Comportamiento del tiempo de conducción retrógrada al momento de la inducción de las taquicardias supraventriculares y su rol en el diagnóstico diferencial / Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

RESUMEN Antecedentes : El diagnóstico diferencial entre la taquicardia reentrante ortodrómica (TRO) y la taquicardia por reentrada nodal atípica (TRNa) puede ser dificultoso. Nuestra hipótesis es que las TRNa tienen más variabilidad en el tiempo de con ducción retrógrada al comienzo de la taquicardia que las TRO. Nuestros objetivos fueron evaluar la variabilidad en el tiempo de conducción retrógrada al inicio de la taquicardia en TRNa y TRO, y proponer una nueva herramienta diagnóstica para diferenciar estas dos arritmias. Métodos : Se midió el intervalo ventrículo-auricular (VA) de los primeros latidos tras la inducción de la taquicardia, hasta su estabilización. La diferencia entre el intervalo VA máximo y el mínimo se definió como delta VA (ΔVA). También contamos el número de latidos necesarios para que se estabilice el intervalo VA. Se excluyeron las taquicardias auriculares. Resultados : Se incluyeron 101 pacientes. Se diagnosticó TRO en 64 pacientes y TRNa en 37. El ΔVA fue 0 (rango intercuartílico, RIC, 0-5) milisegundos (ms) en la TRO frente a 40 (21-55) ms en la TRNa (p < 0,001). El intervalo VA se estabilizó significativamente antes en la TRO (1,5 [1-3] latidos) que en la TRNa (5 [4-7] latidos; p < 0,001). Un ΔVA < 10 ms diagnosticó TRO con 100% de sensibilidad, especificidad y valores predictivos positivo y negativo. La estabilización del intervalo VA en menos de 3 latidos predijo TRO con buena precisión diagnóstica. Los resultados fueron similares considerando sólo vías accesorias septales. Las TRN típicas tuvieron una variación intermedia. Conclusión : Un ΔVA < 10 ms es un criterio simple, que distingue con precisión la TRO de la TRNa, independientemente de la localización de la vía accesoria.

ABSTRACT Background : Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachy cardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives : The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods : The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results : In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p <0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p<0.001). A ΔVA <10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion : Presence of DVA <10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Ablación de reentrada nodal en vena cava superior izquierda persistente y ausencia de vena cava superior derecha / Nodal re-entry in patient with persistent left superior vena cava and absent right superior vena cava

Resumen La taquicardia por reentrada nodal es la arritmia más frecuente entre las taquicardias supraventriculares paroxísticas; la variedad lenta-rápida es la más común. En muchos casos la ablación de la vía lenta es el tratamiento definitivo y puede llegar a tener alta tasa de éxito y baja frecuencia de complicaciones. La presencia de una vena cava superior izquierda y la ausencia de vena cava superior derecha con drenaje venoso sistémico superior al seno coronario es una malformación congénita poco frecuente, la cual genera alteraciones anatómicas que dificultan el abordaje tradicional para la ablación de esta arritmia. Se presenta el caso de una paciente con esta condición en la que fue exitosa la ablación mediante ecocardiografía intracardiaca y reconstrucción tridimensional.

Abstract Nodal re-entrant tachycardia is the most common arrhythmia among the paroxysmal atrioventricular tachycardias, with the slow-fast variant being the most common. In many cases, the ablation of the slow pathway is the definitive treatment in many cases, often with a high rate of success and low frequency of complications. The presence of a left superior vena cava and the absence of a right superior vena cava with systematic venous drainage above the coronary sinus is a rare congenital malformation that leads to anatomical anomalies. These make it difficult to use the traditional approach for the ablation of this arrhythmia. The case is presented of a patient with this condition in which the ablation was successful using intracardiac echocardiography and three-dimensional reconstruction.

Duración de la onda P en las 12 derivaciones del electrocardiograma y su relación con el tiempo de conducción interauricular en pacientes con taquicardias paroxísticas supraventriculares / P wave duration in the 12 leads of the electrocardiogram and its relationship with interatrial conduction time in patients with paroxysmal supraventricular tachycardias

RESUMEN Introducción: Existen algunos estudios que relacionan parámetros de la onda P con diferentes tiempos de conducción auricular, pero no se han realizado teniendo en cuenta a cada derivación del electrocardiograma. Objetivo: Determinar la duración de la onda P (Pdur) en las 12 derivaciones y relacionarlas con el tiempo de conducción interauricular. Método: Estudio de corte transversal en 153 pacientes adultos con diagnóstico confirmado de taquicardia por reentrada intranodal (TRIN) o vías accesorias mediante estudio electrofisiológico invasivo. Resultados: Al comparar la Pdur entre sustratos arrítmicos por cada derivación, no existieron diferencias significativas, excepto en V6. En las derivaciones DII, DIII, aVR, aVF, V1 y de V3-V6 la Pdur se correlacionó con el tiempo de conducción interauricular en ambos sustratos arrítmicos. En el análisis multivariado, la Pdur constituyó un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil, en las derivaciones de cara inferior y en V3, V5 y V6. Se observaron altos valores del área bajo la curva de la Característica Operativa del Receptor en las derivaciones DII (0,950; p<0,001), DIII (0,850; p<0,001) y V5 (0,891; p<0,001). Conclusiones: No existen diferencias por derivación en la Pdur al comparar casos con TRIN y vías accesorias, excepto en V6. La mayoría de las derivaciones se correlacionaron con el tiempo de conducción interauricular. La Pdur fue un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil. La derivación DII presenta la mayor capacidad discriminativa para encontrar valores prolongados del tiempo de conducción interauricular.

ABSTRACT Introduction: Although some studies relate P wave parameters to different atrial conduction times, they do not consider each electrocardiogram lead separately. Objective: To determine the duration of P wave (Pdur) in the 12 leads of the electrocardiogram and relate it to the interatrial conduction time. Method: We conducted a cross-sectional study in 153 adult patients with confirmed diagnosis of atrioventricular nodal reentry tachycardia (AVNRT) or accessory pathways by invasive electrophysiological study. Results: When comparing the Pdur between arrhythmic substrates by each lead, no significant differences were found, except for V6. In leads II, III, aVR, aVF, V1 and V3-V6, Pdur was correlated with the interatrial conduction time in both arrhythmic substrates. In our multivariate analysis, the Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile in inferior wall leads and in V3, V5 and V6. High values of the area under the receiver operating characteristic curve were observed in II (0.950; p<0.001), III (0.850; p<0.001) and V5 (0.891; p<0.001) leads. Conclusions: The Pdur showed no difference by leads when comparing cases with AVNRT and accessory pathways, except for V6. Most of the leads were correlated with the interatrial conduction time; Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile. Lead II has the greatest discriminatory ability to find prolonged values of interatrial conduction time.

Resultado del tratamiento en pacientes sometidos a ablación percutánea por arritmias supraventriculares en la ciudad de Cuenca, periodo abril 2013- julio 2018 / Treatment outcome of percutaneous ablation in patients with supraventricular arrhythmias in Cuenca, April 2013- July 2018

INTRODUCCIÓN: Las taquicardias supraventriculares son comunes en la práctica clínica, a pesar de tener buen pronóstico, puede afectar significativamente la calidad de vida de los pacientes. El tratamiento médico no da como resultado la ausencia total de la arritmia, por lo que la terapia por ablación se ha convertido en el tratamiento de elección en muchos de los casos por su alto índice de éxito brindando una solución definitiva. El objetivo de este estudio es determinar la frecuencia de presentación de las principales taquicardias supraventriculares, distribuidas por edad y sexo, la frecuencia de éxito de la ablación percutánea y los factores relacionados con el mismo y la frecuencia de las complicaciones presentadas. MATERIALES Y MÉTODOS: Se realizó un estudio descriptivo transversal y de correlación, que incluyó 156 con diagnóstico de taquicardia supraventricular y ablacionados en los cinco centros hospitalarios en donde se realizó el procedimiento, basándonos en los registros clínicos de los mismos. RESULTADOS: De los 156 pacientes, 51.9% fueron mujeres y 48.1% hombres, con edades comprendidas entre los 10 y 80 años de edad. Las arritmias reportadas fueron taquicardia de reentrada nodal, taquicardia reentrante auriculoventricular y flutter auricular, de estas la más frecuente fue la taquicardia por reentrada auriculoventricular. El éxito global del tratamiento fue del 93.5%, sin reportar complicaciones, los factores relacionados estudiados no presentaron asociación estadísticamente significativa. CONCLUSIÓN: El tratamiento por ablación tuvo un alto porcentaje de éxito y una tasa nula de complicaciones, esto es un indicador tanto de eficacia como seguridad de este procedimiento.(au)

BACKGROUND: Supraventricular tachycardia is commonly diagnosed in clinical practice, despite having a good prognosis, it can significantly affect the patient's life quality. Pharmacological treatment does not result in the total absence of the arrhythmia, which is why ablation therapy has become the treatment of choice, due to its high success rate, and for offering a definitive solution. The aim of this study was to determine the frequency of each supraventricular tachycardia type, according to age and sex, the rate of success of percutaneous ablation and its related factors, and the frequency of complications due to the procedure. METHODS: A cross-sectional, descriptive, correlational study was conducted, including 156 patients diagnosed with supraventricular tachycardia and ablated, from five hospitals where the procedure was performed, based on their clinical records. RESULTS: From the 156 patients in this study, 51.9% were women and 48.1% men, the age ranged between 10 and 80 years. The most commonly reported arrhythmias were nodal reentrant tachycardia, atrioventricular reentrant tachycardia and atrial flutter, being the atrioventricular reentrant tachycardia the most frequent of all. The global success rate was 93.5%, no complications were reported, and none of the studied factors had significant statistical association with the success rate. CONCLUSION: Ablation treatment had a high success rate, with cero complications in this study, demonstrating the efficacy and safety of the procedure.(au)

Relationship between heart rate on atrioventricular node reentrant tachycardia sustaining and slow path position during procedure of slow path modified ablation using three-dimensional mapping system / 中国介入影像与治疗学

Objective: To observe the relationship between heart rate on atrioventricular node reentrant tachycardia (AVNRT) sustaining and slow path position during procedure of slow path modified ablation using three-dimensional mapping system. Methods: Modified ablation of slow pathway under three-dimensional mapping system was performed in 98 patients with slow-fast (S-F) AVNRT confirmed by invasive electrophysiology examination. The successful target (the site of slow-pathway) and standard His bundle were marked using three-dimensional mapping system, and the distance (Distance A) between the successful target and standard His bundle was measured. The relationship between heart rate in AVNRT and Distance A was analyzed. Results: Distance A was successfully obtained in 96 patients, including 64 tachycardia induced without infusion of isoproterenol, the heart rate was (179.77±29.22)bpm and relevant Distance A was (13.56±5.06)mm, also 32 tachycardia induced with infusion of isoproterenol, the heart rate was (174.91±17.41)bpm and relevant Distance A was (12.43±3.70)mm. No obvious correlation between heart rate and slow path position was found among the above 96 patients (rs=0.048, -0.190; P=0.705, 0.298). Conclusion: There was no obvious correlation between patient's heart rate on AVNRT sustaining and slow path position druing the procedure of slow path modified ablation using three-dimensional mapping system.

3D electronic anatomy mapping guided radiofrequency catheter ablation in 95 children with atrioventricular nodal reentrant tachycardia / 中华儿科杂志

Objective@#To investigate the clinical features and evaluate the efficacy of radiofrequency catheter ablation (RFCA) guided by 3D electronic-anatomy mapping system (CARTO3 System) in children with atrioventricular nodal reentrant tachycardia (AVNRT).@*Methods@#This was a retrospective case-controlled study. Data were collected from 95 children with AVNRT who underwent RFCA using CARTO3 System in the first hospital of Tsinghua University from January 2014 to December 2017. The onset age, characteristic of electrophysiology and anatomy feature of Koch triangle were analyzed. The efficacy and safety of ablation and X-ray fluoroscopy were compared with control 135 children with AVNRT who underwent RFCA without using CARTO3 System. The t test or the chi-square test was used for group comparison. Linear regression equation was established for correlation analysis.@*Results@#The onset age of the 95 children (male 55, female 40; the average age (8.0±3.6) years) with AVNRT was (0.2-17.0) years and 23(24.2%) children were less than 3 years old. Electrophysiologic study showed that 84.2% (80 cases) was AVNRT-slow fast (SF), 11.6% (11 cases) AVNRT-slowslow and 4.2%(4 cases) AVNRT-fast slow. The phenomena of atrio-Hisian(AH) jump occurred in 65.3% and the interval of AH jump was (73.0±10.6) ms. The height of Koch triangle (CSo-His) was (22.3±5.8) mm and related with the weight of children (Y=0.171X+ 16.660, r2=0.224, P<0.001).The distance between the successful ablation target and the lowest point of His zone (ABL-His) was (11.7±2.6) mm. And there was no relation with the body weight(Y=-0.005X + 11.650, r2=0.001, P=0.780) and CSo-His (Y=0.072X+9.914, r2=0.030, P=0.171). The acute success rate was 97.9% (93/95) and recurrent rate was 5.4% (5/93) during follow-up. No obvious complication was reported. Compared with control group, the fluoroscopy time ((3.3±2.5) vs. (10.7±5.8) min, t=13.190, P<0.05), radiation dose ((5.4±4.9) vs. (15.5±6.3) mGy, t=13.660, P<0.05), and dose area product (514±445) vs. (2 478±415) mGy·cm2, t=33.850, P<0.05) were decreased significantly.@*Conclusions@#AVNRT-SF was the most common type of AVNRT. AVNRT incidence in infant and toddlers is lower than that in elder children. CSo-His is correlated with the body weight. ABL-His is relatively fixed. There is no correlation between ABL-His and the body weight and also no correlation between ABL-His and CSo-His. RFCA of AVNRT in children using the CARTO3 system is safe, effective and minimizes X-ray fluoroscopy.

Study on the three-dimensional mapping to reduce the X-ray exposure dose of interventional doctors in radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia / 中华劳动卫生职业病杂志

Objective@#To explore the advantage of radiofrequency catheter ablation under the three-dimensional mapping in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT) in reducing the X-ray exposure dose of interventional doctors.@*Methods@#79 patients with AVNRT, in the first hospital of Shanxi Medical University from January 2015 to June 2016, performed to do radiofrequency catheter ablation treatment were selected, and according to the random number method were divided into two-dimensional mapping group and three-dimensional mapping group. The two-dimensional mapping group was mapped the ablation target at the X-ray, while the ablation target was mapped by CARTO 3 system in the three-dimensional mapping group. Compare the X-ray fluoroscopy time, success rate, complications rate and doctor’s X-ray exposure dose between the two groups.@*Results@#Compared with the two-dimensional mapping group, acute success rate and complication rate of the three dimensional mapping group were not statistically significant (P>0.05) , while the X-ray fluoroscopy time and the X-ray dose of the three-dimensional mapping group decreased significantly, the difference was statistically significant (P<0.05) .@*Conclusion@#Three-dimensional mapping can significantly reduce the X-ray irradiation time and interventional doctor’s X-ray exposure dose in radiofrequency catheter ablation of AVNRT patients and the potential hazards of ionizing radiation on the human body.

Radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia in children and adolescents: a single center experience / 소아과

PURPOSE: Atrioventricular nodal reentry tachycardia (AVNRT) is less common in pediatric patients than in adult patients. Thus, data for pediatric AVNRT patients are insufficient. Hence, we aimed to analyze the patient characteristics, treatment, and any recurrences in pediatric AVNRT patients. METHODS: We reviewed the records of 50 pediatric AVNRT patients who had undergone radiofrequency catheter ablation (RFCA) between January 1998 and December 2016 at a single regional center. The patients were aged ≤18 years. RESULTS: Among 190 pediatric patients who underwent RFCA for tachyarrhythmia, 50 (26.3%; mean age, 13.4±2.6 years) were diagnosed as having AVNRT by electrophysiological study. Twenty-five patients (25 of 50, 50%) were male. Twenty patients (20 of 50, 40%) used beta-blockers before RFCA. All patients had no structural heart disease except 1 patient with valvular aortic stenosis and coarctation of the aorta. RFCA was performed using the anatomic approach under fluoroscopic guidance. The most common successfully ablated region was the midseptal region (25 of 50, 50%). Slow pathway (SP) ablation and SP modulation were performed in 43 and 6 patients, respectively. Complication occurred in 1 patient with complete atrioventricular block. During follow-up, 6 patients had recurrence of supraventricular tachycardia, as confirmed by electrocardiography. Among them, 5 underwent successful ablation at the first procedure. In 1 patient, induction failed during the first procedure. CONCLUSION: RFCA is safe and effective in pediatric AVNRT patients. However, further research is needed for establishing the endpoints of ablation in pediatric AVNRT patients and for identifying risk factors by evaluating data on AVNRT recurrence after RFCA.

Taquicardias supraventriculares. Estado del arte / Supraventricular tachycardia. State of the art

Las taquicardias supraventriculares son un grupo de entidades clínicas prevalentes en la población general, pero que afectan con mayor frecuencia a la población adulta; son ritmos rápidos y generalmente regulares en los cuales se encuentra implicada alguna estructura por encima de la bifurcación del haz de His para formación o perpetuación. El diagnóstico de estas entidades requiere un abordaje clínico sistemático, siendo el electrocardiograma de superficie la principal herramienta para su adecuada clasificación. El tratamiento de las taquicardias supraventriculares dependerá del estado hemodinámico del paciente, el cual definirá el requerimiento de terapia eléctrica o tratamiento médico. Se debe hacer una selección adecuada de los pacientes que requieren estudio electrofisiológico y ablación.

Supraventricular tachycardias are a set of clinical entities prevalent in the general population, but it is the adult population the most frequently affected by them. They are fast and usually regular rhythms in which some structures involved over the bundle of His bifurcation for its formation or maintenance are found. The diagnosis of these entities requires a systematic clinical approach being the surface electrocardiogram the main tool for their proper classification. Treatment of supraventricular tachycardias depends on the patient´s hemodynamic status, which will define the need of electrical therapy or medical treatment. An appropriate selection of patients requiring electrophysiological study and ablation should be made.

Spontaneous Transition of Double Tachycardias with Atrial Fusion in a Patient with Wolff-Parkinson-White Syndrome

Among patients with Wolff-Parkinson-White syndrome, atrioventricular reciprocating tachycardia (AVRT) and atrioventricular nodal reentrant tachycardia (AVNRT) can coexist in a single patient. Direct transition of both tachycardias is rare; however, it can occur after premature atrial or ventricular activity if the cycle lengths of the two tachycardias are similar. Furthermore, persistent atrial activation by an accessory pathway (AP) located outside of the AV node during ongoing AVNRT is also rare. This article describes a case of uncommon atrial activation by an AP during AVNRT and gradual transition of the two supraventricular tachycardias without any preceding atrial or ventricular activity in a patient with preexcitation syndrome.

Pitfalls of Atrial Advancement Using a Ventricular Extra-stimulus During Supraventricular Tachycardia

The delivery of single His-refractory ventricular extra-stimulus during supraventricular tachycardia is useful to identify the mechanism of the tachycardia. We present the different responses based on the ventricular extra-stimulus site. Our findings demonstrate that the atrial activation via an accessory pathway was not advanced based on the ventricular pacing site. Therefore, atrioventricular tachycardia could masquerade as atrioventricular nodal reentrant tachycardia.

Fibrilação atrial durante taquicardia por reentrada nodal atrioventricular: achado sugestivo da presença de via superiorcomum nodal / Atrial fibrillation during atrioventricular nodal reentry tachycardia: a suggestive finding favoring the presence of the upper common nodal pathway

Na taquicardia por reentrada nodal atrioventricular, a necessidade do átrio para a manutenção da taquicardia é controverso. Descrevemos um caso de fibrilação atrial ocorrendo durante taquicardia por reentrada nodal atrioventricular sem afetar o ciclo da arritmia, e discutimos as evidências favorecendo a presença de umavia comum superior.

In Atrioventricular Nodal Reentry Tachycardia the requirement of the atrium for the maintenance oftachycardia is controversial. We describe a case of atrial fibrillation that occurred during Atrioventricular Nodal Reentry Tachycardia without affecting the arrhythmia cycle, and discuss the evidences favoring the presence ofan upper common pathway.

Correlation between connexins and atrioventricular node / 心血管康复医学杂志

Atrioventricular node is responsible for conducting impulse from atria to ventricles.Connexin within atri-oventricular junction play a key role in conducting function of atrioventricular junction;because it presents diversi-fied expression,so its conducting junction is diversified in different areas of atrioventricular junction.Knowing ex-pression type of connexins can approximately determine conductive function in atrioventricular junction area.

Effective analysis on cool-tipped catheter ablation of epicardial accessory pathway / 重庆医学

Objective To investigate the efficacy and safety of cool-tipped saline-irrigated catheter ablation of epicardial accesso-ry pathway in the patients after failure of conventional radiofrequency ablation .Methods 30 patients with epicardial accessory path-way after failuer of conventional radiofrequency ablation were included in this study ,among them ,25 cases of the left accessory pathway and 5 cases of the right accessory prathway used the cool-tipped catheter for conducting ablation through the endocardium (ventricular side or atrial side) or coronary sinus .Results All patients achieved success ,no intraoperative and postoperative related complications occurred .Conclusion The cool-tipped saline-irrigated catheter ablation of epicardial accessory pathway is effective and safe in the patients after failure of conventional radiofrequency ablation ,which may improve the success rate of epicardial acces-sory pathway ablation .

Successful Ablation of Resistant Left Lateral Accessory Pathway and Coexisting Atypical Atrioventricular Nodal Reentrant Tachycardia

A 41-year-old male was presented with drug-resistant supraventricular tachycardia. Electrophysiological study confirmed that the supraventricular tachycardia was caused by dual atrioventricular nodal pathways and a left lateral accessory pathway (AP). The left lateral AP was resistant to traditional endocardial ablation, but was successfully eliminated by radiofrequency ablation via the intracoronary sinus approach.

Radiofrequency current catheter ablation combined with multiple X-ray projecting angles in the treatment of atrioventricular nodal reentrant tachycardia patients / 中国医师进修杂志

Objective To investigate the therapy efficiency and complication prevention in patients undergoing radiofrequency current catheter ablation combined with multiple X-ray projecting angles.Methods Two hundred and six atrioventricular nodal reentrant tachycardia (AVNRT) patients were involved in this study. The distance between the tip of His and the ostium of coronary sinus were measured under different X-ray projecting angles respectively, including posterior anterior (PA), right anterior oblique 30° (RAO 30° ) and left anterior oblique 45° (LAO 45° ) in each patient, and mapping was proceeding under the corresponding X-ray projecting angles with the longest distance. The distance between ablating catheter and His was confirmed again before powering by the other two X-ray projecting angles. Results The longest distance between the tip of His and the ostium of coronary sinus were obtained in 66,75 and 65 patients under PA,RAO 30° and LAO 45° respectively(P＞ 0.05 ),and the data were (2.94 ± 0.87), (2.98 ± 0.76)and (2.91 ± 0.52) cm(P＞ 0.05). Transient first or second degree of atrioventricular blocking was observed in 4 cases among 22 high risk patients in which the powering sites were above the medium level of the distance between the tip of His and the ostium of coronary sinus under three kinds of X-ray projecting angles obviously.However,only 1 case was observed in other 184 patients(P＜ 0.01 ). All patients were cured successfully and no permanent atrioventricular blocking occurred. Conclusion Radiofrequency current catheter ablation combined with multiple X-ray projecting angles is helpful to increasing the successful rate and preventing complication in ablating therapy.

Hemodynamic Effects of Simulated Ventricular Tachycardia and Supraventricular Tachycardia in Dogs

BACKGROUND AND OBJECTIVES: Tachycardias have various clinical features according to the heart rate, the left ventricular systolic function, the site of origin and the mechanisms of the tachycardias. The primary purpose of this study was to evaluate the role of the origin site and cycle length on the ventricular tachycardia (VT) hemodynamics. Our secondary purpose was to explore the possible hemodynamic differences between the two common supraventricular tachycardias (SVT). MATERIALS AND METHODS: VT was simulated in 18 dogs that had there chests opened by using ventricular pacing (VP) at 3 different sites: the left ventricular apex (LVA), the right ventricular outflow tract (RVOT), and the right ventricular apex (RVA). The mean arterial pressure (MAP), the mean left atrial pressure (MLAP) and the mean pulmonary artery pressure (MPAP) were monitored during VP. To simulate SVT, the right atrial appendage and the right ventricular basal septum were stimulated at different cycle lengths with different ventriculo-atrial (VA) time intervals in another 11 dogs that had their chests opened. The arterial pressure, the pulmonary capillary wedge pressure and the cardiac output was observed during simulated atrial tachycardia (Group I), AVRT (Group II) and AVNRT (Group III). RESULTS: In the VT study, at the same pacing site as of the VP, the MAP was significantly decreased with the VP, and the deltaMAP was significantly increased as the length of the VP cycle shortened. At the same pacing cycle length of the VP, the deltaMAP was significantly greater at the RVA or RVOT than at the LVA. At the same pacing site of the VP, the MLAP and the deltaMLAP were significantly increased as the VP cycle length shortened. In the SVT study, MAP was highest in Group I and it decreased with the decreasing VA interval, but this was not significant. The systolic arterial pressure was significantly higher in Group II than in Group III. The CO was higher in Group I than in the other two groups, with a significant difference, and the CO decreased with shortening of the VA interval, but this was not significant. CONCLUSION: The above results suggest that in addition to the tachycardia rate, the origin site could be an independent factor of the VT hemodynamics. Episodes of AVRT and AVNRT may have a different hemodynamic impact that probably originates from the different timing of the ventricular and atrial contraction.

Significance of Atrio-Ventricular Block Following Atrio-His Jump in the Diagnosis of Dual Atrioventricular Nodal Physiology with Adenosine Infusion

BACKGROUND AND OBJECTIVES: Atrioventricular block (AVB) is frequently seen following atrio-His (AH) interval lengthening after adenosine injection during sinus rhythm when both the fast and slow pathways are blocked in patients with dual atrioventricular nodal physiology (DAVNP). However, the condition also occurs in patients without DAVNP. Therefore, an AH jump may not indicate DAVNP if AVB is accompanied. The goal of this study was to use a low dose (6-9 mg) of adenosine to determine whether an AH jump truly represents DAVNP when the presence or absence of AVB following the AH jump is taken into consideration. SUBJECTS AND METHODS: This study included 78 patients (male:female=47:31, age 40.0+/-15.7 years, DAVNP group, n=46, control group, n=32). Adenosine (6-9 mg) was administered intravenously during sinus rhythm. The inclusion criteria of DAVNP were either induced AVNRT (n=37:common type, n=35, uncommon, n=2) or identification of AH jump (n=9) during elctrophysiology study (EPS). The control group consisted of patients without evidence of DAVNP and noninducible AVNRT on EPS. In all subjects, the electrophysiologic parameters of the AV nodal properties were tested. In the DAVNP group, intravenous adenosine during sinus rhythm resulted in an AH jump without AVB (8/46, 17.4%), an AH jump followed by AVB (9/46, 19.6%), an AH jump accompanied by induced AVNRT (1/46, 2.1%), or no significant changes in the AH interval (28/46, 60.9%). In the control group, none of the subjects showed an AH jump without AVB, however an AH jump with subsequent AVB was observed in 4 of 32 subjects (12.5%). If the finding of an AH jump without AVB alone was considered as a positive criteria of DAVNP, its specificity (87.5% to 100%) and positive predictive value (81.8% to 100%) increased compared to the criteria defined by an AH jump regardless of the presence or absence of AVB, however, its sensitivity decreased from 39.1% to 19.6%. CONCLUSION: AH jump induced by adenosine injection may not indicate DAVNP if AVB follows.