This study examines hemodynamic behavior in particular cases of pulmonary hypertension without treatment. Pulmonary hypertension represents an anomalous hemodynamic state and is characterized by an excessively high bl...This study examines hemodynamic behavior in particular cases of pulmonary hypertension without treatment. Pulmonary hypertension represents an anomalous hemodynamic state and is characterized by an excessively high blood pressure in the pulmonary artery. To simulate the hemodynamic abnormalities in pulmonary hypertension under different causes and pathologies, we construct a localized parameter circuit model governed by nonlinear ordinary derivative equations of the human circulatory system. Thus, two special cases are considered, namely pulmonary the artery stenosis and the left ventricular diastolic dysfunction. For each case of pulmonary hypertension development, we determine the relationships between blood pressure and chamber and vessel pressure-volume. When the pulmonary hypertension is due to pulmonary artery stenosis, it appears that the right ventricular pressure increases up to 90 mm Hg, likewise the rise in pulmonary artery resistance induces direct increment in pulmonary artery pressure. However, when the pulmonary hypertension is due to left ventricular diastolic dysfunction, we note that the left atrial pressure and the pulmonary vein pressure augment, leading to the growth of the pulmonary artery blood pressure. The established results within this paper are useful for understanding the hemodynamic mechanism of particular pulmonary hypertension.展开更多
A novel hemodynamic model has been recently introduced,which provides analytical relation-ships between the changes in cerebral blood volume(CBV),cerebral blood flow(CBF),andcerebral metabolic rate of oxy gen(CMRO2),a...A novel hemodynamic model has been recently introduced,which provides analytical relation-ships between the changes in cerebral blood volume(CBV),cerebral blood flow(CBF),andcerebral metabolic rate of oxy gen(CMRO2),and associat ed changes in the tissue concentrationsof oxy-and deoxy-hemoglobin(AO and AD)measured with near-infrared,spectroscopy(NIRS)[S.Fantini,Neuroimage 85,202-221(2014)].This novel model can be applied tomeasurements of the amplit ude and phase of induced hemodynamic oscillations as a function ofthe frequency of oscillation,realizing the novel technique of coherent hemodynamics spectroscopy(CHS)[S.Fantini,Neuroimage 85,202-221(2014);M.L.Pierro et al.,Neuroimage 85,222-233(2014)]:In a previous work,,we have demonstrated an in vivo application of CiHS on hunanSubjects during paced breat hing[M.L.Pierro et al,Neuroimage 85,222-233(2014)].In thiswork,we present a new analysis of the collected data duringpaced breat hing based on a slightlyrevised formulation of the hemodynamic model and ann efficient fitting procedure.While we haveinitially treated all 12 model parameindeependent,we have found that,in this new in-plementation of CHS,the number of independent is eight.In this article,we identifythe eight independent model parameters and,we show that our previous results are consistentwith the new formulation,once the individual parameters of the earlier analysis are combinedinto the new set of independent parameters.展开更多
The dynamics indexes, playing an important role in the cerebral circulation, will be changed significantly compared with their normal range in many cerebrovas-cular disease. The geometrical parameters of cerebrovascul...The dynamics indexes, playing an important role in the cerebral circulation, will be changed significantly compared with their normal range in many cerebrovas-cular disease. The geometrical parameters of cerebrovascular may be detected by DSA or MRA scan, but the hemodynamic parameters, such as, blood flow, artery resistance and compliance must be calculated by building hemodynamics model.The cerebral circular system that has four entrances for blood flow (two carotid and two vertebral arteries) and three communicating arteries is much different from the systematic ststem which has only one entrance, ie. , the aortic. The purpose of this study is to set up a hemodynamics model with lumped parameters to describe the cerebral circulation. From this model, we get its governing equations and present a new method to calculate the hemodynamics indexes in clinical application.展开更多
文摘This study examines hemodynamic behavior in particular cases of pulmonary hypertension without treatment. Pulmonary hypertension represents an anomalous hemodynamic state and is characterized by an excessively high blood pressure in the pulmonary artery. To simulate the hemodynamic abnormalities in pulmonary hypertension under different causes and pathologies, we construct a localized parameter circuit model governed by nonlinear ordinary derivative equations of the human circulatory system. Thus, two special cases are considered, namely pulmonary the artery stenosis and the left ventricular diastolic dysfunction. For each case of pulmonary hypertension development, we determine the relationships between blood pressure and chamber and vessel pressure-volume. When the pulmonary hypertension is due to pulmonary artery stenosis, it appears that the right ventricular pressure increases up to 90 mm Hg, likewise the rise in pulmonary artery resistance induces direct increment in pulmonary artery pressure. However, when the pulmonary hypertension is due to left ventricular diastolic dysfunction, we note that the left atrial pressure and the pulmonary vein pressure augment, leading to the growth of the pulmonary artery blood pressure. The established results within this paper are useful for understanding the hemodynamic mechanism of particular pulmonary hypertension.
基金supported by the National Institutes of Health(Grant No.R01-CA154774)by the National Science Foundation(Award No.IIs-1065154).
文摘A novel hemodynamic model has been recently introduced,which provides analytical relation-ships between the changes in cerebral blood volume(CBV),cerebral blood flow(CBF),andcerebral metabolic rate of oxy gen(CMRO2),and associat ed changes in the tissue concentrationsof oxy-and deoxy-hemoglobin(AO and AD)measured with near-infrared,spectroscopy(NIRS)[S.Fantini,Neuroimage 85,202-221(2014)].This novel model can be applied tomeasurements of the amplit ude and phase of induced hemodynamic oscillations as a function ofthe frequency of oscillation,realizing the novel technique of coherent hemodynamics spectroscopy(CHS)[S.Fantini,Neuroimage 85,202-221(2014);M.L.Pierro et al.,Neuroimage 85,222-233(2014)]:In a previous work,,we have demonstrated an in vivo application of CiHS on hunanSubjects during paced breat hing[M.L.Pierro et al,Neuroimage 85,222-233(2014)].In thiswork,we present a new analysis of the collected data duringpaced breat hing based on a slightlyrevised formulation of the hemodynamic model and ann efficient fitting procedure.While we haveinitially treated all 12 model parameindeependent,we have found that,in this new in-plementation of CHS,the number of independent is eight.In this article,we identifythe eight independent model parameters and,we show that our previous results are consistentwith the new formulation,once the individual parameters of the earlier analysis are combinedinto the new set of independent parameters.
文摘The dynamics indexes, playing an important role in the cerebral circulation, will be changed significantly compared with their normal range in many cerebrovas-cular disease. The geometrical parameters of cerebrovascular may be detected by DSA or MRA scan, but the hemodynamic parameters, such as, blood flow, artery resistance and compliance must be calculated by building hemodynamics model.The cerebral circular system that has four entrances for blood flow (two carotid and two vertebral arteries) and three communicating arteries is much different from the systematic ststem which has only one entrance, ie. , the aortic. The purpose of this study is to set up a hemodynamics model with lumped parameters to describe the cerebral circulation. From this model, we get its governing equations and present a new method to calculate the hemodynamics indexes in clinical application.
