Bianco J A, Alpert J S
Department of Radiology, University of Wisconsin Medical School, Madison 53792-3252, USA.
Cardiology. 1997 Jan-Feb;88(1):116-26. doi: 10.1159/000177317.
In this essay we review data on absolute quantitation of myocardial blood flow (MBF) in humans. Earlier work established that coronary heart disease (CAD) can be detected by coronary angiography and that this disease has characteristic features at rest and during stress, which indicate the linkage between regional metabolic needs and myocardial perfusion. In the 1970s myocardial perfusion was mapped in patients with radioxenon, but this method had significant technical limitations. About the same time, radioactive microspheres were introduced for cardiovascular research and investigations; these particles provided insights on MBF in acute infarction and ischemia, myocardial reperfusion, collateral circulation, myocardial blood flow during exercise, coronary flow reserve (CFR), and layer-to-layer distribution of MBF. Studies with microspheres also permitted investigators to establish the presence in the heart of MBF heterogeneity. Currently, there are several techniques that aim at extending these concepts into clinical investigation. Two of these techniques, i.e. Doppler coronary flow velocity and fast magnetic resonance imaging assess epicardial flow dynamics and CFR. Contrast myocardial echocardiography is another novel technique which has been useful in mapping the area at risk, reperfusion, myocardial viability and collateral circulation. This essay also considers the emerging technique of intracoronary ultrasound which has shown evidence of disease underestimation by conventional contrast angiography. Positron emission tomography (PET) is a noninvasive technique that uniquely and quantitatively maps myocardial perfusion and CFR. The latter can be computed before and after angioplasty. PET studies have further demonstrated that chronic myocardial ischemia does not exist as a distinct state in patients with CAD. From the above investigations the concept has arisen that not only is CAD an entity involving epicardial vessels but also, in a significant portion of patients, an abnormal microcirculation plays an important role in the pathogenesis of ischemic syndromes. PET studies have relatively low spatial resolution since they cannot resolve layer-to-layer absolute MBF.
在本文中，我们回顾了关于人体心肌血流量（MBF）绝对定量的数据。早期研究证实，冠状动脉造影可检测出冠心病（CAD），且该疾病在静息和应激状态下具有特征性表现，这表明局部代谢需求与心肌灌注之间存在联系。20世纪70年代，用放射性氙对患者进行心肌灌注成像，但该方法存在重大技术局限。大约在同一时期，放射性微球被引入心血管研究；这些微粒为急性梗死和缺血、心肌再灌注、侧支循环、运动时的心肌血流量、冠状动脉血流储备（CFR）以及MBF的层间分布提供了见解。微球研究还使研究人员能够确定心脏中存在MBF异质性。目前，有几种技术旨在将这些概念扩展到临床研究中。其中两种技术，即多普勒冠状动脉血流速度和快速磁共振成像，用于评估心外膜血流动力学和CFR。对比心肌超声心动图是另一项新技术，在确定危险区域、再灌注、心肌存活能力和侧支循环方面很有用。本文还探讨了冠状动脉内超声这项新兴技术，它已显示出传统对比血管造影会低估疾病的证据。正电子发射断层扫描（PET）是一种无创技术，可独特且定量地绘制心肌灌注和CFR图。后者可在血管成形术前后进行计算。PET研究进一步证明，在CAD患者中，慢性心肌缺血并非一种独特的状态。从上述研究中产生了这样一种概念，即CAD不仅是一种涉及心外膜血管的疾病，而且在很大一部分患者中，异常的微循环在缺血综合征的发病机制中起重要作用。PET研究的空间分辨率相对较低，因为它们无法分辨层间绝对MBF。
