The autonomic nervous system plays an integral role in the modulation of normal cardiac electrophysiology. This is achieved via a complex network of pre- and postganglionic sympathetic and parasympathetic fibers that synapse on extrinsic and intrinsic cardiac ganglia and ultimately directly innervate cardiac myocytes. Alterations in autonomic tone may induce changes in local cellular electrophysiology that may manifest clinically in a number of ways, ranging from changes in heart rate to changes in heart rhythm. These relationships between autonomic tone and the evolution of cardiac dysrhythmias are areas of evolving research, with increasing evidence for a key role for autonomic ganglia in the pathogenesis of atrial fibrillation and sympathetic nerves in the predilection toward ventricular tachycardia in areas of myocardial scar. In this review, we highlight what is known about the anatomy and physiology of the cardiac autonomic nervous system, the evidence supporting the relationship of autonomic tone to clinically significant arrhythmias, and a variety of mechanisms (eg, direct ion channel effects) and diagnostic tools that exist to help define this relationship. Further emphasized are potential future avenues of research needed to elucidate the relationship between changes in normal autonomic tone and the pathogenesis of cardiac arrhythmias.

Structural barriers can promote discordant action potential (AP) duration alternans, T wave alternans (TWA) and tachyarrhythmia in animal hearts and simulation studies. We hypothesized that heterogeneous scar (gray zone) and dense midwall scar (midwall core) would promote TWA in patients with cardiomyopathy by slowing conduction and uncoupling transmural APs, respectively. Scar core and gray zone were quantified in 40 cardiomyopathy patients using late gadolinium enhanced cardiac magnetic resonance imaging and related to the results of a clinically validated TWA test. The percentages of gray zone, epicardial core and midwall core were greater in the +TWA group, correlated with TWA magnitude and related to a lower heart rate onset for TWA. These specific scar patterns contribute to the genesis and severity of TWA in cardiomyopathy. Greater knowledge of the substrates that promote TWA in cardiomyopathy patients is valuable in determining those at risk of lethal ventricular arrhythmias.

Structural barriers can promote discordant action potential (AP) duration alternans, T wave alternans (TWA) and tachyarrhythmia in animal hearts and simulation studies. We hypothesized that heterogeneous scar (gray zone) and dense midwall scar (midwall core) would promote TWA in patients with cardiomyopathy by slowing conduction and uncoupling transmural APs, respectively. Scar core and gray zone were quantified in 40 cardiomyopathy patients using late gadolinium enhanced cardiac magnetic resonance imaging and related to the results of a clinically validated TWA test. The percentages of gray zone, epicardial core and midwall core were greater in the +TWA group, correlated with TWA magnitude and related to a lower heart rate onset for TWA. These specific scar patterns contribute to the genesis and severity of TWA in cardiomyopathy. Greater knowledge of the substrates that promote TWA in cardiomyopathy patients is valuable in determining those at risk of lethal ventricular arrhythmias.

We sought to determine whether spinal cord stimulation (SCS) therapy, when applied chronically to canines, imparts long-lasting cardio-protective effects on neurogenic atrial tachyarrhythmia induction and, if so, whether its effects can be attributable to i) changes in intrinsic cardiac (IC) neuronal transmembrane properties vs ii) modification of their interneuronal stochastic interactivity that initiates such pathology. Data derived from canines subjected to long-term SCS [(group 1: studied after 3-4 weeks SCS; n = 5) (group 2: studied after 5 weeks SCS; n = 11)] were compared to data derived from 10 control animals (including 4 sham SCS electrode implantations). During terminal studies conducted under anesthesia, chronotropic and inotropic responses to vagal nerve or stellate ganglion stimulation were similar in all 3 groups. Chronic SCS suppressed atrial tachyarrhythmia induction evoked by mediastinal nerve stimulation. When induced, arrhythmia durations were shortened (controls: median of 27 s; SCS 3-4 weeks: median of 16 s; SCS 5 weeks: median of 7 s). Phasic and accommodating right atrial neuronal somata displayed similar passive and active membrane properties in vitro, whether derived from sham or either chronic SCS group. Synaptic efficacy was differentially enhanced in accommodating (not phasic) IC neurons by chronic SCS. Taken together these data indicate that chronic SCS therapy modifies IC neuronal stochastic inter-connectivity in atrial fibrillation suppression by altering synaptic function without directly targeting the transmembrane properties of individual IC neuronal somata. •Spinal cord stimulation (SCS) suppresses neurally induced atrial fibrillation (AF).•Effectiveness of SCS in AF suppression increases with time.•SCS minimally impacts active and passive properties of individual intrinsic cardiac neurons.•SCS modifies synaptic efficacy of the IC network.•SCS differentially impacts the neurotransmission to the accommodating sub-population of IC neurons.

The transthoracic application of synchronized direct current cardioversion (DCC) is widely used to terminate atrial fibrillation, atrial flutter, and other supraventricular tachyarrhythmia. DCC is a highly effective method for acute restoration of sinus rhythm. Although DCC is a relatively safe and frequently performed procedure, data on potential side effects are very rarely reported in the literature. The most serious complications associated with DCC are thromboembolism and intracranial hemorrhage. The true incidence of postcardioversion pulmonary edema is not known, but it is estimated to occur in 1%to 3% of patients, particularly those with coexistent heart disease. We report on a patient with a structurally normal heart who developed acute pulmonary edema after undergoing DCC. The patient had no evidence of myocardial injury according to an electrocardiogram and cardiac biomarkers. The patient was treated with intravenous diuretics. After 4 days, the pulmonary edema resolved.

Abstract Approximately 1-2 percent of the world population lives with various heart rhythm disorders of supraventricular nature. These arrhythmias can alter the patient's lifestyle and negatively affect the balance between the demands of daily life and functional abilities. To diagnose paroxysmal supraventricular tachycardia (PSVT) can be difficult due to spontaneity of the episodes and the transience nature of the symptoms. Finding the right treatment can also pose a challenge because some of the medicines used are associated with increased toxic risks and requires close monitoring of the patient through regular blood tests. Some patients experience recurrence of symptoms despite optimal treatment measures and adherence to treatment and self-care recommendations.  Studies have shown that patients’ prior knowledge regarding these diagnoses is low. The nurse has a crucial role of informing and making sure that patients receive education in among other things self-care as well as information regarding disease and drugs related complications etc. There is a mutual interaction between daily life and functional health status where daily life makes demands on functional abilities at the same time as these affect how an individual lives their daily lives. In order to experience quality of life and health, the balance between these two must be maintained. The nurse has a pivot role in assisting the patient maintain the balance.  The study’s aim was to highlight the effects of living with supraventricular tachycardia (SVT) on the patient's daily life. The method chosen was literature review. Original articles were obtained from established databases such as PubMed and CINAHL, and the results from 17 articles were analyzed using content analysis. This means that the text was read several times in order to familiarize with the content. Different units were identified and the categories as well as sub-categories were coded. These formed the basis of the headings and subheading used to present the results. Four categories and ten sub-categories were identified from the studies.  Studies show that SVT has negative effects on the patients’ daily life. Symptoms cause anxieties and uncertainties that lead to mental and emotional stress. Some patients withdraw from participating in the social activities for fear of provoking the attacks whereas others are forced to give up participation due to among other things fatigue that results from symptoms attacks. Family life is sometimes disrupted since the symptoms can lead to fatigue that negatively affects family life in that patients do not have the energy to participate in activities in their home or to live up to other requirements of their daily lives.  The diagnosis can even affect economy since patients are forced to cut down on working hours or go into early retirement. Other patients lost their employment due to frequent hos-pital visits or inability to fulfill their duties. Physical activities as well as well-being are negatively affected too in that some patients show signs of impaired physical activities. Patients use different coping strategies such as planning their daily lives around the symp-tomatic periods. In conclusion it is suffice to state that SVT has negative effects on the patients’ daily life. The Patients would benefit from a well-structured and person centered patient education.

Ce travail a eu pour but (1) de comparer les différentes méthodes d'évaluation de la balance sympatho-vagale (BSV) actuellement utilisées chez le rat, et (2) d'évaluer les effets d'une altération de la BSV en faveur d'une prédominance vagale sur l'instabilité électrique atriale spontanée chez le rat spontanément hypertendu (SHR) vieillissant. L'électrocardiogramme a été mesuré chez les rats éveillés grâce à une sonde télémétrique chroniquement implantée. La méthode de référence pour l'estimation de la BSV repose sur le calcul du rapport de la fréquence cardiaque (FC) de repos à la FC intrinsèque. Selon que l'index est supérieur ou inférieur à 1, on peut conclure respectivement à une prédominance sympathique ou à une prédominance vagale. La FC intrinsèque est obtenue par l'administration combinée d'antagonistes sélectifs des deux branches du système nerveux autonome, c'est-à-dire un bloqueur β-adrénergique (aténolol) et un antagoniste des récepteurs muscariniques (méthylatropine). Les autres méthodes (mesure séparée des tonus autonomes, index extraits de l'analyse de la variabilité sinusale) fournissent des résultats incohérents ou contradictoires. L'administration chronique d'un inhibiteur de l'acétylcholinestérase (pyridostigmine) chez des rats SHR vieillissants induit une hypertonie vagale relative (BSV=0,81±0,02) par rapport aux rats non traités (BSV=1,06±0,01) qui s'accompagne d'une bradycardie sinusale et d'une augmentation de la fréquence et de la durée des épisodes de tachyarythmie atriale. Ces études démontrent l'intérêt de la méthode de référence pour l'estimation de la BSV chez le rat éveillé. La potentialisation de l'activité vagale endogène aggrave l'instabilité électrique atriale chez le rat SHR vieillissant, ce qui confirme le rôle pathogénique du système nerveux parasympathique dans ce modèle / The aim of the present work was (1) to compare the different methods currently used to assess sympathovagal balance (SVB) in rats, and (2) to assess SVB alterations towards vagal predominance on atrial electrical instability in aging spontaneously hypertensive rats (SHR). The electrocardiogram was measured in conscious rats using chronically implanted telemetric probes. The reference method to estimate SVB is based on the calculation of the ratio of intrinsic heart rate (HR) to resting HR. Depending on whether the index is greater or lower than 1, one can conclude to sympathetic or vagal predominance, respectively. Intrinsic HR is obtained after the combined administration of selective antagonists of both branches of the autonomic nervous system, i.e. β- adrenergic blocker (atenolol) and muscarinic receptor antagonist (methylatropine). Other methods (autonomic tones measured separately, calculation of indices derived from heart rate variability analysis) provide inconsistent or conflicting results. The chronic infusion of an acetylcholinesterase inhibitor (pyridostigmine) in aging SHRs induced relative vagal hypertonia (SVB=0.81±0.02) in comparison with untreated rats (SVB=1.06±0.01) along with sinus bradycardia and increased frequency and duration of atrial tachyarrhythmia episodes. These studies highlight the value of the reference method for evaluating SVB in conscious rats. Potentiation of endogenous vagal activity aggravates atrial electrical instability in aging SHRs, consistent with a pathogenic role of the parasympathetic nervous system in this model