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The left
atrium
in 3D
Laura Ernande, MD, PhD
Post-doctoral research fellow
Harvard medical school
Massachusetts General Hospital
Boston, USA
Learning objectives
1. Left atrial anatomy
1. Assessment of the left atrium by 3D echo
1. Clinical applications
Left atrial anatomy
Location of the LA
• Most posteriorly situated
cardiac chamber
• More posteriorly and
superiorly situated / RA
• Neighborhood:
• tracheal bifurcation,
• esophagus,
• and descending thoracic
aorta
Ho SY, Circ Arrhythm Electrophysiol 2012;5:220-228.
Structure of the LA
• LA:
• begins at the pulmonary
veno-atrial junctions
• => atrioventricular
junction at the mitral
orifice.
• 3 parts:
• Venous component
• Vestibule
• Appendage (LAA)
Ho SY, Circ Arrhythm Electrophysiol 2012;5:220-228.
Ho SY, Eur J Echocardiograph 2011;12:i11-i15.
LA walls
• LA walls are muscular:
•
•
•
•
•
superior
posterior
left lateral
septal (or medial)
anterior
Ho SY, Circ Arrhythm Electrophysiol 2012;5:220-228.
The septal wall
• Oblique with the LA more
posterior than the RA
• Site of the true septum = thin
flap valve of the fossa ovalis +
muscular rim (limbus)
• In 18% of individuals, the rim is
flat => no clear distinction
between the two structures
• On the LA side, the thin fossa
valve usually indistinguishable
Faletra FF, J Am Soc Echocardiogr 2011;24:593-9.
Ho SY, Eur J Echocardiograph 2011;12:i11-i15.
The septal wall:
anatomic variations
• Aneurysmal fossa valve
• saccular excursion of > 1 cm away from the
plane of the AS
• 1/3 of hearts with aneurysmal fossa are
associated with a PFO
• Patent foramen ovale: 25% adults
• Lipomatous hypertrophy of the AS:
• Epicardial fat: 1–2 cm in the normal heart
• Thickness >2 cm (8%)
• Variation of location and size of the FO:
If anteriorly situated => close to the aortic root
=> risk of perforation
Kutty S, JACC 2012;59:1665-71.
Pulmonary veins
• PV enter the posterior part of the LA
• Left veins more superior than the right
veins
• Inferior venous orifices more posterior
than the superior
• RUPV passes behind the junction
between the right atrium and the SCV
• RLPV passes behind the intercaval area
• Left lateral ridge between the
appendage and the left pulmonary
veins (can be mistaken for a thrombus
or atrial mass)
Ho SY, Circ Arrhythm Electrophysiol 2012;5:220-228.
Pulmonary veins: anatomic variations
• Typical anatomy:
- 2 right (82%) and 2 left pulmonary (91%) venous orifices
• Common variations:
short or long common venous trunk on
the left side (8.5%)
supernumerary veins on the right side
(17%)
Thorning C, Clin Imaging. 2011;35:1–9.
Left atrial appendage
• Finger-like, multilobular extension
from the LA body
• LAA orifice between the LUPV and
the LV
• Smaller than the RAA
• Externally: multiple crenellations
• Endocardial aspect: heavily
trabeculated with muscular
structures (pectinate muscles)
• Close to the circumflex artery
Left atrial appendage
Sinus rythm
• LAA remodeling in patients
with AF
• Dilation
• Reduction in pectinate muscle
volume
• Endocardial fibroelastosis:
endocardial thickening with fibrous
and elastic tissue
Atrial fibrillation
• AF thombi located in the
LAA in 90% of the patients
Blackshear JL, Ann Thorac Surg 1996; 61:755-9. Shirani J, Cardiovasc Pathol 2000;9:95–101.
The vestibule
• Outlet part of the atrial
chamber surrounding the
mitral orifice
• Myocardium of its distal parts
overlaps the atrial surfaces of
the mitral leaflets
• Proximal border unclear,
especially in the anterior,
septal, and inferior portions.
Ho SY, Circ Arrhythm Electrophysiol 2012;5:220-228.
Assessment of the
LA by 3D echo
EAE/ASE recommendations
3D imaging of the atrial septum
and the fossa ovalis
• 2D TEE 90° bicaval plane view
• Zoom:
• Dimension as large as
possible in the x (lateral)
and z (elevation)
directions, to include the
entire IAS and surrounding
structures
• while the y (depth) direction
should be set to include only
the left and the right sides of
the septum
• 90° up-down angulation
of the pyramidal data set
=> En face view of the left side
of the septum
Lang RM, EAE/ASE recommendations. Eur Heart J CVI 2012;13:1-46.
Faletra FF, J Am Soc Echocardiogr 2011;24:593-9.
3D imaging of the atrial septum
and the fossa ovalis
• Orientation:
• RUPV at the one
o’clock position
• MV left lower
corner
• 180°
counterclockwise
rotation
=> right side of the
AS with the fossa
ovalis
Lang RM,
EAE/ASE recommendations
Eur Heart J CVI 2012;13:1-46.
MV
3D imaging of the atrial septum
and the fossa ovalis
Right atrial perspective
• The fossa
ovalis:
depression
• Gain not too
low
=> Risk of false
impression of an
ASD
Lang RM, EAE/ASE recommendations. Eur Heart J CVI 2012;13:1-46.
Faletra FF, J Am Soc Echocardiogr 2011;24:593-9.
3D imaging of the atrial septum
and the fossa ovalis
Left atrial perspective
• IAS appears
flat
• The fossa
ovalis is not
recognizable
Lang RM, EAE/ASE recommendations. Eur Heart J CVI 2012;13:1-46.
Faletra FF, J Am Soc Echocardiogr 2011;24:593-9.
Anatomic variability of the fossa ovalis
Right atrial perspective
• High variability:
size, location
and shape
Faletra FF, J Am Soc Echocardiogr 2011;24:593-9.
3D imaging of the pulmonary veins
• Midesophageal 90°
TEE view of the mitral
valve and LAA
• Slight counter clockwise
rotation
=> one or both of the
left PV
• LLPV more difficult to
visualize than the LUPV
Lang RM, EAE/ASE recommendations. 2012;13:1-46.
3D imaging
of the pulmonary veins
• Visualize the AS in “en
face” view
• From this view the right
RV adjacent to the
septum
Long axis
• Crop of the surrounding
structures by advancing Yplane box
Lang RM, EAE/ASE recommendations. 2012;13:1-46.
Short axis
3D imaging of the LAA: multiplane
Orthogonal
views of
the LAA
Courtesy of Dr
Hélène Thibault
3D imaging of the LAA:
longitudinal view
View of
the LAA
in long
axis
3D imaging of the LAA:
from the LA
Zoomed 3D
TEE image of
the LAA
orifice as
viewed from
the left
atrium
Courtesy of Dr
Marielle
Scherrer-Crosbie
3D view of the valves from the LA
Potential clinical
applications
Clinical applications
• LA size and function measurements
• Transcatheter interventional procedures requiring transseptal puncture:
• ablation for atrial fibrillation (AF), focal atrial tachycardia (left atrial
appendage closure,
• mitral valve reconstruction
• Diagnosis and closure of ASD
• Patent foramen ovale
• LAA measurement and closure
• LA mass
LA size measurements
• Normal LA volume 22 ± 6 mL/m2
• Dilation of the LA:
Diastolic dysfunction
atrial flutter or fibrillation
significant mitral valve disease
bradycardia and 4-chamber enlargement,
anemia and other high-output states
- elite athletes
-
• LA volume index ≥ 34 mL/m2 is an
independent predictor of:
- death,
- heart failure,
- atrial fibrillation,
- and ischemic strokes
Lang RM, Eur J Echocardiogr 2006;7:79-108. Nagueh SF, Eur J Echocardiogr
2009;10:165-93. Tsang TSM, Am J Cardiol 2002;90: 1284-89.
LA volume measurement by 3D echo
2D biplane area-length
VS.
3D measurement
3D: underestimation 8%
Miyasaka Y, J Am Soc Echocardiogr 2011;24:680-6.
VS.
CT measurement
2D: underestimation 19%
LA volume: additional value of 3D echo?
• Good correlation between 2D and
3D measurements
• Absence of demonstration of an
incremental prognostic value of
the 3D measurements
LA vol <50mL
LA vol ≥50mL
Jenkins C, J Am Soc Echocardiogr 2005;18:991-997. Anwar AM, Int J Cardiol 2008;123:155–61.
Blume G, Eur J Echocardiogr 2011;12:421-30.
LA function
• 3 phases:
• Reservoir: LA stores PV
return during LV
contraction and
isovolumetric relaxation
• Conduit: the LA transfers
blood passively into the LV
• Active contraction:
contributes between 15
and 30% of LV stroke
volume
Blume G, Eur J Echocardiogr 2011;12:421-30.
Determinants of LA function
• LA size and function are
influenced by LV compliance
• LA afterload is determined by:
• Elastic properties
• LV compliance (elevated LV filling
pressures = increased LA afterload)
• LA preload:
• Volume-dependent
• Similar to the LV Frank–
Starling curve,
• LA size increases with LA volume and
pressure => gain of contractility
• Threshold fibre length => atrial
shortening and contractility begin to
decline
Blume G, Eur J Echocardiogr 2011;12:421-30.
Rosca M, Heart 2011; 97: 1982-1989.
Assessment of LA function by
echocardiography
PW Doppler evaluation of
transmitral flow
PW Doppler evaluation of
pulmonary veinous flow
Measurements of atrial
myocardial velocities
Calculation of LA
phasic volumes
Measurements of
atrial deformation
Role of 3D echo in LA function
assessment?
3D TEE-guided trans-septal punction
• Potential additional value of 3D
TEE vs. 2D TEE:
• Facilitate understanding the
morphology of the IAS
• Valuable in patients at high risk
for TSP:
extreme rotation of the cardiac
axis, repeated TSP, small size
of fossa ovalis, or aneurismal
IAS
• Facilitate the recognition of the
most appropriate site for the
puncture
3D TEE-guided transseptal punction
• 24 patients transeptal punction
for AF ablation
• Fossa ovalis clearly seen in all
24 patients.
• All punctures required a single
attempt to access left atrium.
• Total fluoroscopic time was
120.6 + 34 s.
• No major or minor
complications were
experienced.
Cherchia GB, Europace 2008;10:1325-28.
Ablation procedures
Isolation of
pulmonary
veins in a
patient
with
paroxysmal
AF
Faletra FF,
JACC CVI
2011;4:203-206.
ASD diagnosis and 3D echo
Courtesy of
Dr Hélène
Thibault
ASD diagnosis and 3D echo
Facilitates
the
diagnosis
of
multiple
complex
defects
ASD diagnosis and 3D echo
Facilitates
measurement
of the borders
and area of the
ASD
Courtesy of
Dr Hélène Thibault
ASD diagnosis and 3D TTE
• Crossover study
• 3D TTE vs. 2D TEE
• 24 successive patients with
ASD
=> 25% with poor quality
3D data
• 12 normal subjects
=> No false positive
• Complete agreement
between the 3D and TEE
regarding suitability in 15
patients (83%)
Morgan GJ, Eur J Echocardiogr 2008;9:478-482.
ASD closure and 3D echo
Patent foramen ovale
• FO= part of the normal fetal
circulation
• Birth:
increase in pulmonary blood flow =>
increased LA pressure => compression
septum primum against the septum
secundum => FO closure
• Anatomic closure incomplete: 25%
adults
• Possible association of PFO with cryptogenic strokes:
– prevalence 50 to 60% vs. 25% in the normal population
– but no demonstration in prospective studies that PFO is an
independent factor of stroke
Kutty S , J Am Coll Cardiol 2012;59:1665-71. Overell JR, Neurology 2000;55:1172-9.
Patent foramen ovale
TTE or TEE
with agitated saline contrast
Valsava maneuver
Potential additional
value of 3D TEE
Rana BS , Eur J Echocardiogr 2010;11:i19-i25.
Patent foramen ovale and 3D echo
RT3D-TEE can be useful to guide PFO device closure procedure
LAA measurements by 3DTEE
• Assessment of LAA orifice
area: Higher correlation of
RT3DTEE (than 2DTEE) with CT
• Underestimation of LAA
orifice area by RT3DTEE and
2DTEE
• But smaller bias with
RT3DTEE (0.07 cm2) than
2DTEE (0.72 cm2)
Nucifora G , Circ Cardiovasc Imaging 2011;4:514-23.
Percutaneous LAA occlusion and 3D echo
• Patients with AF/ alternative of chronic
antithrombotic therapy
• Preliminary results: feasibility and short-term
success rate
•
PROTECT-AF: Non-inferiority
• RT-3D echo is useful:
• Before the procedure: to assess anatomical suitability,
measure the ostium and detect contraindications
(thrombus)
• During the procedure: trans-septal punction and device
positioning
• At the end of the procedure: presence of residual
communication between the LAA and the main LA
• At follow-up: obliteration of the LAA and detection of
procedure complications.
Perk G , Eur Heart J CVI 2012;13:132-8.
Holmes DR, Lancet 2009;374:534 – 542.
Percutaneous LAA occlusion and 3D echo
Courtesy of Dr Marielle Scherrer-Crosbie
LA mass
Conclusions
• Imaging of the left atrium is important in clinical practice
- Because LA size is a major prognostic factor of death, heart
failure, atrial fibrillation, and ischemic stroke
- for the diagnosis of PFO and ASD
- for guided interventional procedures requiring trans-septal
puncture.
•
3D echo allows a comprehensive evaluation of LA
anatomy and function.
•
Although the additional diagnostic and prognostic
value of three-dimensional echo remains to be
demonstrated in a large part of those
pathologies/procedures, 3D echo is promising in those
settings.