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Modeling left ventricular diastolic dysfunction: classification and key indicators.

Luo C, Ramachandran D, Ware DL, Ma TS, Clark JW - Theor Biol Med Model (2011)

Bottom Line: The effects of increasing systolic contractility are also considered.IR-type decreases, but R-type increases the mitral E/A ratio.The model demonstrates that abnormal LV diastolic performance alone can result in decreased LV and RV systolic performance, not previously appreciated, and contribute to the clinical syndrome of HF.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept, Electrical and Computer Engineering, Rice University, Houston, TX 77005, USA.

ABSTRACT

Background: Mathematical modeling can be employed to overcome the practical difficulty of isolating the mechanisms responsible for clinical heart failure in the setting of normal left ventricular ejection fraction (HFNEF). In a human cardiovascular respiratory system (H-CRS) model we introduce three cases of left ventricular diastolic dysfunction (LVDD): (1) impaired left ventricular active relaxation (IR-type); (2) increased passive stiffness (restrictive or R-type); and (3) the combination of both (pseudo-normal or PN-type), to produce HFNEF. The effects of increasing systolic contractility are also considered. Model results showing ensuing heart failure and mechanisms involved are reported.

Methods: We employ our previously described H-CRS model with modified pulmonary compliances to better mimic normal pulmonary blood distribution. IR-type is modeled by changing the activation function of the left ventricle (LV), and R-type by increasing diastolic stiffness of the LV wall and septum. A 5th-order Cash-Karp Runge-Kutta numerical integration method solves the model differential equations.

Results: IR-type and R-type decrease LV stroke volume, cardiac output, ejection fraction (EF), and mean systemic arterial pressure. Heart rate, pulmonary pressures, pulmonary volumes, and pulmonary and systemic arterial-venous O2 and CO2 differences increase. IR-type decreases, but R-type increases the mitral E/A ratio. PN-type produces the well-described, pseudo-normal mitral inflow pattern. All three types of LVDD reduce right ventricular (RV) and LV EF, but the latter remains normal or near normal. Simulations show reduced EF is partly restored by an accompanying increase in systolic stiffness, a compensatory mechanism that may lead clinicians to miss the presence of HF if they only consider LVEF and other indices of LV function. Simulations using the H-CRS model indicate that changes in RV function might well be diagnostic. This study also highlights the importance of septal mechanics in LVDD.

Conclusion: The model demonstrates that abnormal LV diastolic performance alone can result in decreased LV and RV systolic performance, not previously appreciated, and contribute to the clinical syndrome of HF. Furthermore, alterations of RV diastolic performance are present and may be a hallmark of LV diastolic parameter changes that can be used for better clinical recognition of LV diastolic heart disease.

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Comparison of Atrial P-V Loops. Comparison of normal atrial P-V loops (C, solid line) with those occurring in various types of LVDD. In Panels 1 and 2, LV systolic contractility is normal, whereas in Panel 3, systolic contractility is increased. Panel 2 compares a normal (RNSPT) with a stiffened (R) septum in R-type LVDD. Other abbreviations are as in Figure 3.
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Figure 12: Comparison of Atrial P-V Loops. Comparison of normal atrial P-V loops (C, solid line) with those occurring in various types of LVDD. In Panels 1 and 2, LV systolic contractility is normal, whereas in Panel 3, systolic contractility is increased. Panel 2 compares a normal (RNSPT) with a stiffened (R) septum in R-type LVDD. Other abbreviations are as in Figure 3.

Mentions: Figure 12 shows the effect of the different types of LVDD on the instantaneous pressure-volume loops of the right and left atria. Figure 12A1 and B1 show the effects of the three types of LVDD on P-V characteristics of the right and left atria, respectively for the case where the LV has normal ESPVR contractility. In the LA, there is a shift upward and to the right toward higher values of pressure and volume (size) in the simulation sequence C → IR → R → PN (Figure 12B1), whereas RA pressures and volume decrease in the same sequence (Figure 12A1). An increase in the size of the LA relative to control is a common finding in various types of LVDD. In a study on 276 patients, Park et al. [19] have shown that the severity of LVDD correlates well with left atrial dimensions. As the degree of LVDD became more severe, left atrial size and volume increased.


Modeling left ventricular diastolic dysfunction: classification and key indicators.

Luo C, Ramachandran D, Ware DL, Ma TS, Clark JW - Theor Biol Med Model (2011)

Comparison of Atrial P-V Loops. Comparison of normal atrial P-V loops (C, solid line) with those occurring in various types of LVDD. In Panels 1 and 2, LV systolic contractility is normal, whereas in Panel 3, systolic contractility is increased. Panel 2 compares a normal (RNSPT) with a stiffened (R) septum in R-type LVDD. Other abbreviations are as in Figure 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3117805&req=5

Figure 12: Comparison of Atrial P-V Loops. Comparison of normal atrial P-V loops (C, solid line) with those occurring in various types of LVDD. In Panels 1 and 2, LV systolic contractility is normal, whereas in Panel 3, systolic contractility is increased. Panel 2 compares a normal (RNSPT) with a stiffened (R) septum in R-type LVDD. Other abbreviations are as in Figure 3.
Mentions: Figure 12 shows the effect of the different types of LVDD on the instantaneous pressure-volume loops of the right and left atria. Figure 12A1 and B1 show the effects of the three types of LVDD on P-V characteristics of the right and left atria, respectively for the case where the LV has normal ESPVR contractility. In the LA, there is a shift upward and to the right toward higher values of pressure and volume (size) in the simulation sequence C → IR → R → PN (Figure 12B1), whereas RA pressures and volume decrease in the same sequence (Figure 12A1). An increase in the size of the LA relative to control is a common finding in various types of LVDD. In a study on 276 patients, Park et al. [19] have shown that the severity of LVDD correlates well with left atrial dimensions. As the degree of LVDD became more severe, left atrial size and volume increased.

Bottom Line: The effects of increasing systolic contractility are also considered.IR-type decreases, but R-type increases the mitral E/A ratio.The model demonstrates that abnormal LV diastolic performance alone can result in decreased LV and RV systolic performance, not previously appreciated, and contribute to the clinical syndrome of HF.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept, Electrical and Computer Engineering, Rice University, Houston, TX 77005, USA.

ABSTRACT

Background: Mathematical modeling can be employed to overcome the practical difficulty of isolating the mechanisms responsible for clinical heart failure in the setting of normal left ventricular ejection fraction (HFNEF). In a human cardiovascular respiratory system (H-CRS) model we introduce three cases of left ventricular diastolic dysfunction (LVDD): (1) impaired left ventricular active relaxation (IR-type); (2) increased passive stiffness (restrictive or R-type); and (3) the combination of both (pseudo-normal or PN-type), to produce HFNEF. The effects of increasing systolic contractility are also considered. Model results showing ensuing heart failure and mechanisms involved are reported.

Methods: We employ our previously described H-CRS model with modified pulmonary compliances to better mimic normal pulmonary blood distribution. IR-type is modeled by changing the activation function of the left ventricle (LV), and R-type by increasing diastolic stiffness of the LV wall and septum. A 5th-order Cash-Karp Runge-Kutta numerical integration method solves the model differential equations.

Results: IR-type and R-type decrease LV stroke volume, cardiac output, ejection fraction (EF), and mean systemic arterial pressure. Heart rate, pulmonary pressures, pulmonary volumes, and pulmonary and systemic arterial-venous O2 and CO2 differences increase. IR-type decreases, but R-type increases the mitral E/A ratio. PN-type produces the well-described, pseudo-normal mitral inflow pattern. All three types of LVDD reduce right ventricular (RV) and LV EF, but the latter remains normal or near normal. Simulations show reduced EF is partly restored by an accompanying increase in systolic stiffness, a compensatory mechanism that may lead clinicians to miss the presence of HF if they only consider LVEF and other indices of LV function. Simulations using the H-CRS model indicate that changes in RV function might well be diagnostic. This study also highlights the importance of septal mechanics in LVDD.

Conclusion: The model demonstrates that abnormal LV diastolic performance alone can result in decreased LV and RV systolic performance, not previously appreciated, and contribute to the clinical syndrome of HF. Furthermore, alterations of RV diastolic performance are present and may be a hallmark of LV diastolic parameter changes that can be used for better clinical recognition of LV diastolic heart disease.

Show MeSH
Related in: MedlinePlus