Analyses of the Mode of Termination During Diagnostic Ventricular Pacing to Differentiate the Mechanisms of Supraventricular Tachycardias.

OBJECTIVES: The goal of this study was to determine the diagnostic yield of analyzing the mode of termination during ventricular overdrive pacing (VOP) to differentiate the mechanisms of supraventricular tachycardias (SVTs). BACKGROUND: The majority of the diagnostic criteria for VOP rely on successful entrainment, but termination of SVTs is common during VOP. METHODS: We studied 225 SVTs with a 1:1 atrioventricular relationship, including 34 atrial tachycardias, 67 orthodromic reciprocating tachycardias (ORTs) (including 4 ORTs using accessory pathways [APs] with decremental properties), and 124 atrioventricular nodal re-entrant tachycardias. The total pacing prematurity (TPP) needed to reset or terminate the SVT was calculated by using a simplified method, and the post-pacing interval minus the tachycardia cycle length (PPI - TCL) was predicted from the TPP. RESULTS: VOP terminated 87 SVTs (39%). No atrial tachycardias were terminated by VOP in this study. SVT termination occurred after (n = 71) or before (n = 16) atrial resetting. The predicted PPI - TCL was highly correlated with the measured PPI - TCL (r = 0.96; p < 0.001). The TPP had diagnostic accuracy equivalent to the predicted PPI - TCL. The TPP was measurable irrespective of the termination mode and correctly diagnosed ORTs with decremental APs. All ORTs using septal APs and no atrioventricular nodal re-entrant tachycardias had a TPP <125 ms. Considering other criteria evaluable in terminated SVTs, a combined criteria of a TPP <125 ms and atrial capture/termination within the fusion period were specific for ORTs using free-wall APs, except for left anterolateral/lateral sites. CONCLUSIONS: The termination analyses were useful for differential diagnoses of SVTs terminated during VOP.

Internal Cardioverter Defibrillator Indications and Therapies after Atrial Baffle Procedure for d-Transposition of the Great Arteries: A Multicenter Analysis.

BACKGROUND: Sudden cardiac death (SCD) is the most important cause of late mortality after atrial baffle procedure for d-transposition of the great arteries (d-TGA). Experience with internal cardioverter defibrillator (ICD) therapy in this population is limited. We conducted a multicenter cohort study to determine the current state of ICD therapy in individuals after atrial baffle procedure. METHODS: Demographic and clinical data as well as data on device implantation, programming, ICD discharges, and complications after atrial baffle procedure for d-TGA from four German centers were analyzed retrospectively. RESULTS: ICD implantation was undertaken in 33 subjects. ICD implantation was undertaken as primary prevention in 29 (88%) and secondary prevention in four (12%) individuals. There were 21 (64%) subjects with atrial reentrant tachycardia (IART). During a median follow-up of 4.8 years, seven appropriate ICD therapies were delivered in three (10%) individuals with primary prevention indication. No appropriate shocks were documented in subjects with secondary prevention indication. A total of 12 inappropriate ICD discharges occurred in eight (24%) individuals due to IART (n = 6) or lead failure (n = 2). ICD-related complications were noted in seven individuals (21%): lead dislodgement/failure in five (15%) and ICD infection in two subjects (6%). CONCLUSIONS: The majority of individuals received an ICD for primary prevention of SCD, thus representing a liberal attitude of physicians for ICD implantation. During a median follow-up of 4.8 years, the rate of appropriate ICD therapies was low and clearly exceeded by inappropriate ICD discharges. Lead failure and IART were present in >20% of the individuals and were frequent reasons for inappropriate ICD discharges. Facing these results, rigorous treatment of IART and careful ICD programming seems mandatory.

Atrioventricular 1:1 tachycardia effectively terminated by antitachycardia pacing : What is your diagnosis?

This case describes a tachycardia with a 1:1 atrioventricular relationship that was effectively terminated with antitachycardia pacing by the implantable cardioverter defibrillator. The differential diagnosis and clues that allow the reader to establish the correct diagnosis are discussed. The case also serves to analyse technical features of Boston Scientific dual-chamber defibrillators.

Systolic pulmonary and hepatic vein flow reversal due to pacemaker-induced retrograde ventriculoatrial conduction.

Systolic pulmonary and hepatic vein flow reversals can typically be seen with severe atrioventricular (AV) valve regurgitation and during atrial fibrillation (AF). We report the case of a 67-year-old woman who presented with recent-onset exertional dyspnea. Her pacemaker was near end-of-life and reverted to a VVI mode from the preset DDDR mode. Electrocardiography demonstrated retrograde 1:1 ventriculoatrial (VA) conduction and spectral Doppler analysis revealed prominent systolic pulmonary and hepatic vein flow reversals. Symptoms, electrocardiogram (ECG) findings, and the spectral Doppler abnormalities resolved completely following a generator replacement and resumption of DDDR pacing.

Multiple syncope mechanisms coexisting in a Brugada syndrome patient requiring a single therapeutic approach.

We report the case of a Brugada syndrome patient with a history of syncopal and presyncopal episodes and evidence of sinus node and atrioventricular (AV) conduction abnormalities. The patient developed sinus bradycardia, sinoatrial conduction abnormalities, prolonged HV interval, early appearance of AV block, AV nodal reentrant tachycardia and polymorphic ventricular tachycardia in the electrophysiological study. He was treated with a dual-chamber pacemaker defibrillator. At the 9-year follow-up, the patient remained asymptomatic with several episodes of 1:1 AV-relationship tachycardia, interrupted with antitachycardia pacing, while the predominant pacing states of the device were AP-VS and AS-VP for most of the time.

Cardioversion of intraatrial reentrant tachycardia using rate response.

Intraatrial reentrant tachycardia (IART) is the most common long-term, surgical arrhythmia sequela in patients with complex congenital heart disease. The management of IART is challenging. Medications, catheter ablation therapy, and pacemaker therapy have all been utilized as treatment options. Slower tachycardia cycle lengths and 1:1 atrioventricular conduction provide even more challenges with regard to detection and antitachycardia pacing. We describe the use of the rate response feature as a means of patient-initiated cardioversion.

[Intraoperative interruption of an accessory pathway: is it always a long-term cure for arrhythmia?]. / Intraoperative Unterbrechung einer akzessorischen Leitungsbahn: Immer eine langfristige Heilung?

We report the case of a male patient who had undergone successful cardiac surgery about 20 years previously for a posteroseptal accessory pathway that caused almost incessant orthodromic AV reentrant tachycardia, but presented again recently with new onset cardiac arrhythmia. 3D mapping demonstrated scar-related reentrant tachycardia in the right atrium with a critical isthmus between the atriotomy scar and terminal crest, which could be successfully treated using irrigated-tip high-frequency catheter ablation.

Discordant electrical and mechanical atrial delays affect intracavitary electrogram-based cardiac resynchronization therapy optimization.

AIMS: It has been shown that atrioventricular (AV) delay optimization improves cardiac resynchronization therapy (CRT) response. Recently, an automatic algorithm (QuickOpt™, St Jude Medical), able to quickly identify the individual optimal AV interval, has been developed. The algorithm suggests an AV delay based on atrial intracavitary electrogram (IEGM) duration. We hypothesized that the difference between electrical and mechanical atrial delays could affect the effectiveness of QuickOpt method. The aim of this study was to test this hypothesis in 23 CRT patients who were recipients of St. Jude Medical devices. METHODS AND RESULTS: Using echocardiography, aortic flow velocity time integral (VTI) was evaluated at baseline, at QuickOpt suggested AV delay and after reducing it by 25 and 50%. Mechanical inter-atrial delay (MIAD) derived from echo/Doppler and electrical inter-atrial delay (EIAD) derived from IEGM were also analysed. Optimal AV delay was identified by the maximal VTI. In 11 patients (Group 1) the maximal VTI was achieved at the AV delay suggested by the algorithm, in 6 patients (Group 2) after a 25% reduction, and in 6 patients (Group 3) after a 50% reduction. While EIAD was similar among the three groups, MIAD was significantly different (P< 0.001). MIAD was longer than EIAD in Group 1 (P= 0.028) and shorter than EIAD in Groups 2 (P= 0.028) and 3. (P< 0.001). Mechanical inter-atrial delay was the only independent predictor of the AV interval associated with the best VTI (R(2) = 0.77; P< 0.001). CONCLUSION: Our results show that MIAD plays the main role in determining the optimal AV delay, thus caution should be taken when optimizing AV by IEGM-based methods.

Electrophysiological predictors of propafenone efficacy in prevention of atrioventricular nodal re-entrant and atrioventricular re-entrant tachycardia.

AIM: To assess the efficacy of propafenone in prevention of atrioventricular nodal reentrant tachycardia (AVNRT) and orthodromic atrioventricular tachycardia (AVRT) based on the clinical results of arrhythmia recurrence and find the electrophysiological predictor of propafenone effectiveness. METHODS: This retrospective study included 44 participants in a 12-month period, who were divided in two groups: group A - in which propafenone caused complete ventriculo-atrial block and group B - in which propafenone did not cause complete ventriculo-atrial block. RESULTS: Group A had significantly lower incidence of tachycardia than group B (95% vs 70.8%, P=0.038), and complete ventriculo-atrial block predicted the efficacy of propafenone oral therapy in the prevention of tachycardia (sensitivity 87.5%, specificity 52.8%, positive predictive value 95%, negative predictive value 29.2%). Patients with AVNRT in group B who did not experience the recurrences of tachycardia had significantly shorter echo zone before intravenous administration of propafenone than the patients who experienced episodes of sustained tachycardia (median 40 ms [range 15-60 ms] vs 79 ms [range 50-180 ms], P=0.008). CONCLUSION: In patients with non-inducible tachycardia, complete ventriculo-atrial block can be used as an electrophysiological predictor of the efficacy of propafenone oral therapy in the prevention of tachycardia. In patients with non-inducible AVNRT, but without complete ventriculo-atrial block, propafenone was more effective in patients with shorter echo zone of tachycardia.

Characteristics of bundle branch reentrant ventricular tachycardia with a right bundle branch block configuration: feasibility of atrial pacing.

AIMS: We assessed the inducibility of bundle branch reentrant ventricular tachycardia (BBR-VT) with a right bundle branch block (RBBB) configuration in patients with BBR-VT. METHODS AND RESULTS: Eight consecutive patients (5 men, 45+/-18 years old) with inducible BBR-VT were included. We evaluated the clinical and electrophysiological characteristics in these patients to explore the inducible factors of BBR-VT with an RBBB configuration. Six of eight patients had inducible BBR-VT with an RBBB configuration, including four patients with a clinical VT with the same QRS morphology. All patients exhibited an LBBB or RBBB type intraventricular conduction disturbance during sinus rhythm. The mean HV interval at baseline was 79+/-18 ms. The reproducibility of the BBR-VT with an RBBB pattern was achieved by incremental atrial pacing during an isoproterenol infusion in 4/6 patients (67%) and by programmed ventricular stimulation in the other two. After a right bundle ablation, the BBR-VT was no longer inducible in any of the cases. CONCLUSION: Our results indicate that it is not rare to induce BBR-VT with an RBBB configuration. For the induction of an RBBB type BBR-VT, incremental atrial pacing may play a significant role in addition to ventricular pacing.

[Pacemaker ECG quiz: AV sequential pacing--what is happening?]. / Schrittmacher-EKG-Quiz 19: AV-sequenzielle Stimulation--was passiert hier?

The present case of a 55-year-old patient with heart failure displays a complex pacemaker ECG.

Incessant interfascicular reentrant ventricular tachycardia as a result of catheter ablation of the right bundle branch: case report and review of the literature.

A 72-year-old woman developed incessant interfascicular (IF) ventricular tachycardia immediately after successful right bundle branch (RBB) catheter ablation for the treatment of sustained bundle branch reentrant tachycardia. Catheter ablation of the left bundle branch and the left anterior fascicle was successful in eliminating the tachycardia (in 2 different sessions). This report discusses the direct link between the creation of an RBB block and the development of IF tachycardia, in our case, and in prior cases of IF reentry reported in the literature.

Echo determinants of dyssynchrony (atrioventricular and inter- and intraventricular) and predictors of response to cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) has revolutionized not only the treatment of chronic heart failure but also how we assess left ventricular (LV) dysfunction on echo. Increasingly, it has become clear that identifying and quantifying delays in events during the cardiac cycle is an important assessment in LV dysfunction as it has prognostic implications for patients undergoing CRT. The delays in atrioventricular, right-to-left ventricular, and LV segmental contraction have been shown to be important components in cardiac performance, and this review provides an overview of the commonest methods used for these assessments and their implications for selecting patients for biventricular pacing.

Mapping of intraatrial reentrant tachycardias by remote magnetic navigation in patients with d-transposition of the great arteries after mustard or senning procedure.

UNLABELLED: Remote Magnetic Mapping After Mustard/Senning Procedure. INTRODUCTION: Mapping of intraatrial reentrant tachycardia (IART) still presents a challenge in complex congenital heart disease. The goal of this work was to present our initial experience with remote magnetic navigation (RMN) for mapping of IART in four patients after the atrial switch procedure (Mustard n = 1, Senning n = 3) for d-transposition of the great arteries. METHODS: Three-dimensional (3D) mapping of the systemic venous atrium and the pulmonary venous atrium (PVA) was performed using RMN (Niobe) in conjunction with 3D mapping (CartoRMT). The maps were fused with a CT-based 3D anatomy. RESULTS: All patients had cavotricuspid isthmus-dependent IART with a mean atrial cycle length of 305 ms. Mapping of both atria (PVA retrogradely by passing the aortic and tricuspid valve) was feasible and safe. The procedure time for IART mapping ranged from 210 to 320 minutes with a mean of 251 minutes. The fluoroscopy time for IART mapping ranged from 15.8 to 45.0 minutes (mean 31.6 minutes) for patients, and ranged from 12.3 to 24.3 minutes with a mean of 19.5 minutes for physicians. No procedural complications occurred. CONCLUSION: Precise mapping of IART in the complex anatomical structures after an atrial switch procedure was feasible and safe using RMN. The maneuverability of the catheter was possible even with a retrograde access crossing two valves. Further reduction of procedural and fluoroscopy times for both patients and physicians seems possible.

Impact of cryoablation catheter size on success rates in the treatment of atrioventricular nodal re-entry tachycardia in 160 patients with long-term follow-up.

AIMS: To determine the efficacy and safety of cryoablation for the treatment of atrioventricular nodal re-entry tachycardia (AVNRT). METHODS AND RESULTS: We analysed the procedural characteristics, acute success, and recurrence rates of 160 consecutive patients treated with cryoablation for the AVNRT and followed up for 18 months. Mean procedural time was 119.1 +/- 3.7 min, with an average of 4.6 +/- 0.2 Cryo lesions and an acute procedural success rate of 93%. Recurrence rates were 19 (11.9%) cases and were significantly higher in the 4 mm cryocatheter-treated group (12/59, 16.9%), compared with the 6 mm cryocatheter-treated group (9/101, 6.9%, P = 0.01). Recurrence rates were greater where slow pathway block was not achieved 8/12 (66.7%), compared with complete slow pathway block 11/129 (8.5%, P < 0.0001). Recurrence was significantly more likely if atrial echo beats were still present after cryoablation, 12/130 (9.2%) patients with no recurrence vs. 7/19 (36.8%) patients with recurrence (P < 0.0001). CONCLUSION: Cryoablation is a safe and efficacious treatment for AVNRT. Complete slow pathway block is associated with long-term success, together with the use of the larger 6 mm cryocatheter. There is always a risk of heart block with radiofrequency ablation, although this experience confirms previous findings that the risk with Cryo is zero.

Importance of electrocardiography in the assessment and management of heart failure: a case report.

Restoring and maintaining optimal electrical activation of the cardiac chambers as well as atrioventricular synchrony are important aspects of heart failure management. The 12-lead electrocardiogram remains a simple and cost-effective diagnostic tool that can provide important clues in achieving this goal. We report a case where careful interpretation of the 12-lead electrocardiogram led to the diagnosis of pacemaker syndrome. This recognition led to a therapeutic intervention that resulted in the resolution of the patient's heart failure symptoms. The importance of electrocardiography and atrioventricular synchrony in the management of heart failure will also be discussed.