BACKGROUND: Tachycardia is a common arrhythmia in clinical practice, and its pathogenesis is mostly related to reentry. However, there are also a few tachycardia that are not related to reentry. Actively clarifying the pathogenesis of these non-reentry related tachycardia is of great significance for its treatment.
METHODS: A 55-year-old female patient presented with recurrent palpitations with a fastest heart rate of 180 beats/minute 10 years ago.
METHODS: Dual atrioventricular nodal non-reentrant tachycardia (DAVNNT).
METHODS: DAVNNT can be cured by radiofrequency ablation of atrioventricular nodal slow path modification.
RESULTS: The tachycardia has stopped.
CONCLUSIONS: DAVNNT is a rare disease in clinical practice. Its characteristic is not reentration-related arrhythmias, but the phenomenon of increased heart rate caused by electrical conduction down the double pathway of atrioventricular nodal tract and subsequent pathway. Electrophysiological examination helps to clarify the diagnosis and pathogenesis, and catheter ablation can cure the disease.

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Maternal autoimmune disease is the most common cause of congenital heart block (CHB), a rare illness characterized by fibrosis and calcification of the fetal atrioventricular (AV) node due to maternal autoantibodies anti-SSA/Ro and anti-SSB/La. We report the full autopsy and clinical information on a female neonate with high degree AV block and calcification in the AV node, atrial approaches to the AV node, and both right and left bundle branches, born to a 27-year-old female with subclinical autoimmune disease.

Ivabradine reduces the heart rate by selectively inhibiting the If current of the sinoatrial node, mainly for the treatment of chronic heart failure with decreased left ventricular systolic function and inappropriate sinus tachycardia, but the inhibitory effect on the atrioventricular node is rarely reported. The patient was admitted to hospital mainly because of intermittent chest pain for 7 years, which worsened for 10 days. Admission electrocardiogram (ECG) considered sinus tachycardia, with QS wave and T wave inversion in II, III, aVF, V3 R-V5 R, V4 -V9 leads, and non-paroxysmal junctional tachycardia (NPJT) with interference atrioventricular dissociation. After treatment with ivabradine the ECG returned to normal conduction sequence. NPJT with interference atrioventricular dissociation is a fairly rare electrocardiographic phenomenon. This case reports for the first time that ivabradine is used in the treatment of NPJT with interference atrioventricular dissociation. It is speculated that ivabradine has a potential inhibitory effect on the atrioventricular node.

Though uncommon, puncture injury to the heart can occur during cardiac resuscitation and when inserting a lifesaving drug directly into the left ventricle of the heart. Utmost precaution must be taken to avoid damaging the conduction system of the heart, particularly the nodal part, as it can cause cardiogenic shock, arrhythmia, and sudden death. Our index case report describes a 55-year-old male who was fatally injured after being hit by a truck while riding his bike. The autopsy revealed multiple puncture injuries to the atrioventricular node area of the septum, observed on both sides of the interatrial septal wall surface. Histopathological examination also showed subendocardial hemorrhage around the atrioventricular nodal area. The nature of the injuries made identification of the cause of death difficult.

Atrial premature contractions (PACs) that block at the atrio-ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing.

Left bundle branch area pacing (LBBAP) is an alternative to right ventricular (RV) and biventricular (BiV) pacing in patients scheduled for pace and ablate treatment strategy. However, current delivery sheaths are designed for left-sided implantation, making the right-sided LBBAP lead implantation challenging.
We report a case of a right-sided LBBAP approach via right subclavian vein in a heart failure patient with a persistent left superior vena cava scheduled for pace and ablate treatment of refractory atrial flutter. To enable adequate lead positioning and support for transseptal screwing, the delivery sheath was manually modified with a 90-degree curve at the right subclavian vein and superior vena cava junction to allow right-sided implantation. The distance between the reshaping point and the presumed septal region was estimated by placing the sheath on the body surface under fluoroscopy. With the reshaping of the delivery sheath, we were able to achieve LBBAP with relatively minimal torque. Radiofrequency ablation of the atrioventricular node was performed the next day and the pacing parameters remained stable in short-term follow-up.
With the modification of currently available tools, LBBAP can be performed with the right-sided approach.

A 70-year-old man with severe valvular cardiomyopathy, permanent atrial fibrillation (AF) with a slow ventricular response, and transient atrioventricular (AV) block, was admitted to our center for severe heart failure and recurrent presyncope. While hospitalized, the coronary computed tomography angiography (CTA) showed huge atriums. We tried His bundle pacing (HBP). HB potential was observed at site A, and the His-ventricular (HV) interval was 68 ms. The duration from the stimulus signal to the onset of paced QRS (S-QRSonset) at site A was 232 ms when pacing at 60 beats per minute (BPM) with the pacing threshold of 2.0 V/0.5 ms. The S-QRSonset was longer than the HV interval and had a notable and progressive prolongation from 252 ms to 456 ms during the pacing at 90 BPM. Then, we pushed another lead a little forward, and the S-QRSonset shortened back to 68 ms, and the paced QRS morphology was the same as the intrinsic QRS morphology with the pacing threshold of 1.5 V/0.5 ms. The progressively prolonged S-QRSonset demonstrated a Wenckebach phenomenon (WP), a well-known electrophysiological characteristic of the AV node (AVN). It is the first time to report an intraoperative AVN-pacing related-WP in a patient with persistent AF. The enlarged atrium might be convenient for capturing the AVN. There are some other potential explanations for this phenomenon. The diameters of atriums decreased significantly, and the symptoms improved after the procedure. This is the first reported case in which we might achieve AVN capture in a patient with persistent AF. Although we ultimately chose HBP for better long-term pacing thresholds, the result of this case suggested that AVN pacing may be possible.

Although uncommonly encountered, dual atrioventricular nodal non-reentrant tachycardia (DAVNNRT) is a well-described arrhythmia that can manifest in patients with dual atrioventricular nodal pathways physiology. This arrhythmia is characterized on electrocardiogram (ECG) by a single P wave followed by two conducted QRS complexes (so-called \"double fire\"), and on intracardiac electrograms by a single atrial electrogram followed by two separate His deflections and ventricular electrograms.
We report a rare case of \"triple-fire\" atrioventricular non-reentrant tachycardia in which a patient was found to have three distinct atrioventricular nodal pathways and multiple triple fire responses, both on surface ECG and intracardiac electrograms.
Multiple pathways physiology and it\'s clinical ramifications are discussed.

One should assume that in silico experiments in systems biology are less susceptible to reproducibility issues than their wet-lab counterparts, because they are free from natural biological variations and their environment can be fully controlled. However, recent studies show that only half of the published mathematical models of biological systems can be reproduced without substantial effort. In this article we examine the potential causes for failed or cumbersome reproductions in a case study of a one-dimensional mathematical model of the atrioventricular node, which took us four months to reproduce. The model demonstrates that even otherwise rigorous studies can be hard to reproduce due to missing information, errors in equations and parameters, a lack in available data files, non-executable code, missing or incomplete experiment protocols, and missing rationales behind equations. Many of these issues seem similar to problems that have been solved in software engineering using techniques such as unit testing, regression tests, continuous integration, version control, archival services, and a thorough modular design with extensive documentation. Applying these techniques, we reimplement the examined model using the modeling language Modelica. The resulting workflow is independent of the model and can be translated to SBML, CellML, and other languages. It guarantees methods reproducibility by executing automated tests in a virtual machine on a server that is physically separated from the development environment. Additionally, it facilitates results reproducibility, because the model is more understandable and because the complete model code, experiment protocols, and simulation data are published and can be accessed in the exact version that was used in this article. We found the additional design and documentation effort well justified, even just considering the immediate benefits during development such as easier and faster debugging, increased understandability of equations, and a reduced requirement for looking up details from the literature.