Outcomes of catheter ablation in high-risk patients with Brugada syndrome refusing an implantable cardioverter defibrillator implantation

AIMS

The aim of this study was to investigate the outcomes of catheter ablation (CA) in preventing arrhythmic events among patients with symptomatic Brugada syndrome (BrS) who declined implantable cardioverter defibrillator (ICD) implantation.

METHODS AND RESULTS

A total of 40 patients with symptomatic BrS were included in the study, of which 18 refused ICD implantation and underwent CA, while 22 patients received ICD implantation. The study employed substrate modification (including endocardial and epicardial approaches) and ventricular fibrillation (VF)-triggering pre-mature ventricular contraction (PVC) ablation strategies. The primary outcomes were a composite endpoint consisting of episodes of VF and sudden cardiac death during the follow-up period. The study population had a mean age of 43.8 ± 9.6 years, with 36 (90.0%) of them being male. All patients exhibited the typical Type 1 BrS electrocardiogram pattern, and 16 (40.0%) were carriers of an SCN5A mutation. The Shanghai risk scores were comparable between the CA and the ICD groups (7.05 ± 0.80 vs. 6.71 ± 0.86, P = 0.351). Ventricular fibrillation-triggering PVCs were ablated in 3 patients (16.7%), while VF substrates were ablated in 15 patients (83.3%). Epicardial ablation was performed in 12 patients (66.7%). During a median follow-up of 46.2 (17.5-73.7) months, the primary outcomes occurred more frequently in the ICD group than in the CA group (5.6 vs. 54.5%, Log-rank P = 0.012).

CONCLUSION

Catheter ablation is an effective alternative therapy for improving arrhythmic outcomes in patients with symptomatic BrS who decline ICD implantation. Our findings support the consideration of CA as an alternative treatment option in this population.

Electrophysiological Characteristics and Ablation Outcomes in Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

BACKGROUND

Catheter ablation of premature ventricular contractions (PVCs) that trigger polymorphic ventricular tachycardia (PVT) or ventricular fibrillation has been reported as a novel therapy to reduce the syncope events in patients with catecholaminergic PVT, whereas the long-term ablation outcome and its value in improving exercise-induced ventricular arrhythmias remain unclear.

METHODS AND RESULTS

Fourteen consecutive selected patients with catecholaminergic PVT (mean±SD age, 16±6 years; 43% male patients) treated with maximum β-blockers with no possibility of adding flecainide were prospectively enrolled for catheter ablation. The primary end point was syncope recurrence, and the secondary end point was the reduction of the ventricular arrhythmia score during exercise testing. Twenty-six PVT/ventricular fibrillation-triggering PVCs were identified for ablation. The trigger beats arose from the left ventricle in 50% of the cases and from both ventricles in 36% of the cases. Purkinje potentials were observed at 27% of the targets. After a mean follow-up of 49 months after ablation, 8 (57%) patients were free from syncope recurrence. Ablation of trigger beat significantly reduced the syncope frequency (mean±SD, 4.3±1.6 to 0.5±0.8 events per year; P<0.001) and improved the ventricular arrhythmia scores at the 3-month (5 [range, 3-6] to 1.5 [range, 0-5]; P=0.002) and 12-month (5 [range, 3-6] to 2 [range, 0-5]; P=0.014) follow-ups. The induction of nontriggering PVCs postablation was closely associated with syncope recurrence (hazard ratio, 6.8 [95% CI, 1.3-35.5]; P=0.026).

CONCLUSIONS

Catheter ablation of PVT/ventricular fibrillation-triggering PVCs in patients with catecholaminergic PVT who cannot receive flecainide treatment seems to be a safe and feasible adjunctive treatment that may reduce the syncope burden and improve exercise-related ventricular arrhythmias. Induction of nontriggering PVCs after ablation is associated with a higher risk of syncope recurrence.

Complex repolarization dynamics in ex vivo human ventricles are independent of the restitution properties

AIMS

The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts.

METHODS AND RESULTS

We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel.

CONCLUSION

We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF.

Advances in Ventricular Arrhythmia Ablation for Brugada Syndrome

Three decades have passed since the Brugada syndrome (BrS) clinical entity was introduced in the early 1990s. During the first 2 decades, treatment of patients with BrS was challenging because there were limited treatment options, and an implantable cardioverter-defibrillator was the only choice for high-risk patients with BrS, that is, those who had aborted sudden cardiac death or had previous ventricular fibrillation episodes. In this article, the authors focus on these advances and how to treat patients with BrS with catheter ablation.

Long-term outcome after thoracoscopic cardiac sympathectomy for refractory ventricular tachyarrhythmia storm

A man in his 40s presented with an acute anterior wall myocardial infarction (MI) 6 hours after symptom onset to a non-percutaneous intervention enabled hospital and underwent thrombolysis with tenecteplase. His chest pain resolved post-thrombolysis although ST segment resolution was less than 50%. He had an episode of sustained ventricular tachycardia (VT) 48 hours after MI which was successfully cardioverted with 150 J biphasic shock. A month later he presented with a ventricular tachycardia storm that was refractory to pharmacological management. He underwent radiofrequency ablation of the VT using three-dimensional mapping. Although the patient remained free of VT/ventricular fibrillation (VF) for 48 hours, he had an episode of VF subsequently. A decision for bilateral surgical video assisted thoracoscopic cardiac sympathetic denervation was taken and the patient remained free of ventricular tachyarrhythmias after the procedure until.

Successful Catheter Ablation of the "R on T" Ventricular Fibrillation

In patients with idiopathic ventricular fibrillation (VF), recurrent implantable cardioverter-defibrillator (ICD) shocks might increase mortality risk and reduce patients’ quality of life. Catheter ablation of triggering ectopic beats is considered to be an effective method. We present a patient with recurrent VF, caused by the “R on T” premature ventricular complexes. In the presented case radiofrequency catheter ablation efficiently eliminated arrhythmia trigger, which was possible to detect thanks to the intracardiac electrocardiograms (ECG’s) stored in the ICD.

Right ventricular insertion promotes reinitiation of ventricular fibrillation in defibrillation failure

BACKGROUND

Shocks near defibrillation threshold (nDFT) strength commonly extinguish all ventricular fibrillation (VF) wavefronts, but a train of rapid, well-organized postshock activations (PAs) typically appears before sinus rhythm ensues. If one of the PA waves undergoes partial propagation block (wavebreak), reentry may be induced, causing VF to reinitiate and the shock to fail.

OBJECTIVE

The purpose of this study was to determine whether wavebreak leading to VF reinititation following nDFT shocks occurs preferentially at the right ventricular insertion (RVI), which previous studies have identified as a key site for wavebreak.

METHODS

We used panoramic optical mapping to image the ventricular epicardium of 6 isolated swine hearts during nDFT defibrillation episodes. After each experiment, the hearts were fixed and their geometry scanned with magnetic resonance imaging (MRI). The MRI and mapping datasets were spatially coregistered. For failed shocks, we identified the site of the first wavebreak of a PA wave during VF reinitiation.

RESULTS

We recorded 59 nDFT failures. In 31 of these, the first wavebreak event occurred within 1 cm of the RVI centerline, most commonly on the anterior side of the right ventricular insertion (aRVI) (23/31). The aRVI region occupies 16.8% ± 2.5% of the epicardial surface and would be expected to account for only 10 wavebreaks if they were uniformly distributed. By χ2 analysis, aRVI wavebreaks were significantly overrepresented.

CONCLUSION

The anterior RVI is a key site in promoting nDFT failure. Targeting this site to prevent wavebreak could convert defibrillation failure to success and improve defibrillation efficacy.

Stereotactic Cardiac Radiation to Control Ventricular Tachycardia and Fibrillation Storm in a Patient with Apical Hypertrophic Cardiomyopathy at Burnout Stage: Case Report

Stereotactic cardiac radiation for ablation (radioablation) of life-threatening ventricular arrhythmia was recently introduced into clinical practice. A 76-year-old male patient with apical hypertrophic cardiomyopathy at burnout stage, who received defibrillator implantation for the secondary prevention of sudden arrhythmic death, was admitted for repeated defibrillator therapy. Radiofrequency catheter ablation was unsuccessful due to the induction of ventricular fibrillation (VF) and hemodynamically unstable sustained monomorphic ventricular tachycardia (VT). However, intracardiac activation mapping for the induced VT revealed the earliest ventricular activation at the apical aneurysm. Radioablation was performed to control VT and VF storm refractory to antiarrhythmic drug therapy. A total of 24 Gray was radiated, divided into three fractions around the apical aneurysm. The onset of electrical modulation was instantaneous and the antiarrhythmic effect was maintained for at least 6 months without significant radiation toxicities. This case suggests that radioablation may be considered as a rescue therapy for VT and VF storm refractory to other treatment modalities.

Long-term outcomes of ablation for ventricular arrhythmias in mitral valve prolapse

PURPOSE

Prior studies reporting efficacy of radiofrequency catheter ablation for complex ventricular ectopy in mitral valve prolapse (MVP) are limited by selective inclusion of bileaflet MVP, papillary muscle only ablation, or short-term follow-up. We sought to evaluate the long-term incidence of hemodynamically significant ventricular tachycardia (VT) or fibrillation (VF) in patients with MVP after initial ablation.

METHODS

We studied consecutive patients with MVP undergoing ablation for complex ventricular ectopy between 2013 and 2017 at our institution. Of 580 patients with MVP, we included 15 (2.6%, 10 women; mean age 50 ± 14 years, 53% bileaflet) with complex ventricular ectopy treated with initial ablation.

RESULTS

Over a median follow-up of 3406 (1875-6551) days or 9 years, 5 of 15 (33%) patients developed hemodynamically significant VT/VF after their initial ablation and underwent placement of an implantable cardioverter defibrillator (ICD). Three of 5 also underwent repeat ablations. Sustained VT was inducible prior to index ablation in all 5 who developed VT/VF, compared to none of the 10 patients who did not develop VT/VF after index ablation (p = 0.002). Complex ventricular ectopy at index ablation was multifocal in all 5 patients who underwent repeat intervention versus 4 of 10 patients (40%) who did not (p = 0.04). All 3 patients with subsequent VT/VF who underwent repeat ablation had a new clinically dominant focus of ventricular arrhythmia and 3 of the patients with ICD had appropriate VT/VF therapies.

CONCLUSIONS

In the long term, a subset of MVP patients treated with ablation for ventricular arrhythmias, all with multifocal ectopy on initial EP study, develop hemodynamically significant VT/VF. Our findings suggest the progressive nature of ventricular arrhythmias in patients with MVP and multifocal ectopy.

Idiopathic Ventricular Fibrillation Manifesting Delta-wave during Hypothermia Treatment

We herein report a case of a 53-year-old man who survived cardiac arrest due to ventricular fibrillation (VF). When admitted to the hospital, his 12-lead electrocardiogram did not show Brugada-like ST elevation, early repolarization or delta-wave, in any leads. During the treatment of hypothermia, the manifestation of delta-wave was documented, which disappeared after the cessation of this treatment. A cardiac evaluation showed no structural heart disease, and electrophysiology studies did not demonstrate conduction via accessary pathway. Although the etiology of VF could not be determined, the most probable diagnosis was idiopathic VF. The patient was fitted with an implantable cardioverter-defibrillator.

Effectiveness of stellate ganglion blockade on refractory ventricular arrhythmias: a systematic review protocol

REVIEW QUESTION

The question of this review is: what is the effectiveness of stellate ganglion blockade on refractory ventricular arrhythmias in patients 18 years or over?

Epicardial radiofrequency catheter ablation of Brugada syndrome with electrical storm during ventricular fibrillation: A case report

RATIONALE

Brugada syndrome (BrS) is characterized by ST segment elevation at the J point ≥2 mm in the right precordial electrocardiogram (ECG) leads, in the absence of structural heart disease, electrolyte disturbances, or ischemia. It is a well-described cause of sudden death in young patients, especially in the age of between 30 and 40 years old. Here, we reported an unusual case of electrical storm (ES) of ventricular fibrillation (VF) caused by BrS with complete right bundle-branch block (CRBBB) in a 75-year-old male patient.

PATIENT CONCERNS

A 75-year-old male patient survived sudden cardiac death caused by a ventricular ES. He presented with the cove-shaped ST elevation of 2 mm in lead V1 with typical CRBBB and lacked structural cardiomyopathy and coronary heart disease. The patient suffered ventricular ES again, although the implantable cardioverter defibrillator(ICD) had implanted.

DIAGNOSES

Brugada syndrome with complete right bundle-branch block.

INTERVENTIONS

Implantable cardioverter defibrillator (ICD) implantation was performed. But this therapy could not prevent the recurrence of malignant arrhythmia. Finally, the ES was treated successfully using radiofrequency catheter ablation (RFCA) at the area of the free wall of the right ventricular outflow tract (RVOT) epicardium.

OUTCOMES

During 7 months of follow-up, the patient was asymptomatic and free of arrhythmic events.

LESSONS

As far as we know, the patient is the oldest patient reported to have BrS. RFCA offers an alternative therapy for patients with BrS, especially when ICD shocks are encountered.

Tolerance of Sustained Ventricular Fibrillation During Continuous-Flow Left Ventricular Assist Device Support

The widespread use of continuous-flow left ventricular assist devices for mechanical circulatory support has shown that long-term hemodynamic support is possible, even when a clinical "pulse" cannot be detected. We present the incidental discovery of ventricular fibrillation in 6 alert, hemodynamically stable patients supported only by a continuous-flow device (HeartMate II, n=5; Jarvik 2000, n=1). Ventricular fibrillation was found in 3 patients during routine outpatient follow-up visits and in 3 awaiting discharge from the hospital after device placement. Diagnosis was confirmed by electrocardiographic and echocardiographic studies. The average duration of mechanical circulatory support before ventricular fibrillation occurred was 221 ± 362 days (range, 5-864 d). All patients were conscious and ambulatory at the time of the arrhythmia. Three patients reported symptoms-primarily fatigue, nausea, and exertional dyspnea-that prompted evaluation. Serum chemistry analysis of blood drawn immediately after diagnosis showed no changes that suggested end-organ dysfunction. Three patients died of unrelated complications an average of 3.9 yr (range, 360-2,270 d) after the event. Two of the remaining 3 patients eventually underwent successful pump explantation, and one is on ongoing support. Our experience shows that it is possible for patients with continuous-flow left ventricular assist devices to remain hemodynamically stable while in ventricular fibrillation. Additional investigation is needed to determine whether defibrillator settings for these patients should be adjusted to limit delivery of shock therapy.

Effects of local cardiac denervation on cardiac innervation and ventricular arrhythmia after chronic myocardial infarction

Background

Modulation of the autonomic nervous system (ANS) has already been demonstrated to display antiarrhythmic effects in patients and animals with MI. In this study, we investigated whether local cardiac denervation has any beneficial effects on ventricular electrical stability and cardiac function in the chronic phase of MI.

Methods

Twenty-one anesthetized dogs were randomly assigned into the sham-operated, MI and MI-ablation groups, respectively. Four weeks after local cardiac denervation, LSG stimulation was used to induce VPCs and VAs. The ventricular fibrillation threshold (VFT) and the incidence of inducible VPCs were measured with electrophysiological protocol. Cardiac innervation was determined with immunohistochemical staining of growth associated protein-43 (GAP43) and tyrosine hydroxylase (TH). The global cardiac and regional ventricular function was evaluated with doppler echocardiography in this study.

Results

Four weeks after operation, the incidence of inducible VPC and VF in MI-ablation group were significantly reduced compared to the MI dogs (p<0.05). Moreover, local cardiac denervation significantly improved VFT in the infarcted border zone (p<0.05). The densities of GAP43 and TH-positive nerve fibers in the infarcted border zone in the MI-ablation group were lower than those in the MI group (p<0.05). However, the local cardiac denervation did not significantly improve cardiac function in the chronic phase of MI, determined by the left ventricle diameter (LV), left atrial diameter (LA), ejection fraction (EF).

Conclusions

Summarily, in the chronic phase of MI, local cardiac denervation reduces the ventricular electrical instability, and attenuates spatial heterogeneity of sympathetic nerve reconstruction. Our study suggests that this methodology might decrease malignant ventricular arrhythmia in chronic MI, and has a great potential for clinical application.

Prevalence and predictors of appropriate implantable cardioverter defibrillator therapy in chronic left ventricular dysfunction patients for primary prevention of sudden cardiac death in Siriraj Hospital

OBJECTIVE

The purpose of the present study was to identify the prevalence and predictors offirst appropriate implantable cardioverter defibrillator (ICD) therapy in patients with chronic LV dysfunction after placement of lCD for primary prevention.

MATERIAL AND METHOD

Retrospective design was used. Patients (n = 115) from Siriraj Hospitals with ischemic or non-ischemic cardiomyopathy who underwent ICD implantation for primary prevention were studied. Clinical data and ICD therapy data were obtained from medical records and lCD interrogation reports.

RESULTS

First appropriate ICD therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) were seen in 22 patients (19%) of whom 11 (9.5%) received lCD shock and 11 patients (9.5%) received anti-tachycardic pacing. Lack of beta-blocker use and lack ofaldosterone antagonist use were identified as significant predictors of appropriate therapy. There was no difference in prevalence of appropriate ICD therapy between ischemic and non-ischemic groups. The freedom from first appropriate therapy at 1, 2 and 3 years was 88%, 80% and 78%. The freedom rate was constant after the third year

CONCLUSION

Nearly one-fifth of chronic LV dysfunction patients with primary prevention ICD implantation experience appropriate ICD therapy. Most first appropriate ICD therapy occurs within 2 years after implantation. Lack ofbeta-blocker use and lack of aldosterone antagonist use were significant predictors of appropriate therapy.

[Catheter ablation for the treatment of electrical storm: methods and outcome]

Electrical storm imposes a negative effect on quality of life and increases patient mortality. Once antiarrhythmic drug therapy proves ineffective, catheter ablation becomes the therapy of choice. The preferred procedural endpoint following catheter ablation of ES is defined as lack of inducibility of any clinical or non-clinical ventricular arrhythmia. If successful, catheter ablation of ES can significantly lower patient mortality.

Catheter ablation of electrical storm in a patient with left ventricular assist device

Catheter ablation is an effective treatment for ventricular tachycardia (VT) in structural heart disease to reduce VT recurrence and implantable cardioverter defibrillator shocks.Current guidelines recommend ablation in patients with recurrent or incessant VT. In patients with left ventricular assist device (LVAD), VTs may be well tolerated hemodynamically and catheter ablation has been performed rarely, until now. We present a case of successful VT ablation in a patient with LVAD and electrical storm. Effective ablation after a transseptal LV access was achieved using electroanatomic mapping and a substrate-based approach. On the basis of this case, we discuss the pros and cons of VT ablation in these patients.

Epicardial ablation as a bailout in electrical storm?

Electrical storm (ES) is one of the most challenging clinical scenarios facing electrophysiologists, and in certain settings emergency ablation should be performed. The majority of ES occurs in patients with structural heart disease, predominantly coronary heart disease and nonischemic heart disease like right ventricular arrhythmogenic dysplasia and previous myocarditis as well as other cardiomyopathies. Implantable cardioverter-defibrillators (ICDs) are the first-line therapy in patients with ventricular tachycardia (VT) and structural heart disease. Recurrent VT episodes or ES are major problems in patients who receive an ICD after a spontaneous sustained VT. In addition, in patients with an ICD implanted for primary prevention of sudden cardiac death, 20 % will experience at least one VT episode within 3-5 years after ICD implantation. Catheter ablation has a high success rate in the acute setting in eliminating clinical VT. However, several factors make enodocardial catheter ablation of VT more difficult especially in advanced ischemic heart disease with heart failure and aneurysm. Frequently in nonischemic cardiomyopathies (NICM) there tends to be an epicardial and intramyocardial substrate where the critical VT zone can occasionally be epicardial or intramural in location. In some patients, an epicardial approach should be warranted first together with an endocardial approach or after failure of enodocardial ablation. Currently, the success rates of endocardial ablation in the acute setting are acceptable, but in the long term they are still not well defined. The purpose of this article is to highlight the importance of epicardial ablation as an alternative approach in controlling ES and to confirm the need for highly qualified centers to manage such challenging cases.

Catheter ablation in patients with electrical storm: benefit of a network of cooperating clinics

Catheter ablation has been shown to be an effective treatment for rhythm stabilization in patients with multiple ventricular arrhythmia episodes called electrical storm (ES). These procedures may be complex and are usually only performed in highly specialized and experienced centers. Still the optimum timing for catheter ablation in ES remains unclear.Early access to perform acute ablation should be considered in patients who are not rhythm stabilized with antiarrhythmic medical treatment. Also patients with hemodynamic compromise (cardiogenic shock) are candidates for an early interventional strategy. In specialized centers it is consensus to perform catheter ablation in these patients as early as eligible especially when considering a high early and late mortality without interventional management. Establishing a structured protocol for treatment and admission to EP centers has helped to further reduce pre-ablation mortality and may optimize treatment of ES. Large scale networking to optimize and structure access to experienced electrophysiology centers is of importance to create a basis for optimizing treatment strategies.

Intractable ventricular fibrillation: post ascending aortic dissection repair

Ascending aortic dissection is a life threatening surgical emergency and carries high peri-operative mortality. Various biological adhesive materials are commonly used in such a surgery to enhance strengthening of separated layers of aortic wall. Despite of extensive use, embolization of the glue material remains a feared complication. Here we are describing a case where BioGlue embolized down the left main stem and resulted in refractory ventricular arrhythmia and hemodynamic instability.

Multiform premature ventricular contractions and polymorphic ventricular tachycardia caused by Purkinje activity with slow conduction in idiopathic ventricular fibrillation

In several cases with idiopathic ventricular fibrillation (VF), VF was initiated by premature ventricular contractions (PVCs) from the Purkinje system. However, the precise characteristics of the Purkinje activity in patients with idiopathic VF remain unclear. We performed an electrophysiological study in a patient with idiopathic VF and examined the correlation between the Purkinje potential and the incidence of PVCs/polymorphic ventricular tachycardia (PMVT). In this case of idiopathic VF, the Purkinje activity caused multiform PVCs and PMVT. The The Purkinje activity and slow conduction of Purkinje fibers are associated with the occurrence of multiform PVCs and PMVT.

Suppression of ventricular fibrillation by electrical modification of the Purkinje system in hypertrophic cardiomyopathy

A 56-year-old man in hypertrophic cardiomyopathy had an electrical storm caused by ventricular fibrillation (VF). Mapping during the initiation of the VF triggered by a premature ventricular contraction (PVC1), with right bundle branch block (RBBB)-like morphology and superior axis, demonstrated a prominent Purkinje-muscle junction (PMJ) delay at the distal portion of the left posterior fascicle. Delivery of radiofrequency (RF) energy to this area abolished the VF triggered by the PVC1. However, VF emerged by triggering another PVC (PVC2) with RBBB-like morphology and inferior axis. Similarly, the initiation of VF was associated with the PMJ delay at the peripheral left anterior fascicle, where RF delivery completely suppressed the VF. The PMJ delay and subsequent Purkinje-muscle reentry-like activity could be essential for the initiation of the Purkinje-related VF.

[Radiofrequency ablation as acute treatment of ventricular arrhythmia]

The role of radiofrequency ablation in the acute management of electrical storm is reviewed. Electrical storm is defined as three or more intervention-requiring episodes of ventricular fibrillation or ventricular tachycardia within 24 hours. The management of electrical storm includes antiarrhythmic therapy including beta blockers and correction of initiating causes as myocardial ischaemia and electrolyte disturbances. Radiofrequency ablation provides an alternative in the management of electrical storm in the case of failure of the medical therapy.

Randomised comparison of percutaneous left ventricular assist device with open-chest cardiac massage and with surgical assist device during ischaemic cardiac arrest

AIMS

A percutaneous left ventricular assist device can maintain blood flow to vital organs during ventricular fibrillation and may improve outcomes in ischaemic cardiac arrest. We compared haemodynamic and clinical effects of a percutaneous left ventricular assist device with a larger device deployed via endovascular prosthesis and with open-chest cardiac massage during ischaemic cardiac arrest.

METHODS

Eighteen swine were randomised into three groups. After thoracotomy, coronary ischaemia and ventricular fibrillation was induced. Cardiac output was measured with transit-time flowmetry. Tissue perfusion was measured with microspheres. Defibrillation was performed after 20 min.

RESULTS

Cardiac output with cardiac massage was 1129 mL min⁻¹ vs. 1169 mL min⁻¹ with the percutaneous- and 570 mL min⁻¹ with the surgical device (P < 0.05 surgical vs. others). End-tidal CO₂ was 3.3 kPa with cardiac massage vs. 3.2 kPa with the percutaneous- and 2.3 kPa with the surgical device (P < 0.05 surgical vs. others). Subepicardial perfusion was 0.33 mL min⁻¹ g⁻¹ with cardiac massage vs. 0.62 mL min⁻¹ g⁻¹ with both devices (P < 0.05 devices vs. massage), cerebral perfusion was comparable between groups (all reported values after 3 min cardiac arrest, all P<0.05 vs. baseline, all P = NS for 3 min vs. 15 min). Return of spontaneous circulation was achieved in 5/6 subjects with cardiac massage vs. 6/6 with the percutaneous- and 4/6 with the surgical device (P = NS).

CONCLUSION

The percutaneous device improved myocardial perfusion, maintained cerebral perfusion and systemic circulation with similar rates of successful defibrillation vs. cardiac massage. Increased delivery was not obtained with the surgical device during cardiac arrest.

Mechanistic insights into initiation and maintenance of ventricular fibrillation: implications for catheter ablation

OBJECTIVE

This report is intended to provide an overview of the mechanism(s) of ventricular fibrillation (VF) and its relation to catheter ablation.

METHODS AND RESULT

We conducted a Pubmed and Medline literature search to identify all experimental and clinical studies published in English involving the mechanisms of VF and catheter ablation for VF. We found that controversies still exist with respect to the initiation and maintenance of VF despite more than a century of research due to the complexity of this arrhythmia and the limitation of the mapping technology. However, catheter ablation targeting the triggering factor for VF has been successfully applied in some patients who experience failure of drug therapy and frequent implanted cardiac defibrillator shocks.

CONCLUSIONS

VF is frequently triggered by short-coupled monophasic ventricular premature beats. VF is characteristic of partial and temporal organization instead of a state of completely aperiodic and disordered activation. Catheter ablation targeting the triggers for VF seems to be a safe and effective means for preventing VF in some patients.

A case report of central extracorporeal membrane oxygenation after implantation of a left ventricular assist system: femoral vein and left atrium cannulation for ECMO

PURPOSE

The left ventricular assist system (LVAS) is often used for end-stage heart failure. However, in severe lung disorder, the patient needs extracorporeal membrane oxygenation (ECMO) because oxygenation using only a ventricular assist system (VAS) is insufficient. We report a successful case of combining the use of LVAS and right VAS (RVAS) with ECMO.

METHOD

A 40-year-old female developed cardiogenic shock secondary to end-stage dilated cardiomyopathy, and percutaneous cardiopulmonary support (PCPS) was initiated. An echocardiogram showed a low ejection fraction (11%), and she underwent implantation of an LVAS (Toyobo Ventricular Assist System). She also required a RVAS with ECMO shunting between the right and left atrium because there was insufficient oxygenation resulting from pulmonary dysfunction followed by severe lung edema.

RESULT

Pulmonary function recovered successfully, and the RVAS-ECMO was removed after 7 days of support. There were no complications after operation, such as infection, bleeding, or systemic embolization.

CONCLUSION

LVAS combined with RVAS-ECMO in right and left atrial cannulation is a useful option for patients with severe pulmonary damage.

[Effect of shensongyangxin capsule on myocardial remodeling and ventricular fibrillation threshold value in rat with coronary artery ligation]

OBJECTIVE

To study the effect of shensongyangxin capsule on myocardial remodeling and ventricular fibrillation characteristics in rat with coronary artery ligation.

METHOD

Twenty-three male rats were randomly divided into sham-group (n = 5), model group (n = 6), anmiodarone group (n = 6) and shensongyangxin capsule group (n = 6). Drugs were administrated after modeling of 2 days, lasting four weeks. Two dimensional and Doppler images were acquired by a 15 MHz high-frequency linear ultrasound transducer at 4 weeks after operation, and chest was opened to detect ventricular fibrillation threshold value and persistent time.

RESULT

After administration of four weeks, echocardiogram was detected. Compared with model group, shensongyangxin capsule group diastasis interventricular septum thickness (IVSTd) and left ventricle diameter (LVDd) were significiently different between them (1.20 +/- 0.49) vs (0.78 +/- 0.08) mm and (6.77 +/- 1.34) vs (7.95 +/- 0.92) mm, (P < 0.01 and 0.05); echocardiogram result had no difference in amiodarone and model groups (P > 0.05). LVMI measured by practicion was different between shensongyangxin capsule and model groups: (17.12 +/- 1.91) vs (18.95 +/- 1.41) g x m(-2), (P < 0.05), while amiodarone group had no difference compared with model group. Electrophysiology was used to detect ventricular fibrillation threshold value and 1-5, 6-10, 11-15 V three stages' ventricular fibrillation threshold persistent time were significiently different among each group (P < 0.01), 16-20 V stage's ventricular fibrillation persistent time were also different among each group (P <0.05). Sample "average ranks" showed ventricular fibrillation threshold value of amiodarone group and shensongyangxin capsule group were four times than model group; and amiodaron group had best effect of holding-back ventricular fibrillation persistent time.

CONCLUSION

The coronary artery ligation can result in myocardial remodeling by increasing volume load, and at the same time influencing electrophysiology function of heart. Amiodaron elevated ventricular fibrillation threshold of heart, this effect maybe relate to influencing many ion channels of myocardial cellular membrane; shensongyangxin capsule also elevate ventricular fibrillation threshold of heart, this effect maybe also relate to influencing many ion channels of myocardial cellular membrane, and on the other hand this effect maybe relate to hold-back ventricular remodeling after coronary artery was ligated, accordingly improve electrophysiological base material of heart.

A computational study of mother rotor VF in the human ventricles

Sudden cardiac death is one of the major causes of death in the industrialized world. It is most often caused by a cardiac arrhythmia called ventricular fibrillation (VF). Despite its large social and economical impact, the mechanisms for VF in the human heart yet remain to be identified. Two of the most frequently discussed mechanisms observed in experiments with animal hearts are the multiple wavelet and mother rotor hypotheses. Most recordings of VF in animal hearts are consistent with the multiple wavelet mechanism. However, in animal hearts, mother rotor fibrillation has also been observed. For both multiple wavelet and mother rotor VF, cardiac heterogeneity plays an important role. Clinical data of action potential restitution measured from the surface of human hearts have been recently published. These in vivo data show a substantial degree of spatial heterogeneity. Using these clinical restitution data, we studied the dynamics of VF in the human heart using a heterogeneous computational model of human ventricles. We hypothesized that this observed heterogeneity can serve as a substrate for mother rotor fibrillation. We found that, based on these data, mother rotor VF can occur in the human heart and that ablation of the mother rotor terminates VF. Furthermore, we found that both mother rotor and multiple wavelet VF can occur in the same heart depending on the initial conditions at the onset of VF. We studied the organization of these two types of VF in terms of filament numbers, excitation periods, and frequency domains. We conclude that mother rotor fibrillation is a possible mechanism in the human heart.

[Changes in the spectral characteristics of ventricular fibrillation in lesions produced by radiofrequency ablation. An experimental study]

INTRODUCTION AND OBJECTIVES

Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions.

METHODS

Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compared.

RESULTS

In the ablated zones, significant reductions were observed in the spectral density of the dominant (0.168+/-0.113 mV(2)/Hz vs 0.025+/-0.018 mV(2)/Hz; P< .001) and mean frequencies (0.053+/-0.057 mV(2)/Hz vs 0.012+/-0.016 mV(2)/Hz; P< .001), the normalized energy around the dominant frequency (0.860+/-0.570 vs 0.128+/-0.091; P< .001), and the standard deviation of the power spectrum (0.031+/-0.020 mV(2)/Hz vs 0.004+/-0.001 mV(2)/Hz; P< .001). There was no significant change in the dominant (16.2+/-5.6 vs 14.8+/-1.8 Hz) or mean frequency (17.7+/-3.4 vs 16.6+/-1.3 Hz). The spectral parameters that could be used in a multivariate model to identify the lesion were the standard deviation of the power spectrum and the spectral density of the mean frequency.

CONCLUSIONS

During ventricular fibrillation, the spectral parameters associated with spectral power and spectral energy were significantly altered in zones with radiofrequency lesions and could be used to identify those zones. There was no significant change in either the dominant or mean frequency in these zones.

Twisting until it breaks: a rare cause of ICD lead failure

We describe a rare case of Twiddler's syndrome that resulted in a complex ICD lead fracture involving both the insulation and the conductor. The conductor fracture resulted in noise artefact that was interpreted by the device as ventricular fibrillation, but the patient had not received any shocks because the "episodes" were non-sustained. The patient did not have traditional risk factors for Twiddler's syndrome.

Management of ventricular arrhythmias

Underlying causes of ventricular tachycardia (VT) or complex ventricular arrhythmias (VA) should be treated if possible. This may include beta-adrenergic blockade radiofrequency catheter ablation and automatic implantable cardioverter-defibrillators. The ACC/AHA Class I indications for an AICD are discussed. Patients with AICDs should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing at a rate of 70/minute.

Prophylactic catheter ablation for the prevention of defibrillator therapy

BACKGROUND

For patients who have a ventricular tachyarrhythmic event, implantable cardioverter-defibrillators (ICDs) are a mainstay of therapy to prevent sudden death. However, ICD shocks are painful, can result in clinical depression, and do not offer complete protection against death from arrhythmia. We designed this randomized trial to examine whether prophylactic radiofrequency catheter ablation of arrhythmogenic ventricular tissue would reduce the incidence of ICD therapy.

METHODS

Eligible patients with a history of a myocardial infarction underwent defibrillator implantation for spontaneous ventricular tachycardia or fibrillation. The patients did not receive antiarrhythmic drugs. Patients were randomly assigned to defibrillator implantation alone or defibrillator implantation with adjunctive catheter ablation (64 patients in each group). Ablation was performed with the use of a substrate-based approach in which the myocardial scar is mapped and ablated while the heart remains predominantly in sinus rhythm. The primary end point was survival free from any appropriate ICD therapy.

RESULTS

The mortality rate 30 days after ablation was zero, and there were no significant changes in ventricular function or functional class during the mean (+/-SD) follow-up period of 22.5+/-5.5 months. Twenty-one patients assigned to defibrillator implantation alone (33%) and eight patients assigned to defibrillator implantation plus ablation (12%) received appropriate ICD therapy (antitachycardia pacing or shocks) (hazard ratio in the ablation group, 0.35; 95% confidence interval, 0.15 to 0.78, P=0.007). Among these patients, 20 in the control group (31%) and 6 in the ablation group (9%) received shocks (P=0.003). Mortality was not increased in the group assigned to ablation as compared with the control group (9% vs. 17%, P=0.29).

CONCLUSIONS

In this randomized trial, prophylactic substrate-based catheter ablation reduced the incidence of ICD therapy in patients with a history of myocardial infarction who received ICDs for the secondary prevention of sudden death. (Current Controlled Trials number, ISRCTN62488166 [controlled-trials.com].).

[Significance of the contralateral approach combined with venous deocclusion in a case of biventricular defibrillator implantation]

The authors report the case of a patient in whom a biventricular defibrillator was successfully implanted from the right, following a failed approach from the left. The patient had chronic thrombosis of the subclavian vein, and this procedure was only possible after venous deocclusion and the positioning of an endoprosthesis. The authors underline the significance of the contralateral approach in case of difficulties in inserting pacing devices, as well as the complementary benefits of interventional radiological procedures in order to allow vascular access in cases of chronic venous thrombosis.

Idiopathic Ventricular Fibrillation Successfully Terminated by Radiofrequency Ablation of the Distal Purkinje Fibers

A 21-year-old woman was admitted for evaluation of recurrent episodes of syncope. She had several spontaneous and abrupt loss of consciousness episodes while at the emergency department, caused by sustained and nonsustained ventricular fibrillation episodes. Each episode was initiated by a certain premature ventricular complex, which remained the same in subsequent ventricular fibrillation episodes. She had a total of eight more episodes of ventricular fibrillation during her admission, despite administration of intravenous antiarrhythmic agents. A diagnosis of idiopathic ventricular fibrillation was made. Radiofrequency catheter ablation was performed, targeting the distal Purkinje system. Ventricular fibrillation was noninducible after the procedure, and the patient has been symptom-free for the past 1 year.

Rare survival in a patient with severe complications of acute myocardial infarction: a case report

A 50-year-old man presented with acute myocardial infarction. Coronary angiography showed the left anterior descending artery (segment 6) was totally occluded. Direct percutaneous transluminal coronary angioplasty was performed, but a distal embolism occurred by the procedure. Consequently, he suffered cardiogenic shock and sustained ventricular tachycardia/fibrillation which exacerbated his condition. Finally, the patient was successfully treated with catheter ablation and cryosurgery to control the incessant ventricular arrhythmias, and partial left ventricular volume reduction and coronary artery bypass grafting to improve contractile performance. His left ventricular contractility did not improve, but the incessant ventricular arrhythmias could be controlled. His condition remarkably improved and he was discharged on foot. This patient with severe complications of acute myocardial infarction showed unusually good response and recovery.

Selective Myocardial Isolation and Ventricular Fibrillation

BACKGROUND

Few experimental studies have analyzed the effects of selective radiofrequency (RF) lesions upon ventricular fibrillation (VF). The RF-induced isolation of selected zones would make it possible to determine whether these zones are essential for existence of the arrhythmia.

METHODS

In 31 Langendorff-perfused rabbit hearts, the characteristics and inducibility of VF were analyzed before and after the induction of RF lesions comprising: (1) the posterior zone of the septum and of the walls of both ventricles (n = 10); (2) the anterior zone of the septum and of the walls of both ventricles (n = 11); and (3) the midseptal zone (n = 10).

RESULTS

Complete isolation of the zone encompassed by the lesions was obtained in 5, 6, and 5 experiments of series 1, 2, and 3, respectively. In these experiments, the arrhythmia was only induced from within the zone encompassed by the lesions in one experiment belonging to series 2 (P < 0.05 with respect to baseline). In contrast, in all but one of the cases in series 2, VF could be induced from outside the isolated zone (ns vs baseline). Partial isolation was obtained in five experiments of each series. In these experiments, on pacing from within the partially isolated zone, sustained VF was not induced in any experiment (P < 0.05 with respect to baseline), while in all cases VF could be induced on pacing from the external zone (ns vs baseline).

CONCLUSION

In the experimental model used, the three zones studied were not essential for maintaining VF. In most cases, their partial or total isolation avoided inducibility of the arrhythmia in those zones, though not in the remaining myocardium.