自制微型轴流血泵对缺血后心脏左心辅助机制的实验研究

Experimental study on effects of self-made miniature axial flow blood pump on left ventricle assistance for postischemic heart

目的 应用自制微型轴流血泵对正常心脏及衰竭心脏进行辅助 ,探讨血泵的心脏辅助机制。方法 对 8只绵羊在心衰前后分别开关血泵进行自身比较 ,观察在正常和心衰时开关血泵对血流动力学指标的影响 ,并通过计算压力作功指数观察心肌耗氧量 (MVO2 )的变化。结果 心衰时 ,血泵能显著提高总心排量 [( 2 .6 9± 0 .16 )L/min ,与关泵时 ( 2 .30± 0 .15 )L/min比较 ,P <0 .0 1] ;血泵可以提高平均动脉压 (P <0 .0 0 1) ,在心脏正常时主要是由于舒张压的升高而引起的 ,与对照组比较 ,P <0 .0 1;心衰时血泵使收缩压和舒张压均显著升高 [( 85 .1± 3.5 )mmHg( 1mmHg =0 .133kPa)和 ( 80 .8± 5 .1)mmHg ,与关泵比较 ,P <0 .0 1] ;血泵显著降低了左室舒张末压和左房压 (P <0 .0 1) ,在心衰时可降低左室心肌最大收缩速度 (Dp/Dtmax) [( 333± 92 )mmHg/s ,P <0 .0 0 1] ,血泵显著降低了心脏左室外部作功和作功指数 ,减少了MVO2 ;在心衰时 ,当辅助流量占总心排量的 10 0 %时 ,MVO2 降低 48% ;结论 在不完全左心辅助时 ,主要通过减轻左室容量负荷减少左室MVO2 ;当达到完全辅助时 ,容量和压力负荷的减少均为左室MVO2 减少的原因 ,且此时MVO2 下降幅度最大为 48%。

Objective To investigate the mechanisms of left heart assistance with self made miniature axial flow blood pump in sheep.Methods After acute left heart failure was induced by selective ligation of the left anterior descending and circumflex branches of the coronary artery for 1.5 h in 8 adult healthy sheep, the effects of pump on was compared with pump off in normal hearts and in failure heart respectively to study the mechanisms of left heart assistance. Cardiac function was measured and pressure work index (PWI) was calculated to assess the changes in myocardial oxygen consumption (MVO 2).Results In normal heart, the blood pump could increase mean aortic pressure significantly by increasing diastolic aortic pressure [(85.1±3.3)?mm?Hg(1?mm?Hg=0.133?kPa),(80.8±5.1)?mm?Hg respectively, P<0.01].PWI was reduced significantly by decreasing left ventricular external work (LVEW) due to decreased volume load of left ventricle and increased diastolic aortic pressure, whereas total cardiac output and systolic pressure rate product (PRP) remained unchanged. In the presence of ischemic heart failure, the blood pump could increase total cardiac output [(2.69±0.16) L/min vs (2.30± 0.15) L/min] and mean aortic pressure, and decrease PWI and LVEW significantly. Left ventricular systolic pressure and PRP showed a decrease only when 100% assist ratio was achieved and at this time MVO 2 was deceased by 48%. Left ventricular end diastolic pressure and left atrial pressure showed a decrease in both heart conditions at pump on, left ventricular Dp/Dt max (333±92)?mm?Hg/s vs (851±170)?mm?Hg/s showed a decrease only in the presence of heart failure at pump on.Conclusion Left ventricular MVO 2 was reduced by volume unloading at incomplete circulatory support, while left ventricular MVO 2 was reduced by both volume and pressure unloading at complete circulatory support, and MVO 2 was reduced by 48% at this time.