CARTO Mapping System Research Articles

Regional heterogeneity of right atrial repolarization. Monophasic action potential mapping in swine

Objectives. To establish a set of reference values for regional dispersion of repolarization of the right atrium in the in situ heart of pigs and to see if the global dispersion of repolarization could be estimated from regional mapping. Design. Monophasic action potential (MAP) were sequentially recorded from 28 ± 3 sites in seven different regional areas of the right atrium: lateral, anterior and posterior wall, septum, sinoatrial node (SAN), appendage, and near the tricuspid annulus (TA) in 10 healthy pigs using the CARTO mapping system. Results. The activation time (AT), MAP duration (MAPd) and end of repolarization time (EOR) of the whole right atrium were 68 ± 7, 239 ± 20 and 270 ± 23 ms, respectively. There were no significant differences on MAPd and EOR among the seven regional areas, nor between each of the regional and global values. The global dispersions of the MAPd and EOR were 75 ± 19 and 103 ± 13 ms, which were significantly greater than those obtained from any of the seven regional areas and those between two remote regions, SAN vs. TA and SAN vs. appendage regions. Conclusions. The data of regional and global dispersion of repolarization in healthy pigs can serve as reference values for evaluation of increased dispersion of repolarization. The global dispersions of MAPd and EOR in the right atrium were poorly estimated from regional mapping, suggesting the importance of global mapping in evaluating the dispersion of atrial repolarization.

Ventricular repolarization sequences on the epicardium and endocardium. Monophasic action potential mapping in healthy pigs

To investigate repolarization sequence, monophasic action potentials were recorded from a mean of 153 ± 54 left and right ventricular epicardial and endocardial sites in 10 pigs using the CARTO mapping system (Biosense Webster, Waterloo, Belgium). The activation time and end-of-repolarization (EOR) time were measured and 3-dimensional maps of activation and repolarization sequences constructed. Results In 8 of 9 pigs, both the activation and EOR times appeared first in the septum and last in the latero-basal areas on the endocardium, not on the epicardium. The EOR followed the activation sequence, both on the epicardium (in 8/9 pigs) and endocardium (in 8/8 pigs). The maximal EOR differences were 84 ± 20 ms, whereas the local EOR differences between paired sites against each other on the left ventricular epicardium and endocardium were 11 ± 9 ms in the apex and 12 ± 12 ms in the anterior wall. Conclusion The EOR follows the activation sequence both on the epicardium and endocardium. The apico-basal gradients are predominant repolarization gradients, as compared with the epicardial–endocardial gradients.

Catheter Ablation for Paroxysmal Atrial Fibrillation: A Randomized Comparison between Multielectrode Catheter and Point-by-Point Ablation

Catheter ablation for paroxysmal atrial fibrillation is widely used for patients with drug-refractory paroxysms of arrhythmia. Recently, novel technologies have been introduced to the market that aim to simplify and shorten the procedure. To compare the clinical outcome of pulmonary vein (PV) isolation using a multipolar circular ablation catheter (PVAC group), with point-by-point PV isolation using an irrigated-tip ablation catheter and the CARTO mapping system (CARTO group; CARTO, Biosense Webster, Diamond Bar, CA, USA). Patients with documented PAF were randomized to undergo PV isolation using PVAC or CARTO. Atrial fibrillation (AF) recurrences were documented by serial 7-day Holter monitoring. One hundred and two patients (mean age 58 ± 11 years, 68 men) were included in the study. The patients had comparable baseline clinical characteristics, including left atrial dimensions and left ventricular ejection fraction, in both study arms (PVAC: n = 51 and CARTO: n = 51). Total procedural and fluoroscopic times were significantly shorter in the PVAC group (107 ± 31 minutes vs 208 ± 46 minutes, P < 0.0001 and 16 ± 5 minutes vs 28 ± 8 minutes, P < 0.0001, respectively). The AF recurrence was documented in 23% and 29% of patients in the PVAC and CARTO groups, respectively (P = 0.8), during the mean follow-up of 200 ± 13 days. No serious complications were noted in both study groups. Clinical success rates of PV isolation are similar when using multipolar circular PV ablation catheter and point-by-point ablation with a three-dimensional (3D) navigation system in patients with PAF, and results in shorter procedural and fluoroscopic times with a comparable safety profile.

Comparison of computed tomography imaging with intraprocedural contrast esophagram: Implications for catheter ablation of atrial fibrillation

Computed tomography (CT) has been used to localize the esophagus before radiofrequency ablation (RFA) of atrial fibrillation (AF). The purpose of this study was to compare esophageal imaging by CT versus esophagram. CT imaging of the left atrium was performed in 57 patients 1 week before RFA and was imported into the CARTO mapping system. The electrophysiologist created a virtual shell of the left atrium and pulmonary veins (PVs) that was merged with the CT image; however, the CT-defined location of the esophagus was not displayed. The patient was then given 10 mL of oral contrast. Using fluoroscopy, an electroanatomic catheter tagged the esophageal borders outlined by esophagram. The CT-defined esophagus was then imported, and the borders were tagged on the merged map. In this manner, the esophagus borders by esophagram versus those by CT were compared. The maximum diameter of the esophagus by esophagram versus CT was not different (16.3 +/- 3.4 vs. 16.5 +/- 3.1 mm; P = .7). The esophagus was near the left PVs in 34 (62%), center in 13 (24%), and near the right PVs in eight (15%) patients. There was concordance between CT and esophagram in 48 of 55 patients (87%; P = .2). Ye, in 21 (44%) of 48 patients with concordant location, the CT-defined esophageal borders were separated from the esophagram-defined borders by >or=50% of the esophagus diameter. Reliance on remotely acquired CT images does not ensure adequate intraprocedural localization of the esophagus or enhance recognition of esophageal motility.

Catheter-ablation of ventricular tachycardia in patients with coronary artery disease: influence of the endocardial substrate size on clinical outcome

Ablation of symptomatic ventricular tachycardia (VT) in patients with coronary artery disease is frequently performed using the three dimensional mapping system CARTO. In the amplitude map, bipolar potentials of <1.5 mV are considered abnormal and represent damaged myocardium due to previous infarction. This pathological electrical area can be arrhythmogenic, serving as the substrate for reentrant VT. The purpose of this study was to correlate the size of the endocardial substrate with the success of VT catheter ablation. Included in this retrospective analysis were 69 consecutive patients with coronary artery disease who underwent ablation for symptomatic clinical VT using CARTO. The voltage maps were analyzed and the area with abnormal bipolar electrograms (<1.5 mV) was determined using geometric approximation models. The area of abnormal electrograms was divided into three sizes: small (<or=15 cm(2); 11 patients), medium (16-99 cm(2); 50 patients), and large (>or=100 cm(2); 8 patients). Patient characteristics were not different between the three substrate groups in regard to age, tachycardia cycle length, or number of radiofrequency applications, however differed significantly between the small, medium and large group in regard to left ventricular ejection fraction (44 +/- 12% vs. 32 +/- 9% vs. 21 +/- 7%, respectively; P = 0.001). Overall, there was a significant correlation between myocardial infarction locations and endocardial substrate sizes (P = 0.031), such that 73% of small substrates were found after inferior myocardial infarctions, and 100% of large substrates after anterior and multiple myocardial infarctions (P = 0.003). After ablation, inducibility of ventricular arrhythmias was more rare in patients with small substrates compared to patients with medium or large substrates (small substrates: 9%, medium and large substrates: 43%, P = 0.043). Although during follow-up of 25 +/- 17 months (1 day to 72 months) there was no significant difference between endocardial substrate sizes in regard to recurrence rates (small: 27%, medium: 38%, large: 50%, P = 0.588), patients with a small substrate did not have fast VT or ventricular fibrillation (VF), in contrast to 30% and 38% of patients with medium and large substrates, respectively. We conclude that in patients with coronary artery disease a small area of low amplitude bipolar potentials (<or=15 cm(2)) was seen more often after inferior myocardial infarction than after anterior and multiple infarctions. After ablation, patients with small substrates were rarely inducible and showed a more benign course during follow-up (trend towards fewer arrhythmia recurrences and no fast VT or VF). As a result smaller arrhythmogenic substrates appear to be better amenable to catheter ablation than larger substrates.

Image fusion shows the role of incomplete ablation lines in creating a substrate for left atrial flutter occurring after atrial fibrillation ablation

a r t ( A 56-year-old man with permanent atrial fibrillation AF) underwent circumferential pulmonary vein (PV) ablaion plus additional ablation of atrial areas having fractionted electrograms. An electroanatomic mapping system CARTO, Biosense-Webster, Diamond Bar, CA, USA) was sed during the procedure. Computed tomographic (CT) maging of the left atrium (LA) performed 2 days before the blation procedure showed a common trunk of the left PVs. ractionated electrograms were concentrated mainly in the osterior portion of the left PV common trunk ostium. Three onths later, the patient underwent a second electrophysilogic study for palpitation recurrence, with ECG demontration of atypical atrial flutter. Biatrial electroanatomic apping and entrainment pacing during the procedure howed the LA origin of the flutter, which was sustained by

Atrioventricular node reentrant tachycardia ablation in a patient with congenitally corrected transposition of the great vessels using the CARTO mapping system

We present a case of a 21-year-old female with congenitally corrected transposition of the great vessels and episodes of supraventricular tachycardia. We performed an electrophysiological study and successful ablation using an electro-anatomical mapping system. A single His bundle appeared to be located at the apex of the triangle of Koch and at electrophysiological study there was evidence of triple antegrade AV nodal pathways--slow, intermediate and fast, with two types of AV nodal re-entrant tachycardias. A series of radiofrequency ablations in the right posteroseptal area eliminated both slow and intermediate pathway conduction and cured the tachycardias.

Anatomical and electrophysiological approach to atrial fibrillation ablation: technical limitations

Pulmonary vein (PV) disconnection by radiofrequency (RF) catheter ablation has been reported to cure atrial fibrillation (AF). Different techniques have been proposed. The aim of this study was to evaluate the technical limitations of both anatomical and electrophysiological approaches. A total of 110 PVs were ablated in 26 consecutive patients (23 male, 3 female, mean age 51 +/- 9.5 years) with paroxysmal (n = 19, 73%), persistent (n = 3, 12%) or permanent (n = 4, 15%) AF. Accurate reconstructions of the PV ostia were obtained using fluoroscopy, electrophysiology, and the CARTO mapping system. Electrophysiological mapping was attempted in all PVs by means of a decapolar circular catheter. RF ablation was performed in a single-blind fashion in order to anatomically create circumferential lines around each PV. Completeness of anatomically-guided, circumferential RF lesions around the PVs was established by the physician using the CARTO system, who was unaware of the decapolar circular catheter electrophysiological recordings of the PVs. If PV potentials persisted, RF delivery was targeted to the electrophysiological breakthroughs. All PV ostia were anatomically ablated by performing circumferential RF lesions. Among 110 PVs, 73 (66%) were fully mapped by use of circular catheters. After anatomical ablation, electrical disconnection was achieved in 44/73 PVs (60%). In the remaining 29 PVs (40%), a median of one RF pulse (mean 1.8 +/- 1.4) was necessary to achieve complete PV disconnection. Total procedure duration, fluoroscopy time, and RF delivery time were 232 +/- 29, 50 +/- 16 and 39 +/- 11 min, respectively. Pericardial effusion occurred in one patient after the procedure. After 10.5 +/- 6.4 months, 21 patients (81%) were in stable sinus rhythm and 13 of them (62%) discontinued all drugs after 6 months. Only 4 patients (15%) required two procedures. Electrical PV disconnection cannot be achieved in many PVs by means of a pure anatomical approach. On the other hand, electrophysiological mapping cannot be performed in many PVs owing to anatomical variations. An integrated approach might overcome these limitations.

Tpeak-Tend Interval as an Index of Global Dispersion of Ventricular Repolarization: Evaluations Using Monophasic Action Potential Mapping of the Epi- and Endocardium in Swine

The ECG interval from the peak to the end of the T wave (Tpeak-Tend) has been used as an index of transmural dispersion of ventricular repolarization (DVR). The correlation between the Tpeak-Tend interval and the global DVR, however, has not been well-evaluated. Monophasic action potentials (MAPs) were recorded from 51+/-10 epicardial and 64 +/- 9 endocardial sites in the left ventricles of 10 pigs, and from 41+/-4 epicardial and 53+/-2 endocardial sites in the right ventricles of 2 of the 10 pigs using the CARTO mapping system. The end of repolarization times over the epi- and endocardium were measured, and the end of repolarization dispersions over the epicardium (DVR-epi), over the endocardium (DVR-endo) and over both (DVR-total) were calculated. The QTpeak, QTend and Tpeak-Tend intervals as well as the QTpeak and QTend dispersions were obtained from the simultaneously recorded 12-lead ECG. The maximal Tpeak-Tend intervals (57+/-7 ms) were consistent with the DVR-total (58+/-11 ms, p>0.05), and significantly correlated with the DVR-total (r=0.64, p<0.05). However, the mean Tpeak-Tend intervals (44+/-5 ms), and Tpeak-Tend intervals from lead II (41+/-6 ms) and V5 (43+/-5 ms) were all significantly smaller than and poorly correlated with the DVR-total, as were the QTpeak and QTend dispersions (15+/-2 ms vs. 21+/-4 ms). The maximal Tpeak-Tend interval may be used as a noninvasive estimate for the global DVR, but not the QTpeak and QTend dispersions, nor the mean Tpeak-Tend interval and that from a single lead.

In vivo validation of the coincidence of the peak and end of the T wave with full repolarization of the epicardium and endocardium in swine

Previous in vitro studies have suggested full repolarization of the epicardium coincides with the peak of the T wave (T(peak)) and that of the M cells coincides with the end of the T wave (T(end)). However, in vivo validation of the theory is lacking. Monophasic action potentials (MAPs) were recorded using the CARTO mapping system from 51 +/- 10 epicardial sites and 64 +/- 9 endocardial sites of the left ventricle in 10 pigs and from 41 +/- 4 epicardial sites and 53 +/- 2 endocardial sites of the right ventricle in two of the 10 pigs. End of repolarization (EOR) times over the epicardium (EOR(epi)), endocardium (EOR(endo)), and over both (EOR(total)) were obtained. QT(peak) and QT(end) intervals were measured from simultaneously recorded 12-lead ECG. Minimal and maximal EOR(total) were observed in the left ventricle in all pigs. Minimal EOR(total) was on the epicardium in five pigs, and maximal EOR(total) was on the endocardium in nine pigs. Minimal, mean, and maximal QT(peak) intervals all were significantly smaller than maximal EOR(epi) (322 +/- 23 ms, P <.01). No significant difference was found between maximal QT(end) interval (338 +/- 30 ms) and maximal EOR(endo) (339 +/- 24 ms, difference = 1 +/- 19 ms, P =.92), between maximal QT(end) interval and maximal EOR(total) (341 +/- 24 ms, difference = 2 +/- 18 ms, P =.69), or between minimal QT(peak) interval (283 +/- 28 ms) and minimal EOR(total) (282 +/- 20 ms, difference = 0 +/- 15 ms, P =.95). In in vivo pig models, T(peak) does not coincide with full repolarization of the epicardium but coincides well with the earliest EOR, whereas the T(end) corresponds with the latest EOR. These findings suggest that not only the transmural gradients but also the apicobasal repolarization gradients contribute to genesis of the T wave.

QT dispersion failed to estimate the global dispersion of ventricular repolarization measured using monophasic action potential mapping technique in swine and patients

The aim of this study was to evaluate whether the QT dispersion measured from 12-lead electrocardiogram (ECG) can estimate the global dispersion of ventricular repolarization (DVR) measured using a monophasic action potential (MAP) mapping technique. Monophasic action potentials were recorded from 75 ± 12 left ventricular sites in 10 pigs and from 48 ± 16 left or right ventricular sites in 15 patients using the CARTO mapping system. The maximum DVRs in both end-of-repolarization and MAP duration among all the mapped sites were calculated and termed as global DVR for each measurement. QT intervals, QT peak and QT end, were measured from the 12-lead ECG, and QT dispersions; namely the differences between the maximum and the minimum of the QT peak and QT end were calculated. We found that QT dispersions were significantly smaller than ( P < .05) and poorly correlated with the global DVRs both in pigs and patients. Bland-Altman agreement analysis demonstrated a marked variation of the differences and an obvious lack of agreement between the results obtained using the ECG and the MAP methods. In our patients, the global DVR increased markedly during ventricular tachycardia as compared with that during sinus rhythm ( P < .05), whereas there was no significant difference in QT dispersion between these 2 subgroups. In conclusion, QT dispersion on the surface ECG could not estimate the global DVR measured using the MAP mapping technique. These findings are not consistent with some previously reported observations, suggesting the need for reappraisal of the electrophysiological implications of QT dispersion.

Electroanatomical Mapping and Radiofrequency Catheter Ablation of Atrial Tachycardia Originating from the Recipient Heart with Recipient-to-Donor Atrio-Atrial Conduction After Orthotopic Heart Transplantation

Atrial tachycardias resulting from recipient-to-donor atrio-atrial conduction after orthotopic heart transplantation are difficult to treat. We present two patients in whom atrial tachycardia originating in the recipient heart were successfully treated by radiofrequency ablation guided by electroanatomical CARTO mapping system. These cases illustrate that such atrial tachycardia are curable by radiofrequency ablation. Electroanatomical CARTO mapping is useful in identifying the site of origin of the tachycardia and the atrio-atrial conduction sites.

Ventricular Mapping During Atrial and Right Ventricular Pacing: Relation of Electrogram Parameters to Ventricular Tachycardia Reentry Circuits After Myocardial Infarction

Ventricular tachycardia (VT) late after myocardial infarction is usually due to reentry in the border zone of the infarct area. Identification of critical parts of the VT reentry circuit by catheter mapping without needing to induce VT is a desirable goal for VT ablation. The aim of this study was to develop a model to predict reentry circuit locations based on characteristics of sinus or paced electrograms and pace mapping (PM) recorded from the infarct region. Left ventricular electroanatomic mapping with the CARTO mapping system was performed in 16 male patients with recurrent VT late after myocardial infarction. A total of 1072 left ventricular sites were recorded during atrial pacing (AP) and right ventricular pacing (RVP), and the corresponding electrograms were analyzed for their local activation time (LAT), onset (ONS), end (END), duration (DUR), and amplitude (AMP) in each pacing sequence. At 1041 of these sites, PM was performed; the resulting stimulus to QRS intervals (S-QRS) was determined at 931 sites, the remaining 110 sites did not capture. All the obtained parameters were compared with the location of 18 ablation target areas with a radius of 2 cm defined by success of radiofrequency (RF) ablation or entrainment during VT, or both. Of 1072 sites, 227 (21%) were in the target and 845 (79%) were outside the target. All parameters were significantly different (p < 0.05) in AP and in RVP between inside and outside the target in a univariate analysis. In a multivariate analysis LAT, END, DUR, and AMP in AP, END and AMP in RVP, and S-QRS were independent predictors for the target (p < 0.05). A combination of selected parameters of these predictors (DUR in AP, AMP in RVP, and S-QRS) had a specificity of 64% with a sensitivity of 80% for the target. The observations suggest that ablation guided by a combination of abnormal electrograms in different rhythms can be useful to ablate VT and reduce the necessity of VT induction. Anatomically fixed regions of block may be important for reentry and be identifiable during sinus rhythm.

Catheter-induced linear lesions in theleft atrium in patients with atrial fibrillation: An electroanatomic study

ObjectivesIn this study using radiofrequency current and the electroanatomic mapping system CARTO, four line designs were tested in 84 patients suffering from drug-refractory atrial fibrillation (AFib). BackgroundPrevention of AFib by trigger elimination within the pulmonary veins (PVs) has been recently reported, but the success may be lesser in patients with chronic AFib or large atria requiring linear lesion deployment. MethodsType A encircled the ostia of all four PVs with a connection to the mitral annulus (MA). In type B, three lines connected anatomic barriers. Type C encircled both septal and lateral PVs with connections between PVs and to the MA. Type D encircled PVs only. In the initial 12 patients (type D/1), line validation was performed without, and in 23 patients (type D/2) with, an additional catheter inside the encircled PVs. ResultsThe ability to achieve completeness of all intended lines was 5% in type A, 21% in type B, 29% in C, 66% in type D/1, and 61% in type D/2. This resulted in stable sinus rhythm in 19% (4/21 patients) in type A, 32% (6/19 patients) in type B, 50% (7/14 patients) in type C, 58% (7/12 patients) in type D/1, and 65% (15/23 patients) in type D/2, respectively, over a mean follow-up of 620 ± 376 days. Besides thromboembolic events (one stroke and one transient ischemic attack), total occlusion of a PV was a major complication in one patient, and acute tamponade in two patients. ConclusionsComplete lesions in the left atrium were difficult to achieve using conventional radiofrequency current technology, but were associated with sinus rhythm in 74% of patients during long-term follow-up, whereas incomplete lesions led mostly to recurrences of AFib or gap-related atrial tachycardia.

Clinical experience with electroanatomic mapping of ectopic atrial tachycardia.

The aim of this study was to evaluate the clinical use of a new three-dimensional mapping system as a guide for catheter ablation of ectopic atrial tachycardia. A series of 42 consecutive patients with drug refractory ectopic atrial tachycardia was studied in a prospective observational trial with the electroanatomic mapping system CARTO. The arrhythmogenic focus was found in the right atrium in 30 patients and in the left atrium in 12 patients. The construction of a complete electroanatomic map of the right or left atrium was possible in 37 of 42 consecutive patients with ectopic atrial tachycardia. Mean activation time of the right atrium, including the proximal coronary sinus, was 94 +/- 25 ms for right atrial tachycardias; left atrial activation time during left atrial tachycardias was 86 +/- 17 ms. Average mapping time was 30 minutes for right atrial tachycardias and 22 minutes for left atrial tachycardias, allowing the collection of 86 +/- 50 and 65 +/- 28 catheter positions, respectively. The size of the area of earliest atrial activation calculated from the electroanatomic map amounted to 0.6 +/- 0.4 cm2 in right atrial tachycardias and 1.0 +/- 0.9 cm2 in left atrial tachycardias. In the right atrium the most common locations of the 33 arrhythmogenic foci in 30 patients were the high or mid-lateral right atrium (n = 10) and the inferoparaseptal region near the coronary sinus ostium (n = 7). Ectopic left atrial foci were most commonly located in an inferior position near the mitral annulus (n = 5) and in proximity to the ostium of the pulmonary veins (n = 4). Biatrial electroanatomic mapping allowed visualization of earliest right atrial activation during left atrial tachycardia at the high interatrial septum or near the coronary sinus ostium. Catheter ablation was successful in 85% of right atrial tachycardias and 82% of left atrial tachycardias. In patients with ectopic atrial tachycardia electroanatomic mapping is a safe and feasible technique that allows three-dimensional visualization of the automatic focus in a precise anatomic reconstruction of the atria. This novel mapping technology facilitates catheter ablation of complex ectopic atrial tachycardia.

Electroanatomical mapping for visualization of atrial activation in patients with incisional atrial tachycardias.

Incisional atrial tachycardias in patients following surgery for congenital heart disease are based on complex structural abnormalities in these hearts. The aim of this study was to evaluate the use of the electroanatomical mapping system, CARTO, in consecutive patients with different forms of incisional atrial tachycardia. The electroanatomical mapping system combines electrophysiological and spatial information and allows visualization of atrial activation in a three-dimensional anatomical reconstruction of the atria. Electroanatomical mapping of right atrial activation was performed in 10 patients after surgery for congenital heart disease, surgery for Wolff-Parkinson-White syndrome, or heart transplantation presenting with 13 incisional atrial tachycardias. The three-dimensional mapping allowed a rapid distinction between focal (n=3) and reentrant mechanisms (n=10) and visualization of the activation wavefronts along anatomical and surgically created barriers. Electroanatomical activation maps (mean right atrial activation time 213+/-107 ms) were constructed with 89+/-60 catheter positions during an average mapping time of 48+/-33 min. Reentrant tachycardias propagating through the tricuspid annulus-vena cava inferior isthmus (n=6) or along periatriotomy loops (n=4) were identified in eight patients. Ectopic atrial foci near surgical scars could be localized in three patients. Catheter ablation by creation of a lesion in a critical isthmus of conduction or by targeting the arrhythmogenic focus eliminated 11 of 13 incisional atrial tachycardias. Visualization of atrial activation in a three-dimensional reconstruction of the right atrium using the electroanatomical mapping system CARTO facilitates understanding of the mechanism and defines the reentrant circuits of incisional atrial tachycardias. This new method may improve the success rate of electrophysiologically guided and anatomically guided catheter ablation of incisional atrial tachycardias.

Magnetic electroanatomical mapping for ablation of focal atrial tachycardias.

Uniform success for ablation of focal atrial tachycardias has been difficult to achieve using standard catheter mapping and ablation techniques. In addition, our understanding of the complex relationship between atrial anatomy, electrophysiology, and surface ECG P wave morphology remains primitive. The magnetic electroanatomical mapping and display system (CARTO) offers an on-line display of electrical activation and/or signal amplitude related to the anatomical location of the recorded sites in the mapped chamber. A window of electrical interest is established based on signals timed from an electrical reference that usually represents a fixed electrogram recording from the coronary sinus or the atrial appendage. This window of electrical interest is established to include atrial activation prior to the onset of the P wave activity associated with the site of origin of a focal atrial tachycardia. Anatomical and electrical landmarks are defined with limited fluoroscopic imaging support and more detailed global chamber and more focal atrial mapping can be performed with minimal fluoroscopic guidance. A three-dimensional color map representing atrial activation or voltage amplitude at the magnetically defined anatomical sites is displayed with on-line data acquisition. This display can be manipulated to facilitate viewing from any angle. Altering the zoom control, triangle fill threshold, clipping plane, or color range can all enhance the display of a more focal area of interest. We documented the feasibility of using this single mapping catheter technique for localizing and ablating focal atrial tachycardias. In a consecutive series of 8 patients with 9 focal atrial tachycardias, the use of the single catheter CARTO mapping system was associated with ablation success in all but one patient who had a left atrial tachycardia localized to the medial aspect of the orifice of the left atrial appendage. Only low power energy delivery was used in this patient because of the unavailability of temperature monitoring in the early version of the Navistar catheter, the location of the arrhythmia, and the history of arrhythmia control with flecainide. No attempt was made to limit fluoroscopy time in our study population. Nevertheless, despite data acquisition from 120-320 anatomically distinct sites during global and more detailed focal atrial mapping, total fluoroscopy exposure was typically < 30 minutes and was as little as 12 minutes. The detailed display capabilities of the CARTO system appear to offer the potential of enhancing our understanding of atrial anatomy, atrial activation, and their relationship to surface ECG P wave morphology during focal atrial tachycardias.

Electro-anatomic mapping of the sinoatrial activation: initial experiences with the new CARTO mapping system

Prerequisite for successful radiofrequency catheter ablation on tachycardias is the exact mapping during the electrophysiologic study. The new mapping system CARTO allows a three-dimensional color-coded electroanatomic map of impulse propagation using electromagnetic technology. Mapping of sinuatrial activation in the right atrium of 11 patients represents the first clinical experience with this new system. The physiological activation sequence could be determined in all patients three-dimensionally, and the sinus node could be localized as a physiological activation focus with interindividual variability only in the sagital plane without complications. The nonfluoroscopic mapping system allows high resolution visualization of electrical activity and may therefore improve precision and simplify the determination of the arrhythmogenic substrate during tachycardias for successful catheter ablation.