Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana.
Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana.
Am J Physiol Heart Circ Physiol. 2020 Jan 1;318(1):H11-H24. doi: 10.1152/ajpheart.00325.2019. Epub 2019 Nov 8.
Recognition that coronary blood flow is tightly coupled with myocardial metabolism has been appreciated for well over half a century. However, exactly how coronary microvascular resistance is tightly coupled with myocardial oxygen consumption (MV̇o) remains one of the most highly contested mysteries of the coronary circulation to this day. Understanding the mechanisms responsible for local metabolic control of coronary blood flow has been confounded by continued debate regarding both anticipated experimental outcomes and data interpretation. For a number of years, coronary venous Po has been generally accepted as a measure of myocardial tissue oxygenation and thus the classically proposed error signal for the generation of vasodilator metabolites in the heart. However, interpretation of changes in coronary venous Po relative to MV̇o are quite nuanced, inherently circular in nature, and subject to confounding influences that remain largely unaccounted for. The purpose of this review is to highlight difficulties in interpreting the complex interrelationship between key coronary outcome variables and the arguments that emerge from prior studies performed during exercise, hemodilution, hypoxemia, and alterations in perfusion pressure. Furthermore, potential paths forward are proposed to help to facilitate further dialogue and study to ultimately unravel what has become the Gordian knot of the coronary circulation.
半个多世纪以来，人们已经认识到冠状动脉血流与心肌代谢密切相关。然而，直到今天，冠状动脉微血管阻力与心肌耗氧量（MV̇o）之间的紧密耦联仍然是冠状动脉循环中最具争议的谜团之一。对于局部代谢控制冠状动脉血流的机制的理解，由于对预期的实验结果和数据解释的持续争论而受到阻碍。多年来，冠状动脉静脉 Po 通常被认为是心肌组织氧合的指标，因此也是心脏中产生血管扩张代谢物的经典拟议误差信号。然而，相对于 MV̇o 变化的冠状动脉静脉 Po 的解释相当微妙，本质上是循环的，并且受到仍然在很大程度上未被解释的混杂影响的影响。本综述的目的是强调在解释关键冠状动脉结果变量之间的复杂相互关系以及在运动、血液稀释、低氧血症和灌注压变化期间进行的先前研究中出现的论点时所遇到的困难。此外，还提出了潜在的前进道路，以帮助促进进一步的对话和研究，最终解开已经成为冠状动脉循环的戈尔迪之结。
