Fibroblasts account for about two-thirds of the myocardial cell population, whereas myocardiocytes account for about two-thirds of the myocardial mass. Myocardial remodeling in ischemic and nonischemic myocardial disease involves myocardiocytes, other myocardial tissue cells (especially fibroblasts and endothelial cells), and the extracellular matrix.

Specifically, collagen is secreted by fibroblasts as procollagen into the extracellular matrix, where proteases remove the carboxy-terminal amino acid propeptide, which will subsequently be degraded by matrix metalloproteases (MMPs), which in turn are regulated by the tissue inhibitor of metal loproteases (TIMP). Under pathological conditions, the cardiac interstitium may increase due to diffuse deposition of collagen fibers, edema (e.g., secondary to an inflammatory process), or pathological deposition of proteins that physio logically are not present in the cardiac extracellular matrix (such as amyloid). Recent studies have shown that activation of the renin–angiotensin–aldosterone system within cardiac tissue plays a central role in fibroblast activation and colla gen deposition.

Cardiac fibrosis is generally defined as the proliferation of fibroblasts with increased deposition of cardiac muscle collagen fibers or (more rarely) fibrotic thickening of the heart valves. Fibrosis makes the heart muscle stiffer and less elastic, reducing the ability of the ventricles to dilate (ventricular diastolic dysfunction). In addition, fibrosis can affect the heart valves leading to valve dysfunction (stenosis and/or insufficiency).

Myocardial fibrosis can originate through two distinct pathophysiologic processes that result in two different phenotypes:

- Fibrosis can result from the loss of myocardial tissue (e.g., due to an extensive myocardial infarction), which must be considered as an actual scar (reparative or replacement fibrosis);

- In non-ischemic myocardiopathies, generally on a chronic inflammatory basis, an increase in the interstitial matrix is produced, which is generalized to the whole ventricle (or to a large part of it). This type of fibrosis is, therefore, called interstitial and is of reactive type and originates in the areas surrounding the blood capillaries from where it then radiates to the entire myocardial tissue.

The death of myocardiocytes and their replacement with fibrotic tissue cause important alterations in cardiac function. Both increased extracellular synthesis and decreased extra cellular matrix can cause increased ventricular wall stiffness, the most important cause of ventricular diastolic dysfunction. In addition, extracellular matrix deposition between myocardiocytes can alter the propagation of electrical impulses through the myocardium, causing both abnormalities of contraction and cardiac arrhythmias, which can also be fatal. Finally, inflammatory edema and fibrotic tissue deposition around the perivascular areas, by slowing the flow of oxygen and nutrients to the myocardiocytes, trig ger the vicious cycle that supports the progression of myocardial remodeling.

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اخبار العتبة العباسية المقدسة

قسم شؤون المعارف ينظم دورة متقدمة في تحقيق المخطوطات لملاكاته

قسم الشؤون الفكرية يصدر العدد العشرين من مجلة دراسات إفريقية

المجمَع العلمي يكرم الأساتذة المشاركين في مشروع الدورات القرآنية الصيفية في كربلاء

العتبة العباسية المقدسة تختتم فعاليات البرنامج المركزي الأسبوعي لمنتسبيها

المزيد

الآخبار الصحية

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تحذير: مرض السكري يسرق طاقة قلبك

حقيقة صادمة.. لماذا يجب أن تتوقف عن شراء الجزر الصغير؟

بعد عمر الستين.. توقيت وجبة الإفطار مؤشر على صحتك

المزيد

الآخبار التكنلوجية

تركيب مقعد الطفل بأمان في سيارتك: دليل كامل وسهل

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أخيرا.. إنستغرام يصل رسميا إلى آيباد

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المزيد

مواضيع ذات صلة

Galectin-3

Biomarkers of Collagen Synthesis and Degradation

stool for leukocytes (White blood cell stool test, Fecal leukocyte stain, Stool for white cells)

stool culture (Stool for culture and sensitivity [C&S], Stool for ova and parasites [O&P])

stool cancer screening (stool for occult blood, Stool for OB, Fecal occult blood test [FOBT], Fecal immunotest [FIT], DNA stool sample)

Biomarkers of Myocardial Remodeling and Fibrosis

Pathophysiological and Clinical Interpretations of Changes in circulating BNP/NTproBNP

sputum cytology

sodium (Na), urine

Sims-Huhner test (Postcoital test, Postcoital cervical mucus test, Cervical mucus sperm penetration test)

Quality Specifications of Troponin Measurement Methods

Clinical Relevance of Troponins Measurement