Periodicities of cardiac mechanics

1991 ◽  
Vol 261 (2) ◽  
pp. H424-H433
Author(s):  
S. A. Ben-Haim ◽  
G. Fruchter ◽  
G. Hayam ◽  
Y. Edoute

Using a finite-difference equation to model cardiac mechanics, we simulated the stable action of the left ventricle. This model describes the left ventricular end-diastolic volume as a function of the previous end-diastolic volume and several physiological parameters describing the mechanical properties and hemodynamic loading conditions of the heart. Our theoretical simulations demonstrated that transitions (bifurcations) can occur between different modes of dynamic organization of the isolated working heart as parameters are changed. Different regions in the parameter space are characterized by different stable limit cycle periodicities. Experimental studies carried out in an isolated working rat heart model verified the model predictions. The experimental studies showed that stable periodicities were invoked by changing the parameter values in the direction suggested by the theoretical analysis. We propose in the present work that mechanical periodicities of the heart action are an inherent part of its nonlinear nature. The model predictions and experimental results are compatible with previous experimental data but may contradict several hypotheses suggested to explain the phenomenon of cardiac periodicities.

2019 ◽  
Vol 27 (14) ◽  
pp. 1494-1501 ◽  
Author(s):  
Alexander Beaumont ◽  
David Oxborough ◽  
Keith George ◽  
Thomas W Rowland ◽  
Nicholas Sculthorpe ◽  
...  

Aims This study aimed to evaluate left ventricular structure, function and mechanics, in highly-trained, pre-adolescent soccer players compared with age- and sex-matched controls. Design The study design was a prospective, cross-sectional comparison of left ventricular structure, function and mechanics. Methods Twenty-two male soccer players from two professional youth soccer academies (age: 12.0 ± 0.3 years) and 22 recreationally active controls (age: 11.7 ± 0.3 years) were recruited. Two-dimensional conventional and speckle tracking echocardiography were used to quantify left ventricular structure, function and peak/temporal values for left ventricular strain and twist, respectively. Results End-diastolic volume index was larger in soccer players (51 ± 8 mm/(m2)1.5 vs. 45 ± 6 mm/(m2)1.5; p = 0.007) and concentricity was lower in soccer players (4.3 ± 0.7 g/(mL)0.667 vs. 4.9 ± 1.0 g/(mL)0.667; p = 0.017), without differences in mean wall thickness between groups (6.0 ± 0.4 mm vs. 6.1 ± 0.5 mm; p = 0.754). Peak circumferential strain at the base (–22.2% ± 2.5% vs. –20.5% ± 2.5%; p = 0.029) and papillary muscle levels (–20.1% ± 1.5% vs. –18.3% ± 2.5%; p = 0.007) were greater in soccer players. Peak left ventricular twist was larger in soccer players (16.92° ± 7.55° vs. 12.34° ± 4.99°; p = 0.035) and longitudinal early diastolic strain rate was greater in soccer players (2.22 ± 0.40 s–1 vs. 2.02 ± 0.46 s–1; p = 0.025). Conclusions Highly-trained soccer players demonstrated augmented cardiac mechanics with greater circumferential strains, twist and faster diastolic lengthening in the absence of differences in wall thickness between soccer players and controls.


2021 ◽  
Vol 24 (4) ◽  
pp. 382-390
Author(s):  
Roshmi Das ◽  
Ashis Kumar Sarkar

We have proposed here two deterministic models of Jatropha Curcas plant and Whitefly that simulate the dynamics of interaction between them where the distribution of Whitefly on plant follows Poisson distribution.In the first model growth rate of the plant is assumed to be in logistic form whereas in the second model it is taken as exponential form. The attack pattern and the growth of the whitefly are assumed as Holling type II function.The first model results a globally stable state and in the second one we find a globally attracting steady state for some parameter values,and a stable limit cycle for some other parameter values. It is also shown that there exist Hopf bifurcation with respect to some parameter values. The paper also discusses the question about persistence and permanence of the model. It is found that the specific growth rate of both the population and attack pattern of the whitefly governs the dynamics of both the models.


Author(s):  
Tiantian Shen ◽  
Lin Xia ◽  
Wenliang Dong ◽  
Jiaxue Wang ◽  
Feng Su ◽  
...  

Background: Preclinical and clinical evidence suggests that mesenchymal stem cells (MSCs) may be beneficial in treating heart failure (HF). However, the effects of stem cell therapy in patients with heart failure is an ongoing debate and the safety and efficacy of MSCs therapy is not well-known. We conducted a systematic review of clinical trials that evaluated the safety and efficacy of MSCs for HF. This study aimed to assess the safety and efficacy of MSCs therapy compared to the placebo in heart failure patients. Methods: We searched PubMed, Embase, Cochrane library systematically, with no language restrictions. Randomized controlled trials(RCTs) assessing the influence of MSCs treatment function controlled with placebo in heart failure were included in this analysis. We included RCTs with data on safety and efficacy in patients with heart failure after mesenchymal stem cell transplantation. Two investigators independently searched the articles, extracted data, and assessed the quality of the included studies. Pooled data was performed using the fixed-effect model or random-effect model when it appropriate by use of Review Manager 5.3. The Cochrane risk of bias tool was used to assess bias of included studies. The primary outcome was safety assessed by death and rehospitalization and the secondary outcome was efficacy which was assessed by six-minute walk distance and left ventricular ejection fraction (LVEF),left ventricular end-systolic volume(LVESV),left ventricular end-diastolic volume(LVEDV) and brain natriuretic peptide(BNP) Results: A total of twelve studies were included, involving 823 patients who underwent MSCs or placebo treatment. The overall rate of death showed a trend of reduction of 27% (RR [CI]=0.73 [0.49, 1.09], p=0.12) in the MSCs treatment group. The incidence of rehospitalization was reduced by 47% (RR [CI]=0.53[0.38, 0.75], p=0.0004). The patients in the MSCs treatment group realised an average of 117.01m (MD [95% CI]=117.01m [94.87, 139.14], p<0.00001) improvement in 6MWT.MSCs transplantation significantly improved left ventricular ejection fraction (LVEF) by 5.66 % (MD [95% CI]=5.66 [4.39, 6.92], p<0.00001), decreased left ventricular end-systolic volume (LVESV) by 14.75 ml (MD [95% CI]=-14.75 [-16.18, -12.83], p<0.00001 ) and left ventricular end-diastolic volume (LVEDV) by 5.78 ml (MD [95% CI]=-5.78[-12.00, 0.43], p=0.07 ) ,in the MSCs group , BNP was decreased by 133.51 pg/ml MD [95% CI]= -133.51 [-228.17,-38.85], p=0.54, I2= 0.0%) than did in the placebo group. Conclusions: Our results suggested that mesenchymal stem cells as a regenerative therapeutic approach for heart failure is safe and effective by virtue of their self-renewal potential, vast differentiation capacity and immune modulating properties. Allogenic MSCs have superior therapeutic effects and intracoronary injection is the optimum delivery approach. In the tissue origin, patients who received treatment with umbilical cord MSCs seem more effective than bone marrow MSCs. As to dosage injected, (1-10)*10^8 cells were of better effect.


Filomat ◽  
2017 ◽  
Vol 31 (16) ◽  
pp. 5271-5293
Author(s):  
A.K. Pal ◽  
P. Dolai ◽  
G.P. Samanta

In this paper we have studied the dynamical behaviours of a delayed two-species competitive system affected by toxicant with imprecise biological parameters. We have proposed a method to handle these imprecise parameters by using parametric form of interval numbers. We have discussed the existence of various equilibrium points and stability of the system at these equilibrium points. In case of toxic stimulatory system, the delay model exhibits a stable limit cycle oscillation. Computer simulations are carried out to illustrate our analytical findings.


Author(s):  
J. Hoevelmann ◽  
E. Muller ◽  
F. Azibani ◽  
S. Kraus ◽  
J. Cirota ◽  
...  

Abstract Introduction Peripartum cardiomyopathy (PPCM) is an important cause of pregnancy-associated heart failure worldwide. Although a significant number of women recover their left ventricular (LV) function within 12 months, some remain with persistently reduced systolic function. Methods Knowledge gaps exist on predictors of myocardial recovery in PPCM. N-terminal pro-brain natriuretic peptide (NT-proBNP) is the only clinically established biomarker with diagnostic value in PPCM. We aimed to establish whether NT-proBNP could serve as a predictor of LV recovery in PPCM, as measured by LV end-diastolic volume (LVEDD) and LV ejection fraction (LVEF). Results This study of 35 women with PPCM (mean age 30.0 ± 5.9 years) had a median NT-proBNP of 834.7 pg/ml (IQR 571.2–1840.5) at baseline. Within the first year of follow-up, 51.4% of the cohort recovered their LV dimensions (LVEDD < 55 mm) and systolic function (LVEF > 50%). Women without LV recovery presented with higher NT-proBNP at baseline. Multivariable regression analyses demonstrated that NT-proBNP of ≥ 900 pg/ml at the time of diagnosis was predictive of failure to recover LVEDD (OR 0.22, 95% CI 0.05–0.95, P = 0.043) or LVEF (OR 0.20 [95% CI 0.04–0.89], p = 0.035) at follow-up. Conclusions We have demonstrated that NT-proBNP has a prognostic value in predicting LV recovery of patients with PPCM. Patients with NT-proBNP of ≥ 900 pg/ml were less likely to show any improvement in LVEF or LVEDD. Our findings have implications for clinical practice as patients with higher NT-proBNP might require more aggressive therapy and more intensive follow-up. Point-of-care NT-proBNP for diagnosis and risk stratification warrants further investigation.


2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
H Ben-Arzi ◽  
A Das ◽  
C Kelly ◽  
RJ Van Der Geest ◽  
A Chowdhary ◽  
...  

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation HRUK Background. Four-dimensional flow (4D flow) cardiovascular magnetic resonance (CMR) imaging provides quantification of intra-cavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. Myocardial infarction (MI) is known to cause acute alterations in intra-cardiac blood flow but assessments of longitudinal changes are lacking. Purpose. Assess longitudinal changes in LV flow post ST-elevation myocardial infarction (STEMI). Method. Twenty acutely reperfused STEMI patients (13 men, 7 women, mean age 54 ± 9 years) underwent 3T CMR acutely (within 5-7 days) and 3 months post-MI.  CMR protocol included functional imaging, late gadolinium enhancement and 4D flow. Using Q-MASS, LV KE parameters were derived and indexed to LV end-diastolic volume (LVKEiEDV). Based on acute ejection fraction (EF), patients were grouped as follows: preserved (pEF) EF &gt;50%, reduced (rEF) EF &lt;50% including mild (rEF= 40-49%), moderate to severe (EF &lt;40%) impairment.  Results. Out of 20 patients, 13 had rEF acutely (7 mild rEF, 6 moderate to severe rEF). Acute LVKEiEDV parameters varied significantly between pEF and rEF (Table). At 3 months, pEF and mild rEF patients showed a significant (P &lt; 0.05) reduction in average, systolic and peak-A wave LVKEiEDV. Mild rEF patients also had significant (P &lt; 0.05) reduction in minimal and peak-E wave LVKEiEDV. However in patients with moderate to severe rEF in the acute scan, there were no significant change by 3 months (Figure). Conclusion. Following MI, 4D flow LVKE derived biomarkers significantly decreased over time in pEF and mild rEF groups but not in moderate to severe rEF group. 4D flow assessment might provide incremental prognostic value beyond EF assessment alone. Table pEF (n = 7) rEF (n = 13) V1 V2 P-value V1 V2 P-value EF(%) 56 ± 5 55 ± 4 0.40 41 ± 7 47 ± 9 0.01 Infarct Size(%) 31 ± 20 15 ± 9 0.04 18 ± 13† 16 ± 11 0.41 LV KEiEDV parameters Average(µJ/ml) 9 ± 2 7 ± 2 0.02 10 ± 3† 8 ± 3 0.01 Minimal(µJ/ml) 1 ± 0.6 1 ± 0.5 0.46 1.3 ± 0.5 1 ± 0.6 0.03 Systolic(µJ/ml) 10 ± 4 7 ± 2 &lt;0.01 12 ± 4† 7 ± 3 &lt;0.01 Diastolic(µJ/ml) 8 ± 3 7 ± 2 0.13 9 ± 3 8 ± 3 0.09 Peak-E wave(µJ/ml) 22 ± 9 23 ± 8 0.44 20 ± 7 18 ± 10 0.23 Peak-A wave(µJ/ml) 18 ± 10 11 ± 4 0.04 17 ± 9 14 ± 7 0.02 †P &lt; 0.05 V1 comparison between pEF and rEF Abstract Figure


2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
L Zhang ◽  
Y.K Guo ◽  
Z.G Yang ◽  
M.X Yang ◽  
K.Y Diao ◽  
...  

Abstract Background Cardiac magnet resonance (CMR) T1 mapping allows the quantitative characterization of the severity of tissue injury and predict functional recovery in acute myocardial infarction (AMI). Purpose The study aimed to investigate whether native T1 and ECV of infarct myocardium are influenced by microvascular obstruction (MVO) and have predictive value for adverse left ventricular (LV) remodeling post-infarction. Method A cohort of 54 patients with successfully reperfused STEMI underwent CMR imaging at a 3T scanner in AMI and 3 months post-infarction. Native T1 data was acquired using a modified Look-Locker inversion recovery (MOLLI) sequence, and ECV maps were calculated using blood sampled hematocrit. Manual regions-of-interest were drawn within the infarct myocardium to measure native T1 and ECV (native T1infarct and ECVinfarct, respectively). MVO identified as a low-intensity area within the infarct zone on LGE was eliminated. Results MVO was present in 36 patients (66.67%) in AMI. ECVinfarct in patients with MVO was different from those without (58.66±8.71% vs. 49.64±8.82%, P=0.001), while no significant difference in T1infarct was observed between patients with and without MVO (1474.7±63.5ms vs. 1495.4±98.0ms, P=0.352). ECV correlated well with the change in end-diastolic volume (all patients: r=0.564, P&lt;0.001) and predicted LV remodeling in patients with and without MVO (rMVO absent = 0.626, P=0.005; rMVO present = 0.686, P&lt;0.001; all patients: r=0.622, P&lt;0.001); Native T1 was only associated with a 3-month change in LV end-diastolic volume (rMVO absent= 0.483, P=0.042) and predicted LV remodeling in patients without MVO (rMVO absent = 0.659, P=0.003). Furthermore, ECV had an association with LV remodeling (β=0.312, P=0.007) in multivariable logistic analysis. Conclusion Absolute native T1 in infarct myocardium might be affected by MVO but ECV isn't. ECV could predict LV remodeling in MI patients with and without MVO, while native T1 predict it in MI with MVO absent. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): 1·3·5 project for disciplines of excellence, West China Hospital, Sichuan University


Diagnostics ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1403
Author(s):  
Akira Yairo ◽  
Ahmed S. Mandour ◽  
Katsuhiro Matsuura ◽  
Tomohiko Yoshida ◽  
Danfu Ma ◽  
...  

Evaluation of diastolic function is a pivotal challenge due to limitations of the conventional echocardiography, especially when the heart rate is rapid as in rats. Currently, by using color M-mode echocardiography (CMME), intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG) in early diastole can be generated and are available as echocardiographic indices. These indices are expected to be useful for the early diagnosis of heart failure (HF), especially diastolic dysfunction. There have not been any studies demonstrating changes in IVPD and IVPG in response to changes in loading conditions in rats. Therefore, the present study aims to evaluate CMME-derived IVPD and IVPG changes in rats under various loading conditions. Twenty rats were included, divided into two groups for two different experiments, and underwent jugular vein catheterization under inhalational anesthetics. Conventional echocardiography, CMME, and 2D speckle tracking echocardiography were measured at the baseline (BL), after intravenous infusion of milrinone (MIL, n = 10), and after the infusion of hydroxyethyl starch (HES, n = 10). Left ventricular IVPD and IVPG were calculated from color M-mode images and categorized into total, basal, mid-to-apical, mid, and apical parts, and the percentage of the corresponding part was calculated. In comparison to the BL, the ejection fraction, mid-to-apical IVPG, mid IVPG, and apical IVPD were significantly increased after MIL administration (p < 0.05); meanwhile, the end-diastolic volume, E-wave velocity, total IVPD, and basal IVPD were significantly increased with the administration of HES (p < 0.05). The increase in mid-to-apical IVPD, mid IVPD, and apical IVPD indicated increased relaxation. A significant increase in basal IVPD reflected volume overloading by HES. CMME-derived IVPD and IVPG are useful tools for the evaluation of various loading conditions in rats. The approach used in this study provides a model for continuous data acquisition in chronic cardiac disease models without drug testing.


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