Atherosclerosis is a disease in which deposits, called atherosclerotic plaques, build up in the arterial wall. Their presence can become critical when the plaques restrict blood flow and cause a stroke or a heart attack. Standard interventions to treat plaques and restore blood flow through an artery require the application of mechanical force to keep the plaque from obstructing the lumen. Because the cardiovascular system, and specifically blood vessels, has an essential mechanical function in maintaining health, understanding changes in mechanical behaviors in blood vessels caused by disease is critical. Therefore, studying blood vessel and plaque mechanical behaviors, and treating the tissues as materials, may provide essential information on predicting, treating, or preventing cardiovascular diseases. In this chapter, we discuss the current state of understanding of the mechanical behavior of atherosclerotic plaques. The mechanical behavior of a plaque will depend on its constituent materials and its geometry. We begin by discussing the nature of material properties, followed by a review of general arterial mechanics. Then we describe and discuss the studies that have investigated the mechanical responses of atherosclerotic plaques under different loading conditions. In summary, it is clear that our comprehension of the mechanical behavior of atherosclerotic plaque has made enormous advances in recent years. Unfortunately, there are still large gaps in our understanding of many aspects of cardiovascular disease: we still require better knowledge of plaque material properties and behaviors.
Arteries play a critical role in human health, and consequently are extensively studied as a biological component. However, the primary function of arteries is mechanical; they conduct blood through the body. Therefore, arteries, and their structure-function relationships, must also be studied as biomaterials.
Collagen and elastin are the primary load-bearing components of arteries. Elastin is a low strength, highly elastic, fibrous material and collagen is a stiffer material, generally present as wavy fibers when unstretched. Together, they account for the material response of arteries under tensile load. Arteries, and other soft tissues, exhibit a two-part material response to tensile load. There is an initial low stiffness response at low stretch followed by a high stiffness response at higher stretch. It has been proposed that the low stiffness response is dominated by the elastin in the material and the high stiffness response is dominated by collagen [1]. The elastin accounts for the initial low stiffness response of the material, until the wavy collagen fibers straighten and become engaged, at which point the material transitions to its higher stiffness response. It is important to understand the role of the individual collagen and elastin components and how they contribute to the overall mechanical response of the arteries. Further, it is important to understand how specific biochemical processes that occur with age and disease affect the mechanical response of the individual collagen and elastin components and consequently the overall mechanical response of the arteries. This knowledge will increase our understanding of arterial mechanical response and how this response changes arterial function in health and disease.
More than 235,000 pacemakers and 130,000 implantable cardioverter defibrillators (ICD) were implanted in the United States in 2009 [1] for the treatment of various cardiac arrhythmias. Traditional pacemakers and ICDs deliver therapy to the patient through a transvenous lead that extends from a subcutaneously-implanted pulse generator, through the subclavian or cephalic vein, the superior vena cava (SVC), and into the heart. Attachment of the distal tip of the lead into the cardiac muscle is accomplished through either an active fixation mechanism where a metal helix is screwed into the cardiac wall at the time of implantation, or a passive fixation mechanism where silicone tines are ensnared by the fibrous trabeculae within the heart. Implantation of both active and passive leads is aided by the insertion of a stylet, or thin wire, into the lead to provide additional stiffness and steerability as the device is pushed through the vasculature and to the implant site.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.