Active clinical trials for "Tachycardia"

The MADIT S-ICD trial is designed to evaluate if subjects with a prior myocardial infarction, diabetes mellitus and a relatively preserved ejection fraction of 36-50% will have a survival benefit from receiving a subcutaneous implantable cardioverter defibrillator (S-ICD) when compared to those receiving conventional medical therapy.

The chronic success rate, defined as freedom from any atrial tachyarrhythmias will increase from 35% to 60% by ablation of complex fragmented atrial electrograms potentials in addition to pulmonary vein isolation (PVI) as compared to PVI alone in patients with long-standing persistent AF.

The main limitation patients with orthostatic intolerance (OI, or postural tachycardia syndrome, POTS) have to exercise is related to their increase in heart rate when standing. Main pharmacological treatment today is aimed at reducing heart rate with the use of betablockers (propanolol), this theoretically could also improve their exercise capacity; if their heart rate do not increase as much with the medication, they could exercise more. In addition, it has been suggested that in healthy volunteers subjected to head down tilt for 2 weeks (situation that produces a "simulated" transient POTS-like state) a single bout of intense exercise can improve orthostatic tolerance the day after exercising. The mechanisms involved in such response are not that clear but could be an increase in plasma volume already diminished in POTS patients. It seems likely that the same could be true for POTS patients. The purpose of the present study are to pharmacologically improve the amount of exercise POTS patients can perform by reducing their baseline heart rate (specific aim 1) and to evaluate next day heart responses to an acute bout of intense exercise. Therefore, the specific aims of this study are: To test the hypothesis that lowering heart rate response with propanolol will result in an increase in exercise capacity. To test the hypothesis that a single bout of exercise will result in an improvement in orthostatic tolerance the day after exercising.

The purpose of this study is to determine if remote monitoring of implantable cardioverter defibrillators (ICD), compared with quarterly device interrogations in clinic, will improve patients' outcomes and satisfaction and will reduce health care costs.

The ASSURE Study will evaluate shock conversion performance when programming the first shock of an implantable cardioverter-defibrillation (ICD) is based on an implant test consisting of either 1) a single induction of ventricular fibrillation (VF) and subsequent demonstration conversion success at 14 J or 2) an upper limit of vulnerability (ULV) test at 14 J.

The DAVID II Clinical Study evaluates the hypothesis that, in patients needing an ICD but without overt indications for pacing, AAI pacing with maximal concomitant drug therapy will not increase the rate of the combined endpoint of mortality or hospitalization for new or worsened heart failure as compared to patients with ventricular backup pacing.

Study to compare non inferiority of giving adenosine with the simplified method vs the AHA method

Cardiac resynchronization therapy (CRT) is a proven therapy in patients with severe left ventricular (LV) dysfunction with ejection fraction (EF)<35%., moderate to severe congestive heart failure and wide QRS in ECG. Positive response presents as improvement in quality of life, decrease in congestive hrat failure symptoms and signs, improvements in echocardiographic measurements and longer survival. About 30% of the patients do not respond to this treatment. A decrease in clinical response to CRT is expected in patients with those predictors: advanced age, male, ischemic etiology of cardiomyopathy, Non-LBBB pattern in ECG, lack of mechanical dyssynchrony, large scar in LV, congestive heart failure stage IV, and non-cardiac co-morbidities (lung disease, pulmonary hypertension, renal failure and diabetes). There are few solutions to increase the rate of clinical response to CRT, for example: endocardial pacing of LV or pacing a few simultaneous sites on LV. A study that investigated a method of simultaneous pacing on LV of patients with congestive heart failure and LBBB with QRS>150ms has shown major improvement of cardiac contraction (increased dP/dtmax) compared to a single pacing site over a postero-basal or lateral wall site). Implantation of pacemaker leads- one in right ventricle (RV) and two over LV, i.e. multisite cardiac resynchronization therapy (MSCRT), has a few potential advantages, compared to conventional CRT.

With the increasing use of implantable cardioverter defibrillators (ICD) for primary prevention in patients with structural heart disease, an increasing number of patients are expected to develop their first episode of monomorphic ventricular tachycardia (VT) after an ICD is in place and the only documentation of the clinical arrhythmia will be the ICD electrogram (EG). The absence of a 12-lead ECG in patients with an ICD and sustained monomorphic VT represents a limitation when performing treatment with radiofrequency (RF) ablation. The analysis of ICD-EG during a RF ablation procedure is expected to provide a reference "model" of VT with clinical expression consisting of the electrical signal of the ICD during VT (which otherwise is not generally possible to obtain in ICD patients). This will allow for a more targeted approach to the substrate of the VT with clinical expression because: 1) if VT is induced by programmed stimulation, one can tell whether it is with clinical expression or not, and 2) if VT is not induced, ventricular pacing could be performed based on the comparative analysis of morphology and activation times of ICD-EG. These approaches will result in improved outcomes of the ablation procedure.

Some patients are at risk for life-threatening fast heart rates. These can frequently be treated by using a catheter inside the heart to burn away the cells that create the fast heart rates. The purpose of this study is to image the nerves inside the heart of those patients. The investigators want to find out if abnormalities in the nervous system in the heart can help the physician to find the area that needs to be burnt away.