Three-dimensional mapping in the electrophysiological laboratory.

Investigation and catheter ablation of cardiac arrhythmias are currently still based on optimal knowledge of arrhythmia mechanisms in relation to the cardiac anatomy involved, in order to target their crucial components. Currently, most complex arrhythmias are investigated using three-dimensional electroanatomical navigation systems, because these are felt to optimally integrate both the anatomical and electrophysiological features of a given arrhythmia in a given patient. In this article, we review the technical background of available three-dimensional electroanatomical navigation systems, and their potential use in complex ablations.

Comprehensive Multicenter Study of the Common Isthmus in Post-Atrial Fibrillation Ablation Multiple-Loop Atrial Tachycardia.

BACKGROUND: Characteristics of multiple-loop atrial tachycardia (AT) circuits have never precisely examined. METHODS: In 193 consecutive post-atrial fibrillation ablation patients with AT, 44 multiple-loop ATs including 42 dual-loop AT and 2 triple-loop AT in 41 (21.2%) were diagnosed with the high-resolution mapping system and analyzed off-line. RESULTS: In dual-loop ATs, 3 types were identified: type M, a combination of 2 anatomic macroreentrant ATs (AMATs) in 19 (43.2%); type MN, with 1 AMAT and 1 non-AMAT in 12 (27.3%); and type N with 2 non-AMATs in 11 (25.0%). The remaining 2 triple-loop ATs (4.5%) were a combination of perimitral-, roof-dependent-, and non-AMAT. At least 1 AMAT was included in 33 (75.0%), and 1 non-AMAT in 25 (56.8%). Of the ATs with at least 1 non-AMAT circuit, a pulmonary vein formed part of the circuit in 16/25 (64.0%). The length of the common isthmus was 3.6±1.4 cm in type M, 1.6±0.7 cm in type MN, and 1.1±0.7 cm in type N (P<0.0001). The area of the common isthmus was 12.92±7.68, 2.46±1.53, and 0.90±0.81 cm2, in Type M, MN, and N (P<0.0001). The narrowest width of the common isthmus was 1.8±0.7 cm, 1.1±0.3 cm, and 0.7±0.3 cm in type M, MN, and N (P<0.0001), respectively. The electrograms in the common isthmus showed longer duration and lower voltage in type N, type MN, and type M (duration: 106±25 ms, 87±27 ms, and 69±27 ms; P=0.006; and voltage: 0.06±0.02 mV, 0.22±0.21 mV, and 0.57±0.50 mV; P<0.0001), respectively. CONCLUSIONS: Multiple-loop ATs are complex, frequently including anatomic circuits. They have specific characteristics determined by the combination of AMAT and non-AMAT.

Premature ventricular contraction-induced cardiomyopathy: Related clinical and electrophysiologic parameters.

BACKGROUND: Factors associated with premature ventricular contraction-induced cardiomyopathy (PVCi-CMP) remain debated. OBJECTIVE: The purpose of this study was to test the correlation of various factors to the presence PVCi-CMP in a large multicenter population. METHODS: One hundred sixty-eight consecutive patients referred for ablation of frequent premature ventricular contractions (PVCs) were included. Patients were divided into 2 groups: group 1 with suspected PVCi-CMP (96 patients, ejection fraction 38% ± 10%, left ventricular end-diastolic diameter 62 ± 8 mm, with or without additional structural heart disease); and group 2 (control group, 72 patients with normal ejection fraction and left ventricular dimensions). Various clinical and electrophysiologic parameters were compared between groups. RESULTS: In univariate analysis, left ventricular origin of PVC, lack of palpitations, long PVC coupling interval, epicardial origin of the focus, long sinus beat QRS duration, male gender, high PVC burden, presence of polymorphic PVCs, high PVC QRS duration, and older age were significantly related to the presence of PVCi-CMP. In multivariate analysis, only lack of palpitations, PVC burden, and epicardial origin remained significantly and independently correlated with the presence of cardiomyopathy. Even if sinus QRS duration or PVC left ventricular origin were also found independently linked to PVCi-CMP in the whole population, they were no longer correlated when patients with additional heart disease were excluded. CONCLUSION: Lack of palpitations, PVC burden, and epicardial origin are independent factors that identify patients prone to developing PVCi-CMP.

[Factors Associated with Direct Oral Anticoagulants versus Vitamin K Antagonists in Patients with Non-valvular Atrial Fibrillation]. / Facteurs associés à la prescription d'anticoagulants oraux directs versus anti-vitamines K dans la fibrillation atriale non valvulaire.

OBJECTIVE: Describing the factors associated with direct oral anticoagulants (DOA) prescription in patients with atrial fibrillation (AF). METHOD: This study was performed in Toulouse on a cohort of patients received in rhythmology consultation, treated with vitamin K antagonists (VKA) or DOA for AF. A multivariate model was performed using logistic regression to describe the factors associated with DOA prescription and secondly, those associated with discontinuation of the anticoagulant. RESULTS: Among the 140 patients included, 96 (66%) were treated with VKA and 48 (34%) with DOA. Recent AF diagnosis (OR 7.52, 95% CI [2.41;23.29], p = 0.001), previous exposure to VKA (OR 17.11, 95% CI [4.48;60.91], p<0.001), and no current exposure to anti-platelet agents (APA) (OR 7.69, 95% CI [1.22; 50.00], p = 0.030) were associated to DOA prescription. Discontinuation of the anticoagulant (n=24) was associated to DOA intake (OR 2.71, 95% CI [1.21; 6.08], p = 0.016). DISCUSSION: DOA are less prescribed than VKA in patients treated with APA. DOA switch to VKA was not systematic in patients diagnosed for a long time. However, international normalized ratio (INR) values were stable in most of patients treated with VKA at the switching to DOA. A more powerful study would confirm the factors associated with DOA prescription.

Detection of T-wave beat-by-beat variations prior to ventricular arrhythmias onset in ICD-stored intracardiac electrograms: the Endocardial T-Wave Alternans Study (ETWAS).

BACKGROUND: The aim of the Endocardial T-Wave Alternans Study was to prospectively assess the presence of T-wave alternans (TWA) or beat-to-beat repolarization changes on implantable cardioverter-defibrillator (ICD)-stored electrograms (EGMs) immediately preceding the onset of spontaneous ventricular tachycardia (VT) or fibrillation (VF). METHODS: Thirty-seven VT/VF episodes were compared to 116 baseline reference EGMs from the same 57 patients. A Bayesian model was used to estimate the T-wave waveform in each cardiac beat and a set of 10 parameters was selected to segment each detected T wave. Beat-by-beat differences in each T-wave parameter were computed using the absolute value of the difference between each beat and the following one. Fisher criterion was used for determining the most discriminant T-wave parameters, then top-M ranked parameters yielding a normalized cumulative Fisher score > 95% were selected, and analysis was applied on these selected parameters. Simulated TWA EGMs were used to validate the algorithm. RESULTS: In the simulation study, TWA was detectable even in the case of the smallest simulated alternans of 25 µV. In 13 of the 37 episodes (35%) occurring in nine of 16 patients, significant larger beat-to-beat variations before arrhythmia onset were detected compared to their respective references (median one positive episode per patient). Parameters including the T-wave apex amplitude seem the more discriminant parameters. CONCLUSIONS: Detection of beat-by-beat repolarization variations in ICD-stored EGMs is feasible in a significant subset of cases and may be used for predicting the onset of ventricular arrhythmias.

Incessant atrio-ventricular node reentrant tachycardia induced by unapparent dual atrio-ventricular node conduction.

We present the case of a patient with incessant slow-fast atrio-ventricular (AV) node reentrant tachycardia induced by dual AV node conduction with aborted conduction to the ventricles. The unapparent conduction over the slow pathway was suspected here because of spontaneous nodal echoes without QRS complexes occurring during sinus rhythm, manifested as isolated premature atrial beats and which repetitively induced the tachycardia.

Temporal and spectral analysis of ventricular fibrillation in humans.

PURPOSES: Analysing ventricular fibrillation (VF) rate and regularity at different sites and at different times may help understanding some of the mechanisms underlying VF in humans. METHODS: Twelve episodes of VF (19.4 ± 5.6 s) were induced during electrophysiological study in eight men (63 ± 14 years old). Calculation of dominant frequency (DF) by fast Fourier transform, short-time Fourier transform, and analysis of the pitch frequency [VF cycle length duration (CL)] were performed. For each episode, we analysed the 12 lead-surface ECG, three unipolar, 10 near-field, and three far-field bipolar recordings by means of three quadripolar catheters positioned at the right ventricular apex (RV apex), right ventricular outflow tract, and at the coronary sinus (exploring the lateral left ventricular epicardium) (LV). RESULTS: Fast and regular discrete activation covered the whole duration of every intracardiac recording, whereas surface ECG consistently displayed chaotic and fibrillatory pattern. DF (5.25 ± 0.64 Hz) was very similar on surface ECG recordings and in various intracardiac recordings. Intracardiac activation was rather regular during VF despite the fibrillatory process with very low SD of the CL. There were some significant inverse correlations between VF rate and VF regularity. Intracardiac sites displaying the fastest and most regular activations were those including the RV apex. VF rate and stability slightly increased over time. Finally, the parameters exploring the VF rate were found to be well correlated together, as well as parameters of VF regularity CONCLUSIONS: Human VF induced during electrophysiological study has a clear DF of activation and appears quite regular in intracardiac recordings. There is some spatial heterogeneity, which needs to be more detailed in order to localize possible driving sources. Fastest VF are the most regular. Rate and stability tend to increase during the initial phases of VF.

Variations in duration and composition of the excitable gap around the tricuspid annulus during typical atrial flutter.

BACKGROUND: Differences in the duration of the excitable gap along the reentry circuit during typical atrial flutter are poorly known. AIM: To prospectively evaluate and compare the duration and composition of the excitable gap during typical counterclockwise atrial flutter in different parts of the circuit all around the tricuspid annulus. METHODS: The excitable gap was determined by introducing a premature stimulus at various sites around the tricuspid annulus during typical counterclockwise atrial flutter in 34 patients. Excitable gap was calculated as the difference between the longest resetting coupling interval and the effective atrial refractory period. RESULTS: The duration of the excitable gap, the effective atrial refractory period and the resetting coupling interval differed significantly along the tricuspid annulus. Duration of excitable gap was significantly longer at the low lateral right atrium (79±22 ms) than at the cavotricuspid isthmus (66±23 ms; P=0.002). The effective atrial refractory period was significantly longer at the cavotricuspid isthmus (160±26 ms) than at the high lateral right atrium (149±29 ms; P=0.004). Other locations, such as coronary sinus ostium, right atrial septum and atrial roof displayed intermediate values. CONCLUSION: The duration of the excitable gap differed significantly along the tricuspid annulus, with a larger excitable gap at the lateral right atrium and a shorter excitable gap at the cavotricuspid isthmus, because of longer refractory periods at the isthmus.