ATRIAL BASED PACING STIMULATION AND LEVEL OF MOBILITY (ABSALOM)

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 充血性心力衰竭(CHF)患者经常由于不能通过努力增加每搏量和心率而导致运动能力下降。医学治疗可以改善每搏量，但不会有利地改变运动过程中的加速速度或峰值心率。一种名为植入式除颤器(ICD)的设备已被证明可以通过终止潜在威胁生命的心律失常来防止CHF患者的死亡。这些设备还内置了起搏器，以防止心脏在休息时过慢，以及允许在运动期间加速心率的频率响应功能。这项研究的假设是，根据心力衰竭患者运动高峰时的耗氧量来衡量，运动中的频率响应性心房起搏将改善运动能力。为了验证这一假设，将使用随机控制交叉设计。30名患有双腔ICD、中度至重度充血性心力衰竭、没有永久起搏指征的患者，将仅被编程为心脏后备起搏一个月。然后，患者将被随机分为频率响应型心房起搏和持续的心室备用起搏。将抽取几瓶血液供以后使用，并要求患者填写一份评估生活质量的问卷。然后，患者将接受症状受限的心肺负荷测试。在心肺负荷测试后，患者将再次被编程为心室后备起搏。24小时后，患者将转换到相反的起搏模式，然后将重复前面描述的心肺负荷测试。患者的设备将保持第二次压力测试时的编程，最后一次压力测试将在三个月后进行。在最后一次访问中，患者将再次抽血，并被要求填写一份生活质量问卷。

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.