Noncontact mapping could effectively demonstrate the antegrade and retrograde atrionodal conduction patterns, electrophysiologic characteristics of Koch's triangle, and guide the successful catheter ablation in difficult AVNRT cases.

A NavX-guided ablation of a nodo-fascicular fibre

The NavX system was used to guide mapping and successful ablation of a reciprocating antidromic tachycardia involving anterograde conduction over a nodo-fascicular fibre and retrograde conduction over the His bundle and AV node. This novel mapping system allowed visualization of the lower insertion site of the nodo-fascicular accessory pathway approximately 1.5-2 cm away from the tricuspid annulus in a three-dimensional reconstruction of the right atrium and right ventricle.

Radiofrequency Ablation of the Ventricular Tachycardia with Arrhythmogenic Right Ventricular Cardiomyopathy Using Non-contact Mapping

BACKGROUND

Intracardiac non-contact mapping provides a rapid and accurate isopotential mapping that facilitates catheter ablation of the ventricular tachyarrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS

Thirty-two consecutive patients (26 men and 6 women, mean 37.2 +/- 13.8 years) were treated with ablation. Fourteen patients had a history of syncope/pre-syncope. Two patients had an implantable cardiac defibrillator (ICD) previously implanted.

RESULTS

There were 67 ventricular tachycardias (VTs) induced in the 32 patients. The average VT rate was 210 +/- 32.2 (130-310) bpm. There were 42 episodes of VT that had a heart rate > or =200 bpm and 24 of the 32 patients (75%) had > or =2 morphologies of VT. Regional ablation was applied by targeting the earliest VT activation sites under the guidance of non-contact mapping. Acute success was achieved in 84.4% (27/32) patients, and significant improvement was seen in 15.6% (5/32) patients as evidenced by a slower rate of VT. None of the patients experienced syncope/pre-syncope or sudden death during the 28.6 +/- 16 (9-72) month follow-up. There were no complications of the procedure. At the end of follow-up, 81.3% of the patients were free of VT without medication while the rest of the patients achieved a modified success.

CONCLUSIONS

The rapid ventricular tachyarrhythmias in ARVC patients can be abolished or improved significantly by regional RF catheter ablation under the guidance of non-contact mapping. There was no sudden cardiac arrest or death in those patients without ICD implantation. Delayed efficacy may occur in some patients after ablation.

Elimination of Fluoroscopy Use in a Pediatric Electrophysiology Laboratory Utilizing Three-Dimensional Mapping

OBJECTIVES

The aim of this study was to quantify fluoroscopy use in catheter ablation procedures using a three-dimensional mapping system as the primary source of catheter guidance.

BACKGROUND

Three-dimensional mapping allows continuous visualization of the location of mapping and ablation catheter electrodes. It has been shown to decrease fluoroscopy times. However, the extent to which it can decrease fluoroscopy time has not been completely defined.

METHODS

Thirty patients (mean age 12.9 years; range 4-27 years) with reentrant supraventricular tachycardia underwent catheter ablation using standard protocols. Mapping was performed using the EnSite system (St. Jude Medical, St Paul, MN, USA) in the NavX mode (NavX). Eighteen patients had AVNRT, 12 had AVRT. Fluoroscopy times were compared to an age-matched and rhythm-matched control population.

RESULTS

Procedural success was achieved in 30 of 30 patients (100%). Mean procedure time was 3.27 hours (range 1.83-5.8 hours). Mean fluoroscopy time was 1.05 minutes (range 0-14.8 minutes). Twenty-four of 30 (80%) received no fluoroscopy. Mean fluoroscopy time for the control group was 21.37 minutes (range 5.13-77.13 minutes). Thus fluoroscopy time was 95% less in the study group compared to control (1.05 +/- 2.96 vs 21.37 +/- 18.35 minutes, P < 0.001).

CONCLUSIONS

NavX was used to effectively guide catheters during ablation procedures resulting in a significant decrease in fluoroscopy use. In 80% of the procedures, no fluoroscopy was used. Further advances in the technology may permit additional decreases in x-ray exposure for the 20% of patients who required it.

A Nonfluoroscopic Approach for Electrophysiology and Catheter Ablation Procedures Using a Three-Dimensional Navigation System

BACKGROUND

Three-dimensional (3D) electroanatomical navigation systems decrease the fluoroscopy time of electrophysiology and ablation procedures. The aim of this study was to assess the safety and efficacy of a complete nonfluoroscopic approach for electrophysiologic studies and right-sided catheter ablations for supraventricular tachycardia in patients with normal cardiac anatomy using a 3D, surface electrode-based navigation system (NavX, St. Jude Medical, St. Paul, MN, USA).

METHODS AND RESULTS

Electrophysiologic studies were performed in 26 consecutive cases (12.7 +/- 7.5 years) using NavX without fluoroscopy. The procedure time was 98.7 +/- 49.7 minutes. Nonfluoroscopic catheter ablations were performed in 24 of 28 consecutive patients. Cryoablation was used in 23 of 24. The procedure time was 193.5 +/- 80 minutes. The coronary sinus access was obtained in 32.1 +/- 12 (range: 15-60) seconds. No complications occurred. All patients (n = 19) who underwent cryoablation for right-sided arrhythmia substrates with conventional fluoroscopic guidance in addition to NavX were used as a control group (10.1 +/- 5.2 years). Catheter ablation success rate of the control group (16/19, 84%) was not significantly different compared to the patients who underwent ablation without fluoroscopy (22/24, 92%). The procedure time was also not significantly different between the two groups (P = NS).

CONCLUSION

This study demonstrates that nonfluoroscopic electrophysiologic studies and right-sided catheter ablations for supraventricular tachycardia can be safely and effectively performed in the majority of patients with normal cardiac anatomy using NavX. Further studies will be necessary in order to establish the potential utility of NavX in eliminating or decreasing radiation exposure for other electrophysiology procedures.

Patterns of activation in human atrial fibrillation

The electrophysiological properties within the pulmonary vein (PV) and PV-left atrial (LA) junction were evaluated using a basket catheter in patients with paroxysmal atrial fibrillation. The effective refractory period of the distal PV was significantly shorter than that of the PV-LA junction. The conduction delay from the distal to proximal PV was significantly longer than that from the proximal to distal PV. During initiation of AF, a reentry involving exit and entrance breakthrough points at the PV-LA junction was observed. The presence of anisotropic conduction properties at the PV-LA junction may be critical to promote reentry formation.

Basic algorithms for the programming of deep brain stimulation in Parkinson's disease

The clinical success of deep brain stimulation (DBS) for treating Parkinson's disease (PD) critically depends on the quality of postoperative neurological management. Movement disorder specialists becoming involved with this therapy need to acquire new skills to adapt optimally stimulation parameters and medication after implantation of a DBS system. At first glance, the infinite number of theoretically possible parameter combinations seems to make programming a complex and time-consuming art. This article outlines a stepwise and standardized approach, reducing the possible parameter settings in DBS to a few relevant combinations. The basic programming algorithms for thalamic, subthalamic, and pallidal stimulation in PD are explained and summarized in flowcharts.

Dynamic clamp: a powerful tool in cardiac electrophysiology

Dynamic clamp is a collection of closely related techniques that have been employed in cardiac electrophysiology to provide direct answers to numerous research questions regarding basic cellular mechanisms of action potential formation, action potential transfer and action potential synchronization in health and disease. Building on traditional current clamp, dynamic clamp was initially used to create virtual gap junctions between isolated myocytes. More recent applications include the embedding of a real pacemaking myocyte in a simulated network of atrial or ventricular cells and the insertion of virtual ion channels, either simulated in real time or simultaneously recorded from an expression system, into the membrane of an isolated myocyte. These applications have proven that dynamic clamp, which is characterized by the real-time evaluation and injection of simulated membrane current, is a powerful tool in cardiac electrophysiology. Here, each of the three different experimental configurations used in cardiac electrophysiology is reviewed. Also, directions are given for the implementation of dynamic clamp in the cardiac electrophysiology laboratory. With the growing interest in the application of dynamic clamp in cardiac electrophysiology, it is anticipated that dynamic clamp will also prove to be a powerful tool in basic research on biological pacemakers and in identification of specific ion channels as targets for drug development.

Volume measurement by CARTO compared with cardiac magnetic resonance

AIMS

The CARTO electrophysiological mapping system has demonstrated accurate results for end-diastolic ventricular volumes in casts and animals. However, in humans, a comparison with cardiac magnetic resonance (CMR), the non-invasive gold standard for volumetric analysis, has not yet been performed.

METHODS AND RESULTS

A total of 34 (29 male) heart failure patients (NYHA class III/IV) underwent an electrophysiological mapping procedure with the CARTO system in the left ventricle (LV) (n = 34) and right ventricle (RV) (n = 12) and CMR for RV and LV end-diastolic volume (RVEDV and LVEDV) measurements another day. Mean LVEDV was comparable between CMR and CARTO (328 +/- 95 and 320 +/- 92 mL, respectively; P = NS), whereas RV volumes measured by CARTO were larger (CMR 140 +/- 48 vs. CARTO 176 +/- 47 mL; P < 0.01). Overall, we found a good correlation between CMR and CARTO measurements for both chambers; however, the Bland-Altman analysis showed a non-interchangeability of these methods. Measurement differences were independent of chamber size, but significantly affected by the number of acquired mapping points.

CONCLUSION

Although CMR and CARTO showed a good correlation in the measurement of RVEDV and LVEDV in a group of heart failure patients, the clinical interchangeability of the two methods may be questioned.

Evaluation of a radiation protection cabin for invasive electrophysiological procedures

AIMS

Complex invasive electrophysiological procedures may result in high cumulative operator radiation exposure. Classical protection with lead aprons results in discomfort while radioprotection is still incomplete. This study evaluated the usefulness of a radiation protection cabin (RPC) that completely surrounds the operator.

METHODS AND RESULTS

The evaluation was performed independently in two electrophysiology laboratories (E1-Leuven, Belgium; E2-Bordeaux, France), comparing operator radiation exposure using the RPC vs. a 0.5 mm lead-equivalent apron (total of 135 procedures). E1 used thermoluminiscent dosimeters (TLDs) placed at 16 positions in and out of the RPC and nine positions in and out of the apron. E2 used more sensitive electronic personal dosimeters (EPD), placed at waist and neck. The sensitivity thresholds of the TLDs and EPDs were 10-20 microSv and 1-1.5 microSv, respectively. All procedures could be performed unimpeded with the RPC. Median TLD dose values outside protected areas were in the range of 57-452 microSv, whereas doses under the apron or inside the RPC were all at the background radiation level, irrespective of procedure and fluoroscopy duration and of radiation energy delivered. In addition, the RPC was protecting the entire body (except the hands), whereas lead apron protection is incomplete. Also with the more sensitive EPDs, the radiation dose within the RPC was at the sensitivity threshold/background level (1.3+/-0.6 microSv). Again, radiation to the head was significantly lower within the RPC (1.9+/-1.2 microSv) than with the apron (102+/-23 microSv, P<0.001).

CONCLUSION

The use of the RPC allows performing catheter ablation procedures without compromising catheter manipulation, and with negligible radiation exposure for the operator.