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Contribution of the Arterial System and the Heart to Blood Pressure during Normal Aging - A Simulation Study.

Maksuti E, Westerhof N, Westerhof BE, Broomé M, Stergiopulos N - PLoS ONE (2016)

Bottom Line: In the present study we quantified the blood pressure changes in normal aging by using a Windkessel model for the arterial system and the time-varying elastance model for the heart, and compared the simulation results with data from the Framingham Heart Study.Our results show that not only the arterial system, but also the heart, contributes to the changes in blood pressure during aging.The changes in arterial properties initiate a systolic pressure increase, which in turn initiates a cardiac remodelling process that further augments systolic pressure and mitigates the decrease in diastolic pressure.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.

ABSTRACT
During aging, systolic blood pressure continuously increases over time, whereas diastolic pressure first increases and then slightly decreases after middle age. These pressure changes are usually explained by changes of the arterial system alone (increase in arterial stiffness and vascular resistance). However, we hypothesise that the heart contributes to the age-related blood pressure progression as well. In the present study we quantified the blood pressure changes in normal aging by using a Windkessel model for the arterial system and the time-varying elastance model for the heart, and compared the simulation results with data from the Framingham Heart Study. Parameters representing arterial changes (resistance and stiffness) during aging were based on literature values, whereas parameters representing cardiac changes were computed through physiological rules (compensated hypertrophy and preservation of end-diastolic volume). When taking into account arterial changes only, the systolic and diastolic pressure did not agree well with the population data. Between 20 and 80 years, systolic pressure increased from 100 to 122 mmHg, and diastolic pressure decreased from 76 to 55 mmHg. When taking cardiac adaptations into account as well, systolic and diastolic pressure increased from 100 to 151 mmHg and decreased from 76 to 69 mmHg, respectively. Our results show that not only the arterial system, but also the heart, contributes to the changes in blood pressure during aging. The changes in arterial properties initiate a systolic pressure increase, which in turn initiates a cardiac remodelling process that further augments systolic pressure and mitigates the decrease in diastolic pressure.

No MeSH data available.


Related in: MedlinePlus

Scheme of the events occurring during normal aging, used to guide the model’s parameters selection.The loop Hypertrophy–Pressure-volume relations–Systolic pressure is repeatedly carried out until stable pressures and volumes are obtained.
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pone.0157493.g002: Scheme of the events occurring during normal aging, used to guide the model’s parameters selection.The loop Hypertrophy–Pressure-volume relations–Systolic pressure is repeatedly carried out until stable pressures and volumes are obtained.

Mentions: In order to preserve wall stress in Eq (1) and considering a constant lumen radius as in concentric remodelling [7], wall thickness increase must be proportional to the increase in systolic pressure. Successively, we assumed that the increased wall thickness causes a directly proportional increase of both Ees and Eed (ΔPsys = ΔEes = ΔEed). The second rule was that Ped was increased such that the end-diastolic volume remained constant, as reported by Lakatta [5]. The increased wall thickness resulted in an increase in systolic pressure that, in turn, caused more hypertrophy. Ees, Eed and Ped were then increased again, and so on until equilibrium was obtained (changes less than 1 mmHg or 1 mL). A summary of the reasoning that guided the parameter selection is presented in Fig 2. Simulation results for aortic blood pressure over the age range were then compared with clinical pressure data from the Framingham Heart Study reported by Franklin et al. [1], using the mean value between normotensive groups 1 and 2 (Figure 3 in Franklin et al. [1]). In order to account for systolic pressure amplification at the brachial level, we added (for each decade) the average systolic pressure amplification reported by Avolio et al. [23] to the calculated central aortic systolic pressure.


Contribution of the Arterial System and the Heart to Blood Pressure during Normal Aging - A Simulation Study.

Maksuti E, Westerhof N, Westerhof BE, Broomé M, Stergiopulos N - PLoS ONE (2016)

Scheme of the events occurring during normal aging, used to guide the model’s parameters selection.The loop Hypertrophy–Pressure-volume relations–Systolic pressure is repeatedly carried out until stable pressures and volumes are obtained.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920393&req=5

pone.0157493.g002: Scheme of the events occurring during normal aging, used to guide the model’s parameters selection.The loop Hypertrophy–Pressure-volume relations–Systolic pressure is repeatedly carried out until stable pressures and volumes are obtained.
Mentions: In order to preserve wall stress in Eq (1) and considering a constant lumen radius as in concentric remodelling [7], wall thickness increase must be proportional to the increase in systolic pressure. Successively, we assumed that the increased wall thickness causes a directly proportional increase of both Ees and Eed (ΔPsys = ΔEes = ΔEed). The second rule was that Ped was increased such that the end-diastolic volume remained constant, as reported by Lakatta [5]. The increased wall thickness resulted in an increase in systolic pressure that, in turn, caused more hypertrophy. Ees, Eed and Ped were then increased again, and so on until equilibrium was obtained (changes less than 1 mmHg or 1 mL). A summary of the reasoning that guided the parameter selection is presented in Fig 2. Simulation results for aortic blood pressure over the age range were then compared with clinical pressure data from the Framingham Heart Study reported by Franklin et al. [1], using the mean value between normotensive groups 1 and 2 (Figure 3 in Franklin et al. [1]). In order to account for systolic pressure amplification at the brachial level, we added (for each decade) the average systolic pressure amplification reported by Avolio et al. [23] to the calculated central aortic systolic pressure.

Bottom Line: In the present study we quantified the blood pressure changes in normal aging by using a Windkessel model for the arterial system and the time-varying elastance model for the heart, and compared the simulation results with data from the Framingham Heart Study.Our results show that not only the arterial system, but also the heart, contributes to the changes in blood pressure during aging.The changes in arterial properties initiate a systolic pressure increase, which in turn initiates a cardiac remodelling process that further augments systolic pressure and mitigates the decrease in diastolic pressure.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.

ABSTRACT
During aging, systolic blood pressure continuously increases over time, whereas diastolic pressure first increases and then slightly decreases after middle age. These pressure changes are usually explained by changes of the arterial system alone (increase in arterial stiffness and vascular resistance). However, we hypothesise that the heart contributes to the age-related blood pressure progression as well. In the present study we quantified the blood pressure changes in normal aging by using a Windkessel model for the arterial system and the time-varying elastance model for the heart, and compared the simulation results with data from the Framingham Heart Study. Parameters representing arterial changes (resistance and stiffness) during aging were based on literature values, whereas parameters representing cardiac changes were computed through physiological rules (compensated hypertrophy and preservation of end-diastolic volume). When taking into account arterial changes only, the systolic and diastolic pressure did not agree well with the population data. Between 20 and 80 years, systolic pressure increased from 100 to 122 mmHg, and diastolic pressure decreased from 76 to 55 mmHg. When taking cardiac adaptations into account as well, systolic and diastolic pressure increased from 100 to 151 mmHg and decreased from 76 to 69 mmHg, respectively. Our results show that not only the arterial system, but also the heart, contributes to the changes in blood pressure during aging. The changes in arterial properties initiate a systolic pressure increase, which in turn initiates a cardiac remodelling process that further augments systolic pressure and mitigates the decrease in diastolic pressure.

No MeSH data available.


Related in: MedlinePlus