Active clinical trials for "Tachycardia"

The purpose of this research study is to examine the effect of percutaneous inferior cervical sympathetic block on life threatening abnormal heart rhythms called ventricular tachycardia or ventricular fibrillation that can lead to sudden cardiac death.

Cardiac arrest or sustained VT (ventricular tachycardia) in patients with heart disease is best treated with an ICD (implantable cardioverter defibrillator). However, the ICD alone is not appropriate therapy for patients with frequent VT episodes. In fact frequent shocks for VT may predict a poorer prognosis. Anti-arrhythmic drugs are co-administered with ICDs in up to 50% of patients to prevent VT episodes, but antiarrhythmic drugs may have harmful effects. Thus improved drugs to prevent VT without interfering with ICD function are needed. Recent data including our own suggest that clonidine may be a new therapy to prevent ICD shocks. It may act centrally on sympathetic outflow and peripherally and selectively on cardiac Purkinje, to suppress and control VT occurring in patients. Our purpose is to test the hypothesis that clonidine reduces frequent VT better than beta blocker in patients with ICDs. After informed consent patients will be randomized in a single blind fashion to either clonidine or metoprolol given three times per day. Other prescribed drugs may be adjusted to promote toleration of the study drug. ICD interrogations of episodes of VT will be the primary endpoint. Device based NIPS (non-invasive programmed stimulation) testing in a subset of these patients will allow mechanistic understanding of the clonidine effect. All of the procedural techniques are in place as performed clinically; preliminary data are given showing feasibility of the project.

The MADIT-II trial has shown that patients with severely reduced left ventricular ejection fraction (LVEF) post myocardial infarction benefit from the implantable cardioverter-defibrillator (ICD). However, retrospective analyses of the MADIT-II data have revealed a significantly increased morbidity and mortality in patients with appropriate ICD therapy: Appropriate ICD therapy is associated with 3.3-fold increased all-cause mortality, and the risk of a first heart failure hospitalization is 90% higher after 1st appropriate ICD therapy. Hence, the 1st appropriate therapy might indicate the necessity and utility of further clinical diagnostics and therapy in these patients. This trial is designed to (i) improve the knowledge of the group characteristics of patients suffering from 1st appropriate ICD therapy, (ii) but moreover to take additional therapeutic steps to reduce the mortality of this patient population.

The purpose of this study is to evaluate the clinical efficacy and safety of stereotactic ablative radiotherapy (SAbR), also known as stereotactic body radiation therapy (SBRT), for treatment of ventricular tachycardia (VT) requiring implantable cardioverter defibrillator (ICD) treatments in patients with VT refractory to standard invasive ablation techniques. We hypothesized that SAbR is effective in suppressing sustained VT and reducing ICD treatments in this group of patients and is associated with acceptably low risk of serious complications.

In this clinical investigation, the safety, feasibility and performance of the novel EnSite™ HD Grid Catheter mapping system for advanced high-density three-dimensional mapping will be studied in patients undergoing catheter ablation procedures for the treatment of non-paroxysmal atrial fibrillation (AF) or left atrial tachycardia (AT).

There is an increasing evidence regarding the efficacy of a substrate-based ablation approach to ventricular tachycardia (VT). This approach involves identifying regions of scar and also areas displaying late potentials and fractionated activity. Automated mapping systems are now available which may be able to generate high density maps displaying regions containing both late potentials and ventricular scar. Such an automated approach has not been validated. Furthermore, most patients presenting for VT ablation have pacing devices in situ. It is not known how the pacing modality affect the substrate maps generated for these procedures. Once an area felt to be important to ablate has been identified, the next key step is to perform effective ablation. An algorithm has now been made available (Ablation index - Biosense Webster Inc.,) which in preclinical studies is an effective predictor of radiofrequency lesion depth. This algorithm has been studied extensively in the atrium but not in the ventricle. This study would also seek to collect ablation index data during ablation to assess the algorithm during ventricular ablation.

Monophasic action potential (MAP) recording plays an important role in a more direct view of human myocardial electrophysiology under both physiological and pathological conditions. The MAP method represents a very useful tool for an electrophysiological research in cardiology. Its crucial importance lies in the fact that it enables the study of the action potential (AP) of myocardial cell in vivo and, therefore, the study of the dynamic relation of this potential with all the organism variables what can be particularly helpful in the case of arrhythmias. Hundred and fifty patients will be included to explore mapping capabilities in cardiac chambers in patients suffering from regular or fibrillating tachycardia's with the following inclusion plan: i) Atrial fibrillation at a total of 50 patients ii) Ventricular fibrillation or patients at high risk of sudden cardiac death at a total of 50 patients iii) Junctional tachycardia at a total of 50 patients. We will focus on cardiac activation (depolarization and repolarization) in this population.

The heart beat is controlled by electrical signals. Following a heart attack, part of the heart muscle dies and is later replaced by scar tissue. Within this area of scar, there often remain "channels" of surviving tissue still able to transmit electrical signals. However, it is well established that these "conduction channels" (CC) can form a short circuit around the scar, leading to electrical disturbances (arrhythmias) that are potentially life threatening. The commonest of these is ventricular tachycardia (VT), and is estimated to cause 300,000 deaths per year. One recognised treatment option of VT involves burning (ablation) these "conduction channels" (CC) within the scar. However, at present, the procedure is long and is far off 100% effective. Consequently, current best practice does not rely on treating the VT, but rather preventing it from causing sudden death - this is achieved with an Implantable Cardioverter Defibrillator (ICD), a device which can recognise when a patient is in VT and deliver an internal shock to restore the normal electrical conduction. Patients with defibrillators subsequently are subject to recurrent painful and debilitating shocks which, although lifesaving, significantly reduce their quality of life. The limitation with ablation at present is due to the difficulty in visualising these CC's. Investigators at Imperial College have created a novel electrogram visualisation program, Ripple Mapping (RM), which they have already found to be superior to currently used programmes in cases of arrhythmias in the upper chambers of the heart (the atria). During a retrospective study in patients with scar related VT following a heart attack, when ablation was delivered in areas associated with identified Ripple Mapping Conduction Channels, these patients remained free of VT recurrence for >2 year follow up interval. The study hypothesis is that Ripple Mapping can identify all conduction channels within scar tissue critical to the VT circuit, ablation of which will lead to long-term freedom from VT and ICD therapies. The investigators now aim to perform a prospective randomised study comparing Ripple Mapping guided VT ablation against conventional VT ablation.

We performed a prophylactic peroperative linear 1-minute cryolesion connecting the tricuspid annulus and right atriotomy to prevent IART on 15 consecutive adult patients undergoing surgery for congenital heart disease. Conduction time between electrodes placed on both sides of the cryolesion was measured on the second postoperative day. Coronary angiography and electrophysiology study using an electroanatomic mapping system to assess conduction across the line were performed three month after the operation on 13 patients.

To determine the antiarrhythmic effects of dietary N-3 fatty acids in patients with implanted defibrillators.