Active clinical trials for "Tachycardia"

The aim of the study is to develop and validate a novel esophageal mapping system to improve the diagnostics of cardiac arrhythmias. Using a newly designed esophageal ECG catheter, esophageal ECGs (eECGs) will be recorded in 40 patients during an electrophysiological (EP) study and/or ablation procedure and in 12 healthy volunteers. In parallel acquired intracardiac electrograms will serve as reference for the developed mapping systems accuracy. Additionally, the esophageal mapping system will be compared to that of the standard 12-lead surface ECG in regard to its diagnostic performance.

Patients with POTS experience significant gastrointestinal symptoms. Current evidence suggesting that abnormal post-ganglionic sympathetic function could play a role in the pathophysiology of these GI abnormalities. Sympathetic fiber regulate motor and the postprandial GI peptides secretion. The focus of the present proposal is to determine glucose homeostasis, GI motility, and their association with GI and cardiovascular symptoms in POTS patients versus healthy controls. Furthermore, we will determine differences in these outcomes in POTS patients with and without evidence of postganglionic sympathetic fiber neuropathy. As a long-term goal, this study can lead us to understand the pathophysiology of common co-morbidities in patients with POTS to provide new treatment approaches and prevention strategies.

The purpose of this study is to see if people with Postural Tachycardia Syndrome (POTS) have different levels of certain chemicals in their blood than people who don't have POTS. This study will test whether the blood vessels of people with POTS will react differently to certain tests than people without POTS. The hypothesis of the study is: Patients with POTS will have vascular endothelial dysfunction compared with control subjects.

Rationale: Sudden cardiac death, mainly caused by ventricular arrhythmias (VA), is a major cause of morbidity and mortality in non-ischemic cardiomyopathy (NICM). Therapies that effectively prevent VA are lacking. Improved understanding of the substrate and mechanisms of VA in NICM may allow more effective, individualized and substrate-based therapies to be developed. In addition, risk stratification in NICM needs to be improved so that therapies can be allocated more efficiently. Objectives: 1) To improve our understanding of the underlying pro-arrhythmic substrate and electrophysiologic mechanisms of VA in NICM, and to develop individualized treatment for VA based on the identified substrate. 2) To improve risk stratification for VA and sudden cardiac death in NICM based on substrate characteristics. 3) to evaluate disease progression in NICM. Hypothesis: Improved understanding of the substrate and mechanisms of VA in NICM may allow more effective, individualized and substrate-based therapies to be developed. Study design: A prospective cohort study. Study population: The study population will consist of three groups (A, B and C): NICM patients with documented VA, suspected VA or intermediate to high risk for VA (according to established criteria) who are not referred for cardiac surgery (group A), NICM patients with documented VA, suspected VA or a high risk for VA who are referred for cardiac surgery (group B) and a control group consisting of patients without NICM who are referred for cardiac surgery (group C). Evaluation: All patients will be evaluated according to current standards for patients with NICM. Evaluation will include 24h-Holter, echocardiography, coronary angiogram and contrast-enhanced MRI (CE-MRI). If CE-MRI is performed in another hospital, additional recordings will be performed in our hospital. Additionally, blood samples (arterial, cardiac venous and peripheral venous) for collagen turnover markers will be taken from all patients. 123-iodine metaiodobenzylguanidine (123-I MIBG) imaging, electrophysiologic study and endomyocardial biopsy will be performed in group A and B. Intra-operative biopsy will be performed in group B and C. Intervention: In group B, intra-operative mapping and cryo-ablation and postoperative electrophysiologic study will be performed in patients with subepicardial late enhancement on MRI or induced VA suspected for an subepicardial origin. Main study parameters/endpoints: The main study parameters are extent, location and pattern of fibrosis on imaging and in biopsy specimens. The main study endpoints are inducibility of VA, type of induced VA, spontaneous VA and type of spontaneous VA.

Orthostatic intolerance refers to symptoms that occur with standing and improve or resolve with recumbency. Few studies have evaluated orthostatic intolerance symptoms by electroencephalography (EEG), and none of those studies have focused on the adolescent-aged patient. This study will compare EEG characteristics and sweat rate during head-upright tilt (HUT) testing among patients with postural tachycardia syndrome (POTS) and patients with syncope without POTS. Patients with POTS will also undergo a separate HUT with abdominal and lower extremity compression. The primary aim of this study is to characterize video EEG changes that correspond with orthostatic intolerance in youth during HUT testing. The investigators hypothesize that the clinical encephalopathy related to POTS and referred to as 'brain fog' will have an electrographic correlate. Secondary aims include (1) EEG comparisons of POTS symptoms with and without abdominal and lower extremity compression during HUT, (2) correlation between sweat rate and EEG changes during HUT, and (3) analysis of EEG characteristics that distinguish syncope with POTS from syncope without POTS. The investigators hypothesize that POTS patients have prolonged syncopal prodromes (compared to syncope patients without POTS) which are protective of syncope during daily activities.

Primary Objective: To characterize left ventricular (LV) threshold behavior over time using daily left ventricular capture management (LVCM) measurements. Study Design: This is a multicenter, prospective, non-interventional study with patients receiving their first cardiac resynchronisation therapy-implantable cardioverter defibrillator (CRT-ICD) device. The study design, based on the primary objective, is an observational examination of LV thresholds over time. Daily left ventricular threshold measurements will be collected using the LVCM feature. Up to 150 patients will be enrolled in Canada to evaluate the primary objective at up to 15 study centers. Data will be collected at Baseline, Implant, 12 months post-implant and all regularly scheduled follow-up visits up to 12 months post-implant. Devices: The ConcertoTM CRT-ICD device and future Medtronic CRT-ICD devices containing the LVCM feature will be used in this study.

The purpose is to further evaluate the operation, safety, and feasibility of a subcutaneous implantable defibrillator (S-ICD) system in patients who require an implantable cardioverter defibrillator (ICD)for treating ventricular tachyarrhythmias. The S-ICD electrode and pulse generator emulator will be briefly implanted and tested during the standard implantation procedure of an ICD, but then the S-ICD system will be removed entirely.

Analysis of the patients' data who were rescued with extracorporeal membrane oxygenation and without ECMO. The survival rate and the weaning rate were analyzed to see the effect of ECMO on the prolonged CPR.

The purpose of the Registry is to collect data on how Implantable Cardioverter Defibrillator (ICD) therapies and medications are being used by physicians to treat ventricular arrhythmias in order to better understand how to improve the clinical care of patients and effectiveness of ICD therapies.

The purpose of this study is to evaluate cognition in patients with postural tachycardia syndrome (POTS) while lying down and standing and to assess the prevalence of hypermobile Ehlers-Danlos Syndrome in POTS.