Spiky Potential Research Articles

Electrophysiological characteristics and catheter ablation of ventricular arrhythmias arising from the superior septal left ventricle

Background and aimsElectrophysiological characteristics and radiofrequency catheter ablation (RFCA) of premature ventricular contractions (PVCs) originating from the superior septal left ventricle (SSLV) have not yet been fully characterized.Methods and resultsThis study included 247 patients who underwent RFCA for PVCs arising from the ventricular outflow tract between February 2020 and August 2022. The successful ablation site was on the SSLV in 37 of the 247 patients. In 12 (32.4%) of those 37 patients, a low amplitude and high frequency spiky potential (SP) was recognized. Five patients showed a narrow QRS duration (86.8 ± 4.6 ms), with a discrete SP observed in PVCs and sinus rhythm, which showed an isoelectric line with the ventricular electrogram at the earliest activation site. Seven patients showed a wide QRS duration (131.6 ± 4.5 ms), with SP observed in PVCs without an isoelectric line with the ventricular electrogram. RFCA was successful at the site of the earliest SP in all 12 patients. The time from SP onset at the successful ablation site to the QRS onset (local activation time) was 30 ± 12 ms, which differed significantly from that for the remaining 25 patients withoutSP(22.1 ± 7.1 ms, P < 0.05).ConclusionsSPs were recorded in 12 (32.4%) of the 37 patients with PVCs originating from the SSLV. The morphology of the PVCs may show a narrow or wide QRS duration and the target site for successful ablation should be identified by the earliest SP.

Relationship between the atrial-activation pattern around the triangle of Koch and successful ablation sites in slow-fast atrioventricular nodal reentrant tachycardia.

The precise details of atrial activation around the triangle of Koch (ToK) remain unknown. We evaluated the relationship between the atrial-activation pattern around the ToK and success sites for slow-pathway (SP) modification ablation in slow-fast atrioventricular reentrant tachycardia (AVNRT). Thirty patients with slow-fast AVNRT who underwent successful ablation were enrolled. Atrial activation around the ToK during sinus rhythm was investigated using ultra-high-density mapping pre-ablation. The relationships among features of atrial-activation pattern and success sites were examined. Of 30 patients (22 cryoablation; 8 radiofrequency ablation), 26 patients had a collision site of two wavefronts of delayed atrial activation within ToK, indicating a success site. The activation-search function of Lumipoint software, which highlights only atrial activation with a spatiotemporal consistency, showed non-highlighted area on the tricuspid-annulus side of ToK. In 23 of the patients, a spiky potential was recorded at that collision site outside the Lumipoint-highlighted area. Fifteen cryoablation patients with a success site coincident with a collision site outside the Lumipoint-highlighted area had significantly more frequent disappearances of SP after initial cryoablation (46.7% vs. 0%, p = .029), fewer cryoablations (3.7 ± 1.8 vs. 5.3 ± 1.3, p = .045), and shorter procedure times (170 ± 57 vs. 228 ± 91 min, p = .082) compared to the seven cryoablation patients without such sites. Four patients had transient AV block by ablation inside the Lumipoint-highlighted area with fractionated signals, but no patient developed permanent AV block or recurrence post-procedure (median follow-up: 375 days). SP modification ablation at the collision site of atrial activation of the tricuspid-annulus side along with a spiky potential could provide a better outcome.

Nodeless wave functions, spiky potentials, and the description of a quantum system in a quantum environment

A quantum system $\mathcal{Q}$ is characterized by a single potential $v$ and its eigenstates. While $v$ is usually postulated for a given physical problem, it represents the interaction with an implicit environment $\mathcal{E}$. We use the exact factorization to show how $v$ emerges if the quantum environment is explicitly taken into account. In general, each eigenstate of the supersystem $\mathcal{S}=\mathcal{Q}\ensuremath{\cup}\mathcal{E}$ corresponds to a different potential ${v}_{j}$ and state ${\ensuremath{\chi}}_{j}$ of $\mathcal{Q}$. Such a state ${\ensuremath{\chi}}_{j}$ typically has no nodes and is the ground state of ${v}_{j}$, even if the corresponding state of the supersystem is an excited state. There are however two exceptions. First, if the energy scale for exciting $\mathcal{Q}$ is much smaller than for exciting $\mathcal{E}$, the potentials ${v}_{j}$ are similar in shape and differ only by sharp spikes. An excitation of $\mathcal{S}$ can then be viewed as an excitation of $\mathcal{Q}$ with its environment being unaffected, and $\mathcal{Q}$ is approximately described by a single spikeless potential $v$ and its eigenstates. Second, ${\ensuremath{\chi}}_{j}$ can sometimes have exact nodes, e.g., due to the symmetry of the problem, and is the excited state of a spikeless potential. We explain and investigate the two cases with model systems to illustrate the intricacies of the separation of a quantum system from its environment. As an application, we use the equivalence of ${\ensuremath{\chi}}_{j}$ being either an excited state of a spikeless potential or the ground state of a spiky potential: For one-dimensional systems, we provide a method to calculate the location of the nodes of an excited state from the calculation of a ground-state wave function. This approach can also be conceptually useful for the computationally hard problem of calculating highly excited states or many-fermion systems.

Electrophysiological characteristics of the earliest activation site in idiopathic right ventricular outflow tract arrhythmias under mini‐electrode mapping

Right ventricular outflow tract ventricular arrhythmias (RVOT VAs) often originate in the voltage-transitional zone. The target electrogram could be compromised by the architecture of the roving catheter. Mini-electrodes could improve the mapping resolution, especially in low-voltage areas. The aim was to assess the electrophysiological characteristics of the earliest activation site (EAS) of RVOT VAs during mapping using mini-electrodes. Twenty-seven patients with RVOT-type VAs were mapped using Orion mini-electrodes and the Rhythmia mapping system. Bipolar and unipolar electrograms were analyzed and compared with conventional ablation catheter recordings. Twenty-five patients (25 of 27) were successfully mapped and ablated at the RVOT. At the EAS, all 25 (100%) patients exhibited local sharp potentials (spiky potential) at the VAs, and 88% (22 of 25) individuals showed reverse late potentials in adjacent sinus beats on the bipolar mini-electrode recordings. Related unipolar electrograms manifested 20% "q-plateau-QS," 76% "gross QS," and 4% "late QS" patterns related to spiky potential voltages and advanced times. Compared with electrograms recorded by ablation catheter, bipolar mini-electrode recordings exhibited significantly shorter spiky potential durations (P = 0.001) and a significantly increased incidence of the reverse late potentials (P = 0.041). Unipolar mini-electrode recordings had a lower incidence ratio of "late QS" patterns (P = 0.039). Compared with ablation catheter mapping, mini-electrodes improved the mapping resolution of the EAS of RVOT VAs and exhibited shorter spiky potential durations and reduced incidence of "later QS" unipolar patterns.

Spiky electric and magnetic field structures in flux rope experiments

Magnetic flux ropes are structures that are common in the corona of the sun and presumably all stars. They can be thought of as the building blocks of solar structures. They have been observed in Earth's magnetotail and near Mars and Venus. When multiple flux ropes are present magnetic field line reconnection, which converts magnetic energy to other forms, can occur when they collide. The structure of multiple magnetic ropes, the interactions between multiple ropes, and their topological properties such as helicity and writhing have been studied theoretically and in laboratory experiments. Here, we report on spiky potential and magnetic fields associated with the ropes. We show that the potential structures are chaotic for a range of their temporal half-widths and the probability density function (PDF) of their widths resembles the statistical distribution of crumpled paper. The spatial structure of the magnetic spikes is revealed using a correlation counting method. Computer simulation suggests that the potential structures are the nonlinear end result of an instability involving relative drift between ions and electrons.

The exact wavefunction factorization of a vibronic coupling system

We investigate the exact wavefunction as a single product of electronic and nuclear wavefunction for a model conical intersection system. Exact factorized spiky potentials and nodeless nuclear wavefunctions are found. The exact factorized potential preserves the symmetry breaking effect when the coupling mode is present. Additionally nodeless wavefunctions are found to be closely related to the adiabatic nuclear eigenfunctions. This phenomenon holds even for the regime where the non-adiabatic coupling is relevant, and sheds light on the relation between the exact wavefunction factorization and the adiabatic approximation.

Magnetic dipole discharges. III. Instabilities

Instabilities in a cross-field discharge around a permanent magnet have been investigated. The permanent magnet serves as a cold cathode and the chamber wall as an anode. The magnet is biased strongly negative and emits secondary electrons due to impact of energetic ions. The electrons outside the sheath are confined by the strong dipolar magnetic field and by the ion-rich sheath surrounding the magnet. The electron energy peaks in the equatorial plane where most ionization occurs and the ions are trapped in a negative potential well. The discharge mechanism is the same as that of cylindrical and planar magnetrons, but here extended to a 3-D cathode geometry using a single dipole magnet. While the basic properties of the discharge are presented in a companion paper, the present focus is on various observed instabilities. The first is an ion sheath instability which oscillates the plasma potential outside the sheath below the ion plasma frequency. It arises in ion-rich sheaths with low electron supply, which is the case for low secondary emission yields. Sheath oscillations modulate the discharge current creating oscillating magnetic fields. The second instability is current-driven ion sound turbulence due to counter-streaming electrons and ions. The fluctuations have a broad spectrum and short correlation lengths in all directions. The third type of fluctuations is spiky potential and current oscillations in high density discharges. These appear to be due to unstable emission properties of the magnetron cathode.

Mutual influence of locality and chaotic dynamics on quantum controllability

Quantum control tasks are classified either as classical-like or as quantum requiring interference of pathways. We study the generation of interference pathways and relate them to the fidelity of the control target at a fixed time for various tasks. The model drift Hamiltonian studied is the two-dimensional Henon-Heiles (HH) potential. This system shows regular classical dynamics for low energies and chaotic dynamics for higher energies. A control operator supported by the whole momentum space and therefore connecting the entire Hilbert phase space is a random spiky potential. The other extreme is a smooth control potential. Intermediate cases are obtained by filtering the random spiky potential in momentum space. The fidelity of achieving a control task was related to the connectivity in phase space of the control operators. Typical quantum tasks such as generating a superposition of generalized coherent states rely on interfering pathways. For these cases the nonlinearity in the drift or control Hamiltonian is a necessary requirement for creating interferences. Control over rapidly diverging components of the wave function is achieved by the use of highly nonlocal control operators. Quantum control under chaotic drift was found to give a better yield than control under regular dynamics for such cases. For classical tasks we study the transformation of an initial generalized coherent state to another one. The best fidelity is obtained for regular or harmonic regions of the potential and smooth control operators. The approach to the classical limit is checked by decreasing the effective value of $\ensuremath{\hbar}$. Control under both quantum and classical tasks suffered from the decrease of $\ensuremath{\hbar}$ and the approach to classical proximity. Classical control tasks which rely heavily on maintaining a generalized coherent state throughout the evolution were found to be dysfunctional and lead to a completely uncontrolled situation once the classical chaos starts to appear.

A case of typical atrial flutter causing unexpected advanced atrioventricular block despite lateral cavotricuspid isthmus ablation

Here, we report a case of a 69-year-old patient with paroxysmal atrial fibrillation and inducible typical atrial flutter who required catheter ablation. After pulmonary vein isolation, cavotricuspid isthmus ablation was performed. During ablation at a lateral site of the cavotricuspid isthmus, a spiky potential appeared at the distal electrode of the ablation catheter, and subsequently, a 2:1 atrioventricular (AV) block occurred. Radiofrequency (RF) delivery at the same site caused a similar phenomenon, implying that the spiky potential may reflect a slow pathway potential as an anatomical variant of the rightward extension of the AV node.

Clinical and Electrophysiological Difference Between Idiopathic Right Ventricular Outflow Tract Arrhythmias and Pulmonary Artery Arrhythmias

The precise incidence and characteristics of ventricular arrhythmias originating from the pulmonary artery have not been fully described. The purpose of this prospective study was to clarify these points. Thirty-three consecutive patients with an idiopathic left bundle branch block and inferior-axis deviation type ventricular arrhythmia were included. All patients underwent detailed electroanatomical mapping (CARTO, Biosense-Webster, Diamond Bar, CA, USA) during sinus rhythm prior to the catheter ablation. The precise location of the catheter tip at the successful ablation site was confirmed by both electroanatomical mapping and contrast radiography. The clinical and electrophysiological data were compared between the right ventricular outflow tract (RVOT) arrhythmia patients (RVOT group) and PA arrhythmia patients (PA group). Eight patients (8/33 patients: 24.2%) had their ventricular arrhythmias successfully ablated within the PA. The local bipolar electrogram at the successful ablation sites in the PA group exhibited a significantly greater duration (P < 0.05) and lower amplitude (P < 0.05) than did those in the RVOT group (n = 19). In the PA group, all patients exhibited a multicomponent electrograms composed of a spiky potential and a dull potential, which might have consisted of near-field PA activation and a far-field ventricular activation, respectively, at the successful ablation site. Direct ablation to the spiky electrogram was able to eliminate the arrhythmias in all the PA group patients. PA arrhythmias may be more common than previously recognized. Careful mapping and interpretation of low amplitude and multicomponent electrograms are important for recognizing ventricular arrhythmias originating from the PA.

Baroreflex sensitivity normalization after cardiac resyncronization therapy: A case report

from left axis deviation with right bundle branch block (VT1) to right axis deviation with right bundle brunch block (VT2) during RF energy delivery. Cycle length of the VT2 was longer than VT1 by 20 msec. Both presystolic Purkinje potential preceding the onset of QRS complex by 50 msec and diastolic potential of preceding the onset of QRS complex158 msec were recorded at the same site during VT2. Furthermore, a spiky potential following QRS complex was also reproducibly recorded during sinus rhythm. On the basis of QRS configuration of VT2, VT2 was suspected to originate from left anterior fascicle. However, we could not find earliest Purkinje potential or diastolic potential from left anterior fascicular area. The earliest Purkinje potential activation during VT2 was located at the proximal portion of left posterior fascicle. The VT2 was terminated 10 sec after RF energy application at that site during VT2 and no longer inducible. Thus, the mechanism of VT2 was VT originating from left posterior fascicle with distal block and shift of the exit site to left anterior fascicle.