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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3737_Библиотеки_им_академика_М_И_Перельмана
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Multimodality Imaging ofRight Ventricular Outow Tract Disease inAdults withCongenital Heart Disease
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139
tension. Historically as neonates grew and the
PAs increased to sufcient size, “complete”
repair became possible. This procedure generally
includes patch repair of the VSD, resection of the
RVOT obstruction, and occasional PA augmentation [4, 6]. Current trends are toward early repair
with valve-sparing techniques and a general
avoidance of palliative shunting.
The initial technique of “complete” repair
included resection of as much tissue as necessary
for full relief of RVOT obstruction. RVOT augmentation was then required with a transannular
patch. The latter resulted in varying degrees of
pulmonic insufciency, which generally
increased over time as the RV and RVOT remodeled. Longstanding and signicant pulmonic
regurgitation (PR) can lead to RV failure and is a
signicant source of morbidity and mortality [4,
5]. In the absence of severe pulmonary annular
hypoplasia, the surgical approach today is transatrial/trans-pulmonary incision with closure of
VSD and relief of RVOT obstruction using valve
sparing techniques, recognizing residual obstruction is better tolerated (with regression over time)
than regurgitation. In other variants of TOF
where the pulmonary arterial tree is hypoplastic,
valved RV-PA conduits can be used to provide
adequate antegrade ow [2, 3, 6]. Patients with
pulmonic atresia and intact ventricular septum
have a severely atretic pulmonic valve with circulation dependent on the presence of a patent ductus arteriosus and/or an interatrial communication.
These patients also have variable degrees of right
ventricular and tricuspid valve hypoplasia that
complicate the pursuit of complete biventricular
repair. During infancy, palliation centers around
promotion of pulmonary blood ow. This is
achieved via prostaglandin infusions and interventions such as surgical shunts and ductal stents.
In the absence of right ventricular dependent
coronary ow, decompression is achieved by pulmonary valvotomy with or without transannular
repair. For patients who have right ventricular
dependent coronary ow or if the right ventricle
remains hypoplastic and diminutive despite
decompression, a single ventricle surgical repair
strategy is often employed. In patients with a sufcient RV and tricuspid valve, the RVOT is
reconstructed using a transannular patch, the
ASD is closed, and valvotomy is performed.
These patients, similar to TOF repaired by transannular patch, undergo repeated PV interventions
[2, 3].
In infants with critical isolated pulmonic stenosis (PS), cyanosis is common as the ductus
arteriosus begins to close in the rst few hours of
life and elevated right sided pressures result in
right-to-left shunting across the foramen ovale.
The anatomy is often described as a dome-shaped
valve with commissural fusion, or a dysplastic
valve with thickened leaets [2, 7]. For those
infants with severe symptoms, a peak gradient
≥40 mmHg and ductal dependency, catheter
based valvuloplasty provides a bridge to denitive surgical intervention later in infancy. While
valvuloplasty works well for domed valves, it is
less successful for thickened, dysplastic valves,
where surgical intervention is usually required
[8]. Surgical technique is dependent on the degree
of annular hypoplasia. In the absence of severe
annular hypoplasia, incision of the commissures
may increase valve area; while severe annular
hypoplasia and supravalvular stenosis require
techniques used in TOF repair, including transannular patching and PA augmentation [2, 6].
Despite good durability, complications like those
seen in TOF occur, [5] including RVOT obstruction, PR, and endocarditis.
For patients with PS, follow-up with Adult
Congenital Heart Disease (ACHD) providers
depends on symptoms and clinical status, with
imaging performed as frequently as every
1–5 years depending on lesion severity [9].
Severity in PS is graded similarly to aortic stenosis. Mild PS is identied by a peak velocity <3 m/s and severe PS with a peak
velocity >4 m/s. Indications for intervention
include at least moderate PS (≥3 m/s velocity)
with exertional limitation, cyanosis, or heart failure. RVOT obstruction uses the same velocity
criteria and intervention is indicated for patients
with at least moderate obstruction of a RV-PA
conduit if there is a decline in functional status or
increased burden of arrhythmias [9, 10]. For
patients with PR, either after management of isolated PS or after repair of TOF, intervention is
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T. Spates and R. A. Krasuski
recommended for at least moderate PR and associated symptoms. If the patient is sedentary, exercise testing can be helpful to uncover functional
limitation. Quantitative assessments with imaging can identify a Class IIa indication for valve
replacement. Moderate PR associated with signicant RV dilation by cardiac magnetic resonance imaging (cMRI) volumes, RV dysfunction
or LV dysfunction, or associated moderate or
namic assessment, close monitoring of radiation
exposure is essential for young adults with
CHD. Given concerns regarding lifetime radiation exposure, alternative imaging modalities
should be considered whenever possible. cMRI is
ideal for patients who require close monitoring of
ventricular volumes given the lack of radiation
exposure; thereby justifying its Class I recommendation [9–11, 14].
greater tricuspid regurgitation (TR) are
indications for PV replacement, as is RVOT
obstruction with RVSP ≥2/3 systemic pressure.
If there are no additional pathologies that require
surgical intervention, a transcatheter approach
should be considered [9, 10].
In patients with extensive surgical histories
and the presence of bioprosthetic material, limiting the risk of systemic infection is paramount.
The ACC/AHA Guidelines recommend antibiotic prophylaxis in patients with prosthetic
valves, a prior history of endocarditis, the presence residual shunts at sites of prior repair, history of uncorrected cyanotic heart disease, or
recent intervention using prosthetic material in
the last 6 months. Should patients present with
concerns for systemic infections, blood cultures
and dedicated cardiac imaging are required to
evaluate for the presence and extent of endocarditis [9, 11].
Surveillance for long-term complications
from RVOT pathology is necessary and often utilizes a multi-modality approach.
Echocardiography is the rst-line tool used to
delineate anatomy as justied by appropriate use
transthoracic, transesophageal, and ICE. Chest
wall imaging is the main modality used for surveillance in repaired CHD, but can be limited by
poor imaging windows (body habitus and lung
disease) and artifact from prosthetic material.
Sedated intraprocedural transesophageal echo or
ICE can eliminate such artifacts. RV dysfunction
is dened by echo as a fractional area change
<35%, or diminished tricuspid annular excursion
as measured by TAPSE and S′ velocity [12]. For
patients with prior pulmonic interventions or
prosthetic PVs, visualization of the RVOT or PV
can be challenging. While grading obstruction
and stenosis of the RVOT or PV is more direct,
quantitative assessment of PR is more challenging. Severity of PR is delineated by jet width, jet
density, regurgitant volume and regurgitant fraction. Mild PR is characterized by a regurgitant jet
width<20% of annular diameter, an incomplete
continuous wave Doppler envelope and a regurgitant fraction <20%. Severe PR is characterized
by jet width>40% of annular diameter, dense and
complete continuous wave Doppler envelope and
regurgitant fraction >40% [12, 15].
criteria and is routinely used for the evaluation of
structural complications [12, 13]. The AHA/ACC
Guidelines recommend the use of additional
imaging for more quantitative ventricular assessment or a detailed reconstruction of vascular
anatomy [10, 14]. Other imaging modalities
include cMRI, CCT, and right heart catheterization (RHC), which can provide hemodynamic,
uoroscopic and intracardiac echo (ICE) evaluation. While imaging modalities like CCT and
RHC can provide anatomical detail and hemody-
vide vascular, volumetric and structural detail.
An advantage of CCT is shorter scan times than
cMRI, at the price of ionizing radiation exposure
and the need for contrast media administration.
While it is possible to create anatomic three-
dimensional reconstructions using either CCT or
cMRI, CCT is generally favored due to higher
spatial resolution. Reconstructions facilitate pre-
procedural planning, including the selection of
appropriate devices [11, 14, 16] (Fig.1).
Two-dimensional echocardiography includes
Multi-detector CCT with ECG gating can pro-
Multimodality Imaging ofRight Ventricular Outow Tract Disease inAdults withCongenital Heart Disease
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141
Fig. 1 Cardiac CT of our patient demonstrating a multi-planar reconstruction with short axis, four chamber and 2
chamber view of the left ventricle with volume rendered image
cMRI has emerged as an essential component
for the follow-up of patients with congenital
heart diseases and is especially valuable in
assessing the RV, RVOT and PV.The AHA/ACC
Guidelines give a Class I recommendation for
cMRI if RV volumes are required to guide management. Quantitative assessment of RVEF can
be performed using steady state free precession
(SSFP) cine imaging and volumetric calculation,
[5] with RV dysfunction dened as an RVEF
<50%. Ventricular volumes are indexed to body
surface area. Thresholds for intervention in pulmonic regurgitation include an RVEDVI
≥160mL/m2, RVESVI ≥80mL/m2, or RVEDV
≥2 × LVEDV [9, 10, 14, 17] (Figs.2, 3 and 4).
Quantication of PS and PR severity can be
performed by velocity encoding phase contrast
imaging. This sequence assesses the velocity of
protons in a particular region in relation to a
technician- specied velocity. If that region of
interest aliases, it indicates the velocity exceeds
that preset parameter. This same modality can not
only interrogate stenoses, but also quantify regurgitation by assessing ow during systole and
diastole. Velocity encoded imaging is most accurate when interrogating laminar ow.
Occasionally velocities can signicantly overestimate or underestimate gradients when the
regurgitation is eccentric or turbulent. Regurgitant
lesions can also be quantied using the volumetric assessments for LV and RV stroke volumes in
the absence of any confounding regurgitant
lesions [14].
Each imaging modality has inherent limitations. Thus, the use of multiple modalities can
provide more complete assessment of anatomy
and hemodynamics, more accurately guiding
clinical management (Fig.5).
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T. Spates and R. A. Krasuski
Fig. 2 Short axis slices of the ventricles used for visual assessment and volumetric quantication of ventricular function using SSFP cine imaging
Multimodality Imaging ofRight Ventricular Outow Tract Disease inAdults withCongenital Heart Disease
https://t.me/med1917
Fig. 3 Dedicated views
of the LV using SSFP
cine imaging
143
Fig. 4 Dedicated views of the RV using SSFP cine imaging
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Fig. 5 Adapted table of
appropriate use criteria
for multimodality
imaging for specic
congenital anatomies
[13]
T. Spates and R. A. Krasuski
Diagnosis andPre-procedural
Evaluation
The patient had been followed in the Adult
Congenital Heart Disease Clinic at ~6-month
intervals, with his sole complaint being intermittent lower extremity edema that usually responded
well to diuresis. Routine echocardiography
revealed grossly normal biventricular function
with mild TR, trivial PR and moderate PS with a
peak velocity of 3.1m/s (Fig.6).
The patient returned to clinic frequently over
the course of the next year with complaints of
increasing lower extremity edema, shortness of
breath, and progressively lower oxygen saturation. His diuretic regimen was increased frequently with intermittent improvement. Given
his progressive symptoms, a cMRI was
performed.
Calculated LVEF was 67% and RVEF was
45%, with evidence of RV pressure and volume
overload. Imaging further demonstrated regional
akinesis of the infundibular region with adherence
to the sternum. The RVOT patch was stable and
there was no evidence of residual VSD.Moderate
PR was present, although the regurgitant fraction
measured only 19%. The regurgitant jet was turbulent in appearance, with peak velocity measuring 3.2m/s, consistent with moderate PS.Because
the data were largely unchanged from his prior
study, routine follow- up at 6months was planned
(Figs.7 and 8).
At follow-up ~6months later, the patient was
profoundly dyspneic and required direct admission to the cardiovascular intensive care unit for
hypoxic respiratory failure, volume overload, and
systemic hypotension. A RHC was performed
and revealed a transpulmonary peak-to-peak gradient of 31 mmHg at the level of the valve
(Fig.9).
Aggressive diuresis was continued and the
need for PV intervention were discussed.
Multimodality Imaging ofRight Ventricular Outow Tract Disease inAdults withCongenital Heart Disease
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145
Fig. 6 Peak velocity in the RVOT of 3.1m/s measured at the level of the PV
Fig. 7 Volumetric
assessment to determine
LV volumes and
function, which were
normal. Note the RV
stroke volume exceeds
that of the LV, consistent
with a regurgitant valve
and increased RVEDV
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Fig. 8 Velocity encoded
phase contrast imaging
at the level of main PA
revealing a peak velocity
of 3.2m/s. Note the
reversal of ow below
the baseline, which
represents signicant
regurgitation
T. Spates and R. A. Krasuski
Multimodality Imaging ofRight Ventricular Outow Tract Disease inAdults withCongenital Heart Disease
https://t.me/med1917
Fig. 9 RHC
demonstrates
a~31mmHg peak-topeak gradient across the
pulmonic valve and
elevated pulmonary
capillary wedge pressure
consistent with at least
moderate PS and
concomitant left
ventricular diastolic
dysfunction. Of note, the
patient was given
moderate sedation,
which could reduce
cardiac output and lead
to gradient
underestimation
147
Heart Team Approach
andDiscussion
Based on admission for decompensated HF and
evidence of RV dysfunction with at least moderate PS and/or PR, the patient met a Class I indication for PV intervention based on 2018 AHA/
ACC Guidelines for Management of ACHD [9,
10] (Figs.10 and 11).
Surgical and transcatheter valve replacement
options were considered with the patient. Given
his respiratory limitation (chronic hypercarbia
and hypoxemia), the proximity of RV free wall to
sternum, and his advanced clinical status, the
decision was made to pursue transcatheter valve
implantation.
There are two types of transcatheter pulmonic
prostheses currently available, balloon expand-
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Fig. 10 Modied table
regarding general
indications for
intervention in PR in
repaired TOF [2, 9, 10]
Fig. 11 Modied table regarding strength of recommendations for intervention in repaired TOF [2, 9, 10, 17]
T. Spates and R. A. Krasuski
able and self-expanding platforms/valves. Balloon
expandable valves were rst developed for delivery into conduits and bioprostheses, which serve
as ideal landing zones. The two FDA approved
balloon expandable valves are the Melody
(Medtronic, Minneapolis, MN) and Sapien
(Edwards Lifesciences, Irvine, VA) valves. These
valves are generally not able to be delivered into
patch-repaired outow tracts as they are limited in
size by the balloon expandible system, with the
Melody Valve sized from 18–22 mm and the
Sapien Valve from 20–29mm. Prior to implantation, proper sizing is essential, as is intraprocedural balloon compression testing to ensure no
distortion of the aortic or coronary anatomy [18].
Self-expanding devices include the Harmony
Valve (Medtronic, Minneapolis, MN) and the
Alterra Adaptive Prestent (Edwards Lifesciences,
Irvine, VA), the latter of which is used in concert
with the 29 mm Sapien S3 Valve (Edwards
Lifesciences, Irvine, VA). These devices can
expand to much larger sizes without risk for coronary or aortic compression. Neither device by
design, however, treats stenosis. For both devices,
pre-procedural RVOT assessment is required using
a specialized CT scan shared with the respective
company to assess candidacy, model the valve
implant and determine the ideal landing zone [18].
Intra-procedural Imaging
The patient underwent cardiac catheterization
with a plan for RVOT augmentation via stenting
followed by placement of a transcatheter pulmonic valve.
Prior to proceeding, the operator ensures
absence of coronary artery or aortic compression
by inating a high-pressure balloon across the
RVOT/MPA during aortography or selective coronary angiography.
With no coronary artery compression or aortic
deformation, the operators proceeded with stent
placement [14]. After two stents were deployed
(to provide increased radial strength), free PR
was present as expected. The stent was further
expanded by post-dilatation to ensure an adequately sized delivery zone for the transcatheter
valve (Figs.12 and 13).
A 23mm Sapien S3 valve was then delivered
into the pulmonic position. Mild residual narrowing was still present at the completion of the case,
secondary to conduit calcication and external
compression, though the transpulmonary gradient was reduced to only 2mmHg (Fig.14).
An echocardiogram was performed postprocedurally and revealed no evidence of stenosis or regurgitation (Fig.15).
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