IMAGING STRATEGIES

A Practical Approach to Echocardiographic

Imaging in Patients With Hypertrophic
Cardiomyopathy
Carol C. Mitchell, PhD, ACS, RDMS, RDCS, RVT, RT(R), Cody Frye, BA, RDCS,
Madeline Jankowski, BS, RDCS, ACS, John Symanski, MD, Steven J. Lester, MD,
Anna Woo, MD, SM, Yvonne Gilliland, MD, Andreea Dragulescu, MD,
Theodore Abraham, MD, Milind Desai, MD, Matthew W. Martinez, MD,
Sherif F. Nagueh, MD, and Dermot Phelan, MD, PhD, Madison, Wisconsin; Charlotte,
North Carolina; Chicago, Illinois; Scottsdale, Arizona; New Orleans, Louisiana; San Francisco, California;
Cleveland, Ohio; Morristown, New Jersey; Houston, Texas; and Toronto, Ontario, Canada

Hypertrophic cardiomyopathy (HCM) is frequently unrecognized or misdiagnosed. The recently published

consensus recommendations from the American Society of Echocardiography provided recommendations
for the utilization of multimodality imaging in the care of patients with HCM. This document provides an addi-
tional practical framework for optimal image and measurement acquisition and guidance on how to tailor the
echocardiography examination for individuals with HCM. It also provides resources for physicians and sonog-
raphers to use to develop HCM imaging protocols. (J Am Soc Echocardiogr 2023;36:913-32.)

Keywords: Hypertrophic cardiomyopathy, Imaging, Echocardiography, Left ventricular outflow tract

obstruction

OBJECTIVE HCM.2 Since publication of these guidelines, the first novel myosin
inhibitor (mavacamten or Camzyos, Bristol Myers Squibb) has
Hypertrophic cardiomyopathy (HCM) is defined by the presence of received Food and Drug Administration approval for the treatment
left ventricular (LV) hypertrophy with a wall thickness in any segment of symptomatic obstructive HCM. Serial echocardiographic exams
$15 mm in the absence of other potentially causative cardiac, sys- are mandated by the Food and Drug Administration before the initi-
temic, syndromic, or metabolic diseases associated with myocardial ation of myosin inhibitors, during dose titration, and periodically
wall thickening.1,2 It is a heterogeneous disease with variability in thereafter to confirm gradient reduction and monitor for excessive
phenotype, clinical expression, hemodynamic profile, and prognosis. decline in systolic function. Consequently, it is imperative that echo-
Despite a prevalence estimated from 1:500 to as high as 1:200, HCM cardiographic laboratories are adept at recognizing HCM, deter-
is frequently unrecognized or misdiagnosed, with only 15% of mining the severity and mechanism(s) responsible for LV outflow
affected individuals being clinically identified.1-4 tract obstruction (LVOTO), and identifying features portending a
The recently published consensus recommendations from the heightened risk for sudden cardiac death.
American Society of Echocardiography (ASE) provided a framework The objectives of this document are to provide practical resources for
for the utilization of multimodality imaging in the care of patients with developing HCM imaging protocols, technical guidance for image and

From the School of Medicine and Public Health Department of Medicine, Cytokinetics, and Medtronic. M.W.M. receives financial support from Bristol
University of Wisconsin–Madison, Madison, Wisconsin (C.C.M.); Sanger Heart Myers Squibb, Cytokinetics, and Major League Soccer. D.P. is a consultant for
and Vascular Institute, Atrium Health, Charlotte, North Carolina (C.F., J.S., D.P.); Caption Health and a speaker for Pfizer and Bristol Myers Squibb. The remaining
Division of Cardiology, Northwestern Memorial Hospital, Chicago, Illinois (M.J.); authors have no conflicts to report.
Mayo Clinic, Scottsdale, Arizona (S.J.L.); Toronto General Hospital, Toronto, Rory B. Weiner, MD, FASE, served as guest editor for this report.
Ontario, Canada (A.W.); Ochsner Medical Center, New Orleans, Louisiana (Y.G.);
Reprint requests: Dermot Phelan, MD, PhD, FASE, Atrium Health Sanger Heart
Hospital for Sick Children, Toronto, Ontario, Canada (A.D.); University of
and Vascular Institute, Charlotte, North Carolina 20203 (E-mail: dermot.phelan@
California, San Francisco, California (T.A.); Cleveland Clinic, Cleveland, Ohio
atriumhealth.org).
(M.D.); Atlantic Health, Morristown Medical Center, Morristown, New Jersey
(M.W.M.); and Houston Methodist Hospital, Houston, Texas (S.F.N.).
Attention ASE Members:
Conflicts of Interest: C.C.M. has authored textbook chapters for Elsevier and is the
Login at www.ASELearningHub.org to earn continuing medical education
recipient of a W. L. Gore & Associates contracted research grant to the University
credit through an online activity related to this article. Certificates are available
of Wisconsin–Madison. M.J. is a consultant for Caption Health, is a consultant for
for immediate access upon successful completion of the activity and post-
and has received an honorarium from Bristol Myers Squibb, and is on the advisory
work. This activity is free for ASE Members, and $40 for nonmembers.
board of Echo IQ. J.S. has received research support from Bristol Myers Squibb,
Cytokinetics, Imbria Pharmaceuticals, and CorVista Health. T.A. has no financial
0894-7317/$36.00
conflicts but is a site investigator, steering committee member, or publications
committee member for trials sponsored by Bristol Myers Squibb, Cytokinetics, Copyright 2023 by the American Society of Echocardiography.
and Tenaya Pharmaceuticals. M.D. is a consultant for Bristol Myers Squibb, https://doi.org/10.1016/j.echo.2023.04.020
913
914 Mitchell et al Journal of the American Society of Echocardiography
September 2023

Abbreviations
measurement acquisition, and so- with gene variant positivity or if present in a family member of a patient
nographer reporting tools specific with HCM) and risk stratification. While HCM is often characterized by
2C = Two-chamber for the evaluation of echocardio- asymmetric septal hypertrophy, it is important to recognize that maximal
graphic findings in HCM. wall thickness may involve any LV segment.
2D = Two-dimensional  Left ventricular outflow obstruction: roughly one-third of individuals with
3C = Three-chamber HCM manifest significant LVOTO (>30 mm Hg) under resting conditions,
INDICATIONS FOR while another third exhibit obstruction only with provocation (e.g., Valsalva
3D = Three-dimensional ECHOCARDIOGRAPHY IN maneuver, exercise, or amyl nitrite inhalation). It is important to recognize
HCM that dynamic obstruction may occur at any level in the LV cavity (outflow
4C = Four-chamber
tract, midcavity, or apex). The level of obstruction has critical implications
5C = Five-chamber for patient management. Therefore, it is imperative to precisely define the
A comprehensive transthoracic presence, location, severity, and mechanism(s) responsible for obstruction.
ASE = American Society of echocardiogram (TTE),5 utilizing Systolic anterior motion (SAM) of the anterior mitral leaflet is regarded as
Echocardiography an HCM-specific protocol,1,2,4 is the hallmark of LVOTO. Small LV chamber dimension, hypercontractility,
CW = Continuous-wave recommended if there is suspi- and papillary muscle hypertrophy or displacement may produce obstruction
cion for HCM such as in the in the mid and apical regions. This distinction from LVOTO is crucial to
GLS = Global longitudinal following clinical scenarios: guide optimal patient care.2,6
peak systolic strain  Prognostic markers: several echo-derived parameters portend a heightened
 Survivor of a suspected HCM- risk of sudden cardiac death in HCM patients and may warrant consider-
HCM = Hypertrophic related sudden cardiac arrest. ation for implantable cardioverter-defibrillator therapy. These risk markers
cardiomyopathy  Confirmed diagnosis of HCM in a include the following:
LA = Left atrial, atrium first-degree relative. ◦ Massive LV hypertrophy (defined as any segment $3.0 cm). In addition,
 Symptoms suggestive of HCM consideration may be given for values $28 mm in individual patients
LV = Left ventricular, ventricle including dyspnea or chest pain based on the discretion of their physician.1
LVEF = Left ventricular with exertion (often worse post- ◦ Left ventricular apical aneurysm.
ejection fraction
prandially or with dehydration), pal- ◦ Left ventricular ejection fraction (LVEF) of < 50%.1
pitations, syncope/near-syncope.
LVOT = Left ventricular  Systolic murmur suggestive of The comprehensive HCM echo should also include a complete
outflow tract outflow obstruction on dynamic assessment of LV diastolic function as well as the degree and mecha-
auscultation (Valsalva or squat-to- nism of mitral regurgitation (MR).
LVOTO = Left ventricular stand maneuver).
outflow tract obstruction  Electrocardiogram abnormalities
MR = Mitral regurgitation including septal Q waves, ST
TECHNICAL CONSIDERATIONS FOR PERFORMING TTE IN
segment abnormalities (strain
MV = Mitral valve pattern), and T-wave inversion. HCM
PLAX = Parasternal long-axis Sonographers should also be The echocardiographic evaluation of a patient with known or sus-
PSAX = Parasternal short- encouraged to initiate the HCM- pected HCM should be comprehensive yet tailored to address the
axis specific protocol whenever pre- unique features of the individual patient. Table 1 provides guidance
liminary imaging raises suspicion on key features of the echocardiographic protocol tailored for this pa-
PW = Pulsed-wave of previously undiagnosed tient population, and a sonographer worksheet specific for patients
ROI = Region of interest HCM. The application of the with HCM is provided as a Supplementary Table.
HCM protocol does not, a priori,
RV = Right ventricular
confirm this diagnosis, and it is
Measuring Ventricular Wall Thickness
SAM = Systolic anterior important to recognize the range
motion of conditions that may mimic The interventricular septum and posterior walls are measured at end
HCM, so-called phenocopies. diastole in the parasternal long-axis (PLAX) view. End diastole is
SRT = Septal reduction defined as the first frame after closure of the mitral valve (MV) and
therapy An HCM-specific echocardio-
graphic protocol is also indicated corresponds to the peak of the R wave on electrocardiogram.5,7
TTE = Transthoracic during periodic follow-up or if Wall measurements should only include the compacted myocardium
echocardiography and should exclude papillary muscles and right ventricular (RV)
there is a change in clinical status
UEA = Ultrasound-enhancing of patients with known HCM. structures. It can be difficult to differentiate the true compacted inter-
agent Serial echocardiograms are also ventricular septum from RV structures (trabeculations, crista supra-
required for dosing in patients ventricularis, tricuspid valve apparatus, and chordae).5,7 The
taking mavacamten, which will be discussed in a later section. sonographer should utilize the ultrasound system cine function and
scroll through the cardiac cycle to optimize visualization of the true
septal thickness. The parasternal short-axis (PSAX) view can also facil-
GOALS OF THE ECHOCARDIOGRAPHIC EXAMINATION FOR itate differentiation of the compacted septum from other RV struc-
HCM tures. Measurements obtained from both planes at a comparable
level should match. Biplane imaging can also ensure measurement ac-
During the process of image acquisition, there are crucial data ele- curacy, which avoids tangential sectioning of the septum.5,7 Finally,
ments that must be integrated into the echo report given their impor- the use of ultrasound-enhancing agents (UEAs) is particularly useful
tance in patient management:1,2,4-9 in delineating the borders of the compacted myocardium.2 For the
 LV wall thickness: accurate quantitation of the degree and location of posterior wall, the electronic calipers are placed at the border of the
maximal LV wall thickness is critical for diagnosis ($15 mm or $13 mm LV cavity and compacted myocardium at the level just below the
Journal of the American Society of Echocardiography Mitchell et al 915
Volume 36 Number 9

Evaluation of Diastolic Dysfunction and Left Atrial (LA) Size

HIGHLIGHTS in HCM
Abnormalities of diastolic function are common among individuals
 Practical resources for developing HCM imaging protocols are with HCM. The comprehensive HCM transthoracic examination
discussed. should incorporate a full assessment of diastolic function, including
 Technical guidance for image and measurement acquisition in a volume-based measure of LA size, pulsed-wave (PW) Doppler
HCM patients is given. assessment of mitral and pulmonary vein inflow, tissue Doppler imag-
 Sonographer worksheet tailored for HCM-specific echocardio- ing of the mitral and tricuspid annuli, and a continuous-wave (CW)
graphic exam is shown. Doppler measurement of the peak tricuspid regurgitation velocity.9

Left Atrial Size. Indexed volume measures should be included to

MV leaflets. Care should be taken to exclude chordal structures from quantify LA size. To ensure accurate volume calculations, optimized
the measurement.5,7 The scroll function will also facilitate optimal LA images are essential. The best LA images are often not in the
visualization of the posterior wall. same plane as those for the LV. Thus, dedicated LA views for volume
Measurement of the RV free wall should also be included in the measurements should be acquired and obtained in LV end systole.
HCM examination. The RV free wall is measured in the subcostal When optimized, the base and length of the left atrium (LA) should
4-chamber (4C) view at end diastole. The measurement is made distal be measured at the largest dimensions, excluding the confluence of
to the tricuspid valve and at a distance equal to the length of the the pulmonary veins and LA appendage.5,7 The HCM Risk-SCD
tricuspid valve leaflet when fully open.7 calculator, endorsed by the European Society of Cardiology, esti-
As HCM can phenotypically manifest with asymmetric hypertro- mates the risk of sudden cardiac death in patients with HCM and
phy of any segments of the LV, evaluation of all LV segments should incorporates the LA diameter measurement. Two-dimensional ante-
be performed to define the maximal wall thickness.1,2 Also, if asym- rior-posterior linear dimension of the LA11 is recommended and
metry is present, wall thickness measurements should not be used should be obtained at end systole using a leading edge–to–leading
to calculate LV mass. Identification of LV apical obliteration, absence edge method perpendicular to the long axis of the atrium.5
of apical tapering, or an ‘‘ace of spades’’ appearance of the LV should
prompt consideration of apical HCM. For those wall segments that
Evaluation of LV Obstruction
are traditionally difficult to image such as the apical anterolateral
and anterior walls, the use of an UEA should be considered. Obstruction may occur at the level of the outflow tract (LVOTO),
midchamber, or apex. Localizing the level and mechanism of obstruc-
tion has important management implications for HCM, especially
Evaluating Systolic Function in HCM when patients are being considered for septal reduction therapies
(SRTs). Left ventricular outflow track obstruction is generally charac-
Measurement of LVEF. Quantitative assessment of LVEF, using a
terized by SAM of the anterior mitral leaflet. Systolic anterior motion
two-dimensional (2D) or three-dimensional (3D) technique, is rec-
is evaluated using B-mode imaging in the PLAX, PSAX, apical 5-
ommended whenever feasible. 3D methodology is preferred in labo-
chamber (5C), and apical 3C views. Using the scroll function back
ratories having such capability. When 3D imaging is unavailable, the
and forth, note the position of the leaflets in systole. If SAM is present,
biplane method of disks is the suggested 2D technique to evaluate
the MV will project into the LVOT during systole. Although some-
LVEF.2,5,7 The apical 4C and 2-chamber (2C) views are used to mea-
what arbitrary, SAM is considered mild when the mitral leaflets
sure the LV volume and LVEF. The measurement is made by identi-
move anteriorly during systole but remain >1 cm from the septum,
fying the end-diastolic frame in the apical 4C view and tracing the
moderate when #1 cm from the septum, and severe when there is
border of the LV chamber and compacted myocardium. The mea-
mitral leaflet–septal contact. M-mode imaging in the parasternal
surement is completed by drawing a horizontal line across the MV
views will further elucidate mitral leaflet motion and define the dura-
annulus and drawing a vertical line to the tip of the LV apex. To opti-
tion of mitral-septal contact.
mally demarcate the boundaries of the compacted myocardium,
Color Doppler and PW Doppler mapping should be integrated in
scroll back and forth using the cine function. This will help to delineate
the assessment of obstruction and, when present, determine the level
the compacted from noncompacted myocardium. After measuring
of obstruction. Mapping is performed while imaging in the apical 5C
the LVend-diastolic volume in the apical 4C view, scroll to end systole
and apical 3C views. To determine the presence and level of obstruc-
and repeat the tracing process, again using the scroll function. After
tion, utilize color Doppler, setting the region of interest (ROI) to cover
measuring the end-systolic volume in the apical 4C view, repeat the
the entire LV chamber from apex to outflow tract. A turbulent color
process in the apical 2C view. If the LV appears foreshortened,
Doppler pattern will be observed at the site of obstruction. Two-
move the transducer slightly lateral on the chest and down one rib
dimensional imaging and color Doppler are often sufficient to define
space. This maneuver will often elongate the ventricle and reduce
the level of obstruction, but if uncertainty persists, PW Doppler can
foreshortening.5
delineate the level of obstruction. This is done by placing the
Strain Imaging. Strain imaging, in particular global longitudinal Doppler sample volume at the apex of the LV and slowly advancing
peak systolic strain (GLS), complements the volumetric evaluation the sample volume into the LVOT obtaining a series of Doppler sam-
of LV systolic function. In addition to evaluating GLS, certain regional ples. This Doppler technique will show a sudden velocity increase at
variations in strain values may help differentiate HCM from other pa- the site of obstruction. After completion of mapping with color and
thologies (i.e., phenocopy conditions).10 Strain measurements are PW Doppler, proceed with CW Doppler to demonstrate the
made from tracking cardiac wall motion in the apical 3-chamber maximum velocity and corresponding peak gradient associated
(3C), 2C, and 4C views. Decreased strain is frequently noted in with obstruction.2 The classic LVOTO CW Doppler profile is dagger
regions of prominent hypertrophy and fibrosis in HCM.2 shaped, with the peak velocity occurring in mid to late systole. In
 916 Mitchell et al
Table 1 HCM TTE protocol (views to take when tailoring the echocardiography examination for HCM)
Window Mode View Measurement/evaluation/tips

Parasternal B mode 1.1. Long-axis LV (Video 1) Measure LV wall thickness and chamber size.
2D measurements:
 Interventricular septum–end diastole
 Left ventricle chamber–end diastole
 Left ventricle posterior wall–end diastole
Tips:
 Be sure to measure only compacted myocardium and exclude RV structures.
 Cross-reference with PSAX views to help differentiate
RV structures from compacted septum
and avoid tangential cuts through the septum.
 Consider use of UEA if compacted septum is unclear.

Parasternal B mode 1.2. Long-axis LV (Video 2) Evaluate for SAM

M mode  Evaluate MV leaflet tips throughout the cardiac cycle
 M mode will assist with evaluating timing of SAM (blue arrow).
Tips:
 Scroll slowly through the image to define degree of SAM.
 SAM with septal contact is considered severe.

1.3.

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Parasternal M mode 1.4. Long-axis LV at the aortic valve and MV leaflet tip Evaluate for midsystolic notch and premature closure of the aortic valve and SAM (blue arrow).

Parasternal Color Doppler 1.5. Long-axis LV focus on MV Evaluate for MR.

Tips:
 MR is typically posteriorly directed when related to SAM
 If MR is anteriorly directed evaluate closely for intrinsic valve disease

Parasternal 2D 1.6. Long-axis LV focus on LA Measure LA diameter

2D measurement:
 LA diameter measured leading edge–to–leading edge in
end systole perpendicular to the long axis of the LA.
Tip:
 Measurement used in the sudden cardiac death;
HCM risk calculator endorsed by the European Society of Cardiology

(Continued )

Mitchell et al 917
 918 Mitchell et al
Table 1 (Continued )
Window Mode View Measurement/evaluation/tips

Parasternal B mode 1.7 a. Short-axis LV level of MV leaflet tips (Video 3) Evaluate for SAM.
and color
Doppler

1.7 b

Parasternal B mode 1.8. Short-axis LV level of leaflet tips Measure septal wall thickness.
2D measurement:
 Interventricular septum–end diastole.
Tips:
 Cross-reference measurements with PLAX views.

Journal of the American Society of Echocardiography

 Excellent view to differentiate RV structures from compacted myocardium.

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Apical B mode 1.9. 4C, 2C (Video 4, 4C; Video 5, 2C) Quantify biplane LVEF.
2D measurements:
Biplane method of disks for estimating ejection fraction
 LV end-diastolic volume
 LV end-systolic volume

Apical B mode 1.10. 4C, 2C Quantify LA volume :

2D measurements :
Biplane method of disks for estimating LA volume index
 LA volume end systole
Tip:
 Nonforeshortened view of the LA often differs
from the nonforeshortened view of the LV.
Tilt the probe to obtain the largest LA volume view.

Apical B mode 1.11. 5C and 3C (Video 6, 5C; Video 7, 3C) Focus on MV to evaluate for SAM.
Tips:
 Note abnormalities of the MV subvalvular apparatus
such as abnormal chordal attachments, direct
papillary muscle attachment to the leaflet,
hypermobile or hypertrophied or displaced papillary muscles.
 Note length of the MV leaflets in diastole if there is LVOTO.
 Note severity of SAM.

Apical B mode 1.12. Measurement of MV leaflets 3C Measurement of MV leaflets

2D measurements:
 End diastole: measure total length
of the anterior and posterior leaflets
of the MV (gold lines) from annulus to leaflet tip.
 First frame of systole: measure the anterior and
posterior residual leaflet coaptation length (red lines).
These measurements may be important for surgical planning.
Tips:
 Apical 3C view is often the optimal
view to measure MV leaflets; PLAX view is an alternative option.

Mitchell et al 919
(Continued )
 920 Mitchell et al
Table 1 (Continued )
Window Mode View Measurement/evaluation/tips

Apical Color Doppler 1.13. 5C and 3C (Video 8, 5C, Define level of obstruction with color Doppler.
B mode; Video 9, 5C, color Doppler, Tip:
Video 10; apical 3C, B-mode, and color Doppler)  Set ROI to cover the entire LV from apex to the aortic valve to define location of obstruction.
 Compare the B-mode and color Doppler image simultaneously to define the location of
obstruction

1.14.

Apical PW Doppler 1.15. 5C and 3C Define level of obstruction with PW Doppler

Tip:
 Sequential PW Doppler mapping of the
LV from apex to the aortic valve to define
location of obstruction; this may not be
necessary if location of obstruction is

Journal of the American Society of Echocardiography

clearly defined on B-mode/color Doppler.
Example provided shows aliasing at the LVOT.
 On some systems, once a certain
velocity is reached the system will
use high pulse repetition frequency (HPRF)
to demonstrate the level of obstruction
without aliasing; however, multiple gates are
used with the HPRF setting, which may
make it difficult to assess the exact location
of the obstruction. Operators should be aware
of whether their system will automatically go into HPRF.

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Journal of the American Society of Echocardiography
Apical CW Doppler 1.16. 5C and 3C Quantify the severity of obstruction at rest.
CW Doppler measurement:
 Measure peak dynamic gradient. Label appropriately. For example, if the gradient is across the
LVOT, label as ‘‘resting LVOT gradient.’’
 Measure peak velocity to determine presence of obstruction and grade severity.
Tip:
 MR signal can contaminate the LVOT flow acceleration. If there is concern for this, move the
transducer more laterally and angulate the probe to align the CW Doppler beam through the
LVOT and aorta, avoiding the LA.
 Obtain and label LVOT jet then sweep the probe into the MR jet to highlight differences in
velocities and Doppler profiles between the 2 jets.

1.17.

Apical Provocative maneuvers; 1.18. 5C and 3C (Video 11) Assess level of dynamic obstruction while patient performs a provocative maneuver (Valsalva).
B-mode and Color Doppler Tip:
 Practice the maneuver with the patient beforehand and define the best probe position to obtain
optimal imaging during provocation.
 Record a cine clip while the maneuver is being performed with B-mode and color Doppler to
define whether SAM occurs/worsens or whether there is another location of worsening
obstruction (such as the midcavity).

(Continued )

Mitchell et al 921
 922 Mitchell et al
Table 1 (Continued )
Window Mode View Measurement/evaluation/tips

Apical Provocative maneuvers 1.19. 5C and 3C Quantify the severity of obstruction with provocation.
with CW Doppler CW Doppler measurement:
 Measure peak dynamic gradient and label appropriately. For example, if the gradient is across
the LVOT (label as ‘‘LVOT gradient with provocation’’).
 In the example provided, panel A represents a resting CW Doppler waveform, while panel B
represents a CW Doppler waveform with Valsalva

Apical Color Doppler 1.20. 3C, 4C, and 5C (Video 12) Evaluate for MR.
Tips:
 MR is typically posteriorly directed when related to SAM.
 If MR is anteriorly directed evaluate closely for intrinsic valve disease.

Apical Strain 1.21. Strain Measurement:

 GLS
Tips:
 Ensure apical views are not foreshortened and that the apex is placed as vertical as possible
 Confirm that tracking is moving with the walls to show areas of decreased strain
 Record parametric ‘‘bull’s-eye’’ segmental strain map to assess for regional patterns in strain.
 Regional longitudinal strain is reduced at sites of hypertrophy and fibrosis, which provides a
characteristic bull’s-eye pattern in HCM. Example provided shows global reduction in strain
most prominent in the septal regions consistent with a patient with septal predominant HCM.

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Apical 4C Spectral Doppler 1.22. Diastolic function assessment Measurements:
Tissue Doppler Mitral inflow velocities (panel A)
 E-wave velocity
 A-wave velocity
Tissue Doppler velocities (panels B, C, E)
 Annular tissue Doppler velocities (e’, a’, and s’) for MV (septal, lateral), tricuspid valve (lateral),
and pulmonary vein inflow (panel D).
 Measure S wave; D wave; A reversal; A duration
TR velocity (panel F)
 Maximum velocity for RV systolic pressure estimation
Tips:
 Adjust Doppler velocity scale setting to demonstrate Doppler waveform at maximum size for
measurement.
 Optimize sample volume sizes for each location (1-3 mm at MV leaflet tips; 5-10 mm for tissue
Doppler imaging)
Tissue Doppler
 Use tissue Doppler imaging preset.
 Optimized for low-velocity assessment.
Tricuspid regurgitation velocity
 Demonstrate best tricuspid regurgitation velocity signal.
 Adjust alignment to be parallel to flow.
 Multiple measurements and adjustments to identify maximum regurgitant velocity.
Pulmonary vein inflow
 Increase color Doppler gain to best show the pulmonary veins.
 Align parallel to flow.
Subcostal B mode 1.23. 4C 2D measurement
 Right ventricle free-wall end diastole

(Continued )

Mitchell et al 923
 924 Mitchell et al
Table 1 (Continued )
Window Mode View Measurement/evaluation/tips

Apical 3D 1.24. 3D Measurements:

 3D LVEF
 3D LV mass index
Tips:
 Optimize line density by narrowing sector width to only include the LV.
 Use multibeat acquisition if in sinus rhythm.
 Aim for at least 20 volumes/sec for heart rate <80 beats per minute.
 Use breath hold techniques

UEA 1.25. 4C, 2C, 3C (Videos 13, 4C; 14 2C; 15, 3C) UEAs
Tip:
 Use in all cases of apical hypertrophy or those with mid/distal cavity obstruction to evaluate for
apical aneurysm.
 Can improve accuracy of measured wall thickness in some cases.

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contrast to an MR signal, the LVOTO profile will stop at the aortic demonstrate the location and direction of the MR jet. This may
closure click and there will be a flow void during the isovolumic relax- require multiple passes through the MV and off-axis views to best
ation period. After obtaining the mapping and initial CW Doppler, display the MR jet. Position the CW Doppler cursor in the path of
provocative maneuvers (Valsalva, squat to stand, or amyl nitrite inha- the color Doppler MR jet and acquire and label the signal. After ob-
lation) should be performed with reassessment of peak velocity and taining this signal, realign the Doppler path through the LVOT and la-
gradient. Optimal techniques for performing provocation are pro- bel accordingly.
vided in detail in the 2022 ASE recommendations, and further tips
are provided in Table 1. In short, Valsalva (forced exhalation against Assessing Midcavity Obstruction
a closed glottis) should be maintained for >10 seconds at a high pres-
Midcavity obstruction is the product of a small LV chamber and hy-
sure (>40 mm Hg if pressure can be monitored). When performing a
perdynamic contractility resulting in systolic obliteration of the LV
squat to stand maneuver, the patient should be asked to squat for
cavity. Hypertrophied papillary muscles often contribute. We empha-
3 seconds than asked to stand. This is repeated approximately 5 times
size the importance of differentiating this phenotypic expression from
before imaging. Amyl nitrate is a vasodilator that is inhaled prior to im-
LVOTO as, in the absence of LVOTO, isolated midcavity obstruction
aging. For each of these provocative techniques, it is important to
is considered to be ‘‘nonobstructive’’ HCM. Color Doppler imaging
explain to the patient the purpose of performing the technique and
can identify turbulent midcavity flow, while PW Doppler will demon-
the method of how to do the maneuver, demonstrating for them
strate a corresponding increase in velocity at this level. The typical CW
where possible. Similar to when evaluating obstruction during resting
Doppler waveform associated with midventricular obstruction from a
imaging, 2D/B-mode and color Doppler images in addition to CW
hyperdynamic LV displays the velocity peaking in late systole.12 In
Doppler should be obtained with provocation to demonstrate the
some individuals with midcavity obstruction associated with an apical
site and severity of obstruction. Exercise stress echocardiography
aneurysm, the Doppler profile peaks in midsystole followed by a
may also be indicated to evaluate for labile obstruction.2 The
signal void and subsequent rapid diastolic flow away from the trans-
Valsalva maneuver is less sensitive than exercise for provoking
ducer as blood escapes from the aneurysm (Figure 2).13
LVOTO, and the magnitude of the provocable LVOT gradient is lower
following the Valsalva maneuver than with exercise. It should be
recognized that gradients are dynamic and highly influenced by Assessing Apical HCM
loading conditions, adrenergic tone, prandial state, and timing of The apical variant of HCM demonstrates prominent hypertrophy
medication administration. confined to the apical segments with an ace of spades–shaped LV
chamber. This variant is easy to overlook unless meticulous echo im-
Assessing Structural Abnormalities Associated With aging is performed. Apical views should be optimized and foreshort-
LVOTO ening avoided to ensure appropriate apical imaging. A UEA is
indicated in such cases to fully delineate the magnitude of regional hy-
The anatomic features and mechanism contributing to SAM and
pertrophy and determine the presence of an apical aneurysm.
LVOTO are detailed in the 2022 ASE recommendations2 and not re-
viewed in detail here. In brief, features such as elongation of 1 or both
mitral leaflets; hypertrophied, hypermobile, and apical/anteriorly dis- Assessment for Apical Aneurysm
placed papillary muscles; abnormal chordal attachments including When hypertrophy is most prominent in the midcavity or apical seg-
direct papillary muscle insertion to the MV leaflets; and acute angula- ments, the apex must be carefully inspected for the presence of an
tion of aortic takeoff with concomitant basal septal prominence are apical aneurysm and associated thrombus.
features that may contribute to LVOTO and should be noted. Left In patients with HCM, it is important to distinguish between an api-
ventricular hypertrophy and turbulent LVOT flow may occasionally cal pouch and an apical aneurysm. An apical pouch is defined as a
result from a subaortic muscular ridge or membrane and should persistent apical cavity in systole (with the apical cavity dimension
not be confused with HCM. Transesophageal echocardiographic im- in end systole greater than the midventricular cavity dimension at
aging may be required for clarification. While most recognize LVOTO end systole). An apical aneurysm is defined as a discrete, thin-
as a key element of HCM, it must be noted that LVOTO occurs in walled dyskinetic or akinetic segment of the most distal portion of
several non-HCM conditions (see further details in the 2022 ASE rec- the apical cavity.14
ommendations).2 Supplemental imaging and suggested protocols specific for the
evaluation of HCM are presented in Table 1.
Mitral Valve Regurgitation in HCM
Systolic anterior motion often distorts normal mitral leaflet coapta-
tion, resulting in a mid to late-systolic jet of MR, which is typically PRACTICAL CONSIDERATIONS FOR STRESS
directed posteriorly and laterally. Less frequently, the jet may be cen- ECHOCARDIOGRAPHY IN HCM
tral or anteriorly directed. These alternate MR jet trajectories may
contribute to contamination of the LVOT CW Doppler signal and if There are important differences in patient preparation for exercise
not appreciated may result in an erroneously overestimated LVOT testing in HCM in contrast to studies performed for ischemia evalua-
gradient. To avoid signal contamination, care should be taken to align tion. Exercise echocardiography has recognized limitations when em-
the CW Doppler beam away from the LA. This is best achieved by ployed for evaluation of epicardial obstructive coronary disease in
moving the probe more laterally from the standard apical window patients with HCM.2 The primary clinical utility of stress echocardiog-
and utilizing steeper, off-axis sampling (Figure 1). Directing the raphy in HCM is to identify occult LVOTO and dynamic MR, which
Doppler beam through the MV first will display the velocity and may be responsible for effort-related symptoms in such individuals.
timing of the MR Doppler waveform. Use color Doppler to Therefore, the stress echo imaging protocol must address SAM,
926 Mitchell et al Journal of the American Society of Echocardiography
September 2023

Figure 1 (A) Standard 5C view with the CW Doppler cursor directed through the LVOT and into the LA (arrow) with the potential to
capture a mitral regurgitant jet. (B). Off-axis 5C view with CW Doppler cursor directed through the LVOT into the aorta, avoiding the
potential to contaminate the outflow tract signal with MR.

LVOT gradient, MR, and RV systolic pressure both at rest and after ex- meal before testing to produce conditions most likely to potentiate
ercise. A UEA should not be utilized in the HCM stress echocardiog- LVOTO.
raphy protocol as MV imaging is compromised and regional wall Exercise can be performed utilizing various platforms including
motion assessment is not a priority in this setting. treadmill, upright, semirecumbent, or recumbent cycle ergometry.
The physiological response to exercise while on medical therapy is Upright exercise typically provokes higher gradients compared with
important for clinical management. Therefore, medical therapies supine exercise as the latter results in higher preload and afterload
(such as beta-blockers) should not be withheld prior to testing. In addi- conditions and a lower heart rate response. While upright exercise
tion, some experienced HCM centers also recommend ingesting a is preferentially performed, image acquisition during exercise is

Figure 2 Echocardiographic findings in a patient with midcavity obstruction with an apical aneurysm. (A) Apical 4C view demon-
strating midcavity obstruction. (B) Color Doppler localizes level of obstruction. (C) Pulsed-wave Doppler at the level of obstruction
shows narrow flow acceleration in early systole (yellow arrow) with a signal void in midsystole (blue arrow) and an aortic closure click
at end systole (red arrow), followed by further flow in early diastole as blood is released from the high-pressure apical aneurysm into
the LV chamber (white arrow).
 Volume 36 Number 9
Journal of the American Society of Echocardiography
Table 2 HCM exercise stress echocardiography protocol

Resting images

Window Mode View Measurement/evaluation/tips

Apical B mode resting 2.1 5C (Video 16) and 3C (Video 17)  Evaluate for level of obstruction (SAM with LVOTO vs
imaging midcavity vs none).
sequence  UEA should not be used as the MV is the structure of
interest and it will not be seen with UEA.
 Determine which view (5C or 3C) optimally evaluates the
MV and LVOT gradient and record cine clip.

Apical Color Doppler 2.2 5C (Video 18) and 3C (Video 19)  Set color Doppler ROI over the LV and LA to assess the
resting imaging level of obstruction and degree of MR. This can be
sequence performed with B-mode imaging using Color Compare.

Apical CW Doppler resting 5C and 3C  Perform CW Doppler across the LVOT and measure the
imaging 2.3 peak gradient.
sequence  Document the heart rate.
 If there is concern for contaminating MR, sweep the
Doppler beam from the LVOT into the MR and label.

Mitchell et al 927
Apical CW Doppler 4C tricuspid valve  Evaluate and measure peak velocity tricuspid valve.

(Continued )
 928 Mitchell et al
PLAX, PSAX, Apical B mode 2.4 Apical 4C, 2C, 3C  Perform routine LV exercise stress echocardiography
PLAX LV views.
PSAX LV (Video 20)

Postexercise
Apical B mode post- 2.5 5C or 3C (depending on  Quickly evaluate for SAM.
exercise imaging best view for evaluation of SAM and LVOT  UEA should not be used as the MV is the structure of
sequence gradient identified interest and it will not be seen with UEA.
during rest imaging; Video 21)

Journal of the American Society of Echocardiography

2.6 (Video 22)

September 2023
 Volume 36 Number 9
Journal of the American Society of Echocardiography
Apical Color Doppler Same as prior view  Set color Doppler ROI over the LV and LA to assess the
post-exercise level of obstruction and degree of MR. This can be
imaging sequence performed with B-mode imaging using Color Compare.

Apical CW Doppler post- Same as prior view  Perform CW Doppler across the LVOT and measure the
exercise imaging 2.7 peak gradient.
sequence  Perform as quickly as possible from the time imaging
begins using B-mode and color Doppler data to align the
Doppler beam.
 If there is concern for contaminating MR, sweep the
Doppler beam from the LVOT into the MR and label.

2.8

Apical B mode post- 5C or 3C (REPEAT using the  Quickly evaluate for SAM
exercise imaging second apical view)  UEA should not be used as the MV is the structure of
sequence interest and it will not be seen with UEA.

Apical Color Doppler Same as prior view (REPEAT  Set color Doppler ROI over the LV and LA to assess the
post-exercise second apical view) level of obstruction and degree of MR. This can be
imaging sequence performed with B-mode imaging using Color Compare.

Apical CW Doppler post- Same as prior view (REPEAT  Perform CW Doppler across the LVOT and measure the
exercise imaging second apical view) peak gradient.
sequence
Apical CW Doppler post- 4C tricuspid valve  Evaluate and measure peak velocity tricuspid valve.
exercise imaging
sequence

Mitchell et al 929
PLAX, PSAX, B mode Apical 4C,2 C, 3C  Perform routine LV exercise stress echocardiography
Apical PLAX LV views.
PSAX LV
930 Mitchell et al Journal of the American Society of Echocardiography
September 2023

Figure 3 (A) Color Doppler image of the anteroseptum in a PLAX view demonstrating septal perforator to LV fistula postmyectomy.
Note that flow is only seen in the LVOT without any flow noted in the RV. (B) Continuous-wave Doppler profile revealing primarily dia-
stolic flow into the LV. Also, note the high-velocity diastolic flow (approximately 3.5 m/sec). (C) Color M mode confirming timing of
flow in diastole (white arrows).

more technically challenging. Therefore, it is necessary to reposition CONSIDERATIONS FOR SERIAL ECHOCARDIOGRAPHY
the patient to a supine, left lateral decubitus position immediately af- FOR PATIENTS ON MYOSIN INHIBITOR THERAPY
ter exercise to assess LVOT gradients.2 Semirecumbent or fully
recumbent cycle ergometers have the advantage of allowing for imag- As noted previously, therapy with the novel cardiac myosin inhibitor,
ing during exercise. mavacamten, mandates regular echocardiographic imaging to guide
The suggested stress imaging sequence begins with the apical win- dosing based on the LVOT gradient and to monitor for excessive
dow with optimized apical, 5C, and 3C images (Table 2). Select the reduction in LVEF. During the initiation phase of mavacamten ther-
view that provides the best visualization of the MV. Obtain B-mode apy an echocardiogram is required every 4 weeks until week 12.
images of the LVOT to assess MV motion and presence of SAM. The maintenance phase then requires an echocardiogram every
Employ color Doppler to define turbulence in the LVOT, midven- 12 weeks indefinitely while on treatment. During this early experi-
tricle, and LA as indicators of obstruction level and dynamic MR. ence with the use of mavacamten, some centers wish to perform
This can be done by using a dual-screen function to simultaneously complete echocardiographic studies while others are opting for an
demonstrate a grayscale (B-mode) image and the same image with co- abbreviated study to facilitate throughput. The only 2 data points
lor Doppler. Next, obtain the CW Doppler signal through the LVOT, that are mandated are LVEF and LVOT gradient with Valsalva.
measuring peak velocity to calculate the peak LVOT gradient. Given the impact these data points have on therapy, a few recom-
Multiple samples should be acquired to identify the highest, uncon- mendations are worth making.
taminated LVOT velocity. Measurement of the mean LVOT gradient
is not necessary. Repeat this 3-sequence series of assessments from 1. Create a laboratory standard for provocation and provide dedicated
the alternate apical view (3C or 5C). Finally, perform CW Doppler training to a small team of sonographers who will perform these echocar-
diograms. This will facilitate the development of experience in optimizing
interrogation of the tricuspid regurgitation signal to assessment of
imaging for evaluation of LVOT gradients with Valsalva and other provoc-
peak RV systolic pressure. After completing these views and mea- ative maneuvers.
sures, obtain the remaining conventional exercise echocardiography 2. Left ventricular ejection fraction should be quantified using volumetric
imaging of the left ventricle (LV; apical 4C, 2C, 3C, PLAX, PSAX) us- analysis. While the 2D biplane method was used in the clinical trials, there
ing an identical imaging sequence postexercise as obtained at rest.1,2,4 are advantages to 3D LVEF quantification where issues of apical
Journal of the American Society of Echocardiography Mitchell et al 931
Volume 36 Number 9

foreshortening and geometric assumptions are less of a problem. Which-  Left ventricular ejection fraction and LV size (based on indexed volume)
ever method is employed on the initial study should be utilized on serial  Pattern of hypertrophy (basal septal, reverse septal curvature, apical, etc.)
testing.15  Site and severity of maximal wall thickness
3. Encourage liberal use of UEAs for the evaluation of LVEF if endocardial  The presence, location, and severity of obstruction both at rest and with
border delineation is suboptimal. provocation
4. Other metrics of cardiac function, including diastolic function, GLS, and the  The presence of an apical aneurysm (and presence of apical thrombus)
degree of MR, may serve as supportive markers of changes in systolic  Severity and mechanism of MR
function.
5. Side-by-side comparison with the prior echocardiogram must be performed
particularly if a change in LVEF or LVOT gradients is being reported. CONCLUSION

Hypertrophic cardiomyopathy is a common condition with a diverse

CONSIDERATIONS FOR ECHO IMAGING AFTER SRT
phenotypic expression that all too often goes unrecognized or is mis-
diagnosed. Echocardiography plays a fundamental role in the diag-
The 2020 American College of Cardiology/American Heart
nosis, risk stratification, and ultimately the management of patients
Association guidelines1,4 for the diagnosis and treatment of patients
with this disorder. Due to variable disease-specific manifestations
with HCM provide a class 1 recommendation for the performance
and dynamic pathophysiology, HCM-specific echocardiographic im-
of an echocardiogram 3 to 6 months after SRT. However, a limited
aging protocols are essential for comprehensive assessment under
predischarge examination should be performed if there is concern
resting and exercise conditions. This paper provides a practical frame-
for complications including a ventricular septal defect, new or wors-
work to guide echocardiographic laboratories in the development of
ening aortic or MR, or a pericardial effusion. It is important to recog-
HCM-specific protocols. Step-by-step instructions with practical tips
nize the difference between an unroofed septal perforator (generally
to optimize image acquisition and facilitate measurement accuracy,
benign) and a ventricular septal defect (which often requires interven-
as well as recommendations for obtaining key clinical data elements
tion; Figure 3). Note that residual LVOT gradients are not uncommon
for inclusion in the comprehensive TTE report, are highlighted.
in the early postprocedural setting due to associated injury and
Finally, strategies for addressing imaging requirements for unique clin-
edema. Assessment for residual LVOTO is best performed 3 to
ical scenarios, such as for those treated with myosin-inhibitor therapy
6 months after the procedure.
or post-SRT, are addressed.
Prior to imaging and reporting it is important to review the opera-
tive/procedural report to determine details and note any
intervention-related complications such as complete heart block
REVIEW STATEMENT
requiring pacemaker placement, ventricular septal defect, aortic
regurgitation, pericardial effusion, and so on. Procedural details
Given his role as Associate Editor, Sherif F. Nagueh, MD, FASE, had
should be noted in the echocardiographic report including the
no involvement in the peer review of this article and has no access
following:
to information regarding its peer review. Full responsibility for the
 Limited vs extended myectomy, midventricular resection, or apical aneu- editorial process for this article was delegated to Rory B. Weiner,
rysm resection MD, FASE.
 Papillary muscle reduction or realignment
 Mitral valve leaflet repair or plication
 Resection of minor chords SUPPLEMENTARY DATA
 Additional procedures: MV replacement, coronary artery bypass graft,
modified maze procedure, LA appendage ligation, permanent pacemaker, Supplementary data to this article can be found online at https://doi.
or cardioverter-defibrillator implantation org/10.1016/j.echo.2023.04.020.
Key data elements that should be included in the post-SRT echo-
cardiogram are as follows:
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