Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D) - What We Have Learned after 40 Years of the Diagnosis of This Clinical Entity.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) was initially recognized as a clinical entity by Fontaine and Marcus, who evaluated a group of patients with ventricular tachyarrhythmia from a structurally impaired right ventricle (RV). Since then, there have been significant advances in the understanding of the pathophysiology, manifestation and clinical progression, and prognosis of the pathology. The identification of genetic mutations impairing cardiac desmosomes led to the inclusion of this entity in the classification of cardiomyopathies. Classically, ARVC/D is an inherited disease characterized by ventricular arrhythmias, right and / or left ventricular dysfunction; and fibro-fatty substitution of cardiomyocytes; its identification can often be challenging, due to heterogeneous clinical presentation, highly variable intra- and inter-family expressiveness, and incomplete penetrance. In the absence of a gold standard that allows the diagnosis of ARVC/D, several diagnostic categories were combined and recently reviewed for a higher diagnostic sensitivity, without compromising the specificity. The finding that electrical abnormalities, particularly ventricular arrhythmias, usually precede structural abnormalities is extremely important for risk stratification in positive genetic members. Among the complementary exams, cardiac magnetic resonance imaging (CMR) allows the early diagnosis of left ventricular impairment, even before morpho-functional abnormalities. Risk stratification remains a major clinical challenge, and antiarrhythmic drugs, catheter ablation and implantable cardioverter defibrillator are the currently available therapeutic tools. The disqualification of the sport prevents cases of sudden death because the effort can trigger not only the electrical instability, but also the onset and progression of the disease.

Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D) - What We Have Learned after 40 Years of the Diagnosis of This Clinical Entity / Cardiomiopatia/Displasia Arritmogênica do Ventrículo Direito (C/DAVD) - O Que Aprendemos após 40 Anos do Diagnóstico desta Entidade Clínica

Abstract Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) was initially recognized as a clinical entity by Fontaine and Marcus, who evaluated a group of patients with ventricular tachyarrhythmia from a structurally impaired right ventricle (RV). Since then, there have been significant advances in the understanding of the pathophysiology, manifestation and clinical progression, and prognosis of the pathology. The identification of genetic mutations impairing cardiac desmosomes led to the inclusion of this entity in the classification of cardiomyopathies. Classically, ARVC/D is an inherited disease characterized by ventricular arrhythmias, right and / or left ventricular dysfunction; and fibro-fatty substitution of cardiomyocytes; its identification can often be challenging, due to heterogeneous clinical presentation, highly variable intra- and inter-family expressiveness, and incomplete penetrance. In the absence of a gold standard that allows the diagnosis of ARVC/D, several diagnostic categories were combined and recently reviewed for a higher diagnostic sensitivity, without compromising the specificity. The finding that electrical abnormalities, particularly ventricular arrhythmias, usually precede structural abnormalities is extremely important for risk stratification in positive genetic members. Among the complementary exams, cardiac magnetic resonance imaging (CMR) allows the early diagnosis of left ventricular impairment, even before morpho-functional abnormalities. Risk stratification remains a major clinical challenge, and antiarrhythmic drugs, catheter ablation and implantable cardioverter defibrillator are the currently available therapeutic tools. The disqualification of the sport prevents cases of sudden death because the effort can trigger not only the electrical instability, but also the onset and progression of the disease.

Resumo A cardiomiopatia/displasia arritmogênica do ventrículo direito (C/DAVD) foi inicialmente reconhecida como uma entidade clínica por Fontaine e Marcus que avaliaram um grupo de pacientes com taquiarritmia ventricular proveniente de um ventrículo direito (VD) estruturalmente comprometido. Desde então, houve avanços significativos na compreensão da fisiopatologia, manifestação e evolução clínica e prognóstico da patologia. A identificação de mutações genéticas comprometendo os desmossomos cardíacos levou a inclusão desta entidade na classificação das cardiomiopatias. Classicamente, a C/DAVD é uma doença hereditária que se caracteriza por arritmias ventriculares, disfunção ventricular direita e/ou esquerda; e substituição fibro-gordurosa dos cardiomiócitos; cuja identificação pode ser muitas vezes desafiadora, devido à apresentação clínica heterogênea, expressividade intra- e inter-familiar altamente variável e penetrância incompleta. Na falta de um padrão-ouro que permita o diagnóstico da C/DAVD, várias categorias diagnósticas foram combinadas e, recentemente revisadas buscando uma maior sensibilidade diagnóstica, sem comprometer a especificidade. A descoberta de que as anormalidades elétricas, particularmente as arritmias ventriculares, geralmente precedem anormalidades estruturais é extremamente importante para a estratificação de risco em membros genéticos positivos. Entre os exames complementares, a ressonância magnética cardíaca (RMC) possibilita o diagnóstico precoce de comprometimento ventricular esquerdo, mesmo antes das anormalidades morfofuncionais. A estratificação de risco continua a ser um grande desafio clínico e medicamentos antiarrítmicos, ablação de cateter e desfibrilador cardioversor implantável são as ferramentas terapêuticas atualmente disponíveis. A desqualificação do esporte previne casos de morte súbita uma vez que o esforço pode desencadear não só a instabilidade elétrica, mas também deflagrar o início e a progressão da doença.

Long-term efficacy of low doses of quinidine on malignant arrhythmias in Brugada syndrome with an implantable cardioverter-defibrillator: a case series and literature review.

BACKGROUND: To prevent the recurrence of ventricular arrhythmias (VA) in Brugada syndrome (BrS), only quinidine has been consistently reported to have a beneficial effect. Recommended doses are ≥ 1 g/d. The efficacy of lower doses of quinidine has been suggested on the basis of a few isolated experiences. OBJECTIVES: To describe the efficacy and safety of doses ≤ 600 mg/d of quinidine after cardioverter-defibrillator implantation in BrS at 2 referral centers and to compare those results with a comprehensive review of the literature. METHODS: In a retrospective analysis of medical records from the 2 centers, 6 men with BrS who received ≤ 600 mg/d of quinidine sulfate or hydroquinidine after cardioverter-defibrillator implantation were identified. Quinidine was initiated after arrhythmic syncope or appropriate shocks, including arrhythmic storm in 4. A literature search was performed to find previous cases with symptomatic BrS reported as having received ≤ 600 mg/d of quinidine. RESULTS: Quinidine prevented recurrence of VA in all patients from our series without side effects during a median follow-up of 4 years (from 2 to 8 years). In the literature review, 14 additional adults were found. With the exception of 3, quinidine effectively suppressed arrhythmic events in all of them. Four subjects who discontinued the medication experienced VA recurrence, successfully treated by restarting quinidine. CONCLUSIONS: Low doses of quinidine were well tolerated and effective to prevent the recurrence of VA, including arrhythmic storm, in subjects with BrS with an implantable cardioverter-defibrillator. Effectiveness of quinidine or hydroquinidine in doses ≤ 600 mg/d is 85%.

Post-ablation prolongation of atrioventricular nodal refractory period is correlated with long-term success of cryoablation for atrioventricular nodal reentrant tachycardia in the case of the persistence of a residual jump.

PURPOSE: A residual slow pathway after successful cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is correlated with a higher recurrence rate. We described determinants of recurrence in subjects with a residual jump. METHODS: We analyzed the data of subjects with acute successful slow pathway cryoablation for AVNRT using a 6-mm-tip cryocatheter. Success was defined as AVNRT non-inducibility. Patients with no baseline elicitable jump, no inducible AVNRT, and transient first atrioventricular (AV) block at the last site were excluded. RESULTS: From 371 patients who underwent cryoablation from May 2002 to March 2011, 303 fulfilled the entry criteria (mean age, 41 ± 16; 222 women). Baseline AV nodal effective refractory period (ERP) was 272 ± 57 ms, postprocedural 331 ± 64 (P < 0.001), and the mean of the difference (Δ ERP) 60 ± 41. At the end of the procedure, 64 patients (21 %) had a residual jump, of whom 22 with a single echo. At 12 months follow-up, the actuarial recurrence-free rate was 70.3 % in patients with a residual jump and 86 % in those without (P = 0.01). In patients with a jump, only Δ AV nodal ERP was correlated with recurrence (37 ± 41 vs. 68 ± 47 ms; P < 0.04) while a single echo was not. The actuarial rate of recurrence was 60.8 % in patients with a Δ AV nodal ERP ≤ 30 ms and 18.8 % in those with a Δ AV nodal ERP >30 ms (P < 0.01). CONCLUSIONS: Suppression of slow pathway conduction is the optimal endpoint for AVNRT cryoablation. A residual jump can be tolerated if AV nodal ERP postcryoablation is prolonged >30 ms.

Correlations between long-term results after cryoablation for atrioventricular nodal reentry tachycardia and a residual jump associated or not with a single echo.

AIMS: While in radiofrequency ablation for atrioventricular nodal reentry tachycardia (AVNRT) a residual jump and a single echo do not seem to substantially modify long-term results, in cryoablation procedures their effects are still under evaluation. The purpose of this study was to evaluate if a residual jump associated or not with an isolated echo is correlated with outcome. INCLUSION CRITERIA: acute successful slow pathway cryoablation for slow-fast AVNRT. EXCLUSION CRITERIA: use of a 4 mm tip cryocatheter, no baseline elicitable jump or inducible AVNRT, and unwanted persistent first degree atrioventricular (AV) block at the end of the procedure. Cryoablation (-80°C × 4 min) was applied after successful cryomapping. Atrioventricular nodal reentry tachycardia inducibility was checked 30 min later on and off isoproterenol. Acute success was defined as AVNRT non-inducibility. Among 332 patients (pts) who had undergone cryoablation from May 2002 to March 2010 in our institutions, 245 of them fulfilled the entry criteria (173 women, mean age 41 ± 16 years, ineffective drugs 1.3 ± 1.1). A 7-Fr 6-mm tip cryocatheter (CryoCath®) was used in all cases. Baseline AV nodal effective refractory period (ERP) was 271 ± 55 ms, post-procedural ERP 331 ± 60 ms (P< 0.001), and the mean of the difference between baseline and post-procedural ERP 63 ± 38 ms. A/V ratio at successful site was 1 ± 0.4. Forty-four pts (18%) had a residual jump at the end of the procedure, and 14 of them had an associated single echo. Global cryoapplication time was 993 ± 797 s. During a follow-up of 40 ± 10 months, 43 pts (17.5%) had recurrences. At 12 months follow-up, actuarial rate of recurrence-free pts was 85% in the group without residual jump (201 pts), 63.3% with residual jump and no echo (30 pts), and 60.6% with residual jump associated with a single echo (P< 0.003 among groups). Univariate predictors of recurrences were persistence of a residual jump (P< 0.001) and total cryoapplication time (P< 0.02). In a multivariate model, only residual jump was independently correlated with recurrences (P< 0.01). CONCLUSIONS: In patients undergoing AVNRT cryoablation, slow-pathway suppression is correlated with a better outcome. A single echo is associated with a recurrence risk similar to residual jump without echo. It may be suggested that pursuing a procedural endpoint up to slow pathway complete suppression may improve long-term success.

Cryoablation of atrioventricular nodal reentrant tachycardia: a clinical review.

Slow-pathway ablation is the treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT). Cryoablation is effective and safe, but its widespread use seems to be limited by a slightly lower long-term clinical efficacy when compared to radiofrequency (RF) ablation. However, the occurrence of atrioventricular block requiring permanent pacing with RF remains clinically relevant (about 1%). This review summarizes current experiences accumulated during the last decade with cryotechnology in terms of acute and long-term results for AVNRT and compares it with those of RF ablation. We describe the advantages of cryo compared to RF ablation. Our data suggest that pursuing procedural endpoint up to slow pathway complete ablation may improve long-term clinical success of cryoablation. We also focus on potential benefit that can be expected by using cryocatheters leading to larger and deeper freeze. For high-risk ablations, cryoenergy should be used systematically.

Catheter cryoablation of atrio-ventricular nodal reentrant tachycardia. A clinical review.

Cryoablation is a new method in interventional cardiac electrophysiology for percutaneous catheter ablation of cardiac arrhythmias. Cryothermal mapping enables the functional assessment of a particular site before permanent ablation. In this way, the targeted tissue may be confirmed as safe for ablation. This is useful in high risk ablation, for example, nex to the His bundle or the compact AV node. In the last decade, several studies have been addressed to AV-nodal reentry tachycardia (AVNRT) cryoablation. Current experiences indicate that cryoablation for AV-nodal reentry tachycardia is effective and safe. However, its wide use seems to be somewhat limited by a slightly lower efficacy when compared to radiofrequency. Further studies evaluating long-term success of cryothermal ablation versus radiofrequency are warranted. However, for high-risk ablations, cryoenergy is very helpful and should be systematically used. This article is a review of acute and long-term effects of cryoablation in patients suffering of AV-nodal reentry tachycardia episodes.

Catheter cryoablation of atrio-ventricular nodal reentrant tachycardia. A clinical review / Crioablación con catéter de la taquicardia por reentrada intranodal. Una revisión clínica

Cryoablation is a new method in interventional cardiac electrophysiology for percutaneous catheter ablation of cardiac arrhythmias. Cryothermal mapping enables the functional assessment of a particular site before permanent ablation. In this way, the targeted tissue may be confirmed as safe for ablation. This is useful in high-risk ablation, for example, next to the His bundle or the compact AV node. In the last decade, several studies have been addressed to AV-nodal reentry tachycardia (AVNRT) cryoablation. Current experiences indicate that cryoablation for AV-nodal reentry tachycardia is effective and safe. However, its wide use seems to be somewhat limited by a slightly lower efficacy when compared to radiofrequency. Further studies evaluating long-term success of cryothermal ablation versus radiofrequency are warranted. However, for high-risk ablations, cryoenergy is very helpful and should be systematically used. This article is a review of acute and long-term effects of cryoablation in patients suffering of AV-nodal reentry tachycardia episodes.

La crioablación es un nuevo método en la electrofisiología cardiaca intervensionista para la ablación percutánea de las arritmias cardiacas. El mapeo criotérmico permite la evaluación funcional de un sitio en particular antes de la ablación permanente; de esta manera, el tejido blanco puede confirmarse como seguro para el procedimiento. Esto es útil en la ablación de alto riesgo, por ejemplo, cerca del haz de His o del nodo AV compacto. En la última década, varios estudios se han orientado a la crioablación para la taquicardia de reentrada del nodo AV (TRNAV). Las experiencias actuales indican que la crioablación de la taquicardia de reentrada del nodo AV es efectiva y segura. Sin embargo, la apertura para ampliar su uso está parcialmente limitada por su eficacia ligeramente menor al compararla con el empleo de la radiofrecuencia. Se justifican ensayos clínicos futuros con objeto de evaluar el éxito a largo plazo de la ablación criotérmica en comparación con la radiofrecuencia. Para las ablaciones de alto riesgo, la crioenergía es muy útil y debería ser usada sistemáticamente. Este artículo consiste en una revisión sobre los efectos inmediatos y a largo plazo de la crioablación en pacientes que presentan episodios de taquicardia por reentrada del nodo AV.

Radiofrequency ablation of coronary sinus-dependent atrial flutter guided by fractionated mid-diastolic coronary sinus potentials.

BACKGROUND: The efficacy of radiofrequency (RF) ablation of an uncommon coronary sinus (CS)-dependent atrial flutter (AFL) was evaluated using conventional electrophysiological criteria in a highly selected subset of patients with typical and atypical AFL. METHODS: Fourteen patients with atrial flutter (11 males, mean age 69 ± 9 years) without previous right or left atrial RF ablation were included. Heart disease was present in eight patients. Baseline ECG suggested typical AFL in 12 patients and atypical AFL in two. Mean AFL cycle length was 324 ± 64 ms at the time of RF ablation in the CS. Lateral right atrium activation was counterclockwise (CCW) in 13 patients and clockwise in one. CS activation was CCW in all. Criteria for CS ablation included the presence of CS mid-diastolic fractionated atrial potentials (APs) associated with concealed entrainment with a postpacing interval within 20 ms. Success was defined as termination of AFL and subsequent noninducibility. RESULTS: The initial target for ablation was the cavotricuspid isthmus (CTI) in 11 patients and the CS with further CTI ablation in three. AP duration at the CS target site was 122 ± 33 ms, spanning 40 ± 12% of the AFL cycle length. CS ablation site was located 1-4 cm from the CS ostium. Ablation was successful in all patients. Mean time to AFL termination during CS ablation was 39 ± 52 s (<20 s in eight patients). No recurrence of ablated arrhythmia occurred during a follow-up of 18 ± 8 months. CONCLUSIONS: The CS musculature is a critical part of some AFL circuits in patients with typical and atypical AFL. AFL can be terminated in patients with CS or CTI/CS AFL reentrant circuits by targeting CS mid-diastolic fragmented APs.

A case of inappropriate sinus tachycardia after atrio-ventricular nodal reentrant tachycardia cryoablation successfully treated by ivabradine.

We illustrate a case of persistent inappropriate sinus tachycardia after slow pathway atrio-ventricular (AV) nodal reentrant tachycardia cryoablation, and inadvertent fast pathway lesion with residual first-degree AV block in a 72-year-old man with a small Koch's triangle. At the end of the cryoprocedure, the patient presented with sinus tachycardia 100 b.p.m., while PR was 300 ms. An accelerated sinus rhythm and a PR prolongation persisted over time. The patient was successfully treated with ivabradine with no effect on atrioventricular node conduction.

Effects of inadvertent atrioventricular block on clinical outcomes during cryoablation of the slow pathway in the treatment of atrioventricular nodal re-entrant tachycardia.

AIMS: The study aimed at evaluating the long-term effects of transient atrioventricular (AV) block on clinical outcomes during atrioventricular nodal re-entrant tachycardia (AVNRT) cryoablation. METHODS AND RESULTS: In 150 consecutive patients (39 +/- 14 years, ineffective anti-arrhythmic drugs 1.9 +/- 1.3), slow-pathway cryoablation for AVNRT was performed. A 7 Fr 6 mm-tip cryocatheter was used. After successful cryomapping (-30 degrees C), defined as jump abolition or AV nodal refractory period prolongation, cryoablation (-80 degrees C for 4 min) was applied if no AV block occurred. Atrioventricular nodal re-entrant tachycardia inducibility was checked after 30 min. Acute success (AVNRT non-inducibility) was achieved in 142 patients (95%). Overall, after a follow-up of 18 +/- 10 months, 118 of 150 patients (79%) were recurrence-free (including 2 patients for whom the procedure was unsuccessful). Among successful procedures, 116 of 142 (82%) patients were recurrence-free. During cryoablation, inadvertent transient AV block of varying degrees occurred in 34 patients (22.7%), namely, increased PR in 17 patients and a 2nd-3rd AV block in the remaining 17. In 24 patients, AV block occurred at the last effective site (increased PR in 13 patients and a 2nd-3rd AV block in 11). In the study population as a whole, univariate predictors of recurrence in the follow-up were AVNRT inducibility (P < 0.001), increased PR at the last effective site (P < 0.001), residual jump (P < 0.02), and small Koch's triangle (X-ray distance < 11 mm between the His and coronary sinus ostium catheters; P < 0.02). Atrioventricular nodal re-entrant tachycardia inducibility (P < 0.03), increased PR (P < 0.01), and small Koch's triangle (P< 0.04) were independently significant. For attempts at the last effective site, 3 groups of patients were compared: 13 patients with increased PR duration (Group A), 11 with a 2nd-3rd AV block (Group B), and 126 without AV block (Group C). Cryo-application time was 277 +/- 203 s in Group A, 75 +/- 87 s in Group B, and 253 +/- 135 s in Group C (A vs. B, P < 0.01; B vs. C, P < 0.001; and C vs. A, P= NS). There was no statistical difference among groups in the atriogram/ventriculogram amplitude ratio at the site of the last attempt, unsuccessful acute procedure, small Koch's triangle, and residual jump. Actuarial incidence of recurrence-free status at 12 months was 38% in A, 82% in B, and 82% in C (A vs. B, P < 0.05; B vs. C, P = NS; and C vs. A, P < 0.001). CONCLUSION: All AV blocks occurring during cryoablation were transient, confirming the safety of this method. An increased PR duration at the last effective site is associated with a higher recurrence rate, whereas a 2nd-3rd degree AV block has a recurrence rate similar to that of patients without AV block despite a shorter cryo-application time at the last site.

Effective cryoablation of a lateral accessory pathway within the distal coronary sinus.

Limited information is available on the efficacy of cryoablation in the coronary venous system in humans. A patient with a lateral accessory pathway was referred to our center after several unsuccessful endocardial and epicardial (within the coronary sinus) attempts using standard radiofrequency energy. Ablation was subsequently performed successfully by applying cryoenergy distally into the coronary sinus, using a temperature of -50 degrees C and a freezing application time of 45 s. There were no complications. Angiography of the left coronary circumflex artery and coronary venous system was performed at 12 months follow-up using cardiac multislice computed tomography, and no coronary stenosis or anatomic anomaly was found. Neither pre-excitation or any arrhythmia recurred during follow-up. This experience suggests that ablating in the distal coronary sinus can be safely performed using cryoenergy.

Fulguración de un foco extrasistólico ventricular / Catheter ablation of an extrasystolic ventricular focus

Se presenta un caso de extrasístoles ventriculares sintomáticas refractarias a antiarrítmicos, con morfología QRS de bloqueo de rama derecha y desviación axial izquierda en una mujer de 68 años sin cardiopatía estructural. El mapeo endocárdiaco del foco extrasistólico se localizó en la región meso-inferoapical del septum ventricular izquierdo sugiriendo un origen en la red de Purkinje de la subdivisión posterior izquierda. La ablación transcatéter con energía de corriente directa eliminó las extrasístoles, sin complicaciones del procedimiento y la paciente permaneció asintomática durante el seguimiento a 3 meses

Ablación trans-cateter de vías accesorias atrioventriculares: resultados inmediatos y seguimiento a largo plazo / Catheter ablation of accesory atrioventricular pathways. Immediate results and long term follow-up

Presentamos los resultados inmediatos y a largo plazo, de la serie inicial de pacientes con vías accesorias atrioventriculares, tratados con radiofrecuencia. El procedimiento inicial comprendía, choques de corriente directa inmediatos, siempre que el primer método fracasara. La tasa de éxito inmediato fue similar, tanto para la radiofrecuencia, 75 por ciento (17/22 vías), como cuando se asociaron ambos métodos, 80 por ciento (8/10 vías). Sin embargo, sólo en éstos últimos, se observó recurrencia temprana (6/10 vías). Durante el periodo de seguimiento de 18 a 25 meses, del grupo de pacientes con recurrencia, sólo en uno se observó la desaparición espontánea de la onda delta inicial, y cuatro más, requirieron de dos a tres sesiones para una ablación exitosa. Con ambos métodos, se logró eliminar permanentemente la activación anómala en 20/22 casos (91 por ciento), siendo todos los sujetos asintomáticos y sin tratamiento farmacológico. En cada método empleado, se identificó una complicación mayor, sin defunciones. Por su mayor tasa de éxito, manenores requerimientos técnicos y sus implicaciones económicas, la radiofrecuencia goza de mayor validación en el tratamiento de éstos pacientes. En nuestra institución, el uso de la corriente directa sigue siendo viable, si el comportamiento clínico de la taquiarritmia impide nuevas sesiones con radiofrecuencia sola. Los cambios temporales, físicos y mecánicos, que ésta produce en el tejido cardiaco, interfieren con una ablación certera si se aplica a continuación el método de corriente directa.

Ablación con radiofrecuencia en taquicardia ventricular: experiencia inicial y evaluación de sus limitaciones / Radiofrequency catheter ablation in ventricular tachycardia

El propósito de este reporte es señalar la experiencia clínica inicial con energía de radiofrecuencia en 21 casos consecutivos de taquicardia ventricular de diversa etiología y evaluar las causas que juegan un papel en sus limitaciones. Los resultados muestran un éxito limitado: eficacia clínica global del 43 por ciento, no obstante su alta efectividad en un subgrupo específico de casos. En los resultados están implicados factores como: el substrato y mecanismo electrofisiológico de la taquicardia, los criterios para localizar la zona crítica necesaria para el mantenimiento de la arritmia y las características biofísicas de la corriente de radiofrecuencia. Su utilidad es manifiesta en taquicardias ventriculares en corazón estructuralmente sano y su éxito es limitado en casos con cardiopatía estructural. Se espera que el avance tecnológico, el mejor entendimiento del mecanismo subyacente y las características del sitio blanco mejores los resultados de la ablación con radiofrecuencia en taquicardias ventriculares.

Radiofrecuencia y eliminación de vías accesorias atrio-ventriculares: factores relacionados con ablación exitosa trans-catéter / Radiofrequency energy and ablation of atrioventricular accessory pathways: factors related with catheter successful ablation

La ablación de vías accesorias altrioventriculares por medio de radiofrecuencia ha sido recientemente introducida en el tratamiento de pacientes con síndrome de Wolff-Parkinson-White, por lo que diversos parámetros relacionados con su efectividad fueron analizados. Tras la revisión retrospectiva de los primeros 21 pacientes sometidos a este tratamiento, se logró eliminar la vía accesoria en el 73 por ciento de los casos. Encontramos únicamente los intervalos de activación ventricular con relación al inicio de la onda delta del ECG de superficie y la activación auricular retrógrada más temprana, como estadísticamente significativos para ablación exitosa (P > 0.05 en ambos). No así para otros parámetros seleccionados para identificar los sitios de inserción atrial o ventricular de las vías accesorias, utilizados convencionalmente. En un paciente se colocó marcapasos definitivos por la ablación accidental del nodo atri-ventricular, con vía accesoria de localización septal; ningún paciente falleció. Concluimos que esta alternativa terpéutica en pacientes con vías accesorias y taquiarritmias sintomáticas, ofrece una solución eficaz, con alto porcentaje de éxitos y un mínimo de riesgo, y en los que diversas pruebas de estimulación endocárdica y criterios obtenidos a partir de una cartografía detallada del sitio a tratar, deben considerarse a fin de lograr la eliminación efectiva de vías accesorias