scholarly journals A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise

2016 ◽  
Vol 310 (9) ◽  
pp. H1242-H1258 ◽  
Author(s):  
Christopher J. Arthurs ◽  
Kevin D. Lau ◽  
Kaleab N. Asrress ◽  
Simon R. Redwood ◽  
C. Alberto Figueroa
Keyword(s):  
Mathematical Model ◽  
Heart Rate ◽  
Blood Flow ◽  
Feedback Control ◽  
Coronary Blood Flow ◽  
Feedforward Control ◽  
Three Dimensional ◽  
Aortic Pressure ◽  
Oxygen Deficit ◽  
Patient Specific

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit.

Effect of indomethacin on coronary blood flow during graded treadmill exercise in the dog

1984 ◽  
Vol 247 (3) ◽  
pp. H452-H458 ◽  
Author(s):  
X. Z. Dai ◽  
R. J. Bache
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Arachidonic Acid ◽  
Coronary Blood Flow ◽  
Treadmill Exercise ◽  
Electromagnetic Flowmeter ◽  
Aortic Pressure ◽  
O2 Consumption ◽  
Vascular Response ◽  
Myocardial O2 Consumption

This study tested the hypothesis that metabolites of arachidonic acid may contribute to the coronary vascular response to physiological increases of myocardial O2 consumption that occur during exercise. Studies were performed in eight chronically instrumented dogs with electromagnetic flowmeter probes on the left circumflex coronary artery and aortic and coronary sinus catheters. Data were obtained at rest and during graded treadmill exercise during control conditions and after administration of the cyclooxygenase inhibitor indomethacin. During control conditions heart rate, aortic pressure, and coronary blood flow increased progressively during exercise; this was accompanied by a significant increase in myocardial O2 extraction, as evidenced by a decrease in coronary venous O2 tension (Po2) particularly during the first stage of exercise. Indomethacin (5 mg/kg iv) resulted in marked blunting of the coronary vasodilator response to intracoronary arachidonic acid in anesthetized open-chest dogs. After administration of indomethacin to awake dogs, resting heart rate, aortic pressure, and coronary venous Po2 were unaltered, and the response of these variables to exercise was not changed. The increase in coronary blood flow during exercise was also unchanged after indomethacin, so that the relationship between myocardial O2 consumption and coronary blood flow was unaltered by cyclooxygenase inhibition. Thus we were unable to demonstrate a significant effect of the prostaglandin system in mediating the coronary vascular response to exercise.

α-Adrenoceptor-mediated coronary vasoconstriction is augmented during exercise in experimental diabetes mellitus

2004 ◽  
Vol 97 (1) ◽  
pp. 431-438 ◽  
Author(s):  
Srinath Setty ◽  
Wei Sun ◽  
Rodolfo Martinez ◽  
H. Fred Downey ◽  
Johnathan D. Tune
Keyword(s):  
Diabetes Mellitus ◽  
Heart Rate ◽  
Blood Flow ◽  
Coronary Blood Flow ◽  
Aortic Pressure ◽  
Flow Transducer ◽  
Coronary Vasoconstriction ◽  
Before And After ◽  
The Difference ◽  
Diabetic Dogs

This study tested whether α-adrenoceptor-mediated coronary vasoconstriction is augmented during exercise in diabetes mellitus. Experiments were conducted in dogs instrumented with catheters in the aorta and coronary sinus and with a flow transducer around the circumflex coronary artery. Diabetes was induced with alloxan monohydrate ( n = 8, 40 mg/kg iv). Arterial plasma glucose concentration increased from 4.7 ± 0.2 mM in nondiabetic, control dogs ( n = 8) to 21.4 ± 1.9 mM 1 wk after alloxan injection. Coronary blood flow, myocardial oxygen consumption (MV̇o2), aortic pressure, and heart rate were measured at rest and during graded treadmill exercise before and after infusion of the α-adrenoceptor antagonist phentolamine (1 mg/kg iv). In untreated diabetic dogs, exercise increased MV̇o2 2.7-fold, coronary blood flow 2.2-fold, and heart rate 2.3-fold. Coronary venous Po2 fell as MV̇o2 increased during exercise. After α-adrenoceptor blockade, exercise increased MV̇o2 3.1-fold, coronary blood flow 2.7-fold, and heart rate 2.1-fold. Relative to untreated diabetic dogs, α-adrenoceptor blockade significantly decreased the slope of the relationship between coronary venous Po2 and MV̇o2. The difference between the untreated and phentolamine-treated slopes was greater in the diabetic dogs than in the nondiabetic dogs. In addition, the decrease in coronary blood flow to intracoronary norepinephrine infusion was significantly augmented in anesthetized, open-chest, β-adrenoceptor-blocked diabetic dogs compared with the nondiabetic dogs. These findings demonstrate that α-adrenoceptor-mediated coronary vasoconstriction is augmented in alloxan-induced diabetic dogs during physiological increases in MV̇o2.

Adenosine is not responsible for local metabolic control of coronary blood flow in dogs during exercise

2000 ◽  
Vol 278 (1) ◽  
pp. H74-H84 ◽  
Author(s):  
Johnathan D. Tune ◽  
Keith Neu Richmond ◽  
Mark W. Gorman ◽  
Ray A. Olsson ◽  
Eric O. Feigl
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Metabolic Control ◽  
Coronary Blood Flow ◽  
Myocardial Oxygen Consumption ◽  
Aortic Pressure ◽  
Receptor Blockade ◽  
Adenosine Concentration ◽  
Venous Plasma

The purpose of this investigation was to quantitatively evaluate the role of adenosine in coronary exercise hyperemia. Dogs ( n = 10) were chronically instrumented with catheters in the aorta and coronary sinus, and a flow probe on the circumflex coronary artery. Cardiac interstitial adenosine concentration was estimated from arterial and coronary venous plasma concentrations using a previously tested mathematical model. Coronary blood flow, myocardial oxygen consumption, heart rate, and aortic pressure were measured at rest and during graded treadmill exercise with and without adenosine receptor blockade with either 8-phenyltheophylline (8-PT) or 8- p-sulfophenyltheophylline (8-PST). In control vehicle dogs, exercise increased myocardial oxygen consumption 4.2-fold, coronary blood flow 3.8-fold, and heart rate 2.5-fold, whereas mean aortic pressure was unchanged. Coronary venous plasma adenosine concentration was little changed with exercise, and the estimated interstitial adenosine concentration remained well below the threshold for coronary vasodilation. Adenosine receptor blockade did not significantly alter myocardial oxygen consumption or coronary blood flow at rest or during exercise. Coronary venous and estimated interstitial adenosine concentration did not increase to overcome the receptor blockade with either 8-PT or 8-PST as would be predicted if adenosine were part of a high-gain, negative-feedback, local metabolic control mechanism. These results demonstrate that adenosine is not responsible for local metabolic control of coronary blood flow in dogs during exercise.

A model of combined feedforward and feedback control of coronary blood flow

1995 ◽  
Vol 268 (2) ◽  
pp. H895-H908 ◽  
Author(s):  
J. K. Miyashiro ◽  
E. O. Feigl
Keyword(s):  
Blood Flow ◽  
Feedback Control ◽  
Coronary Blood Flow ◽  
Feedforward Control ◽  
Receptor Activation ◽  
Balance Model ◽  
Feedback Gain ◽  
Beta Adrenergic ◽  
Beta Receptor ◽  
Flow Response

Recent evidence shows that norepinephrine affects coronary blood flow not only by alpha-receptor-mediated vasoconstriction and by feedback metabolic vasodilation that occurs as a result of myocardial beta-receptor activation, but also by the direct activation of coronary vascular beta-receptors that increase flow in a feedforward manner. The implications of combined feedforward and feedback control in maintaining the balance between metabolism and flow were investigated in the present mass balance model. Feedback was represented by a closed loop and was based on the hypothesis that the regulated variables are myocardial PO2 and PCO2 and that divergence of these variables from their operating point values functions as the metabolic error signals that manipulate coronary vascular smooth muscle and flow to match metabolism. alpha-Receptor-mediated vasoconstriction and beta-receptor-mediated vasodilation are represented by feedforward open loops that are activated simultaneously with increases in metabolism. The postulated control schemes of 1) metabolic feedback control alone, 2) feedback plus alpha- and beta-adrenergic feedforward control, and 3) feedback plus beta-adrenergic feedforward control were able to simulate the steady-state increase in coronary flow and the decrease in coronary venous PO2 that occurs during comparable experimental conditions. The simulations demonstrate that 1) the speed and accuracy of the flow response improve as beta-adrenergic feedforward control is added and alpha-adrenergic feedforward control is removed from the control scheme, 2) high feedback gain also improves the accuracy of the flow response, but the penalty is instability, and 3) a lag in alpha-adrenergic feedforward control improves the stability of the coronary response.

alpha-Adrenergic control of oxygen delivery to myocardium during exercise in conscious dogs

1982 ◽  
Vol 242 (5) ◽  
pp. H805-H809 ◽  
Author(s):  
G. R. Heyndrickx ◽  
P. Muylaert ◽  
J. L. Pannier
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Coronary Sinus ◽  
Oxygen Delivery ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Adrenergic Blockade ◽  
Adrenergic Control

alpha-Adrenergic control of the oxygen delivery to the myocardium during exercise was investigated in eight conscious dogs instrumented for chronic measurements of coronary blood flow, left ventricular (LV) pressure, aortic blood pressure, and heart rate and sampling of arterial and coronary sinus blood. After alpha-adrenergic receptor blockade a standard exercise load elicited a significantly greater increase in heart rate, rate of change of LV pressure (LV dP/dt), LV dP/dt/P, and coronary blood flow than was elicited in the unblocked state. In contrast to the response pattern during control exercise, there was no significant change in coronary sinus oxygen tension (PO2), myocardial arteriovenous oxygen difference, and myocardial oxygen delivery-to-oxygen consumption ratio. It is concluded that the normal relationship between myocardial oxygen supply and oxygen demand is modified during exercise after alpha-adrenergic blockade, whereby oxygen delivery is better matched to oxygen consumption. These results indicate that the increase in coronary blood flow and oxygen delivery to the myocardium during normal exercise is limited by alpha-adrenergic vasoconstriction.

scholarly journals Computational Analysis of Coronary Blood Flow: The Role of Asynchronous Pacing and Arrhythmias

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1205
Author(s):  
Timur Gamilov ◽  
Philipp Kopylov ◽  
Maria Serova ◽  
Roman Syunyaev ◽  
Andrey Pikunov ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Coronary Blood Flow ◽  
Long Qt Syndrome ◽  
Premature Ventricular Contraction ◽  
Cardiac Pacing ◽  
Long Qt ◽  
Computational Evaluation ◽  
Qt Syndrome

In this work we present a one-dimensional (1D) mathematical model of the coronary circulation and use it to study the effects of arrhythmias on coronary blood flow (CBF). Hydrodynamical models are rarely used to study arrhythmias’ effects on CBF. Our model accounts for action potential duration, which updates the length of systole depending on the heart rate. It also includes dependency of stroke volume on heart rate, which is based on clinical data. We apply the new methodology to the computational evaluation of CBF during interventricular asynchrony due to cardiac pacing and some types of arrhythmias including tachycardia, bradycardia, long QT syndrome and premature ventricular contraction (bigeminy, trigeminy, quadrigeminy). We find that CBF can be significantly affected by arrhythmias. CBF at rest (60 bpm) is 26% lower in LCA and 22% lower in RCA for long QT syndrome. During bigeminy, trigeminy and quadrigeminy, respectively, CBF decreases by 28%, 19% and 14% with respect to a healthy case.

scholarly journals Model-Based Design Approach to Improve Performance Characteristics of Hydrostatic Bearing Using Multivariable Optimization

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 388
Author(s):  
Waheed Ur Rehman ◽  
Xinhua Wang ◽  
Yiqi Cheng ◽  
Yingchun Chen ◽  
Hasan Shahzad ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Feedback Control ◽  
External Load ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Spindle Speed ◽  
Performance Criteria ◽  
Model Based ◽  
Hydrostatic Bearings ◽  
Robust Control Design

Research in the field of tribo-mechatronics has been gaining popularity in recent decades. The objective of the current research is to improve static/dynamics characteristics of hydrostatic bearings. Hydrostatic bearings always work in harsh environmental conditions that effect their performance, and which may even result in their failure. The current research proposes a mathematical model-based system for hydrostatic bearings that helps to improve its static/dynamic characteristics under varying conditions of performance-influencing variables such as temperature, spindle speed, external load, and clearance gap. To achieve these objectives, the capillary restrictors are replaced with servo valves, and a mathematical model is developed along with robust control design systems. The control system consists of feedforward and feedback control techniques that have not been applied before for hydrostatic bearings in the published literature. The feedforward control tries to remove a disturbance before it enters the system while feedback control achieves the objective of disturbance rejection and improves steady-state characteristics. The feedforward control is a trajectory-based controller and the feedback controller is a sliding mode controller with a PID sliding surface. The particle swarm optimization algorithm is used to tune the 6-dimensional vector of the tuning parameters with multi-objective performance criteria. Numerical investigations have been carried out to check the performance of the proposed system under varying conditions of viscosity, clearance gap, external load and the spindle speed. The comparison of our results with the published literature shows the effectiveness of the proposed system.

Alteration in myocardial oxygen balance during exercise after beta-adrenergic blockade in dogs

1980 ◽  
Vol 49 (1) ◽  
pp. 28-33 ◽  
Author(s):  
G. R. Heyndrickx ◽  
J. L. Pannier ◽  
P. Muylaert ◽  
C. Mabilde ◽  
I. Leusen
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Myocardial Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Sinus ◽  
Myocardial Oxygen Consumption ◽  
Left Ventricular ◽  
Adrenergic Blockade ◽  
Oxygen Balance

The effects of beta-adrenergic blockade upon myocardial blood flow and oxygen balance during exercise were evaluated in eight conscious dogs, instrumented for chronic measurements of coronary blood flow, left ventricular pressure, aortic blood pressure, heart rate, and sampling of arterial and coronary sinus venous blood. The administration of propranolol (1.5 mg/kg iv) produced a decrease in heart rate, peak left ventricular (LV) dP/dt, LV (dP/dt/P, and an increase in LV end-diastolic pressure during exercise. Mean coronary blood flow and myocardial oxygen consumption were lower after propranolol than at the same exercise intensity in control conditions. The oxygen delivery-to-oxygen consumption ratio and the coronary sinus oxygen content were also significantly lower. It is concluded that the relationship between myocardial oxygen supply and demand is modified during exercise after propranolol, so that a given level of myocardial oxygen consumption is achieved with a proportionally lower myocardial blood flow and a higher oxygen extraction.

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