Preliminary observations on blood flow in the coronary arteries of two school sharks (Galeorhinus australis)

1993 ◽  
Vol 71 (6) ◽  
pp. 1238-1241 ◽  
Author(s):  
Peter S. Davie ◽  
Craig E. Franklin
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Cardiac Cycle ◽  
Arterial Blood Flow ◽  
Ventricular Systole ◽  
Arterial Blood ◽  
Ventricular Mass ◽  
Aortic Blood Velocity

Coronary arterial blood flow and pressure, intraventricular blood pressure, and ventral aortic blood velocity were measured in two anaesthetized school sharks (Galeorhinus australis) in order to examine the phasic relationships between these flows and pressures. Maximum instantaneous flow recorded in the ventral coronary artery was 0.37 mL∙min−1∙kg−1 body mass (estimated 0.63 mL∙min−1∙g−1 ventricular mass). The average mean coronary blood flow was estimated as 0.28 mL∙min−1∙g−1 ventricular mass during periods of high coronary blood flow. On average, 86% of coronary flow occurred during diastole. Coronary arterial flow began during the last quarter of ventricular systole. Coronary blood flow peaked when intraventricular pressure fell to just below zero immediately after ventricular systole. Coronary blood flow fell slightly as diastole continued and reflected the small fall in coronary arterial pressure. Coronary flow reversed briefly during isovolumic ventricular contraction. Increases in the proportion of the cardiac cycle occupied by ventricular diastole, which occur during hypoxic bradycardia, have the potential to more than double coronary blood flow provided coronary arterial pressure is maintained.

Increased vascular resistance in paralyzed legs after spinal cord injury is reversible by training

2002 ◽  
Vol 93 (6) ◽  
pp. 1966-1972 ◽  
Author(s):  
Maria T. E. Hopman ◽  
Jan T. Groothuis ◽  
Marcel Flendrie ◽  
Karin H. L. Gerrits ◽  
Sibrand Houtman
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Cord Injury

The purpose of the present study was to determine the effect of a spinal cord injury (SCI) on resting vascular resistance in paralyzed legs in humans. To accomplish this goal, we measured blood pressure and resting flow above and below the lesion (by using venous occlusion plethysmography) in 11 patients with SCI and in 10 healthy controls (C). Relative vascular resistance was calculated as mean arterial pressure in millimeters of mercury divided by the arterial blood flow in milliliters per minute per 100 milliliters of tissue. Arterial blood flow in the sympathetically deprived and paralyzed legs of SCI was significantly lower than leg blood flow in C. Because mean arterial pressure showed no differences between both groups, leg vascular resistance in SCI was significantly higher than in C. Within the SCI group, arterial blood flow was significantly higher and vascular resistance significantly lower in the arms than in the legs. To distinguish between the effect of loss of central neural control vs. deconditioning, a group of nine SCI patients was trained for 6 wk and showed a 30% increase in leg blood flow with unchanged blood pressure levels, indicating a marked reduction in vascular resistance. In conclusion, vascular resistance is increased in the paralyzed legs of individuals with SCI and is reversible by training.

Quantification of O2 consumption and arterial pressure as independent determinants of coronary flow

1987 ◽  
Vol 252 (3) ◽  
pp. H545-H553 ◽  
Author(s):  
I. Vergroesen ◽  
M. I. Noble ◽  
P. A. Wieringa ◽  
J. A. Spaan
Keyword(s):  
Coronary Artery ◽  
Arterial Pressure ◽  
Coronary Flow ◽  
Left Main Coronary Artery ◽  
External Pressure ◽  
Arterial Blood Flow ◽  
O2 Consumption ◽  
Left Main ◽  
Arterial Blood ◽  
Wide Range

The steady-state relationship between coronary arterial blood flow (CBF) and both myocardial O2 consumption (MVO2) and coronary arterial pressure (P) was explored in anesthetized dogs and goats. Both species were subjected to constant pressure perfusion of the left main coronary artery by an external pressure-controlling circuit. In addition a group of goats was studied with normal aortic perfusion using an occluder around the left main coronary artery to vary coronary arterial pressure. The statistical analysis revealed that despite the direct effect of P on MVO2 (the Gregg effect) the effects of both variables on CBF were independent and linear over a wide range of P and MVO2 so that multiple regression analysis with a linear equation (CBF = a X P + b X MVO2 + c) gave an excellent fit which was not improved by the introduction of an addition interactive term b3MVO2 X P. The mean correlation coefficient for all animals was greater than 0.9. From these data we conclude that any factor regulating coronary arterial flow would be influenced by both MVO2 and perfusion pressure in an independent way. This study characterizes the stationary behavior of local coronary flow control. Hence, it specifies quantitatively the relations to be predicted by hypotheses aiming to explain this control mechanism.

Regulation of coronary flow

2021 ◽  
pp. 11-13
Author(s):  
Nico Bruining ◽  
Eric Boersma ◽  
Dirk J. Duncker
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Left Ventricular ◽  
Left Ventricular Wall ◽  
Ventricular Wall ◽  
Arterial Blood ◽  
Arterial Inflow ◽  
Systolic Phase ◽  
Vascular Beds

This chapter describes the regulation of coronary blood flow. The left ventricle generates the systemic arterial blood pressure that is required to maintain coronary blood flow. The coronary circulation is unique among regional vascular beds in that its perfusion is impeded during the systolic phase of the cardiac cycle by the surrounding contracting cardiac muscle. Systolic contraction increases left ventricular wall tension and compresses the intramyocardial microvessels, thereby impeding coronary arterial inflow. This compression is not uniformly distributed across the left ventricular wall, resulting in a redistribution of blood flow from the subendocardium to subepicardium.

INTERRELATIONSHIPS OF MATERNAL AND FETAL CIRCULATIONS

PEDIATRICS ◽  
1961 ◽  
Vol 27 (4) ◽  
pp. 627-635
Author(s):  
Forrest H. Adams ◽  
Nicholas Assali ◽  
Marjorie Cushman ◽  
Allan Westersten
Keyword(s):  
Blood Flow ◽  
Body Weight ◽  
Arterial Pressure ◽  
Umbilical Cord ◽  
Umbilical Vein ◽  
In Utero ◽  
Significant Rise ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Significant Change

Epinephrine and norepinephrine injected intravenously into pregnant ewes produced a prompt increase in maternal arterial pressure but a significant and sustained decrease in uterine arterial blood flow. Angiotensin injected intravenously into pregnant ewes produced a prompt increase in maternal arterial pressure (similar to epinephrine and norepinephrine) and an increase in uterine arterial blood flow. In the doses used, epinephrine, norepinephrine and angiotensin injected intravenously into pregnant ewes produced no significant observable effects on the arterial pressure and blood flow in the umbilical cord on heart rate in the fetus. Epinephrine and norepinephrine injected in the umbilical vein of lambs in utero produced a prompt and significant rise in umbilical arterial pressure and umbilical arterial flow only when large doses (five times effective adult doses/kg body weight) were used. Effective adult doses (kg body weight) injected into lambs in utero produced no significant change in arterial pressure or blood flow in the fetus. Angiotensin injected intravenously into lambs in utero produced no significant change in arterial pressure or blood flow in the umbilical cord. Vasoactive drugs injected into the mother on into the fetus did not appear to cross the placenta in either direction in physiologically effective amounts.

scholarly journals Obesity decreases the contribution of Kv channels to hypoxic coronary vasodilation

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Hannah E. Clark ◽  
Hana E. Baker ◽  
Adam G. Goodwill ◽  
Bianca S. Blaettner ◽  
Michael C. Kozlowski ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Functional Expression ◽  
K Channel ◽  
Coronary Vasodilation ◽  
Kv Channels ◽  
Arterial Blood ◽  
Before And After ◽  
Arterial Po2

Background and Hypothesis: Our group previously demonstrated that reductions in the functional expression of voltage-dependent K+ (Kv) channels contribute to impaired metabolic control of coronary blood flow in the setting of obesity. This study tested the hypothesis that obesity diminishes the contribution of Kv channels to coronary vasodilation in response to hypoxemia. Experimental Design or Project Methods: Control lean (n = 7) and obese (n = 5) swine were anesthetized and the heart exposed via left lateral thoracotomy. Coronary blood flow was measured in response to hypoxemia, before and after inhibition of Kv channels by 4-aminopyridine (4-AP; 0.3 mg/kg, iv), by a flow probe placed about the left anterior descending coronary artery. Hypoxemia was induced by progressive increases in the amount of nitrogen introduced into the ventilator. Arterial blood samples were obtained at each reduction in arterial oxygenation via a catheter placed in the femoral artery. Results: Blood pressure decreased from ~88 ± 5 mmHg to ~68 ± 6 mmHg (P = 0.01) as arterial PO2 was reduced below 50 mmHg in both lean and obese swine (P = 0.51). In lean swine, coronary flow progressively increased from ~0.6 to >3.0 ml/min/g as arterial PO2 was reduced. This response was decreased by ~40% in obese swine and by ~30% in lean swine treated with 4-AP. Administration of 4AP had no effect on coronary flow in obese swine. Conclusion and Potential Impact: These data support that Kv channels contribute to increases in coronary flow in response to hypoxemia in lean swine and that reductions in Kv channel function contribute to impaired hypoxic coronary vasodilation in obese swine. We propose that therapeutic targeting of obesity associated pathways (angiotensin-aldosterone system) known to influence K+ channel expression could improve coronary microvascular function and cardiovascular outcomes in subjects with obesity. Supported by R01 HL136386; T35 HL 110854.

Assessment of brachial artery blood flow across the cardiac cycle: retrograde flows during cycle ergometry

2002 ◽  
Vol 93 (1) ◽  
pp. 361-368 ◽  
Author(s):  
Daniel Green ◽  
Craig Cheetham ◽  
Chris Reed ◽  
Lawrie Dembo ◽  
Gerry O'Driscoll
Keyword(s):  
Blood Flow ◽  
Cardiac Cycle ◽  
Cycle Ergometry ◽  
Arterial Blood Flow ◽  
High Temporal Resolution ◽  
Ultrasound Images ◽  
Cross Sectional ◽  
Arterial Blood ◽  
Lower Limb Exercise ◽  
Automated Algorithms

We describe a novel software system that utilizes automated algorithms to perform edge detection and wall tracking of high-resolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, to calculate conduit arterial blood flow (BF) across the cardiac cycle. Furthermore, we describe changes in brachial arterial BF to the resting forearm during incremental cycle ergometry in eight subjects. During exercise, peak BF during the cardiac cycle increased at each workload ( P < 0.001), because of increased velocity in the presence of unaltered cross-sectional area. In contrast, mean BF calculated across each cardiac cycle decreased at lower workloads before increasing at 100 and 160 W ( P< 0.001). Differences in the pattern of peak and mean cardiac cycle flows were due to the influence of retrograde diastolic flow, which had a larger impact on mean flows at lower workloads. In conclusion, BF can be measured with high temporal resolution across the cardiac cycle in humans. Resting brachial arterial flow, including retrograde flow, increases during lower limb exercise.

Effect of portacaval surgical anastomosis on systemic and splanchnic hemodynamics in portal hypertensive, cirrhotic rats

1988 ◽  
Vol 66 (12) ◽  
pp. 1493-1498 ◽  
Author(s):  
José M. Romeo ◽  
Antonio López-Farré ◽  
Vicente Martín-Paredero ◽  
José M. López-Novoa
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Portal Pressure ◽  
Reference Sample ◽  
Arterial Blood Flow ◽  
Splanchnic Blood Flow ◽  
Portacaval Anastomosis ◽  
Systemic Hemodynamic ◽  
Hyperdynamic Circulation ◽  
Arterial Blood

The effect of surgical end-to-side portacaval anastomosis (PCSA) on systemic and splanchnic circulation has been studied in cirrhotic rats with portal hypertension (CCl4–Phenobarbital method) and in control animals. Hemodynamics have been measured using the microsphere technique, with a reference sample for the systemic hemodynamic measurements, and intrasplenic injection for portal systemic shunting rate measurements. Compared with controls, sham-operated (SO) cirrhotic rats showed a hyperdynamic circulation with increased cardiac output (CO) and decreased mean arterial pressure and peripheral resistances. PCSA in control rats induced only a small change in systemic hemodynamics, with parallel decreases in arterial pressure and peripheral resistances, and a small, nonsignificant increase in CO. In cirrhotic rats, PCSA induced a decrease of CO to values similar to those of control rats, with an increase in total peripheral resistances. PCSA induced an increase in hepatic arterial blood flow in control and in cirrhotic rats, portal pressure becoming in this latter group not different from that of control rats. Blood flow to splanchnic organs was higher in SO cirrhotic than in SO control animals. Thus portal venous inflow was also increased in SO cirrhotic rats. PCSA induced an increase in portal venous inflow in control rats, which was only significant in cirrhotic rats when expressed as a percentage of CO. In SO control animals, a significant correlation was observed between total peripheral resistances and splanchnic arteriolar resistances and between CO and splanchnic blood flow. These correlations were not observed in cirrhotic rats. These results do not support the hypothesis that hyperdynamic circulation shown by cirrhotic rats is based on increases in splanchnic blood flow and (or) massive portal systemic shunting.

scholarly journals Overview of mathematical modeling of myocardial blood flow regulation

2020 ◽  
Vol 318 (4) ◽  
pp. H966-H975
Author(s):  
Ravi Namani ◽  
Yoram Lanir ◽  
Lik Chuan Lee ◽  
Ghassan S. Kassab
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Oxygen Demand ◽  
Flow Regulation ◽  
Flow Reserve ◽  
Arterial Blood ◽  
Blood Flow Regulation ◽  
Highly Nonlinear ◽  
Coronary Flow Regulation

The oxygen consumption by the heart and its extraction from the coronary arterial blood are the highest among all organs. Any increase in oxygen demand due to a change in heart metabolic activity requires an increase in coronary blood flow. This functional requirement of adjustment of coronary blood flow is mediated by coronary flow regulation to meet the oxygen demand without any discomfort, even under strenuous exercise conditions. The goal of this article is to provide an overview of the theoretical and computational models of coronary flow regulation and to reveal insights into the functioning of a complex physiological system that affects the perfusion requirements of the myocardium. Models for three major control mechanisms of myogenic, flow, and metabolic control are presented. These explain how the flow regulation mechanisms operating over multiple spatial scales from the precapillaries to the large coronary arteries yield the myocardial perfusion characteristics of flow reserve, autoregulation, flow dispersion, and self-similarity. The review not only introduces concepts of coronary blood flow regulation but also presents state-of-the-art advances and their potential to impact the assessment of coronary microvascular dysfunction (CMD), cardiac-coronary coupling in metabolic diseases, and therapies for angina and heart failure. Experimentalists and modelers not trained in these models will have exposure through this review such that the nonintuitive and highly nonlinear behavior of coronary physiology can be understood from a different perspective. This survey highlights knowledge gaps, key challenges, future research directions, and novel paradigms in the modeling of coronary flow regulation.

Systemic and pulmonary vasomotor waves

1965 ◽  
Vol 209 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Ricardo Ferretti ◽  
Neil S. Cherniack ◽  
Guy Longobardo ◽  
O. Robert Levine ◽  
Eugene Morkin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Pulmonary Blood Flow ◽  
Breathing Pattern ◽  
Pulmonary Arterial Pressure ◽  
Arterial Blood Flow ◽  
Mayer Waves ◽  
Arterial Blood ◽  
Vasomotor Activity ◽  
Pulmonary Arterial

Rhythmic oscillations in systemic arterial blood pressure (Mayer waves) were produced in the dog by metabolic acidosis; hypoxia generally augmented the amplitude of the Mayer waves. When the Mayer waves exceeded 20 mm Hg in amplitude, they were associated with rhythmic fluctuations in pulmonary arterial pressure. The pulmonary arterial waves resembled the Mayer waves with respect to frequency and independence of the breathing pattern but were generally smaller in amplitude Measurements of instantaneous pulmonary arterial blood flow indicate that the rhythmic fluctuations in pulmonary arterial pressure represent the passive effects of fluctuations in pulmonary blood flow rather than fluctuations in pulmonary vasomotor activity. In turn, the swings in pulmonary arterial blood flow appear to originate in rhythmic variations in systemic vasomotor activity.

Sign in / Sign up

Export Citation Format

Share Document