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[1] The endocardium underlies the much more voluminous myocardium , the muscular tissue responsible for the contraction of the heart. The outer layer of the heart is termed epicardium and the heart is surrounded by a small amount of fluid enclosed by a fibrous sac called the pericardium .
The endocardial cushions are thought to arise from a subset of endothelial cells that undergo epithelial-mesenchymal transition, a process whereby these cells break cell-to-cell contacts and migrate into the cardiac jelly (towards the interior of the heart tube). These migrated cells form the "swellings" called the endocardial cushions seen in ...
The endocardial tubes have an intimate proximity to the foregut or pharyngeal endoderm. [1] As folding of the embryo in the horizontal plane initiates in the 4th week of gestation, the endocardial tubes meet in the midline to form the primitive heart tube, which will eventually develop into the histologically definitive endocardium.
This begins with the formation of two endocardial tubes which merge to form the tubular heart, also called the primitive heart tube. The heart is the first functional organ in vertebrate embryos . The tubular heart quickly differentiates into the truncus arteriosus , bulbus cordis , primitive ventricle , primitive atrium , and the sinus venosus .
The Purkinje fibers, named for Jan Evangelista Purkyně, (English: / p ɜːr ˈ k ɪ n dʒ i / pur-KIN-jee; [1] Czech: [ˈpurkɪɲɛ] ⓘ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, [2] just beneath the endocardium in a space called the subendocardium.
Transvenous cardiac pacing (TVP), [1] also called endocardial pacing, is a potentially life-saving intervention used primarily to correct profound bradycardia.It can be used to treat symptomatic bradycardias that do not respond to transcutaneous pacing or to drug therapy.
The IV septum grows upward towards the endocardial cushion. As it grows, a foramen appears, the interventricular foramen , which later is closed by the non-muscular IV septum. Defects in producing the IV septum causes ventricular septal defects , which communicate both ventricles.
This process requires the elongation of the outflow tract as a prerequisite to ensure the correct series of looping and cardiac alignment. [1] The cardiac neural crest complex then colonises in the truncal cushion and is localised to the subendothelial layer prior to spiralisation of the endocardial cushion to form the conotruncal ridges.