Neurocardiogenic syncope is a common disorder. It is diagnosed by obtaining a detailed history and performing a head-up tilt test, with or without drug provocation. Several studies have been performed pertaining to its management. However, no treatment, whether pharmacological or non-pharmacological, except for counterpressure maneuvers and daily orthostatic tilt training, has been proven effective. Randomized studies of therapies for neurocardiogenic syncope are needed.

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Patterns of left atrial (far-field signals) or coronary sinus (CS) muscle (near-field) have been defined in CS recordings. The purpose of this study was to define the activation patterns from the coronary sinus in patients with anterior and posterior type of atrioventricular nodal reentrant tachycardia (AVNRT) circuits.
Methods and Results: This retrospective study involved a total of 149 patients with 155 episodes of AVNRT which were divided into 3 patterns. In the anterior pattern (123 tachycardias), the atrial deflection from the His bundle electrogram preceded that from the proximal CS electrogram. In the posterior pattern (23 tachycardias), the proximal CS electrogram (CSp) was recorded earlier than the His bundle atrial electrogram. In the left atrial pattern (9 tachycardias), activation of distal CS sites preceded both proximal CS and atrial activation from the His bundle electrogram. A decapolar catheter with a 5-mm inter-electrode distance was used for CS recording. The CS electrograms were analyzed to determine the total signal duration as well as the duration of the initial component. An initial slow wave was defined as a duration exceeding 10 ms. 1) The duration of the initial component in patients with the anterior pattern was longer than in those with the posterior pattern in CSp (7.3±3.1 ms vs. 4.5±2.0 ms), CS7-8 (7.4±2.9 ms vs. 3.8±1.5 ms), CS5-6 (7.3 ms ± 3.3 ms vs. 4.4 ms ± 2.5 ms) and CS3-4 (6.7 ms ± 2.4 ms vs. 4.5 ms ± 2.0 ms) (p < 0.01). 2) Similarly the total electrogram duration in the CS was longer in patients with an anterior compared to a posterior pattern in CSp (38.3 ms ± 10.1 ms vs. 26.8±6.1 ms), CS7-8 (31.8 ms ± 6.6 ms vs. 27.2 ms ± 6.0 ms), CS5-6 (31.3 ms ± 6.8 ms vs. 26.5 ms ± 4.9 ms), and CS3-4 (30.0 ms ± 6.3 ms vs. 25.0 ms ± 5.1 ms) (p < 0.01). 3) The percentage of tachycardias showing an initial slow wave followed by rapid activation was higher for anterior pattern patients compared with posterior pattern patients in CSp (62% vs. 13%), CS7-8 (79% vs. 4%), CS5-6 (72% vs. 4%), CS3-4 (54% vs. 9%) and distal CS (47% vs. 0%) (p < 0.01).
Conclusions: The pattern of an initial slow wave followed by a rapid wave in the CS was characteristic of an anterior AVNRT circuit and is explained by the initial involvement of far field left atrial components. In contrast, the predominant early rapid waves in the posterior AVNRT circuit are compatible with early CS activation from the right atrium.

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We evaluated efficacy and safety of occlusive radiofrequency catheter ablation (o-RFA) using our thermal balloon catheter (TBC) at superior vena cava (SVC)-right atrial (RA) junction (SVCJ) compared to that of RFA with a standard-tip catheter. Methods: To electrically isolate (SVCI) SVC from RA in 10 pigs (group 1), the initial o-RFA at a balloon surface temperature of 53.9±3.0°C for 3–5 min (13.56 MHz) was achieved at the SVCJ completely obstructed with an inflated balloon. If unsuccessful, subsequent o-RFA was repeated in a ≤5°C increments until reaching either SVCI or sinus arrest. Before and after each o-RFA, stimulation protocol from the RA was performed. Additionally, in 5 different pigs (group 2), RFA at 55°C (≤50 W) for 1 min with a 4 mm-tip catheter was achieved at multiple sites along the SVCJ. Finally, the neighboring tissues of the SVCJ were histologically investigated. Results: In group 1, successful SVCI could be easily accomplished at the final temperature of 57.2±2.4°C; however, in 3 pigs, a new atrial tachycardia was induced after o-RFA at <55°C and in 2 pigs sinus arrest occurred during o-RFA at 60°C. Histologically, transmural and circumferential contraction band necrosis was mainly confirmed around the SVCJ without damage to collateral tissue. In group 2, coagulation necrosis occupied almost all the ablative lesions, leading to severe degeneration of collateral tissue. Conclusion: O-RFA at the SVCJ may be more feasible and safer than RFA.

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Introduction: Some studies have reported that transmural dispersion of repolarization (TDR) is involved in the onset of ventricular arrhythmia. We investigated the effects of nicorandil (NIC) and nifekalant (NIF) injected into the pericardial space, on TDR and T waves in the pig. Methods and Results: We injected NIC 4 or 8 mg and NIF 50 or 100 mg at intervals into the pericardial space for eleven pigs. The effects of these drugs were investigated on the effective refractory period (ERP) between the endocardial and epicardial myocardial cells, as well as on QT time, QT peak-end (QTcpe) as an index of TDR, and T waveforms, respectively. QTcpe increased from 91±21 to 116±19 msec, 2.8 min after injection of NIC (p < 0.01), although corrected QT (QTc) interval did not changed. But 5.5 min after injection, QTc decreased while QTcpe recovered. T wave amplitude significantly increased, and epicardium ERP decreased. When NIF was injected, TDR decreased from 55±10 msec to 44±8 msec (p < 0.01) although QTc did not change. In a later phase, QTc increased (p < 0.01) and QTcpe recovered. T wave amplitude rapidly decreased and became negative. Conclusion: Injected into the pericardial space, NIC and NIF brought about certain changes in ERP, QT and T waveform. Furthermore, NIC increased TDR while NIF decreased TDR.

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A 28-year-old woman who had undergone Fontan surgery for tricuspid atresia at 6 years of age was admitted to Nihon University Hospital due to syncope. Supraventricular tachycardia at 141 beats/min was induced with isoproterenol infusion during a tilt table test. The patient showed atresia of the right atrial orifice of the coronary sinus with persistent drainage into the left superior vena cava. Electrophysiological study was performed. Atrial tachycardia (AT) was induced by rapid atrial pacing. The AT originated in the lower lateral right atrium and electroanatomical mapping showed a focal origin. After successful ablation of the AT, two additional ATs were induced. These ATs were also shown to be of focal origin and were successfully ablated without recurrence during follow-up.

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During cardiac surgery temporary epicardial atrial and ventricular leads are placed in case cardiac pacing is required postoperatively. We present the first reported series of patients with reversal of atrioventricular electrodes in the temporary pacemaker without any consequent deleterious hemodynamic effect. We review the electrocardiographic findings and discuss the findings that lead to the discovery of atrioventricular lead reversal.

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