每日一题_2022.4.7

A 67-year-old man is admitted to the ICU after implantation of a continuous flow left ventricular assist device. Three days later, his device monitor displays a gradual increase in pump power from 4.3 to 6.7 watts, and the pulsatility index has decreased from 6.2 to 4.3. The speed set on the device is unchanged. Repeated laboratory values demonstrate an increased serum lactate dehydrogenase, increased serum total bilirubin, and a mixed venous oxygen saturation that has decreased from 62% to 49%.

Which of the following is the most likely explanation for these findings?

A. Popliteal vein thrombosis 

B. Acute mitral regurgitation 

C. Impeller thrombosis

D. Right ventricular failure

答案解析：

该患者器械可增加以不变速度驱动叶轮所需的功率，并降低搏动指数。搏动指数是患者自体左心室(LV)收缩对流经器械贡献的持续测量指标。叶轮血栓形成阻碍了最佳的叶轮功能，增加了达到设定速度所需的功率。此外，血流路径中存在血栓会减弱自体LV收缩对通过放送器的流量增加的贡献程度。这导致搏动指数降低。

血清乳酸脱氢酶(LDH)和总胆红素升高与红细胞溶血一致，这是泵血栓形成的标志。由于叶轮在产生血流方面的有效性较差，总心输出量可能降低，这可能导致混合静脉血氧饱和度(SmvO2)降低。腘静脉血栓形成可能会增加LDH和总胆红素，但不应改变功率需求或降低患者的混合静脉血氧饱和度。右心室衰竭可能降低SmvO2并增加总胆红素，但不会降低泵浦功率或增加LDH。同样，急性二尖瓣返流可能会降低SmvO2并增加总胆红素，但不会引起泵浦功率变化或LDH升高。与这些结果最一致的选择是叶轮血栓形成。

正确答案：C