Schmitz-Rode T, Kilbinger M, Günther R W
Universitätsklinikum der RWTH Aachen, Germany.
Cardiovasc Intervent Radiol. 1998 May-Jun;21(3):199-204. doi: 10.1007/s002709900244.
The flow pattern in the central pulmonary arteries proximal to large pulmonary emboli was studied experimentally. The currents to which thrombolytic agents are exposed when administered via an intrapulmonary catheter were visualized in order to explain the lack of benefit of local versus systemic administration.
By illumination of suspended microspheres, the flow pattern proximal to an obstructing embolus was visualized in an in vitro pulmonary arterial flow model. In six dogs massive pulmonary embolism was created. A pigtail catheter was positioned in the pulmonary artery immediately proximal to the central edge of the occluding embolus. To allow visualization of the local flow pattern, a small amount of contrast material (4 ml) was injected through the catheter at a high flow rate (25 ml/sec). The course of the radiopaque spot that emerged from the catheter tip within 160 msec was monitored with digital subtraction angiography at a frame rate of 12.5 frames/sec. In two dogs, the study was repeated after embolus fragmentation with the same catheter position.
The flow model study revealed formation of a vortex proximal to the occluding embolus. In vivo experiments showed that the radiopaque spot was whirled by the vortex proximal to the embolus and made only evanescent contact with the edge of the embolus. Regardless of the embolus location, the contrast spot was washed into the non-occluded ipsilateral and contralateral pulmonary arteries within 0.40-0.64 sec. After embolus fragmentation, the contrast spot was carried completely into the formerly occluded artery.
Flow studies explain why thrombolytic agents administered via a catheter positioned adjacent to the embolus may have no more effect than systemically administered agents. An enhanced local effect is precluded by the rapid washout into the non-occluded pulmonary arteries and subsequent systemic dilution. These results support the practice of direct intrathrombic injection of thrombolytics or local thrombolysis as an adjunct to embolus fragmentation.
对大型肺栓塞近端中央肺动脉内的血流模式进行实验研究。通过可视化经肺内导管给药时溶栓剂所接触的血流，以解释局部给药与全身给药效果差异的原因。
在体外肺动脉血流模型中，通过照亮悬浮微球来观察阻塞性栓子近端的血流模式。对6只犬造成大面积肺栓塞。将猪尾导管置于紧邻阻塞性栓子中心边缘的肺动脉内。为观察局部血流模式，以高流速（25 ml/秒）经导管注入少量造影剂（4 ml）。通过数字减影血管造影以12.5帧/秒的帧率监测导管尖端在160毫秒内出现的不透射线光斑的轨迹。在2只犬中，栓子破碎后在相同导管位置重复该研究。
血流模型研究显示在阻塞性栓子近端形成了一个涡流。体内实验表明，不透射线光斑被栓子近端的涡流旋转，仅与栓子边缘有短暂接触。无论栓子位置如何，造影剂光斑在0.40 - 0.64秒内被冲入未阻塞的同侧和对侧肺动脉。栓子破碎后，造影剂光斑完全进入先前阻塞的动脉。
血流研究解释了为何经紧邻栓子放置的导管给药的溶栓剂可能与全身给药的效果无异。快速冲入未阻塞的肺动脉并随后进行全身稀释，使得局部效果增强受到阻碍。这些结果支持了直接血栓内注射溶栓剂或局部溶栓作为栓子破碎辅助手段的做法。
