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Fig. 3.15 Anatomic descriptors and spatial coordinates using 2D and 3D TEE for mitral valve interventions. 2D TEE imaging can be used to define anterior-posterior dimension in the standard long-axis view
(panel A, multiplane angle 120 to 150 degrees), whereas the four-chamber view (panel B, multiplane angle
0 degrees) is useful to define objects in the medial-lateral dimension. The LAA is another useful anterolateral
landmark typically seen in the commissural view (panel C, multiplane angle 60 to 80 degrees). 3D TEE with
an en face view of the MV from the perspective of the LA (surgeon’s view) provides a panoramic view of the
LA and simultaneous localization in the anterior-posterior and medial-lateral dimensions (panel D). AV, Aortic
valve; LA, left atrium; LAA, left atrial appendage; LSPV, left superior pulmonary vein; LV , left ventricle; MV,
mitral valve.
to guide the interventional cardiologist as they probe for the PVR defect (Fig. 3.16). In some
cases the defect may be visible on the surface-rendered 3D image itself, but in the case of small
regurgitant lesions they may not be visible on the surface-rendered image. For smaller defects,
toggling between 3D color Doppler images, which show the regurgitant jet, and non–color
Doppler 3D image can be helpful for better localization.
Potential complications include inadvertent insertion of the wire or catheter through the
prosthetic valve orifice rather than the PVR defect or interference with the normal disk motion
in mechanical prostheses. Interference with disk motion is readily identified by both 2D and 3D
TEE. An implanted plug can potentially prevent a disk from opening during diastole, resulting
in acute mitral stenosis, or prevent adequate closure of the valve during systole, resulting in acute
MR. Additional monitoring is necessary to evaluate for cardiac perforation and tamponade,
worsening valve dehiscence and regurgitation, device embolization, and device-related thrombus
formation.
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Fig. 3.16 Live 3D TEE guidance of mitral PVR closure. Live 3D TEE images show the steerable guide
catheter (blue arrow) crossing the atrial septum (FO) and cannulating the PVR defect. In this image, the
proximal disk of the vascular plug can be seen deployed on the atrial side of the PVR defect (red arrow). AV,
Aortic valve; FO, fossa ovalis; LAA, left atrial appendage; MV, mitral valve.
After deployment of the plug(s), a critical component of the evaluation is determining the
severity of residual PVR. Residual regurgitant jets can be difficult to quantify, given that they are
frequently fragmented, eccentric, and assessment may be limited by acoustic shadowing. Whenever possible, residual regurgitation should be assessed at a blood pressure that is similar to the
patient’s normal physiologic blood pressure and ideally similar to the preprocedure blood pressure
because of the load-dependent nature of regurgitant lesions. Assessment with color flow Doppler
imaging from multiple angles and with color Doppler 3D TEE are critical for visual assessment.
Additionally, changes in pulmonary vein flow pre- and postimplantation can be very helpful to
gauge the hemodynamic improvement in MR postprocedure. Systolic antegrade pulmonary vein
flow that improves or normalizes postprocedure strongly supports improvement in MR. Residual
atrioseptal defects are common at the site of TSP, but shunting is typically left to right. Significant right-to-left shunting and/or need for atrioseptal defect closure is uncommon.
Transcatheter Edge-to-Edge Mitral Repair
TMVR is a currently available transcatheter technique based on the surgical Alfieri technique
whereby the anterior and posterior mitral leaflets are opposed together at the site of MR, creating
a double-orifice mitral valve and decreasing the severity of regurgitation.
(Abbott Vascular, Santa Clara, CA) relies on femoral venous access and a TSP to gain access to
the left atrium for percutaneous repair of the mitral valve.
PREPROCEDURE IMAGING
The preprocedure assessment should include a detailed 2D and 3D echocardiographic assessment
of mitral valve anatomy, quantification of the severity of MR, interrogation of the atrial septum
before TSP, an assessment of cardiac size and function, and screening for preexisting pericardial
effusion, among others. TEE is an essential tool to optimize patient selection before a planned
11
The MitraClip system
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TMVR. The assessment of MR severity requires a multiparametric, integrated approach. A
comprehensive assessment includes a visual assessment of the area of the regurgitant jet by color
Doppler imaging, the jet vena contracta diameter, an assessment of pulmonary vein flow, and
quantitative echocardiography to calculate the regurgitant orifice area and regurgitant volume.
The presence of a flail scallop or visible noncoaptation of the leaflets by 2DE are also considered
specific signs for severe MR.
There have been a number of proposed mitral valve anatomic criteria for patient selection, but
there are limited data supporting their utility. Initial studies evaluating the MitraClip system
excluded patients with a flail width .15 mm and a flail gap .10 mm (Fig. 3.17),
11
but there are
little data supporting these cutoffs in clinical practice. In our practice we have found that the
presence of a flail scallop and/or a regurgitant jet that is confined to a single scallop is associated
with optimal MR reduction and favorable reduction in left atrial pressure postprocedure.
12
Fig. 3.17 Preprocedure anatomic imaging for TMVR. Flail gap (A) and flail width (B) are typically measured
in patients with flail leaflet before TMVR with edge-to-edge repair. Flail width is defined as the medial-lateral
distance of the flail segment along the affected mitral leaflet. In our practice we typically measure flail width
in the midesophageal bicommissural view (A, multiplane angle 60 to 80 degrees, red arrow), although alternative views may be necessary for flail scallops that arise closely to the valve commissures. Flail gap, defined
as the largest distance or gap between anterior and posterior leaflets, is shown measured at a multiplane
angle of 0 degrees (B, blue arrow), but alternative views may be needed to optimize this measurement
depending on the location of the flail scallop. 3D TEE with a surgeon’s view of the LA (C) often more precisely
defines the location and extent of the flail scallop. In a patient with secondary mitral regurgitation, coaptation
length .2 mm is considered adequate before edge-to-edge repair (D, yellow arrow). AML, Anterior mitral
leaflet; AV, aortic valve; LA, left atrium; LV , left ventricle; PML, posterior mitral leaflet.
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An absence of calcium at the clip-grasping location is also important to be able to adequately close
the clip during grasping. In patients with secondary MR, coaptation length .2 mm is considered
adequate for attempted percutaneous repair (see Fig. 3.17). More complex anatomy, such as cleftlike pathology and commissural jets, is likely more challenging to address with this technique,
although data are growing that this anatomy can be adequately addressed at experienced centers.
PROCEDURAL IMAGING
The first, and one of the most critical, steps in TMVR is the TSP. The TSP site should generally
be posterior and superior and approximately 4.5 cm posterior to the plane of the mitral annulus
in the midesophageal four-chamber view to provide adequate room to maneuver the device
within the left atrium (Fig. 3.18). After the TSP, 2D and 3D TEE are used to help position the
guidewire, guide catheter, and ultimately the clip and delivery system in the left atrium. Echocardiographic guidance at this stage is useful to be sure there is adequate clearance between the
device and the left atrial free wall or other sensitive structures such as the warfarin ridge or the
LAA to avoid iatrogenic trauma to the wall.
The next step involves positioning the clip over the site of regurgitation and the orientation of
the clip arms so they are perpendicular to the coaptation line of the mitral valve. This is best
Fig. 3.18 Procedural guidance during TMVR. Panel A shows the transseptal needle (yellow arrow) at the
initial site of the TSP. Current-generation TMVR devices require the TSP puncture site be at least 4.5 cm posterior to the plane of the mitral annulus (red arrow), as seen in the four-chamber view, to provide adequate room
to maneuver the device in the LA. After the TSP, the guide catheter and clip (*) are advanced into the LA, and
the device arm orientation and trajectory are best seen with live 3D TEE from the LA perspective (B). At times,
reducing the image gain may be required to better visualize the clip arms for fine adjustments (C). After
advancing the clip into the LV, live 2D TEE imaging is helpful to guide the grasping of the mitral leaflets. AML,
anterior mitral leaflet; Ao, Ascending aorta; LA, left atrium; LV, left ventricle; PML, posterior mitral leaflet.
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accomplished using a live 3D “surgeon’s view” of the mitral valve from the perspective of the left
atrium (see Fig. 3.18). 3D imaging provides an en face view of the mitral valve from the left atrial
perspective, which simplifies the process of adjusting the medial-lateral and superior-inferior trajectory of the clip. The clip arms should generally be adjusted so they are perpendicular to the coaptation
line of the mitral valve at the site of MR. For jets arising from the A2-P2 scallops, the clip arms
should generally be at 12 o’clock and 6 o’clock, whereas lateral and medial regurgitant jets may require clockwise and counterclockwise rotation of the clip arms, respectively. After the clip position is
optimized, the clip is slowly advanced across the mitral valve into the left ventricle. It can be useful
to monitor the clip trajectory as it is advanced across the mitral valve with 3D or biplane TEE imaging, because occasionally the clip trajectory may change while it is advanced into the left ventricle.
The next step involves leaflet grasping with the clip arms (see Fig. 3.18). The clip is slowly
withdrawn and advanced repeatedly in until adequate contact is made with the anterior and
posterior leaflets to grasp them simultaneously. This step requires high spatial and temporal resolution, which is optimally provided by live 2D TEE imaging. For A2-P2 jets, the typical “grasping view” is a long-axis view at a multiplane angle of approximately 120 to 140 degrees. At this
angle both clip arms are typically visible in the 2D imaging plane when properly aligned for A2P2 lesions. Lateral jets may require a slightly higher multiplane angle, and medial jets may require
a slightly lower multiplane angle, respectively. Occasionally, during device manipulation the clip
position can change, and color Doppler imaging with or without biplane echocardiography can
be useful to ensure the clip remains at the site of regurgitation.
When there is adequate contact between the device and the anterior and posterior mitral
leaflets, the clip grippers are closed to “grasp” the mitral leaflets. The first important step after the
initial grasp is to evaluate whether there is adequate leaflet tissue within the clip to ensure device
stability (Fig. 3.19). A combination of 2D and 3D imaging is used for this purpose; 3DE can be
helpful to demonstrate a clear tissue bridge, and residual leaflet mobility is typically better seen
Fig. 3.19 Postgrasp views during TMVR edge-to-edge repair. After adequate grasping of the leaflets is
performed, 3D TEE imaging can be helpful to ensure an adequate tissue bridge between the AML and PML.
The image on the left shows the typical double-orifice mitral valve from the left atrial perspective, and the
image on the right displays the mitral valve and clip (red arrow) from the left ventricular perspective. AML,
Anterior mitral leaflet; PML, posterior mitral leaflet.
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with 2D imaging. A long retrospective acquisition during grasping can be helpful to review the
grasping maneuver and to ensure adequate leaflet tissue was obtained.
If the initial tissue grasp is felt to be adequate, attention is turned to the assessment of residual MR. MR is highly dependent on loading conditions, and care must be taken to interrogate
for residual MR at a blood pressure that is similar to the patient’s normal physiologic blood pressure. After clip deployment, the assessment of MR can be complicated due to the fragmentation
of regurgitant jets and frequent eccentric jets. A quantitative approach is preferred when time
allows. Proximal isovelocity surface area (PISA) analysis can be performed but is frequently limited due to the presence of multiple and/or eccentric jets. 3D planimetry of vena contract area
using 3D color Doppler imaging can be useful to assess the residual regurgitant orifice area.
Finally, we have found pulmonary vein Doppler to be a helpful surrogate for the hemodynamic
significance of MR reduction. A significant increase in systolic forward flow in the pulmonary
veins supports a significant hemodynamic improvement in the MR (Fig. 3.20).
Before fully releasing the clip, the mean diastolic gradient should also be assessed. Generally,
a mean diastolic gradient ,5 mmHg is preferred, although the diastolic gradient is heavily influenced by heart rate at the time of the procedure and the amount of residual MR. In cases where
there is tachycardia or significant residual MR, direct planimetry of the mitral orifice area can be
helpful to establish the degree of mitral stenosis. In general, a borderline or frankly increased
mean gradient post-clip may preclude the implantation of a second clip for residual MR, or in
some cases may preclude the placement of even a single clip due to iatrogenic mitral stenosis.
Finally, safe and effective imaging for TMVR requires constant vigilance and screening for
procedure-related complications. It is important to identify potential damage to the mitral valve or
subvalvular apparatus from the device, which could result in iatrogenic MR. Cardiac chamber perforation, pericardial effusion, and cardiac tamponade can occur and result in rapid hemodynamic
compromise. Identification of the presence or absence of baseline pericardial effusion preprocedure
can be helpful to document potential changes throughout the procedure. Immediately postprocedure a small residual atrioseptal defect at the site of TSP is near universal. However, shunting is
usually relatively minor, typically left to right, and rarely requires percutaneous closure.
Fig. 3.20 Pulmonary vein flow for post-TMVR assessment of residual regurgitation. Comparison of
pre- and post-TMVR pulmonary vein flow can be helpful to determine the hemodynamic improvement after
reduction of mitral regurgitation. Panel A demonstrates clear pulmonary vein systolic reversals preprocedure
indicating severe mitral regurgitation (A, red arrow). Post-TMVR there is normalization of pulmonary vein flow
(panel B) with systolic-predominant forward flow in the pulmonary veins indicating significant improvement in
the severity of mitral regurgitation (B, yellow arrow).
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References
1. Wiley BM, Kovacic JC, Basnet S, et al. Intraprocedural tavr annulus sizing using 3d TEE and the “turnaround rule.” JACC Cardiovasc Imaging. 2016;9:213-215.
2. Khalique OK, Kodali SK, Paradis JM, et al. Aortic annular sizing using a novel 3-dimensional echocardiographic method: Use and comparison with cardiac computed tomography. Circ Cardiovasc Imaging.
2014;7:155-163.
3. Pibarot P, Hahn RT, Weissman NJ, Monaghan MJ. Assessment of paravalvular regurgitation following
TAVR: A proposal of unifying grading scheme. JACC Cardiovasc Imaging. 2015;8:340-360.
4. Kappetein AP, Head SJ, Genereux P, et al. Updated standardized endpoint definitions for transcatheter
aortic valve implantation: The valve academic research consortium-2 consensus document. J Thorac
Cardiovasc Surg. 2013;145:6-23.
5. Makkar RR, Fontana G, Jilaihawi H, et al. Possible subclinical leaflet thrombosis in bioprosthetic aortic
valves. N Engl J Med. 2015;373:2015-2024.
6. Ruile P, Minners J, Breitbart P, et al. Medium-term follow-up of early leaflet thrombosis after transcatheter aortic valve replacement. JACC Cardiovasc Interv. 2018;11:1164-1171.
7. Reddy VY, Sievert H, Halperin J, et al. Percutaneous left atrial appendage closure vs warfarin for atrial
fibrillation: A randomized clinical trial. JAMA. 2014;312:1988-1998.
8. Holmes DR Jr., Kar S, Price MJ, et al. Prospective randomized evaluation of the watchman left atrial
appendage closure device in patients with atrial fibrillation versus long-term warfarin therapy: The prevail trial. J Am Coll Cardiol. 2014;64:1-12.
9. Alkhouli M, Rihal CS, Zack CJ, et al. Transcatheter and surgical management of mitral paravalvular leak:
Long-term outcomes. JACC Cardiovasc Interv. 2017;10:1946-1956.
10. Eleid MF, Cabalka AK, Malouf JF, Sanon S, Hagler DJ, Rihal CS. Techniques and outcomes for the
treatment of paravalvular leak. Circ Cardiovasc Interv. 2015;8:e001945.
11. Feldman T, Foster E, Glower DD, et al. Percutaneous repair or surgery for mitral regurgitation. N Engl
J Med. 2011;364:1395-1406.
12. Thaden JJ, Malouf JF, Nkomo VT, et al. Mitral valve anatomic predictors of hemodynamic success with
transcatheter mitral valve repair. J Am Heart Assoc. 2018;7:e007315.
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Abstract: The field of transcatheter structural heart interventions has grown tremendously in
recent years. Because operators are not able to directly visualize the cardiac anatomy during percutaneous procedures, live imaging is a critical component of safely and successfully performing
these procedures. Interventional echocardiography has thus evolved in tandem with the growth
of structural heart procedures. Echocardiography has become an important part of preprocedural
planning, procedural guidance, and postprocedural assessment. Commonly performed procedures
include transcatheter aortic valve replacement (TAVR), transcatheter valve-in-valve implantation
or valve-in-ring implantation, closure of paravalvular regurgitation (PVR), edge-to-edge mitral
valve repair (TMVR), and left atrial appendage occlusion (LAAO), among others. Intensive interest and ongoing trials are currently evaluating transcatheter options to treat mitral regurgitation (MR) with transcatheter mitral valve replacement (valve in native annulus) or alternative
transcatheter mitral valve repair devices, as well as new devices to treat tricuspid regurgitation.
These new devices have the potential to provide treatment options for patients deemed to have a
high or prohibitive risk for conventional open surgery.
Keywords: Interventional echocardiography, transesophageal echocardiography, 2D echocardiography, 3D echocardiography, Doppler echocardiography
CHAPTER 4
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Hemodynamics for the Structural
Interventionalist
Yogesh N.V. Reddy Rick A. Nishimura
Introduction
Invasive hemodynamic assessment is a critical part of structural intervention. Imaging and hemodynamics are complementary, and both need to be mastered for effectiveness in structural heart
disease (SHD) interventions.
Indications for diagnostic invasive assessment include:
1. The diagnosis remains ambiguous after noninvasive testing.
2. There is discrepancy in the reported severity of valvular heart disease by different nonin-
vasive measures.
3. There is suspicion for pulmonary vascular disease or precapillary pulmonary arterial
hypertension.
4. A high-output state or shunt disease is suspected or of unclear severity.
Invasive hemodynamic assessment remains the gold-standard direct measurement of absolute
pressures in various chambers of the heart, which can only be indirectly estimated by Doppler
echocardiography. In addition, cardiac catheterization allows assessment of cardiac output (CO)
using the Fick and thermodilution principles, as we will discuss later.
In practical terms, cardiac catheterization is useful when there is discordance between the
clinical evaluation and diagnostic testing. Because cardiac catheterization is only performed for
those patients in whom there is a discrepancy, it takes a very meticulous approach to assure that
reliable data are obtained that answers the clinical question. This chapter will focus primarily on
the interpretation of data obtained and common pitfalls in interpretation and measurement of
hemodynamics of SHD. We will not discuss the actual technical performance of the left and right
heart catheterization, which will be well known to structural interventionalists.
Procedural Considerations
SETTING THE ZERO VALUE AT THE PHLEBOSTATIC AXIS
The standard right or left heart catheterization involves the use of fluid-filled catheters, which
measure absolute time-varying pressure in reference to an externally determined zero reference
point. By convention, the zero value is set at atmospheric pressure at the level of the right atrium.
In a supine patient, this typically corresponds to the phlebostatic axis (the intersection between
the midaxillary line and the fourth intercostal space).
Careful attention to zeroing to room air at the phlebostatic axis is important, as errors in setting
the pressure gauge at the correct phlebostatic axis height can lead to miscalibration in absolute pressures recorded. For every 10-cm error in height of the pressure gauge, there is a 7.6-mmHg error in
absolute pressure recorded. Therefore, if the pressure gauge is incorrectly set 10 cm higher than the
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true phlebostatic axis, there will be a falsely low absolute pressure by 7.6 mmHg (although relative
changes in pressure over time, such as pulse pressure or gradients, will remain accurate).
CHOICE OF RIGHT HEART CATHETER
There are typically two choices for right heart catheter use: (1) an end-hole balloon wedge catheter
or (2) a Swan-Ganz catheter with thermodilution CO capabilities. The balloon wedge catheter has
a larger lumen due to a single end hole, with the entire internal diameter utilized for pressure transmission. Therefore, when accurate pressure waveform measurements are required (such as for gradient
measurement or constriction/restriction studies), a balloon wedge catheter should be the catheter of
choice. This then requires measurement of CO by the Fick principle (which will be described later)
using pulmonary and arterial saturations. When multiple CO measurements are required throughout a case with different loading conditions, this then necessitates continuous oxygen consumption
by a metabolic cart. When this is not available, a thermodilution-capable Swan-Ganz catheter may
be preferable, although the pressure waveforms will often be damped compared with a balloon
wedge catheter due to the narrower internal luminal diameter. It is also important to remember
situations when the thermodilution CO may be inaccurate (described later), in which case the
balloon wedge catheter with direct Fick CO should be preferred.
LEFT HEART CATHETERIZATION: TRANSEPTAL VERSUS
RETROGRADE ACCESS
Measurement of left ventricular pressures requires either (1) retrograde entry into the left ventricle
across the aortic valve or (2) transseptal entry into the left atrium (LA) via a Mullens sheath with a
balloon angioplasty catheter introduced through the sheath across the mitral valve and into the left
ventricle. The technique and complications of transseptal access will be discussed in Chapter 5, but
transseptal access, even in experienced hands, does carry a small but increased risk of complications
compared with retrograde left ventricular access. Therefore it should be reserved for situations when
the information obtained by transseptal access justifies the risk, including: (1) accurate measurement
of mitral valve gradients for indeterminate severity of mitral stenosis; (2) localization and measurement
of intraventricular and outflow tract gradient in suspected obstructive hypertrophic cardiomyopathy;
(3) when high-quality left ventriculography for mitral regurgitation severity is required (because ectopy
is decreased via transseptal left ventriculogram compared with retrograde ventriculography); (4) localization of left heart pathology when trying to differentiate pulmonary vein stenosis, stiff left atrial
syndrome, or heart failure with preserved ejection fraction where direct left atrial pressure is necessary;
or (5) left heart pressure measurement in the presence of a mechanical aortic valve, where retrograde
access is not possible. In choosing an appropriate left heart catheter for hemodynamic evaluation, endhole catheters should not be used in the left ventricle. The chosen catheter should have multiple side
holes, such as in a Berman catheter, pigtail catheter, or multipurpose catheter.
USE OF HIGH-FIDELITY MICROMANOMETER PRESSURE
MEASUREMENT
Fluid-filled, catheter-based tracings often suffer from excessive whip in the pressure tracings,
which can make complex hemodynamic assessment challenging, such as the interpretation of exercise hemodynamics or assessment of ventricular interdependence in equivocal cases of suspected
constriction. In such situations, use of a high-fidelity micromanometer catheter or fractional flow
reserve coronary wire inserted into the lumen of a balloon wedge catheter can improve the diagnostic quality of the hemodynamic tracings. Although such pressure tracings are of much higher
fidelity and do not demonstrate whip artifact, they cannot measure absolute pressure in relation to
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