The great deceiver: a case series of 'double fire' atrioventricular nodal response.

BACKGROUND: The 'double fire' (DF) atrioventricular (AV) nodal response is a rare mechanism of two ventricular electrical activations following a single atrial beat due to dual AV node physiology. DF AV nodal response is often misdiagnosed and may lead to unnecessary invasive procedures. CASE SUMMARY: We describe a series of three cases with distinct clinical manifestations of DF AV nodal response: Patient 1 remained symptomatic after slow pathway modification for common AV nodal re-entry tachycardia. Patient 2 was misdiagnosed as having junctional bigeminy and developed heart failure with reduced left ventricle ejection fraction. Patient 3 was misdiagnosed as having atrial fibrillation (AF) and underwent two pulmonary vein isolation (PVI) procedures, without clinical improvement. All patients underwent an electrophysiological study (EPS) during which DF AV nodal response was confirmed and treated with radiofrequency ablation of the slow pathway. All patients were afterwards relieved from their symptoms. DISCUSSION AND CONCLUSION: DF AV nodal response is a rare electrophysiological phenomenon which can be clinically misinterpreted as other common arrhythmias, such as premature junctional bigeminy or AF and can contribute to tachycardia induced cardiomyopathy. Typical electrocardiogram- and EPS-derived findings can be indicative for DF AV nodal response. DF AV nodal response can be easily and effectively treated by slow pathway ablation

High-resolution structural-functional substrate-trigger characterization: Future roadmap for catheter ablation of ventricular tachycardia

Introduction Patients with ventricular tachyarrhythmias (VT) are at high risk of sudden cardiac death. When appropriate, catheter ablation is modestly effective, with relatively high VT recurrence and complication rates. Personalized models that incorporate imaging and computational approaches have advanced VT management. However, 3D patient-specific functional electrical information is typically not considered. We hypothesize that incorporating non-invasive 3D electrical and structural characterization in a patient-specific model improves VT-substrate recognition and ablation targeting.Materials and methods In a 53-year-old male with ischemic cardiomyopathy and recurrent monomorphic VT, we built a structural-functional model based on high-resolution 3D late-gadolinium enhancement (LGE) cardiac magnetic resonance imaging (3D-LGE CMR), multi-detector computed tomography (CT), and electrocardiographic imaging (ECGI). Invasive data from high-density contact and pace mapping obtained during endocardial VT-substrate modification were also incorporated. The integrated 3D electro-anatomic model was analyzed off-line.Results Merging the invasive voltage maps and 3D-LGE CMR endocardial geometry led to a mean Euclidean node-to-node distance of 5 & PLUSMN; 2 mm. Inferolateral and apical areas of low bipolar voltage ( 0.4) and with higher transmurality of fibrosis. Areas of functional conduction delay or block (evoked delayed potentials, EDPs) were in close proximity to 3D-LGE CMR-derived heterogeneous tissue corridors. ECGI pinpointed the epicardial VT exit at & SIM;10 mm from the endocardial site of origin, both juxtaposed to the distal ends of two heterogeneous tissue corridors in the inferobasal left ventricle. Radiofrequency ablation at the entrances of these corridors, eliminating all EDPs, and at the VT site of origin rendered the patient non-inducible and arrhythmia-free until the present day (20 months follow-up). Off-line analysis in our model uncovered dynamic electrical instability of the LV inferolateral heterogeneous scar region which set the stage for an evolving VT circuit.Discussion and conclusion We developed a personalized 3D model that integrates high-resolution structural and electrical information and allows the investigation of their dynamic interaction during arrhythmia formation. This model enhances our mechanistic understanding of scar-related VT and provides an advanced, non-invasive roadmap for catheter ablation

Prognostic Value of Left Ventricular Deformation Parameters in Patients with Severe Aortic Stenosis: A Pilot Study of the Usefulness of Strain Echocardiography

Background: In patients with aortic stenosis, subtle alterations in myocardial mechanics can be detected by speckle-tracking echocardiography before reduction of left ventricular ejection fraction (LVEF). Methods: In this prospective study, 162 patients with aortic stenosis with an average aortic valve area of 0.7 ± 0.2 cm2 and a mean LVEF of 60 ± 11% were included. Global longitudinal strain (GLS) and mechanical dispersion (SD of time from Q/R on the electrocardiogram to peak strain in 16 left ventricular segments) were assessed using echocardiography, and all-cause mortality (n = 37) was recorded during 37 ± 13 months of follow-up. Results: Overall, nonsurvivors had more pronounced mechanical dispersion and worse GLS compared with survivors (74 ± 24 vs 61 ± 18 msec [P < .01] and −14.5 ± 4.4% vs −16.7 ± 3.6% [P < .01], respectively). In the 42 conservatively treated patients without surgical aortic valve replacement, a similar pattern was observed in nonsurvivors versus survivors (mechanical dispersion, 80 ± 24 vs 57 ± 14 msec [P < .01]; GLS, −14.0 ± 4.9% vs −17.1 ± 3.8% [P = .04], respectively). Mechanical dispersion was significantly associated with mortality (hazard ratio per 10-msec increase, 1.23; 95% CI, 1.07–1.42; P < .01) in a Cox model adjusted for LVEF and with aortic valve replacement treatment as a time-dependent covariate. Continuous net reclassification improvement showed that mechanical dispersion was incremental to LVEF, GLS, and valvulo-arterial impedance when adjusting for aortic valve replacement treatment in the total population. Conclusion: Increased mechanical dispersion may be a risk marker providing novel prognostic information in patients with aortic stenosis

High-resolution structural-functional substrate-trigger characterization: Future roadmap for catheter ablation of ventricular tachycardia

Introduction: Patients with ventricular tachyarrhythmias (VT) are at high risk of sudden cardiac death. When appropriate, catheter ablation is modestly effective, with relatively high VT recurrence and complication rates. Personalized models that incorporate imaging and computational approaches have advanced VT management. However, 3D patient-specific functional electrical information is typically not considered. We hypothesize that incorporating non-invasive 3D electrical and structural characterization in a patient-specific model improves VT-substrate recognition and ablation targeting. Materials and methods: In a 53-year-old male with ischemic cardiomyopathy and recurrent monomorphic VT, we built a structural-functional model based on high-resolution 3D late-gadolinium enhancement (LGE) cardiac magnetic resonance imaging (3D-LGE CMR), multi-detector computed tomography (CT), and electrocardiographic imaging (ECGI). Invasive data from high-density contact and pace mapping obtained during endocardial VT-substrate modification were also incorporated. The integrated 3D electro-anatomic model was analyzed off-line. Results: Merging the invasive voltage maps and 3D-LGE CMR endocardial geometry led to a mean Euclidean node-to-node distance of 5 ± 2 mm. Inferolateral and apical areas of low bipolar voltage (0.4) and with higher transmurality of fibrosis. Areas of functional conduction delay or block (evoked delayed potentials, EDPs) were in close proximity to 3D-LGE CMR-derived heterogeneous tissue corridors. ECGI pinpointed the epicardial VT exit at ∼10 mm from the endocardial site of origin, both juxtaposed to the distal ends of two heterogeneous tissue corridors in the inferobasal left ventricle. Radiofrequency ablation at the entrances of these corridors, eliminating all EDPs, and at the VT site of origin rendered the patient non-inducible and arrhythmia-free until the present day (20 months follow-up). Off-line analysis in our model uncovered dynamic electrical instability of the LV inferolateral heterogeneous scar region which set the stage for an evolving VT circuit. Discussion and conclusion: We developed a personalized 3D model that integrates high-resolution structural and electrical information and allows the investigation of their dynamic interaction during arrhythmia formation. This model enhances our mechanistic understanding of scar-related VT and provides an advanced, non-invasive roadmap for catheter ablation

Heritability in a SCN5A-mutation founder population with increased female susceptibility to non-nocturnal ventricular tachyarrhythmia and sudden cardiac death

BACKGROUND: Heritable cardiac-sodium channel dysfunction is associated with various arrhythmia syndromes, some predisposing to ventricular fibrillation. Phenotypic diversity among carriers of identical-by-descent mutations is often remarkable, suggesting influences of genetic modifiers. OBJECTIVE: The purpose of this study was to identify a unique SCN5A-mutation founder population with mixed clinical phenotypes and sudden cardiac death, and to investigate the heritability of electromechanical traits besides the SCN5A-mutation effect. METHODS: The 16-generation founder population segregating SCN5A c.4850_4852delTCT, p.(Phe1617del), was comprehensively phenotyped. Variance component analysis was used to evaluate the mutation's effects and assess heritability. RESULTS: In 45 p.(Phe1617del) positives, the mutation associated strongly with QTc prolongation (472 ± 60 ms vs 423 ± 35 ms in 26 mutation negatives; P <.001; odds ratio for long-QT syndrome22.4; 95% confidence interval 4.5–224.2; P <.001) and electromechanical window (EMW) negativity (−29 ± 47 ms vs 34 ± 26 ms; P <.001). Overlapping phenotypes including conduction delay and Brugada syndrome were noted in 19. Polymorphic ventricular tachyarrhythmias occurred mostly in the daytime, after arousal-evoked heart-rate acceleration and repolarization prolongation. Cox proportional hazards regression analysis revealed female gender as an independent risk factor for cardiac events (hazard ratio 5.1; 95% confidence interval 1.6–16.3; P = .006). p.(Phe1617del) was an important determinant of QTcbaseline, QTcmax, and EMW, explaining 18%, 28%, and 37%, respectively, of the trait’s variance. Significant heritability was observed for PQ interval (P = .003) after accounting for the p.(Phe1617del) effect. CONCLUSION: This SCN5A-p.(Phe1617del) founder population with phenotypic divergence and overlap reveals long-QT syndrome-related and arousal-evoked ventricular tachyarrhythmias with a female preponderance. Variance component analysis indicates additional genetic variance for PQ interval hidden in the genome, besides a dominant p. .(Phe1617del) effect on QTc and EMW