Expert-enhanced machine learning for cardiac arrhythmia classification.

We propose a new method for the classification task of distinguishing atrial fibrillation (AFib) from regular atrial tachycardias including atrial flutter (AFlu) based on a surface electrocardiogram (ECG). Recently, many approaches for an automatic classification of cardiac arrhythmia were proposed and to our knowledge none of them can distinguish between these two. We discuss reasons why deep learning may not yield satisfactory results for this task. We generate new and clinically interpretable features using mathematical optimization for subsequent use within a machine learning (ML) model. These features are generated from the same input data by solving an additional regression problem with complicated combinatorial substructures. The resultant can be seen as a novel machine learning model that incorporates expert knowledge on the pathophysiology of atrial flutter. Our approach achieves an unprecedented accuracy of 82.84% and an area under the receiver operating characteristic (ROC) curve of 0.9, which classifies as "excellent" according to the classification indicator of diagnostic tests. One additional advantage of our approach is the inherent interpretability of the classification results. Our features give insight into a possibly occurring multilevel atrioventricular blocking mechanism, which may improve treatment decisions beyond the classification itself. Our research ideally complements existing textbook cardiac arrhythmia classification methods, which cannot provide a classification for the important case of AFib↔AFlu. The main contribution is the successful use of a novel mathematical model for multilevel atrioventricular block and optimization-driven inverse simulation to enhance machine learning for classification of the arguably most difficult cases in cardiac arrhythmia. A tailored Branch-and-Bound algorithm was implemented for the domain knowledge part, while standard algorithms such as Adam could be used for training.

[Surface ECG characteristics of right and left atrial flutter]. / Oberflächen-EKG-Charakteristika von rechts- und linksatrialem Vorhofflattern.

INTRODUCTION: Atrial tachycardia in virtually all areas of both atria has become more important in the clinical management of patients with previous complex atrial fibrillation ablation. Accurate interpretation of surface electrocardiogram (ECG) characteristics is of paramount importance to localize the origin of atrial tachycardia, particularly for planning interventional treatment. This article highlights the ECG features of different types of right and left atrial tachycardia. DEFINITION: Typical right atrial flutter through the cavotricuspid isthmus conducts septally in a cranial direction and demonstrates sawtooth-like flutter waves which start negative in II, III and aVF and then show a steep slope upwards to the isoelectric line. The flutter rate typically ranges between 240-250 beats/min. In contrast, right atrial flutter in a clockwise rotation, flutter around the vena cava inferior or superior and around a scar (e.g. after cardiac surgery) show positive or biphasic flutter waves (lower or upper loop reentry). Left atrial flutter waves (e.g. around the mitral valve or around the pulmonary veins) are very heterogeneous and are typically positive in V1 as the left atrium is located in the posterior mediastinum. CONCLUSION: Specific knowledge of flutter wave morphology in surface ECG facilitates planning and performance of the ablation strategy.

Atrial flutter: more than just one of a kind.

Since its first description about one century ago, our understanding of atrial flutter (AFL) circuits has considerably evolved. One AFL circuit can have variable electrocardiographic (ECG) manifestations depending on the presence of pre-existing atrial lesions, or impaired atrial substrate. Conversely, different (right sided or even left sided) atrial circuits including different mechanisms (macroreentrant, microreentrant, or focal) can present with a very similar surface ECG manifestation. The development of efficient high-resolution electroanatomical mapping systems has improved our knowledge about AFL mechanisms, as well as facilitated their curative treatment with radiofrequency catheter ablation. This article will review ECG features for typical and atypical flutters, and emphasize the limitations for circuit location from the surface ECG.

Application of higher order spectra for accurate delineation of atrial arrhythmia.

The electrocardiogram (ECG) is being commonly used as a diagnostic tool to distinguish different types of atrial tachyarrhythmias. The inherent complexity and mechanistic and clinical inter-relationships often brings about diagnostic difficulties to treating physicians and primary health care professionals creating frequent misdiagnoses and cross classifications using visual criteria. The current paper presents a methodology for ECG based pattern analysis for detection of atrial flutter, atrial fibrillation and normal sinus rhythm beats. ECG is an inherently non-linear and non-stationary signal; its variation may contain indicators of current disease, or warnings about impending cardiac diseases. Routinely used time domain and frequency domain methods will not be able to capture the hidden information present in the ECG beats. In the present study, we have used non-linear features of higher order spectra (HOS) to differentiate the normal, atrial fibrillation and atrial flutter ECG beats. The bispectrum features were subjected to independent component analysis (ICA) for data reduction. The ICA coefficients were subsequently subjected to K-nearest-neighbor (KNN), classification and regression tree (CART) and neural network (NN) classifiers to evaluate the best automated classifier. We have obtained an average accuracy of 97.65%, sensitivity and specificity of 98.75% and 99.53% respectively using ten-fold cross validation. Overall, the results show that application of higher order spectra statistics is useful for the classification of atrial tachyarrhythmias with reasonably high accuracies. Further validation of the proposed technique will yield acceptable results for clinical implementation.

Revisit of typical counterclockwise atrial flutter wave in the ECG: electroanatomic studies on the determinants of the morphology.

BACKGROUND: Cavotricuspid isthmus-dependent counterclockwise atrial flutter (typical AFL) is characterized by negative saw-tooth morphology flutter wave (F-wave) in the inferior leads, which is classified as type 1 with purely negative F-wave without positive terminal deflection (PTD), type 2 with small PTD, and type 3 with broad PTD. The determinants of these morphological differences remain to be elucidated. METHODS AND RESULTS: Of 72 patients (58 males, 65 ± 13 years) with typical AFL, 19 were classified as type 1 and 53 as types 2 and 3. We created an electroanatomic map of the right atrium (RA) during AFL and determined which RA site activation corresponded to which F-wave component by analyzing the activation map. It was revealed that F-wave component from the nadir to terminal deflection point coincided with the cranio-caudal activation of the RA free wall (RAFW) in all types. The bipolar voltage map showed that type 1 had the greater extent of low voltage (<0.5 mV) area (LVA) in RAFW (39 ± 24%) than types 2 and 3 (4 ± 3%) (P < 0.0001), explaining the absence of PTD in type 1. In types 2 and 3, F-wave amplitude determining the PTD magnitude was highly correlated with the longitudinal distance between two points on RAFW corresponding to the nadir and peak of F-wave (r = 0.73, P < 0.0001). CONCLUSIONS: Terminal positivity and amplitude of F-wave in typical AFL are primarily related to the RAFW activity: negatively by the extent of LVA and positively by the longitudinal vector of activation.

Prospective observations in the clinical and electrophysiological characteristics of intra-isthmus reentry.

INTRODUCTION: Intra-isthmus reentry (IIR) is a circuit within the cavotricuspid isthmus (CTI). The purpose of this study is to prospectively define the electrogram and surface ECG characteristics of IIR, and its clinical implications. METHODS AND RESULTS: Fourteen patients underwent electrophysiological studies and were found to have IIR. Detailed electrogram mapping of the CTI was available in all, electroanatomic mapping (EAM) in 8 of 14 (57%) patients. In all, entrainment mapping during tachycardia proved reentry, and showed that the anteroinferior CTI was out of the circuit and the septal CTI was in the circuit in 12 of 14 patients, whereas in 2, the circuit was confined within the mid and/or anteroinferior CTI. Fractionated potentials (FPs) spanning 34-71% of the tachycardia cycle length were recorded within the CTI in all, and double potentials were inscribed in 10 of 14 (71%). Analysis of the tricuspid annulus electrograms showed spontaneous shifts from a counterclockwise (CCW) to clockwise or fusion patterns. Surface ECGs showed either typical CCW pattern (12 patients) or atypical patterns (3 patients). The EAMs showed a focal pattern in 3, a CCW pattern in 5. The successful ablation site always occurred at the area with maximal FP duration. Over the same period, 33 of 384 (9%) patients who underwent ablation for CTI-dependent flutter had prior successful CTI ablation, 7 of 33 (21%) were found to have IIR during the redo procedure. CONCLUSIONS: (1) Electrogram and ECG patterns of IIR frequently show atypical flutter. (2) IIR was successfully ablated in an area of the CTI associated with maximal duration of FPs. (3) IIR is a significant cause of "recurrent flutter" in patients with prior CTI ablation.

[Typical atrial flutter: classification, clinical manifestations, diagnosis, and treatment].

Main etiological factors, mechanisms of arrhythmogenesis and classification of atrial flutter (AFl) are presented. Clinical electrocardiographical and electrophysiological features of typical AFl are described. Main diagnostic measures are delineated and principles of tactical approach to management of patients with typical AFl presented. Indications to radiofrequency catheter ablation, and physical characteristics of radiofrequency interventions in lower isthmus of the right atrium are discussed. Data of analysis of comparative efficacy of pharmacological and interventional approaches to management of patients with typical AFl as well as spectrum of possible complications associated with surgery are also presented.

Atrial flutter versus atrial fibrillation in a general population: differences in comorbidities associated with their respective onset.

OBJECTIVE: Determine and compare the prevalence of known risk factors for cardiovascular disease among unselected individuals presenting with their first ever episode of atrial flutter (AFL) and atrial fibrillation (AF). STUDY DESIGN AND SETTING: We evaluated 11 pre-selected clinical variables including age, sex, smoking history and other potential cardiac risk factors. Using the resources of the Marshfield Epidemiologic Study Area, a population-based database, all newly diagnosed cases of either AFL or AF in the region during a 4-year period were identified. RESULTS: Among the 472 incident cases, 76 (16.1%) had AFL and 396 (83.9%) had AF. Compared to those with AF, subjects with AFL were more likely to have had a history of chronic obstructive pulmonary disease (25% vs. 12%, P = 0.006), heart failure (28% vs. 17%, P = 0.05), and smoking (49% vs. 37%, P = 0.06). Hypertension, on the other hand, was more common among individuals with AF (63% vs. 47%, P = 0.01). CONCLUSION: This study represents the first report to evaluate potential differences in the conditions associated with the development of AFL versus AF. Research into the mechanisms of atrial arrhythmogenesis may lead to improved preventive and therapeutic interventions.

Cardiac arrhythmia classification using wavelets and Hidden Markov Models - a comparative approach.

This paper reports a comparative study of feature extraction methods regarding cardiac arrhythmia classification, using state of the art Hidden Markov Models. The types of beat being selected are normal (N), premature ventricular contraction (V) which is often precursor of ventricular arrhythmia, two of the most common class of supra-ventricular arrhythmia (S), named atrial fibrillation (AF), atrial flutter (AFL), and normal rhythm (N). The considered feature extraction methods are the standard linear segmentation and wavelet based feature extraction. The followed approach regarding wavelets was to observe simultaneously the signal at different scales, which means with different level of focus. Experimental results are obtained in real data from MIT-BIH Arrhythmia Database and show that wavelet transform outperforms the conventional standard linear segmentation.

Current concepts and management strategies in atrial flutter.

After atrial fibrillation, atrial flutter (AFL) is the most important and most common atrial tachyarrhythmia. Atrial flutter describes an electrocardiographic model of atrial tachycardia >or=240/min, with a uniform and regular continuous wave-form. There is classically a 2:1 conduction across the atrioventricular (AV) node; as a result, the ventricular rate is usually one-half the flutter rate in the absence of AV node dysfunction. AFL can be harmful by impairing the cardiac output and by encouraging atrial thrombus formation that can lead to systemic embolization. There are four major concerns that must be addressed in the treatment of AFL: reversion to normal sinus rhythm (NSR); maintenance of NSR; control of the ventricular rate; and prevention of systemic embolization. Our review will highlight strategies for reverting patients back to NSR and then maintaining them in NSR, with emphasis on the recent updates, including the role of ablation in the management of atrial flutter.

Role of the right atrial substrate in different types of atrial arrhythmias.

BACKGROUND: The regional distribution of the low-voltage zones (LVZs) may relate to the maintenance of atrial arrhythmias in the right atrium (RA). OBJECTIVES: The purpose of this study was to investigate the RA substrate characteristics in different types of atrial arrhythmias originating from RA and left atrium (LA). METHODS: Forty-five patients (35 men, age = 62 +/- 15 years) with RA atypical atrial flutter (n = 15, group 1), RA atrial fibrillation (AF; n = 15, no PV initiating foci, group 2), and LA AF (n = 1 5, no RA arrhythmias, group 3) referred for three-dimensional EnSite mapping were included. Voltage and activation maps were visualized. RESULTS: The mean voltage of the RA was lower in group 2, and compared with group 3, a voltage reduction during atrial pacing was evident in groups 1 and 2. The fixed LVZs (independent of the rhythm) were mostly located along the lower crista terminalis (CT). A functional extension of the LVZ was located on the CT in 84% of patients, sinus venosa in 18%, and free-wall region in 27%, forming the borders of the slow conduction isthmus for the reentrant circuits. The number of slow conduction isthmuses was 1.3 +/- 0.9, 2.2 +/- 1.0, and 0.87 +/- 0.74, for the groups 1-3 patients, respectively (P <.05). Radiofrequency ablation connecting the LVZs successfully eliminated those isthmuses. The long-term follow-up revealed that 66% of the patients remained in sinus rhythm. CONCLUSIONS: Single and multiple slow conduction isthmuses bordered by the fixed and functional LVZs were critical for the reentrant circuits in the RA. The conduction isthmuses could be identified by their substrate characteristics and ablated successfully.

Acute and long-term efficacy and safety of catheter cryoablation of the cavotricuspid isthmus for treatment of type 1 atrial flutter.

BACKGROUND: Atrial flutter (AFL) is commonly treated by radiofrequency catheter ablation. Catheter-based cryoablation may be an effective alternative with potential advantages. OBJECTIVE: The purpose of this study was to study the acute and long-term safety and efficacy of catheter-based cryoablation for treatment of cavotricuspid isthmus-dependent (typical and reverse typical) AFL. METHODS: Catheter-based cryoablation was performed with a 10Fr catheter in 160 patients with cavotricuspid isthmus-dependent AFL (122 men and 38 women; mean age 63.1 +/- 9.3 years, mean left ventricular ejection fraction 54.6% +/- 10.4%); 94 (58.8%) of these patients also had atrial fibrillation (AF). All patients underwent right atrial (RA) activation mapping and pacing at the cavotricuspid isthmus to demonstrate concealed entrainment and confirm cavotricuspid isthmus dependence of AFL. Catheter-based cryoablation of the cavotricuspid isthmus was performed with multiple freezes (average freeze time 2.3 +/- 0.5 minutes) until bidirectional block was demonstrated during pacing from the low lateral RA and coronary sinus, respectively. Patients were evaluated at 1, 3, and 6 months and underwent weekly and symptomatic event monitoring. Acute procedural success was defined as cavotricuspid isthmus block persisting 30 minutes after ablation. Long-term success was defined as absence of AFL during follow-up. RESULTS: Acute success was achieved in 140 (87.5%) of 160 patients. Total procedure time was 200 +/- 71 minutes, ablation time (including a 30-minute waiting period after ablation) was 139 +/- 62 minutes, and fluoroscopy time was 35 +/- 26 minutes. An average of 20.5 +/- 11.3 freezes, for a total ablation time of 47.4 +/- 24.3 minutes, were required to achieve cavotricuspid isthmus block, with average and nadir temperatures of -81.5 degrees C +/- 3.7 degrees C and -85.6 degrees +/- 3.6 degrees C, respectively. Four patients (2.5%) had procedure-related adverse events. Of 132 patients with acute efficacy who completed 6-month follow-up, 8 (6%) were lost to follow-up or were noncompliant with event recordings. Using survival analysis, 106 (80.3%) remained free of AFL on strict analysis of event recordings only, and 119 (90.2%) remained clinically free of AFL. CONCLUSION: This large pivotal study demonstrated the acute and long-term efficacy and safety of catheter-based cryoablation for cavotricuspid isthmus-dependent AFL, similar to rates previously reported for radiofrequency catheter ablation.

Anatomic and electrophysiologic differences between chronic and paroxysmal atrial flutter: intracardiac echocardiographic analysis.

BACKGROUND: It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia. PURPOSE: The aim of the study was to compare intracardiac echocardiographic (ICE) images of the crista terminalis (CT) and transverse conduction properties of the CT between chronic and paroxysmal forms of common AFL. METHODS: Chronic AFL (n = 7) was defined as non-self-terminating AFL lasting >1 month, and paroxysmal AFL (n = 8) was defined as an intermittent arrhythmia with symptomatic episodes of 24 hours maximum duration. ICE images of the right atrium were recorded with a 9 F 9-MHz intracardiac ultrasound catheter during pullback at 0.5-mm intervals from the superior vena cava to the inferior vena cava triggered by electrocardiogram and respiration. The two-dimensional image of the right atrium was reconstructed into a three-dimensional (3-D) image. RESULTS: Three-dimensional images from patients with chronic AFL showed the CT to be thick and continuous, and conduction across the CT was blocked at a pacing rate just above sinus rhythm in all seven patients. In contrast, 3D images from paroxysmal AFL showed the CT to be thin and discontinuous, and conduction across the CT during midseptal pacing was observed in five of the eight patients. CONCLUSION: The nature of AFL is determined, at least in part, by anatomic and electrophysiologic characteristics of the CT.

Pharmacological therapy in children with atrial fibrillation and atrial flutter.

Heart rhythm disorders in children are not different, on electrocardiographic trace, from heart rhythm disorders in adults with the exception of incidence which is different according to the age. Paticularly, atrial flutter (FlA) and fibrillation (FA) are very uncommon arrhythmias in the general pediatric population. Generally atrial fibrillation and atrial flutter, in our experience, is a temporary heart rhythm disturbance connected to specifical and resovable reasons with the exception of Fontain's surgical correction of congenital heart diseases or cardiopathies with dilatation of both atria. Presenting symptoms, symptom history (e.g., frequency, duration, and severity), risk assessment, previous response to alternative treatment options, convenience and patient preference for a specific treatment option, and costeffectiveness of a treatment option are among the many factors that should be considered. Treatment of atrial flutter and fibrillation in pediatric age involves several options: Pharmacological therapy, Transoesophageal atrial pacing (TEAP), Electrical cardioversion and Catheter ablation. In this review we evaluated the physiopathology, the clinical features and the current terapeutical strategies for these arrythmias in paediatric age.

[Typical atrial flutter: history, mechanisms and radiofrequency "ablation"]. / Le flutter auriculaire typique: histoire, mécanismes et "ablation" par la technique de radiofréquence.

yipical atrial flutter can now be permanently cured by a single session of radiofrequency ablation, a non pharmacological technique. The term "atrial flutter" is in fact somewhat confusing. A review of the history of this form of tachycardia shows that atrial flutter is indeed a multiple entity. While the reentrant nature of atrial flutter has long been known, most cardiologists refer to the typical ECG aspect and right atrial macro reentry circuit with counterclockwise rotation, as described by Puech. It is now possible to classify these flutters according to their electrocardiographic aspect and electrophysiological mechanisms. This article describes the diagnostic signs of typical flutter, and provides a detailed description of the most frequently used radical therapy, namely catheter ablation of the cavotricuspidian isthmus. This technique delivers radiofrequency pulses, under continuous local temperature monitoring, in order to permanently interrupt conduction in this structure. Outcome is assessed with the pacing technique and local electrocardiography. In experienced hands the immediate success rate is very high, late recurrence is rare, and complications are virtually absent.

[Atrial flutter: an update]. / Flúter auricular: perspectiva clínica actual.

Invasive electrophysiologic studies have changed the clinical outlook for patients with atrial flutter. Recognition of the reentrant circuit responsible for typical atrial flutter has led to the development of catheter ablation techniques that can prevent recurrence in >90% of cases. In addition, general understanding of atrial tachycardias has changed radically, such that ECG-based classifications are now obsolete. Atypical reentrant circuits associated with surgical scars or fibrotic areas in either atrium, which are indistinguishable from focal tachycardias on ECG, have been identified. These circuits also seem amenable to treatment by ablation. Recently, a new type of reentrant tachycardia that could be problematic in the future has emerged in patients who have undergone extensive left atrial ablation for the treatment of atrial fibrillation. These atypical circuits can be characterized using the mapping and entrainment techniques initially developed for typical flutter. In these cases, electroanatomical mapping, involving the construction of a virtual anatomical model of the atria, is extremely helpful. Despite the success of ablation, long-term prognosis is frequently overshadowed by the appearance of atrial fibrillation, which suggests that flutter and fibrillation share a common arrhythmogenic origin that is not modified by cavotricuspid isthmus ablation. In contrast with our clear electrophysiologic understanding of atrial flutter, little is known about the natural history of the condition because the literature has traditionally grouped patients with flutter and fibrillation together. Consequently, the complex relationship between the two arrhythmias has still to be clearly delineated. Primary prevention and preventing the development of atrial fibrillation after ablation remain outstanding clinical challenges.

Flúter auricular: perspectiva clínica actual / Atrial Flutter: an Update

Los estudios electrofisiológicos invasivos han cambiado la perspectiva clínica de los pacientes con flúter auricular. El conocimiento de la estructura del circuito de flúter típico ha permitido desarrollar técnicas de ablación con catéter que eliminan las recidivas en > 90% de los casos. También ha cambiado el concepto global de las taquicardias auriculares, lo que ha hecho obsoletas las clasificaciones basadas en el electrocardiograma. Se han demostrado circuitos reentrantes atípicos basados en cicatrices quirúrgicas o en zonas fibróticas en ambas aurículas, que son también asequibles a tratamiento por ablación y que en el electrocardiograma son indistinguibles de una taquicardia focal. La ablación amplia de la aurícula izquierda para el tratamiento de la fibrilación auricular está dando lugar a un nuevo tipo de taquicardias reentrantes que puede ser problemático en el futuro. Las técnicas de mapeo y encarrilamiento de los circuitos descritas inicialmente en el flúter permiten definir estos circuitos. El mapeo electroanatómico, que construye moldes anatómicos virtuales de las aurículas, es de gran ayuda en estos casos. A pesar del éxito de la ablación, el pronóstico a largo plazo se ensombrece con frecuencia por la aparición de fibrilación auricular, lo que indica que hay un sustrato arritmogénico común al flúter y la fibrilación, que la ablación del istmo cavotricuspídeo no cambia. En contraste con la clara definición electrofisiológica, hay escasa información sobre el curso clínico del flúter, ya que tradicionalmente la bibliografía se refiere a grupos de «flúter y fibrilación auricular» y las complejas relaciones entre ambas arritmias quedan aún por revelar claramente. La prevención primaria y la prevención de la aparición de fibrilación auricular tras la ablación son retos pendientes (AU)

Invasive electrophysiologic studies have changed the clinical outlook for patients with atrial flutter. Recognition of the reentrant circuit responsible for typical atrial flutter has led to the development of catheter ablation techniques that can prevent recurrence in >90% of cases. In addition, general understanding of atrial tachycardias has changed radically, such that ECG-based classifications are now obsolete. Atypical reentrant circuits associated with surgical scars or fibrotic areas in either atrium, which are indistinguishable from focal tachycardias on ECG, have been identified. These circuits also seem amenable to treatment by ablation. Recently, a new type of reentrant tachycardia that could be problematic in the future has emerged in patients who have undergone extensive left atrial ablation for the treatment of atrial fibrillation. These atypical circuits can be characterized using the mapping and entrainment techniques initially developed for typical flutter. In these cases, electroanatomical mapping, involving the construction of a virtual anatomical model of the atria, is extremely helpful. Despite the success of ablation, long-term prognosis is frequently overshadowed by the appearance of atrial fibrillation, which suggests that flutter and fibrillation share a common arrhythmogenic origin that is not modified by cavotricuspid isthmus ablation. In contrast with our clear electrophysiologic understanding of atrial flutter, little is known about the natural history of the condition because the literature has traditionally grouped patients with flutter and fibrillation together. Consequently, the complex relationship between the two arrhythmias has still to be clearly delineated. Primary prevention and preventing the development of atrial fibrillation after ablation remain outstanding clinical challenges (AU)

Usefulness and limitations of the surface electrocardiogram in the classification of right and left atrial flutter.

Atrial flutter is a common arrhythmia that may cause significant symptoms, including palpitations, dyspnoea, chest pain and even syncope. Frequently, it is possible to diagnose atrial flutter with a 12-lead surface electrocardiogram (ECG), looking for distinctive waves in leads II, III, aVF, aVL, V1 and V2. Puech and Waldo developed the first classification of atrial flutter in the 1970s. These authors divided the dysrhythmia into types I and II. Therefore, in 2001, the European Society of Cardiology and the North American Society of Pacing and Electrophysiology developed a new classification of atrial flutter based not only on the ECG, but also on the electrophysiological mechanism. More recently, Scheinman and colleagues have provided an updated classification and nomenclature. Terms such as common, uncommon, typical, reverse typical or atypical flutter are abandoned, because they may generate confusion. The authors worked out a new terminology, which differentiates atrial flutter only on the basis of electrophysiological mechanism.

Comparação entre a atenuação de sinal nos mapas eletroanatômicos de voltagem e a presença de bloqueio de condução em istmo atrial direito durante ablação por radiofreqüência em pacientes com flutter atrial / Correlation between signal attenation on electroanatomic voltage maps and conduction block in the rigth atrial isthmus radiofrequency ablation of atrial flutter

Objetivo: Avaliar a comparação entre a presença de atenuação intensa do sinal intracavitário através do mapeamento eletroanatômico e a presença de bloqueio de condução no istmo atrial direito em pacientes submetidos à ablação de flutter atrial. Métodos: Foram estudados vinte e oito pacientes sucessivos encaminhados para ablação de flutter istmo-dependente. A idade média foi de 60,96 anos, com 82,1 por cento dos pacientes do sexo masculino. Mapas eletroanatômicos de condução e voltagem foram gerados pré e pós-ablação e a presença de bloqueio de condução foi comparada com a atenuação do sinal intracavitário na região ablacionada. Foi considerada como atenuação intensa ("fibrose"), sinais menor que 0,1mV e tecido normal aquele com sinal maior que 1mV. Resultados: A média de 71,43 pontos foi utilizada para a construção de cada mapa, com desvio-padrão de 43,93 pontos. Os mapas construídos apresentaram um volume com média de 142,14mL e desvio-padrão de 32,6mL. O número de mapas construído por paciente variou de 3 a 5, com média e desvio-padrão de 33,3 maior ou menor que 0,6. O sucesso imediato da ablação nesta população estudada foi de 82,14 por cento (23/28). O valor de p encontrado na comparação entre atenuação da voltagem do sinal intracavitário ("fibrose") na região istmal e a presença de bloqueio de condução nesta área foi de 0,063. Conclusões: A metodologia empregada de análise de voltagem dos sinais intracavitários não se mostrou confiável em predizer a presença de bloqueio de condução istmal