On the biomechanics of heart valve function

Abstract

Heart valves (HVs) are fluidic control components of the heart that ensure unidirectional blood flow during the cardiac cycle. However, this description does not adequately describe the biomechanical ramifications of their function in that their mechanics are multi-modal. Moreover, they must replicate their cyclic function over an entire lifetime, with an estimated total functional demand of least 3×10 9 cycles. The focus of the present review is on the functional biomechanics of heart valves. Thus, the focus of the present review is on functional biomechanics, referring primarily to biosolid as well as several key biofluid mechanical aspects underlying heart valve physiological function. Specifically, we refer to the mechanical behaviors of the extra-cellular matrix structural proteins, underlying cellular function, and their integrated relation to the major aspects of valvular hemodynamic function. While we focus on the work from the author's laboratories, relevant works of other investigators have been included whenever appropriate. We conclude with a summary of important future trends. KeywordsHeart valves; biomechanics; soft tissue mechanics; cell mechanics; mechanobiology I -Heart Valve Physiologic Function -IntroductionHeart valves (HVs) are fluidic control components of the heart that ensure unidirectional blood flow during the cardiac cycle. Essentially, HVs are passive tissues that are directed to open and close due to inertial forces exerted by the surrounding blood. However, this description does not adequately describe the biomechanical ramifications of their function in that their mechanics are multi-modal and their loading cycle is repeated every second. For example, they must replicate this feat with each heart beat; over a period of 70 years the reader's HVs will open and close nearly 3×10 9 times.Anatomically, there are two types of valves: semilunar and atrio-ventricular (sometimes also known as "sigmodial"). The semilunar valves (pulmonary (PV) and aortic (AV)) prevent For correspondence: Michael S. Sacks, Ph.D., 100 Technology drive, Room 234, University of Pittsburgh, Pittsburgh, PA 15219, Tel: 412-235-5146, Fax: 412-235-5160, Email: msacks@pitt.edu. CONFLICT OF INTERESTThe authors have no conflict of interest, financial or otherwise, that would affect their impartiality of this work.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript retrograde flow back into the ventricles during diastole. Because of their anatomical location, they form nearly a perfec...

On the Presence of Affine Fibril and Fiber Kinematics in the Mitral Valve Anterior Leaflet

“…Yet, we know that the MVAL undergoes very high strain rates during normal operation (29,62). However, it has been observed that valvular tissues are largely strain-rate insensitive (63), so that the responses measured here are likely to represent the in vivo response. The SHG imaging systems has been successfully utilized previously in several studies (7,64,65), although it does have resolution limitations and the results presented herein are necessarily limited by the technique's ability to distinguish fiber structures.…”

Heart Valve Tissue Engineering: A Study of Time Varying Effects and Sample Geometry

“…Another limitation is that it only considered the singular effect of OSS on tissue formation which is thought to be beneficial [7,8,63]. It is however important to note that specimen movement may provide added benefits to tissue formation, by enhancing mass transport of nutrients to the growing tissues.…”

Movement Effects on the Flow Physics and Nutrient Delivery in Engineered Valvular Tissues

“…is suitable for scenarios with small displacement and conversely is not suitable for systems with massive boundary movement such as those that occur in valve leaflets (Kukreja et al, 2008;Oshima et al, 2001;Sacks et al, 2009b).…”

“…elastic solid) (Nguyen and Lim, 2007), but it is not appropriate for systems with randomized boundary movement as it cannot treat arbitrary motion which can occur for example in heart valve disease states (e.g. severe mitral valve prolapse) (Oshima et al, 2001;Sacks et al, 2009b).…”

“…In past decades, NHVs have been thought to be passive structures. However, recent studies have shown tremendous cell and tissue activity occurring on its surface and within its layered structure (Ramaswamy et al, 2010;Sacks et al, 2009a;Sacks et al, 2009b;Salinas et al, 2014a;Salinas et al, 2014b).…”