ENDOCARDIUM
Introduction :
The heart is a muscular pump that propels blood at high
pressure round the body through the blood vessels. The
heart contracts rhythmically and autonomously.
Contractions begin at the apex of the heart .
the heart has three layers :
Epicardium
(tunica adventitia)
Myocardium (tunica media)
Endocardium (tunica intima)
Definition :
The endocardium is the innermost layer of Heart tissue that
lines the chambers of the heart ( Right and Left Atria +
Right and Left Ventricles ).
The endocardial connective tissue is continuous with that in
the myocardial interstitium and valvular leaflets. (1) (2)
Site :
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. (3)
Structure :
The endocardial endothelium is a complete layer with
nuclei protruding into lumina, and greatly attenuated
cytoplasm showing active micropinocytosis. Endothelial
cell junctions characteristically are complex with
interdigitation and overlapping of cytoplasmic processes.
Subendothelial connective tissue is loose and collagenous,
except in heart valves.
Endocardium is thicker in the atria than in the ventricles,
in the left- thanin the corresponding right-sided chambers.
As well as the endothelium and underlying basement
membrane, there is a small layer of loose connective tissue
and some adipose tissue. (3)
Under Microscope :
Function :
The endocardium, which is primarily made up of
endothelial cells, controls myocardial function, so the role
is to control myocardial contractility.
Additionally, the contractility and electrophysiological
environment of the cardiomyocyte are regulated by the
cardiac endothelium.
The endocardial endothelium may also act as a kind of
blood–heart barrier (analogous to the blood–brain barrier),
thus controlling the ionic composition of the extracellular
fluid in which the cardiomyocytes bathe. (4)
Endocarditis
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Endocarditis is an inflammation of the valves of the
heart.
Endocarditis is often caused by the growth of bacteria
on one of the heart valves like the filamentous
fungus, Aspergillus fumigatus
Symptoms can be nonspecific and
include fever, shortness of breath, and weakness.
Patients can also develop anemia, blood in urine,
elevated white blood cell count, and a new heart
murmur.
"Vegetations" may appear on the valves of the heart as
a result (5)
How is endocarditis diagnosed ?
 the exact diagnosis is made by the identification of the
bacteria in a blood culture, in the appropriate clinical
setting.
 The valve vegetations can be detected by
echocardiography (an ultrasound examination of the
heart).
The most accurate method of detecting valve vegetations is
with a procedure called transesophageal echocardiography
(TEE). In this procedure an echo-transducer is placed on the
tip of a flexible endoscope. The endoscope is inserted
through the mouth into the esophagus. The transducer at the
tip of the endoscope is then able to take sound wave
"pictures" of the heart valves located adjacent to the lower
esophagus. It is important to realize that endocarditis may
exist without visible vegetations on the heart valve.
How it can be treated ?
The mainstay of treatment is aggressive antibiotics,
generally given intravenously, usually for 4-6 weeks. The
duration and intensity of treatment depends on the severity
of the infection and the type of bacterial organism
responsible. In cases where the valve has been severely
damaged by the infection, resulting in severe valve
dysfunction, surgical replacement of the valve may be
necessary. Response to treatment is indicated by a reduction
in fever, negative blood bacterial cultures, and findings on
echocardiography.(6)
References :
(1) https://study.com/academy/lesson/endocardium-definitionfunction.html
(2) https://www.histology.leeds.ac.uk/circulatory/heart.php
(3) https://www.histology.leeds.ac.uk/circulatory/heart.php
https://www.beltina.org/endocardium-definitionand-function/
(4)
(5) https://www.merckmanuals.com/home/heart-and-blood-
vessel-disorders/endocarditis/infective-endocarditis
(6)https://www.medicinenet.com/endocarditis/article.h
tm#what_are_the_symptoms_of_endocarditis