Clinical experience with a novel multielectrode basket catheter in right atrial tachycardias

Design, Testing, and Validation of a Soft Robotic Sensor Array Integrated with Flexible Electronics for Mapping Cardiac Arrhythmias

Cardiac mapping is a crucial procedure for diagnosing and treating cardiac arrhythmias. Still, current clinical techniques face limitations including insufficient electrode coverage, poor conformability to complex heart chamber geometries, and high costs. This study explores the design, testing, and validation of a 64-electrode soft robotic catheter that addresses these challenges in cardiac mapping. A dual-layer flexible printed circuit board (PCB) was designed and integrated with sensors into a soft robotic sensor array (SRSA) assembly. Design considerations included flex PCB layout, routing, integration, conformity to heart chambers, sensor placement, and catheter durability. Rigorous SRSA in vitro testing evaluated the burst/leakage pressure, block force for electrode contact, mechanical integrity, and environmental resilience. For in vivo validation, a porcine model was used to demonstrate the successful deployment, conformability, and acquisition of electrograms in both the ventricles and atria. This catheter-deployable SRSA represents a meaningful step towards translating the integration of soft robotic actuators and stretchable electronics for clinical use, showcasing the unique mechanical and electrical performance that these designs enable. The high-density electrode array enabled rapid 2 s data acquisition with detailed spatial and temporal resolution, as illustrated by the clear and consistent cardiac signals recorded across all electrodes. The future of this work will lie in enabling high-density, anatomically conformable devices for detailed cardiac mapping to guide ablation therapy and other interventions.

Multilayer fabrication of durable catheter-deployable soft robotic sensor arrays for efficient left atrial mapping

Devices that perform cardiac mapping and ablation to treat atrial fibrillation provide an effective means of treatment. Current devices, however, have limitations that either require tedious point-by-point mapping of a cardiac chamber or have limited ability to conform to the complex anatomy of a patient's cardiac chamber. In this work, a detailed, scalable, and manufacturable technique is reported for fabrication of a multielectrode, soft robotic sensor array. These devices exhibit high conformability (~85 to 90%) and are equipped with an array of stretchable electronic sensors for voltage mapping. The form factor of the device is intended to match that of the entire left atrium and has a hydraulically actuated soft robotic structure whose profile facilitates deployment from a 13.5-Fr catheter. We anticipate that the methods described in this paper will serve a new generation of conformable medical devices that leverage the unique characteristics of stretchable electronics and soft robotics.

Basket-Type Catheters: Diagnostic Pitfalls Caused by Deformation and Limited Coverage

Whole-chamber mapping using a 64-pole basket catheter (BC) has become a featured approach for the analysis of excitation patterns during atrial fibrillation. A flexible catheter design avoids perforation but may lead to spline bunching and influence coverage. We aim to quantify the catheter deformation and endocardial coverage in clinical situations and study the effect of catheter size and electrode arrangement using an in silico basket model. Atrial coverage and spline separation were evaluated quantitatively in an ensemble of clinical measurements. A computational model of the BC was implemented including an algorithm to adapt its shape to the atrial anatomy. Two clinically relevant mapping positions in each atrium were assessed in both clinical and simulated data. The simulation environment allowed varying both BC size and electrode arrangement. Results showed that interspline distances of more than 20 mm are common, leading to a coverage of less than 50% of the left atrial (LA) surface. In an ideal in silico scenario with variable catheter designs, a maximum coverage of 65% could be reached. As spline bunching and insufficient coverage can hardly be avoided, this has to be taken into account for interpretation of excitation patterns and development of new panoramic mapping techniques.

A novel retractable laparoscopic device for mapping gastrointestinal slow wave propagation patterns

BACKGROUND

Gastric slow waves regulate peristalsis, and gastric dysrhythmias have been implicated in functional motility disorders. To accurately define slow wave patterns, it is currently necessary to collect high-resolution serosal recordings during open surgery. We therefore developed a novel gastric slow wave mapping device for use during laparoscopic procedures.

METHODS

The device consists of a retractable catheter constructed of a flexible nitinol core coated with Pebax. Once deployed through a 5-mm laparoscopic port, the spiral head is revealed with 32 electrodes at 5 mm intervals. Recordings were validated against a reference electrode array in pigs and tested in a human patient.

RESULTS

Recordings from the device and a reference array in pigs were identical in frequency (2.6 cycles per minute; p = 0.91), and activation patterns and velocities were consistent (8.9 ± 0.2 vs 8.7 ± 0.1 mm s^-1; p = 0.2). Device and reference amplitudes were comparable (1.3 ± 0.1 vs 1.4 ± 0.1 mV; p = 0.4), though the device signal-to-noise ratio was higher (17.5 ± 0.6 vs 12.8 ± 0.6 dB; P < 0.0001). In the human patient, corpus slow waves were recorded and mapped (frequency 2.7 ± 0.03 cycles per minute, amplitude 0.8 ± 0.4 mV, velocity 2.3 ± 0.9 mm s^-1).

CONCLUSION

In conclusion, the novel laparoscopic device achieves high-quality serosal slow wave recordings. It can be used for laparoscopic diagnostic studies to document slow wave patterns in patients with gastric motility disorders.

On the efficiency and accuracy of the single equivalent moving dipole method to identify sites of cardiac electrical activation

We have proposed an algorithm to guide radiofrequency catheter ablation procedures. This algorithm employs the single equivalent moving dipole (SEMD) to model cardiac electrical activity. The aim of this study is to investigate the optimal time instant during the cardiac cycle as well as the number of beats needed to accurately estimate the location of a pacing site. We have evaluated this algorithm by pacing the ventricular epicardial surface and inversely estimating the locations of pacing electrodes from the recorded body surface potentials. Two pacing electrode arrays were sutured on the right and left ventricular epicardial surfaces in swine. The hearts were paced by the electrodes sequentially at multiple rates (120-220 bpm), and body surface ECG signals from 64 leads were recorded for the SEMD estimation. We evaluated the combined error of the estimated interelectrode distance and SEMD direction at each time instant during the cardiac cycle, and found the error was minimum when the normalized root mean square (RMS n ) value of body surface ECG signals reached 15 % of its maximum value. The beat-to-beat variation of the SEMD locations was significantly reduced (p < 0.001) when estimated at 15 % RMS n compared to the earliest activation time (EAT). In addition, the 5-95 % interval of the estimated interelectrode distance error decreased exponentially as the number of beats used to estimate a median beat increased. When the number of beats was 4 or larger, the 5-95 % interval was smaller than 3.5 mm (the diameter of a commonly used catheter). In conclusion, the optimal time for the SEMD estimation is at 15 % of RMS n , and at that time instant a median beat estimated from 4 beats is associated with a beat-to-beat variability of the SEMD location that is appropriate for catheter ablation procedures.

Rapid Mapping of Right Atrial Tachycardia Using a New Multielectrode Basket Catheter

INTRODUCTION

The mapping of atrial tachycardia (AT) can often be challenging and time-consuming, especially in patients with ATs that develop following cardiac surgery or are concomitant with atrial fibrillation. Recently, a new multielectrode basket catheter (MBC) has become available; we hypothesized that the MBC could be utilized to diagnose AT circuits.

METHODS AND RESULTS

This study included 51 consecutive patients undergoing catheter ablation of clinically documented right-sided ATs (including 17 cases following cardiac surgery). Using a NavX system, 2 activation maps of the ATs were created, one using the new MBC (32 mm, 31 poles) and the other using a circular catheter. The time needed to complete the activation maps and the points acquired with both mapping catheters were compared. In all 64 ATs, including 34 non-cavotricuspid isthmus-dependent ATs, the AT activation maps created by both catheters were essentially identical. The number of points acquired to complete the activation maps did not differ significantly between the MBC and the circular catheter (387 [285-511] vs. 374 [269-533], P = 0.19), but the mapping time was significantly shorter using the MBC (4.0 [3.0-6.0] minutes vs. 8.0 [6.5-10.0] minutes, P < 0.0001). Inadvertent mechanical AT termination (n = 6) was observed only during mapping with the circular catheter.

CONCLUSION

In patients with right-sided ATs, the use of an MBC could save mapping time.

Radiofrequency ablation of cardiac arrhythmias: past, present and future

The treatment of cardiac arrhythmias has been revolutionized by the ability to definitively treat many patients with radiofrequency catheter ablation, rather than requiring lifelong medication. This review covers the history of how this has developed and the methods used currently and explores what the future holds for this rapidly evolving branch of Cardiology.

Construction of 3D MR image-based computer models of pathologic hearts, augmented with histology and optical fluorescence imaging to characterize action potential propagation

Cardiac computer models can help us understand and predict the propagation of excitation waves (i.e., action potential, AP) in healthy and pathologic hearts. Our broad aim is to develop accurate 3D MR image-based computer models of electrophysiology in large hearts (translatable to clinical applications) and to validate them experimentally. The specific goals of this paper were to match models with maps of the propagation of optical AP on the epicardial surface using large porcine hearts with scars, estimating several parameters relevant to macroscopic reaction-diffusion electrophysiological models. We used voltage-sensitive dyes to image AP in large porcine hearts with scars (three specimens had chronic myocardial infarct, and three had radiofrequency RF acute scars). We first analyzed the main AP waves' characteristics: duration (APD) and propagation under controlled pacing locations and frequencies as recorded from 2D optical images. We further built 3D MR image-based computer models that have information derived from the optical measures, as well as morphologic MRI data (i.e., myocardial anatomy, fiber directions and scar definition). The scar morphology from MR images was validated against corresponding whole-mount histology. We also compared the measured 3D isochronal maps of depolarization to simulated isochrones (the latter replicating precisely the experimental conditions), performing model customization and 3D volumetric adjustments of the local conductivity. Our results demonstrated that mean APD in the border zone (BZ) of the infarct scars was reduced by ~13% (compared to ~318 ms measured in normal zone, NZ), but APD did not change significantly in the thin BZ of the ablation scars. A generic value for velocity ratio (1:2.7) in healthy myocardial tissue was derived from measured values of transverse and longitudinal conduction velocities relative to fibers direction (22 cm/s and 60 cm/s, respectively). The model customization and 3D volumetric adjustment reduced the differences between measurements and simulations; for example, from one pacing location, the adjustment reduced the absolute error in local depolarization times by a factor of 5 (i.e., from 58 ms to 11 ms) in the infarcted heart, and by a factor of 6 (i.e., from 60 ms to 9 ms) in the heart with the RF scar. Moreover, the sensitivity of adjusted conductivity maps to different pacing locations was tested, and the errors in activation times were found to be of approximately 10-12 ms independent of pacing location used to adjust model parameters, suggesting that any location can be used for model predictions.

Fusion of optical imaging and MRI for the evaluation and adjustment of macroscopic models of cardiac electrophysiology: a feasibility study

The aim of this work was to demonstrate the correspondence between a macroscopic 3D computer model of electrophysiology (i.e., the Aliev-Panfilov model) parametrized with MR data and experimental characterization of action potential propagation in large porcine hearts, ex vivo, using optical methods (based on voltage-sensitive fluorescence). A secondary goal was to use one of these studies to demonstrate an optimized method for regional adjustment of critical model parameters (i.e., adjustment of the local conductivity from the isochronal maps obtained via optical images). There was good agreement between model behaviour and experiment using fusion of optical and MR data, and model parameters from previous work in the literature. Specifically, qualitative comparison between computed and measured activation maps gave good results. Adjustment of the conductivity parameter within 26 regions fitting data from the current experiments in one heart reduced absolute error in local depolarization times by a factor of 3 (i.e. from 30 to 10 ms).

Focal Atrial Tachycardias Arising from the Right Atrial Appendage: Electrocardiographic and Electrophysiologic Characteristics and Radiofrequency Ablation

OBJECTIVE

To characterize the electrocardiographic and electrophysiological features and frequency of focal atrial tachycardia (AT) originating from the right atrial appendage (RAA).

BACKGROUND

The RAA has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited.

METHODS

Ten patients (3.8%) of 261 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), tricuspid annulus (20 pole Halo catheter), and His positions. P waves were classified as negative, positive, isoelectric, or biphasic.

RESULTS

The mean age was 39 +/- 20 years, nine males, with symptoms for 4.1 +/- 5.1 years. Tachycardia was incessant in seven patients, spontaneous in one patient, and induced by programmed extrastimuli in two patients. These foci had a characteristic P wave morphology. The P wave was negative in lead V(1) in all patients, becoming progressively positive across the precordial leads. The P waves in the inferior leads were low amplitude positive in the majority of patients. Earliest EAM activity occurred on the Halo catheter in all patients. Mean activation time at the successful RFA site =-38 +/- 15 msec. Irrigated catheters were used in six patients, due to difficulty achieving adequate power. RFA was acutely successful in all patients. Long-term success was achieved in all patients over a mean follow up of 8 +/- 7 months.

CONCLUSIONS

The RAA is an uncommon site of origin for focal AT (3.8%). It can be suspected as a potential anatomic site of AT origin from the characteristic P wave and activation timing. Irrigated ablation catheters are often required for successful ablation. Long-term success was achieved with focal ablation in all patients.

[Right atrial ablation of ectopic atrial tachycardia using a 20-pole mapping catheter]

INTRODUCTION

Ectopic atrial tachycardia (EAT) are frequently unresponsive to pharmacological antiarrhythmic therapy. Radiofrequency ablation seems to be a safe approach to treat those arrhythmias. In the present study we report our results of radiofrequency ablation of EAT with a new mapping system (Stablemapr, Medtronic).

METHODS

Thirty consecutive patients with right atrial tachycardia were included in the study. In 15 patients (G1) the 20-polar Stablemapr was used for localization of the arrhythmia foci. Data were compared with a control group (G2, n=15), in which mapping was performed conventionally. The demographic characteristics and the distribution of the different cardiac diseases were comparable in both groups. In group 1 the identification of the EAT was facilitated by the placement of the 20-pole mapping catheter in the right atrium. In group 2 point by point measurements were performed to find the earliest local atrial activation compared to a reference electrode in the high right atrium (activation mapping), or foci were identified by analysis of the P-wave morphology during stimulation (pacemapping).

RESULTS

It was possible to successfully ablate all atrial tachycardias. The distribution of the foci was similar in both groups (G1/G2): near to the superior (3/5) and inferior (1/0) caval vene ostium, on the free wall (3/3), at the coronary sinus ostium (3/3) and on the interatrial septum (5/4). The mean procedure (G1: 88+/-33 vs G2: 151+/-61 min; p= or <0.05) and fluoroscopic times (G1: 19+/-9 vs G2: 38+/-28 min; p= or <0.05) were significantly shorter in group 1. Moreover, the mean number of radiofrequency applications was reduced significantly by using the new mapping system (G1: 10+/-10 vs G2: 16+/-13; p= or <0.05).

CONCLUSION

Radiofrequency ablation of EAT with right atrial focus can be performed safely and successfully using a 20-pole mapping catheter. The greatest advantages compared to conventional mapping and ablation strategies lies in the shortened investigation and fluoroscopic time.

Focal Atrial Tachycardia II: Management

Over the last decade there have been significant changes in the treatment of focal atrial tachycardia (AT). This review concentrates on the different approaches to the treatment of focal AT. Initial therapies included antiarrhythmic medications and surgery. However, with the advent of radiofrequency ablation, and the poor efficacy of pharmacological therapy, there has been a shift toward a primary ablative approach. Several different mapping techniques have been proposed. The different techniques, including P-wave morphology and advanced three-dimensional mapping, are discussed in this review.

Cardiac function estimation from MRI using a heart model and data assimilation: advances and difficulties

In this paper, we present a framework to estimate local ventricular myocardium contractility using clinical MRI, a heart model and data assimilation. First, we build a generic anatomical model of the ventricles including muscle fibre orientations and anatomical subdivisions. Then, this model is deformed to fit a clinical MRI, using a semi-automatic fuzzy segmentation, an affine registration method and a local deformable biomechanical model. An electromechanical model of the heart is then presented and simulated. Finally, a data assimilation procedure is described, and applied to this model. Data assimilation makes it possible to estimate local contractility from given displacements. Presented results on fitting to patient-specific anatomy and assimilation with simulated data are very promising. Current work on model calibration and estimation of patient parameters opens up possibilities to apply this framework in a clinical environment.

Characterization of Focal Atrial Tachycardia Using High-Density Mapping

OBJECTIVES

The goal of this study was to characterize the origin of focal atrial tachycardias (AT).

BACKGROUND

Focal ATs originate from a small area and spread centrifugally; however, activation at the AT origin has not been characterized.

METHODS

Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro-re-entry, AT was mapped using a 20-pole catheter (five radiating spines; diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment.

RESULTS

A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 +/- 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 +/- 19 ms vs. 64 +/- 22 ms, representing 49 +/- 10% and 20 +/- 10% of tachycardia CL, respectively; p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32%; p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 +/- 7 months, none have had recurrence of AT.

CONCLUSIONS

High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry.

A system for real-time XMR guided cardiovascular intervention

The hybrid magnetic resonance (MR)/X-ray suite (XMR) is a recently introduced imaging solution that provides new possibilities for guidance of cardiovascular catheterization procedures. We have previously described and validated a technique based on optical tracking to register MR and X-ray images obtained from the sliding table XMR configuration. The aim of our recent work was to extend our technique by providing an improved calibration stage, real-time guidance during cardiovascular catheterization procedures, and further off-line analysis for mapping cardiac electrical data to patient anatomy. Specially designed optical trackers and a dedicated calibration object have resulted in a single calibration step that can be efficiently checked and updated before each procedure. An X-ray distortion model has been implemented that allows for distortion correction for arbitrary c-arm orientations. During procedures, the guidance system provides a real-time combined MR/X-ray image display consisting of live X-ray images with registered recently acquired MR derived anatomy. It is also possible to reconstruct the location of catheters seen during X-ray imaging in the MR derived patient anatomy. We have applied our registration technique to 13 cardiovascular catheterization procedures. Our system has been used for the real-time guidance of ten radiofrequency ablations and one aortic stent implantation. We demonstrate the real-time guidance using two exemplar cases. In a further two cases we show how off-line analysis of registered image data, acquired during electrophysiology study procedures, has been used to map cardiac electrical measurements to patient anatomy for two different types of mapping catheters. The cardiologists that have used the guidance system suggest that real-time XMR guidance could have substantial value in difficult interventional and electrophysiological procedures, potentially reducing procedure time and delivered radiation dose. Also, the ability to map measured electrical data to patient specific anatomy provides improved visualization and a path to investigation of cardiac electromechanical models.

Catheter ablation of left atrial focal tachycardia guided by electroanatomic mapping and new insights into interatrial electrical conduction

BACKGROUND

Experience in catheter ablation of left atrial (LA) focal tachycardia and information about interatrial electrical connections during LA focal tachycardia are limited.

OBJECTIVES

The purpose of this study was to describe our experience in electroanatomic mapping-guided catheter ablation of LA focal tachycardia and to investigate interatrial electrical connections during LA focal tachycardias.

METHODS

Thirty-three patients undergoing catheter ablation for LA focal tachycardia guided by electroanatomic mapping were reported. Interatrial electrical connections were analyzed in LA focal tachycardias with biatrial electroanatomic maps.

RESULTS

Of the 35 LA focal tachycardias (cycle length 309 +/- 100 ms) mapped, 19 (54%) originated from the pulmonary veins (PVs), 6 (17%) from the mitral annulus, 3 (8.6%) from LA roof, 3 (8.6%) from LA posterior wall, 2 (5.7%) from LA appendage, and 2 (5.7%) from LA septum. Fourteen of the 19 PV tachycardias (74%) were located in proximity to PV ostia. In 14 (7 PV, 7 non-PV) LA focal tachycardias with biatrial electroanatomic maps, posterior right atrium breakthrough sites at the intercaval area were identified in 7 PV tachycardias and 1 non-PV tachycardia. Five of the 7 PV tachycardias used only the posterior breakthrough for interatrial propagation. Procedural success was achieved in 33 of 35 LA focal tachycardias (94%) in 31 patients. During 23 +/- 19 months of follow-up, 2 patients (6%) had recurrence of ablated tachycardia, and 3 (10%) developed new LA focal tachycardias.

CONCLUSIONS

The PVs and the mitral annulus were the main sources of LA focal tachycardias. The majority of PV tachycardias originated from PV ostia. A posterior interatrial connection appeared to play a major role in interatrial electrical propagation during PV tachycardias. Electroanatomic mapping facilitated precise localization of LA focal tachycardias and achievement of a high rate of ablation success.

Simulation of cardiac pathologies using an electromechanical biventricular model and XMR interventional imaging

Simulating cardiac electromechanical activity is of great interest for a better understanding of pathologies and for therapy planning. Design and validation of such models is difficult due to the lack of clinical data. XMR systems are a new type of interventional facility in which patients can be rapidly transferred between X-ray and MR systems. Our goal is to design and validate an electromechanical model of the myocardium using XMR imaging. The proposed model is computationally fast and uses clinically observable parameters. We present the integration of anatomy, electrophysiology, and motion from patient data. Pathologies are introduced in the model and simulations are compared to measured data. Initial qualitative comparison on the two clinical cases presented is encouraging. Once fully validated, these models will make it possible to simulate different interventional strategies.

Use of advanced mapping systems to guide ablation in complex cases: experience with noncontact mapping and electroanatomic mapping systems

OBJECTIVE

This report describes our experience with noncontact mapping and electroanatomic mapping in complex ablations, which are defined as ablations done after failure of conventional ablation.

MATERIAL AND METHODS

Patients were included (N = 68; 49% with structural heart disease) in whom previous ablation failed and in whom a second procedure was done with advanced mapping. Non-contact mapping was used in 17 patients, electroanatomic mapping in 36, and both noncontact and electroanatomic mapping in 15. Arrhythmias included focal atrial tachycardia (n = 16), reentrant atrial tachycardia (n = 14), right ventricular outflow tachycardia (n = 10), post-myocardial infarction ventricular tachycardia (n = 9), and others (n = 19).

RESULTS

Acute success at the second ablation was achieved in 79% of patients. At 20 +/- 9 months after the procedure, 69% of these patients reported having significantly fewer symptoms than before the second ablation, and 51% were free of symptoms. Only 16% were using antiarrhythmic medications. Complications included a small pericardial effusion in two patients, hypotension in one patient, and a femoral pseudoaneurysm in another.

CONCLUSIONS

Advanced mapping is a useful and safe adjunct for catheter ablation after ablation has failed in patients with complex substrate.

Predictors of Recurrence Following Catheter Ablation of Atrial Fibrillation Using an Irrigated-Tip Ablation Catheter

INTRODUCTION

The aims of this study were to identify predictors of recurrence after catheter ablation of atrial fibrillation (AF) and to report the safety and efficacy of catheter ablation of AF using an irrigated-tip ablation catheter.

METHODS AND RESULTS

Seventy-five consecutive patients (51 men [68%]; age 54 +/- 13 years) with symptomatic drug-refractory paroxysmal (42 patients), persistent (21 patients), or permanent (12 patients) AF underwent catheter ablation of AF using an irrigated-tip ablation catheter and a standard ablation strategy, which involved electrical isolation of all pulmonary veins (PVs) and creation of a cavotricuspid linear lesion. At 10.5 +/- 7.5 months of follow-up following a single (n = 75) or redo ablation procedure (n = 11), 39 (52%) of the 75 patients were free of AF, 10 were improved (13%), and 26 had experienced no benefit from the ablation procedure (35%). Seventy-six percent of patients with paroxysmal AF were free from recurrent AF. The most significant complications were two episodes of pericardial tamponade, mitral valve injury in one patient, two strokes, and complete but asymptomatic PV stenosis in one patient. Cox proportional hazards multivariate regression analysis identified the presence of persistent AF, permanent AF, and age >50 years prior to the ablation are the only independent predictors of AF recurrence after the first PV isolation procedure.

CONCLUSION

Catheter ablation of AF using a strategy involving isolation of all PVs and creation of a linear lesion in the cavotricuspid isthmus using cooled radiofrequency energy is associated with moderate efficacy and an important risk for complications. The best results of this procedure are achieved in the subset of patients who are younger than 50 years and have only paroxysmal AF.

Occurrence and management of atrial arrhythmia after long-term Fontan circulation

OBJECTIVES

In patients after the Fontan operation, we determined risk factors for late failure and for intra-atrial re-entrant tachycardia at 15 to 20 years' follow-up. Midterm results after electrophysiologic ablation therapy for these tachycardias were also evaluated.

METHODS

Current follow-up was available in 162 patients (2005 patient-years) with a wide range of underlying diagnoses operated on between February 1978 and May 1995. Risk factor analysis included patient-related and procedure-related variables, with late failure and the incidence of re-entrant tachycardia as outcome parameters.

RESULTS

Forty late failures were observed (2.0 per 100 patient-years). At 15 years, Kaplan-Meier estimated survival was significantly (P =.007) better for patients with tricuspid atresia (93%) compared with that for patients with complex congenital malformation (71%). The sole multivariable risk factor for Fontan failure was the type of underlying diagnosis. At 20 years' follow-up, overall freedom from tachycardia was estimated to be 46% +/- 12%. Acute success of electrophysiologic ablation was seen in 25 (83%) of 30 patients, and Kaplan-Meier estimated freedom from recurrent tachycardia was 81% +/- 10% at 3 years. Multivariate analysis identified duration of Fontan circulation as the sole risk factor for re-entrant tachycardias.

CONCLUSION

After the modified Fontan operation, long-term survival in patients with tricuspid atresia was significantly better compared with that in patients with complex congenital malformations. As first-choice therapy for atrial re-entrant tachycardias, we recommend electrophysiologic ablation therapy.

Complex Atrial Reentrant Circuits Evaluated by Entrainment Mapping Using a Multielectrode Basket Catheter

Atrial tachycardias after open heart surgery sometimes have complex reentrant circuits. A patient with a dual-loop atrial reentrant circuit occurring after mitral valve replacement was evaluated by entrainment mapping with a basket catheter. The position of the catheter was adjusted to obtain atrial electrograms of the anterior and posterior septal areas, the crista terminalis, the free wall, and the tricuspid annular region. Entrainment mapping identified a dual-loop reentry consisting of one circuit around the tricuspid annulus and another around the septal atriotomy scar. The reentrant circuit around the septal incision was eliminated by ablating the area between the septal incision and the inferior vena cava, and the circuit around the tricuspid annulus was terminated with an additional linear ablation between the tricuspid annulus and the inferior vena cava. Entrainment mapping using a multielectrode basket catheter is very useful for identifying complex atrial reentrant circuits.

Ablation of tachyarrhythmias in pediatric patients

PURPOSE OF REVIEW

Radiofrequency (RF) ablation treatment for tachyarrhythmias has been available only for the past 15 years. The success rates have been excellent with a very low frequency of complications. Because of this efficacy, the use of RF ablation in children has become standard of care even though long-term data are unavailable. In this review, common tachyarrhythmias and their current treatments in children will be discussed.

RECENT FINDINGS

Novel electrophysiology technologies such as electroanatomic mapping and sophisticated ablating catheters have improved success rates and decreased complications. The improvement is also due to better understanding of the mechanisms and etiologies of tachyarrhythmias. Both have positively impacted success rates and have made more complicated tachyarrhythmias treatable with ablation.

SUMMARY

The technologic advances in ablation and improved understanding of tachyarrhythmias over the past 15 years have greatly improved outcomes in ablative treatment of tachyarrhythmias in children. In most cases this method of treatment is the preferred first-line approach to symptomatic tachyarrhythmias in children.

Influence of High-Pass Filtering on Noncontact Mapping and Ablation of Atrial Tachycardias

The aim of the study was to define the impact of different high-pass filter settings (HPF) on the accuracy of mapping of ectopic atrial tachycardias (EAT) using a noncontact mapping (NCM) system. In 20 patients with 22 EAT a noncontact probe was deployed in the right (n = 19) or in the left atrium (n = 3). The device enables interpolation and analysis of unipolar electrograms. It provides information on focus localization and signal morphology. These parameters were compared in different HPF of 0.5 Hz, 2 Hz, 8 Hz, and 16 Hz. The NCM signal morphology was preserved at all HPF. An initial negative deflection recorded by NCM system showed a positive predictive value of 93% regarding the ablation success. The deviation (spatial disparity) between visualized focus origin and successful ablation site was 6.9 +/- 5.4 mm. Between two consecutive filter settings, the focus shift was more pronounced between 0.5 and 2 Hz (5.4 +/- 4.5 mm) compared to a setting between 8 and 16 Hz (2.9 +/- 2.9 mm; P < 0.05). Successful ablation was achieved in 15/18 right atrial tachycardias (83%) and in 2/3 left atrial arrhythmias. Different HPF influence NCM spatial analysis of EAT. However, a small variability in foci localization does not impact final ablation results.

Single chamber atrial fibrillation involving only the left atrium: implications for maintenance and radiofrequency ablation therapy

Due to the anatomic and the functional interatrial relationship, AF is a biatrial process. Whether one of the atria could sustain AF is not known. This study included 11 patients (mean age 57 +/- 10 years, 7 men) with AF who showed a distinct activation pattern, characterized by regular activity in the right atrium (RA) and irregular fibrillatory activity confined to the left atrium (LA) throughout the AF episodes. Each of the atria was mapped with 64-electrode basket catheters. AF was monitored for 74 +/- 26 minutes. Complex and irregular activity with a cycle length of 138 +/- 43 ms was observed in the LA throughout the monitoring time. The posterior and the roof of the LA showed the highest degree of disorganization. RA was activated by regular wavefronts with a cycle length of 194 +/- 22 ms (P < 0.001, compared with LA). No fibrillatory activity was observed in the RA. All wavefronts that activated the RA were of septal origin: high anteroseptal 52%, low posteroseptal 22%, mid-septal 18, and dual wavefronts (from the high anteroseptal and low posteroseptal pathways) 8%. The lateral wall of the RA was activated in a superoinferior direction in 82% of all activations. A left-to-right conduction block during AF and a rotor of fibrillatory activity located in the posterior wall of the LA were observed in two patients. Isolated AF in the LA showed various surface electrocardiographic patterns. It is concluded that LA alone without participation of the RA can sustain AF. These data have implications for mechanisms and the ablative therapy of AF.

Impact of atrial fibrillation on the voltage of bipolar signals acquired from the left and right atria

A detailed analysis of the impact of atrial fibrillation (AF) on the voltage of the atrial signals acquired from various right and left atrial regions has not been reported. Thirteen patients (mean age 55 +/- 11 years, range 39-67 years, 5 women) with AF were included in this study. Mapping of the left and the right atrium was performed with 64-electrode basket catheters. AF cycle lengths were calculated over 10-second time intervals using a custom-made software. Voltage of the bipolar signals during AF was calculated by measuring the amplitudes of 30 consecutive signals in the left and the right atria. During sinus rhythm voltage differences between the left (3 +/- 2.9 mV) and the right atrium (2.8 +/- 2.4 mV, P = 0.15) were insignificant. During AF, as compared to sinus rhythm, voltages of the bipolar signals were significantly reduced in the left (0.9 +/- 0.6 mV) and the right (1.3 +/- 1.1 mV) atria (P < 0.001 compared with sinus rhythm). In the left atrium, the posterior wall showed the most pronounced voltage reduction (1.1 +/- 0.8 mV vs 5.3 +/- 4.6 mV, P < 0.001). In the right atrium the septal wall showed the greatest reduction in voltage amplitude (0.8 +/- 0.6 mV vs 2.5 +/- 1.5 mV, P < 0.001). There was a close correlation between the voltage values and the AF cycle length. The smallest voltage values and greatest amplitude reductions were observed during faster and more disorganized AF activity. It is concluded that during AF, the voltage of bipolar signals is significantly reduced as compared to sinus rhythm. The reduction in voltage expresses atrial and regional disparity and correlates strongly with local AF cycle lengths and the degree of AF disorganization.

Noncontact mapping of ectopic atrial tachycardias: different characteristics of isopotential maps and unipolar electrogram

The success rate for catheter ablation of ectopic atrial tachycardia (AT) has been limited by the inherent difficulty in localizing the site of origin within the complex three-dimensional structures of the atria. The objective of the study was to determine the usefulness of a noncontact mapping system for catheter ablation of AT. Radiofrequency ablation of 25 ATs was performed using a noncontact mapping system. Three different characteristics of isopotential maps and unipolar electrogram morphologies were observed: Group 1: Isopotential maps displayed a narrow, sharp ring of colors around a white, center spot. Unipolar electrograms revealed a Q-S morphology with a rapid dV/dt. Group 2: Isopotential maps displayed a broad ring of colors with little or no white spot in the center. Unipolar electrograms revealed a low amplitude, broad and smooth Q-S morphology in front of a second component with a rapid dV/dt. Group 3: Isopotential maps displayed a broad ring of colors. Unipolar electrogams revealed a low amplitude and fractionated waveform followed by endocardial breakthrough with a gradual dV/dt. Radiofrequency catheter ablation was successful in all ATs of groups 1 and 2, and failed in two of three ATs in group 3. The overall success rate was 92%. No severe complications were observed. Noncontact isopotential mapping is helpful to identify and characterize the origin of ectopic AT. Ablation success is associated with the characteristics of isopotential maps and unipolar electrogram morphologies. The overall success rate was 92%.

Electrophysiologic characteristics of the spontaneous onset and termination of atrial fibrillation

Electrophysiologic characterization of the onset and termination of atrial fibrillation (AF) is poorly defined. Our study population consisted of 21 consecutive patients (mean age 58 +/- 9 years, 6 women) with intermittent (10 patients) or persistent (11 patients) AF. Mapping of the left atrium (LA) and the right atrium (RA) during initiation and termination of AF was performed with a 64-electrode basket catheter. A total of 92 spontaneous AF onsets (in 16 patients) and 63 spontaneous AF terminations were analyzed. Irrespective of the origin of the triggering atrial premature complex (APC), the onset of AF was preceded by an intermediary rhythm that consisted of repetitive firing from the focus that generated the initial APC, reentry around the mitral annulus, or typical atrial flutter. The earliest fibrillatory activity was constantly produced by circumvented regions (generators) localized most frequently in the posterior wall of the LA. Generators of fibrillatory activity were not observed in the RA for any of the patients. In the RA, AF is maintained by a mixture of macro-reentry and driving wave fronts of left atrial origin. Four modes of AF termination were observed: a multifocal rhythm (19 episodes, 30%), left atrial tachycardia (17 episodes, 27%), direct conversion to sinus rhythm (15 episodes, 24%), and conversion to typical atrial flutter (12 episodes, 19%). A repetitive rapid rhythm initiated most often by APCs plays a crucial role in the initiation of AF via activation of the generators of fibrillatory activity. The LA plays a central role in the initiation of AF by serving as a substrate for generators of fibrillatory activity. Termination of AF consists of a heterogenous group of unstable rhythms.

Biatrial multisite mapping of atrial premature complexes triggering onset of atrial fibrillation

Pulmonary veins are considered to be the most common origin of the focal activity that triggers the onset of atrial fibrillation (AF). However, little is known about the importance of ectopic activity located outside the pulmonary veins. This study included 45 patients (8 women and 37 men, mean age 55 +/- 12 years) with paroxysmal (n = 25) and persistent (n = 20) AF in whom multisite mapping of the right and left atria was performed using a 64-electrode basket catheter (n = 21) or a noncontact mapping system (n = 24). Spontaneous or orciprenaline-induced atrial premature complexes (APCs) were mapped. In all, 94 AF onsets from 38 distinct foci in 30 patients were observed and analyzed. Of these foci, 20 (53%) were located in pulmonary veins and 18 (47%) were located outside the pulmonary veins in other parts of the atria. In 22 patients (73%), AF was reproducibly induced by APCs from a single focus (59 episodes). In 8 patients (27%), AF originated from 2 distinct foci (35 episodes). Additionally, 20 of 30 patients (67%) who developed AF had APCs in different locations not inducing AF. APCs inducing AF had shorter coupling intervals than APCs not inducing AF (307 +/- 54 vs 409 +/- 76 ms, p <0.001). This study showed that 47% of ectopic foci triggering the onset of AF were located outside the pulmonary veins in extravenous parts of the left atrium and the right atrium, and 27% of patients had AF onsets of bifocal origin. These data challenge the current opinion that extrapulmonary foci play a minor role in inducing AF.

Atrial components contributing to pseudo r' deflection in lead V1 in slow/fast atrioventricular nodal reentrant tachycardia: analysis of the atrial activation sequence by basket catheter isochronal mapping

Electrocardiographic recognition of the P' wave during tachycardia is very useful in the diagnosis of supraventricular tachycardias. In slow/fast (S/F) atrioventricular nodal reentrant tachycardia (AVNRT), no discrete P' waves are observed on ECG and pseudo r' deflection in lead V1 (pseudo r') is commonly recognized. However, the atrial components that contribute to the genesis of pseudo r' in lead V1 have not been described and this study aimed to clarify them by analysis of the whole activation sequence of the right atrium using Basket catheter isochronal mapping. The study group comprised 48 patients with AVNRT. Pseudo r' was defined as an upward deflection in the terminal portion of the QRS complex during tachycardia that was not recognized during sinus rhythm and it occurred in 45 patients (94%). During S/F AVNRT, the retrograde atrial activation was earliest on His bundle electrogram, followed by the coronary sinus ostium, distal coronary sinus and high right atrium. Only the high lateral aspect of the right atrium was activated after the end of the QRS complex. The interval between the onset of QRS in multiple surface ECG leads and the atrial activities on high right atrium was similar to the V-r' interval in lead V1 (111+/-20ms, 117+/-11 ms) and correlated with the V-r' interval (r=0.56). Pseudo r' deflection in lead V1 is a highly sensitive indicator of S/F AVNRT, and appears to result from the activation of the superolateral aspect of the right atrium.

Radiofrequency catheter ablation for intra-atrial reentrant tachycardia after surgery of atrial septal defect: use of isopotential mapping (QMS system) to demonstrate bidirectional complete block

A 51 year-old Japanese man who had undergone surgical correction of an atrial septal defect at the age of 18 years old was referred to our institute for evaluation of his atrial arrhythmia. The conventional electrophysiological study was combined with a new technique utilizing an isopotential and isochronal mapping system (QMS) to visualize the electrical signals recorded with a 64-electrode basket catheter. Using this system, an intra-atrial reentrant tachycardia (IART) was demonstrated. The isopotential map recorded with the QMS (QMS-isoP) rapidly revealed a clockwise global reentrant circuit in the mid free wall of the right atrium and a narrowest activation isthmus between the lower end of the atriotomy scar and the inferior vena cava (IVC). After confirming entrainment with concealed fusion at the lower end of the atriotomy scar, radiofrequency energy was delivered linearly from this site to the IVC by slowly dragging the catheter. The elimination of the IART was defined by the QMS-isoP which demonstrated bidirectional block during pacing from both sides of the ablated linear lesion. The conventional technique of entrainment with concealed fusion combined with the QMS-isoP may result in a highly sophisticated method for identifying global reentrant circuits and for defining bidirectional block after eliminating the IART.

Role of contact and noncontact mapping in the curative ablation of tachyarrhythmias

Assessment of the timing of electrical activation recorded by multiple electrodes positioned in various locations within the heart has been the conventional method for mapping cardiac arrhythmias. This technique requires fluoroscopy for catheter manipulation, which in addition to being harmful (ionizing radiation), is inadequate for visualizing the complex three-dimensional cardiac anatomy and lacks reproducibility regarding localization of sites of interest. Because of these limitations, several new mapping systems that can function in a complimentary role to the conventional mapping technique, or can be used independently, have been developed. These new mapping strategies have unique advantages. They overcome the limitations of fluoroscopy by creating accurate three-dimensional intracardiac maps. The ability to localize and accurately display intracardiac catheter positioning and ablation lesion sites facilitate increasingly complex catheter ablation procedures.

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium

OBJECTIVES

The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA).

BACKGROUND

Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood.

METHODS

A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system.

RESULTS

Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71).

CONCLUSIONS

Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.

Electrical conduits within the inferior atrial region exhibit preferential roles in interatrial activation

Differences between conduction properties of interatrial conduits and their roles in initiation and maintenance of supraventricular arrhythmias remain unclear. Our objective was to determine details of interatrial activation in inferior atrial region and to correlate intra-atrial and interatrial activation patterns with the site of origin of atrial ectopic activation. In 9 dogs, basket-catheters carrying 64 electrodes were deployed into both the right atrium (RA) and left atrium (LA). A 10-electrode catheter was inserted into the coronary sinus (CS). Activation patterns of the RA, LA, and CS were compared during pacing in the CS, in RA inferoparaseptum posterior to Eustachian ridge-tendon of Todaro (TT), and in inferior RA near the CS ostium (anterior to TT). We found that pacing in proximal and middle CS resulted in a RA breakthrough invariably at the CS ostium, consistent with conduction through a CS-RA connection. Meanwhile, LA breakthrough emerged in inferoposterior region (inferior to mitral annulus), suggesting conduction through a CS-LA connection. While pacing in distal CS, LA breakthrough shifted to middle posterolateral wall. Whereas, the RA was activated by the LA directly through the septum. During pacing in RA inferoparaseptum posterior to TT, the LA was activated directly through the septum at 22 +/- 4 ms. Whereas, during pacing anterior to TT, the LA was activated through both the CS and the septum while earliest activation was delayed by 38 +/- 5 ms. In conclusion, both the interatrial septum and CS musculature form electrical conduits in inferior atrial region in canine. Differences in activation properties between the conduits in inferior interatrial region result in selective interatrial activation patterns during ectopic activation.

Diagnosis and ablation of atrial flutter using a high resolution, noncontact mapping system

The ablation of atrial flutter can sometimes be time consuming and unsuccessful using conventional catheter techniques especially in patients with recurrences after previous ablation procedures. Simultaneous high resolution mapping from multiple sites may overcome some of the limitations. Therefore, a new high resolution noncontact mapping system was used for diagnosis and ablation of atrial flutter in 15 patients. The mapping system consists of a catheter-mounted multielectrode array, an amplifier, and a computer workstation. Far-field potentials recorded by the multielectrode catheter are amplified, digitized, and sampled at 1.2 kHz, and digitally filtered to construct high resolution activation maps during tachycardia. Ablation catheters can be steered to target sites without fluoroscopy. In 12 of the 15 patients the analysis of the activation sequence during tachycardia showed a counter-clockwise, and in 1 of 15 patients a clockwise, rotating wavefront using the isthmus as part of the reentrant circuit. In two patients no tachycardia could be induced. In 3 of the 15 patients with previous conventional ablation procedures the gap in the line of block in the isthmus region was identified and marked on the animation model. The isthmus in the right atrium was ablated and isthmus block verified by the mapping system in all patients. No complications were observed. No recurrences of atrial flutter occurred during follow-up of 4 +/- 1.7 months. The total procedure and fluoroscopy time was 171 +/- 50.0 minutes and 24 +/- 12.7 minutes, respectively. In conclusion, the use of the new high resolution noncontact mapping system in patients with right atrial flutter is safe and highly effective. In patients with previously failed conventional ablation procedures the use of a noncontact mapping system may facilitate the identification of the gap in the line of block in the isthmus region and reablation of atrial flutter.

Elimination of focal atrial fibrillation with a single radiofrequency ablation: use of a basket catheter in a pulmonary vein for computerized activation sequence mapping

A focal source for atrial fibrillation (AF) may be found in the first few centimeters of the pulmonary veins. Radiofrequency (RF) ablation may be directed at this source using activation mapping, but if the responsible atrial extrasystoles are infrequent or difficult to map, elimination of the source may require complete electrical isolation of the vein with multiple RF lesions. A new three-dimensional mapping system using a 64-pole basket catheter has been developed recently. We report the use of this system for ablation of focal AF in two patients. Mapping identified foci in the left and right superior pulmonary veins. Each focus was eliminated with a single RF ablation.

Basket catheter-guided three-dimensional activation patterns construction and ablation of common type atrial flutter

Construction of three-dimensional activation maps and evaluation of ablation-created bidirectional block in the tricuspid valve-inferior vena caval (TV-IVC) isthmus in patients with atrial flutter (AF) are difficult with conventional mapping technique. In 36 patients with type I AF (25 men, 11 women; mean age 62 +/- 10.5 years) a multielectrode basket catheter (BC) was deployed in the right atrium (RA). Out of 64 BC electrodes, 56 bipolar electrograms were derived. Three-dimensional activation patterns were constructed with a software program. Stable electrograms of satisfactory quality were obtained in 49 +/- 2 electrode pairs. Capture was possible in 36 +/- 3 of bipoles. In counterclockwise AF (CCW-AF) and clockwise AF (CW-AF) episodes, cycle lengths and TV-IVC isthmus conduction times were 248 +/- 26 ms and 251 +/- 23 ms, (P = 0.74) and 105 +/- 28 ms and 106 +/- 33 ms (P = 0.92), respectively. Conduction velocity in the TV-IVC isthmus was lower than in the anterior or septal limbs of the circuit, in counterclockwise or clockwise episodes. Double potentials were recorded in 94% of patients. Three-dimensional activation patterns were delineated and displayed as isochronal maps. The reentry circuit involved the TV-IVC isthmus, septal, and anterior walls and a part of the RA roof anterior to superior vena cava. Postablation isthmus conduction was evaluated through the sequence criteria, local electrogram-based criteria, and the analysis of three-dimensional activation patterns of the paced rhythms. The complete isthmus block was associated with a significant increase of the low anterior low septal conduction interval (152 +/- 29 vs 104 +/- 32 ms, P = 0.001) and the low septal-low anterior conduction interval (150 +/- 31 vs 107 +/- 33 ms, P = 0.001). Radiofrequency ablation was successful in 32 (90%) of 36 patients. In conclusion, the current mapping system enables construction of three-dimensional activation patterns and facilitates evaluation of the postablation TV-IVC isthmus block in patients with AF.

Computer-assisted animation of atrial tachyarrhythmias recorded with a 64-electrode basket catheter

OBJECTIVES

The aim of this study was to assess the value of a new mapping technique based on computer-assisted animation of multielectrode basket catheter (BC) recordings in patients with atrial arrhythmias.

BACKGROUND

The three-dimensional activation patterns of cardiac arrhythmias are not completely understood owing to limitations of conventional mapping techniques.

METHODS

The study included 32 patients with atrial tachycardia (AT) and 38 patients with atrial flutter (AFL). A software program was developed to analyze the activation patterns based on 56 bipolar electrograms recorded with a 64-electrode BC deployed in the right atrium (RA).

RESULTS

The total time needed for the animation of activation patterns of atrial arrhythmias was 5 +/- 0.8 min. In 22 patients with right AT, the animated maps revealed that arrhythmia was unifocal in 15 patients, multifocal in 2 patients, polymorphic in 4 patients and reentrant in 1 patient. In 10 patients with left AT, breakthroughs on the right side of the septum (2 in 8 patients and 1 in 2 patients) and a left-to-right activation of the RA were demonstrated. In patients with typical AF, the reentrant excitation was a broad activation front with preferential propagation around the tricuspid annulus. In patients with atypical AFL, the reentry circuit involved one of the venae cavae and a line of block located in the posterior wall.

CONCLUSIONS

The computer-assisted animation of multiple electrograms recorded with a BC is a valuable mapping tool that delineates the three-dimensional activation patterns of various atrial arrhythmias. The technique is appropriate for complex, short-lived or unstable arrhythmias.