Hyler Stefan, Pischke Søren E, Halvorsen Per Steinar, Espinoza Andreas, Bergsland Jacob, Tønnessen Tor Inge, Fosse Erik, Skulstad Helge
The Intervention Centre, Rikshospitalet, Oslo University Hospital, Oslo, Norway.
The Intervention Centre, Rikshospitalet, Oslo University Hospital, Oslo, Norway; Department of Anaesthesiology, Rikshospitalet, Oslo University Hospital, Oslo, Norway.
J Am Soc Echocardiogr. 2015 Apr;28(4):486-94. doi: 10.1016/j.echo.2014.12.014. Epub 2015 Jan 27.
Sensitive methods for the early detection of myocardial dysfunction are still needed, as ischemia is a leading cause of decreased ventricular function during and after heart surgery. The aim of this study was to test the hypothesis that low-grade ischemia could be detected quantitatively by a miniaturized epicardial ultrasound transducer (Ø = 3 mm), allowing continuous monitoring.
In 10 pigs, transducers were positioned in the left anterior descending and circumflex coronary artery areas. Left ventricular pressure was obtained by a micromanometer. The left internal mammary artery was grafted to the left anterior descending coronary artery, which was occluded proximal to the anastomosis. Left internal mammary artery flow was stepwise reduced by 25%, 50%, and 75% for 18 min each. From the transducers, M-mode traces were obtained, allowing continuous tissue velocity traces and displacement measurements. Regional work was assessed as left ventricular pressure-displacement loop area. Tissue lactate measured from intramyocardial microdialysis was used as reference method to detect ischemia.
All steps of coronary flow reduction demonstrated reduced peak systolic velocity (P < .05) and regional work (P < .01).The decreases in peak systolic velocity and regional work were closely related to the degree of ischemia, demonstrated by their correlations with lactate (R = -0.74, P < .01, and R = -0.64, P < .01, respectively). The circumflex coronary artery area was not affected by any of the interventions.
The epicardially attached miniaturized ultrasound transducer allowed the precise detection of different levels of coronary flow reduction. The results also showed a quantitative and linear relationship among coronary flow, ischemia, and myocardial function. Thus, the ultrasound transducer has the potential to improve the monitoring of myocardial ischemia and to detect graft failure during and after heart surgery.
由于缺血是心脏手术期间及术后心室功能下降的主要原因，因此仍需要用于早期检测心肌功能障碍的灵敏方法。本研究的目的是验证以下假设：使用小型化的心外膜超声换能器（直径 = 3毫米）可以定量检测低度缺血，从而实现连续监测。
对10头猪，将换能器置于左前降支和左旋冠状动脉区域。通过微测压计获取左心室压力。将左乳内动脉移植到左前降支冠状动脉，在吻合口近端进行阻断。左乳内动脉血流逐步减少25%、50%和75%，每次持续18分钟。从换能器获取M型轨迹，从而进行连续的组织速度轨迹和位移测量。将区域功评估为左心室压力 - 位移环面积。将心肌内微透析测得的组织乳酸用作检测缺血的参考方法。
冠状动脉血流减少的所有阶段均显示收缩期峰值速度降低（P < .05）和区域功降低（P < .01）。收缩期峰值速度和区域功的降低与缺血程度密切相关，与乳酸的相关性证明了这一点（分别为R = -0.74，P < .01和R = -0.64，P < .01）。左旋冠状动脉区域未受任何干预影响。
心外膜附着的小型化超声换能器能够精确检测不同程度的冠状动脉血流减少。结果还显示冠状动脉血流、缺血和心肌功能之间存在定量的线性关系。因此，超声换能器有潜力改善对心肌缺血的监测，并在心脏手术期间及术后检测移植物衰竭。
