Ventricular arrhythmias.

Sudden cardiac death claims thousands of Canadians annually. Ventricular tachycardia and fibrillation account for up to 85% of these deaths. Identifying the patients at risk remains a major challenge. Those who have recurrent ventricular tachycardia or have been resuscitated from ventricular fibrillation are generally considered to be at highest risk. Although ventricular premature beats in the absence of previous ventricular tachycardia or fibrillation are not helpful in identifying such patients in most cases, they can indicate increased risk for sudden cardiac death in the presence of a structural cardiac abnormality, particularly recent myocardial infarction; however, the need for treatment in such cases is speculative and is being investigated. Treatment is mandatory for survivors of an episode of ventricular fibrillation and those with recurrent sustained ventricular tachycardia or torsade de pointes ventricular tachycardia. The approach to management is either invasive or noninvasive. Selection of an antiarrhythmic agent is facilitated by knowledge of some basic electrophysiologic features of the heart and of the classification of antiarrhythmic drugs. However, drug therapy has to be individualized on the basis of efficacy, left ventricular function and adverse effects or potential adverse effects of the drug. Amiodarone therapy or nonpharmacologic therapy should be considered if a suitable antiarrhythmic agent cannot be found.     

室性早搏患者射频消融术预后与起源部位的相关性

目的:探讨室性早搏(PVCs)患者射频消融术(RFCA)预后与起源部位的相关性。方法:回顾性分析2016年12月～2017年12月第二军医大学第一附属医院长海医院心血管内科收治并接受RFCA治疗的PVCs患者的临床资料,根据起源部位分为右心室组(n=58),左心室组(n=24)。记录两组RFCA手术时间、X线曝光时间及手术成功率等指标,术后随访6个月,比较两组术后心功能指标的改善情况,记录24h PVCs总数及复发情况。结果:与左心室组比较,右心室组手术时间、X线曝光时间明显延长,手术成功率明显下降(P0.05)。术后3个月,右心室组LVESD、LVEDD均明显减小,LVEF明显升高(P0.05);术后6个月,两组24h PVCs数均较术前显著降低,且右心室组下降幅度更为显著(P0.05)。术后6个月,两组各心功能指标均较术前明显改善,右心室组较术后3个月进一步改善,且明显优于左心室组(P0.05)。结论:射频消融术治疗PVCs的预后与起源部位存在一定相关性,右心室起源相对左心室起源的PVCs手术成功率更高,更有利于抑制心室重构、改善心功能。     

心血管危重症继发交感风暴37例临床分析

目的:探讨心血管危重症继发交感风暴的病因分布特点和治疗方法。方法:回顾性分析我院2001年-2011年37例心血管危重症继发交感风暴临床资料。结果:37例心血管危重症继发交感风暴患者,其中男性22例,女性15例,年龄55-82岁,平均68.25岁。病因分布为:心肌梗死29例,心衰3例,扩张性心肌病2例,电解质紊乱2例,Brugada综合征1例。治疗方法包括β受体阻滞剂、胺碘酮、利多卡因、电除颤等。其中,17例因反复发作室颤,经抗心律失常药物和电除颤治疗无效死亡,余20例病情得到控制。结论:心血管危重症继发交感风暴临床病因多样,病情凶险,应用β受体阻滞剂及抗心律失常药物,同时积极针对病因及诱因治疗,可以改善临床症状和预后。     

Radiofrequency Catheter Ablation of Idiopathic Right Ventricular Outflow Tract Arrhythmias

Idiopathic ventricular arrhythmias (VA) consist of various subtypes of VA that occur in the absence of clinically apparent structural heart disease. Affected patients account for approximately 10% of all patients referred for evaluation of ventricular tachycardia (VT). Arrhythmias arising from the outflow tract (OT) are the most common subtype of idiopathic VA and more than 70–80% of idiopathic VTs or premature ventricular contractions (PVCs) originate from the right ventricular (RV) OT. Idiopathic OT arrhythmias are thought to be caused by adenosine-sensitive, cyclic adenosine monophosphate (cAMP) mediated triggered activity and, in general, manifest at a relatively early age. Usually they present as salvos of paroxysmal ventricular ectopic beats and are rarely life-threatening. When highly symptomatic and refractory to antiarrhythmic therapy or causative for ventricular dysfunction, ablation is a recommended treatment with a high success rate and a low risk of complications.     

n-3 Fatty acids, cardiac arrhythmia and fatal coronary heart disease

n-3 Polyunsaturated fatty acids (n-3 PUFA) are suggested to prevent cardiac death via inhibition of cardiac arrhythmia. In this review we discuss the results of human studies on intake of n-3 PUFAs and heart disease and, more specifically, on cardiac arrhythmia. Observational studies indicate that intake of fish is associated with a lower incidence of fatal coronary heart disease in several populations. These studies are fairly consistent, but people that have a high intake of fatty fish might have a healthier lifestyle in general, and such confounding is difficult to remove completely with statistical adjustments and corrections. Evidence from trials is less clear. In two open label trials in patients with a previous myocardial infarction intake of fish or fish oil prevented fatal coronary heart disease. In contrast, a trial in patients with angina suggested a higher risk of sudden cardiac death in patients taking fish oil. Furthermore, results of trials in patients with an implantable cardioverter defibrillator (ICD) that investigated effects of fish oil on arrhythmia in patients already suffering from ventricular tachycardia are not consistent. Also, studies on relationships between intake of n-3 PUFA from fish and less life-threatening forms of arrhythmia, such as atrial fibrillation and premature ventricular complexes (PVCs) are equivocal. Thus, after 35 years of research the question whether fish prevents heart disease remains unanswered, and an anti-arrhythmic effect of fish oil remains unproven although the idea is still viable and is being actively tested in further trials.     

Pharmacological treatment of short-coupled idiopathic ventricular fibrillation: A review

Short-coupled idiopathic ventricular fibrillation (IVF) is a subtype of IVF in which episodes of polymorphic ventricular tachycardia or ventricular fibrillation are initiated by short-coupled premature ventricular contractions (PVCs). Our understanding of the pathophysiology is evolving, with evidence suggesting that these malignant PVCs originate from the Purkinje system. In most cases, the genetic underpinning has not been identified. Whereas the implantation of an implantable cardioverter-defibrillator is uncontroversial, the choice of pharmacological treatment is the subject of discussion. In this review, we summarize the available knowledge on pharmacological therapy in short-coupled IVF and provide our recommendations for management of patients with this syndrome.     

Ablation of Premature Ventricular Complexes Triggering Ventricular Fibrillation in a Patient with Long QT Syndrome

We describe the case of a patient with long QT syndrome and recurrent ventricular fibrillation, triggered by premature ventricular complexes (PVCs) with a left bundle branch block pattern and inferior axis of the QRS. Activation mapping demonstrated the origin of the PVCs to be in the right ventricular outflow tract. Ventricular fibrillation (VF) was successfully treated by catheter ablation of the triggering PVCs and there has been no recurrence of VF during a follow-up period of 14 months.     

The Different Substrate Characteristics of Arrhythmogenic Triggers in Idiopathic Right Ventricular Outflow Tract Tachycardia and Arrhythmogenic Right Ventricular Dysplasia: New Insight from Noncontact Mapping

BackgroundThe aim of this study was to investigate the different substrate characteristics of repetitive premature ventricular complexed (PVC) trigger sites by the non-contact mapping (NCM).MethodsThirty-five consecutive patients, including 14 with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) and 21 with idiopathic right ventricular outflow tract tachycardia (RVOT VT), were enrolled for electrophysiological study and catheter ablation guided by the NCM. Substrate and electrogram (Eg) characteristics of the earliest activation (EA) and breakout (BO) sites of PVCs were investigated, and these were confirmed by successful PVC elimination.ResultsOverall 35 dominant focal PVCs were identified. PVCs arose from the focal origins with preferential conduction, breakout, and spread to the whole right ventricle. The conduction time and distance from EA to BO site were both longer in the ARVC than the RVOT group. The conduction velocity was similar between the 2 groups. The negative deflection of local unipolar Eg at the EA site (EA slope_3,5,10ms values) was steeper in the RVOT, compared to ARVC patients. The PVCs of ARVC occurred in the diseased substrate in the ARVC patients. More radiofrequency applications were required to eliminate the triggers in ARVC patients.Conclusions/InterpretationThe substrate characteristics of PVC trigger may help to differentiate between idiopathic RVOT VT and ARVC. The slowing and slurred QS unipolar electrograms and longer distance from EA to BO in RVOT endocardium suggest that the triggers of ARVC may originate from mid- or sub-epicardial myocardium. More extensive ablation to the trigger site was required in order to create deeper lesions for a successful outcome.     

Prognostic significance of accelerated ventricular response during radiofrequency ablation of premature ventricular complexes

BackgroundAccelerated ventricular response is frequently observed during radiofrequency ablation (RFA) of premature ventricular complexes (PVCs). We hypothesized that acceleration indicates an appropriate site and adequate injury to the arrhythmogenic tissue, and sought to investigate its value in predicting the outcome.MethodsWe retrospectively analyzed RFA procedures performed for PVCs in our institution from 2011 to 2019.ResultsFifty-eight patients (29 male; age 42.7 ± 15.6 years) underwent 62 RFA procedures. The most common site was the right ventricular outflow tract (67.7%). Acute success was seen in 88.7%. Accelerated ventricular response was observed in 60.0% of the successful procedures. After a median follow-up of 14.0 months (IQR: 6.0–26.6 months), 16 patients had a recurrence. Recurrence was significantly lower in the group with acceleration than in the group without acceleration (12.5% vs. 57.1%; log-rank P < 0.001). The 1-year recurrence rate was 6.5% in the acceleration group and 41.6% in the group without acceleration. On multivariable analysis the adjusted hazard ratio was 0.17 (95% CI, 0.04–0.64; Cox regression P = 0.009). The sensitivity, specificity, positive predictive, and negative predictive values of accelerated response to predict long-term success were 75.7%, 75.0%, 87.5%, and 57.2%, respectively.ConclusionsThe recurrence after PVC ablation is significantly lower when an accelerated response was observed at the successful location during RFA. This can be an additional useful marker of long-term success.     

Anaphylactic reaction associated with Ranitidine in a patient with acute pancreatitis: a case report

Sustained chronic tachyarrhythmias often cause a deterioration of cardiac function known as tachycardia-induced cardiomyopathy or tachycardiomyopathy. The incidence of tachycardia-induced cardiomyopathy is unknown, but in selected studies of patients with atrial fibrillation, approximately 25% to 50% of those with left ventricular dysfunction had some degree of tachycardia-induced cardiomyopathy. It is an important clinical entity due to the high incidence and potential reversibility of the disease process. This case describes a cardiomyopathy induced by excess caffeine consumption. Six months following withdrawal of caffeine from the subject's diet, full resolution of symptoms occurred.     

Ventricular tachycardia in repaired double chambered right ventricle - identification of the substrate and successful ablation

A 35 year old female presented with recurrent ventricular tachycardia 5 years after she had undergone surgical repair of double chambered right ventricle. Electroanatomical mapping showed a localised scar in the apex with double potentials and good pace map. Ablation here resulted in non-inducibility of ventricular tachycardia. We hypothesise that the scarring in the apex is the result of sustained pressure overload and becomes arrhythmogenic similar to the apical scar in patients with mid-ventricular hypertrophic cardiomyopathy.     

Verapamil Sensitive Ventricular Tachycardia Associated With A Cardiac Hemangioma In The Right Ventricular Outflow Tract

Primary tumors of the heart are rare, but they are often associated with refractory arrhythmias. Vascular tumors of the heart comprise a small minority of primary cardiac tumors. In patients with structurally normal hearts, ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) can be sensitive to adenosine, vagal maneuvers, and calcium channel blockers. In this report, we describe a case of ventricular tachycardia originating from within a hemangioma in the RVOT that was ultimately controlled with verapamil.     

Ventricular tachycardia ablation in children

IntroductionThe ablation of ventricular tachycardia, including premature ventricular contractions, is an approved, albeit infrequent procedure in pediatric patients. Data are scarce regarding the outcomes of this procedure. The purpose of this study was to share a high-volume center experience and patient outcomes for catheter ablation of ventricular ectopy and ventricular tachycardia in pediatric population.MethodsData were retrieved from the institutional data bank. Outcomes over time were evaluated, and procedural details were compared.ResultsA total of 116 procedures were performed on 102 pediatric patients between July 2009 and May 2021 at the Rajaie Cardiovascular Medical and Research Center in Tehran, Iran. Ablation was not performed in 4 procedures (3.4%) due to high-risk substrates. Of the remaining 112 ablations performed, 99 (88.4%) were successful. However, one patient died due to a coronary complication. There were no significant differences observed in early ablation results based on patients' age, sex, cardiac anatomy, or ablation substrates (P > 0.05). Follow-up records were available for 80 procedures, and 13 (16.3%) of those experienced recurrence. During long-term follow-up, none of the variables mentioned above were statistically different between patients with or without arrhythmia recurrence.ConclusionThe overall success rate of pediatric ventricular arrhythmia ablation is favorable. We found no significant predictor for the procedural success rate concerning acute and late outcomes. Larger multicenter studies are needed to elucidate the predictors and outcomes of the procedure.     

Catheter Ablation of Idiopathic Premature Ventricular Contractions and Ventricular Tachycardias Originating from Right Ventricular Septum

Background

Idiopathic premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs) originating from the subtricuspid septum and near the His bundle have been reported. However, little is known about the prevalence, distribution, electrocardiographic characteristics and the efficacy of radiofrequency catheter ablation (RFCA) for the ventricular arrhythmias arising from the right ventricular (RV) septum. This study aimed to investigate electrocardiographic characteristics and effects of RFCA for patients with symptomatic PVCs/IVTs, originating from the different portions of the RV septum.

Methodology/Principal Findings

Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 29 patients with symptomatic PVCs/IVTs originating from the RV septum. Among 581 patients with PVCs/IVTs, the incidence of ventricular arrhythmias originating from the RV septum was 5%. Twenty (69%) had PVCs/IVTs from the septal portion of the tricuspid valvular RV region (3 from superoseptum, 15 from midseptum, 2 from inferoseptum), and 9 (31%) from the septal portion of the basal RV (1 from superoseptum, 4 from midseptum, 4 from inferoseptum). There were different characteristics of ECG of PVCs/VT originating from the different portions of the RV septum. Twenty-seven of 29 patients with PVCs/IVTs arising from the RV septum were successfully ablated (93.1% acute success).

Conclusions/Significance

ECG characteristics of PVCs/VTs originating from the different portions of the RV septum are different, and can help regionalize the origin of these arrhythmias. The septal portion of the tricuspid valvular RV region was the preferential site of origin. RFCA was effective and safe for the PVCs/IVTs arising from the RV septum.     

15例儿童心动过速性心肌病的诊疗体会

目的:探讨儿童完全性心动过速性心肌病(pTIC)的临床特点、治疗及预后。方法:回顾分析2009年1月至2016年10月安徽省儿童医院心内科收治的15例完全性心动过速性心肌病患儿的临床表现、心功能、心电图、心脏彩超的特点,观察心律失常控制后的心室率、心脏左室内径大小及心功能恢复情况。结果:15例pTIC患儿以室上性快速心律失常多见(14例),10例单纯药物治疗,3例接受射频消融转为窦性心律,2例失访。随访半年至3年与治疗前比较心室率明显下降[(116±27)次/分vs.(189±28)次/分]、NT-proBNP降低[(404±355)pg/mL vs.(6280±3155)pg/mL]、心脏左室舒张末内径变小[(3.12±0.48)cm vs.(3.69±0.70)cm]、左室射血分数升高[(57.9±9.3)%vs.(42.2±9.5)%]、改良ROSS评分下降[1(0-5)分vs.7(4-10)分]。结论:儿童pTIC由各种快速心律失常引起,心脏扩大和心功能障碍可完全恢复,早期识别、有效治疗的儿童pTIC长期预后良好。     

Sudden death and its predictors in myocardial infarction survivors in an Indian population

ObjectiveThis study was conducted to assess the incidence of sudden cardiac death (SCD) in post myocardial infarction patients and to determine the predictive value of various risk markers in identifying cardiac mortality and SCD.MethodsLeft ventricular function, arrhythmias on Holter and microvolt T wave alternans (MTWA) were assessed in patients with prior myocardial infarction and ejection fraction ≤ 40%. The primary outcome was a composite of cardiac death and resuscitated cardiac arrest during follow up. Secondary outcomes included total mortality and SCD.ResultsFifty-eight patients were included in the study. Eight patients (15.5%) died during a mean follow-up of 22.3 ± 6.6 months. Seven of them (12.1%) had SCD. Among the various risk markers studied, left ventricular ejection fraction (LVEF) ≤ 30% (Hazard ratio 5.6, 95% CI 1.39 to 23) and non-sustained ventricular tachycardia (NSVT) in holter (5.7, 95% CI 1.14 to 29) were significantly associated with the primary outcome in multivariate analysis. Other measures, including QRS width, heart rate variability, heart rate turbulence and MTWA showed no association.ConclusionsAmong patients with prior myocardial infarction and reduced left ventricular function, the rate of cardiac death was substantial, with most of these being sudden cardiac death. Both LVEF ≤30% and NSVT were associated with cardiac death whereas only LVEF predicted SCD. Other parameters did not appear useful for prediction of events in these patients. These findings have implications for decision making for the use of implantable cardioverter defibrillators for primary prevention in these patients.     

Role of implantable cardioverter defibrillators in the treatment of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an important cardiovascular disease with sudden cardiac death as the most devastating presentation. Implantable cardioverter defibrillators (ICD) are the optimal therapy for prevention of sudden death from ventricular tachycardia or fibrillation of any cause. While there is no controversy with implanting ICDs in patients who have already survived a cardiac arrest, identifying high-risk patients for primary prevention in this disease remains a challenge. Implanting ICDs in patients with HCM is an important clinical consideration since many individuals could achieve normal or near-normal lifespans with this protection.     

Mechanisms of Premature Ventricular Complexes Caused by QT Prolongation

QT prolongation, due to lengthening of the action potential duration in the ventricles, is a major risk factor of lethal ventricular arrhythmias. A widely known consequence of QT prolongation is the genesis of early afterdepolarizations (EADs), which are associated with arrhythmias through the generation of premature ventricular complexes (PVCs). However, the vast majority of the EADs observed experimentally in isolated ventricular myocytes are phase-2 EADs, and whether phase-2 EADs are mechanistically linked to PVCs in cardiac tissue remains an unanswered question. In this study, we investigate the genesis of PVCs using computer simulations with eight different ventricular action potential models of various species. Based on our results, we classify PVCs as arising from two distinct mechanisms: repolarization gradient (RG)-induced PVCs and phase-2 EAD-induced PVCs. The RG-induced PVCs are promoted by increasing RG and L-type calcium current and are insensitive to gap junction coupling. EADs are not required for this PVC mechanism. In a paced beat, a single or multiple PVCs can occur depending on the properties of the RG. In contrast, phase-2 EAD-induced PVCs occur only when the RG is small and are suppressed by increasing RG and more sensitive to gap junction coupling. Unlike with RG-induced PVCs, in each paced beat, only a single EAD-induced PVC can occur no matter how many EADs in an action potential. In the wide parameter ranges we explore, RG-induced PVCs can be observed in all models, but the EAD-induced PVCs can only be observed in five of the eight models. The links between these two distinct PVC mechanisms and arrhythmogenesis in animal experiments and clinical settings are discussed.     

Idiopathic Ventricular Tachycardia Arising From the Right Ventricular Apex

We present a rare case of idiopathic ventricular tachycardia arising from the right ventricular apex. The electrocardiographic and electrophysiological characteristics of this tachycardia are discussed.     

Dronedarone for Recurrent Ventricular Tachycardia: A Real Alternative?

Sustained ventricular tachycardia (VT) is an important cause of morbidity and sudden death in patients with dilated cardiomyopathy. Although ICD effectively terminate VT episodes and improve survival, shocks reduce quality of life, and episodes of VT predict increased risk of heart failure and death despite effective therapy. Patients suffering recurrent VT episodes remain a challenge. Antiarrhytmic therapy reduces VT episodes, but it is associated with serious adverse events, and disappointing efficacy. Catheter ablation has emerged as an important option to control recurrent VT, but major procedure-related complications, and even death, are still issues to concern. And even with these armamentaria, some patients still have recurrent VT episodes and ICD shocks. We report on a patient with non-ischemic dilated cardiomyopathy and recurrent ventricular tachycardia resistant to multiple antiarrhytmic agents, in whom dronedarone was effective in completely suppressing ventricular tachycardia episodes.