Analysis of cardiac lymphatic dynamics in beating canine hearts using a high-speed CCD microscope

控制心肌间质液非常重要，因为间质性水肿已被证明会损害心脏功能。为评价心脏淋巴管动力学，我们测量了心外膜淋巴管在一个心动周期内的时相性直径变化和流速波形。在10只麻醉开胸犬中，通过27号针头将印度墨水和悬浮液（Levovist）注射到左心室心尖部的心肌中，以分别观察淋巴网络和流速。在对照条件下，使用针透镜CCD显微镜在舒张末期和收缩末期通过印度墨水观察心脏收缩。使用高速CCD显微镜，根据Levovist悬液每5 ms的移动距离，通过帧到帧分析计算Levovist在心外膜血管中的流动速度。所有病例中，带瓣膜的淋巴管均清晰可见。心外膜血管直径由舒张末期的179 ± 47 μm增加到收缩末期的185 ± 44 μm，但无统计学意义。心脏淋巴液流速在收缩早期加快。收缩中期下降之后是收缩晚期，然后是舒张早期前向流。在舒张晚期，在某些情况下观察到反向流动。总之，由于心动周期中小的阶段性直径变化，心脏淋巴液的引流不受逐搏基础的控制。心脏淋巴流缓慢，但表现出独特的相位模式在心动周期。血流-速度模式表明，在收缩期心脏淋巴液动力学的主要决定因素可能是心肌应变和心肌内压力，由于心肌收缩。

Control of the interstitial fluid in the myocardium is very important, since interstitial edema has been demonstrated to impair cardiac function. To evaluate the cardiac lymphatic dynamics, we measured phasic diameter changes and flow velocity waveform of the epicardial lymphatics during a cardiac cycle. In 10 anesthetized open-chest dogs, India ink and suspension fluid (Levovist) were injected through a 27-gauge needle into the myocardium of the left ventricular apex for visualization of the lymphatic network and flow velocity, respectively. The cardiac lymphatics were visualized by India ink using a needle-lens CCD microscope at end-diastole and end-systole under control conditions. Velocities of Levovist flowing in the epicardial lymphatics were calculated by frame-to-frame analysis using a high-speed CCD microscope based on the moving distance of Levovist suspension per 5 ms. The lymph vessels with valves were clearly visualized in all cases. The diameters of epicardial lymphatics showed an increasing trend from 179 ± 47 μm at end-diastole to 185 ± 44 μm at end-systole without statistical significance. The cardiac lymph flow velocity was accelerated in early systolic phase. The mid-systolic dip was followed by late systolic and then early diastolic forward flow. A reverse flow was observed in some cases during late diastolic phase. In conclusion, because of small phasic diameter changes during a cardiac cycle, drainage of cardiac lymph is not controlled on a beat-to-beat basis. Cardiac lymphatic flow was slow but exhibited a unique phasic pattern during a cardiac cycle. Flow-velocity pattern indicated that major determinants of cardiac lymph dynamics during systole may be myocardial strain and intramyocardial pressure due to myocardial contraction.