Haude M, Caspari G, Baumgart D, Spiller P, Heusch G, Erbel R
Abteilung für Kardiologie, Universität-GHS Essen.
Herz. 1997 Apr;22(2):72-86. doi: 10.1007/BF03044306.
X-ray densitometric evaluation of digital subtraction coronary arteriograms allows a qualitative and quantitative detection of contrast medium propagation through the epicardial coronary arteries, the capillary system and the coronary venous system. So-called "time-density-curves" (TDCs) can be generated following Lambert-Beer's law similar to indicator dilution curves by using contrast medium as the indicator. Several time and density parameters can be derived from these TDCs, which are related to local myocardial perfusion. Different animal validation studies have shown the applicability of this concept for in-vivo evaluation of coronary blood flow and myocardial perfusion. Nevertheless, absolute measurement of volumetric coronary blood flow or myocardial perfusion failed. Therefore, relative changes in coronary blood flow or myocardial perfusion in response to pharmacologically induced maximum hyperemia were measured and coronary or myocardial perfusion reserve was calculated as the ratio of hyperemic flow or perfusion divided by baseline values. Despite theoretical attractions for an application during routine cardiac catheterization, this densitometric approach did not get a wide acceptance. Primary reason for this limited use in specialized centers was the time consuming process of densitometric evaluation of the subtraction coronary arteriograms, which require digital cine angiography and necessitates enormous computer hard ware. This main limitation has been overcome since more powerful computer hard ware (processor speed, hard disk space, digitization boards) has become rapidly available during the last years at more moderate pricing and digital techniques today are state of the art in cardiac catheterization laboratories. In addition, soft ware program packages allowed an automatization of the digitization and densitometric evaluation process. These programs include ECG triggered cine image digitization with improved temporal resolution, semiautomatic definition of regions-of-interest including definition of reference regions-of-interest for the detection of background density changes and quality-controlled densitometric parameter analysis. This progress made an application during routine cardiac catheterization feasible. In animal validation studies this improved X-ray densitometric approach for evaluation of local myocardial perfusion was validated versus colour-coded microsphere techniques. The time parameter "rise time", defined as the time from the start of local contrast medium induced density change to its maximum revealed a close correlation (r2 = 0.965) to the results of the microsphere technique over a wide range of perfusion. We have applied this technique before and after coronary interventions such as balloon angioplasty and stenting. Results documented an improvement of poststenotic myocardial perfusion reserve immediately after coronary balloon angioplasty and an additional improvement after adjunct coronary stenting. Only after stenting but usually not after coronary balloon angioplasty alone poststenotic myocardial perfusion reserve gained the intraindividual reference level, measured in a perfusion bed supplied by an epicardial coronary artery without stenoses. These results documented the functional benefit of coronary stenting on poststenotic myocardial perfusion in addition to the well known morphologic benefit with the creation of a larger and more circular conduit.
数字减法冠状动脉造影的X射线密度测定评估能够定性和定量检测造影剂通过心外膜冠状动脉、毛细血管系统和冠状静脉系统的传播情况。通过将造影剂用作指示剂，可依据朗伯-比尔定律生成所谓的“时间-密度曲线”（TDC），类似于指示剂稀释曲线。从这些TDC中可以得出几个与局部心肌灌注相关的时间和密度参数。不同的动物验证研究表明了这一概念在体内评估冠状动脉血流和心肌灌注方面的适用性。然而，冠状动脉血流容积或心肌灌注的绝对测量未能实现。因此，测量了药理学诱导的最大充血反应中冠状动脉血流或心肌灌注的相对变化，并将冠状动脉或心肌灌注储备计算为充血血流或灌注与基线值的比值。尽管在常规心脏导管插入术中应用具有理论吸引力，但这种密度测定方法并未得到广泛认可。在专业中心这种应用受限的主要原因是数字减法冠状动脉造影的密度测定评估过程耗时，这需要数字电影血管造影术且需要大量计算机硬件。自过去几年以来，由于更强大的计算机硬件（处理器速度、硬盘空间、数字化板）以更适中的价格迅速可用，且如今数字技术在心脏导管插入实验室中已成为主流，这一主要限制已被克服。此外，软件程序包实现了数字化和密度测定评估过程的自动化。这些程序包括具有改进时间分辨率的心电图触发电影图像数字化、半自动定义感兴趣区域，包括定义用于检测背景密度变化的参考感兴趣区域以及质量控制的密度测定参数分析。这一进展使得在常规心脏导管插入术中的应用成为可能。在动物验证研究中，这种改进的用于评估局部心肌灌注的X射线密度测定方法与彩色编码微球技术进行了对比验证。时间参数“上升时间”定义为从局部造影剂诱导密度变化开始到其最大值的时间，在广泛的灌注范围内与微球技术的结果显示出密切相关性（r2 = 0.965）。我们已在冠状动脉介入治疗（如球囊血管成形术和支架置入术）前后应用了该技术。结果表明，冠状动脉球囊血管成形术后即刻狭窄后心肌灌注储备有所改善，辅助冠状动脉支架置入术后进一步改善。仅在支架置入后，但通常在单独的冠状动脉球囊血管成形术后不会出现，狭窄后心肌灌注储备达到个体内参考水平，该参考水平是在由无狭窄的心外膜冠状动脉供血的灌注床中测量的。这些结果证明了冠状动脉支架置入术除了通过创建更大且更圆形的管道带来众所周知的形态学益处外，对狭窄后心肌灌注的功能益处。
