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首页> 外文期刊>Artificial Organs >Derivation of Indices of Left Ventricular Contractility in the Setting of Continuous-Flow Left Ventricular Assist Device Support
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Derivation of Indices of Left Ventricular Contractility in the Setting of Continuous-Flow Left Ventricular Assist Device Support

机译：连续流左心室辅助装置支持设置中左心室收缩性指标的推导

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It is important to accurately monitor residual cardiac function in patients under long-term continuous-flow left ventricular assist device (cfLVAD) support. Two new measures of left ventricular (LV) chamber contractility in the cfLVAD-unloaded ventricle include I-Q, a regression coefficient between maximum flow acceleration and flow pulsatility at different pump speeds; and K, a logarithmic relationship between volumes moved in systole and diastole. We sought to optimize these indices. We also propose RIQ, a ratio between maximum flow acceleration and flow pulsatility at baseline pump speed, as an alternative to I-Q. Eleven patients (mean age 49 +/- 11 years) were studied. The K index was derived at baseline pump speed by defining systolic and diastolic onset as time points at which maximum and minimum volumes move through the pump. I-Q across the full range of pump speeds was markedly different between patients. It was unreliable in three patients with underlying atrial fibrillation (coefficient of determination R-2 range: 0.38-0.74) and also when calculated without pump speed manipulation (R-2 range: 0.01-0.74). The K index was within physiological ranges, but poorly correlated to both I-Q (P=0.42) and RIQ (P=0.92). In four patients there was excellent correspondence between RIQ and I-Q, while four other patients showed a poor relationship between these indices. As RIQ does not require pump speed changes, it may be a more clinically appropriate measure. Further studies are required to determine the validity of these indices.
机译：在长期连续流左心室辅助设备（cfLVAD）支持下，准确监测患者的残余心脏功能非常重要。 cfLVAD空载心室中左心室（LV）室收缩性的两个新指标包括I-Q，这是在不同泵速下最大流量加速度和流量脉动之间的回归系数;和K，收缩期和舒张期运动量之间的对数关系。我们试图优化这些指标。我们还提出了RIQ（基线泵速度下最大流量加速度与流量脉动率之比）作为I-Q的替代方案。研究了11名患者（平均年龄49 +/- 11岁）。通过将收缩压和舒张压发作定义为最大和最小体积通过泵的时间点，在基线泵速下得出K指数。患者之间在整个泵速范围内的I-Q明显不同。在三名潜在的心房颤动患者中（测定系数R-2范围：0.38-0.74）以及在不进行泵速操纵的情况下进行计算（R-2范围：0.01-0.74）时，该结果均不可靠。 K指数在生理范围内，但与I-Q（P = 0.42）和RIQ（P = 0.92）相关性很低。在四名患者中，RIQ和I-Q之间具有极好的对应关系，而其他四名患者则显示这些指数之间的关联性较差。由于RIQ不需要更改泵速，因此它可能是更临床上合适的措施。需要进一步研究以确定这些指标的有效性。

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