University of Louisville School of Medicine, Kentucky, USA.
ASAIO J. 2010 Sep-Oct;56(5):410-6. doi: 10.1097/MAT.0b013e3181e7bf3c.
Debate exists regarding the merits and limitations of continuous versus pulsatile flow mechanical circulatory support. To characterize the hemodynamic differences between each mode of support, we investigated the acute effects of continuous versus pulsatile unloading of the failing left ventricle in a bovine model. Heart failure was induced in male calves (n = 14). During an acute study, animals were instrumented through thoracotomy for hemodynamic measurement. A continuous flow (n = 8) and/or pulsatile flow (n = 8) left ventricular assist device (LVAD) was implanted and studied during maximum support ( approximately 5 L/min) and moderate support ( approximately 2-3 L/min) modes. Pulse pressure (PP), surplus hemodynamic energy (SHE), and (energy equivalent pressure [EEP]/mean aortic pressure (MAP) - 1) x 100% were derived to characterize hemodynamic energy profiles during the different support modes. Standard hemodynamic parameters of cardiac performance were also derived. Data were analyzed by repeated measures one-way analysis of variance within groups and unpaired Student's t-tests across groups. During maximum and moderate continuous unloading, PP, SHE, and (EEP/MAP - 1) x 100% were significantly decreased compared with baseline and compared with pulsatile unloading. As a result, continuous unloading significantly altered left ventricular peak systolic pressure, aortic systolic and diastolic pressure, +/-dP/dt, and rate x pressure product, whereas pulsatile unloading preserved a normal profile of physiologic values. As continuous unloading increased, the pressure-volume relationship collapsed, and the aortic valve remained closed. In contrast, as pulsatile unloading increased, a comparable decrease in left ventricular volumes was noted. However, a normal range of left ventricular pressures was preserved. Continuous unloading deranged the physiologic profile of myocardial and vascular hemodynamic energy utilization, whereas pulsatile unloading preserved more normal physiologic values. These findings may have important implications for chronic LVAD therapy.
关于连续与脉冲血流机械循环支持的优点和局限性存在争议。为了描述每种支持模式的血液动力学差异，我们在牛模型中研究了衰竭左心室连续与脉冲卸载的急性影响。在雄性小牛中诱导心力衰竭（n = 14）。在急性研究中，通过开胸术对动物进行器械检查以进行血液动力学测量。植入连续流（n = 8）和/或脉冲流（n = 8）左心室辅助装置（LVAD），并在最大支持（约 5 L/min）和中度支持（约 2-3 L/min）模式下进行研究。脉压（PP）、剩余血液动力学能量（SHE）和（能量等效压力[EEP]/平均主动脉压[MAP]-1）x 100%用于描述不同支持模式下的血液动力学能量曲线。还得出了心脏性能的标准血液动力学参数。数据通过组内重复测量单向方差分析和组间未配对学生 t 检验进行分析。在最大和中度连续卸载期间，与基线相比，PP、SHE 和（EEP/MAP-1）x 100%均显著降低，与脉冲卸载相比也是如此。因此，连续卸载显著改变了左心室收缩压峰值、主动脉收缩压和舒张压、+/--dp/dt 和率 x 压力乘积，而脉冲卸载保持了正常的生理值曲线。随着连续卸载的增加，压力-容积关系崩溃，主动脉瓣保持关闭。相反，随着脉冲卸载的增加，左心室容积呈可比下降。然而，保留了正常范围的左心室压力。连续卸载打乱了心肌和血管血液动力学能量利用的生理曲线，而脉冲卸载则保持了更正常的生理值。这些发现可能对慢性 LVAD 治疗具有重要意义。
