Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5189_Библиотеки_им_академика_М_И_Перельмана.pdf
274
LA
=−
()
vMR
LAPRAP=
()
+
vIAS
Fig. 21.1 The Bernoulli
principle:The change in
pressure across an
orice can be calculated
by applying the concept
of the conservation of
energy using the
Bernoulli equation
C. Bennett
P
2
P
1
therefore, hemodynamic catheterization may be
necessary for workup. The other cause of
increased upstream velocity may occur in the setting of increased blood ow, such as anemia or
pregnancy, and needs to be taken into consideration as well. An external factor contributing to
the limitations of the equation includes the
accuracy of the Doppler signal, which may be
faint, incomplete, or subject to poor Doppler
alignment. When calculating the right ventricular
systolic pressure (RVSP), there are potential
errors incurred when estimating the right atrial
pressure [6].
Fig. 21.2 This image shows simultaneous catheter measurements of the LA (via a transeptal approach) and LV
and continuous-wave Doppler of mitral regurgitation by
echocardiography. The peak gradient between the LA and
LV by catheter is 87mmHg (black arrow). The peak gradient by echocardiography using the peak velocity of
4.8 m/s (black arrowhead) is 92 mmHg. This demonstrates that the pressure difference between 2 cardiac
chambers by peak catheter measurement is very similar to
the calculated difference by Doppler of the regurgitant
signal (Reproduced with permission from Nishimura RA,
Tajik AJ). Determination of left-sided pressure gradients
by utilizing Doppler aortic and mitral regurgitant signals:
validation by simultaneous dual catheter and Doppler
studies. J Am Coll Cardiol. 1988;11(2):317–21)
and must be applied to the equation to avoid
overestimation of the downstream pressure gradient [5]. However, it is not always feasible to differentiate the velocities at each level, and
Intracardiac Pressures
Left Atrial Pressure
The left atrial pressure (LAP) may be estimated
using the mitral regurgitant velocity, which
occurs during systole, and the known systolic
blood pressure (SBP) because the systolic
blood pressure equals the left ventricular systolic pressure (LVSP) in patients without left
ventricular outow tract obstruction. In other
words, we can use the known SBP and the calculated pressure difference between the LA and
LV to solve for the LAP.It can be arranged as
follows:
PSBP
If an intraatrial shunt is present, then the maximum velocity across that shunt may be used to
calculate the LAP with the addition of the right
atrial pressure (RAP).
4
2
4
2
LV
=−
()
vAR
RVSP
=
()
+
vTR
RVSP
P=
()
+
vVSD
PAEDPRAP=
()
+
vPR
LAP
g=
()
+=
RVSP
g=
()
+=
21 Calculation ofIntracardiac Pressures Using Doppler Flow
275
Left Ventricular End-Diastolic Pressure
The left ventricular end-diastolic pressure
(LVEDP) may be calculated applying the same
principle as with LAP using the end-diastolic
aortic regurgitant velocity during diastole. The
aortic regurgitant velocity represents the pressure
gradient between the left ventricle and the aorta.
In this scenario, the calculated pressure difference between the aorta and LV is subtracted from
the known aortic pressure or diastolic blood
pressure (DBP) to solve for the LVEDP.It can be
arranged as follows:
In addition to the above methods, diastolic tissue Doppler metrics and mitral inow patterns
can be applied to evaluate left ventricular lling
pressure. The mitral inow velocity to mitral tissue Doppler velocity ratio (E/e’) has demonstrated correlation with the end-diastolic lling
pressure measured by left heart catheterization.
EDPDBP
2
4
Right Ventricular Systolic Pressure
RVSP, which occurs during systole, and the right
atrial pressure. The RAP is also estimated and
therefore a potential cause of error in the estimated RVSP.The calculated pressure difference
between the RA and RV and the estimated RAP
are added to solve for the RVSP and are arranged
as follows:
2
If there is a ventricular septal defect present,
then the maximum velocity across that defect
between the LV and RV plus the RAP can also be
used to calculate the RVSP:
In the absence of pulmonary valve stenosis or
other causes of right ventricular outow tract
obstruction, the RVSP equals the pulmonary
4
4
RAP
2
RA
artery systolic pressure. This can be used in the
evaluation of pulmonary hypertension. Pulmonary
regurgitation represents the pressure gradient
between the pulmonary artery and right ventricle
during diastole. Using the end-diastolic pulmonary regurgitant velocity with the addition of the
RAP, the pulmonary artery end-diastolic pressure
(PAEDP) can be calculated as follows:
2
4
Case
Doppler-derived intracardiac pressures correlate
well with pressures obtained by catheterization in
the laboratory. We can noninvasively assess
patient hemodynamics by applying the principles
discussed in this chapter.
A 70-year-old male with advanced cardiac
amyloidosis and severely reduced left ventricular
systolic function presents with severe shortness
of breath. His blood pressure at the time of the
exam is 104/68 mmHg. His echocardiogram
reveals moderate tricuspid regurgitation
(Fig. 21.3a) and a peak tricuspid regurgitant
velocity of 2.3 m/s (Fig. 21.3b). A subcostal
4-chamber view focused on the intraatrial septum
with color Doppler demonstrates left-to-right
ow across a patent foramen ovale with a peak
velocity of 2.0m/s across the septum (Fig.21.3c,
d). A subcostal view of the inferior vena cava
demonstrates a diameter of 29mm and does not
collapse. The interpreter estimates a RAP of
15 mmHg based on these ndings. Using the
equations reviewed in this chapter, we can calculate both the LAP and RVSP here:
2
4201531
Based on these ndings, the provider increased
the patient’s diuretic regimen and afterload
reduction therapy with signicant improvement
in his symptoms.
.
2
4231536
.
mmH
mmH
276
C. Bennett
a
b
d
Fig. 21.3 The apical 4-chamber view focused on the
right ventricle with color Doppler demonstrating moderate tricuspid regurgitation (a). The peak TR velocity is
2.3m/s (b). A PFO is seen with left-to-right ow by color
c
Doppler (c) with a peak Doppler velocity of 2.0m/s (d).
The IVC is dilated with <50% collapse correlating with an
estimated RAP of 10–20mmHg
Summary Points
• The assessment of intracardiac pressures and
valve stenoses by echocardiography has utilized ultrasound Doppler signals.
• Calculations apply the Bernoulli principle,
which states that in the streamline ow of
uid, the sum of all forms of energy along that
path are equal.
• Intracardiac pressures are obtained using the
measured pressure gradient and a known pressure of one cardiac chamber.
21 Calculation ofIntracardiac Pressures Using Doppler Flow
277
References
1. Hatle L. Noninvasive measurements of intracardiac
blood ow velocities with Doppler ultrasound. Acta
Med Scand. 1987;221(2):133–6.
2. Yock PG, Popp RL.Noninvasive evaluation of intracardiac pressures using Doppler ultrasound: a case
study of panvalvular regurgitation. Clin Cardiol.
1985;8(11):565–71.
3. Nishimura RA, Miller FA Jr, Callahan MJ, Benassi
RC, Seward JB, Tajik AJ.Doppler echocardiography:
theory, instrumentation, technique, and application.
Mayo Clin Proc. 1985;60(5):321–43.
4. Nishimura RA, Tajik AJ. Determination of left-sided
pressure gradients by utilizing Doppler aortic and
mitral regurgitant signals: validation by simultaneous
dual catheter and Doppler studies. J Am Coll Cardiol.
1988;11(2):317–21.
5. Scantlebury DC, Geske JB, Nishimura RA.Limitations
of Doppler echocardiography in the evaluation of serial
stenoses. Circ Cardiovasc Imaging. 2013;6(5):850–2.
6. Finkelhor RS, Lewis SA, Pillai D. Limitations and
strengths of doppler/echo pulmonary artery systolic
pressure-right heart catheterization correlations:
a systematic literature review. Echocardiography.
2015;32(1):10–8.
Prosthetic Valves
GloriaA.Ayuba andVeraRigolin
22
Abbreviations
2D Two-dimensional
3D Three-dimensional
AT Acceleration time
CW Continuous wave Doppler
DI Dimensionless index
EOA Effective orice area
PLAX Parasternal long axis
PSAX Parasternal short axis
PW Pulsed wave Doppler
TEE Transesophageal echocardiography
TTE Transthoracic echocardiography
Supplementary Information The online version contains supplementary material available at https://doi.
org/10.1007/978- 3- 031- 80038- 2_22.
G. A. Ayuba
Department of Medicine/Division of Cardiology, UT
Southwestern, Dallas, USA
e-mail: gloria.ayuba@nm.org
V. Rigolin (*)
Northwestern University Feinberg School
of Medicine, Chicago, IL, USA
Department of Medicine, Bluhm Cardiovascular
Institute, Northwestern University Feinberg
School of Medicine, Chicago, IL, USA
e-mail: vrigolin@nm.org
General Imaging Principles
Echocardiography is the primary imaging
modality used to evaluate prosthetic heart valves.
A complete echocardiographic study in patients
with prosthetic valves includes assessment of
chamber sizes, systolic and diastolic ventricular
function, and wall thickness in addition to evaluation of the prosthesis itself using 2D, Doppler,
and 3D imaging techniques if available [1, 2].
Prosthetic valves have varying ow proles
depending on the valve type and size and have
some degree of obstruction inherent to their
design compared to normal native valves. So, it is
important to obtain and report clinical information, including type and size of prosthetic valve,
surgery date, blood pressure, heart rate, age,
height, weight, and body surface area when available to allow for appropriate and accurate assessment and comprehensive reporting.
Consulting published guidelines and standards
Data on normal hemodynamics of different prosthetic valves is critical to determining if the function of a specic prosthetic valve is normal [2].
Baseline prosthetic structure and function should
be evaluated 1–3months after the implantation to
allow for normalization of hemodynamics and loading conditions [1]. This provides a baseline to which
subsequent imaging may be compared for change.
Echo assessment should include evaluation
of structural features such as mobility of the
leaets and/or sewing ring, interrogating for
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine, https://doi.org/10.1007/978-3-031-80038-2_22
279
280
a
Fig. 22.1 Posterior
acoustic shadow artifact
(arrow) seen on TTE
created by the
bioprosthetic aortic
valve (panel a). There is
adequate visualization of
posterior region of the
prosthesis when imaged
using TEE.However,
note the anterior shadow
artifact on the TEE
image (arrow) (Panel b)
G. A. Ayuba and V. Rigolin
b
complications including valve thrombus, pannus in growth, vegetations, abscesses, or stulas, and hemodynamic assessment including
evaluation of peak velocity, peak/mean gradients, effective orice area, valve regurgitation,
and stroke volume.
Adequate echocardiographic evaluation
using multiple windows by transthoracic echocardiography (TTE) is necessary and, if suboptimal, may require the use of transesophageal
echocardiography (TEE) for better visualization
given better axial resolution, particularly in the
evaluation of prosthesis-associated complications
such as endocarditis, thrombus or pannus ingrowth,
and regurgitation, where visualization may be limited by acoustic shadowing or reverberation.
TTE and TEE can be complementary in aortic
prosthetic valve assessment where shadowing
and reverberations limit adequate assessment of
the posterior and anterior aspects of the valve,
respectively, and so assessment with both modalities may be needed for adequate visualization of
the entire valve for complications such as perivalvular leaks [2] (Fig.22.1).
22 Prosthetic Valves
Fig. 22.2 Linear
measurements in the
parasternal long axis
view of interventricular
septal thickness, LV end
diastolic internal
dimension and posterior
wall thickness are
standard echo
measurements for all
patients with valvular
heart disease. Although
not shown in this image,
LV end systolic internal
dimension is also a
standard measurement
281
2D Imaging
2D imaging assessment by TTE or TEE should
include evaluation of chamber sizes, wall thickness, biventricular function (Figs.22.2 and 22.3),
prosthetic valve position, leaet mobility, and sewing ring appearance during the entire cardiac cycle.
3D Imaging
3D Echo allows for visualization and assessment
of the complex geometric shape of the heart and
visualization of prosthetic valves from any
perspective.
It is useful to identify the mechanisms of prosthetic dysfunction and can help localize pathology and guide transcatheter-based interventions
in prosthetic valve disease. Left ventricular (LV)
volumes and LV ejection fraction measurements
are also more reproducible when calculated using
3D echo rather than 2D echo.
Doppler Evaluation
Doppler assessment of prosthetic valves is
useful in the identication and evaluation of
prosthetic valve dysfunction. Color Doppler
identies regurgitant lesions and areas of turbulent ow. Spectral Doppler (with pulsed
wave (PW) and continuous wave (CW)) measures the peak velocity across the valve, peak/
mean gradients, acceleration time (AT) (in the
evaluation of aortic prosthesis), dimensionless
index (DI), and pressure half time (of regurgitant aortic jets or stenotic mitral prostheses)
and provides the data to calculate effective orice area (EOA).
The peak velocity and gradients across a valve
are determined by the valve type, valve size, and
ow rate, and obtaining information on the
implanted prosthesis allows appropriate contextual interpretation.
The peak gradient across prosthetic valves is
calculated by the simplied Bernoulli equation [2].
Peak pressure gradient = 4 × V 2 [2], where
V=peak velocity of jet (m/s). The mean gradient
is the average gradient across the valve during
systole or diastole, depending on the valve. This
is obtained by averaging the instantaneous gradients over the ejection period and is usually calculated by the ultrasound system measurement
package from the traced Doppler velocity curve.
Stroke volume is calculated by multiplying the
velocity time integral (VTI) of the left ventricular
outow tract (LVOT) obtained with PW Doppler
by the cross-sectional area (CSA) of the LVOT.
282
S
lvot lvot
=×
EO
pv=
G. A. Ayuba and V. Rigolin
Fig. 22.3 2D LV end-diastolic and end-systolic volumes are acquired from the 4 and 2 chamber apical views. LV ejection fraction is then calculated using the Simpson’s biplane method using the traced volumes
VVTI CSA
Role ofTEE
TEE should be considered when there is subopti-
The effective orice area (EOA) of a prosthe-
sis is calculated using the continuity equation:
AStroke volumeVTI
/
The dimensionless index (DI) for prosthetic
AV assessment is the ratio of the LVOT VTI/AV
VTI, and the DI of a mitral valve prosthesis is
derived from the ratio of MV VTI/LVOT
VTI.Note that the continuity equation is the preferred method to calculate EOA in both AV and
MV prostheses. Although pressure half-time is
useful to determine the presence of prosthetic
MV dysfunction, it should not be used to calculate EOA.
mal or non-diagnostic assessment of prosthetic
valves by TTE, particularly when there is a concern for dysfunction. It is useful in the assessment
of the etiology and mechanism of prosthetic stenosis and regurgitation and is used in transcatheterbased intervention planning and management.
TEE should be used in the assessment of complications of infective endocarditis or if there is a
clinical concern for endocardial lead involvement. It may also be considered for evaluation of
patients with prosthetic valves with persistent
fever of unknown etiology or patients with staph
aureus bacteremia without a known source to rule
out infective endocarditis [1].
de
ab
22 Prosthetic Valves
283
Overview ofTypes ofProsthetic
Valves
Over the last six decades, prosthetic valves have
been designed with the goal of having characteristics that are like native valves, including
excellent durability, hemodynamics, and low
thrombogenicity. At this time, no perfect valve
exists, and all prosthetic valves have some
inherent obstruction compared to normal native
valves.
Prosthetic valves are broadly grouped into
mechanical or bioprosthetic valves.
There are several makes and models of bioprosthetic valves. Some are made to be implanted
surgically and can be stented or stentless. Others
are implanted percutaneously (Fig.22.4).
Mechanical valves consist of bileaet, single
tilting disc, or caged-ball valves. The latter is no
longer implanted but can be seen in some patients
who underwent surgery prior to 2007 (Fig.22.5).
The choice of prosthetic types in patients is
determined by several factors, including patient
age, preference, valve size, expected hemodynamics, risks of long-term anticoagulation with
mechanical valves, and limited durability requiring repeat interventions in the case of bioprosthetic valves.
Physiologic Regurgitation
andMicrocavitations
Mechanical valves have a built-in physiologic
regurgitation that is important to recognize and be
able to differentiate from pathologic regurgitation.
Bileaet mechanical valves have two semilunar
disks with opening angles from 75 to 90 degrees
c
Fig. 22.4 The common types of commercially available
bioprosthetic valves are shown. (a) Percutaneous balloon
expandable bioprosthesis (Edwards Sapien); (b
expandable percutaneous bioprosthesis (Medtronic Evolut
) self-
R); (c) stented pericardial bioprosthesis (Perimount
Magna Ease); (d) stented porcine bioprosthesis (Medtronic
Mosaic); (e) stentless porcine bioprosthesis (Medtronic
Freestyle)
284
G. A. Ayuba and V. Rigolin
ab c
Fig. 22.5 The common types of commercially available mechanical valves are shown. (a) Bileaet mechanical valve
(St Jude Medical Regent); (b) Single leaet mechanical valve (Medtronic Hall); (c) caged ball valve (Starr-Edwards)
Fig. 22.6 TEE image
showing
microcavitations in left
atrium (arrow) in patient
with a mechanical
bileaet prosthetic valve
in the mitral position
with three orices noted when the valve opens and
typically three built-in washing jets (physiologic
regurgitation) when it closes, which is thought to
prevent thrombi at sites of stasis on the valve [2,
3]. Monoleaet valves have a single disk attached
to a metal strut with an opening angle from 60 to
80 degrees with two orices noted when it opens
and a single midline built-in physiologic regurgitation when it closes [3]. The ball-shaped occluder
in caged ball valves, such as the Star Edwards
valve is difcult to visualize on echo, but closure
of the valve, creates a small closing volume.
Microcavitations may be seen in the ventricle
or atrium and appear as echo-bright bubbles that
occur during the opening and closing of a
mechanical valve (Figs. 22.6, 22.7 with corresponding Video 22.1). This occurs because of the
vaporization of blood due to a rapid drop in pressure at the site closure of the sewing ring and
prosthetic occluder [4]. These gaseous microbubbles are seen with mechanical valves and are
more common in the mitral position and usually
do not reect any pathology but may be misdiagnosed as vegetation.