Rare Presentation of Wide QRS Tachycardia in a Patient in Their 40s.

This article describes the case of a 40-year-old individual who presented with fulminant myocarditis. Initial ECG displayed sinus tachycardia with a heart rate of 117 bpm, QS complexes in leads V1-V3, ST-segment depression in leads II, III, aVF, V5-V6, and ST-segment elevation >0.2 mV in leads V1 through V3. The initial clinical assessment suggested an acute anteroseptal myocardial infarction. However, subsequent diagnostic evaluation through coronary angiography disclosed that the coronary arteries were normal. Therefore, clinicians should carefully consider the differential diagnosis between these conditions, as their management strategies differ markedly. Two hours after admission, the patient unexpectedly developed syncope. The ECG findings were consistent with the typical characteristics of bidirectional ventricular tachycardia. Our report described the appearance and morphology as well as mechanism of bidirectional ventricular tachycardia in detail. Additionally, we delineate differential diagnoses for disease that can cause bidirectional ventricular tachycardia, such as aconite poisoning, digoxin overdose, immune checkpoint inhibitor (ICI), myocardial ischemia, and hereditary channelopathies, such as catecholaminergic polymorphic ventricular tachycardia (CPVT) and Andersen-Tawil syndrome. Therefore, clinicians should recognize this ECG finding immediately and initiate appropriate treatment promptly as these measures may be vital in saving the patient's life.

Risk factors for tachycardia-induced cardiomyopathy due to atrial fibrillation.

BACKGROUND: Tachycardia-induced cardiomyopathy (TIC) is a reversible cardiomyopathy with ventricular dysfunction caused by tachyarrhythmias. Notably, atrial fibrillation (AF) is the most common causal arrhythmia leading to TIC. However, the risk factors for the development of TIC due to AF remain unclear. This study aimed to identify the associated factors of TIC due to AF. METHODS: Persistent AF patients with heart rate (HR) ≥100 beats per minute who underwent initial catheter ablation were enrolled in this study. TIC was diagnosed as left ventricular ejection fraction (LVEF) < 50% during AF rhythm, which was recovered after the restoration of sinus rhythm. Non-TIC was defined as LVEF ≥ 50% despite AF rhythm. The patient backgrounds were compared between the TIC group and the non-TIC group to reveal the contributing factors of TIC. RESULTS: The TIC group comprised 57 patients, while the non-TIC group consisted of 101 patients. The TIC group was younger than the non-TIC group (median 64 vs. 70, p = 0.006). Male sex was more frequent in the TIC group than the non-TIC group (82.5% vs. 58.4%, p = 0.003). HR was higher in the TIC group than in the non-TIC group (median 130 bpm vs. 111 bpm, p < 0.001). The number of smokers was significantly higher in the TIC group than in the non-TIC group (p < 0.001). Multivariable analysis demonstrated that higher HR (odds ratio [OR]: 1.74; 95% confidence interval [CI]: 1.37-2.21; p < 0.001) and current smokers (OR: 5.27; 95% CI: 1.60-17.4; p = 0.006) were the independent factors leading to TIC. CONCLUSION: Higher HR and current smokers were independent risk factors for the development of TIC due to AF.

A Small Wave Missed in Wide Complex Tachycardia.

This case report describes a patient in their 60s with intermittent palpitation, weakness, and irregular cardiac rhythm.

Comparison between catheter ablation versus permanent pacemaker implantation as an initial treatment for tachycardia-bradycardia syndrome patients: a prospective, randomized trial.

BACKGROUND: Clinical outcomes after catheter ablation (CA) or pacemaker (PM) implantation for the tachycardia-bradycardia syndrome (TBS) has not been evaluated adequately. We tried to compare the efficacy and safety outcomes of CA and PM implantation as an initial treatment option for TBS in paroxysmal atrial fibrillation (AF) patients. METHODS: Sixty-eight patients with paroxysmal AF and TBS (mean 63.7 years, 63.2% male) were randomized, and received CA (n = 35) or PM (n = 33) as initial treatments. The primary outcomes were unexpected emergency room visits or hospitalizations attributed to cardiovascular causes. RESULTS: In the intention-to-treatment analysis, the rates of primary outcomes were not significantly different between the two groups at the 2-year follow-up (19.8% vs. 25.9%; hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.25-2.20, P = 0.584), irrespective of whether the results were adjusted for age (HR 1.12, 95% CI 0.34-3.64, P = 0.852). The 2-year rate of recurrent AF was significantly lower in the CA group compared to the PM group (33.9% vs. 56.8%, P = 0.038). Four patients (11.4%) in the CA group finally received PMs after CA owing to recurrent syncope episodes. The rate of major or minor procedure related complications was not significantly different between the two groups. CONCLUSION: CA had a similar efficacy and safety profile with that of PM and a higher sinus rhythm maintenance rate. CA could be considered as a preferable initial treatment option over PM implantation in patients with paroxysmal AF and TBS. TRIAL REGISTRATION: KCT0000155.

The predictive value of heart rate in determining clinical course after a bupropion overdose.

INTRODUCTION: Bupropion is a popular antidepressant due to its favorable side effect profile and indications for smoking cessation and weight loss. Due to the possibility of delayed onset seizure and other adverse outcomes after bupropion overdose, patients are often observed for periods of 12-24 hours following suspected ingestion. Tachycardia is a clinical predictor that holds promise in differentiating cases at risk for seizures from low-risk cases that do not require prolonged observation. This study assessed whether heart rate within the first eight hours of presentation can identify cases that do not require extended observation. METHODS: This is a retrospective cohort study of all supra-therapeutic bupropion cases from two hospital systems between 2010 and 2022. RESULTS: Data from 216 charts were included. Seizures, hypotension, and dysrhythmias occurred in 19 percent (n = 41), 1.4 percent (n = 3), 0.9 percent (n = 2) respectively. One patient died. Delayed adverse effects were rare (n = 4); they occurred from 14 hours to 28 hours post-ingestion. Maximum heart rate in eight hours was associated with a risk of adverse outcomes. (odds ratio, 1.07; 95 percent confidence interval: 1.05 to 1.09; P < 0.001). An eight hour maximum heart rate threshold of 104 beats/minute had a negative predictive value of 100 percent (95 percent confidence interval: 96.7 percent to 100 percent) for the occurrence of delayed adverse effects. All patients with delayed effects had tachycardia within five hours of emergency department arrival. DISCUSSION: Delayed adverse outcomes of seizures, hypotension, dysrhythmia, and death were uncommon in this cohort. Heart rate during the first eight hours of observation performs reliably as a screening test to identify patients at low risk for delayed adverse outcomes. This study is limited by its retrospective nature, the inability to ascertain time of ingestion for most cases and the lack of confirmatory laboratory testing. CONCLUSION: This study supports the use of an eight hour observation period when there are no other clinical signs of toxicity to warrant admission and if no co-ingestion or administration of substances that mask tachycardia are present.

Ivabradine restores tonic cardiovascular autonomic control and reduces tachycardia, hypertension and left ventricular inflammation in post-weaning protein malnourished rats.

Malnutrition results in autonomic imbalance and heart hypertrophy. Overexpression of hyperpolarization-activated cyclic nucleotide-gated channels (HCN) in the left ventricles (LV) is linked to hypertrophied hearts and abnormal myocardium automaticity. Given that ivabradine (IVA) has emerging pleiotropic effects, in addition to the widely known bradycardic response, this study evaluated if IVA treatment could repair the autonomic control and cardiac damages in malnourished rats. AIM: Assess the impact of IVA on tonic cardiovascular autonomic control and its relationship with hemodynamics regulation, LV inflammation, and HCN gene expression in post-weaning protein malnutrition condition. MAIN METHODS: After weaning, male rats were divided into control (CG; 22 % protein) and malnourished (MG; 6 % protein) groups. At 35 days, groups were subdivided into CG-PBS, CG-IVA, MG-PBS and MG-IVA (PBS 1 ml/kg or IVA 1 mg/kg) received during 8 days. We performed jugular vein cannulation and electrode implant for drug delivery and ECG registration to assess tonic cardiovascular autonomic control; femoral cannulation for blood pressure (BP) and heart rate (HR) assessment; and LV collection to evaluate ventricular remodeling and HCN gene expression investigation. KEY FINDINGS: Malnutrition induced BP and HR increases, sympathetic system dominance, and LV remodeling without affecting HCN gene expression. IVA reversed the cardiovascular autonomic imbalance; prevented hypertension and tachycardia; and inhibited the LV inflammatory process and fiber thickening caused by malnutrition. SIGNIFICANCE: Our findings suggest that ivabradine protects against malnutrition-mediated cardiovascular damage. Moreover, our results propose these effects were not attributed to HCN expression changes, but rather to IVA pleiotropic effects on autonomic control and inflammation.

Partial Resistance to Thyroid Hormone-Induced Tachycardia and Cardiac Hypertrophy in Mice Lacking Thyroid Hormone Receptor ß.

Background: Thyroid hormones regulate cardiac functions mainly through direct actions in the heart and by binding to the thyroid hormone receptor (TR) isoforms α1 and ß. While the role of the most abundantly expressed isoform, TRα1, is widely studied and well characterized, the role of TRß in regulating heart functions is still poorly understood, primarily due to the accompanying elevation of circulating thyroid hormone in TRß knockout mice (TRß-KO). However, their hyperthyroidism is ameliorated at thermoneutrality, which allows studying the role of TRß without this confounding factor. Methods: Here, we noninvasively monitored heart rate in TRß-KO mice over several days using radiotelemetry at different housing temperatures (22°C and 30°C) and upon 3,3',5-triiodothyronine (T3) administration in comparison to wild-type animals. Results: TRß-KO mice displayed normal average heart rate at both 22°C and 30°C with only minor changes in heart rate frequency distribution, which was confirmed by independent electrocardiogram recordings in freely-moving conscious mice. Parasympathetic nerve activity was, however, impaired in TRß-KO mice at 22°C, and only partly rescued at 30°C. As expected, oral treatment with pharmacological doses of T3 at 30°C led to tachycardia in wild-types, accompanied by broader heart rate frequency distribution and increased heart weight. The TRß-KO mice, in contrast, showed blunted tachycardia, as well as resistance to changes in heart rate frequency distribution and heart weight. At the molecular level, these observations were paralleled by a blunted cardiac mRNA induction of several important genes, including the pacemaker channels Hcn2 and Hcn4, as well as Kcna7. Conclusions: The phenotyping of TRß-KO mice conducted at thermoneutrality allows novel insights on the role of TRß in cardiac functions in the absence of the usual confounding hyperthyroidism. Even though TRß is expressed at lower levels than TRα1 in the heart, our findings demonstrate an important role for this isoform in the cardiac response to thyroid hormones.

Clinical Characterization of Arrhythmia-Induced Cardiomyopathy in Patients With Tachyarrhythmia and Idiopathic Heart Failure.

BACKGROUND: Arrhythmia-induced cardiomyopathy (AIC) is a known entity, but prospective evidence for its characterization is limited. OBJECTIVES: This study aimed to: 1) determine the relative frequency of the pure form of AIC in the clinically relevant cohort of patients with newly diagnosed, otherwise unexplained left ventricular systolic dysfunction (LVSD) and tachyarrhythmia; 2) assess the time to recovery from LVSD; and 3) identify parameters for an early diagnosis of AIC. METHODS: Patients were prospectively included, underwent effective rhythm restoration, and were followed-up at 2, 4, and 6 months to evaluate clinical characteristics, biomarkers, and cardiac imaging including cardiac magnetic resonance imaging. Patients with recurred arrhythmia were excluded from analysis. RESULTS: 41 of 50 patients were diagnosed with AIC 6 months after rhythm restoration. Left ventricular (LV) ejection fraction increased 2 months after rhythm restoration from 35.4% ± 8.2% to 52.7% ± 8.0% in AIC patients vs 37.0% ± 9.5% to 43.3% ± 7.0% in non-AIC patients. From month 2 to 6, LV ejection fraction continued to increase in AIC patients (57.2% ± 6.1%; P < 0.001) but remained stable in non-AIC patients (44.0% ± 7.8%; P = 0.628). Multivariable logistic regression analysis revealed that lower LV end-diastolic diameter at baseline could be used for early diagnosis of AIC, whereas biomarkers and other morphological or functional parameters, including late LV gadolinium enhancement, did not show suitability for early diagnosis. CONCLUSIONS: We observed a high prevalence of AIC in patients with otherwise unexplained LVSD and concomitant tachyarrhythmia, suggesting that this condition may be underdiagnosed in clinical practice. Most patients recovered fast, within months, from LVSD. A low initial LV end-diastolic diameter may constitute an early marker for diagnosis of AIC.

Predicting factors for omitting beta-blockers in patients with tachycardia-induced cardiomyopathy after successful catheter ablation for atrial fibrillation.

Tachycardia induces a reduction in the left ventricular ejection fraction (LVEF), which is defined as tachycardia-induced cardiomyopathy (TIC). Conversion to and maintenance of sinus rhythm by catheter ablation can improve LVEF in patients with TIC due to atrial fibrillation (AF). Beta-blockers are mandatory for the treatment of heart failure with reduced LVEF(HFrEF), but the necessity of beta-blockers in TIC patients even after catheter ablation remains unclear. We examined the effect of beta-blockers on cardiac function in TIC patients after catheter ablation. We retrospectively analyzed 124 patients with a history of heart failure and an LVEF of ≤ 50% who underwent catheter ablation for AF. TIC was defined as a ≥ 10% improvement in the baseline LVEF and an improvement to an LVEF of ≥ 50% at 6 months after ablation. Patients with other cardiomyopathy diagnosed before the ablation were excluded. LVEF was significantly increased with the reductions of the left ventricular and left atrial volumes at the 6-month follow-up in all 80 patients with TIC. No beta-blockers were prescribed during the post-ablation follow-up in 21 patients with TIC. The absolute values of and changes in the echocardiographic parameters between before and after ablation were not significantly different between patients with and without beta-blockers after the ablation. A simple score using the history of hospitalization for heart failure and use of beta-blockers or diuretics prior to ablation was useful in identifying TIC patients who did not need prescription of beta-blockers after catheter ablation. LVEF similarly improved in both patients with and without prescription of beta-blockers after the ablation. Beta-blockers may not need to be prescribed after successful catheter ablation for AF in LVEF of ≤ 50% patients without other cause of cardiomyopathy diagnosed before the ablation, a history of hospitalization for heart failure and prescription of beta-blockers and diuretics before the ablation.

Adeno-associated virus-mediated gene therapy for cardiac tachyarrhythmia: A systematic review and meta-analysis.

Cardiac tachyarrhythmia presents a significant health care challenge, causing notable morbidity and mortality. Conventional treatments have limitations and potential risks, resulting in an elevated disease burden. Adeno-associated virus (AAV)-mediated gene therapy holds promise as a potential future treatment option. Therefore, we aimed to provide a measured overview of the latest developments in this rapidly growing field. PubMed and Embase databases were searched up to January 2024. Studies that employed AAV as a vector for delivery of therapeutic agents to treat cardiac tachyarrhythmia were included. Of the 26 studies included, 20 published in the last 5 years. There were 22 novel molecular targets identified. More than 80% of the included studies employed small-animal models or used AAV9. In atrial fibrillation preclinical studies, AAV-mediated gene therapy reduced atrial fibrillation inducibility by 81% (odds ratio, 0.19 [0.08-0.45]; P < .01). Similarly, for acquired and inherited ventricular arrhythmia, animal models receiving gene therapy had less inducible ventricular arrhythmia (odds ratio, 0.06 [0.03-0.11]; P < .01). This review highlights the rapid progress of AAV-mediated gene therapy for cardiac tachyarrhythmia. Although these investigations are currently in the early stages of clinical application, they present promising prospects for gene therapy. (PROSPERO registry: CRD42023479448).

Alteraciones electrocardiográficas periictales en pacientes pediátricos con epilepsia. Un estudio prospectivo / Peri-ictal electrocardiographic alterations in paediatric epilepsy patients. A prospective study

INTRODUCCIÓN: Las crisis epilépticas pueden asociarse a alteraciones del ritmo cardíaco periictales e incluso a muerte súbita (SUDEP). Existen escasos estudios pediátricos al respecto. OBJETIVO: Determinar las alteraciones del ritmo cardíaco en pacientes pediátricos con epilepsia estudiados con videoelectroencefalograma (video-EEG). MÉTODOS: Estudio prospectivo, observacional, en pacientes menores de 18 años ingresados para video-EEG en el Hospital Clínico Red de Salud UC-Christus, Santiago, Chile. Se realizó una evaluación neurológica y cardiológica, electrocardiograma (ECG) y Holter ECG simultáneo al video-EEG. RESULTADOS: Se estudió a 25 pacientes, 12 con epilepsias refractarias, 23/25 focales y 20 en tratamiento con politerapia. Se registraron 768 horas de video-EEG, incluyendo 281 crisis epilépticas en 15 pacientes: 157 clínicas y 103 generalizadas. No hubo arritmias graves; sólo alteraciones inespecíficas o probablemente benignas, principalmente bloqueo incompleto de la rama derecha en 11 pacientes, más frecuente en las epilepsias refractarias (p < 0,036). La variación de la frecuencia cardíaca ocurrió principalmente en crisis > 30 segundos. Ningún paciente ha presentado SUDEP. CONCLUSIONES: Éste es el primer estudio prospectivo, con una nueva técnica, usando simultáneamente video-EEG y Holter ECG en pediatría. Pese al alto número de crisis y pacientes refractarios, no encontramos alteraciones graves del ritmo cardíaco, en concordancia con la evaluación clínica. El bloqueo de la rama derecha se considera un hallazgo cardiológico no patológico, pero tuvo una alta prevalencia en nuestra muestra, comparada con la población normal, especialmente en la epilepsia refractaria. Dado que la SUDEP es un evento grave en la epilepsia, es importante ahondar más en este tipo de estudios para evaluar medidas preventivas

INTRODUCTION: Epileptic seizures can be associated with peri-ictal heart rhythm disorders and even sudden death (SUDEP). Few paediatric studies have been conducted on the subject. AIM: To determine heart rhythm disorders in paediatric patients with epilepsy who were studied with video-electroencephalogram (video-EEG). METHODS: Prospective, observational study in patients under 18 years of age admitted for video-EEG at the Hospital Clínico Red de Salud UC-Christus, Santiago, Chile. A neurological and cardiological evaluation and electrocardiogram (ECG) were performed, in addition to a Holter ECG simultaneously with the video-EEG. RESULTS: Twenty-five patients were studied, 12 with refractory epilepsies, 23/25 focal and 20 on polytherapy. Altogether 768 hours of video-EEG were recorded, including 281 seizures in 15 patients: 157 clinical and 103 generalised. There were no serious arrhythmias, only non-specific or probably benign disorders, mainly incomplete right bundle branch block in 11 patients, which were more frequent in refractory epilepsies (p < 0.036). Heart rate variation occurred mainly in seizures >30 seconds. No patient presented SUDEP. CONCLUSIONS: This is the first prospective study, with a new technique, using video-EEG and Holter ECG simultaneously in paediatrics. Despite the high number of seizures and refractory patients, we found no serious heart rhythm disorders, consistent with the clinical evaluation. Right bundle branch block is considered a non-pathological cardiological finding, but was highly prevalent in our sample compared to the normal population, especially in refractory epilepsy. Given that this is a serious event in epilepsy, it is important to further investigate such studies to assess preventive measures

Diagnóstico diferencial de las taquicardias de complejo ancho: un desafío permanente / Wide QRS tachycardia: a diagnostic challenge

El diagnóstico electrocardiográfico correcto de la causa de una taquicardia de complejo QRS ancho (TCA) es fundamental, ya que tanto el manejo, como el pronóstico del paciente, es diferente según su etiología, y define el estudio que debemos realizar. Numerosos criterios y algoritmos han sido descritos para diferenciar el origen de estas taquicardias. Sin embargo, muchos de estos son complejos y difíciles de aplicar para el médico menos experimentado. Esto es particularmente importante en los servicios de emergencia, donde se necesita una definición rápida que permita un manejo agudo apropiado. En la presente revisión analizamos los diferentes mecanismos de las TCA y los principales criterios diagnósticos en el ECG, reforzando, especialmente, aquellos de aplicación rápida y de alto rendimiento diagnóstico.

The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis of the patient. The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis is different according to its etiology and defines the study that we should perform. Numerous criteria and algorithms have been described to differentiate the origin of these tachycardias. However, many of these are complex and difficult to apply to the less experienced doctor. This is particularly important in emergency rooms, where a rapid definition is needed to allow proper therapy. In this review we analyze the different mechanisms of WCT and the main EKG diagnostic criteria, emphasizing those which can be applied rapidly and have high diagnostic value.

Glutamate receptors of the A5 region modulate cardiovascular responses evoked from the dorsomedial hypothalamic nucleus and perifornical area

To assess the possible function of glutamate in the interaction between the dorsomedial hypothalamic nucleus-perifornical area (DMH-PeF) and the A5 pontine region (A5), cardiovascular and respiratory changes were studied in response to electrical stimulation of the DMH-PeF (1 ms pulses, 30-50 miA given at 100 Hz for 5 s) before and after the microinjection of kynurenic acid (non-specific glutamate receptor antagonist; 50 nl, 5 nmol), MK-801 (NMDA receptor antagonist; 50 nl, 50 nmol), CNQX (non-NMDA receptor antagonist; 50 nl, 50 nmol) or MCPG (metabotropic glutamate receptor antagonist; 50 nl, 5 nmol) within the A5 region. DMH-PeF electrical stimulation elicited a pressor (p < 0.001) and tachycardic response (p < 0.001) which was accompanied by an inspiratory facilitation characterised by an increase in respiratory rate (p < 0.001) due to a decrease in expiratory time (p < 0.01). Kynurenic acid within the A5 region decreased the tachycardia (p < 0.001) and the intensity of the blood pressure response (p < 0.001) to DMH-PeF stimulation. After the microinjection of MK-801 and CNQX into the A5 region, the magnitude of the tachycardia and the pressor response were decreased (p < 0.05 and p < 0.01; p < 0.001 and p < 0.05, respectively). After MCPG microinjection into the A5 region, a decrease in the tachycardia (p < 0.001) with no changes in the pressor response was observed during DMH-PeF stimulation. The respiratory response elicited by DMH-PeF stimulation was not changed after the microinjection of kynurenic acid, MK-801, CNQX or MCPG within the A5 region. These results suggest that A5 region glutamate receptors play a role in the cardiovascular response elicited from the DMH-PeF. The possible mechanisms involved in these interactions are discussed

Taquicardia de complejo ancho en paciente con fibrilación auricular permanente / Wide QRS tachycardia in a patient with persistent atrial fibrillation

Un hombre de 80 años con historia de diabetes mellitus e infarto antiguo del miocardio es ingresado con insuficiencia cardíaca y neumopatía aguda. Presentaba Fibrilación auricular y no recibía antiarrítmicos. Despues de administración de broncodilatadores desarrolló una taquicardia a complejo ancho. Se presentan los trazados electrocardiográficos y se discute el mecanismo de la arritmia.

An 80 year old man, with a history of diabetes mellitus and remote myocardial infarction is admitted with heart failure and pneumonia He was in atrial fibrillation and was not on anti arrhythmic drugs. After receiving broncodilators he developed a wide QRS tachycardia. ECG tracings are presented and the mechanism of this tachycardia is discussed.

Descarga inapropiada de desfibrilador en un dispositivo subcutáneo secundaria a contracciones musculares repetitivas / Inappropriate Defibrillator Shock in a Subcutaneous Device Secondary to Repetitive Muscle Contractions

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