Quantification of Calcification in Atherosclerotic Lesions

Abstract

Abstract-Calcification can be deposited throughout the vasculature in several forms of calcium phosphate, including calcium hydroxyapatite (CHA). Calcium accumulation in arteries by mineralization and calcium loss from bone by osteoporosis often coexist, and vascular calcification may share common mechanisms with bone remodeling. Deposition of calcification in valves and arteries diminishes the valvular or arterial wall elasticity, a major cause of aneurysm and stenosis. Obstruction of arteries by calcification and other components can lead to heart attack and stroke. Mineralization in the femoral arteries can cause intermittent claudication in the legs, causing decreased mobility. Key Words: calcification Ⅲ atherosclerosis Ⅲ MRI, micro-computed tomography Ⅲ ultrasound C alcium and phosphorus are the most abundant minerals in the body and are involved in a wide range of biochemical pathways, but mostly in the formation of calcium hydroxyapatite (CHA; Ca 10 (PO 4 ) 6 (OH) 2 ). Although CHA is the major natural component of bones and teeth, it can also deposit along with other forms of calcium phosphate in the vasculature with adverse affects. This type of deposit, known as vascular calcification, can ultimately lead to blood vessel stenosis, ischemia, and death. Approximately 90% of patients with cardiovascular disease (CVD) have vascular calcification. Because CVDs are the leading cause of death in the United States, there is considerable interest in understanding the mechanism(s) of vascular calcification and the implications for CVD.Healthy bone exists in a dynamic state of remodeling, requiring osteoblasts that build bone under alkaline conditions and osteoclasts that degrade it under acidic conditions. 1 Cytokines, such as bone morphogenetic proteins (BMPs), interleukin-6, insulin-like growth factor-1, as well as various hormones, regulate bone remodeling. 2 As a consequence of remodeling, bone calcium and phosphate turnover occurs. In this turnover process, resorbed minerals are used to regenerate bone. When the calcium lost in degradation exceeds the calcium deposited in remodeling, there is a net loss of bone mass. With increasing age, the rate of bone degradation exceeds the rate of formation, resulting in osteoporosis, particularly in postmenopausal women, with decreased estrogens, which inhibit cytokines. 3 Some of the calcium and phosphate mobilized by remodeling may become deposited in the arterial wall, leading to atherosclerosis in Ն1 arterial bed.CHA is the most stable form of insoluble calcium phosphate. 4 Under biological conditions, formation of CHA proceeds through noncrystalline amorphous calcium phosphate (ACP), which is stable under alkaline conditions (pH Ն8). Formation of ACP and CHA can be inhibited by many ions and other factors at their normal tissue concentrations. Osteoblast activity regulates formation of CHA, and alkaline phosphatase, which operates under alkaline conditions, is a marker for formation of ACP and its conversion to CHA. 4 Although the mechanism of nucleation of ACP a...

Collagens in the progression and complications of atherosclerosis

“…153 Clinical perspectives on vascular calcification Vascular calcification is readily detected with current imaging technologies. 154 Using electron beam computed tomography, intimal calcification has been reported to affect at least one third of women and half of men over the age of 45. 155 By the age of 70, nearly all patients show some evidence of vascular calcification 156 and the presence of calcification in the coronary arteries, 157,158 or the aortic arch 159 predicts a two to eightfold increase in the risk of coronary events.…”

Serum level of soluble Hsp70 is associated with vascular calcification

“…IMT was measured at three points on a plaque free area of the dorsal wall of both common carotid arteries using linear (7.5-11 MHz) and convex (3.5-5 MHz) transducer of a Toshiba Aplio SSA-770 ultrasound system. The mean value and the maximum IMT was used for calculations (Higgins et al 2005). At the same examination, carotid stenosis was also determined (Grant et al 2003), stenosis with 70% or more were determined as significant.…”

Abdominal ultrasonographic imaging of laboratory animals - Current techniques

“…Η ενδοαγ-γειακή υπερηχογραφία επιτρέπει τον ακριβή προσ διορισμό όχι μόνο της ποσότητας, αλλά και της κατα νομής του ασβεστίου μέσα στο αγγειακό τοίχωμα, κα θώς και τη δυνατότητα κατηγοριοποίησης των υπο στρωμάτων των διαφορετικών πλακών. Η ακρίβεια της ταυτοποίησης τυχόν αθηρωματικών πλακών με τον ενδοαγγειακό υπέρηχο είναι εξαιρετική (Higgins et al 2005). Επίσης, είναι δυνατόν να εκτιμηθεί η επι τυχής ή μη αγγειοπλαστική σε περιφερικά αγγεία ζώ ων εργαστηρίου (Matoon et al 2002), π.χ.…”