Correlation of the changes in diastolic myocardial tissue pressure and regional coronary blood flow in hemorrhagic and endotoxic shock

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 (MV̇o2) 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 Po2 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 Po2 relative to MV̇o2 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.

Download Full-text

Nonuniform distribution of blood flow and gradients of oxygen tension within the heart

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1964.207.3.661 ◽

1964 ◽

Vol 207 (3) ◽

pp. 661-668 ◽

Cited By ~ 186

Author(s):

Edward S. Kirk ◽

Carl R. Honig

Keyword(s):

Blood Flow ◽

Pressure Gradient ◽

Oxygen Tension ◽

Cardiac Cycle ◽

Myocardial Tissue ◽

Local Blood Flow ◽

Tissue Pressure ◽

Oxygen Tensions ◽

Sufficient Magnitude ◽

Transmural Gradient

Myocardial tissue pressure increases from epicardium to endocardium, and in the deeper layers exceeds ventricular blood pressure during one-third of the cardiac cycle (21). The effect of this tissue pressure gradient on local blood flow was studied using the depot clearance technique. Blood flow was found to be at least 25% lower in the deep regions as compared with superficial ones. With total coronary inflow held constant, vagal arrest of the heart removed the tissue pressure gradient, and simultaneously redistributed flow from superficial to deeper layers. We conclude that the gradient in tissue pressure, and hence in the extravascular component of coronary resistance, is at least in part, the cause of the nonhomogeneous blood flow across the wall. By use of the oxygen cathode, a gradient of oxygen tensions was observed which paralleled the blood flow gradient; mean oxygen tension in the subepicardium averaged twice that in the subendocardium. The gradient in oxygen tension appears to be of sufficient magnitude to determine a transmural gradient in aerobic metabolism.

Download Full-text

Felypressin-induced reduction in coronary blood flow and myocardial tissue oxygen tension during anesthesia in dogs

Canadian Journal of Anesthesia/Journal canadien d anesthésie ◽

10.1007/bf03013205 ◽

1999 ◽

Vol 46 (11) ◽

pp. 1070-1075 ◽

Cited By ~ 12

Author(s):

Hideharu Agata ◽

Tatsuya Ichinohe ◽

Yuzuru Kaneko

Keyword(s):

Blood Flow ◽

Coronary Blood Flow ◽

Oxygen Tension ◽

Tissue Oxygen Tension ◽

Myocardial Tissue ◽

Tissue Oxygen

Download Full-text

Feasibility of a New Non Invasive Method for the Evaluation of Coronary Blood Flow in the Left Anterior Descending Coronary Artery: Contrast-enhanced Transthoracic Harmonic Echo Doppler

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(97)84245-3 ◽

1998 ◽

Vol 31 (2) ◽

pp. 124A-125A ◽

Cited By ~ 1

Author(s):

C Caiati

Keyword(s):

Blood Flow ◽

Coronary Artery ◽

Coronary Blood Flow ◽

Non Invasive ◽

Contrast Enhanced ◽

Invasive Method

Download Full-text

METHODOLOGICAL ASPECTS OF VISUALIZATION OF CORONARY ARTERIES WITH TRANSTHORACIC ECHOCARDIOGRAPHY

Medical Visualization ◽

10.24835/1607-0763-2018-1-26-35 ◽

2018 ◽

pp. 26-35

Author(s):

Z. A. Agaeva ◽

K. B. Baghdasaryan

Keyword(s):

Blood Flow ◽

Coronary Blood Flow ◽

Coronary Arteries ◽

Transthoracic Echocardiography ◽

Second Harmonic ◽

Anatomic Reconstruction ◽

High Quality ◽

Acoustic Window ◽

Methodological Aspects

The transthoracic echocardiography made by multifrequency probes with support of the mode of the second harmonic imaging, is a competitive method for visualization of the main coronary arteries and allows to estimate coronary blood flow with high quality. Of course, the method has considerable restrictions, most important of which is the low spatial resolution of a method, due to small acoustic window. Because of this the transthoracic visualization of coronary arteries perhaps will not become the leading method of anatomic reconstruction of separately taken coronary artery and especially all coronary arteries system. However uniqueness and indisputable advantage of this method is an opportunity to noninvasively estimate a coronary blood flow both once, and in dynamics.

Download Full-text