Application Note | ElastoSens™ Bio
Measuring mechanical properties of pericardial tissue using ElastoSens™ Bio
Introduction
The pericardium plays a central role in modulating how the heart fills, moves, and interacts with its surrounding structures. Its mechanical behavior—defined by properties such as elasticity, stiffness, anisotropy, and resistance to bending—helps maintain the heart’s shape, stabilize its position, and distribute load during every cardiac cycle. In clinical settings, this behavior becomes especially relevant because the pericardium constrains cardiac expansion, influences ventricular coupling, and responds dynamically to changes in pressure. In research environments, its native tissue mechanics guide the design of biomaterials, heart valve substitutes, and computational models of cardiac function.
By studying these mechanical properties, scientists and clinicians can better understand how a healthy pericardium functions, detect early signs of disease, and design therapies that restore or preserve performance.
Key mechanical properties of pericardial tissue
Elasticity and Stiffness
The pericardium exhibits measurable resistance as the heart expands, contributing to its elastic and stiffening behavior during diastolic filling. In vivo pressure measurements—captured through low-profile balloon transducers or orthogonal catheters—show how the tissue responds as the heart increases in volume, revealing how stiffness rises with strain. This elastic constraint supports normal cardiac mechanics by preventing excessive distension while allowing physiological motion.
Anisotropy
Ex vivo mechanical testing consistently demonstrates that the pericardium behaves differently depending on the direction of loading. Planar biaxial testing and computational modeling show that collagen fiber architecture creates direction-dependent mechanical response. This anisotropy influences how the tissue distributes stress, bends, and deforms—an essential factor for both native cardiac function and the performance of pericardial biomaterials used in cardiovascular devices.
Flexural Behavior (Bending Response)
Flexural testing, such as cantilever beam setups, highlights the pericardium’s low resistance to bending. Its thin structure and compliant matrix allow significant out-of-plane deformation under small loads. This bending response is crucial during rapid heart valve and ventricular movements, and is equally important for engineered pericardial materials that must withstand repetitive, low-load flexure without structural damage.
Relationship between diseases and mechanical properties of pericardial tissue
Pericardial Constriction
Constriction significantly alters the mechanical environment of the heart by transforming the normally compliant pericardium into a rigid, non-elastic structure. This increased stiffness restricts diastolic filling, elevates pericardial pressures, and disrupts normal ventricular interaction. Mechanical assessment is essential to understanding how this loss of compliance impacts overall cardiac function.
Cardiac Tamponade
In cardiac tamponade, rapid or excessive fluid accumulation increases intrapericardial pressure and imposes abnormal mechanical load on the heart. As pressure rises in the confined pericardial space, the ventricles can no longer expand normally during diastole. This condition highlights how fluid-induced mechanical changes directly impair cardiac output and require urgent intervention.
Pericardial Effusion
A pericardial effusion alters the heart’s mechanical environment by increasing the distance between the visceral and parietal layers of the pericardium. When fluid volume becomes significant, the added hydraulic pressure reduces compliance and restricts cardiac motion, often progressing toward tamponade physiology if not addressed promptly.
Acute Pericarditis
Inflammation of the pericardium can temporarily stiffen the tissue, reducing its natural elasticity and altering its gliding mechanics. The inflamed layers may generate friction, increase local resistance to deformation, and set the stage for longer-term mechanical changes if scarring develops.
How pericardial tissue mechanics are assessed
In Vivo techniques (Clinics)
In clinical and experimental in vivo settings, the mechanical behavior of the pericardium is evaluated through instruments that measure pressure within the pericardial space. Techniques such as thin, liquid-coupled catheters positioned orthogonally to the epicardial surface and low-profile pericardial balloon transducers allow clinicians and researchers to assess pericardial constraint without significantly disturbing native anatomy. These devices interface with the thin lubricating fluid layer between the heart and pericardium, enabling reliable measurement of pericardial pressure and its influence on cardiac filling and ventricular interaction.
Ex Vivo techniques (Research)
In research environments, the mechanical properties of native or treated pericardial tissue are typically quantified using benchtop mechanical testing systems. Instruments such as planar biaxial tensile testers, uniaxial tensile rigs, and cantilever or beam-style flexural testing setups allow precise characterization of tissue stiffness, anisotropy, and bending behavior. These platforms enable controlled loading and high-resolution deformation measurement, often paired with computational modeling to derive constitutive material parameters. Together, these tools provide a detailed understanding of the pericardium’s structural mechanics for applications ranging from cardiovascular research to biomaterial design.
Case study: Pericardial tissue mechanical characterization with ElastoSens™ Bio
ElastoSens™ Bio: a contactless tool for Ex Vivo tissue testing
In the field of pericardial biomechanics, the ElastoSens™ Bio offers a modern and powerful approach to ex vivo tissue testing. Its non-destructive, continuous viscoelastic measurements allow researchers to characterize the mechanical behavior of pericardium without altering its delicate structure. This enables precise tracking of soft-tissue responses over time and under controlled environmental conditions, providing richer insight than conventional mechanical assays alone.
To demonstrate the capabilities of the ElastoSens™ Bio, we performed an ex vivo study on pericardial tissue samples. The following section outlines the materials and methods used in this experiment, followed by the resulting data, illustrating how the instrument can support advanced biomechanical investigations.
Material and methods
Porcine pericardial membrane was obtained from Sustainable Swine Resources (SSR). Samples were cut into circular punches for loading into ElastoSens™ Bio membrane holders (Figure 1). 2 layers of the membrane were fixed to the holder, making an average thickness of 1.54 mm. To prevent drying, samples were immersed in phosphate-buffered saline (PBS) overnight at 4 °C prior to testing. Each specimen was then placed in the ElastoSens™ Bio instrument at 25 °C for 1 hour to equilibrate. Excess PBS was gently removed before measurement.
Moreover, the porcine pericardial membrane fat was also tested. Specimens with an approximate weight of 3.0 g were sectioned and placed in the macro holders for testing (Figure 2). To prevent drying, samples were also immersed in phosphate-buffered saline (PBS) overnight at 4 °C prior to testing. Each specimen was then placed in the macro holder of the ElastoSens™ Bio instrument and equilibrated at 37 °C for 1 hour. Excess PBS was gently removed before measurement.
The instrument provided real-time viscoelastic parameters, including the shear storage modulus (G′) and the shear loss modulus (G″). For each condition, results were expressed as mean values obtained from three samples, collected from different regions of the same specimen (n = 3).
Figure 1. Porcine pericardial tissue prepared and loaded into the ElastoSens™ Bio membrane holders for non-destructive viscoelastic characterization. The top panel shows the intact pericardial sample prior to sectioning, and the bottom panel shows representative pericardial punctures fixed in the the holders for testing.
Figure 2. Porcine pericardial fat tissue prepared and loaded into the ElastoSens™ Bio macro holders for non-destructive viscoelastic characterization. The top panel shows the intact pericardial fat sample prior to sectioning, and the bottom panel shows representative pericardial portions in the the holders for testing.
Results and discussion
The viscoelastic properties of porcine pericardial membrane were evaluated using the ElastoSens™ Bio testing system (Figure 3). The shear storage modulus (G′) averaged 1624 ± 91 Pa (n = 3). The porcine pericardial fat had a G’ of 1680 ± 99 Pa and shear loss modulus (G’’) of 656 ± 53 Pa (n = 3), indicating a stiffer response than the membrane.
Viscoelastic characterization of the pericardial membrane appears limited in the literature. Most existing studies focus on uniaxial or biaxial tensile testing, which typically requires trimming or flattening the membrane and therefore assesses its response under a different deformation mode. These reported properties are usually direction-dependent tensile moduli in the MPa range. Shear-based measurements, such as those obtained here, provide complementary information on the same intact membrane and allow its viscoelastic response to be evaluated without altering its native structure, which can be valuable when tracking how the material evolves over time or under different conditions.
Viscoelastic data for pericardial adipose tissue also seem relatively sparse. Available adipose rheology studies generally examine subcutaneous or broader visceral fat depots, often using different anatomical locations, temperatures, or testing configurations.
Figure 3: Viscoelastic properties of porcine pericardial membrane: shear storage modulus (G′) obtained with the ElastoSens™ Bio non-destructive testing system (mean ± SD, n=3).
Figure 4: Viscoelastic properties of porcine pericardial membrane fat: shear storage modulus (G′) and shear loss modulus (G’’) obtained with the ElastoSens™ Bio non-destructive testing system (mean ± SD, n=3).
Conclusions and perspectives
The mechanical properties of pericardial tissue—shaped by elasticity, viscoelasticity, and pronounced structural anisotropy—play a central role in regulating how the heart fills, interacts with surrounding structures, and responds to dynamic mechanical loads. Understanding these properties is essential for characterizing pericardial constraints, evaluating biomaterials used in cardiovascular devices, and studying the mechanical environment that supports healthy cardiac motion. Non-destructive viscoelastic testing with the ElastoSens™ Bio enables reliable quantification of pericardial mechanics, capturing key parameters such as shear storage modulus (G′) and shear loss modulus (G″). This approach delivers precise and reproducible data, offering a robust baseline for both cardiovascular research and translational biomechanics.
Beyond these findings, the ElastoSens™ Bio offers unique advantages for pericardial tissue research:
- Simple preparation and gentle handling help preserve the thin, delicate structure of the pericardium, maintaining its native hydration and minimizing mechanical disruption during testing.
- High sensitivity and repeatability allow consistent measurement of viscoelastic properties across different pericardial regions, capturing natural variability related to fiber orientation and tissue thickness.
- Cross-species benchmarking enables direct comparison of pericardial mechanics between animal models and human tissue, supporting translational research in cardiovascular physiology and device development.
- Platform versatility supports testing of native pericardium, decellularized scaffolds, and engineered pericardial substitutes under identical mechanical and environmental conditions.
- Controlled incubation and repeated, non-destructive measurements allow researchers to monitor changes in viscoelastic properties over time—whether driven by enzymatic treatment, chemical crosslinking, hydration changes, or simulated pathological conditions.
- Engineered tissue applications benefit from longitudinal mechanical assessment, enabling teams to follow the maturation, remodeling, or degradation of bioengineered pericardial constructs without sacrificing samples.
Taken together, these capabilities position the ElastoSens™ Bio as a powerful tool for advancing our understanding of pericardial biomechanics, supporting comparative cardiovascular research, and guiding the development of biomaterials and therapies designed to restore or modulate pericardial and cardiac function.
References
Murdock, K., Martin, C., & Sun, W. (2018). Characterization of mechanical properties of pericardium tissue using planar biaxial tension and flexural deformation. Journal of the mechanical behavior of biomedical materials, 77, 148-156.
Devries, G., Hamilton, D. R., Ter Keurs, H. E., Beyar, R., & Tyberg, J. V. (2001). A novel technique for measurement of pericardial pressure. American Journal of Physiology-Heart and Circulatory Physiology, 280(6), H2815-H2822.
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