Flow in Large Arteries
For centuries, the world within himself fascinated man as much as his near and distant environment. In particular the cardiovascular system was the object of attention of scientific observers like Aristotle and Leonardo da Vinci. However, the concept of t
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Czeslaw M. Rodkiewicz Faculty of Engineering The University of Alberta Edmonton, Alberta, Canada
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INTRODUCTION Introduction For centuries, the world within himself fascinated man as much as
his near and distant environment.
In particular the cardiovascular sys-
tern was the object of attention of scientific observers like Aristotle and Leonardo da Vinci.
However, the concept of the Circulation of the
Blood was clearly presented by W. Harvey in 1628, in his famous De Motu Cordis et Sanguinis in Animalibus.
The evidence provided was almost com-
plete and reached into the present day understanding, except that Harvey could not see the passage of blood from the peripheral arteries to the veins.
He speculated that there must be "pores" at these locations.
These "pores" were in 1661 identified by Malpighi as the capillaries (K.D. Keele, 1978).
Later in 1733 Stephen Hales, the Vicar of Teddington,
C. M. Rodkiewicz (ed.), Arteries and Arterial Blood Flow © Springer-Verlag Wien 1983
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C.M. Rodkiewicz
published the first measurements of arterial blood pressure. The circulatory system, with the heart as the driving force of the double-action pump type, serves to transport and deliver to the tissues those substances which are essential for maintenance of function and to remove the by-products of metabolism. The vessels that arise from the two ventricles and serve as the delivery roots constitute the pulmonary and systemic arteries.
The systemic arteries are considered to be the
primary distributing conduits, however, the smaller arteries, and in particular the arterioles, maintain the blood pressure and are instrumental in regulation of flow rate to the respective tissues.
Elaborate
drawing of the maze of arteries running through the body can be found in any anatomy text book.
Originating at the aorta these distributing con-
duits subdivide the flowing blood into many streams by the Y type bifurcations, most of which are non-symmetric.
The aorta resembles an in-
verted U with one end leadin9 out of the heart and the other end leading down into the abdomen.
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Normally it has three channels branching from the
top of the curve to the head and upper body. The heart produces a periodic or pulsatile flow on the arterial side of the circulatory system.
The amplitude of the flow pulse is largest in
the aorta and becomes gt·adually smaller as the system branches.
The ar-
terial vessels are subjected to higher pressure and pressure variation, and they are thicker and contain more elastin than the venous system. Despite the extra stren9th and elasticity of the arterial walls, it seems likely that a system under the continual wear and tear of a pulsatile flow would be subject to many disorders.
Such is the case; arterial disease
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Introduction
is a very great problem. Among diseases of the arterial tree atherosclerosis is the most common and the most important.
Under the general terms of atherosclerosis
are included several types of tissue changes.
Despite the abundance of
relevant inform
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