ATRIAL BASED PACING STIMULATION AND LEVEL OF MOBILITY (ABSALOM)

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 充血性心力衰竭（CHF）患者经常由于无法增加每搏输出量和心率而导致运动能力下降。 药物治疗可以改善每搏输出量，但不能有利地改变运动期间的加速度或峰值心率。 一种被称为植入式除颤器（ICD）的设备已被证明可以通过终止可能危及生命的心律失常来预防CHF患者的死亡。 这些设备还具有内置的起搏器，以防止心脏在休息期间过慢，以及频率响应功能，允许在运动期间进行心脏加速。 本研究的假设是，心力衰竭患者在运动期间进行频率响应性心房起搏将改善运动能力（通过峰值运动时的耗氧量测量）。 为了检验这一假设，将使用随机对照交叉设计。 30例植入双腔ICD、中度至重度充血性心力衰竭且无永久起搏指征的患者将被程控为心室备用起搏，仅持续1个月。 然后将患者随机分配至频率响应心房起搏组和持续心室备用起搏组。 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，患者将接受限制性心肺压力测试。 心肺负荷试验后，患者将再次程控为心室备用起搏。 24小时后，患者将转换到相反的起搏模式，然后重复进行先前描述的心肺负荷测试。 第二次压力测试时，患者器械将保持程控状态，并在三个月后进行最终压力测试。 在最后一次访视期间，患者将再次抽血，并被要求填写生活质量问卷。

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.