Taquicardias paroxísticas supraventriculares y síndromes de preexcitación

Anatomy for ablation of atrioventricular nodal reentry tachycardia and accessory pathways

The atrioventricular (AV) valve plane and the central septum are of particular importance for electrophysiological diagnosis and interventional therapy of supraventricular tachycardias because accessory electrical connections of various types may be present in addition to the specific conduction system. Although modern 3D electroanatomic reconstruction systems including high-density mapping can be of great assistance, detailed knowledge of the anatomic structures involved, their complex three-dimensional arrangement, and their electrical properties in conjunction with electrophysiological features of supraventricular arrhythmias is essential for safe and efficient electrophysiological treatment. The aim of this article is to present current anatomical, topographical, and electrophysiological findings against the background of historical, seminal, and still indispensable literature.

SUPRAVENTRICULAR TACHYCARDIA CLASSIFICATION USING ATTENTION-BASED RESIDUAL NETWORKS

Atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) are two common arrhythmias with high similarity. Automatic electrocardiogram (ECG) detection using machine learning and neural networks has replaced manual detection, but few studies distinguishing AVNRT from AVRT have been reported. This study proposed a classification algorithm using bottleneck attention module (BAM)-based deep residual network (ResNet) through two-lead ECG records. Specifically, ResNet possessed sufficient network depth to extract abundant features, and BAM was introduced to optimize weight assignment of feature maps by fusing together channel and spatial information. Seven types of ECG signals from four public databases were used to pretrain the proposed classification model, which was then fine-tuned using the experimental dataset. The AVNRT and AVRT detection precisions were 98.95% and 87.47%, sensitivities were 87.52% and 98.58%, and the [Formula: see text]1-scores were 92.82% and 92.68%, respectively. These findings showed that our proposed classification model achieved excellent inter-patient classification performance and can assist doctors in the diagnosis of AVNRT and AVRT.

Universal mechanisms for self-termination of rapid cardiac rhythm

Excitable media sustain circulating waves. In the heart, sustained circulating waves can lead to serious impairment or even death. To investigate factors affecting the stability of such waves, we have used optogenetic techniques to stimulate a region at the apex of a mouse heart at a fixed delay after the detection of excitation at the base of the heart. For long delays, rapid circulating rhythms can be sustained, whereas for shorter delays, there are paroxysmal bursts of activity that start and stop spontaneously. By considering the dependence of the action potential and conduction velocity on the preceding recovery time using restitution curves, as well as the reduced excitability (fatigue) due to the rapid excitation, we model prominent features of the dynamics including alternation of the duration of the excited phases and conduction times, as well as termination of the bursts for short delays. We propose that this illustrates universal mechanisms that exist in biological systems for the self-termination of such activities.

Bmal1 regulates circadian expression of cytochrome P450 3a11 and drug metabolism in mice

Metabolism is a major defense mechanism of the body against xenobiotic threats. Here we unravel a critical role of Bmal1 for circadian clock-controlled Cyp3a11 expression and xenobiotic metabolism. Bmal1 deficiency decreases the mRNA, protein and microsomal activity of Cyp3a11, and blunts their circadian rhythms in mice. A screen for Cyp3a11 regulators identifies two circadian genes Dbp and Hnf4α as potential regulatory mediators. Cell-based experiments confirm that Dbp and Hnf4α activate Cyp3a11 transcription by their binding to a D-box and a DR1 element in the Cyp3a11 promoter, respectively. Bmal1 binds to the P1 distal promoter to regulate Hnf4α transcriptionally. Cellular regulation of Cyp3a11 by Bmal1 is Dbp- and Hnf4α-dependent. Bmal1 deficiency sensitizes mice to toxicities of drugs such as aconitine and triptolide (and blunts circadian toxicity rhythmicities) due to elevated drug exposure. In summary, Bmal1 connects circadian clock and Cyp3a11 metabolism, thereby impacting drug detoxification as a function of daily time.

Hospitalization rate of paroxysmal supraventricular tachycardia in Sweden

INTRODUCTION

The hospitalization rate of paroxysmal supraventricular tachycardia (PSVT) in a nationwide study is not established. We determined age- and sex-specific hospitalization rates and time trends for hospitalized PSVT in the Swedish population between 1987 and 2010.

METHODS

This nationwide study is based on the Swedish Hospital Discharge Register. The patients with first PSVT diagnoses between January 1987 and December 2010 were identified.

RESULTS

A total of 42,765 individuals with PSVT were diagnosed (mean age 60 years; 44% males). The overall age- and sex-adjusted hospitalization rate was 20 per 100,000 person-years. The hospitalization rate increased with advancing age with highest hospitalization rates in individuals aged 80-84 years (67.12 per 100,000 person-years) and did not change significantly over time. A total of 20,011 (46.8%) patients had "lone" PSVT without any comorbidities. Lone PSVT patients were younger than PSVT patients with comorbidities (mean age 54 vs. 67 years, p = .0002).

CONCLUSIONS

This study showed a slight preponderance for females and stable hospitalization rate of PSVT over time; the hospitalization rate increased with age. A high proportion of PSVT patients had no comorbidities. They were affected at a younger age than patients with comorbidities, which suggests an inherent predisposition. Key messages This study represents the first extensive and nationwide hospitalization study of PSVT. Hospitalization is highest in old age but a bimodal pattern was observed with a small peak in the first years of life. Patients with lone PSVT are younger than those with comorbidities; which suggests an inherent predisposition.

Supraventricular Tachycardia During Status Epilepticus in Dravet Syndrome: A Link Between Brain and Heart?

BACKGROUND

The possibility that epileptic seizures and arrhythmias are different clinical manifestations of a common channelopathy is an interesting but unproved hypothesis. Patients with Dravet syndrome show heart rate variability and affected individuals with arrhythmias have also been documented. The possibility that a genetic mutation affecting sodium channel functions may predispose to both Dravet syndrome and arrhythmogenic disorders is an interesting hypothesis.

PATIENT PRESENTATION

We describe a 5-month-old girl with Dravet syndrome who presented with paroxysmal supraventricular tachycardia during status epilepticus. She presented to the hospital the first time with afebrile tonic-clonic seizures and then several subsequent times with status epilepticus confirmed with electroencephalography. During two of these episodes she also exhibited paroxysmal supraventricular tachycardia. She received propofol for status epilepticus and adenosine for the arrhythmia. A clinical and genetic (denovo mutation of a sodium channel, SCN1A) diagnosis of Dravet syndrome was made.

CONCLUSIONS

Our patient supports the hypothesis that SCN1A mutation might have a role as a common substrate to both epilepsy and cardiac arrhythmia. More studies are needed to better assess genetic, cardiac, respiratory, and autonomic dysfunction in patients with Dravet syndrome.

Use of adenosine in the treatment of supraventricular tachycardia in a pediatric emergency department

OBJECTIVE

Supraventricular tachycardia (SVT) is the most frequent arrhythmia requiring treatment in childhood, with an estimated incidence of 1/100 to 1/250 children. The treatment of choice of the acute event is intravenous adenosine. This study aimed to determine if doses of adenosine higher than previously described are needed to successfully revert SVT in children.

METHODS

This is a retrospective study of SVT cases in a tertiary hospital from January 2007 to December 2011.

RESULTS

A total of 44 episodes of SVT were recorded in 26 patients. Mean age was 3.1 years. In 39 patients (89%), adenosine was administered, reverting to stable sinus rhythm in 29 episodes, which represents an effectiveness of 75%. In relation to the number of doses administered, 12 patients (30%) received a single dose, with a mean (SD) response dose of 112 (35) µg/kg; 16 (41%) received 2 doses, with a mean (SD) response dose of 188 (55) µg/kg; and 9 (24%) received 3 doses, with a mean (SD) response dose of 249 (108) µg/kg. Finally, in 2 patients (4%), 4 doses of adenosine were administered, with only 1 of them responding to a dose of 300 µg/kg. The mean (SD) dose that reverted the SVT to normal sinus rhythm was 173 (84) µg/kg, and the mean (SD) number of doses administered was 1.7 (0.8) (range, 1-4). Sixty-six percent were discharged home, without the need to be transferred to pediatric intensive care unit or pediatric ward.

CONCLUSIONS

Most of the patients with SVT episodes require treatment with more than 1 dose of adenosine. Doses higher than the usually described in the guidelines are necessary to revert SVT. Most patients can be discharged home from the emergency department, without the need of hospital admission.