Everything about Myocardium totally explained
Myocardium is the
muscular tissue of the
heart.
Relationship to other layers
The other tissues of the heart are:
Composition
The myocardium is composed of specialized
cardiac muscle cells with an ability not possessed by muscle tissue elsewhere in the body. Cardiac muscle, like other muscles, can
contract, but it can also carry an
action potential (for example
conduct electricity), like the
neurons that constitute
nerves. Furthermore, some of the cells have the ability to generate an action potential, known as
cardiac muscle automaticity.
The blood supply of the myocardium is carried by the
coronary arteries.
The myocardium is subject to two opposed electrical subsets of control.
First order electrical control of the myocardium is derived from the sinoatrial node. Propagation of first order control from the sinoatrial node is closely tied to sympathetic discharge. Second order electrical control of the myocardium is closely tied to parasympathetic influence from the spinal vertebral ganglia and vagus nerves.
Pathology
Occlusion of the coronary arteries by
atherosclerosis and/or
thrombosis can lead to
myocardial infarction.
Certain viruses lead to
inflammation of the myocardium, or
myocarditis.
Cardiomyopathies are inherent diseases of the myocardium, many of which are caused by genetic mutations.
Failure of the heart to contract properly (for various reasons) is often termed
heart failure although the proper term for this condition is myocardial failure.
Heart failure is a general term referring to overwhelming heart disease from many causes (for example, myocardial failure, valvular heart disease, increased ventricular stiffness) resulting in the inability of the heart to maintain normal ventricular filling pressure (resulting in
fluid retention,
edema,
pulmonary oedema,
hepatomegaly) and/or reduced blood flow to the body either at rest or during exercise. Myocardial failure resulting in heart failure results in a shortened
life expectancy and decreased
quality of life.
Disease of myocardium
Noncompaction Cardiomyopathy, is when the Myocardium tissue fails to compact as the human embryo develops.
Disease of the myocardium can also be considered to be ischemic (poor blood supply to the heart muscle) or nonischemic, implying disease within the heart muscle itself.
1. Ischemic myocardial disease is well described and is amenable to vessel bypass,
stents, applied
growth factors and many other interventions.
a.
Diabetes is perhaps the best known physiologic model for accelerated ischemic disease of the myocardium.
2. Nonischemic myocardial disease (see also nonischemic cardiomyopathy) is an entirely different entity in myocardial disease.
a. Chagasic heart failure (see also
Carlos Chagas) is perhaps the best known physiologic model in myocardial autonomic insufficiency.
Further Information
Get more info on 'Myocardium'.
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