myocardium


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myocardium

 [mi″o-kar´de-um]
the middle and thickest layer of the heart wall, composed of cardiac muscle. adj., adj myocar´dial.

my·o·car·di·um

, pl.

my·o·car·di·a

(mī'ō-kar'dē-ŭm, -kar'dē-ă), [TA]
The middle layer of the heart, consisting of cardiac muscle.
[myo- + G. kardia, heart]

myocardium

/myo·car·di·um/ (-kahr´de-um) the middle and thickest layer of the heart wall, composed of cardiac muscle.
hibernating myocardium  see myocardial hibernation, under hibernation.
stunned myocardium  see myocardial stunning, under stunning.

myocardium

(mī′ō-kär′dē-əm)
n. pl. myocar·dia (-dē-ə)
The muscular tissue of the heart.

my′o·car′di·al adj.

myocardium

[mī′ōkär′dē·əm]
Etymology: Gk, mys, muscle, kardia, heart
a thick contractile middle layer of uniquely constructed and arranged muscle cells that forms the bulk of the heart wall. The myocardium contains a minimum of other tissue, except blood vessels, and is covered interiorly by the endocardium. The contractile tissue of the myocardium is composed of fibers with the characteristic cross-striations of muscular tissue. The fibers are about one third as large in diameter as those of skeletal muscle and contain more sarcoplasm. They branch frequently and are interconnected to form a network that is continuous except where the bundles and the laminae are attached at their origins and insertions into the fibrous trigone of the heart. Myocardial muscle contains less connective tissue than does skeletal muscle. Specially modified fibers of myocardial muscle constitute the conduction system of the heart, including the sinoatrial node, the atrioventricular (AV) node, the AV bundle, and the Purkinje fibers. Most of the myocardial fibers function to contract the heart. The metabolic processes of the myocardium are almost exclusively aerobic. Many key enzymatic reactions of the heart, such as the citric acid cycle and oxidative phosphorylation, take place in the highly concentrated myocardial sarcosomes. The process of oxidative phosphorylation produces adenosine triphosphate (ATP), the immediate energy source for myocardial contraction. Oxygen, which significantly affects ATP production and contractibility, is a critical metabolic component of the myocardium, which consumes from 6.5 to 10 mL/100 g of tissue per minute. Without this oxygen supply, myocardial contractions decrease in a few minutes. The myocardium maintains a relatively constant level of glycogen in the form of sarcoplasmic granules. Compare epicardium. See also cardiac muscle. myocardial, adj.

my·o·car·di·um

, pl. myocardia (mī'ō-kahr'dē-ŭm, -ă) [TA]
The middle layer of the heart, consisting of cardiac muscle.
[myo- + G. kardia, heart]

myocardium

the muscular wall of the vertebrate heart.

Myocardium

The thick middle layer of the heart that forms the bulk of the heart wall and contracts as the organ beats.

myocardium

cardiac muscle

my·o·car·di·um

, pl. myocardia (mī'ō-kahr'dē-ŭm, -ă) [TA]
The middle layer of the heart, consisting of cardiac muscle.
[myo- + G. kardia, heart]

myocardium

(mī´ōkär´dēəm),
n the thick, contractile middle layer of uniquely constructed and arranged muscle cells (cardiac muscle) that form the bulk of the heart wall.

myocardium

the middle and thickest layer of the heart wall, composed of cardiac muscle.
References in periodicals archive ?
16 were the first to show a 68% regeneration of the infarcted myocardium in rodents in response to injection of Lin-c-Kit+ BMCs [Bone marrow cells]with a delay of 9 days.
The LGE images suggest that these subjects have non-viable myocardium, which developed following a previous silent or overt vascular event.
100 [micro]l plasma and myocardium homogenate of rats in group A, B and D was analyzed using the targeted metabolomic profiling platform.
There diagnostic criteria were as follows: (1) >3 prominent trabecular formations along the left ventricular endocardial border, which are visible in end-diastole, distinct from papillary muscles, false tendons, or aberrant bands, (2) trabeculations move synchronously with the compacted myocardium, (3) trabeculations form the noncompacted part of the two-layer myocardial structure, best visible at endsystole, and (4) perfusion of the intertrabecular spaces from the ventricular cavity is present at end-diastole on color-Doppler echocardiography or contrast echocardiography.
In addition, AlloCSC-01 has displayed a strong tropism for the heart enabling a high retention of cells in the myocardium after intracoronary administration.
Ichida F, Hamamichi Y, Miyawaki T, Ono Y, Kamiya T, Akagi T, Hamada H, Hirose O, Isobe T, Yamada K, Kurotobi S, Mito H, Miyake T, Murakami Y, Nishi T, Shinohara M, Seguchi M, Tashiro S, Tomimatsu H: Clinical features of isolated noncompaction of the ventricular myocardium.
LVNC represents the persistence of multiple trabeculations in the ventricular myocardium with deep intratrabecular spaces due to arrested compaction of the wall.
The outer one was in direct contact with myocardium and was composed of irregularly arranged connective tissue that merge with collagen and elastic fibres surrounding the adjacent cardiac muscle along with Purkinje fibres, blood vessels, and lymphatics.
Adenosine fast-field echo-gradient stress imaging subendocardial perfusion, with exception to stress induced subendocardial hypoenhancement in the apical-anterior lateral wall, extending to the junction with the midchamber myocardium (Figure 5).
The situation in which the myocardium thickens can occur either when the blood pressure is high for long periods of time (hypertensive heart disease), or when a protein or other substance is deposited in the heart muscle.
Generally acceptable indices for LVNCC consideration by cardiac imaging include demonstration of 1) two ventricular layers: the outer compacted and inner noncompacted zone with a maximum ratio of noncompacted to compacted myocardium >2:1 at end-systole in the parasternal short-axis view; 2) deep trabeculations in the left ventricular apex or midventricular segments of the inferior and lateral wall; and 3) color Doppler evidence of flow within the deep muscular recesses.