A 2D FE model of the heart demonstrates the role of the pericardium in ventricular deformation

Dept. of Cardiac Sciences, Faculty of Medicine, Univ. of Calgary, Health Sciences Centre, 3330 Hospital Dr. NW, Calgary, AB, Canada.
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 12/2006; 291(5):H2229-36. DOI: 10.1152/ajpheart.00077.2006
Source: PubMed


During pulmonary artery constriction (PAC), an experimental model of acute right ventricular (RV) pressure overload, the interventricular septum flattens and inverts. Finite element (FE) analysis has shown that the septum is subject to axial compression and bending when so deformed. This study examines the effects of acute PAC on the left ventricular (LV) free wall and the role the pericardium may play in these effects. In eight open-chest anesthetized dogs, LV, RV, aortic, and pericardial pressures were recorded under control conditions and with PAC. Model dimensions were derived from two-dimensional echocardiography minor-axis images of the heart. At control (pericardium closed), FE analysis showed that the septum was concave to the LV; stresses in the LV, RV, and septum were low; and the pericardium was subject to circumferential tension. With PAC, RV end-diastolic pressure exceeded LV pressure and the septum inverted. Compressive stresses developed circumferentially in the septum out to the RV insertion points, forming an arch-like pattern. Sharp bending occurred near the insertion points, accompanied by flattening of the LV free wall. With the pericardium open, the deformations and stresses were different. The RV became much larger, especially with PAC. With PAC, the arch-like circumferential stresses still developed in the septum, but their magnitudes were reduced, compared with the pericardium-closed case. There was no free wall inversion and flattening was less. From these FE results, the pericardium has a significant influence on the structural behavior of the septum and the LV and RV free walls. Furthermore, the deformation of the heart is dependent on whether the pericardium is open or closed.

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    • "The space between the parietal and visceral layers of the pericardium contains small amount of fluid called PF. PF has a discernible lubricant function [1] [2]. The composition of normal PF can be described as an ultrafiltrate of plasma except with low protein content [3] [4] [5]. "
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    ABSTRACT: Pericardial fluid (PF) is often considered to be reflection of the serum by which information regarding the physiological status of the heart can be obtained. Some local and systemic disorders may perturb the balance between synthesis and discharge of PF and may cause its aberrant accumulation in the pericardial cavity as pericardial effusion (PE). PE may then lead to an increased intrapericardial pressure from which the heart function is undesirably affected. For some cases, the causes for the perturbance of fluid balance are well understood, but in some other cases, they are not apparent. It may, thus, be helpful to understand the molecular mechanisms behind this troublesome condition to elucidate a clinical approach for therapeutic uses. In this study, protein profiles of PEs from idiopathic pericarditis patients were analyzed. Control samples from patients undergoing elective cardiac surgery (ECS) were included for comparison. In addition to high abundant serum-originated proteins that may not hold significance for understanding the molecular mechanisms behind this disease, omentin-1 was identified and its level was higher for more than two-fold in PE of IP patients. Increased levels of omentin-1 in PE may open a way for understanding the molecular mechanisms behind idiopathic pericarditis (IP).
    04/2014; 2014:942718. DOI:10.1155/2014/942718
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    • "Regarding this issue, two prior animal studies (dog PH model) demonstrated that myocardial tissue at VIPs is prone to encounter pull and increased tension. [20], [21] Also, Spottiswoode et al. reported that paradoxical IVS motion can generate high stresses and strains at VIPs in a non-PH patient. [22] These prior publications, along with the results of the present study, suggest that LGE at VIPs might develop due to the mechanical impact of paradoxical IVS motion on VIPs irrespective of PH. "
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    ABSTRACT: This study investigated the major clinical determinants of late gadolinium enhancement (LGE) at ventricular insertion points (VIPs) commonly seen in patients with pulmonary hypertension (PH). Forty-six consecutive PH patients (mean pulmonary artery pressure ≥25 mmHg at rest) and 21 matched controls were examined. Right ventricular (RV) morphology, function and LGE mass volume at VIPs were assessed by cardiac magnetic resonance (CMR). Radial motion of the left ventricular (LV) wall and interventricular septum (IVS) was assessed by speckle-tracking echocardiography. Paradoxical IVS motion index was then calculated. Univariate and multivariate regression analysis were conducted to characterize the relationship between LGE volume at VIPs and PH-related clinical indices, including the paradoxical IVS motion index. Mean pulmonary arterial pressure (MPAP) of PH patients was 38±9 mmHg. LGE at VIPs was observed in 42 of 46 PH patients, and the LGE volume was 2.02 mL (0.47-2.99 mL). Significant correlations with LGE volume at VIPs were observed for MPAP (r = 0.50) and CMR-derived parameters [RV mass index (r = 0.53), RV end-diastolic volume index (r = 0.53), RV ejection fraction (r = -0.56), and paradoxical IVS motion index (r = 0.77)]. In multiple regression analysis, paradoxical IVS motion index alone significantly predicted LGE volume at VIPs (p<0.001). LGE at VIPs seen in patients with PH appears to reflect altered IVS motion rather than elevated RV pressure or remodeling. Long-term studies would be of benefit to characterize the clinical relevance of LGE at VIPs.
    PLoS ONE 06/2013; 8(6):e66724. DOI:10.1371/journal.pone.0066724 · 3.23 Impact Factor
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    • "To date, there has been a lack of a general purpose, easy replicable, and simplified 2D or 3D model of the torsoembedded heart [5] [6], perhaps because simplified models are considered unable to generate realistic ECG morphologies, despite the fact that such simplified models have been mainly used for cardiac tissue modeling [1] [2]. However, simplified models are easy to replicate, offering a good compromise between computational load and the electrophysiological complexity. "
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    ABSTRACT: We present a computationally efficient three-dimensional bidomain model of torso-embedded whole heart electrical activity, with spontaneous initiation of activation in the sinoatrial node, incorporating a specialized conduction system with heterogeneous action potential morphologies throughout the heart. The simplified geometry incorporates the whole heart as a volume source, with heart cavities, lungs, and torso as passive volume conductors. We placed four surface electrodes at the limbs of the torso: V R , V L , V F and V GND and six electrodes on the chest to simulate the Einthoven, Goldberger-augmented and precordial leads of a standard 12-lead system. By placing additional seven electrodes at the appropriate torso positions, we were also able to calculate the vectorcardiogram of the Frank lead system. Themodel was able to simulate realistic electrocardiogram (ECG) morphologies for the 12 standard leads, orthogonal X, Y, and Z leads, as well as the vectorcardiogram under normal and pathological heart states. Thus, simplified and easy replicable 3D cardiac bidomain model offers a compromise between computational load and model complexity and can be used as an investigative tool to adjust cell, tissue, and whole heart properties, such as setting ischemic lesions or regions of myocardial infarction, to readily investigate their effects on whole ECG morphology.
    Computational and Mathematical Methods in Medicine 04/2013; 2013:134208. DOI:10.1155/2013/134208 · 0.77 Impact Factor
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