scholarly journals Total arterial compliance estimated from the time constant of aortic pressure decay: the influence of downstream pressure

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Denis Chemla ◽  
Alain Nitenberg
Keyword(s):  
Time Constant ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Pressure Decay ◽  
Total Arterial Compliance

Total arterial compliance estimated by stroke volume-to-aortic pulse pressure ratio in humans

1998 ◽  
Vol 274 (2) ◽  
pp. H500-H505 ◽  
Author(s):  
Denis Chemla ◽  
Jean-Louis Hébert ◽  
Catherine Coirault ◽  
Karen Zamani ◽  
Isabelle Suard ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Time Constant ◽  
Pulse Pressure ◽  
Arterial Compliance ◽  
Pressure Ratio ◽  
Aortic Pressure ◽  
Reliable Estimate ◽  
Pressure Decay ◽  
Total Arterial Compliance ◽  
Significant Difference

On the basis of the windkessel model, the stroke volume-to-aortic pulse pressure ratio (SV/PP) has been proposed as an estimate of total arterial compliance, but recent studies have questioned this approximation. Aortic pressure was obtained at rest in 31 adults undergoing cardiac catheterization (47 ± 14 yr): controls ( n = 7), patients with dilated cardiomyopathy ( n = 10), and patients with other cardiac diseases ( n = 14). We calculated PP, mean aortic pressure (MAoP), heart period ( T), SV (thermodilution cardiac output/heart rate), total peripheral resistance ( R), total arterial compliance estimated by area method ( Carea), and the time constant of aortic pressure decay in diastole ( RCarea). In the overall population ( n = 31), there was no significant difference between SV/PP and Carea. SV/PP was linearly related to Carea(SV/PP = 0.99 Carea+ 0.05; r = 0.98; P < 0.001); the slope and intercept did not differ from unity and zero, respectively. Similar results were obtained in the three subgroups. These results implied that PP/MAoP and T/ RCareawere proportionally related ( T/ RCarea= 1.18PP/MAoP − 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest 1) SV/PP gave a reliable estimate of Carea, and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAoP. This last relationship could be considered an aspect of the coupling between the left ventricle and its load.

Use of pulse pressure method for estimating total arterial compliance in vivo

1999 ◽  
Vol 276 (2) ◽  
pp. H424-H428 ◽  
Author(s):  
N. Stergiopulos ◽  
P. Segers ◽  
N. Westerhof
Keyword(s):  
Pulse Pressure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Lower Limbs ◽  
Pressure Method ◽  
Total Arterial Compliance ◽  
The Difference ◽  
Pulse Pressure Method

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.

Estimation of total arterial compliance: an improved method and evaluation of current methods

1986 ◽  
Vol 251 (3) ◽  
pp. H588-H600 ◽  
Author(s):  
Z. Liu ◽  
K. P. Brin ◽  
F. C. Yin
Keyword(s):  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Improved Methods ◽  
Mean Aortic Pressure

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.

Estimating arterial resistance and compliance during transient conditions in humans

1989 ◽  
Vol 257 (1) ◽  
pp. H190-H197 ◽  
Author(s):  
F. C. Yin ◽  
Z. R. Liu
Keyword(s):  
Pressure Difference ◽  
Arterial Compliance ◽  
Quantitative Difference ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Hemodynamic Parameters ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Highly Correlated ◽  
Almost All

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)

Apparent arterial compliance

1998 ◽  
Vol 274 (4) ◽  
pp. H1393-H1403 ◽  
Author(s):  
Christopher M. Quick ◽  
David S. Berger ◽  
Abraham Noordergraaf
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Arterial Compliance ◽  
Complex Function ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Lumped Model ◽  
Total Arterial Compliance

Recently, there has been renewed interest in estimating total arterial compliance. Because it cannot be measured directly, a lumped model is usually applied to derive compliance from aortic pressure and flow. The archetypical model, the classical two-element windkessel, assumes 1) system linearity and 2) infinite pulse wave velocity. To generalize this model, investigators have added more elements and have incorporated nonlinearities. A different approach is taken here. It is assumed that the arterial system 1) is linear and 2) has finite pulse wave velocity. In doing so, the windkessel is generalized by describing compliance as a complex function of frequency that relates input pressure to volume stored. By applying transmission theory, this relationship is shown to be a function of heart rate, peripheral resistance, and pulse wave reflection. Because this pressure-volume relationship is generally not equal to total arterial compliance, it is termed “apparent compliance.” This new concept forms the natural counterpart to the established concept of apparent pulse wave velocity.

Estimation of total systemic arterial compliance in humans

1990 ◽  
Vol 69 (1) ◽  
pp. 112-119 ◽  
Author(s):  
W. K. Laskey ◽  
H. G. Parker ◽  
V. A. Ferrari ◽  
W. G. Kussmaul ◽  
A. Noordergraaf
Keyword(s):  
Heart Failure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Idiopathic Dilated Cardiomyopathy ◽  
Windkessel Model ◽  
Failure Group ◽  
Control Subjects ◽  
Total Arterial Compliance

Systemic arterial compliance, a major component of aortic input impedance, was determined in 10 patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy and 11 age-matched control subjects found free of detectable cardiovascular disease. Total arterial compliance was determined from high-fidelity ascending aortic pressure and velocity recordings using 1) the traditional monoexponential aortic diastolic pressure decay and 2) the direct solution of the equation, which describes the three-element windkessel model of the arterial system. Resting values for total arterial compliance (x10(-3) cm5/dyn) derived from method 1 were significantly correlated with compliance derived from method 2 (r = 0.89, P less than 0.01). However, method 1 values (control mean 1.15 +/- 0.27, heart failure mean 1.18 +/- 0.54) were consistently and significantly lower (P less than 0.001) than method 2 values (control mean 1.59 +/- 0.50, heart failure mean 1.38 +/- 0.60). Resting total arterial compliance in heart-failure patients was not significantly different from control subjects. Total arterial compliance did not significantly change with exercise in either group despite increases in arterial pressure. However, nitroprusside administration in the heart-failure group increased total arterial compliance both at rest and on exercise compared with the unmedicated state. These different methodological approaches to the estimation of total arterial compliance in humans resulted in significantly different absolute values for compliance, although both methods provided concordant results with respect to the response of arterial compliance to physiological and pharmacological interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Beat-to-beat estimation of peripheral resistance and arterial compliance during pressure transients

1987 ◽  
Vol 252 (6) ◽  
pp. H1275-H1283 ◽  
Author(s):  
G. P. Toorop ◽  
N. Westerhof ◽  
G. Elzinga
Keyword(s):  
Heart Rate ◽  
Arterial Compliance ◽  
Peripheral Resistance ◽  
Estimation Method ◽  
Aortic Pressure ◽  
Autonomous Nervous System ◽  
Mean Flow ◽  
Arterial Tree ◽  
Total Arterial Compliance

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.

Contribution of systemic vascular resistance and total arterial compliance to effective arterial elastance in humans

2003 ◽  
Vol 285 (2) ◽  
pp. H614-H620 ◽  
Author(s):  
Denis Chemla ◽  
Isabelle Antony ◽  
Yves Lecarpentier ◽  
Alain Nitenberg
Keyword(s):  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Left Ventricular ◽  
Reliable Estimate ◽  
Arterial Elastance ◽  
Total Arterial Compliance ◽  
Arterial Load ◽  
Effective Arterial Elastance

The respective contribution of systemic vascular resistance ( R) and total arterial compliance ( C) to the arterial load remains to be established in humans. Effective arterial elastance ( Ea), i.e., the left ventricular end-systolic pressure (LVESP)-over-stroke volume ratio, is a reliable estimate of arterial load. It is widely accepted that Ea mainly relates to mean aortic pressure (MAP) and thus to the R-to- T ratio ( R/ T ratio), where T is cycle length. We tested the contribution of R/ T and 1/ C to Ea in 20 normotensive and 46 hypertensive subjects (MAP range: 84–160 mmHg). The multilinear model applied ( Ea = 1.00 R/ T + 0.42/ C – 0.04; r2 = 0.97). The sensitivity of Ea to a change in R/ T was 2.5 times higher than to a similar change in 1/ C in both normotensive and hypertensive adults. The LVESP was more strongly related to systolic aortic pressure (SAP; r2 = 0.94) than to MAP ( r2 = 0.83), and LVESP matched 90% SAP (bias = 0 ± 5mmHg). An alternative model of Ea is proposed, in which Ea is proportional to the heart rate × SAP product-over-cardiac index ratio whatever the MAP.

scholarly journals Decreased time constant of the pulmonary circulation in chronic thromboembolic pulmonary hypertension

2013 ◽  
Vol 305 (2) ◽  
pp. H259-H264 ◽  
Author(s):  
Robert V. MacKenzie Ross ◽  
Mark R. Toshner ◽  
Elaine Soon ◽  
Robert Naeije ◽  
Joanna Pepke-Zaba
Keyword(s):  
Pulmonary Hypertension ◽  
Time Constant ◽  
Pulmonary Circulation ◽  
Wave Reflection ◽  
Arterial Compliance ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Left Heart Failure ◽  
Thromboembolic Pulmonary Hypertension ◽  
Pulmonary Arterial ◽  
Rc Time Constant

This study analyzed the relationship between pulmonary vascular resistance (PVR) and pulmonary arterial compliance ( Ca) in patients with idiopathic pulmonary arterial hypertension (IPAH) and proximal chronic thromboembolic pulmonary hypertension (CTEPH). It has recently been shown that the time constant of the pulmonary circulation (RC time constant), or PVR × Ca, remains unaltered in various forms and severities of pulmonary hypertension, with the exception of left heart failure. We reasoned that increased wave reflection in proximal CTEPH would be another cause of the decreased RC time constant. We conducted a retrospective analysis of invasive pulmonary hemodynamic measurements in IPAH ( n = 78), proximal CTEPH ( n = 91) before (pre) and after (post) pulmonary endarterectomy (PEA), and distal CTEPH ( n = 53). Proximal CTEPH was defined by a postoperative mean pulmonary artery pressure (PAP) of ≤25 mmHg. Outcome measures were the RC time constant, PVR, Ca, and relationship between systolic and mean PAPs. The RC time constant for pre-PEA CTEPH was 0.49 ± 0.11 s compared with post-PEA-CTEPH (0.37 ± 0.11 s, P < 0.0001), IPAH (0.63 ± 0.14 s, P < 0.001), and distal CTEPH (0.55 ± 0.12 s, P < 0.05). A shorter RC time constant was associated with a disproportionate decrease in systolic PAP with respect to mean PAP. We concluded that the pulmonary RC time constant is decreased in proximal CTEPH compared with IPAH, pre- and post-PEA, which may be explained by increased wave reflection but also, importantly, by persistent structural changes after the removal of proximal obstructions. A reduced RC time constant in CTEPH is in accord with a wider pulse pressure and hence greater right ventricular work for a given mean PAP.

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