A Model for the Relationship Between the Arterial Pressure and the Heart Period

1989 ◽  
Vol 111 (4) ◽  
pp. 336-341
Author(s):  
F. Iacovelli ◽  
M. Napolitano ◽  
A. Federici ◽  
G. Sorrentino
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood ◽  
Average Blood Pressure ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Heart Cycle ◽  
Physiological Values ◽  
Experimental Values ◽  
The Relationship

This paper provides a simple model for predicting the relationship between steadystate heart rate and arterial blood pressure. Two current state-of-the-art models of the cardiovascular system as a pump operating in its circuit are reformulated and combined in order to highlight the role of the duration of the heart cycle. The proposed model establishes that the cardiac cycle lengthens linearly with the inverse of the average blood pressure. Experimental data are reported for sixteen preoperated conscious dogs resting quietly on their sides. Vagal and sympathetic blocks have been produced in four dogs in order to obtain a wide range of sympathetic and parasympathetic tones, namely, to cover the entire range of physiological values of the heart rate. For these dogs a comparison between the experimental values and the theoretical predictions shows a good agreement, the results of the linear regression model being statistically significant at the p = 0.001 level for three dogs and at the p = 0.01 level for the fourth dog.

Baroreflex modulation of sympathetic nerve activity to muscle in heat-stressed humans

2002 ◽  
Vol 282 (1) ◽  
pp. R252-R258 ◽  
Author(s):  
Jian Cui ◽  
Thad E. Wilson ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Whole Body ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Arterial Blood ◽  
The Relationship

To identify whether whole body heating alters arterial baroreflex control of muscle sympathetic nerve activity (MSNA), MSNA and beat-by-beat arterial blood pressure were recorded in seven healthy subjects during acute hypotensive and hypertensive stimuli in both normothermic and heat stress conditions. Whole body heating significantly increased sublingual temperature ( P < 0.01), MSNA ( P < 0.01), heart rate ( P< 0.01), and skin blood flow ( P < 0.001), whereas mean arterial blood pressure did not change significantly ( P > 0.05). During both normothermic and heat stress conditions, MSNA increased and then decreased significantly when blood pressure was lowered and then raised via intravenous bolus infusions of sodium nitroprusside and phenylephrine HCl, respectively. The slope of the relationship between MSNA and diastolic blood pressure during heat stress (−128.3 ± 13.9 U · beats−1 · mmHg−1) was similar ( P = 0.31) with normothermia (−140.6 ± 21.1 U · beats−1 · mmHg−1). Moreover, no significant change in the slope of the relationship between heart rate and systolic blood pressure was observed. These data suggest that arterial baroreflex modulation of MSNA and heart rate are not altered by whole body heating, with the exception of an upward shift of these baroreflex curves to accommodate changes in these variables that occur with whole body heating.

Baroreflex modulation of muscle sympathetic nerve activity during posthandgrip muscle ischemia in humans

2001 ◽  
Vol 91 (4) ◽  
pp. 1679-1686 ◽  
Author(s):  
Jian Cui ◽  
Thad E. Wilson ◽  
Manabu Shibasaki ◽  
Nicole A. Hodges ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Isometric Handgrip ◽  
Nerve Activity ◽  
Arterial Blood ◽  
Muscle Ischemia ◽  
The Relationship

To identify whether muscle metaboreceptor stimulation alters baroreflex control of muscle sympathetic nerve activity (MSNA), MSNA, beat-by-beat arterial blood pressure (Finapres), and electrocardiogram were recorded in 11 healthy subjects in the supine position. Subjects performed 2 min of isometric handgrip exercise at 40% of maximal voluntary contraction followed by 2.5 min of posthandgrip muscle ischemia. During muscle ischemia, blood pressure was lowered and then raised by intravenous bolus infusions of sodium nitroprusside and phenylephrine HCl, respectively. The slope of the relationship between MSNA and diastolic blood pressure was more negative ( P < 0.001) during posthandgrip muscle ischemia (−201.9 ± 20.4 units · beat−1 · mmHg−1) when compared with control conditions (−142.7 ± 17.3 units · beat−1 · mmHg−1). No significant change in the slope of the relationship between heart rate and systolic blood pressure was observed. However, both curves shifted during postexercise ischemia to accommodate the elevation in blood pressure and MSNA that occurs with this condition. These data suggest that the sensitivity of baroreflex modulation of MSNA is elevated by muscle metaboreceptor stimulation, whereas the sensitivity of baroreflex of modulate heart rate is unchanged during posthandgrip muscle ischemia.

Phenylephrine-induced elevations in arterial blood pressure are attenuated in heat-stressed humans

2002 ◽  
Vol 283 (5) ◽  
pp. R1221-R1226 ◽  
Author(s):  
Jian Cui ◽  
Thad E. Wilson ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Arterial Blood Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Peripheral Resistance ◽  
Whole Body ◽  
Baroreflex Control ◽  
Arterial Blood ◽  
The Relationship

To test the hypothesis that phenylephrine-induced elevations in blood pressure are attenuated in heat-stressed humans, blood pressure was elevated via steady-state infusion of three doses of phenylephrine HCl in 10 healthy subjects in both normothermic and heat stress conditions. Whole body heating significantly increased sublingual temperature by ∼0.5°C, muscle sympathetic nerve activity (MSNA), heart rate, and cardiac output and decreased total peripheral vascular resistance (TPR; all P < 0.005) but did not change mean arterial blood pressure (MAP; P > 0.05). At the highest dose of phenylephrine, the increase in MAP and TPR from predrug baselines was significantly attenuated during the heat stress [ΔMAP 8.4 ± 1.2 mmHg; ΔTPR 0.96 ± 0.85 peripheral resistance units (PRU)] compared with normothermia (ΔMAP 15.4 ± 1.4 mmHg, ΔTPR 7.13 ± 1.18 PRU; all P < 0.001). The sensitivity of baroreflex control of MSNA and heart rate, expressed as the slope of the relationship between MSNA and diastolic blood pressure, as well as the slope of the relationship between heart rate and systolic blood pressure, respectively, was similar between thermal conditions (each P > 0.05). These data suggest that phenylephrine-induced elevations in MAP are attenuated in heat-stressed humans without affecting baroreflex control of MSNA or heart rate.

Responses of ACTH, epinephrine, norepinephrine, and cardiovascular system to hemorrhage

1986 ◽  
Vol 251 (3) ◽  
pp. H612-H618 ◽  
Author(s):  
D. N. Darlington ◽  
J. Shinsako ◽  
M. F. Dallman
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Random Order ◽  
Plasma Acth ◽  
Arterial Blood ◽  
The Relationship ◽  
Subsequent Rise

Hemorrhages of various magnitudes were performed on conscious rats, and arterial pressure, heart rate, and plasma levels of adrenocorticotropin hormone (ACTH), epinephrine, and norepinephrine were measured. Eight rats were prepared with chronic femoral arterial cannulas and received a 10, 15, or 20 ml/kg X 3 min hemorrhage in random order on day 4, 7, or 10 after surgery. Mean arterial blood pressure, heart rate, and plasma ACTH, epinephrine, and norepinephrine concentrations were determined before and 20 min after hemorrhage. Arterial blood pressure decreased significantly immediately after each hemorrhage and slowly recovered over the next 20 min. Heart rate did not change during the 10 ml/kg X 3 min hemorrhage but decreased significantly after 15 and 20 ml/kg X 3 min hemorrhages. Plasma ACTH and epinephrine levels increased significantly 20 min after the 15 and 20 ml/kg X 3 min hemorrhages but not after 10 ml/kg X 3 min hemorrhage. Norepinephrine increased significantly 20 min after the 20 ml/kg X 3 min hemorrhage but not after the 10 or 15 ml/kg X 3 min hemorrhage. There was no significant effect of time and repeated hemorrhages on resting levels of plasma ACTH, epinephrine, norepinephrine, osmolality, or proteins. Since hemorrhage leads to a fall in arterial pressure and a subsequent rise in plasma ACTH, the relationship between plasma ACTH and mean arterial blood pressure during hemorrhage was examined in both conscious and acutely prepared pentobarbital sodium-anesthetized rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for altered α-adrenoreceptor responsiveness after a single bout of maximal exercise

2003 ◽  
Vol 95 (1) ◽  
pp. 192-198 ◽  
Author(s):  
Victor A. Convertino
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Vascular Resistance ◽  
Maximal Exercise ◽  
Peripheral Resistance ◽  
Experimental Conditions ◽  
Arterial Blood ◽  
Single Bout ◽  
Β Receptor ◽  
The Relationship

We studied hemodynamic responses to α- and β-receptor agonists in eight men to test the hypothesis that adrenoreceptor responsiveness is altered within 24 h of the performance of maximal exercise. Adrenoreceptor responsiveness was tested under two experimental conditions (with and without maximal exercise). Adrenoreceptor tests were performed 24 h after each subject performed graded upright cycle ergometry to volitional exhaustion. The 2 test days (experimental conditions) were separated by at least 1 wk, and the order of exercise and no-exercise conditions was counterbalanced. Steady-state graded infusions of phenylephrine (PE) and isoproterenol (Iso) were used to assess α- and β-adrenoreceptor responsiveness, respectively. Slopes calculated from linear regressions between Iso and PE doses and changes in heart rate, blood pressure, and leg vascular resistance for each subject were used as an index of α- and β-adrenoreceptor responsiveness. The slope of the relationship between heart rate and Iso with maximal exercise was 1,773 ± 164 beats · μg–1 · kg–1 · min–1 compared with 1,987 ± 142 beats · μg–1 · kg–1 · min–1 without exercise ( P = 0.158), whereas the slopes of the relationship between vascular resistance to Iso were -438 ± 123 peripheral resistance units (PRU) · μg–1 · kg–1 · min–1 with maximal exercise and -429 ± 105 ·μg–1·kg–1·min–1 without exercise ( P = 0.904). Maximal exercise was associated with greater ( P < 0.05) vascular resistance (15.1 ± 2.8 PRU·μg–1·kg–1· min–1) and mean arterial blood pressure (15.8 ± 2.1 mmHg · μg–1 · kg–1 · min–1) responses to PE infusion compared with no exercise (9.0 ± 2.0 PRU · μg–1 · kg–1 · min–1 and 10.9 ± 2.0 mmHg · μg–1 · kg–1 · min–1, respectively). These results provide evidence that a single bout of maximal exercise increases α1-adrenoreceptor responsiveness within 24 h without affecting β-cardiac and vascular adrenoreceptor responses.

The association between arterial properties and blood pressure in children

2015 ◽  
Vol 40 (1) ◽  
pp. 72-78 ◽  
Author(s):  
Aaron A. Phillips ◽  
Daniele Chirico ◽  
Nicole S. Coverdale ◽  
Laura K. Fitzgibbon ◽  
J. Kevin Shoemaker ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pulse Wave ◽  
Disease Risk ◽  
Pediatric Population ◽  
Cardiovascular Disease Risk ◽  
Intima Media Thickness ◽  
Healthy Children ◽  
Wide Range ◽  
The Relationship

Elevated blood pressure (BP) in adults is associated with increased arterial stiffness and thickness; however, its effect on arterial health in a pediatric population is less understood. The purpose of this study was to identify the relationship between childhood BP and arterial markers of arteriosclerotic progression. The study consisted of 106 children across a wide range of BP values divided into 2 BP groups: high BP (HBP; ≥95th percentile; n = 21) and normal BP (NBP; <90th percentile; n = 85) based on consistent automated BP measures taken at 2 time points. The laboratory examination involved systemic pulse wave velocity (PWV), common carotid artery (CCA) intima media thickness (IMT) and distensibility, as well as body mass index (BMI) and pubertal maturation. BMI and heart rate, as well as PWV (HBP: n = 15 and NBP: n = 56), were higher in the HBP group (p < 0.001) with no difference between groups for both CCA distensibility and IMT (HBP: n = 21 and NBP: n = 83). Multivariate linear regression revealed that BP group (p = 0.003) was an independent predictor of PWV after controlling for age, sex, BMI, heart rate, and maturation. Our findings demonstrate a higher systemic PWV with no difference in CCA IMT or distensibility in children with elevated BP. Hence, markers of cardiovascular disease risk are augmented in healthy children with elevated BP.

Bifurcation in a Simple Model of the Cardiovascular System

2000 ◽  
Vol 39 (02) ◽  
pp. 118-121 ◽  
Author(s):  
S. Akselrod ◽  
S. Eyal
Keyword(s):  
Nonlinear Dynamics ◽  
Blood Pressure ◽  
Heart Rate ◽  
Fixed Point ◽  
Cardiovascular System ◽  
Modified Model ◽  
Mayer Waves ◽  
Sustained Oscillations ◽  
Human Cardiovascular System ◽  
Physiological Values

Abstract:A simple nonlinear beat-to-beat model of the human cardiovascular system has been studied. The model, introduced by DeBoer et al. was a simplified linearized version. We present a modified model which allows to investigate the nonlinear dynamics of the cardiovascular system. We found that an increase in the -sympathetic gain, via a Hopf bifurcation, leads to sustained oscillations both in heart rate and blood pressure variables at about 0.1 Hz (Mayer waves). Similar oscillations were observed when increasing the -sympathetic gain or decreasing the vagal gain. Further changes of the gains, even beyond reasonable physiological values, did not reveal another bifurcation. The dynamics observed were thus either fixed point or limit cycle. Introducing respiration into the model showed entrainment between the respiration frequency and the Mayer waves.

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