scholarly journals Acute Tachycardia Increases Aortic Distensibility, but Reduces Total Arterial Compliance Up to a Moderate Heart Rate

2018 ◽  
Vol 9 ◽  
Author(s):  
Yunlong Huo ◽  
Huan Chen ◽  
Ghassan S. Kassab
1987 ◽  
Vol 252 (6) ◽  
pp. H1275-H1283 ◽  
Author(s):  
G. P. Toorop ◽  
N. Westerhof ◽  
G. Elzinga

We have used a computer-based parameter estimation method to obtain peripheral resistance, total arterial compliance, and characteristic resistance from the measurement of aortic pressure and flow in the open-thorax cat, assuming the three-element windkessel as a model of the systemic arterial tree. The method can be applied on a beat-to-beat basis in the steady state and in transients. We have validated this method by analyzing nonsteady-state data obtained from an electrical analog with fixed values of the resistances and compliance and by showing that the values obtained by this procedure were within 5% of the fixed values of the circuit. Changes in total peripheral resistance and arterial compliance were studied before, during, and after acute heart rate changes in five open-thorax cats with blocked autonomous nervous system. As expected, the peripheral resistance, estimated during the heart rate transient [3.93 +/- 0.94 (SE) kPa X ml-1 X s] was the same as before the transient (3.53 +/- 0.83 kPa X ml-1 X s); total arterial compliances were also identical (0.28 +/- 0.04 vs. 0.27 +/- 0.03 ml/kPa). In six cats without nervous blockade we obtained similar results. Calculation of peripheral resistance during transients from the mean pressure-to-mean flow ratio, i.e., without correction for arterial compliance, suggested changes in resistance values of less than or equal to 57%, which shows that correction is necessary. The findings indicate that peripheral resistance and total arterial compliance can be estimated in vivo on a beat-to-beat basis, even during hemodynamic transients.


1999 ◽  
Vol 276 (2) ◽  
pp. H424-H428 ◽  
Author(s):  
N. Stergiopulos ◽  
P. Segers ◽  
N. Westerhof

We determined total arterial compliance from pressure and flow in the ascending aorta of seven anesthetized dogs using the pulse pressure method (PPM) and the decay time method (DTM). Compliance was determined under control and during occlusion of the aorta at four different locations (iliac, renal, diaphragm, and proximal descending thoracic aorta). Compliance of PPM gave consistently lower values (0.893 ± 0.015) compared with the compliance of DTM (means ± SE; r = 0.989). The lower compliance estimates by the PPM can be attributed to the difference in mean pressures at which compliance is determined (mean pressure, 81.0 ± 3.6 mmHg; mean diastolic pressure, over which the DTM applies, 67.0 ± 3.6 mmHg). Total arterial compliance under control conditions was 0.169 ± 0.007 ml/mmHg. Compliance of the proximal aorta, obtained during occlusion of the proximal descending aorta, was 0.100 ± 0.007 ml/mmHg. Mean aortic pressure was 80.4 ± 3.6 mmHg during control and 102 ± 7.7 mmHg during proximal descending aortic occlusion. From these results and assuming that upper limbs and the head contribute as little as the lower limbs, we conclude that 60% of total arterial compliance resides in the proximal aorta. When we take into account the inverse relationship between pressure and compliance, the contribution of the proximal aorta to the total arterial compliance is even more significant.


2018 ◽  
Vol 25 (14) ◽  
pp. 1496-1497
Author(s):  
Theodore G Papaioannou ◽  
Manolis Vavuranakis ◽  
Dimitris Tousoulis

2003 ◽  
Vol 88 (11) ◽  
pp. 5375-5380 ◽  
Author(s):  
Anna A. Ahimastos ◽  
Melissa Formosa ◽  
Anthony M. Dart ◽  
Bronwyn A. Kingwell

Abstract Age-related large artery stiffening is more pronounced in women compared with men and is an important cause of isolated systolic hypertension. This study aimed to investigate whether such gender differences are inherent or the result of sex steroid influences. Healthy children prepuberty [26 female (10.3 ± 0.1 yr), 32 male (10.3 ± 0.1 yr), mean age ± sd] and post puberty [30 female (15.9 ± 0.2 yr), 22 male (15.9 ± 0.4 yr)] were studied. Large artery stiffness was assessed globally via systemic arterial compliance and regionally via pulse wave velocity. Prepubertal males and females did not differ in body size, cardiac output, or heart rate. Prepubertal females had stiffer large arteries and higher pulse pressure than age-matched males (P < 0.05). Postpubertal males were taller and heavier and had a greater cardiac output and lower heart rate compared with similarly aged females. In relation to pubertal status, females developed more distensible large arteries post puberty whereas males developed stiffer large vessels (P < 0.05). These changes where such that central large artery stiffness was similar between genders in the postpubertal group. Together these data suggest that large artery stiffness varies intrinsically between genders but is also modulated by both male and female sex steroids.


1987 ◽  
Vol 253 (1) ◽  
pp. H126-H132
Author(s):  
R. W. Lee ◽  
L. D. Lancaster ◽  
D. Buckley ◽  
S. Goldman

To determine whether changes in the venous circulation were responsible for preload-afterload mismatch with angiotensin, we examined the changes in the heart and the peripheral circulation in six splenectomized dogs after ganglion blockade during an angiotensin infusion to increase mean aortic pressure 25 and then 50%. The peripheral circulation was evaluated by measuring mean circulatory filling pressure (MCFP), arterial compliance, and venous compliance. A 25% increase in mean aortic pressure increased MCFP from 6.2 +/- 0.3 to 7.6 +/- 0.3 mmHg (P less than 0.001) but did not change cardiac output, heart rate, or stroke volume. Systemic vascular resistance increased (P less than 0.01) from 0.50 +/- 0.02 to 0.59 +/- 0.03 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.03 to 0.06 +/- 0.03 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.6 +/- 0.1 ml X mmHg-1 X kg-1, respectively. A 50% elevation in mean aortic pressure increased MCFP from 7.1 +/- 0.4 to 9.5 +/- 0.9 mmHg (P less than 0.001) but did not change heart rate. At this level of aortic pressure, cardiac output and stroke volume decreased (P less than 0.01) 12 and 19%, respectively, whereas systemic vascular resistance increased (P less than 0.001) from 0.48 +/- 0.03 to 0.83 +/- 0.05 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.01 to 0.05 +/- 0.01 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.4 +/- 0.1 ml X mmHg-1 X kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


1986 ◽  
Vol 251 (3) ◽  
pp. H588-H600 ◽  
Author(s):  
Z. Liu ◽  
K. P. Brin ◽  
F. C. Yin

Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that compliance is constant, i.e., that arterial pressure-volume (P-V) relations are linear, and they also assume that diastolic aortic pressure decay is an exponential function of time. Both of these assumptions, however, are questionable. This study proposes improved methods of estimating compliance based on a Windkessel model of the arterial system but which utilize the area under the pressure tracing rather than the waveform itself. Formulations accounting for both linear and three hypothetical nonlinear arterial P-V relations (exponential, logarithmic, and parabolic) are presented. Data from patients with congestive heart failure and hypertension are used for illustration. Compliances assuming linear P-V relations are reasonably close to those assuming nonlinear P-V relations only at mean aortic pressure. At end-diastolic pressure the linear assumption underestimates and at peak systolic it overestimates the compliances obtained assuming nonlinear P-V relations. The simpler linear assumption still allows a first approximation to compliance, but we show that existing methods for obtaining compliance under this assumption have severe theoretical as well as practical shortcomings. Our proposed method avoids these shortcomings primarily because deviations from an exact exponential form of the pressure wave have less influence on these compliance estimates than currently used methods.


1989 ◽  
Vol 257 (1) ◽  
pp. H190-H197 ◽  
Author(s):  
F. C. Yin ◽  
Z. R. Liu

Almost all existing methods for estimating hemodynamic parameters are valid only during steady-state conditions. There is often a need, however, for estimating peripheral resistance and total arterial compliance during beat-to-beat transients such as during atrial fibrillation. During such transients the pressure at the onset and end of a cardiac cycle usually differ. This pressure difference necessitates a modification of usual methods used for estimating these hemodynamic parameters. In this paper we formulate a method for estimating resistance and total arterial compliance during such beat-to-beat transients. For simplicity the expressions are derived for a two-element windkessel model of the circulation. The method is a generalization of one we previously proposed. Rather than using parameter estimation techniques or having to assume a monoexponential pressure decay during diastole, our method uses the areas under the systolic and diastolic portions of the aortic pressure versus time tracing to obtain explicit expressions for compliance; both for the case where it is constant and when it is assumed to be nonlinear (exponential) function of pressure. Aortic pressure and flow data from patients undergoing cardiac catheterization are employed to illustrate the method. Results illustrate the quantitative difference between uncorrected and corrected estimates of both resistance and compliance as a function of the pressure difference between the onset and end of each beat. The uncorrected parameters were found to be linearly and highly correlated with these pressure differences. Regressions of pressure difference against normalized values revealed that the pooled data for all patients defined a single relationship.(ABSTRACT TRUNCATED AT 250 WORDS)


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