SURGICAL ANATOMY OF THE HEART
Heart (cor) is a caval muscular organ with four chambers
which provides the sanguimotion in vessels of greater and
lesser circulation. It is located in the middle mediastinum in
pericardial space. It is located asymmetrically in thoracic
cavity: 2/3 – to the left from the middle plane, and 1/3 – to
the right. The longitudinal axis of the heart goes athwart from
top to bottom, from right to left, and from back to the front.
The borders of the heart
Right border of the heart belongs to the v. cava superior
and right atrium, goes from the upper edge of the 3rd costal
cartilage to the lower edge of the 5th costal cartilage, 2 – 2,5
cm outwards from the right sternal line. From the 5th costal
cartilage the right border passes into the lower one which
complies with the right ventricle. It goes from right to left and
downwards through the 5th intercostal space crossing the
point of attachment to sternum of the right 4th costal cartilage
to the 6th intercostal space leftwards, then crosses 6th costal
cartilage and ends in the 5th intercostal space, by projection of
cardiac apex 0,5 – 1,5 cm before midclavicular line.
Left border of the heart belongs to the left ventricle, left
auricle and truncus pulmonalis. It goes upwards, originating
from the 5th intercostal space archwise to the level of the 3rd
left rib 2 – 3 cm before the edge of sternum. Then it goes to the
2nd intercostal space (2 cm from the left sternal line).
The heart has a basis directed upwards and backwards, and
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apex turned downwards, leftwards and to the front. The basis
is formed by right and left atriums and their posterosuperior
surfaces. V. cava superior and inferior end by the right atrium
of heart basis; the left and right pulmonary veins end by the
left atrium. They form together radix cordis and fix the basis
together. The apex of the heart is formed by the left ventricle
and slightly by the right one. The apex of the heart and two
ventricles are located intrapericardially (completely in
pericardial cavity). The ascending part of aorta, truncus
pilmonalis, and left and right atrial auricles are located in the
pericardial cavity.
Vv. cavae and the both atrial auricles are covered by
pericardium from 3 sides, i. e. – they are located
mesopericardially, as their dorsal side is not covered by
pericardium.
Pulmonary veins and two pulmonary arteries are located
extrapericardially, that is pericardium covers only their anterior
walls.
We can distinguish such surfaces of the heart as: anterior,
sternocostal surface (facies sternocostalis), inferior, diaphragmal
surface (facies diaphragmatica) and pulmonary one. The anterior
and pulmonary surfaces form the blunt edge (margo obtusus)
directed to the left, and anterior and inferior surfaces form the
acute edge (margo acutus) directed to the right.
There are two compartments in the heart: upper (or
superior-right), and inferior (or inferior-left). Atrioventricular
sulcus (coronary sulcus of the heart – sulcus coronarius) is the
border between the segments. The sulcus passes from left to
right, and from up to down. There is the auricle of right atrium
which covers v. cava superior and ascending part of aorta.
Upwards and leftwards the sulcus coronarius passes under
arterial cone which is a part of ventricles passing in aorta (left
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ventricle) and trunkus pulmonalis (right ventricle), and passes
to the dorsal surface. Truncus pulmonalis is the continuation
of arterial cone which penetrates under the inferior surface of
ascending part of aorta in the place of its transition into the
arch (Fig. A.11).
There
is
anterior
interventricular
sulcus
(sulcus
interventricularis anterior), which is located to the left from
the arterial cone and goes along the heart to its top. Turning
backwards and upwards it passes into the posterior
interventricular sulcus (sulcus interventricularis posterior)
which joins coronary sulcus on the top.
The main source of blood supply is the left and right
coronary arteries (a. coronaria dextra et a. coronaria sinistra).
They originate in the Valsalva sinus at the level of upper layers
of left and right semilunar valve. In the phase of systole their
holes are closed by aortic valve, that is the heart receives
blood during diastole when aortic valves are closed.
The left coronary artery (a. coronaria sinistra) goes from the
left aortic sinus to the left part of coronary sulcus and is
divided
into
anterior
interventricular
branch
(r.
interventricularis anterior) and circumflex branch (r.
circumflexus).
The anterior interventricular branch is located in the
anterior interventricular sulcus and goes to the apex of the
heart (cardiac apex) alongside v. cordis magna. At the apex of
the heart it anastomoses with the posterior interventricular
branch from the right coronary artery.
The circumflex branch of the left coronary artery is the
continuation of its main trunk, it rounds the heart from the
left and is observed in the left part of coronary sulcus and on
the posterior surface it anastomoses with the right coronary
artery.
The right coronary artery (a. coronaria dextra) originates in the
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right Valsava sinus and passes between the pulmonary trunk and
right auricle, rounds the heart along the right coronary artery,
passes into posterior surface of the heart and anastomoses with
circumflex branch of the left coronary artery. The largest branch of
right coronary artery is r. interventricularis posterior which is located
in the right coronary artery and goes to the apex of the heart
alongside v. cordis media.
Each coronary artery and their branches have their
branchings. Branches of the left coronary artery supply with
blood the left pulmonary atrium, anterior and most part of
posterior wall of the left ventricle, part of anterior wall of the
right ventricle and anterior part of interventricular septum.
The right coronary artery supplies with blood the right
atrium, the conducting system of the heart, posterior wall of
right and left ventricles, posterior part of interventricular
septum, m. papillaris posterior of the left ventricle.
The branches of left and right coronary arteries anastomose
with each other and form in the heart two arterial circles:
lateral arterial circle located in the coronary sulcus and
longitudinal arterial circle which is located in the anterior and
posterior interventricular sulcus.
There are three types of blood supply of the heart: right
coronary circulation in (90 % of people), left coronary
circulation and balanced circulation. In balanced circulation
both coronary arteries are developed and two posterior
interventricular branches are be observed. In right coronary
circulation the branches of right coronary arteries prevail and
in left coronary circulation – branches of left coronary artries.
Knowing types of blood circulation helps surgeons to choose
correct way in surgical treatment of coronary insufficiency.
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