Right-sided Accessory Pathway Research Articles

Anterograde His bundle activation during right ventricular overdrive pacing in supraventricular tachycardia.

Differentiation between atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular re-entrant tachycardia (AVRT), and atrial tachycardia (AT) is often challenging during electrophysiology studies. This study compared the sensitivity and specificity of identifying anterograde His bundle activation during entrainment with commonly used right ventricular (RV) pacing maneuvers to differentiate between these types of supraventricular tachycardia (SVT). Out of 112 consecutive patients with SVT, 90 (36 males [40%], age 37 ± 16 years) were prospectively studied. After entrainment during RV pacing, atrial response upon cessation of pacing, anterograde His activation during entrainment, stimulus-atrial (SA), ventriculoatrial (VA) intervals, and post-pacing interval minus tachycardia cycle length (PPI-TCL) were determined. Ventricular extrastimulation during tachycardia and para-Hisian pacing were performed. The final diagnosis was AVNRT in 54, AVRT in 33, and AT in 3 patients. Entrainment was achieved in 87(96%) patients. Anterograde His bundle activation predicted AVRT (sensitivity: 62.5%, specificity: 100%). PPI-TCL ≥129ms predicted AVNRT (sensitivity: 83%, specificity: 84%), as did SA-VA value ≥85ms (sensitivity: 91%, specificity: 87%). Atria were advanced during transition zone in 57% of AVRTs. Atrial pre-excitation in response to progressively premature ventricular extrastimuli identified AVRT (sensitivity: 90%, specificity: 85%). Pre-excitation index ≥87ms identified AVNRT (sensitivity: 80%, specificity: 100%). Para-Hisian pacing identified AVRT (sensitivity: 25%, specificity: 100%). RV pacing maneuvers, applied in isolation, can misclassify a significant proportion of SVTs. Identifying anterograde His bundle activation during entrainment can complement other discriminators in differential diagnosis of SVT, with greatest sensitivity in septal and right-sided accessory pathways.

A CASE OF DILATED CARDIOMYOPATHY WITH DYSSYNCHRONY DUE TO WPW

Patients with Wolff-Parkinson-White (WPW) syndrome and a right-sided accessory pathway (AP) have a wide QRS similar to a LBBB or RV pacing which can result in dyssynchrony and a dilated cardiomyopathy. WPW may be treated with catheter ablation (CA). Cardiac resynchronization therapy (CRT) can also

Hazards of ventricular pre-excitation to left ventricular systolic function and ventricular wall motion in children: analysis of 25 cases.

AimThe aim was to attach importance to the hazards of ventricular pre-excitation on left ventricular systolic function and size. METHOD: We analysed the clinical, electrophysiological, and echocardiographic characteristics of the 25 cases with abnormal ventricular wall motion, left ventricular systolic dysfunction, or dilation with co-existing right-sided overt accessary pathways before and after ablation or medication during March 2011 and June 2017. Moreover, we compared the therapy effect between patients with ventricular pre-excitation-induced dilated cardiomyopathy and idiopathic dilated cardiomyopathy without ventricular pre-excitation.ResultAbnormal ventricular wall motion was demonstrated using M-mode echocardiography in 23 cases. The basal segments of the interventricular septum became thin and moved similarly to an aneurysm with typical bulging during end-systole, which was observed in 16 cases. Dilated cardiomyopathy was diagnosed in 14 cases. A total of 23 patients underwent successful ablations and received medications, and the other two patients received only oral medications because of young age. The prognosis of pre-excitation-induced dilated cardiomyopathy is better than idiopathic dilated cardiomyopathy. All the cases with abnormal ventricular wall motion demonstrated recovery of normal left ventricular ejection fraction and decreased left ventricular end-diastolic diameter through ablation. CONCLUSION: Ventricular pre-excitation caused by right-sided accessory pathways may result in abnormal ventricular wall motion, left ventricular systolic dysfunction, dilation, and even dilated cardiomyopathy. In some cases with dilated cardiomyopathy, ventricular pre-excitation may not be the cause of disease but a harmful factor which hampered the recovering of left ventricular systolic function. These conditions are indications for ablation with good prognosis.

Catheter ablation in ASymptomatic PEDiatric patients with ventricular preexcitation: results from the multicenter "CASPED" study.

As there are limited data about the clinical practice of catheter ablation in asymptomatic children and adolescents with ventricular preexcitation on ECG, we performed the multicenter "CASPED" (Catheter ablation in ASymptomatic PEDiatric patients with Ventricular Preexcitation) study. In 182 consecutive children and adolescents aged between 8 and 18years (mean age 12.9 ± 2.6years; 65% male) with asymptomatic ventricular preexcitation, a total of 196 accessory pathways (APs) were targeted. APs were right sided (62%) or left sided (38%). The most common right-sided AP location was the posteroseptal region (38%). Ablation was performed using radiofrequency (RF) energy (93%), cryoablation (4%) or both (3%). Mean procedure time was 137.6 ± 62.0min with a mean fluoroscopy time of 15.6 ± 13.8min. A 3D mapping or catheter localization system was used in 32% of patients. Catheter ablation was acutely successful in 166/182 patients (91.2%). Mortality was 0% and there were no major periprocedural complications. AP recurrence was observed in 14/166 patients (8.4%) during a mean follow-up time of 19.7 ± 8.5months. A second ablation attempt was performed in 20 patients and was successful in 16/20 patients (80%). Overall, long-term success rate was 92.3%. In this retrospective multicenter study, the outcome of catheter ablation for asymptomatic preexcitation in children and adolescents irrespective of antegrade AP conduction properties is summarized. The complication rate was low and success rate was high, the latter mainly depending on pathway location. The promising results of the study may have future impact on the ongoing risk-benefit discussion regarding catheter ablation in the setting of asymptomatic preexcitation in children and adolescents.

An alternative under-valve approach to ablate right-sided accessory pathways

Right-sided accessory pathway (RAP) ablation is sometimes challenging. Our study aimed to demonstrate an alternative ablation approach to RAPs under the tricuspid valve, especially when the conventional ablation attempts at the atrial side failed. Twelve patients with RAPs were enrolled, 8 of whom had previously failed ablation. With the help of a long sheath, the under-valve approach was attempted in 3 patients during tachycardia, in 2 patients during ventricular pacing, and in 7 patients during sinus rhythm. Three-dimensional electroanatomic mapping was performed in 3 patients during their repeat procedures. The acute outcomes of the procedures in all patients were successful. Patients were free of tachycardia or recurrence of accessory pathway conduction during a median follow-up of 12.5 months (range 7-45 months). No complications were found during the procedure or follow-up period. Radiofrequency ablation under the tricuspid valve to eliminate RAPs is feasible because of its stable contact and the accurate ablation of the ventricular insertion site. It provides an alternative approach to tough RAP ablation.

Delta wave notching time is associated with accessory pathway localization in patients with Wolff-Parkinson-White syndrome

Our aim was to investigate the relation between delta wave notching time (DwNt) and accessory pathway location in patients with Wolff-Parkinson-White (WPW) syndrome. The retrospective study included 149 WPW patients who underwent ablation therapy. DwNt was defined as the duration between the initial point of QRS and the notching in the delta wave. DwNt was divided by QRS duration to obtain the delta wave index (Dwi). Patients with left-sided accessory pathway (AP) had significantly higher DwNt (p < 0.001) and Dwi (p = 0.027) values. The R wave voltage in lead I (p = 0.037) and S wave voltage in lead V1 (p = 0.005) values were significantly higher in patients with right-sided AP compared to patients with left-sided AP. When 27ms was taken as the DwNt cut-off value, higher durations determined the left-sided AP location with a sensitivity of 91% and a negative predictive value of 91.4%. Dwi cutoff values ≥ 0.29 were accepted to indicate a left-sided AP location with a sensitivity of 91.2% and a NPV of 91.4%. WPW patients with left-sided AP have longer DwNt values than patients with right-sided AP.

Comparison of the Accuracy of Three Algorithms in Predicting Accessory Pathways among Adult Wolff-Parkinson-White (WPW) Syndrome Patients in our Population

Background: after the introduction of catheter ablation of atrioventricular accessory pathways (APs) in Wolff-Parkinson-White (WPW) syndrome, to facilitate planned ablation and minimize catheter-related injury, predicting the AP was required. Localization of APs can be anywhere around the atrioventricular (AV) annuli, left- or right-sided, or within the septum or a rare possibility of Mahaim fibers. Objective: to compare between three algorithms in their accuracy in predicting the exact site of accessory pathway. Patients and Methods: one hundred patients with manifest pre-excitation who underwent electrophysiological study (EPS) and successful ablation of accessory pathway who were subjected to history taking, complete physical examination stressing on 12-lead of pre-excited electrocardiogram (ECG). Results: the distributions of the accessory pathway with left lateral accessory pathway being the most prevalent (27%) while the postero-lateral being the least prevalent one (2%) and that Right-sided accessory pathway was most frequently predicted by Arruda algorithm in 31% of patients and least frequently predicted by D’Avila in 17% of patients while its actually present in 23% of patients according to the EP study, Left-sided accessory pathway was most frequently predicted by D’Avila (61%) and least frequently predicted by Arruda (49%) whereas it was truly present in 51% of patients according to EP study. Mid and antero-septal accessory pathways were most frequently predicted by Chiang and least frequently predicted by Arruda while it was present in 26% of cases proved by EP study. In all algorithms, 72 % of predictions were correct for Chiang, 81 % for D’Avila, and 71 % for Arruda and the percentage of predictive accuracy of all algorithms did not differ between the algorithms (p=1.000; p=0.076; p=0.064, respectively) The best algorithm for prediction of right-sided and left-sided accessory pathways was D’Avila (p<0.001). The best algorithm that is particularly useful in predicting antero-septal and mid-septal accessory pathways was Chiang (p<0.001). Conclusion: prior knowledge of the AP location allows better planning, faster and safer procedure, as well as decreased exposure to ionizing radiation and unnecessary punctures. In all algorithms, 72% of predictions were correct for Chiang, 81% for D'Avila, and 71% for Arruda and the percentage of predictive accuracy of all algorithms did not differ between the algorithms (p=1.000; p=0.076; p=0.064, respectively). The best algorithm for prediction of right-sided and left-sided accessory pathways was D'Avila (p<0.001). The best algorithm that is particularly useful in predicting anteroseptal and mid-septal accessory pathways was Chiang (p<0.001).

Comparison of the Accuracy of Three Algorithms in Predicting Accessory Pathways among Adult Wolff-Parkinson-White (WPW) Syndrome Patients in our Population

Background: after the introduction of catheter ablation of atrioventricular accessory pathways (APs) in Wolff-Parkinson-White (WPW) syndrome, to facilitate planned ablation and minimize catheter-related injury, predicting the AP was required. Localization of APs can be anywhere around the atrioventricular (AV) annuli, left- or right-sided, or within the septum or a rare possibility of Mahaim fibers. Objective: to compare between three algorithms in their accuracy in predicting the exact site of accessory pathway. Patients and Methods: one hundred patients with manifest pre-excitation who underwent electrophysiological study (EPS) and successful ablation of accessory pathway who were subjected to history taking, complete physical examination stressing on 12-lead of pre-excited electrocardiogram (ECG). Results: the distributions of the accessory pathway with left lateral accessory pathway being the most prevalent (27%) while the postero-lateral being the least prevalent one (2%) and that Right-sided accessory pathway was most frequently predicted by Arruda algorithm in 31% of patients and least frequently predicted by D’Avila in 17% of patients while its actually present in 23% of patients according to the EP study, Left-sided accessory pathway was most frequently predicted by D’Avila (61%) and least frequently predicted by Arruda (49%) whereas it was truly present in 51% of patients according to EP study. Mid and antero-septal accessory pathways were most frequently predicted by Chiang and least frequently predicted by Arruda while it was present in 26% of cases proved by EP study. In all algorithms, 72 % of predictions were correct for Chiang, 81 % for D’Avila, and 71 % for Arruda and the percentage of predictive accuracy of all algorithms did not differ between the algorithms (p=1.000; p=0.076; p=0.064, respectively) The best algorithm for prediction of right-sided and left-sided accessory pathways was D’Avila (p<0.001). The best algorithm that is particularly useful in predicting antero-septal and mid-septal accessory pathways was Chiang (p<0.001). Conclusion: prior knowledge of the AP location allows better planning, faster and safer procedure, as well as decreased exposure to ionizing radiation and unnecessary punctures. In all algorithms, 72% of predictions were correct for Chiang, 81% for D'Avila, and 71% for Arruda and the percentage of predictive accuracy of all algorithms did not differ between the algorithms (p=1.000; p=0.076; p=0.064, respectively). The best algorithm for prediction of right-sided and left-sided accessory pathways was D'Avila (p<0.001). The best algorithm that is particularly useful in predicting anteroseptal and mid-septal accessory pathways was Chiang (p<0.001).

Novel use of a 3-dimensional mapping system in cryoablation of right-sided and septal accessory pathways: playback ablation.

Despite recent advances in the treatment of eliminating accessory pathways (APs), catheter-induced mechanical block (bump) of APs has been reported to result in a less favorable outcome with high primary failure and recurrence rates. The real bump site cannot always be precisely reapproached under fluoroscopy so physicians can perform ablation to a location different from where the mechanical block was encountered. In this paper, we describe this novel use of a 3-dimensional (3D) mapping system (playback ablation) with a case series. The EnSite Velocity system (St. Jude Medical, St. Paul, MN, USA), a 3D mapping system, has a unique function that records the positional information of catheters in a 3D geometric map and the local potential of catheters continuously. This function enables physicians to specify the bump site in a 3D geometric map and apply ablation to the bump site even if the catheter moves away from the bump site. This technique helped us eliminate APs in two patients with bump of APs, and they have been free of preexcitation and arrhythmias without the use of anti-arrhythmic drugs for more than 3months. This technique may contribute to improving long-term success in patients with mechanical block of APs.

Irrigated-tip catheters for radiofrequency ablation of right-sided accessory pathways in adolescents.

Catheter ablation of right-sided accessory pathways (APs) has lower success and higher recurrence rates compared to left-sided substrates. Irrigated-tip catheter (ITC) ablation might offer an advantage in this setting but data about its use in patients below 18 years are scarce. The aim of this study was to compare an ITC approach to conventional catheter ablation. A retrospective analysis of all patients<18 years undergoing radiofrequency ablation (RFA) for right-sided APs from 2004 to 2014 at our institution was performed. Patients either underwent an ITC approach in combination with 3-D mapping (Group 1; n=53) or a conventional non-ITC approach (Group 2; n=52). Study endpoints were acute procedural success, safety, and recurrence rate. A total of 105 mostly adolescent patients (56.2% male; median age 14 years) with 107 right-sided APs were included. The prevailing anatomic AP locations were right posteroseptal (44.9%), right anterior/anterolateral (24.3%), and right lateral (13.1%). Acute success (94.3%vs 94.2%) did not differ between the groups. One major complication (pericardial effusion) occurred in the non-ITC group. Overall, freedom from AP recurrence was 94% at 4 years in the ITC group, and 81% at 4 years in the non-ITC group (P=0.04). The use of ITCs in combination with 3-D mapping system for ablation of right-sided APs in adolescents has a high acute success rate, is safe, and associated with a significantly reduced recurrence rate compared to a non-ITC/conventional approach. It might be considered as alternative approach in this age group.

Limited fluoroscopy catheter ablation of accessory pathways in children

BackgroundLimited fluoroscopy ablation using 3D electro-anatomical system (3DS) has been used for arrhythmias in children, however it is not a common practice. We aimed to facilitate a fluoroscopy limited approach for ablation of accessory pathways (AP) in children. MethodsFollowing electrophysiologic (EP) catheter placement a single dual-plane fluoroscopic image (right anterior oblique-30° and left anterior oblique-60° views) was acquired and the 3DS views were rotated to be a perfect match to the fluoroscopy. Ninety-four consecutive pediatric patients [mean age 11.8±4.1 (4.2–18) years, 61.7% males] with Wolf–Parkinson–White syndrome underwent ablation of an AP. Fifty-seven had manifest AP, 54 had left-sided AP (LSAP) and 40 had right-sided AP (RSAP). ResultsThe acute success rate was 95.7% (90/94), with a recurrence rate of 1.1% (1/90) at a mean follow-up of 13±5.5 (4.4–22.9) months. Mean procedure and fluoroscopy times were 144±45 (55–262)min and 1.8±1.4 (0.1–5.6)min, respectively. Comparison of the first 20 procedures to the next 74 procedures demonstrated an extended procedure time (171±53min vs 135±38min, p<0.005), however the fluoroscopy time, the number of long applications, the time to effect, and the acute success rate were similar. There were no permanent ablation-related complications. ConclusionsA limited fluoroscopy approach for ablation of AP in children using 3DS is easily acquired, adapted, reduces the fluoroscopy time, and has an excellent efficacy and safety profile.

Accessory pathway induced dilated cardiomyopathy

Accessory pathway-induced dilated cardiomyopathy is a new diagnosis proposed recently.Pre-excitation of part of the myocardium may mediate electrical and mechanical dyssynchrony, which will result in decreased left ventricular systolic function and increased diameter of left ventricle in patients with right-sided overt accessory pathways(type B ventricular preexcitation). Its features are listed as follows: (1)Incessant and prolonged tachyarrhythmia never happened.Tachycardiomyopathy and other causes of dilated cardiomyopathy are excluded.(2)Right-sided overt accessory pathways are shown by electrocardiogram.(3)Echocardiography indicates dyssynchronous left ventricle contraction, decreased left ventricular systolic function and increased diameter of left ventricle.Normal interventricular septal motion, recovered left ventricular and reversed left ventricular remodeling can be realized by radiofrequency ablation with a good prognosis.To infant patients, taking anti arrhythmia drugs to inhibit the conduction of the accessory pathway was recommended. Key words: Ventricular pre-excitation; Dilated cardiomyopathy; Dyssynchrony

Cryoablation with an 8‐mm‐Tip Catheter for Right‐Sided Accessory Pathways in Children

Cryoablation is increasingly utilized in children because of its safety profile. Recently, larger catheter tips have been more widely used to improve long-term success rates. The aim of this study was to assess the safety and efficacy of 8-mm-tip catheters for cryoablation of right-sided accessory pathways (APs) in children. Electrophysiological procedures were performed using the EnSite™ system (St. Jude Medical Inc., St. Paul, MN, USA). Between July 2010 and July 2014, 54 patients (mean age: 13.1 ± 3.7 years) underwent cryoablation using an 8-mm-tip catheter. In 18 of 54 (33%) patients where an 8-mm-tip catheter was the first-choice catheter, the success rate was 18 of 18 (100%). There was a history of previous failed attempts or recurrence with radiofrequency ablation and/or 6-mm-tip cryoablation in 36 of 54 (67%) patients. The success rate in these patients was 24 of 36 (67%). No fluoroscopy was used in 34 of 54 procedures. The recurrence rate was six of 42 (14%) during a mean follow-up period of 32 ± 15 months. In one patient, transient atrioventricular block occurred. Cryoablation with an 8-mm-tip catheter for right-sided APs in children who weigh over 40 kg appears to be safe and acutely effective in cases where conventional ablation methods fail and also as a first choice for ablation procedure. However, the recurrence rate still seems to be high.

16-30: Radiofrequency ablation of right-sided accessory pathways in children: how have 3-D mapping systems and cool-tip catheters changed success, fluoroscopy time and recurrence?

Aims: Catheter ablation of right-sided accessory pathways (AP) still presents a challenge with lower success and higher recurrence rates. We evaluated the use of a 3-dimensional mapping (3-D) system in combination with irrigated-tip ablation catheter (ITC) compared to a conventional fluoroscopic/non- irrigated tip catheter approach in patients <18 years undergoing radiofrequency ablation (RFA) for right-sided APs with regard to acute procedural success, fluoroscopy time/dosage, safety and recurrence rate. Methods and results: A retrospective analysis of all patients <18 years undergoing RFA for right-sided APs from May 2004 to December 2014 was performed. In 2010, our approach had changed from conventional fluoroscopy/non- irrigated tip catheters to the use of a 3-D mapping system in combination with irrigated- tip catheter ablation. A total of 105 children (56.2% male) age 4.0–17.9 years (mean 13.4 ± 2.9 years) with 107 right-sided accessory pathways were included in the study. In 15 patients, congenital heart disease was present (Ebstein anomaly n = 8). Preexcitation was overt (n = 75) or concealed (n = 32). AP localization was right free wall (n = 54) or septal (n = 53). The most common AP site was the posteroseptal region (44.9%). Patients were divided into 2 groups. Group 1 included 53 patients (50.5%) undergoing RFA with the use of a 3D mapping system and ITC whereas Group 2 consisted of 52 patients (49.5%) with a conventional fluoroscopic approach/non- irrigated ablation catheter. Study endpoints were acute procedural success rate, fluoroscopy time/dosage, safety and recurrence rate. Radiofrequency catheter ablation was performed acutely successful in 101 of 107 accessory pathways (94.3%). Acute success rates did not differ between Group 1 (94.3%) and Group 2 (94.2%). Procedure time was shorter in the 3-D/ITC Group (mean 129.4 min versus mean 170.9 min; p = 0.001). Fluoroscopy time (mean 12.8 min vs. mean 22.9 min; p = 0.004) and fluoroscopy dose (mean 329.7 cGycm2 vs. mean 756.3 cGycm2 p = 0.009) were also lower in the 3-D/ITC group compared to the conventional group. Overall mortality was 0%. Complications occurred in 5 patients (4.8%) with one major complication in Group 2 (pericardial haemorrhage). Minor vascular complications at the puncture site were observed in 3 patients (2.9%). One patient from Group 2 with a midseptal location pathway developed first-degree atrioventricular block. AP recurrence after an initially successful ablation was observed in 12/101 cases (11.8%). The use of a 3-D system/ITC was associated with a significantly lower AP recurrence rate (6.0% Group 1 vs. 18.4% Group 2; p < 0.05). Conclusion: The use of a 3-D mapping system in combination with irrigated-tip catheter ablation (3-D/ITC) for the ablation of right- sided accessory pathways in children and adolescents is associated with a reduced procedure and fluoroscopy time as well as fluoroscopy dosage. The recurrence rate is significantly lower using 3-D/ITC compared to a conventional approach. The combination of 3-D mapping and irrigated tip catheter ablation might therefore be considered as preferred approach for the ablation of right-sided APs in this age group.

176-29: Number of beats in the transition zone with fixed SA interval during right ventricular overdrive pacing determines accessory pathway location in orthodromic reentrant tachycardia

Background: Ventricular overdrive pacing (VOP) produces reset during the transition zone (TZ) of QRS fusion in orthodromic reentrant tachycardia (ORT) and after the TZ in atrioventricular nodal reentrant tachycardia (AVNRT), and this represents a simple diagnostic maneuver to differentiate the 2 tachycardia mechanisms. Objective: The purpose of this study was to determine whether the number of beats with reset in the TZ predicts accessory pathway (AP) location in ORT. Methods: We retrospectively reviewed 57 patients with ORT (21 left-sided AP, 20 septal AP, and 16 right-sided AP) and 20 patients with AVNRT (19 typical AVNRT and 1 atypical AVNRT) who underwent VOP from the right ventricular apex. We analyzed the number of beats with reset during or after the TZ, demonstrated by fixed ventricular stimulus-atrial (SA) interval during VOP. Results: The overall mean tachycardia cycle length [CL] minus VOP CL was 22.6 ± 7.5 ms with no statistical difference between the groups (P = 0.480). The mean number of beats in the TZ with fixed SA interval was 2.5 ± 1.4 for the whole ORT group, 1.1 ± 0.4 for left-sided AP (range 1–2), 2.8 ± 0.9 for septal AP (range 1–5), and 4.0 ± 0.9 for right-sided AP (range 3–6) (P < 0.001). Using a cutoff >2 beats distinguished right- vs. left-sided AP in all cases.

Determining the Site of Accessory Pathways in Orthodromic Reciprocating Tachycardia by Using the Response to Right Ventricular Pacing

Postpacing interval (PPI) after right ventricular (RV) pacing entrainment minus tachycardia cycle length (TCL) with a correction for atrioventricular (AV) node delay (corrected PPI-TCL) was useful to differentiate atrioventricular node reentrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT). However, the value of corrected PPI-TCL in determining the site of the accessory pathway (AP) in ORT has not been investigated. The purpose of this study was to assess whether the corrected PPI-TCL is useful in differentiating ORT using a left-sided AP from a right-sided AP. We studied 52 patients with ORT using a left-sided AP and 13 patients with a right-sided AP. The PPI was measured upon cessation of the RV pacing at a cycle length 10-40 ms shorter than the TCL. The corrected PPI-TCL was calculated from the subtraction of the increment in AV nodal conduction time of the first PPI from the PPI-TCL. The mean corrected PPI-TCL was 83 ± 20 ms in patients with ORT using a left-sided AP and 27 ± 19 ms in patients with a right-sided AP (P ≤ 0.001). All patients with ORT using a left-sided AP except three patients with left septal AP and none of the patients with ORT using a right-sided AP had a corrected PPI-TCL > 55 ms. The corrected PPI-TCL after the RV pacing entrainment is useful to guide differentiating ORT using a left-sided AP from a right-sided AP.

Frequency of fractionated ventricular activation and atrial/ventricular electrogram amplitude ratio at successful ablation target of accessory pathways in patients with Ebstein's anomaly.

Knowledge about local electrogram and atrial/ventricular electrogram amplitude ratio (A/V ratio) at the true atrioventricular ring for successful ablation of accessory pathways (APs) in patients with Ebstein's anomaly is limited. Twenty-two adults with Ebstein's anomaly and APs were managed by 24 sessions of radiofrequency catheter ablation (RFCA). A right atrial/ventricular angiogram with or without 3-dimensional electroanatomic mapping was performed to delineate the true atrioventricular ring and atrialized right ventricle (ARV). Electrograms of successful targets were analyzed. For each right-sided AP target, 2 AP targets matched by location and conduction property from normal hearts were selected as controls, and their A/V ratios were compared. In 32 right-sided APs of all 22 patients, local ventricular activation at successful site presented as normal electrogram in 14, fractionated ventricular electrogram (FVE) in 16, and double ventricular potentials in 2. The bipolar voltage of ARV was markedly lower than in normal hearts. The A/V ratio at the successful target was significantly higher in APs with FVE than in control (1.64 ± 1.34 vs. 0.47 ± 0.19, P < 0.01), and was similar in APs with normal ventricular electrogram and in the control (0.38 ± 0.15 vs. 0.46 ± 0.15, P = 0.1726). The A/V ratio at the successful target with double ventricular potentials (after surgical correction) was 0.30 ± 0.20. All APs were successfully ablated without complications. In patients with Ebstein's anomaly, FVE was found in 50% of the successful targets of APs. High A/V ratio at successful sites with FVE and normal A/V ratio at targets with normal ventricular electrogram can facilitate target recognition and ablation.

Radiofrequency ablation of right-sided accessory pathways in children: how have 3 D systems and cool-tip catheters changed success and recurrence rates?

Radiofrequency ablation of right-sided accessory pathways in children: how have 3 D systems and cool-tip catheters changed success and recurrence rates?

Clinical characteristics of ventricular preexcitation dilated cardiomyopathy induced by accessory pathway

Objective To discuss the characteristics, diagnosis, mechanism and the prognosis of dilated cardiomyopathy(DCM) induced by accessory pathway(AP). Methods The clinical, electrophysiological and echocardiographic characteristics in four cases, who were diagnosed as AP-induced DCM in the Department of Pediatric Cardiology of Beijing Anzhen Hospital, Capital Medical University from Mar.2011 to Aug.2012, were analyzed before and after ablation. Results The electrocardiograms of the 4 patients all indicated type B ventricular preexcitation.The locations of the APs were the right-sided anteroseptum and the free wall.Dyschronous contractions between posterior wall of left ventricle and interventricular septum were demonstrated by M-Mode echo.The basal segments of the interventricular septum turned thin and moved similar to an aneurysm, with typical bulging during end-systole, which was observed in all cases by two-dimension echo.Dyschronous left ventricular contraction was shown by speckle tracing technique.All patients received successful radio frequency current ablations.Their physical activities and growth improved greatly in the 4 cases.The echocardiographic data demonstrated that their left ventricular contraction recovered to synchrony shortly after the ablation, left ventricular ejection fraction recovered to normal and left ventricular end diastolic diameter decreased to almost normal gradually during the follow-up. Conclusions Overt right-sided APs localized in anteroseptum or free wall may have adverse effects on ventricular wall motion and left ventricular function.They can even result in DCM.Dyssynchronous ventricular contraction induced by right-sided overt accessory pathway may be the vital mechanism.AP-induced DCM is an indication for ablation with good prognosis. Key words: Ventricular preexcitation; Speckle tracing; Dilated cardiomyopathy; Dyssynchrony

Adverse effects of type B ventricular pre-excitation on ventricular wall motion and left ventricular function: clinical analysis of 9 cases

To analyze the adverse effects of type B ventricular pre-excitation on ventricular wall motion and left ventricular function and its clinical characteristic. The clinical, electrophysiological and echocardiographic characteristics of the 9 cases with type B ventricular pre-excitation before and after ablation seen between March 2011 and March 2013 were analyzed. The patients aged from 3 to 16 years. Five of them were female. Dyschronous left ventricular contraction was demonstrated by M-Mode echocardiography in all of the cases. The basal segments of the interventricular septum turned thin and moved in a manner similar to that of an aneurysm, with typical bulging during end-systole, which was observed in six cases. All patients received successful RFCAs. The locations of the accessory pathways (APs) were the right-sided anteroseptum (n = 2) and the free wall (n = 7). Their physical activities and growth improved greatly in the four cases with coexisting dilated cardiomyopathy (DCM). The echocardiographic data demonstrated that their LV contraction recovered to synchrony shortly after the ablation, LVEF recovered to normal and LVED decreased to almost normal gradually during the follow-up. Overt right-sided APs may have adverse effects on ventricular wall motion and left ventricular function. They can even result in DCM. Dyssynchronous ventricular contraction induced by right-sided overt accessory pathway may be the vital mechanism. Such kinds of cases are indication for ablation with good prognosis.