Time-domain representation of ventricular-arterial  coupling as a windkessel and wave system

Wang, Jiun‐Jr; O’Brien, Aoife; Shrive, Nigel G.; Parker, Kim H.; Tyberg, John V.

doi:10.1152/ajpheart.00175.2002

Cited by 262 publications

(348 citation statements)

References 36 publications

(58 reference statements)

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“…This leads to the concept of reflected (backward-going) waves that can reinforce a forward-moving pressure wave (13)(14)(15). Recent elegant work by Wang et al (16) has suggested an alternative hypothesis. The arterial system can be thought of as a Windkessel type reservoir in which the level is controlled by peripheral resistance.…”

Section: Arterial Stiffnessmentioning

confidence: 99%

“…The arterial system can be thought of as a Windkessel type reservoir in which the level is controlled by peripheral resistance. A second component is very closely related to forward-travelling flow waves as a result of ventricular ejection (16). Aortic pressure is then the instantaneous summation of the reservoir pressure and the effects of the flow wave.…”

Section: Arterial Stiffnessmentioning

confidence: 99%

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Arterial stiffness or endothelial dysfunction as a surrogate marker of vascular risk

Anderson

2006

Canadian Journal of Cardiology

148

112

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T he understanding of the pathophysiology of atherosclerosis and its vascular complications has increased dramatically over the past decade. Numerous measurable biomarkers play a role in the atherosclerosis process, and are associated with clinically important vascular events. Not only has their evaluation advanced our knowledge of the atherosclerotic process but it has also accelerated a search for new diagnostic tools to aid in risk stratification. Putative factors include soluble biomarkers and imaging assessments of vascular structure and function. The endothelium plays a key role in vascular homeostasis through the release of a variety of paracrine factors that interact with platelets, inflammatory cells and the vessel wall. The endothelium's central location allows it to sense and respond to a variety of perturbations. Endothelial dysfunction is an early marker of disease. Risk factors can also affect mechanical properties such as arterial stiffness, which is now recognized as a major contributor to systolic hypertension in elderly people. Methods of assessing endothelial function and arterial stiffness are available for clinical research and recent evidence suggests that these measures may provide important prognostic information. ATTRIBUTES OF A SURROGATE BIOMARKEREpidemiological studies, such as Framingham, have allowed longitudinal assessment of cardiovascular events and the development of simple scoring tables for risk calculation (1,2). These factors involved include blood pressure, lipid profile, smoking status and age. More recently, many factors thought to be associated with the atherosclerotic process have been studied. Some of these have been shown to correlate with clinical outcomes and have been deemed biomarkers (3,4). However, association does not necessarily imply causation and, due to a variety of limitations, most of these markers will not be useful for the clinical evaluation of risk or drug therapy (5). To become clinically important, a biomarker must fulfill the criteria for a surrogate marker. A surrogate substitutes for clinically important end points with respect to how an individual feels, functions or survives. Classic examples include blood pressure and low density lipoprotein cholesterol. These are targets of treatment. A surrogate should meet the following criteria:• Adds independent information above currently used criteria;• Is reliably and reproducibly measured;• Accounts for a significant proportion of disease risk;• Provides good predictive value;• Is reasonably associated with the underlying pathophysiology;• If it is to be used in risk prevention, is present before the clinical appearance of the outcome; and• Is available and practical for widespread application (5-8). ADVANCES IN VASCULAR BIOLOGY

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Section: Arterial Stiffnessmentioning

confidence: 99%

Section: Arterial Stiffnessmentioning

confidence: 99%

Arterial stiffness or endothelial dysfunction as a surrogate marker of vascular risk

Anderson

2006

Canadian Journal of Cardiology

148

112

View full text Add to dashboard Cite

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“…The values of resistive components were by-products of the calculations of the P A-Res and PV-Res. The methods of calculation were detailed elsewhere (21,22). In brief, the arterial asymptotic pressure, P A-ϱ, is initially determined by fitting PAo during the later part of diastole by using a three-parameter exponential-decay equation.…”

Section: Theorymentioning

confidence: 99%

“…Viewed in the time domain, the arterial reservoir is a hydraulic integrator; the reservoir is charged when inflow exceeds outflow (during systole) and vice versa during diastole (22). The measured central aortic pressure (P Ao ) is equal to the sum of the P A-Res and the pressure due to arterial wave motion (wave pressure; P A-Wave ).…”

mentioning

confidence: 99%

Effects of vasoconstriction and vasodilatation on LV and segmental circulatory energetics

Wang

Shrive²,

Parker³

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

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Wang J-J, Shrive NG, Parker KH, Tyberg JV. Effects of vasoconstriction and vasodilatation on LV and segmental circulatory energetics. Am J Physiol Heart Circ Physiol 294: H1216-H1225, 2008. First published January 4, 2008 doi:10.1152/ajpheart.00983.2007.-Although the hydraulic work generated by the left ventricle (LV) is not disputed, how the work was dissipated through the systemic circulation is still subject to interpretation. Recently, we proposed that the systemic circulation should be considered as waves and a reservoir system (Wk). By combining the arterial and venous reservoirs, the systemic vascular resistance can be viewed as a series of resistors, which in sequence are the large-artery resistance, arterial reservoir resistance, the microcirculatory resistance, venous reservoir resistance, and large-vein resistance, and propelling blood through these resistance elements represents resistive losses. We then studied the changes in the fraction of the work consumed by each element when infusing methoxamine (MTX), a vasoconstrictor, and sodium nitroprusside (NP), a vasodilator. Results show that, under control condition, ϳ50% of the LV stroke work was dissipated through arterial reservoir resistance (NP, ϳ36%; MTX, ϳ27%), another ϳ25% was dissipated by the microcirculation (NP, ϳ20%; MTX, ϳ66%), and ϳ20% of work by the large-artery resistances (NP, ϳ37%; MTX, ϳ6%). The energy dissipated by the venous resistances was small and had limited variation with NP and MTX, where the large-vein and venous reservoir resistances shared ϳ1 and ϳ3% of LV stroke work, respectively. Approximately 60% of LV stroke work is stored as the potential energy during systole under control, and the ratio decreases to ϳ45% with NP and ϳ80% with MTX. left ventricle circulatory coupling; systemic vascular resistance; arterial and venous reservoirs THE HYDRAULIC WORK GENERATED by the left ventricle (LV) pushes blood into the systemic circulation to provide the metabolic requirements of the organs. Although the amount of LV hydraulic work (i.e., the area of the pressure-volume loop) is not disputed, how this work is dissipated in the systemic circulation is still subject to interpretation. Thus far, the analysis of arterial hemodynamics has been dominated by the Fourier-based impedance method, in which aortic pressure and flow have been treated as the sum of sinusoidal wave trains oscillating about mean values; this construct led to the separation of LV hydraulic work into oscillatory work and work related to mean pressure and flow. However, it is difficult to directly relate either to the energy dissipated by the individual components of the serial resistive network.We recently proposed a new approach to the systemic circulation, using the principle of Otto Frank's windkessel (8, 9), in which arterial reservoir pressure (P A-Res ) is proportional to the instantaneous blood volume. Viewed in the time domain, the arterial reservoir is a hydraulic integrator; the reservoir is charged when inflow exceeds outflow (during systole) and vice ...

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“…Recently, Tyberg et al proposed the reservoir‐excess pressure approach,13 which separates the measured arterial pressure into reservoir and excess‐pressure components 14. The latter, excess pressure integral (XSPI), has been identified as a novel indicator of cardiovascular dysfunction for predicting cardiovascular events in the treated hypertensive individuals,15, 16, 17 and high‐risk18 and stable heart failure patients 19.…”

Section: Introductionmentioning

confidence: 99%

Value of Excess Pressure Integral for Predicting 15‐Year All‐Cause and Cardiovascular Mortalities in End‐Stage Renal Disease Patients

Huang

Cheng

et al. 2017

JAHA

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BackgroundThe excess pressure integral (XSPI), derived from analysis of the arterial pressure curve, may be a significant predictor of cardiovascular events in high‐risk patients. We comprehensively investigated the prognostic value of XSPI for predicting long‐term mortality in end‐stage renal disease patients undergoing regular hemodialysis.Methods and ResultsA total of 267 uremic patients (50.2% female; mean age 54.2±14.9 years) receiving regular hemodialysis for more than 6 months were enrolled. Cardiovascular parameters were obtained by echocardiography and applanation tonometry. Calibrated carotid arterial pressure waveforms were analyzed according to the wave‐transmission and reservoir‐wave theories. Multivariable Cox proportional hazard models were constructed to account for age, sex, diabetes mellitus, albumin, body mass index, and hemodialysis treatment adequacy. Incremental utility of the parameters to risk stratification was assessed by net reclassification improvement. During a median follow‐up of 15.3 years, 124 deaths (46.4%) incurred. Baseline XSPI was significantly predictive of all‐cause (hazard ratio per 1 SD 1.4, 95% confidence interval 1.15‐1.70, P=0.0006) and cardiovascular mortalities (1.47, 1.18‐1.84, P=0.0006) after accounting for the covariates. The addition of XSPI to the base prognostic model significantly improved prediction of both all‐cause mortality (net reclassification improvement=0.1549, P=0.0012) and cardiovascular mortality (net reclassification improvement=0.1535, P=0.0033). XSPI was superior to carotid‐pulse wave velocity, forward and backward wave amplitudes, and left ventricular ejection fraction in consideration of overall independent and incremental prognostics values.ConclusionsIn end‐stage renal disease patients undergoing regular hemodialysis, XSPI was significantly predictive of long‐term mortality and demonstrated an incremental value to conventional prognostic factors.

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Time-domain representation of ventricular-arterial coupling as a windkessel and wave system

Cited by 262 publications

References 36 publications

Arterial stiffness or endothelial dysfunction as a surrogate marker of vascular risk

Arterial stiffness or endothelial dysfunction as a surrogate marker of vascular risk

Effects of vasoconstriction and vasodilatation on LV and segmental circulatory energetics

Value of Excess Pressure Integral for Predicting 15‐Year All‐Cause and Cardiovascular Mortalities in End‐Stage Renal Disease Patients

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