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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
11 What are the principles of assessing a
cavopulmonary circulation with radiological
imaging?
Prior to surgery, radiological imaging is used for Fontan planning
•
with:
a) CT — which provides an anatomical assessment, especially
looking at branch pulmonary artery stenosis and pulmonary
venous return (Figure 19);
b) MRI — which can be used to assess ventricular function,
valvular regurgitation and pulmonary venous return. In the
presence of a collateral circulation, quantifying collateral flow
is possible by velocity mapping.
Following surgery, radiological imaging is useful in determining the
•
haemodynamic status of the Fontan circulation and the detection of
complications, including:
190
a) CT — which is used to detect cavopulmonary connection
stenosis and thrombosis, pulmonary vein compression by a
dilated right atrium, and pulmonary arteriovenous fistulae;
b) MRI — which is excellent in assessing ventricular function,
evaluating Fontan connections and early detection of
pulmonary artery stenosis. Detecting and quantifying flow
through the patch or a baffle leak, systemic vein to pulmonary
vein collaterals, pulmonary arteriovenous malformations and
fenestrations is also possible. It can also assess thrombosis
on early gadolinium enhancement studies, fibrosis on late
gadolinium enhancement studies and guide interventions,
such as electrophysiology intervention for arrhythmia.
In patients following post-aortic arch and coarctation repair, MRI
•
and CT can be incorporated in the follow-up, with MRI or stress
echocardiography used to identify myocardial ischaemia,
secondary to poor perfusion when the coronary arteries arise from
a diminutive aorta.
5 Congenital cardiac imaging
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A
BC
191
Figure 19. Computed tomography images of an 18-month-old patient with
Shone syndrome, who had previously undergone a Kawashima procedure
and later a bilateral bidirectional Glenn procedure: A) 3D volume-rendered;
and B) coronal images demonstrating a patent connection of the right and left
superior vena cavae to the right and left pulmonary arteries, respectively. A
closure device was later inserted in the azygos connection to the left
pulmonary artery (arrow) that only achieves partial closure (red arrow); C)
coronal image demonstrating persistent hepatic vein drainage to the right
atrium causing mixing of a small amount of desaturated blood with
oxygenated blood.
192
Key Questions in CONGENITAL CARDIAC SURGERY
12 What are the principles of assessing anomalous
pulmonary venous drainage with radiological
imaging?
Unless the anomalous pulmonary vein drains close to the cavo-atrial
•
connection, the diagnosis of assessing anomalous pulmonary venous
drainage by echocardiography can be difficult.
Echocardiography is often used to assess cardiac function and
•
identify any intracardiac shunts, with CT and MRI representing the
best modalities to diagnose assessing anomalous pulmonary venous
drainage (Figures 20 and 21).
AB
C
Figure 20. Cardiac magnetic resonance images demonstrating abnormal
drainage of the right upper pulmonary vein to the superior vena cava with no
significant left-to-right shunt on: A) and B) computed tomography axial images;
and C) magnetic resonance imaging flow velocity mapping with a Qp/Qs ratio
of 1.2.
5 Congenital cardiac imaging
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A
B
C
Figure 21. Radiological images
demonstrating abnormal drainage of the
right lower pulmonary vein to right atrium
on: A) steady-state free precession
magnetic resonance imaging axial
image; B and C) significant left-to-right
shunt on magnetic resonance imaging
flow velocity mapping with a Qp/Qs ratio
of 3.4.
Chest radiographical features of assessing anomalous pulmonary
•
venous drainage may include a Scimitar sign or evidence of
pulmonary artery dilatation and cardiomegaly.
193
194
Key Questions in CONGENITAL CARDIAC SURGERY
13 What are the principles of assessing coarctation of the
aorta and arch hypoplasia with radiological imaging?
In patients with coarctation of the aorta, imaging is used to define the
•
coarctation lesion and also to identify any other coexisting
cardiovascular abnormalities, including bicuspid aortic valve (up to
85%), ventricular septal defects, mitral valve abnormalities,
intracranial aneurysms (Berry aneurysm of the circle of Willis in 35%).
Chest radiograph may demonstrate rib notching (Roesler sign),
•
which is caused by dilated intercostal collateral vessels bypassing
the coarctation and eroding the inferior margins of the ribs (Figure
22). In addition, a ‘figure of 3’ sign can be seen, which is formed by
pre- and post-stenotic dilatation of the coarcted aorta.
Although echocardiography is the modality of choice for diagnosis
•
and follow-up, it has an innate limitation for assessing the thoracic
aorta and complications in this region. Transoesophageal
echocardiography has a better diagnostic field in detailed
examination of the aorta but it is semi-invasive.
A
B
Figure 22. A) Chest radiograph and B) magnified inset of a patient with
coarctation of the aorta demonstrating subcostal bone erosion (rib
notching) secondary to intercostal artery dilatation.
5 Congenital cardiac imaging
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MRI can assess the severity of the coarctation, relationship of the
•
vessel to the neighbouring structures, presence of associated
anomalies, shunt quantitation and presence of collateral vessels,
which is important for surgical planning (Figure 23).
A B
195
Figure 23. Volume-rendered contrast-enhanced magnetic resonance
angiography demonstrating: A) a tight coarctation at the junction of the
distal arch and descending aorta (arrow); and B) dilated internal
mammary and intercostal arteries bridging the stenotic aorta on the
maximum intensity projection (MIP) reconstruction.
MRI is the preferred modality due to the lack of radiation in these
•
often young patients and can detect complications, such as
recoarctation or aneurysm formation.
CT angiography is preferred in patients with a stented coarctation
•
due to the metallic artefacts that prevent accurate assessment of the
stent by MRI. CT may also be used in children who cannot tolerate
MRI.
CT can define the site and morphology of the coarctation, presence
•
of any arch hypoplasia, collateral circulation or associated anomalies.
CT does not, however, provide functional data, such as the gradient
•
across the coarctation.
In the post-intervention patient, CT allows detection of any residual
•
stenosis or recoarctation and collateral vessel formation (Figure 24).
It is also useful in the diagnosis of post-stenting complications, such
196
Key Questions in CONGENITAL CARDIAC SURGERY
as aortic dissection, leaks, in-stent thrombus, stent migration and
stent fracture. CT is the preferred modality to evaluate the coronary
arteries in these patients.
A B
Desc
Ao
Asc
Ao
Figure 24. Radiological imaging following endovascular repair of an
aortic coarctation, with: A) double oblique multiplanar projection
(MPR) computed tomography angiography demonstrating a patent
stent in the distal arch position and dilated descending aorta; and B)
phase contrast magnetic resonance imaging demonstrating a peak
velocity of 1.4m/s at the stent site (arrow) indicating no significant
residual coarctation (B). Asc Ao = ascending aorta; Desc Ao =
descending aorta.
14 What are the principles of assessing interrupted aortic
arch with radiological imaging?
Both CT and MRI can be employed to differentiate between
•
interrupted aortic arch with severe coarctation from aortic arch
hypoplasia that may not be possible by echocardiography.
CTA and CMR can delineate the anatomical features of the different
•
subtypes of interrupted aortic arch and can also be used in
assessing associated anomalies, such as VSD, subaortic stenosis
and other complex lesions.
5 Congenital cardiac imaging
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Multiplanar and volume-rendering reconstruction from CT and/or
•
MRI demonstrates the anatomical configurations and relationships to
other structures that can facilitate surgical planning. Moreover, CT
and MRI have an important role in postoperative follow-up.
15 What are the principles of assessing hypoplastic left
heart syndrome with radiological imaging?
Ultrasound can detect hypoplastic left heart syndrome (HLHS)
•
during prenatal evaluation, especially after week 22 of the pregnancy,
when the ventricular size difference becomes more apparent. In the
postnatal period, echocardiography can confirm the diagnosis.
CMR can be used in the decision making after the initial Norwood
•
procedure to determine whether the patient is suitable for a Glenn
and subsequent Fontan procedure. CMR can precisely delineate the
ventricular size and function, pulmonary arteries and neo-aorta.
CT can be performed before and after the first step of the Norwood
•
procedure to detect any associated anomalies, sizing of neo-aorta,
biventricular size and pulmonary arteries.
197
16 What is the role of radiological imaging in the
assessment of the proximal aortic pathology?
Three-dimensional imaging should be incorporated along with 2D
•
echocardiography in the detection and monitoring of the aortic root
and ascending aorta in connective tissue disorders, such as Marfan
syndrome, Ehlers-Danlos and Loeys-Dietz syndrome, or anomalies,
such as bicuspid aortic valve with concomitant aortic root dilatation.
CTA is the most precise technique for the measurement of aortic
•
diameter.
MRI is the preferred method in follow-up, especially in the young
•
population. Non-contrast 3D SSFP can be used to measure the
aortic root by incorporating multiplanar reconstruction. SSFP cine
images of the aorta can also be used for measurement. Adding CMR
cine images and flow velocity mapping allows the assessment of
concomitant valve disease, such as mitral valve prolapse in Marfan
syndrome, and aortic valve regurgitation in patients with bicuspid
aortic valve.
198
Key Questions in CONGENITAL CARDIAC SURGERY
17 What are the principles of assessing Ebstein’s anomaly
with radiological imaging?
Chest radiography in a severe form of Ebstein’s valve may
•
demonstrate cardiomegaly, a narrow aortic pedicle and decreased
pulmonary vascular markings.
Both CT and MRI can be used to demonstrate the characteristic
•
findings in Ebstein’s anomaly, including the apical displacement of
the septal or posterior tricuspid valve leaflet, atrialised right ventricle,
and severe right atrial enlargement (Figure 25). They also delineate
associated anomalies such as ASD, pulmonary valve stenosis,
subaortic stenosis or aortic coarctation.
AB
RV
RA
RA
CD
RA
Figure 25. Radiological imaging of Ebstein’s anomaly characterised by
apical displacement of the septal tricuspid valve leaflet (arrow), atrialised
right ventricular (RV) and severe right atrial (RA) enlargement on: A) axial
computed tomography; and B) and C) axial steady-state free precession
magnetic resonance imaging; D) sail-like anterior tricuspid leaflet in a fourchamber steady-state free precession magnetic resonance image.
5 Congenital cardiac imaging
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MRI is very useful in the follow-up of patients with Ebstein’s
•
anomaly, as it provides accurate quantitative measurements of the
right ventricular size and function, and tricuspid regurgitation
severity.
MRI also enables detection of any shunt and its haemodynamic
•
significance by quantifying the Qp:Qs ratio. In late gadolinium
enhancement images, fibrotic changes in the atrialised ventricle
can also be identified. CMR is particularly useful in assessing left
ventricular non-compaction (LVNC) cardiomyopathy that has been
reported and associated with Ebstein anomaly.
CMR can also be used in the postoperative surveillance of RV
•
function and repaired (cone) or replaced tricuspid valve.
CT can be helpful in patients with poor echocardiographical
•
acoustic windows for visualising the RV and when MRI is
challenging because of the lack of capability to hold breath. RV
function can be quantified on CT with retrospective gating but at
the cost of increased radiation.
199
18 What are the principles of imaging for planning and
follow-up of transcatheter procedures?
Echocardiography and CT are used to identify a patient’s suitability
•
and feasibility for transcatheter cardiovascular procedures (Figure
26).
Application of non-invasive imaging has significantly improved
•
procedure safety, such as by identification of the correct device
size and by avoiding injury to adjacent structures.
CT is used to evaluate the adequacy and patency of arterial and
•
venous access, and to identify related complications.
Echocardiography, CT and positron emission tomography (PET)
•
are used to identify device infection and its source.
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