45 research outputs found
Should an abnormal serum potassium concentration be considered a correctable cause of cardiac arrest?
No full textAbstractAccording to American Heart Association/American College of Cardiology Practice Guidelines, electrolyte abnormalities, including abnormal serum potassium concentrations, are considered a correctable cause of a life-threatening ventricular arrhythmia. Ventricular defibrillator therapy in this situation is a class III indication, and thought to be ineffective and perhaps harmful, although there are minimal data to support this recommendation. The steady-state serum potassium concentration frequently changes during a cardiac arrest. Additionally, the vast majority of cardiac arrest patients have structural heart disease and are commonly treated with a variety of medications that can alter the serum potassium concentration. In the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients with a correctable cause of an electrolyte imbalance were excluded from study participation but were followed in the AVID registry. Similar outcomes were observed among patients in the AVID registry and the main trial. Spironolactone therapy in patients with congestive heart failure decreases all-cause mortality and sudden and nonsudden cardiac death. In a preliminary study of 169 patients with an episode of a sustained ventricular arrhythmia treated with an implantable defibrillator, freedom from appropriate defibrillator therapy was 18% after five years. The probability of appropriate defibrillator therapy was independent of the initial serum potassium concentration. For these reasons, our current clinical practice is to use an implantable defibrillator to treat an initial episode of sustained ventricular tachycardia or ventricular fibrillation that occurs in a patient with structural heart disease and an abnormal serum potassium concentration
Is defibrillation testing required for defibrillator implantation?
No full textAbstractThe assessment of defibrillation (DFT) efficacy has long been the standard of care during defibrillator implantation. To ensure an acceptable DFT safety margin, early defibrillator systems frequently required that the shock polarity and the location, type, or number of electrodes had to be altered. Advances in defibrillator and lead technology have resulted in lower and more consistent DFT thresholds in the range of 10 J, with an infrequent requirement to modify the DFT system. Yet, one can make an argument for and against continuation of DFT testing at the time of defibrillator implantation. The goal of this paper is to address both the data that do support and the data that do not support continuation of DFT testing at the time of device implantation. Scientifically, DFT testing should be abandoned only when prospective evidence demonstrates that defibrillator implantation without testing is as safe and has the same mortality benefits as implantation with testing. The most attractive aspect of eliminating DFT efficacy testing is that more patients may have the opportunity to be treated with this life-saving therapy. Perhaps there are alternative strategies to improve accessibility to defibrillator therapy without possibly eroding its effectiveness. In the end, will lives be saved or lost if we discontinue DFT efficacy testing and lower the barriers to implantable defibrillator therapy
Cost comparison of radiofrequency ablation and antiarrhythmic therapy of atrial flutter
No full textPermanent modification of A-V nodal function by selective intracoronary ethanol infusion in patients with refractory supraventricular tachycardia
No full textThe minimal energy requirements for transthoracic cardioversion of various types of atrial fibrillation
No full textMapping and ablation of ventricular tachycardia guided by virtual electrograms using a noncontact, computerized mapping system
No full textAbstractOBJECTIVESThe purpose of this study was to describe a computerized mapping system that utilizes a noncontact, 64 electrode balloon catheter to compute virtual electrograms simultaneously at 3,360 left ventricular (LV) sites and to assess the clinical utility of this system for mapping and ablating ventricular tachycardia (VT).BACKGROUNDMapping VT in the electrophysiology laboratory conventionally is achieved by sequentially positioning an electrode catheter at multiple endocardial sites.METHODSFifteen patients with VT underwent 18 electrophysiology procedures using the noncontact, computerized mapping system. A 9F 64 electrode balloon catheter and a conventional 7F electrode catheter for mapping and ablation were positioned in the LV using a retrograde aortic approach. Using a boundary element inverse solution, 3,360 virtual endocardial electrograms were computed and used to derive isopotential maps. An incorporated locator system was used in conjunction with or instead of fluoroscopy to position the conventional electrode catheter.RESULTSA total of 21 VTs, 12 of which were hemodynamically-tolerated and 9 of which were not, were mapped. Isolated diastolic potentials, presystolic areas, zones of slow conduction and exit sites during VT were identified using virtual electrograms and isopotential maps. Among 19 targeted VTs, radiofrequency ablation guided by the computerized mapping system and the locator signal was successful in 15.CONCLUSIONSThe computerized mapping system described in this study computes accurate isopotential maps that are a useful guide for ablation of hemodynamically stable or unstable VT
