ATRIAL BASED PACING STIMULATION AND LEVEL OF MOBILITY (ABSALOM)

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Patients with congestive heart failure (CHF) frequently have diminished exercise capacity as the result of the inability to augment stroke volume and heart rate with exertion. Medical therapies can improve stroke volume, but do not favorably alter the rate of acceleration or peak heart rate during exercise. A device called an implantable defibrillator (ICD) has been shown to prevent death in patients with CHF by terminating potentially life-threatening arrhythmias. These devices also have built-in pacemakers to prevent the heart from going too slow during rest as well as rate-responsive features that allow for cardioacceleration during exercise. The hypothesis of this study is that rate-responsive atrial pacing during exertion will improve exercise capacity as measured by oxygen consumption at peak exercise in patients with CHF. To test this hypothesis, a randomized controlled crossover design will be used. Thirty patients with dual-chambered ICDs, moderate to severe congestive heart failure, and no indication for permanent pacing, will be programmed to ventricular back-up pacing only for one month. Patients will then be randomized to rate-responsive atrial pacing versus continued ventricular backup pacing. Several vials of blood will be drawn for later use and the patients will be asked to fill out a questionaire that assess quality of life. Patients will then undergo symptom-limited cardiopulmonary stress testing. Following the cardiopulmonary stress test, patients will once again be programmed to ventricular backup pacing. Twenty-four hours later, patients will crossover to the opposite pacing mode and cardiopulmonary stress testing as previously described will then be repeated. The patients devices will remain programmed as they were for the second stress test and a final stress test will be performed after three months. During this last visit, patients will once again have their blood drawn and be asked to fill out a quality of life questionaire.