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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3612_Библиотеки_им_академика_М_И_Перельмана
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Key Questions in CONGENITAL CARDIAC SURGERY
TAPVR total anomalous pulmonary venous return
TAV tricuspid aortic valve
TCPC total cavopulmonary connection
TDI tissue Doppler indices
t.d.s.
TEG® thromboelastography
нЙк=ЗбЙ=лмгЙеЗмл
, three times a day
®
TGA transposition of the great arteries
THAM tromethamine
TIMI Thrombolysis in Myocardial Infarction
TNPAI Total NeoPulmonary Artery Index
TOE transoesophageal echocardiography
TOF tetralogy of Fallot
TPN total parenteral nutrition
Tr trachea
TR tricuspid regurgitation
TRALI transfusion-associated lung injury
TRV true right ventricle
TTA true tricuspid annulus
TTE transthoracic echocardiography
TV tricuspid valve; truncal valve
TVO true valve orifice
Tx transplant
TXA tranexamic acid
UAV unicuspid aortic valve
uAVSD unbalanced atrioventricular septal defect
UNOS United Network for Organ Sharing
VA ventriculo-arterial
VACTERL vertebral anomalies, anal atresia, cardiac defects,
tracheoesophageal fistula and/or oesophageal atresia,
renal and radial anomalies, and limb defects
VAD ventricular assist device
VAP ventilator-associated pneumonia
VF ventricular fibrillation
VIF ventriculo-infundibular fold
V/Q ventilation/perfusion
VSD ventricular septal defect
VT ventricular tachycardia
VTE venous thromboembolism
VA veno-arterial
VS ventricular septum
VV vertical vein; veno-venous
WPW Wolff-Parkinson-White
ZBUF zero-balance ultrafiltration
Chapter 1
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Congenital cardiac anatomy
Robert H. Anderson, Diane E. Spicer
1 What are the embryological origins of the components
of the definitive heart?
The primary and secondary heart fields represent the heart-forming
•
area of the mesodermal layer of the embryonic disc.
Cardiomyocytes migrate from the primary heart field to produce a
•
linear tube within the pericardial cavity (Figure 1), which is
responsible for forming the left ventricle and part of the ventricular
septum.
Developing
right ventricle
1
Presumptive
left ventricle
Figure 1. Scanning electron micrograph of a
mouse embryo on the 9th day of development
demonstrating an essentially straight linear tube,
which is eventually responsible for formation of
little more than the definitive left ventricle.
Developing
atrial component
Key Questions in CONGENITAL CARDIAC SURGERY
With ongoing development, new material from the second heart field
•
invades the pericardial cavity at both the venous and arterial poles of
the linear tube. This is responsible for formation of the atrioventricular
canal and the primary atrial chamber at the venous pole, and the
primordium of the right ventricle, along with the outflow tract, at the
arterial pole (Figure 2).
Developing
right ventricle
2
Developing
left ventricle
Developing
outflow tract
Figure 2. Scanning electron micrograph of a
mouse embryo during the 10th day of
development demonstrating looping of the
ventricular component of the linear tube in front of
the developing atrial component, produced by
ongoing addition of material from the heartforming areas at both the arterial and venous
poles. Ballooning from the cavity at the atrial level
then produces the atrial appendages (white
stars), while ballooning from the ventricular loop
produces the apical components of the
developing right and left ventricles.
Ingrowth at both poles results in lengthening of the tube, which
•
contributes to formation of the ventricular loop. Subsequent to
looping, the tube retains a solitary lumen, which is lined with
endocardial jelly. At this early stage, the entirety of the tube, including
the outflow tract, possesses exclusively myocardial walls.
1 Congenital cardiac anatomy
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
The cardiomyocytes forming the walls of the tube have their own
•
phenotype and can be recognised as forming primary myocardium.
The definitive atrial and ventricular chambers are formed by
expansion of pouches from the cavity of the primary tube, with the
newly formed walls built from phenotypically different
cardiomyocytes, which give rise to secondary, or chamber,
myocardium.
Outpouching or ballooning of the primary atrial chamber occurs in a
•
symmetrical fashion and gives rise to the atrial appendages (Figure
2).
The ventricular pouches, in contrast, balloon in series, one from the
•
inlet of the ventricular loop, and the other from the outlet (Figure 3).
Dorsal
mesocardium
AV canal
Outlet
Pharyngeal
mesenchyme
Inlet
Figure 3. Episcopic image of a mouse embryo
during the 11th day of development
demonstrating ballooning of the atrial
appendages (large white arrows) in parallel from
the atrial component of the primary tube, while
the ventricular components are ballooning
apically from the inlet and outlet components of
the ventricular loop. At this initial stage, the
atrioventricular (AV) canal opens exclusively to
the inlet part of the loop.
3
Key Questions in CONGENITAL CARDIAC SURGERY
The pouch ballooning from the inlet of the loop will become the apical
component of the left ventricle, while the ballooning from the outlet
component provides the apical part of the right ventricle. The apical
muscular ventricular septum appears concomitant with the formation
of the two pouches.
By the time the ballooning has taken place, the endocardial jelly has
•
itself undergone a process of endothelial-to-mesenchymal
transformation, producing cushions in the atrioventricular canal and
throughout the outflow tract. These cushions will eventually remodel
to become the cardiac valves.
Additional remodelling within the lumen of the initial primary heart
•
tube then permits the right atrium to gain access to the developing
right ventricle by expansion of the atrioventricular canal (Figure 4),
with the aorta subsequently being transferred to the left ventricle.
Inferior AV cushion
4
Developing RV
Primary atrial
septum
Developing LV
Figure 4. Episcopic image of a mouse embryo
during the 12th day of development
demonstrating expansion of the atrioventricular
(AV) canal, which permits the right atrium to
connect directly with the cavity of the developing
right ventricle (large white arrow).
1 Congenital cardiac anatomy
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Only after this remodelling has taken place is it possible to close the
•
embryonic interventricular communication, thereby completing the
separation of the systemic and pulmonary ventricular blood streams.
2 Describe the connection of the atrial chambers with
the ventricular mass and the ventricles with the arterial
trunks
The key part of the analysis of congenitally malformed hearts is to
•
describe the arrangement of the ‘segments’ (atrial, ventricular and
arterial components) and how they are joined together.
Subsequent to remodelling of the embryonic interventricular
•
communication, the cavities of the atrial chambers are in continuity
with those of the underlying ventricles, whilst the cavities of the
ventricles are continuous with those of the intrapericardial arterial
trunks.
The walls of the various components, however, are not directly
•
contiguous, due to the presence of ‘connecting segments’, with
atrioventricular canal myocardium interposing between the walls of
the atrial segment and the inlet of the ventricular loop, while the
proximal part of the outflow tract (conus) is supported exclusively by
the developing right ventricle (Figure 5).
5
eмг~е=Ф=`~кеЙЦбЙ=лн~ЦЙ=NP
Left atrium
AV canal
Right atrium
Left ventricle
Conus
Figure 5. Episcopic image of a human embryo during
the 6th week of development demonstrating the
developing atrioventricular junctions and the proximal
part of the outflow tract (conus).
Key Questions in CONGENITAL CARDIAC SURGERY
With ongoing development, the myocardium of the atrioventricular
•
canal becomes incorporated into the atrial chambers, forming the
vestibules of the tricuspid and mitral valves.
The proximal myocardium of the outflow tract (conus) forms the
•
myocardium supporting the arterial roots above their respective
ventricles, and is an integral part of the ventricular myocardium.
Subsequent to these changes, it is possible to recognise the
•
definitive atrioventricular and ventriculo-arterial junctions, which
delimit the extent of the ventricular mass.
Hence, the cavities of the atrial chambers connect with those of the
•
ventricles across the atrioventricular junction, and the chambers of
the ventricles are in direct connection with those of the arterial
trunks.
It is less accurate to use the term ‘alignments’ to describe these
•
features, since the cavities of the atrial and ventricular chambers can
be aligned one to the other, as in tricuspid atresia, without being
connected (Figure 6).
6
Right atrium
Right ventricle
Figure 6. Macroscopic image demonstrating alignment of the
right atrium with an incomplete right ventricle in a patient with
tricuspid atresia but the absence of connection between the
atrial and ventricular cavities.
3 What are heterotaxy and isomerism?
Heterotaxy is defined as an abnormal arrangement of the internal
•
thoracic or abdominal organs across the left-right axis of the body.
1 Congenital cardiac anatomy
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Most complex congenital cardiac lesions are found in hearts with
the variant of so-called heterotaxy in which there is evidence, in the
thorax, of an isomeric arrangement of all or parts of the organs.
Isomerism describes the situation in which the right- and left-sided
•
structures within the body are mirror images of each other. The
hands are the perfect example of bodily isomerism. In the mirrorimaged arrangement, often described as ‘situs inversus’, all the
organs are lateralised, but are positioned in mirror-imaged fashion
compared to the usual arrangement. In the isomeric arrangement,
seen best in the thoracic organs, the lungs and bronchi, and the
atrial appendages, are mirror images of each other in the same
individual.
Both the isomeric and mirror-imaged variants represent disorders
•
of laterality.
The right and left sides of the body develop their individual
•
anatomical features in response to genes located on the left side of
the developing embryo, such as Cited2 and Pitx2, and which are
prevented from reaching the right side by other genes, such as
Lefty2 and Sonic hedgehog.
Within the heart, it is only the atrial appendages that respond in
•
differential fashion to these genes, which explains why only the
atrial appendages show evidence of isomerism.
As emphasised above, the lungs and bronchi are also able to
•
develop in isomeric or mirror-imaged fashion, but this is not the
case for the abdominal organs, which can develop in a mirrorimaged or jumbled-up fashion.
The syndrome currently described by many as ‘visceral heterotaxy’
•
is best addressed on the basis of the isomeric arrangement of the
lungs, bronchi and atrial appendages, although the isomeric
features are not always universally present.
For appropriate description of the cardiac findings, analysis should
•
begin with establishment of the presence of isomerism, as opposed
to usually arranged or mirror-imaged atrial appendages. This should
then be followed by full sequential segment analysis, with particular
attention paid to the veno-atrial connections, which can never be
anatomically normal in hearts having isomeric appendages,
although the patterns of venous return can be quasi-usual or quasimirror-imaged.
7
Key Questions in CONGENITAL CARDIAC SURGERY
4 What is the significance of ventricular looping?
As new material is added to the initial heart tube by ongoing
•
migration to the arterial and venous poles from the heart-forming
area, the ventricular component of the tube elongates and turns to
the right, which represents ventricular looping.
The next stage of ventricular development is ‘ballooning’ of the
•
apical components of the right and left ventricles from the outlet
and inlet components of the ventricular loop, respectively. With
normal development, this places the right ventricle to the right of
the developing left ventricle.
Rightward expansion of the atrioventricular canal provides the inlet
•
to the developing right ventricle.
This means that, subsequent to the formation of the right ventricular
•
inlet, it is the palmar surface of the right hand that can be placed
on the developing septum, such that the fingers are in the outlet
and the thumb is in the inlet component. This is called right-handed
ventricular topology, and is the consequence of rightward
8
ventricular looping
Should the ventricular part of the developing heart tube loop to the
•
left, then in association with leftward expansion of the
atrioventricular canal, the situation is produced in which it is the
developing left atrium that is placed into continuity with the
developing right ventricle, and the right ventricle is then formed in
leftward position relative to the left ventricle. In this situation, it is
the palmar surface of the left hand, rather than the right, which is
placed on the septal surface of the developing right ventricle with
the thumb in the inlet and the fingers in the outlet. This produces
left-handed ventricular topology (Figure 7).
This means that, in almost all patients with usual atrial arrangement
•
and concordant atrioventricular connections, the ventricular mass
shows right-handed topology. In patients with concordant
atrioventricular connections and mirror-imaged atrial arrangement,
however, the ventricular mass shows left-handed topology.
It then follows that, when the atrioventricular connections are
•
discordant, there is left-handed topology in the setting of usual
atrial arrangement, but right-handed topology with mirror-imaged
atrial arrangement. These conventions are the basis for description
of segmental anatomy in the approach to analysis promoted by Van
Praagh and his colleagues, with the arrangements described as
1 Congenital cardiac anatomy
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Right-handed ventricular topology Left-handed ventricular topology
Figure 7. Features of right-handed (left panel), as opposed to left-
handed ventricular topology (right panel).
(S,L,*) and (I,D,*), the asterisk representing the topological
arrangement of the arterial segment.
For those using sequential segmental analysis, it can be presumed
•
that the topological arrangement of the ventricular mass is in
keeping with the atrioventricular connections.
In the setting of isomerism of the atrial appendages, however, it is
•
necessary always to describe the ventricular topology, since the
atrioventricular connections themselves are always mixed when the
atrial appendages are isomeric (Figure 8).
9
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