Ventricular Intramyocardial Navigation for Tachycardia Ablation Guided by Electrograms (VINTAGE): Deep Ablation in Inaccessible Targets.

BACKGROUND: Deep intramural ventricular tachycardia substrate targets are difficult to access, map, and ablate from endocardial and epicardial surfaces, resulting in high recurrence rates. OBJECTIVES: In this study, the authors introduce a novel approach called ventricular intramyocardial navigation for tachycardia ablation guided by electrograms (VINTAGE) to access and ablate anatomically challenging ventricular tachycardia from within the myocardium. METHODS: Guidewire/microcatheter combinations were navigated deep throughout the extravascular myocardium, accessed directly from the right ventricle cavity, in Yorkshire swine (6 naive, 1 infarcted). Devices were steered to various intramyocardial targets including the left ventricle summit, guided by fluoroscopy, unipolar electrograms, and/or electroanatomic mapping. Radiofrequency ablations were performed to characterize ablation parameters and reproducibility. Intramyocardial saline irrigation began 1 minute before ablation and continued throughout. Lesions were analyzed on cardiac magnetic resonance and necropsy. RESULTS: VINTAGE was feasible in all animals within naive and infarcted myocardium. Forty-three lesions were created, using various guidewires and power settings. Forty-one (95%) lesions were detected on cardiac magnetic resonance and 38 (88%) on necropsy; all undetected lesions resulted from intentionally subtherapeutic ablation energy (10 W). Larger-diameter guidewires yielded larger size lesions. Lesion volumes on necropsy were significantly larger at 20 W than 10 W (178 mm3 [Q1-Q3: 104-382 mm3] vs 49 mm3 [Q1-Q3: 35-93 mm3]; P = 0.02). Higher power (30 W) did not create larger lesions. Median impedance dropped with preablation irrigation by 12 Ω (Q1-Q3: 8-17 Ω), followed by a further 15-Ω (Q1-Q3: 11-19 Ω) drop during ablation. Intramyocardial navigation, ablation, and irrigation were not associated with any complications. CONCLUSIONS: VINTAGE was safe and effective at creating intramural ablation lesions in targets traditionally considered inaccessible from the endocardium and epicardium, both naive and infarcted. Intramyocardial guidewire irrigation and ablation at 20 W creates reproducibly large intramural lesions.

Bipolar ablation's unique paradigm: Duration and power as respectively distinct primary determinants of transmurality and steam pop formation.

BACKGROUND: Bipolar radiofrequency (RF) ablation strategies are increasingly used, mainly to target deep myocardial reentrant circuits responsible for ventricular tachycardia that cannot be extinguished with traditional unipolar RF ablation. Because this strategy is novel, factors that affect lesion geometry and steam pop formation require further investigation. OBJECTIVE: To assess the effect of contact force, power, and time on the resulting lesion geometry and the risk of steam pop formation during bipolar RF ablation of thick myocardial tissue. METHODS: A custom ex vivo bipolar ablation model was used to assess lesion formation. A combination of parallel and perpendicular configurations of ablation catheters was used to create lesions by varying force (20g, 30g, or 40g), power (30 or 40 W), and time (20, 30, 45, or 60 seconds). Lesion dimensions and the incidence of steam pops were recorded and then analyzed with binary logistic regression and multiple linear regression. RESULTS: In bipolar ablation, lesion transmurality was most affected by the amount of time RF energy was applied. Durations longer than 20 seconds resulted in lesions deeper than half the tissue thickness. Steam pop formation was more frequent in thinner tissue, at longer ablation times, and at higher powers. CONCLUSION: The parameters assessed in this ex vivo model could be used as guidelines for future in vivo work and clinical evaluation of interventricular septal bipolar ablation.

Mapeo y ablación exitosa, desde el interior de la vena cardíaca magna, de extrasístoles ventriculares originados en el techo (summit) del ventrículo izquierdo / Mapping and successful ablation, from within the great cardiac vein, of premature ventricular contractions originating from the summit of the left ventricle

RESUMEN Se presenta el caso de una paciente de 43 años, con antecedentes de salud aparente, hasta varias semanas previas a su ingreso, cuando comenzó a presentar síncopes precedidos de palpitaciones. Se realizó estudio electrofisiológico y se demostró precocidad en la porción distal del electrodo de registro de seno coronario, que corresponde a la vena cardíaca magna (interventricular anterior) y techo (summit) del ventrículo izquierdo. A pesar del excelente registro precoz se estudiaron estructuras vecinas como el tracto de salida del ventrículo izquierdo en la cúspide coronaria izquierda, aquí el mapeo eléctrico (pace mapping) no fue concordante total. En el sitio de la precocidad obtenida dentro del sistema venoso cardíaco se realizó mapeo concordante 100%, con una precocidad del catéter de ablación de -30 milisegundos. Se decidió ablación con incrementos progresivos de temperatura y potencia con corte de impedancia (termomapping) y se logró el éxito de la ablación sin reproducibilidad de la arritmia y excelente evolución posterior.

ABSTRACT The case of a 43-year-old female patient is presented, with an apparent history of good health, up to several weeks prior to admission, when she began to present syncopes preceded by palpitations. An electrophysiological study was performed and prematurity in the distal portion of the coronary sinus recording electrode was demonstrated, which corresponds to the great cardiac vein (anterior interventricular vein) and summit of the left ventricle. Despite the excellent early registration, neighboring structures were studied, such as the left ventricular outflow tract in the left coronary cusp, here the pace mapping was not totally concordant. At the site of the precocity obtained within the cardiac venous system, a 100% concordant mapping was achieved, with an ablation catheter's precocity of -30 milliseconds. The ablation was decided with progressive increases in temperature and power with thermomapping and the success of the ablation was achieved without reproducibility of the arrhythmia and excellent subsequent evolution.

Resultados del estudio electrofisiológico y ablación en niños de hasta 13 años con técnica mínimamente invasiva

El estudio electrofisiológico (EEF) y la ablación en niños son eficaces y están internacionalmente bien pautados. Clásicamente se utilizan tres a cinco accesos vasculares y catéteres endovasculares (CEVs). Propusimos un protocolo simplificado para reducir la cantidad y con ello las complicaciones. Quisimos evaluar los resultados obtenidos. Material y método: realizamos un estudio descriptivo, prospectivo, longitudinal, de 120 pacientes consecutivos de hasta 13 años, sin cardiopatía estructural. El protocolo se basa en utilizar un registro esofágico (RIE) cuando es de utilidad, tener la imagen radiológica en pantalla de la posición del His e ir moviendo un CEV a la posición necesaria cada momento. Resultados: la edad osciló entre 7 meses y 13 años (media=9,5 años) y 72 (62%) eran varones. En 101 (84%) se intentó una ablación y en 19 (16%) EEF. El 70% de las ablaciones fueron por una vía accesoria, 25% por una reentrada nodal y 5% otras causas. El tiempo total de procedimiento fue 104 ± 55 minutos. En 58 niños se intentó RIE y en 57 se logró. El 42% de las ablaciones se hicieron con un solo acceso y 94% con uno o dos CEVs. En seis casos complejos se requirieron tres CEVs y en ninguno, cuatro. Hubo 15 que requirieron más de dos accesos. La ablación fue efectiva en 94%, y seguidos 51±22 meses hubo 6 (6%) recurrencias. Un paciente hizo una pericarditis, no hubo complicaciones vasculares, eléctricas ni otras. Conclusiones: con este protocolo se obtuvieron resultados similares a las series convencionales, con un número muy bajo de accesos, catéteres y complicaciones.

Summary: The electrophysiology study (EPS) and ablation procedure in children are effective and internationally well-defined techniques. They typically use 3 to 5 vascular accesses and endovascular catheters (EVC). We proposed a simplified protocol to reduce these numbers and thus, reduce complications. The study aimed to evaluate the results obtained. Method: we performed a descriptive, prospective, longitudinal study over 120 consecutive patients up to 13 years of age, with no structural heart disease. The protocol consists in using an esophageal record (IER) when it is useful, having the radiological image of its position on the screen and in continuing to move an EVC to the required position at each time. Results: age ranged between 7 months and 13 years (mean = 9.5) and 72 (62%) children were male. In 101 (84%) an ablation was attempted and in 19 (16%) EPS. 70% of the ablations were done for accessory pathways, 25% for nodal reentry tachycardia and 5% others causes. The total time of the procedure was 104 ± 55 minutes. In 58 children an IAR was attempted and in 57 it was achieved. In 42% of cases the ablation was made with 1 single access and 94% with 1 or 2 EVCs. In 6 complex cases 3 EVCs were required and 4 in none. There were 15 cases that required >2 accesses. The ablation was effective in 94%. During 51 ± 22 months of follow-up there were 6 (6%) recurrences. One patient had pericarditis, there were no vascular, electrical, or other complications. Conclusions: with this protocol the results are similar to the conventional series, using a very low number of accesses, catheters and complications rate.

O estudo eletrofisiológico (EPS) e a ablação em crianças são procedimentos eficazes e internacionalmente bem estabelecidos. Tipicamente utilizam-se 3 a 5 acessos vasculares e cateteres endovasculares (CEVs). Propusemos um protocolo simplificado para reduzir a quantidade e com isso as complicações com o fim de avaliar os resultados obtidos. Métodos: realizou-se um estudo longitudinal descritivo, prospectivo, de 120 pacientes consecutivos com até 13 anos de idade, sem cardiopatia estrutural. O protocolo consiste na utilizacao dum registro esofágico (EIR) quando resultar útil, uma imagem radiológica na tela que mostra posição de His e a movimentacao do CEV para a posição necessária a cada momento. Resultados: a idade variou de 7 meses a 13 anos (média = 9,5 anos). 72 (62%) dos pacientes eram do sexo masculino. 101 (84%) pacientes receberam uma ablação e 19 (16%) o FES. 70% das ablações foram por via acessória, 25% por reentrada nodal e 5% por outras causas. O tempo total do procedimento foi de 104 ± 55 minutos. O RIE se tentou em 58 crianças e se conseguiu em 57. 42% das ablações foram feitas com 1 acesso único e 94% com 1 ou 2 CEVs. Em 6 casos complexos, foram necessários 3 CEVs e em nenhum caso foram necessários 4. 15 casos necessitaram de mais de 2 acessos. A ablação foi eficaz em 94% dos casos e, após do seguimento de 51 ± 22 meses, houve 6 (6%) recorrências. Um paciente apresentou pericardite, más sem complicações vasculares, elétricas ou de outro tipo. Conclusões: obtivemos resultados semelhantes com este protocolo para as séries convencionais, com um número muito baixo de acessos, cateteres ou complicações.

Intra-His bundle block in 2:1 atrioventricular block.

Intra-hisian atrioventricular (AV) block is not a common phenomenon, but it is important for the development of advanced or complete AV block. We observed a 77-year-old female patient with the 2:1 AV block due to an intra-hisian block. In this case we tried to detect the block site, but an alternating pattern of the AH conduction was noted on the His-electrogram in the electrophysiological study (EPS). The cause of the confusing finding might have been the instability of the catheter to record a His potential. We could detect a splitting of the His-electrogram with an intra-hisian block after minimal manipulation of the catheter. The authors' observations suggest that catheter stability is important for a precise recording in the EPS and radiofrequency catheter ablation procedure.