Paroxysmal atrioventricular block

Association between epigenetic aging and atrioventricular block: a two-sample Mendelian randomization study

AIMS

Atrioventricular block (AVB) is a prevalent bradyarrhythmia. This study aims to investigate the causal effects of epigenetic aging, as inferred from DNA methylation profiles on the prevalence of AVB by Mendelian randomization (MR) analysis.

METHODS

Genetic instruments for epigenetic aging and AVB were obtained from genome-wide association study data in the Edinburgh DataShare and FinnGen biobanks. Univariable and multivariable MR analyses were conducted to evaluate causal associations. Additionally, we employed sensitivity tests to assess the robustness of the MR findings.

RESULTS

MR analysis showed that genetically predicted GrimAge acceleration was significantly associated with a higher risk of AVB (inverse variance-weighted: p = 0.010, 95% confidence interval (CI) = 1.024-1.196; weighted median: p = 0.031, 95% CI = 1.009-1.215). However, no evidence supported a causal relationship between AVB and epigenetic aging. The association between epigenetic aging and AVB was established using multivariate MR analysis after adjusting for various risk factors. Sensitivity analyses confirmed the reliability and robustness of the results.

CONCLUSION

Our findings suggest that epigenetic aging in GrimAge may increase the risk of AVB, emphasizing the importance of addressing epigenetic aging in strategies for AVB prevention.

Cardioneuroablation for the management of neurally mediated syncope, sinus bradycardia, and atrioventricular block

Through several decades of medical advances, we have improved our understanding of the role of the autonomic nervous system in the production of a myriad of clinical cardiac conditions such as vasovagal syncope, situational syncope, carotid sinus hypersensitivity, vagally mediated sinus bradycardia, and atrioventricular block. While typically not associated with mortality, these common clinical entities may result in significant patient symptoms and morbidity and are often characterized by a frustrating treatment course with a paucity of effective strategies. In recent years, there has been increased interest in the management of these conditions via direct modulation of the parasympathetic component of the autonomic nervous system. This is achieved by targeting the ganglionated plexus central to the pathogenesis of these conditions via cardioneuroablation. The primary role of this strategy is evolving and serves to augment traditional treatment strategies such as lifestyle modification and pharmacotherapy. In this review, we examine the principles governing the role of cardioneuroablation in select populations with vasovagal syncope, sinus dysfunction, and atrioventricular block including the evolving evidence in this exciting field while keeping in mind the need for robust clinical studies examining the long-term effectiveness and safety.

Coenzyme Q deficiency may predispose to sudden unexplained death via an increased risk of cardiac arrhythmia

Cardiac arrhythmia is currently considered to be the direct cause of death in a majority of sudden unexplained death (SUD) cases, yet the genetic predisposition and corresponding endophenotypes contributing to SUD remain incompletely understood. In this study, we aimed to investigate the involvement of Coenzyme Q (CoQ) deficiency in SUD. First, we re-analyzed the exome sequencing data of 45 SUD and 151 sudden infant death syndrome (SIDS) cases from our previous studies, focusing on previously overlooked genetic variants in 44 human CoQ deficiency-related genes. A considerable proportion of the SUD (38%) and SIDS (37%) cases were found to harbor rare variants with likely functional effects. Subsequent burden testing, including all rare exonic and untranslated region variants identified in our case cohorts, further confirmed the existence of significant genetic burden. Based on the genetic findings, the influence of CoQ deficiency on electrophysiological and morphological properties was further examined in a mouse model. A significantly prolonged PR interval and an increased occurrence of atrioventricular block were observed in the 4-nitrobenzoate induced CoQ deficiency mouse group, suggesting that CoQ deficiency may predispose individuals to sudden death through an increased risk of cardiac arrhythmia. Overall, our findings suggest that CoQ deficiency-related genes should also be considered in the molecular autopsy of SUD.

The Rate of Asystolic Reflex Syncope Is Not Influenced by Age

BACKGROUND

The head-up tilt test (HUT) and other evidence suggest that the vagal effect on the heart decreases with age.

OBJECTIVES

The main aim of the study was to assess whether this age effect also affects the rate of asystole in spontaneous reflex syncope (RS).

METHOD

We performed an analysis of pooled individual data from 4 studies that recruited patients ≥40 years of age affected by certain or suspected RS who received an implantable loop recorder (ILR) and reported follow-up data on syncope recurrence. We assessed the presence of asystolic syncope of >3 seconds or nonsyncopal asystole of >6 seconds recorded by ILR and compared the findings to tilt test results on the same patients.

RESULTS

A total of 1,046 patients received ILR because of unexplained syncope. Of these, 201 (19.2%) had a documentation of an asystolic event of 10-second (Q1-Q3: 6- to 15-second) duration. They were subdivided in 3 age tertiles: ≤60 years (n = 64), 61 to 72 years (n = 72), and ≥73 years (n = 65). The rate of asystolic events was similar in the 3 subgroups (50.1%, 50.1%, and 49.2%, respectively; P = 0.99). Conversely, the rate of asystolic syncope induced during HUT (performed in 169 of 201) was greatly age dependent (31.0%, 12.1%, and 11.1% in increasing age tertiles, respectively; P = 0.009).

CONCLUSIONS

The rate of the spontaneous asystolic form of RS documented by ILR is constant at any age >40 years. Conversely, the rate of asystolic syncope induced by HUT is higher in younger patients and decreases with age. The contrasting results between spontaneous and tilt-induced events cast doubt on the concept that asystole in RS is less common in older patients.

Definitions and Pitfalls in the Diagnosis of Atrioventricular Block

The widespread use of disparate definitions of atrioventricular block has created important diagnostic problems. Adherence to the correct definitions provides a logical and simple framework for clinical evaluation. This review focuses on the clinical importance of the definitions in the diagnosis of the various types of atrioventricular (AV) block and the associated diagnostic pitfalls.

Ventricular Arrest With a Duration of 23.8 Seconds

This case report describes a patient in their late 40s undergoing a surgical procedure and experiencing a 23.8-second ventricular asystole.

Twenty-five years of research on syncope

Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.

Tests for the identification of reflex syncope mechanism

INTRODUCTION

Treatment efficacy of reflex syncope is mainly related to the mechanism underlying syncope rather than its etiology or clinical presentation. The predominant mechanism underlying reflex syncope can be assigned to hypotensive or to bradycardic phenotypes.

AREAS COVERED

Methodology and diagnostic criteria of the most useful tests for the identification of hypotensive and bradycardic phenotypes are discussed. Diagnostic tests for the hypotensive phenotype include office blood pressure measurement with active standing test, home, and wearable blood pressure monitoring, 24-h ambulatory blood pressure monitoring and tilt table test. Diagnostic tests for the bradycardic phenotype include carotid sinus massage, tilt table test and prolonged ECG monitoring.

EXPERT OPINION

In reflex syncope, the documentation of bradycardia/asystole during a syncopal episode does not rule out the possibility that a preceding or parallel hypotensive reflex plays an important role. Similarly, even when a hypotensive mechanism is established, the possibility of an associated cardioinhibitory reflex should be investigated. Investigating the mechanism of reflex syncope is mandatory in patients with severe recurrent episodes, with the final aim to develop a personalized treatment strategy. Recent trials have demonstrated the benefits of personalized mechanism-based therapy, thus highlighting the importance of a comprehensive assessment of the mechanisms underlying syncope.

A Case of Symptomatic Paroxysmal Complete Atrioventricular Block

Paroxysmal complete atrioventricular block (PCAB) is clinically characterized by a sudden change from 1:1 atrioventricular (AV) conduction leading to complete heart block. Patients may have a vast array of symptoms, but commonly, PCAB will lead to syncope and possible sudden cardiac death. The literature currently consists of three different types of PCAB: intrinsic paroxysmal atrioventricular block, extensive vagal paroxysmal atrioventricular block, and extrinsic idiopathic paroxysmal atrioventricular block. Currently, there is no single symptom or sign that is specific to a single type of AV block. PCAB is often missed or overlooked because of its unpredictability and no evidence of conduction disease with a normal 1:1 conduction on routine electrocardiograms. Here, we present a case of a 65-year-old female who has been intermittently symptomatic for four years and was found to have PCAB.

A case report of paroxysmal complete atrioventricular block in a patient with dextrocardia and repaired tetralogy of Fallot

BACKGROUND

Some adults suffer sudden cardiac death after previous surgical repair of tetralogy of Fallot (TOF), and in such cases, ventricular tachycardia is believed to be the most frequent cause of death. However, we report a case of cardiac arrest due to paroxysmal complete atrioventricular block in an adult with dextrocardia and repaired TOF.

CASE SUMMARY

A 49-year-old woman with dextrocardia and a history of surgical treatment for TOF lost consciousness three times. A previously implanted loop recorder showed a 60-second cardiac arrest, and complete atrioventricular block was diagnosed. An electrophysiological study showed prolongation of the His-ventricular interval but no ventricular tachycardia. A dual chamber pacemaker was implanted, and there has been no recurrence of syncope in the 23 months since implantation.

DISCUSSION

There is little evidence for paroxysmal complete atrioventricular block in patients with repaired TOF. This case suggests that paroxysmal complete atrioventricular block can occur late after surgical repair of TOF, and research needs to elucidate whether it is the cause of sudden cardiac death in some patients with TOF.

Healing the Broken Hearts: A Glimpse on Next Generation Therapeutics

Cardiovascular diseases are the leading cause of death worldwide, accounting for 32% of deaths globally and thus representing almost 18 million people according to WHO. Myocardial infarction, the most prevalent adult cardiovascular pathology, affects over half a million people in the USA according to the last records of the AHA. However, not only adult cardiovascular diseases are the most frequent diseases in adulthood, but congenital heart diseases also affect 0.8–1.2% of all births, accounting for mild developmental defects such as atrial septal defects to life-threatening pathologies such as tetralogy of Fallot or permanent common trunk that, if not surgically corrected in early postnatal days, they are incompatible with life. Therefore, both congenital and adult cardiovascular diseases represent an enormous social and economic burden that invariably demands continuous efforts to understand the causes of such cardiovascular defects and develop innovative strategies to correct and/or palliate them. In the next paragraphs, we aim to briefly account for our current understanding of the cellular bases of both congenital and adult cardiovascular diseases, providing a perspective of the plausible lines of action that might eventually result in increasing our understanding of cardiovascular diseases. This analysis will come out with the building blocks for designing novel and innovative therapeutic approaches to healing the broken hearts.

Paroxysmal Atrioventricular Block: A Rare Cause of Cardiac Arrest

Paroxysmal atrioventricular block (PAVB) is characterized by a sudden and unanticipated repetitive block of atrial impulses to the ventricles. It is often triggered by supraventricular and ventricular ectopic beats in patients with diseased His-Purkinje system. We present the case of a 69-year-old woman with a history of fascicular block who was admitted with gastrointestinal bleeding. Her hospital course was complicated by cardiac arrest. At the time of the loss of consciousness, telemetry tracings showed sudden onset high-grade second-degree atrioventricular (AV) block with a delayed escape rhythm resulting in a prolonged pause. Adult cardiac life support was necessary along with transvenous pacing until she ultimately underwent the placement of a permanent pacemaker. Thorough evaluation of electrocardiograms (EKGs) and telemetry allowed for accurate diagnoses and appropriate treatment of cardiac arrest secondary to paroxysmal AV block.

ESC-Leitlinien 2021 zur Herzschrittmacher- und kardialen Resynchronisationstherapie – Systemwahl

Die neuen ESC-Leitlinien haben gegenüber den vorherigen Leitlinien die Systematik teilweise verändert, kommen aber bei den herkömmlichen Schrittmacherindikationen und der hieraus abgeleiteten Systemwahl zu vergleichbaren Ergebnissen. Als Standardoption wird bei allen Patienten ohne Vorhofflimmern ein Zweikammer-Schrittmacher (DDD) empfohlen. Dabei wird gefordert, durch ein AV-Management (AVM) die ventrikuläre Impulsabgabe möglichst zu minimieren. Bei den erweiterten Indikationen im Bereich der AV-Blockierungen und Reizleitungsstörungen entsteht dagegen durch die stärkere Berücksichtigung der kardialen Resynchronisationstherapie (CRT) und der Neuaufnahme der His-Bündel-Stimulation (HBP) ein sehr viel komplexeres Bild der Therapiemöglichkeiten. Bei Patienten mit Herzinsuffizienz und eingeschränkter LV-Funktion (HFrEF) wird bei verbreitertem QRS-Komplex (> 130 ms), vor allem bei Linksschenkelblock-Morphologie, die Implantation eines CRT-Systems empfohlen. Erstmals wurde die His-Bündel-Stimulation für Patienten, bei denen eine Koronarsinuselektrode nicht erfolgreich zu platzieren ist, und für Patienten mit einer LVEF > 40% und über 20% ventrikuläre Stimulation in die Leitlinien aufgenommen.

Prevalence and Clinical Characteristics of Patients with Pause-Dependent Atrioventricular Block

Background: In patients with complete atrioventricular block (AVB), the prevalence and clinical characteristics of patients with pause-dependent AVB (PD-AVB) is not known. Our objective was to assess the prevalence of PD-AVB in a population of patients with complete (or high-grade) AVB. Methods: Twelve-lead electrocardiogram (ECG) and/or telemonitoring from patients admitted (from September 2020 to November 2021) for complete (or high-degree) AVB were prospectively collected at the University Hospital of Nice. The ECG tracings were analyzed by an electrophysiologist to determine the underlying mechanism of PD-AVB. Results: 100 patients were admitted for complete (or high-grade) AVB (men 55%; 82 ± 12 years). Arterial hypertension was present in 68% of the patients. Baseline QRS width was 117 ± 32 ms, and mean left ventricular ejection fraction was 56 ± 7%. Fourteen patients (14%) with PD-AVB were identified, and presented similar clinical characteristics in comparison with patients without PD-AVB, except for syncope (which was present in 86% versus 51% in the non-PD-AVB patients, p = 0.01). PD-AVB sequence was induced by: Premature atrial contraction (8/14), premature ventricular contraction (5/14), His extrasystole (1/14), conduction block in a branch (1/14), and atrial tachycardia termination (1/14). All patients with PD-AVB received a dual-chamber pacemaker during hospitalization. Conclusion: The prevalence of PD-AVB was 14%, and may be underestimated. PD-AVB episodes were more likely associated with syncope in comparison with patients without PD-AVB.

Paroxysmal atrioventricular block induced during paroxysmal intra-atrial reentrant tachycardia

Paroxysmal atrio-ventricular (AV) block is a relatively rare form of bradyarrhythmia that may be caused by vagal reflex, intrinsic His-Prukinje system (HPS) disorder, or idiopathic mechanisms. We report a case with paroxysmal AV block and syncopal episodes that appeared only during intra-atrial reentrant tachycardia (IART) after an ablation procedure. Syncope did not occur under sinus rhythm with stable 1:1 AV conduction. An HPS disorder was proven in an electrophysiological study. It was suggested that paroxysmal AV block was induced via a tachycardia-dependent mechanism with an exacerbation of latent HPS disorder. The occurrence of the IART was only transient, and there was no recurrent syncope during one-year follow-up. Pacemaker implantation could be avoided. <Learning objective: Paroxysmal atrio-ventricular block is a relatively rare form of bradyarrhythmia and can occur only during atrial tachyarrhythmia. Indications for a cardiac implantable electrical device should be carefully considered if the attributed tachycardia is treatable.>.

Cardioneuroablation for Treatment of Atrioventricular Block

[Figure: see text].

How Cardiac Embryology Translates into Clinical Arrhythmias

The electrophysiological signatures of the myocardium in cardiac structures, such as the atrioventricular node, pulmonary veins or the right ventricular outflow tract, are established during development by the spatial and temporal expression of transcription factors that guide expression of specific ion channels. Genome-wide association studies have shown that small variations in genetic regions are key to the expression of these transcription factors and thereby modulate the electrical function of the heart. Moreover, mutations in these factors are found in arrhythmogenic pathologies such as congenital atrioventricular block, as well as in specific forms of atrial fibrillation and ventricular tachycardia. In this review, we discuss the developmental origin of distinct electrophysiological structures in the heart and their involvement in cardiac arrhythmias.

Heart Failure due to High Degree Atrio-Ventricular Block: How Frequent is it and what is the cause?

BACKGROUND

The causes of heart failure (HF) during high-grade atrio-ventricular block (AVB) are poorly understood. This study assessed the mechanisms of HF in patients with AVB.

METHODS

We studied patients presenting (over the period 2012-2016) with high-grade AVB not related to acute myocardial infarction (MI). Patients with preexisting significant valvular heart disease were excluded. All patients underwent comprehensive echocardiographic evaluation during AVB, prior to pacemaker implantation. The diagnosis of HF was based on the Framingham criteria.

RESULTS

122 patients were included in the study, 50% male, average age 76+/-13 years. Twenty-eight (23%) patients with AVB presented with HF. Univariate correlates associated with HF were decrease in cardiac output (CO) [0.67 (95% confidence interval 0.49-0.9) per liter/min, p=0.007], measures of impaired left ventricular (LV) compliance and increase in diastolic mitral regurgitation (MR) volume [1.04 (1.01- 1.07), per cc, p=0.0016]. Ventricular rate during AVB and left-ventricular ejection fraction (LVEF) were not significantly associated with the presence of HF. By multivariate nominal logistic analysis, the best model associated with HF included diastolic MR volume [OR 1.03 (1.00-1.07), p=0.03], A-wave deceleration time [OR 0.96 (0.94-0.98), p=0.001], and CO [OR 0.72 (0.48-1.00), p=0.05], (X²= 30.6; AUC 0.84; p<0.0001 for the entire model).

CONCLUSIONS

In the setting of high-degree AVB, clinical HF occurrence correlates with impaired LV compliance and diastolic MR volume, but not with heart rate or LVEF. The cardiac performance of patients with poor LV compliance and high-volume diastolic MR may show maladjustment to slow heart rates, manifesting as low CO and HF.

Sudden unexpected improvement in the atrioventricular conduction. What is the mechanism?

The 12-lead electrocardiogram (ECG) of a 79-year-old male patient with recurrent pre-syncope showed irregular sinus rhythm with constant PR interval and left bundle branch block (LBBB) with intermittently blocked P waves. The beat following the blocked P wave had a narrower QRS with a shorter PR interval. The phenomenon of bilateral bundle branch block explains the sudden improvement in the atrioventricular conduction.

Adenosine and neurohumoral syncope

Either central or peripheral baroreceptor reflex abnormalities and/or alterations in neurohumoral mechanisms play a pivotal role in the genesis of neurally mediated syncope. Thus, improving our knowledge of the biochemical mechanisms underlying specific forms of neurally mediated syncope (more properly termed 'neurohumoral syncope') might allow the development of new therapies that are effective in this specific subgroup. A low-adenosine phenotype of neurohumoral syncope has recently been identified. Patients who suffer syncope without prodromes and have a normal heart display a purinergic profile which is the opposite of that observed in vasovagal syncope patients and is characterized by very lowadenosine plasma level values, low expression of A2A receptors and the predominance of the TC variant in the single nucleotide c.1364 C>T polymorphism of the A2A receptor gene. The typical mechanism of syncope is an idiopathic paroxysmal atrioventricular block or sinus bradycardia, most often followed by sinus arrest. Since patients with low plasma adenosine levels are highly susceptible to endogenous adenosine, chronic treatment of these patients with theophylline, a non-selective adenosine receptor antagonist, is expected to prevent syncopal recurrences. This hypothesis is supported by results from series of cases and from two controlled studies.

Five cases of complete atrioventricular block induced by bending forward: unusual but not unique

AIMS

We describe five patients with syncope caused by a complete atrioventricular block (AVB) while they were bending forward, not rising after bending, and aim to describe the occurrence and the association between bending forward and AVB.

METHODS AND RESULTS

In two patients, bending forward was the exclusive trigger for syncope, while in the remaining three, other postural changes (sitting down, standing up, and exertion) could also provoke syncope. Complete AVB as the cause of syncope was documented using ECG monitoring in two cases and an implantable loop recorder in the other three. Ectopic beats without preceding sinus slowing occurred before syncope in four cases. Two cases had a left bundle branch block. All patients responded favourably to cardiac pacing.

CONCLUSION

This is the first case series on complete AVB provoked by bending forward. Syncope during bending forward should suggest a search for an AVB. Arguments in favour of a vagal mechanism were syncope triggered by bending forward, and that other triggers could also evoke syncope. However, the absence of sinus slowing before syncope in some cases and the fact that bending forward did not seem to provoke reflex syncope without AVB, cast doubts on a reflex mechanism. There were also arguments favouring conduction disorder: i.e. ectopic beats before syncope and pre-existing conduction disturbances in two cases. The cases are reminiscent of paroxysmal AVB. Discrimination between paroxysmal AVB and vagal AVB is important because a pacemaker is warranted in arrhythmic complete AVB, while the benefit is limited or absent in reflex AVB.

Neurologic complications of brady-arrhythmias

Brady-arrhythmias are responsible for both overt as well as subtle neurologic signs and symptoms, from the seemingly benign and nonspecific symptoms associated with presyncope, to sudden focal neurologic deficits. A brief background on nodal and infra-nodal brady-arrhythmias is provided, followed by extensive discussion regarding neurologic complications of brady-arrhythmias. The multiple mechanisms of and associations between Brady-arrhythmias and transient ischemic attacks and ischemic stroke are discussed. Controversial associations between brady-arrhythmias and neurologic disease are discussed as well, such as potential roles of brady-arrhythmias in cognitive impairment and sequelae of chronotropic incompetence; and the contribution of brady-arrhythmias to syncope and associated injuries to the nervous system. The chapter is written to stand on its own, with guidance toward other pertinent sections of this text where appropriate for further reading.

Reflex Atrioventricular Block

Reflex atrioventricular block is well-recorded although it is considered rare. Recent data suggests that it is less rare than has been supposed. It has been shown to occur in both vasovagal and carotid sinus reflexes. It has to be distinguished from paroxysmal atrioventricular block due to ventricular conduction tissue disease. Low chronic adenosine levels combined with adenosine release may mimic reflex atrioventricular block. Explanations of the mechanism of these phenomena have been lacking until the recent past. The relevance of reflex atrioventricular block to clinical decision-making is as a possible indication for pacing the heart with consideration given to the vasodepressor component of the reflex.

Vagal-induced Complete Heart Block during Coronary Angiography due to Bladder Distention

Vagal stimulation is common during angiographic procedures. A vasovagal reaction in the setting of coronary angiography most commonly presents as hypotension and/or bradycardia. While the array of signs and symptoms of vasovagal reactions are known, atrioventricular (AV) block maybe overlooked due to its intermittent nature. Below we describe a case of a 47 year-old female who presented with transient complete AV block, mediated by a vagal reaction due to bladder distention in the setting of an invasive coronary angiography procedure.

What is the mechanism of paroxysmal atrioventricular block in a patient with recurrent syncope?

Paroxysmal atrioventricular (AV) block is characterized by sudden appearance of complete heart block with no escape rhythm. Three types have been described having different mechanisms namely, vagally mediated, intrinsic, and idiopathic. A rare case scenario is being described with the occurrence of paroxysmal AV block of all three types in the same patient.

Syncope due to unexpected paroxysmal sinus arrest

We present two cases with unexpected long sinus arrest resulting in syncope. There were no signs or symptoms of either sick sinus syndrome or increased vagal tone before the occurrence of pauses in these patients. The fact that these patients remained asymptomatic for quite long shows striking resemblance to paroxysmal sub-AV nodal block. We would therefore prefer to classify these cases as paroxysmal sinus arrest as a possible manifestation of the sick sinus syndrome.

Fortuitous Identification of Fluctuating AV Block: A Case Report

BACKGROUND

Vagally mediated atrioventricular block (AVB) may occur as a result of increased parasympathetic tone. This particular AVB is infrequently described in the literature, but its prevalence may be underestimated, as it may occur without recognition.

CASE REPORT

We present a case of vagally mediated AVB that was identified by serial electrocardiography of a patient who presented to the emergency department with vomiting. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Vagally mediated AVB must be differentiated from paroxysmal, bradycardia-dependent AVB, which may progress to persistent AVB and require pacemaker placement. In an asymptomatic patient with vagally mediated AVB, pacemaker placement is contraindicated. However, if symptoms are clearly attributable to vagally mediated AVB, pacemaker placement may be reasonable.

Challenges in Bradicardias Interpretation

Sinus node dysfunction or atrioventricular blocks are the causes of bradycardias. Diagnosis and management begin with evaluation of patient's hemodynamic status and diagnosis of bradycardia's cause. This is followed by an in depth evaluation of pathophysiology of the arrhythmia, its severity, and likelihood of progression. Implementing emergent measures depends on the presence of subsidiary pace makers maintaining cardiac output. Many of these decisions are greatly helped by 12 lead electrocardiogram, because its tracings are often diagnostic of the cause of the bradycardia and help to assess its persistence and progression and to evaluate the presence and reliability of subsidiary pacemakers.

Electrocardiographic Approach to Complex Arrhythmias: P, QRS, and Their Relationships

When faced with an electrocardiographic recoding of a complex arrhythmia, we often use inflexible algorithms or try to recall patterns already seen, which is often insufficient to explain the mechanisms of difficult bradycardias and tachycardias. We propose an approach to these situations where, starting from basic observations, the behavior of the different components of the arrhythmia is reconstructed using logical deductions. The extensive use of laddergrams faithfully illustrates how analysis of timing of each visible event, P and QRS, clarifies their relationship and dictates the behavior of electrocardiographic silent cardiac structures (sinus node and atrioventricular node).

Cardiogenic anorexia and underweighting in a child: case report

Introduction

In this case, we present a child with a diagnosis of anorexia and no known cardiac disease, who was referred to our clinic for a routine cardiac monitoring. ‘Asymptomatic’ high degree of atrioventricular block (AVB) was revealed. She underwent successful pacemaker (PM) implantation and losing of the weight stopped.

Case presentation

In this case, the abrupt AVB with more than 6 s ventricular pauses without escape rhythm during the day-time most possible is a type of neurally mediated AVB which was presented by anorexia, underweighting, and refusing to eat in a 12-year-old girl. All symptoms disappeared after PM implantation, and weight gain was recorded during 6 months of follow-up.

Discussion

The causal link between AVB and anorexia is discussed. In this case, patient’s eating disorder was related to her AV conduction abnormality. The main reason of this case report is to emphasize, that in children with unexplained anorexia and underweighting cardiogenic origin must be excluded.