Mehlhorn U, Allen S J, Adams D L, Davis K L, Gogola G R, de Vivie E R, Laine G A
Department of Anesthesiology, University of Texas-Houston Medical School 77030, USA.
Circulation. 1995 Oct 1;92(7):1940-6. doi: 10.1161/01.cir.92.7.1940.
Normothermic continuous blood cardioplegia (BC) has been proposed to completely protect the myocardium during cardiac surgery. However, previous work from our laboratory suggests that BC could cause myocardial edema that produces cardiac dysfunction. The purpose of this present study was to evaluate the impact of BC on myocardial fluid balance and left ventricular function.
In 11 dogs, myocardial water content (MWC) was determined by microgravimetry. Myocardial lymph flow rate was measured after cannulation of the major prenodal cardiac lymphatic. Preload recruitable stroke work (PRSW) was calculated by sonomicrometry and micromanometry. The dogs were placed on normothermic cardiopulmonary bypass (CPB), and BC was delivered at either 80 to 90 mm Hg (BChigh; n = 6) or 40 to 50 mm Hg (BClow; n = 5) for 1 hour. Coronary sinus lactate and oxygen saturation monitoring demonstrated ischemia avoidance. BC was associated with substantial myocardial lymph flow rate decrease (P < .05) and myocardial edema development in both groups. MWC increased from 76.0 +/- 1.9% to 79.2 +/- 1.7% (P < .05) after 10 minutes of BChigh and from 75.9 +/- 0.6% to 78.9 +/- 1.4% (P < .05) after 30 minutes of BClow. PRSW decreased to 63 +/- 19% (BChigh) and 69 +/- 15% of control (BClow) at 30 minutes after CPB (P < .05). Myocardial lymph flow rate increases of threefold to fourfold that of control (P < .05) resulted in significant myocardial edema reduction associated with PRSW improvement to 71 +/- 17% (BChigh) and to 78 +/- 11% (BClow) at 2 hours after CPB.
We conclude that BC is associated with compromised cardiac function despite ischemia avoidance. This cardiac dysfunction is due to myocardial edema caused by the combination of increased myocardial microvascular fluid filtration and decreased myocardial lymph flow rate during BC.
常温持续血液停搏液（BC）已被提出用于在心脏手术期间完全保护心肌。然而，我们实验室之前的研究表明，BC可能会导致心肌水肿，进而引起心脏功能障碍。本研究的目的是评估BC对心肌液体平衡和左心室功能的影响。
在11只犬中，通过微量重力测定法测定心肌含水量（MWC）。在主要的结前心脏淋巴管插管后测量心肌淋巴流速。通过超声心动图和微测压法计算前负荷可募集搏功（PRSW）。将犬置于常温体外循环（CPB）下，以80至90 mmHg（高BC组；n = 6）或40至50 mmHg（低BC组；n = 5）给予BC 1小时。冠状窦乳酸和血氧饱和度监测显示避免了缺血。两组中BC均与心肌淋巴流速显著降低（P <.05）和心肌水肿形成相关。高BC组10分钟后MWC从76.0±1.9%增加到79.2±1.7%（P <.05），低BC组30分钟后MWC从75.9±0.6%增加到78.9±1.4%（P <.05）。CPB后30分钟，PRSW降至对照组的63±19%（高BC组）和69±15%（低BC组）（P <.05）。心肌淋巴流速增加至对照组的三到四倍（P <.05），导致CPB后2小时心肌水肿显著减轻，PRSW分别改善至71±17%（高BC组）和78±11%（低BC组）。
我们得出结论，尽管避免了缺血，但BC仍与心脏功能受损有关。这种心脏功能障碍是由于BC期间心肌微血管液体滤过增加和心肌淋巴流速降低共同导致心肌水肿所致。
