CARDIAC OUTPUT WITH PACEMAKERS

建议创建一种实现所需的方法和装置 为植入的起搏器设置最佳频率。 该方法 适用于固定频率和运动反应起搏器， 采用心搏量和射血分数的连续测量， 通过在一对电极之间测量的阻抗变化来检测， 右心室的起搏导管 每搏输出量阻抗 变化（SVDeltaZ）通过单个 使用单次静脉注射的心输出量的测量 稀释盐水作为指示剂。 起搏上的附加电极 导管用于检测盐水稀释曲线。 稀释曲线 电极位于每搏输出量测量电极之间， 右心室（起搏）导管。 稀释曲线记录了 右心室血液电阻率的变化， 静脉注射稀释生理盐水指示剂。 稀释曲线为 通过了解血液流动的方式， 响应于盐水变化的电阻率变化（Δ P） 浓度（Deltac）;量Deltap/Deltac对于给定的浓度是特异性的。 物种 我们已经获得了狗和人的此类数据。心脏 然后将输出除以心率以获得真实的每搏输出量（SV）。 因此，SVDeltaZ根据真实SV进行校准;现在， 一拍一拍地提供。 将测定射血分数 根据SVDeltaZ与Zd的比值，其中Zd是右心室。 识别最佳起搏频率的方法包括绘制心脏起搏频率曲线。 输出（SVDeltaZ乘以起搏频率）与起搏频率。 这样的 曲线随着起搏频率的增加而上升到平台。 最佳起搏 速率是使曲线达到平台的最低速率。 一无所获 以更高的速度起搏。 在房室传导阻滞的犬中，将测定心输出量和射血分数。 由右心室阻抗变化得出。 心输出量将 与起搏频率作图。 射血分数（SVDeltaZ/Zd）也将 以评估其值，从而确定最佳的 起搏频率 将在正常静息和起搏条件下研究该手术 狗和狗在跑步机上进行适度和剧烈的运动。

It is proposed to create a method and the apparatus needed to enable setting the optimum rate for an implanted pacemaker. The method is applicable to fixed-rate, as well as exercise-responsive pacemakers and employs continuous measurement of stroke volume and ejection fraction, detected by the impedance change meaasured between a pair of electrodes on the pacing catheter in the right ventricle. The stroke volume impedance change (SVDeltaZ) is converted to true stroke volume (SV) by a single measurement of cardiac output using a single intravenous injection of dilute saline as the indicator. Additional electrodes on the pacing catheter are used to detect the saline dilution curve. The dilution-curve electrodes are located between the stroke-volume measuring electrodes on the right-ventricular (pacing) catheter. The dilution curve is a record of the change in resistivity of right-ventricular blood following the single intravenous injection of dilute saline indicator. The dilution curve is easily calibrated electrically by knowing the manner in which blood resistivity changes (Deltap) in response to a change of saline concentration (Deltac); the quantity Deltap/Deltac is specific for a given species. We have already obtained such data for dog and man. Cardiac output is then divided by heart rate to obtain true stroke volume (SV). Thus, the SVDeltaZ is calibrated in terms of true SV; now stroke volume is available on a beat-by-beat basis. Ejection fraction will be determined from the ratio of SVDeltaZ to Zd, where Zd is the right ventricle. The method of identifying the optimum pacing rate involves plotting cardiac output (SVDeltaZ multiplied by pacing rate) versus pacing rate. Such a curve rises to a plateau with increasing pacing rate. The optimum pacing rate is the lowest that brings the curve to the plateau. Nothing is gained by pacing at a higher rate. In dogs with A-V block, cardiac output and ejection fraction will be derived from the right-ventricular impedance change. Cardiac output will be plotted versus pacing rate. Ejection fraction (SVDeltaZ/Zd) will also be plotted versus pacing rate to assess its value to identify the optimum pacing rate. The procedure will be studied in normal resting and paced dogs and dogs exercising moderately and vigorously on the treadmill.