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Ventricular tachycardia [keywords]
- The Janus Face of Adenosine: Antiarrhythmic and Proarrhythmic Actions. [JOURNAL ARTICLE]
- Curr Pharm Des 2014 Oct 28.
Adenosine is a ubiquitous, endogenous purine involved in a variety of physiological and pathophysiological regulatory mechanisms. Adenosine has been proposed as an endogenous antiarrhythmic substance to prevent hypoxia/ischemia-induced arrhythmias. Adenosine (and its precursor, ATP) has been used in the therapy of various cardiac arrhythmias over the past six decades. Its primary indication is treatment of paroxysmal supraventricular tachycardia, but it can be effective in other forms of supraventricular and ventricular arrhythmias, like sinus node reentry based tachycardia, triggered atrial tachycardia, atrioventricular nodal reentry tachycardia, or ventricular tachycardia based on a cAMP-mediated triggered activity. The main advantage is the rapid onset and the short half life (1-10 sec). Adenosine exerts its antiarrhythmic actions by activation of A1 adenosine receptors located in the sinoatrial and atrioventricular nodes, as well as in activated ventricular myocardium. However, adenosine can also elicit A2A, A2B and A3 adenosine receptor-mediated global side reactions (flushing, dyspnea, chest discomfort), but it may display also proarrhythmic actions mediated by primarily A1 adenosine receptors (e.g. bradyarrhythmia or atrial fibrillation). To avoid the non-specific global adverse reactions, A1 adenosine receptor-selective full agonists (tecadenoson, selodenoson, trabodenoson) have been developed, which agents are currently under clinical trial. During long-term administration with orthosteric agonists, adenosine receptors can be internalized and desensitized. To avoid desensitization, proarrhythmic actions, or global adverse reactions, partial A1 adenosine receptor agonists, like CVT-2759, were developed. In addition, the pharmacologically "silent" site- and event specific adenosinergic drugs, such as adenosine regulating agents and allosteric modulators, might provide attractive opportunity to increase the effectiveness of beneficial actions of adenosine and avoid the adverse reactions.
- Value of the Qrs-T Angle in Predicting the Induction of Ventricular Tachyarrhythmias in Patients with Chagas Disease. [JOURNAL ARTICLE]
- Arq Bras Cardiol 2014 Oct 28.:12.
Background: The QRS-T angle correlates with prognosis in patients with heart failure and coronary artery disease, reflected by an increase in mortality proportional to an increase in the difference between the axes of the QRS complex and T wave in the frontal plane. The value of this correlation in patients with Chagas heart disease is currently unknown. Objective: Determine the correlation of the QRS-T angle and the risk of induction of ventricular tachycardia / ventricular fibrillation (VT / VF) during electrophysiological study (EPS) in patients with Chagas disease. Methods: Case-control study at a tertiary center. Patients without induction of VT / VF on EPS were used as controls. The QRS-T angle was categorized as normal (0-105º), borderline (105-135º) or abnormal (135-180º). Differences between groups for continuous variables were analyzed with the t test or Mann-Whitney test, and for categorical variables with Fisher's exact test. P values < 0.05 were considered significant. Results: Of 116 patients undergoing EPS, 37.9% were excluded due to incomplete information / inactive records or due to the impossibility to correctly calculate the QRS-T angle (presence of left bundle branch block and atrial fibrillation). Of 72 patients included in the study, 31 induced VT / VF on EPS. Of these, the QRS-T angle was normal in 41.9%, borderline in 12.9% and abnormal in 45.2%. Among patients without induction of VT / VF on EPS, the QRS-T angle was normal in 63.4%, borderline in 14.6% and abnormal in 17.1% (p = 0.04). When compared with patients with normal QRS-T angle, those with abnormal angle had a fourfold higher risk of inducing ventricular tachycardia / ventricular fibrillation on EPS [odds ratio (OR) 4; confidence interval (CI) 1.298-12.325; p = 0.028]. After adjustment for other variables such as age, ejection fraction (EF) and QRS size, there was a trend for the abnormal QRS-T angle to identify patients with increased risk of inducing VT / VF during EPS (OR 3.95; CI 0.99-15.82; p = 0.052). The EF also emerged as a predictor of induction of VT / VF: for each point increase in EF, there was a 4% reduction in the rate of sustained ventricular arrhythmia on EPS. Conclusions: Changes in the QRS-T angle and decreases in EF were associated with an increased risk of induction of VT / VF on EPS.Fundamento: O ângulo QRS-T mostra correlação com prognóstico em pacientes com insuficiência cardíaca e doença coronariana, traduzido por um aumento na mortalidade proporcional ao aumento na diferença entre os eixos do complexo QRS e da onda T no plano frontal. Até hoje, nenhuma informação a este respeito foi obtida em pacientes com cardiopatia chagásica. Objetivo: Correlacionar o ângulo QRS-T com a indução de taquicardia ventricular / fibrilação ventricular (TV / FV) em chagásicos durante estudo eletrofisiológico (EEF). Métodos: Estudo caso-controle em centro terciário. Pacientes sem indução de TV / FV ao EEF foram utilizados como controles. O ângulo QRS-T foi categorizado como normal (0-105º), limítrofe (105-135º) e anormal (135-180º). As diferenças entre os grupos foram analisadas pelo teste t ou teste de Mann-Whitney para variáveis contínuas, e teste exato de Fisher ou qui-quadrado para variáveis categóricas. Valores de p < 0,05 foram considerados significativos. Resultados: De 116 pacientes submetidos ao EEF, 37,9% foram excluídos por estarem com dados incompletos / prontuários inativos ou pela impossibilidade de se calcular corretamente o ângulo QRS-T (presença de bloqueio de ramo esquerdo e fibrilação atrial). De 72 pacientes incluídos, 31 induziram TV / FV ao EEF. Destes, o ângulo QRS-T se encontrava normal em 41,9%, limítrofe em 12,9% e anormal em 45,2%. No grupo de pacientes sem indução de TV / FV, o ângulo QRS-T se encontrava normal em 63,4%, limítrofe em 14,6% e anormal em 17,1% (p = 0,04). Quando comparados aos pacientes com ângulo QRS-T normal, o risco de indução de TV / FV nos pacientes com ângulo anormal foi quatro vezes maior [odds ratio (OR) 4; intervalo de confiança (IC) 1,298-12,325; p = 0,028). Após ajuste para outras variáveis como idade, fração de ejeção (FE) e tamanho do QRS, houve tendência do ângulo QRS-T anormal em identificar pacientes com maior risco de indução de TV / FV (OR 3,95; IC 0,99-15,82; p = 0,052). A FE também se evidenciou como preditora de indução de TV / FV: um ponto de aumento na FE reduziu em 4% a taxa de indução de arritmia ventricular sustentada ao EEF. Conclusões: Alterações no ângulo QRS-T e redução na FE estiveram associadas a um aumento no risco de indução de TV / FV ao EEF.
- Differences in quantitative assessment of myocardial scar and gray zone by LGE-CMR imaging using established gray zone protocols. [JOURNAL ARTICLE]
- Int J Cardiovasc Imaging 2014 Oct 29.
Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging is the gold standard for myocardial scar evaluation. Heterogeneous areas of scar ('gray zone'), may serve as arrhythmogenic substrate. Various gray zone protocols have been correlated to clinical outcomes and ventricular tachycardia channels. This study assessed the quantitative differences in gray zone and scar core sizes as defined by previously validated signal intensity (SI) threshold algorithms. High quality LGE-CMR images performed in 41 cardiomyopathy patients [ischemic (33) or non-ischemic (8)] were analyzed using previously validated SI threshold methods [Full Width at Half Maximum (FWHM), n-standard deviation (NSD) and modified-FWHM]. Myocardial scar was defined as scar core and gray zone using SI thresholds based on these methods. Scar core, gray zone and total scar sizes were then computed and compared among these models. The median gray zone mass was 2-3 times larger with FWHM (15 g, IQR: 8-26 g) compared to NSD or modified-FWHM (5 g, IQR: 3-9 g; and 8 g. IQR: 6-12 g respectively, p < 0.001). Conversely, infarct core mass was 2.3 times larger with NSD (30 g, IQR: 17-53 g) versus FWHM and modified-FWHM (13 g, IQR: 7-23 g, p < 0.001). The gray zone extent (percentage of total scar that was gray zone) also varied significantly among the three methods, 51 % (IQR: 42-61 %), 17 % (IQR: 11-21 %) versus 38 % (IQR: 33-43 %) for FWHM, NSD and modified-FWHM respectively (p < 0.001). Considerable variability exists among the current methods for MRI defined gray zone and scar core. Infarct core and total myocardial scar mass also differ using these methods. Further evaluation of the most accurate quantification method is needed.
- Surgical ventricular reconstruction and subendocardial resection for the treatment of refractory ventricular tachycardia. [Journal Article]
- Ann R Coll Surg Engl 2014 Nov; 96(8):26-7.
We describe a case of 64-year-old female patient with ventricular tachycardia intractable to medical treatment and acute heart failure following myocardial infarction. Emergency surgical ventricular reconstruction and subendocardial resection was undertaken. We discuss the option of surgical intervention in this difficult and unusual clinical scenario.
- Electrical storm in systemic sclerosis: Inside the electroanatomic substrate. [Journal Article]
- World J Cardiol 2014 Oct 26; 6(10):1127-30.
We report the case of a 63-year-old woman affected by a severe form of systemic scleroderma with pulmonary involvement (interstitial fibrosis diagnosed by biopsy and moderate pulmonary hypertension) and cardiac involvement (paroxysmal atrial fibrillation, right atrial flutter treated by catheter ablation, ventricular tachyarrhythmias, previous dual chamber implantable cardioverter defibrillator implant). Because of recurrent electrical storms refractory to iv antiarrhythmic drugs the patient was referred to our institution to undergo catheter ablation. During electrophysiological procedure a 3D shell of cardiac anatomy was created with intracardiac echocardiography pointing out a significant right ventricular dilatation with a complex aneurysmal lesion characterized by thin walls and irregular multiple trabeculae. A substrate-guided strategy of catheter ablation was accomplished leading to a complete electrical isolation of the aneurism and to the abolishment of all abnormal electrical activities. The use of advanced strategies of imaging together with electroanatomical mapping added important information to the complex arrhythmogenic substrate and improved efficacy and safety.
- Clinical impact of a novel three-dimensional electrocardiographic imaging for non-invasive mapping of ventricular arrhythmias-a prospective randomized trial. [JOURNAL ARTICLE]
- Europace 2014 Oct 27.
ECVUE™ technology, a novel, three-dimensional, non-invasive mapping system, offers a unique arrhythmia characterization and localization. We sought to evaluate the clinical impact of this system in routine clinical mapping and ablation of ventricular arrhythmias (VAs).Patients with monomorphic premature ventricular contractions with or without monomorphic ventricular tachycardia were enrolled prospectively and randomized into two groups: ventricular ectopy localization using either 12-lead electrocardiogram (ECG) algorithms or with ECVUE™, followed by conventional guided ablation. Forty-two patients were enrolled in the study. The ECVUE™ system accurately identified both the chamber and sub-localized the VA origin in 20 of 21 (95.2%) patients. In contrast, using 12-lead ECG algorithms, the chamber was accurately diagnosed in 16 of 21 (76.2%) patients, while the arrhythmia origin in only 8 of 21 (38.1%), (P = 0.001 vs. ECVUE™). Acute success in ablation was achieved in all patients. Regarding the number of radiofrequency-energy applications (in total 2 vs. 4, P = 0.005) in the ECVUE™ arm, ablation was more precise than the ECG group which used standard of care activation and pace mapping-guided ablation. Three months success in ablation was 95.2% for the ECVUE™ and 100% for the ECG group (P = ns). Time to ablation was 35.3 min in the conventional arm and 24.4 min in ECVUE Group, (P = 0.035). The X-ray radiation exposure was 3.21 vs. 0.39 mSv, P = 0.001 for the ECVUE™ group and ECG group.ECVUE™ technology offers a clinically useful tool to map VAs with high accuracy and more targeted ablations superior to the body surface ECG but had significantly higher radiation exposure due to computed tomography scan.
- Incidence and timing of serious arrhythmias after early revascularization in non ST-elevation myocardial infarction. [JOURNAL ARTICLE]
- Eur Heart J Acute Cardiovasc Care 2014 Oct 27.
In contrast to ST-elevation myocardial infarction (STEMI), in non-STEMI (NSTEMI) patients the need for continuous rhythm monitoring in a coronary care unit, respective incidence and timing of serious arrhythmias are poorly defined.We used a derivation-validation design and data from two independent prospective cohorts of consecutive haemodynamically stable NSTEMI patients to evaluate the incidence and timing of serious arrhythmias after successful early percutaneous revascularization. Serious arrhythmia was prospectively defined as any arrhythmia that requires immediate medical attention including persistent ventricular tachycardia (>30 s), ventricular fibrillation, asystole, and high degree atrioventricular (AV)-block requiring pacemaker insertion during hospitalization.In the derivation cohort, among 228 NSTEMI patients who underwent successful early percutaneous revascularization, one patient (0.4%, 95% confidence interval 0.02-2.8%) had a serious arrhythmia which occurred 21 h after revascularization. In the validation cohort, among 293 NSTEMI patients who underwent successful early percutaneous revascularization, no patient (0%, 95% confidence interval 0-1.6%) had a serious arrhythmia after revascularization.The incidence of serious arrhythmias in NSTEMI patients after successful early revascularization seems to be very low.
- Evaluation Rhythm Problems in Unexplained Syncope Etiology with Implantable Loop Recorder. [JOURNAL ARTICLE]
- Pediatr Int 2014 Oct 28.
Syncope is a frequent complaint in children and adolescents and may be an significant sign of serious pathologies. Although the patient history, family history, and a physical examination are sufficient to reach a diagnosis in most cases of syncope, the cause of syncope still cannot be determined after initial investigations in from one-third to half of all patients. In this study, our aim is to evaluate the diagnostic yield of the implantable loop recorder (ILR) in children with unexplained syncope.A retrospective review of clinical data, indications, findings, and a final management strategy in patients who underwent ILR implantation.A total of 12 patients with a mean age of 9.4 ± 4.5 years underwent ILR (Reveal Plus, Medtronic, USA) implantation. ILR implantation indication was "syncope" in all of the patients. The family history, routine cardiac assessments, including resting 12 lead electrocardiograms, a transthoracic echocardiography, 24 hour Holter recordings, and event recorder findings, were normal with the exception of one patient with operated because of tetralogy of Fallot. After an average of 20 months (1-36 months), 6 patients developed symptoms. The ILR memory showed torsades de pointes - ventricular fibrillation (3), CPVT (1), asystole and ventricular tachycardia (1), and normal sinus rhythm (1). Six patients are still in follow-up with no symptoms after an average of 25.2 months.Implantable loop recorders play an important role in the diagnosis of life-threatening arrhythmias in which syncope is otherwise unexplained. ILR implantation should be remembered in children whose symptoms are strongly correlated with rhythm disturbances.
- [Electrocardiologic opportunities for the treatment of recurrent ventricular tachycardia on the example of a patient with arrhythmogenic right ventricular dysplasia]. [English Abstract, Journal Article]
- Przegl Lek 2014; 71(6):355-8.
Arrhythmogenic right ventricular dysplasia is a genetic disease, in which pathologic fibrofatty tissue occurs mainly in the right ventricle of the heart. Changes in heart muscle predispose to arrhythmias such as ventricular tachycardia or ventricular fibrillation, so these patients are candidates for implantation of implantable cardioverter-defibrillator. Furthermore, depending on the indication, RF-ablation is performed, which, due to changes in morphology of the heart muscle, are often difficult and of uncertain efficacy. In this paper we present a case of a patient with implanted cardioverter-defibrillator for primary prevention of sudden cardiac death. Initially, the patient experienced only complications related to the possession of the device, but due to the significant progression of the disease and symptoms, the device turned out to be necessary. In addition, the patient underwent complex electrophysiology procedures to control recurrent episodes of ventricular tachycardia. Treatment of cardiac arrhythmias in arrhythmogenic right ventricular dysplasia is problematic both because of the inability to predict the course of disease in asymptomatic patients, as well as due to the difficulty of carrying out effective ablation of arrhythmia foci in morphologically altered myocardium.
- Lack of UCP3 does not affect skeletal muscle mitochondrial function under lipid-challenged conditions, but leads to sudden cardiac death. [JOURNAL ARTICLE]
- Basic Res Cardiol 2014 Nov; 109(6):447.
UCP3's exact physiological function in lipid handling in skeletal and cardiac muscle remains unknown. Interestingly, etomoxir, a fat oxidation inhibitor and strong inducer of UCP3, is proposed for treating both diabetes and heart failure. We hypothesize that the upregulation of UCP3 upon etomoxir serves to protect mitochondria against lipotoxicity. To evaluate UCP3's role in skeletal muscle (skm) and heart under lipid-challenged conditions, the effect of UCP3 ablation was examined in a state of dysbalance between fat availability and oxidative capacity. Wild type (WT) and UCP3(-/-) mice were subjected to high-fat feeding for 14 days. From day 6 onwards, they were given either saline or etomoxir. Etomoxir treatment induced an increase in markers of lipotoxicity in skm compared to saline. This increase upon etomoxir was similar for both, WT and UCP3(-/-) mice, suggesting that UCP3 does not play a role in protection against lipotoxicity. Interestingly, we observed 25 % mortality in UCP3(-/-)s upon etomoxir administration vs. 11 % in WTs. This increased mortality in UCP3(-/-) compared to WT mice could not be explained by differences in cardiac lipotoxicity, apoptosis, fibrosis (histology, immunohistochemistry), oxidative capacity (respirometry) or function (echocardiography). Electrophysiology demonstrated, however, prolonged QRS and QTc intervals and greater susceptibility to ventricular tachycardia upon programmed electrical stimulation in etomoxir-treated UCP3(-/-)s versus WTs. Isoproterenol administration after pacing resulted in 75 % mortality in UCP3(-/-)s vs. 14 % in WTs. Our results argue against a protective role for UCP3 on skm metabolism under lipid overload, but suggest UCP3 to be crucial in prevention of arrhythmias upon lipid-challenged conditions.