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

1964 ◽  
Vol 207 (3) ◽  
pp. 661-668 ◽  
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.

Local blood flow, oxygen tension, and oxygen consumption in the rat spinal cord

1983 ◽  
Vol 58 (4) ◽  
pp. 526-530 ◽  
Author(s):  
Nariyuki Hayashi ◽  
Barth A. Green ◽  
Mayra Gonzalez-Carvajal ◽  
Joseph Mora ◽  
Richard P. Veraa
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Tissue Oxygen ◽  
Local Blood Flow ◽  
Rat Spinal Cord ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Tissue Oxygen Consumption

✓ Using a reliable and reproducible microelectrode technique, consistent simultaneous measurements of local spinal cord blood flow (SCBF), tissue oxygen tension, and tissue oxygen consumption were made at cervical, thoracic, and lumbar levels in the rat spinal cord. These observations showed that the metabolic state is maintained constant along the cord, despite significant variations in vasculature. The physiological and anatomical aspects of these findings are discussed.

scholarly journals Changes in regional myocardial volume during the cardiac cycle: implications for transmural blood flow and cardiac structure

2008 ◽  
Vol 295 (2) ◽  
pp. H610-H618 ◽  
Author(s):  
Hiroshi Ashikaga ◽  
Benjamin A. Coppola ◽  
Katrina G. Yamazaki ◽  
Francisco J. Villarreal ◽  
Jeffrey H. Omens ◽  
...  
Keyword(s):  
Blood Flow ◽  
Volume Change ◽  
Time Course ◽  
Cardiac Cycle ◽  
Left Ventricular ◽  
Atrial Pacing ◽  
Canine Heart ◽  
Spatiotemporal Resolution ◽  
Tissue Pressure

Although previous studies report a reduction in myocardial volume during systole, myocardial volume changes during the cardiac cycle have not been quantitatively analyzed with high spatiotemporal resolution. We studied the time course of myocardial volume in the anterior mid-left ventricular (LV) wall of normal canine heart in vivo ( n = 14) during atrial or LV pacing using transmurally implanted markers and biplane cineradiography (8 ms/frame). During atrial pacing, there was a significant transmural gradient in maximum volume decrease (4.1, 6.8, and 10.3% at subepi, midwall, and subendo layer, respectively, P = 0.002). The rate of myocardial volume increase during diastole was 4.7 ± 5.8, 6.8 ± 6.1, and 10.8 ± 7.7 ml·min−1·g−1, respectively, which is substantially larger than the average myocardial blood flow in the literature measured by the microsphere method (0.7–1.3 ml·min−1·g−1). In the early activated region during LV pacing, myocardial volume began to decrease before the LV pressure upstroke. We conclude that the volume change is greater than would be estimated from the known average transmural blood flow. This implies the existence of blood-filled spaces within the myocardium, which could communicate with the ventricular lumen. Our data in the early activated region also suggest that myocardial volume change is caused not by the intramyocardial tissue pressure but by direct impingement of the contracting myocytes on the microvasculature.

Number and distribution of capillaries as determinants of myocardial oxygen tension

1964 ◽  
Vol 207 (3) ◽  
pp. 653-660 ◽  
Author(s):  
Wayne W. Myers ◽  
Carl R. Honig
Keyword(s):  
Oxygen Tension ◽  
Left Ventricular ◽  
Red Cells ◽  
Tissue Oxygen ◽  
Blood Content ◽  
Left Ventricular Apex ◽  
Plasma Skimming ◽  
Oxygen Tensions ◽  
Open Capillaries ◽  
Transmural Gradient

Blood content per gram of tissue was measured in various regions of the myocardium of the dog, by use of I131-labeled albumin and Cr51O4-labeled red cells. The ratio of I131 to Cr51O4 distributions was uniform, indicating that plasma skimming does not increase O2 delivery to the inner layers. Gradients in blood content were observed from epicardium to endocardium, and in the base-apex dimension of the heart. Both the transmural gradient and the amount of blood per gram of tissue were greatest at the left ventricular apex. In this region the deeper layers contained 1.5 times as much blood as superficial ones. The data permitted estimates of the number of open capillaries, and of intercapillary distances. These estimates indicate that only a fraction of the available capillaries are perfused at rest. Mean tissue oxygen tensions were computed for various conditions of flow, capillarity, and metabolism by use of the Kety modification of the Krogh equation. Results are discussed in relation to the regulation of tissue PO2.

Normal function of the cardiovascular system

2018 ◽  
Author(s):  
Manish Kalla ◽  
Neil Herring
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Cardiovascular System ◽  
Cardiac Cycle ◽  
Normal Function ◽  
Cardiac Physiology ◽  
Local Blood Flow ◽  
System P ◽  
Vascular Physiology ◽  
Flow Capillary

This chapter discusses normal function of the cardiovascular system, including cardiac physiology (the cardiac cycle, ECG, blood flow and heart sounds, control of cardiac output), vascular physiology (control of local blood flow, capillary transfer), integrated cardiovascular control,

Effects of Isoflurane on Regional Coronary Blood Flow and Myocardial Tissue Pressure in Chronically Instrumented Dogs

1994 ◽  
Vol 81 (4) ◽  
pp. 875-887 ◽  
Author(s):  
Young D. Kim ◽  
Kurt Heim ◽  
Yi-Ning Wang ◽  
David Lees ◽  
Adam K. Myers
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Myocardial Tissue ◽  
Tissue Pressure ◽  
Chronically Instrumented Dogs

Brain tissue pressure in focal cerebral ischemia

1985 ◽  
Vol 62 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Fausto Iannotti ◽  
Julian T. Hoff ◽  
Gerald P. Schielke
Keyword(s):  
Blood Flow ◽  
Pressure Gradient ◽  
Brain Tissue ◽  
Focal Cerebral Ischemia ◽  
Fluid Pressure ◽  
Artery Occlusion ◽  
Tissue Pressure ◽  
Edema Formation ◽  
Content Type ◽  
Ischemic Brain Edema

✓ Twenty-three anesthetized cats underwent permanent middle cerebral artery occlusion in a study of the relationships of regional cerebral blood flow, ventricular fluid pressure, brain tissue pressure, and ischemic edema formation. A pressure gradient of 8 mm Hg developed between ischemic tissue and normally perfused tissue during a 4-hour observation period after occlusion. Brain water accumulated as tissue pressure rose, while blood flow in the same area fell. The data suggest, but do not prove, that ischemic brain edema causes tissue pressure to rise focally, and that blood flow to the ischemic zone is compromised further by the resultant hydrostatic pressure gradient.

Sign in / Sign up

Export Citation Format

Share Document