Regulation of cardiac output during rapid volume loading

1979 ◽  
Vol 237 (3) ◽  
pp. R197-R202
Author(s):  
G. E. Barnes ◽  
B. C. Chevis ◽  
H. J. Granger
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Control Mechanism ◽  
Initial Conditions ◽  
Cardiac Response ◽  
Conscious Dogs ◽  
Volume Loading ◽  
Relative Contribution ◽  
Open Chest

Interactions between heart rate (HR) and the Frank-Starling mechanism in augmenting cardiac output (CO) during acute volume loading were studied in dogs under varying conditions. In normal conscious dogs with low HRs of 70--90 beats/min, end-diastolic diameter (EDD) was maximal and CO was increased reflexly by cardioacceleration. By contrast, anesthetized open-chest dogs with high HRs ranging from 140 to 160 beats/min, responded with bradycardia and CO was adjusted solely by increasing stroke volume (SV). In anesthetized open-chest dogs with low HRs, EDD was less than maximal and increases in both HR and SV contributed to augment CO. These data show that both the cardioacceleration reflex and the Frank-Starling mechanism are important determinants of the cardiac response to elevated preload. Although the relative contribution of each control mechanism varies with initial conditions, their interplay extends the range of cardioregulation beyond that attainable by either loop operating alone.

Cardiac Response During Trumpet Playing

2010 ◽  
Vol 25 (1) ◽  
pp. 16-21 ◽  
Author(s):  
Donald U Robertson ◽  
Lynda Federoff ◽  
Keith E Eisensmith
Keyword(s):  
College Students ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Response ◽  
Physiological Efficiency ◽  
Rest Periods ◽  
Upper Register

Heart rate, heart rate variability, stroke volume, and cardiac output were measured while six college students and six professionals played trumpet. One-minute rest periods were followed by 1 minute of playing exercises designed to assess the effects of pitch and articulation. Heart rate and heart rate variability increased during playing, but stroke volume decreased. Changes in heart rate between resting and playing were greater for students, although beat-to-beat variability was larger for professionals in the upper register. These results suggest that expertise is characterized by greater physiological efficiency.

Constancy of stroke volume in ventricular responses to exertion

1959 ◽  
Vol 196 (4) ◽  
pp. 745-750 ◽  
Author(s):  
Robert F. Rushmer
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Response ◽  
Indirect Measurements ◽  
Increase Stroke Volume ◽  
Normal Man ◽  
The Right ◽  
Response To Exercise ◽  
Indicator Dilution Techniques

Diastolic and systolic dimensions of the left ventricle and the free wall of the right ventricle in intact dogs are affected little by spontaneous exercise. The concept that stroke volume and heart rate in normal man increase by about the same relative amounts was derived from estimations of cardiac output, particularly in athletes, based upon indirect measurements using foreign gases or CO2. Data for man obtained with the modern cardiac catheterization or indicator dilution techniques confirm the impression derived from intact dogs that increased stroke volume is neither an essential nor a characteristic feature of the normal cardiac response to exercise. Stroke volume undoubtedly increases whenever cardiac output is increased with little change in heart rate (e.g. in athletes or in patients with chronic volume loads on the heart). Tachycardia produced experimentally with an artificial pacemaker in a resting dog causes a marked reduction in diastolic and systolic dimensions and in the stroke change of dimensions. The factors generally postulated to increase stroke volume during normal exercise may prevent the reduction in stroke volume accompanying tachycardia.

Minute-to-minute covariations in cardiovascular activity of conscious dogs

1979 ◽  
Vol 236 (3) ◽  
pp. H434-H439 ◽  
Author(s):  
D. E. Anderson ◽  
J. E. Yingling ◽  
K. Sagawa
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Peripheral Resistance ◽  
Aversive Stimulation ◽  
Conscious Dogs ◽  
Cardiovascular Activity ◽  
Independent Events ◽  
Constant Coefficient Of Variation ◽  
Cardiovascular Variables

Cardiovascular activity of chronically instrumented conscious dogs was monitored continuously during daily sessions of rest or of intermittent aversive stimulation. Data analysis of minute-to-minute averages revealed that cardiovascular variables changed in patterns, rather than as isolated independent events. Variations in cardiac output were highly positively correlated with concurrent variations in heart rate in all subjects under both conditions (mean r = +0.93). Variations in heart rate were two to five times as great as stroke volume, which was remarkably constant (coefficient of variation averaged only 4.6%). Variations in mean arterial pressure were consistently correlated with the variations in cardiac output (mean r = + 0.66) and heart rate (mean r = +0.68), but were poorly correlated with the small changes in stroke volume (mean r = -0.17) and total peripheral resistance (mean r = -0.16).

Effects of reserpine on circulation of the rat after microwave irradiation

1962 ◽  
Vol 202 (6) ◽  
pp. 1171-1174 ◽  
Author(s):  
Theodore Cooper ◽  
Teresa Pinakatt ◽  
Max Jellinek ◽  
Alfred W. Richardson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Continuous Wave ◽  
Peripheral Resistance ◽  
Thermal Response ◽  
Cardiac Response ◽  
Tissue Temperature ◽  
White Rats

Hyperthermia of 40.5 C was induced in anesthetized white rats by microwave exposure (2,450-Mc continuous wave, .08 w/cm2). Thermal response was accompanied by increased cardiac output, stroke volume, cardiac work, and heart rate. Blood pressure and total peripheral resistance decreased. Administration of reserpine as a single dose of 2.5 mg/kg body wt. 1 day before the experiment depleted the myocardial norepinephrine, but did not eliminate the accelerated heart rate and increase of cardiac output during hyperthermia. Hyperthermia after reserpine did not alter significantly the stroke volume and blood pressure, and the peripheral resistance decreased. These data suggest that the circulatory adaptation to microwave hyperthermia is mediated not only through the sympathetic nervous system, but by other mechanisms such as direct cardiac response to the increased tissue temperature.

Integrated cardiac and peripheral vascular response to atriopeptin 24 in conscious dogs

1986 ◽  
Vol 251 (6) ◽  
pp. H1292-H1297 ◽  
Author(s):  
J. T. Shapiro ◽  
V. M. DeLeonardis ◽  
P. Needleman ◽  
T. H. Hintze
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Blood Flows ◽  
Blood Flow Ratio ◽  
The Right

Little attention has been directed toward the action of atrial peptides on integrated cardiovascular function. In conscious dogs intravenous injection of atriopeptin 24 (10 micrograms/kg) reduced mean arterial pressure (11 +/- 3.2%), mean left atrial pressure (32 +/- 8.6%), left ventricular (LV) end-diastolic pressure (24 +/- 4.3%), and increased heart rate (25 +/- 6.2%). LV dP/dt and stroke volume increased 17 +/- 4.0 and 12 +/- 3.3%, respectively. Cardiac output increased 39 +/- 6.3%. These effects were only acute, lasting less than 10 min. The tachycardia and increase in LV dP/dt were abolished by combined beta-adrenergic and muscarinic cholinergic blocking agents. During an infusion of atriopeptin 24 (10 micrograms X kg-1 X min-1) blood flow, as measured with radioactive microspheres, increased to both the left (101 +/- 35%) and right kidney (122 +/- 37%) and to the spleen (140 +/- 50%). However, blood flow to the stomach, large and small intestine, pancreas, liver, and skeletal muscle did not change, indicating the selectivity of the atriopeptin. Blood flow in the right ventricle, septum, and in all layers of the left ventricle increased slightly, resulting in no change in the endocardial-to-epicardial blood flow ratio most likely due to the changes in myocardial function, i.e., heart rate and stroke volume. Thus, in conscious dogs, atriopeptins increase myocardial performance most likely indirectly secondary to baroreflex unloading after the direct hypotensive effects of atriopeptin 24. This serves to increase cardiac output at a time when renal and splenic blood flows are increased.

scholarly journals Evaluation of Stroke Volume Variation Obtained by the FloTrac™/Vigileo™ System to Guide Preoperative Fluid Therapy in Patients Undergoing Brain Surgery

2012 ◽  
Vol 40 (3) ◽  
pp. 1175-1181 ◽  
Author(s):  
J Li ◽  
Fh Ji ◽  
Jp Yang
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stroke Volume ◽  
Stroke Volume Variation ◽  
Brain Surgery ◽  
Fluid Loading ◽  
Volume Loading ◽  
Fluid Infusion ◽  
Volume Variation ◽  
Ringer’S Lactate

OBJECTIVE: The accuracy of stroke volume variation (SVV) obtained by the FloTrac™/Vigileo™ system in otherwise healthy patients undergoing brain surgery was assessed. METHODS: Anaesthesia was induced in 48 patients with minimal fluid infusion. Before surgery, fluid volume loading was performed by infusion with Ringer's lactate solution in 200 ml steps over 3 min, repeated successively if the patient responded with an increase in stroke volume of ≥ 10%, until the increase was < 10% (nonresponsive). RESULTS: A total of 157 volume loading steps were performed in the 48 patients. Responsive and nonresponsive steps differed significantly in baseline values of blood pressure, heart rate and SVV. Significant correlations were found between the change in stroke volume after fluid loading and values of blood pressure, heart rate and SVV before fluid loading, with SVV the most sensitive variable. CONCLUSION: Stroke volume variation obtained using the FloTrac™/Vigileo™ system is a sensitive predictor of fluid responsiveness in healthy patients before brain surgery.

Physiological factors associated with the lower maximal oxygen consumption of master runners

1989 ◽  
Vol 66 (2) ◽  
pp. 949-954 ◽  
Author(s):  
A. M. Rivera ◽  
A. E. Pels ◽  
S. P. Sady ◽  
M. A. Sady ◽  
E. M. Cullinane ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Maximal Oxygen Consumption ◽  
Maximal Heart Rate ◽  
Distance Runners ◽  
Physiological Factors ◽  
Factors Associated ◽  
Older Athletes ◽  
Maximal Cardiac Output

We examined the hemodynamic factors associated with the lower maximal O2 consumption (VO2max) in older formerly elite distance runners. Heart rate and VO2 were measured during submaximal and maximal treadmill exercise in 11 master [66 +/- 8 (SD) yr] and 11 young (32 +/- 5 yr) male runners. Cardiac output was determined using acetylene rebreathing at 30, 50, 70, and 85% VO2max. Maximal cardiac output was estimated using submaximal stroke volume and maximal heart rate. VO2max was 36% lower in master runners (45.0 +/- 6.9 vs. 70.4 +/- 8.0 ml.kg-1.min-1, P less than or equal to 0.05), because of both a lower maximal cardiac output (18.2 +/- 3.5 vs. 25.4 +/- 1.7 l.min-1) and arteriovenous O2 difference (16.6 +/- 1.6 vs. 18.7 +/- 1.4 ml O2.100 ml blood-1, P less than or equal to 0.05). Reduced maximal heart rate (154.4 +/- 17.4 vs. 185 +/- 5.8 beats.min-1) and stroke volume (117.1 +/- 16.1 vs. 137.2 +/- 8.7 ml.beat-1) contributed to the lower cardiac output in the older athletes (P less than or equal 0.05). These data indicate that VO2max is lower in master runners because of a diminished capacity to deliver and extract O2 during exercise.

The Role of the Aortic Body Chemoreceptors in the Cardiac and Respiratory Responses to Acute Hypoxia in the Anesthetized Dog

1973 ◽  
Vol 51 (4) ◽  
pp. 249-259 ◽  
Author(s):  
G. P. Biro ◽  
J. D. Hatcher ◽  
D. B. Jennings
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Acute Hypoxia ◽  
Control Period ◽  
Indirect Evidence ◽  
Minute Volume ◽  
Significant Rise ◽  
Cardiac Response ◽  
Cardiac Responses ◽  
Respiratory Parameters

The participation of the aortic chemoreceptors in the reflex cardiac responses to acute hypoxia is suggested only by the indirect evidence of pharmacological stimulation of these receptors. In order to assess their role more directly, the response to a 15 min period of hypoxia was determined after surgical denervation of the aortic chemoreceptors (A.D.), and compared with the response of sham-operated (S.O.) dogs, anesthetized with morphine–pentobarbital. In the control period, while breathing room air, the cardiovascular and respiratory parameters measured in the A.D. animals were not different from those of the S.O. dogs. Hypoxia (partial pressure of oxygen approximately 30 mm Hg) in the S.O. dogs was associated with a statistically significant rise in the heart rate (+71 ± 7 min−1, mean ± S.E.M.) and of the cardiac output (+25 ± 10 ml kg−1 min−1). In the A.D. animals, the significantly smaller increment in heart rate (+29 ± 6 min−1) was associated with a fall of the cardiac output (−16 ± 12 ml kg−1 min−1). The hypoxia-induced changes in heart rate and cardiac output in the S.O. animals were different (p < 0.05) from those in the A.D. group. The minute volume of ventilation was significantly augmented in both groups, and to a comparable extent. These findings indicate that the aortic chemoreceptors play a significant role in the cardiac response to hypoxia, but they do not affect, to a significant extent, the respiratory response.

Cardiovascular changes in the exercising emu

1983 ◽  
Vol 104 (1) ◽  
pp. 193-201 ◽  
Author(s):  
B. Grubb ◽  
D. D. Jorgensen ◽  
M. Conner
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Oxygen Content ◽  
Body Mass ◽  
Fold Increase ◽  
Exercise Heart Rate ◽  
Rate Of Oxygen Consumption ◽  
Cardiovascular Variables

Cardiovascular variables were studied as a function of oxygen consumption in the emu, a large, flightless ratite bird well suited to treadmill exercise. At the highest level of exercise, the birds' rate of oxygen consumption (VO2) was approximately 11.4 times the resting level (4.2 ml kg-1 min-1). Cardiac output was linearly related to VO2, increasing 9.5 ml for each 1 ml increase in oxygen consumption. The increase in cardiac output is similar to that in other birds, but appears to be larger than in mammals. The venous oxygen content dropped during exercise, thus increasing the arteriovenous oxygen content difference. At the highest levels of exercise, heart rate showed a 3.9-fold increase over the resting rate (45.8 beats min-1). The mean resting specific stroke volume was 1.5 ml per kg body mass, which is larger than shown by most mammals. However, birds have larger hearts relative to body mass than do mammals, and stroke volume expressed per gram of heart (0.18 ml g-1) is similar to that for mammals. Stroke volume showed a 1.8-fold increase as a result of exercise in the emus, but a change in heart rate plays a greater role in increasing cardiac output during exercise.

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