Structural and Functional Differences Between Porcine Aorta and Vena Cava

Abstract

Elastin and collagen fibers are the major load-bearing extracellular matrix (ECM) constituents of the vascular wall. Arteries function differently than veins in the circulatory system; however as a result from several treatment options, veins are subjected to sudden elevated arterial pressure. It is thus important to recognize the fundamental structure and function differences between a vein and an artery. Our research compared the relationship between biaxial mechanical function and ECM structure of porcine thoracic aorta and inferior vena cava. Our study suggests that aorta contains slightly more elastin than collagen due to the cyclical extensibility, but vena cava contains almost four times more collagen than elastin to maintain integrity. Furthermore, multiphoton imaging of vena cava showed longitudinally oriented elastin and circumferentially oriented collagen that is recruited at supraphysiologic stress, but low levels of strain. However in aorta, elastin is distributed uniformly, and the primarily circumferentially oriented collagen is recruited at higher levels of strain than vena cava. These structural observations support the functional finding that vena cava is highly anisotropic with the longitude being more compliant and the circumference stiffening substantially at low levels of strain. Overall, our research demonstrates that fiber distributions and recruitment should be considered in addition to relative collagen and elastin contents. Also, the importance of accounting for the structural and functional differences between arteries and veins should be taken into account when considering disease treatment options.

In Vivo MRI Assessment of Blood Flow in Arteries and Veins from Head-to-Toe Across Age and Sex in C57BL/6 Mice

“…In the arteries, there is high-pressure flow, and thus higher blood flow velocity, compared to the low-pressure/slower velocity in the veins. 32 Area and/or velocity differences account for volumetric flow changes and contribute to cyclic circumferential strain of the vessel wall (area) and shear stress on the luminal surface (area and velocity). For this work, alterations in shear stress along the arterial tree were quantified and can provide baseline information for comparison to pathological conditions since alterations in WSS have been implicated in disease localization and progression in atherosclerosis.…”

Cross-sectional areas of deep/core veins are smaller at lower core body temperatures

“…It is important to study both arteries and veins because of their differential influence on convective and conductive processes as well as counter‐current heat exchange. For example: 65–75% of total blood volume is distributed in the venous system (Rothe ; Milnor ); in the arteries, there is high‐pressure flow, and thus higher blood flow velocity, compared to the low‐pressure/slower flow in the veins; and, differences in wall composition and thickness (e.g., the amount, location, and orientation of elastin, collagen, smooth muscle cells (SMC)) affect the stress–strain relationship and thus how an artery or vein will respond to stimuli, such as temperature, as well as the thermal conductivity of the vessel wall itself (Mattson and Zhang ).…”

Structural Integrity of Aortic Scaffolds Decellularized by Sonication Decellularization System

“…The disruption of the spatial organization of collagen and elastin strongly affects the cellular response and mechanical properties of the aorta in response to pulsatile blood flow from the heart [16] [17]. Cellular process in tissues is activated by the interaction with the cell binding sites such as integrin, discoidin, GPVI, and mannose which regulate the cellular activities including adhesion, proliferation, and migration.…”