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j.jcmg.2017.07.017

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JACC: CARDIOVASCULAR IMAGING
VOL.
ª 2017 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
-, NO. -, 2017
ISSN 1936-878X/$36.00
PUBLISHED BY ELSEVIER
LETTER TO THE EDITOR
repair, a 40% reduction in SI was seen in the PL,
whereas the AL showed a 23% reduction in SI.
Comparing post-repair SI data to that of normal individuals (1) revealed that mean global SI was now
Effect of Mitral Valve Repair on Mitral Valve
comparable to that of normal individuals (Figure 1B);
Leaflets Strain
Regionally, mean SI for AL was similar to that of
A Pilot Study
normal individuals, whereas the SI for the PL was
reduced (Figure 1B). No relation was found between
Primary mitral regurgitation is amenable to surgical
repair; its durability may be influenced by the surgical
approach,
underlying
pathology,
and
possibly
annular geometry and leaflet stress. Recently, we
have reported a new method to compute mitral valve
(MV) strain in humans from 3-dimensional (3D)
transesophageal echocardiography (1). We aimed to
use the developed patient-specific strain methodology to evaluate the effect of mitral valve repair (MVR)
on global and regional MV strain. The MVR technique
used was the nonresectional approach (1,2).
We performed 3D transesophageal echocardiography of the MV in 10 patients with moderately severe
or severe primary mitral regurgitation (age 64 13
years, 9 male and 1 female patient; 8 patients with
flail P2, 1 with P3 prolapse, and another with A2 prolapse) in the operating room, with a closed chest,
prior to and following repair and hemodynamic stability. All patients had successful MVR; complete
flexible ring was used: ATS ring in all but 1 patient
(size 31.8 1.4 mm). Patient-specific MV modeling
was created at mid- and end-systole from which
mitral leaflets strain was computed (3,4).
Following MVR, the mitral annulus dimensions
were significantly reduced: annulus area decreased
from 15.2 0.8 cm 2 to 5.2 0.1 cm2 and circumference
from 15.2 0.4 cm to 8.4 0.1 cm (both p < 0.05). The
exposed anterior leaflet (AL) and posterior leaflet (PL)
(AL 6.13 2.07 cm 2 and PL 8.99 2.08 cm 2) were
significantly smaller after repair (2.79 0.41 cm2 and
3.13 0.24 cm 2, respectively; p < 0.05). Although the
systolic or diastolic blood pressure and strain (r range
0.23 to
0.45, p range 0.18 to 0.62).
It is thought that any MVR technique that is associated with reduced leaflets stress will have a better
long-term outcome. Consequently, previous MVR
simulations focused on leaflets stress calculations (5).
The current study is the largest report of MV modeling
following MVR in humans. A computerized analysis of
3D echocardiography allowed in vivo, patient-specific
quantification of MV SI. We computed planar strain
tensor at several thousand points on the MV so we did
not need to introduce any elasticity hypotheses for
mitral leaflets tissue for strain calculation. Indeed,
realistic MV elasticity models are anisotropic and
highly nonlinear so that in most publications, parametrization of elasticity models for human MV relies on
stress measurements made in vivo in animal models.
The reduction in valve strain after MVR is likely
multifactorial and may be related to a smaller annular
size, increased valve coaptation zone, a smaller
exposed valve area, and the insertion of artificial
chordae, each having been shown in various models to
reduce strain. These reductions and “normalization”
in strain may contribute to the overall good intermediate to long-term outcome seen in the nonresectional
MVR technique (2). Further studies are needed to
assess the effect of different surgical repair approaches
on the magnitude and distribution of reduction in MV
strain and assess whether residual MV strain intensity
is a significant determinant of MVR durability.
operative: 0.096 0.015; p < 0.05) (Figure 1B). Before
Sagit Ben Zekry, MD*
Jeff Freeman, MS
Aarti Jajoo, PhD
Jiwen He, PhD
Stephen H. Little, MD
Gerald M. Lawrie, MD
Robert Azencott, PhD
William A. Zoghbi, MD
MVR, the PL, compared with the AL, showed higher SI
*Department of Cardiology
PL area was larger than the AL, the PL area was
proportionally reduced more so than the AL area.
An example of mitral valve strain intensity (SI) map
before and after MVR is shown (Figure 1A). For the 10
patients, a significant reduction in global SI was noted
after valve repair (pre-operative: 0.15 0.01 vs. post-
(0.19 0.02 vs. 0.13 0.01, respectively; p < 0.05).
Houston Methodist DeBakey Heart and Vascular Center
After valve repair, mean SI was significantly reduced
6550 Fannin Street
for both AL and PL to comparable values (0.09 0.01
SM 1901
for AL, 0.10 0.01 for PL) (Figure 1B). Thus after valve
Houston, Texas 77030
2
JACC: CARDIOVASCULAR IMAGING, VOL.
Letter to the Editor
-, NO. -, 2017
- 2017:-–-
F I G U R E 1 MV Strain Intensities Map and Mean Strain Intensity Pre- and Post-MV Repair
A
Pre-Operation
Post-Operation
25 Anterior Leaflet
25
0.42
20
20
5
5
0
0.22
–5
–10
–15
0.22
–10
Posterior Leaflet
–15
–20
–25
–30
0
–5
Posterior Leaflet
–20
–10
0
10
20
Strain Value
15
10
Strain Value
15
10
0.42
Anterior Leaflet
–20
0.02
–25
–30
–20
–10
0
10
20
0.02
mm
mm
B
*P < 0.05 vs Posterior Leaflet
†P < 0.05 vs Pre-Operation
‡P < 0.05 vs Post-Operation
0.20
†‡
0.15
*
†
†
†
0.10
*†
†
0.05
0.00
Pre-Operation
Post-Operation
Global
Anterior Leaflet
Normal
Posterior Leaflet
(A) An example of mitral strain intensity maps in a patient before and after mitral valve (MV) repair, showing reduction in strain
post-operatively. (B) Mean strain values for the mitral valve, the anterior and posterior leaflets pre- and post-operation, and in normal
individuals (1). Mean and SE bars are shown.
E-mail: wzoghbi@houstonmethodist.org
https://doi.org/10.1016/j.jcmg.2017.07.017
Please note: Dr. Ben Zekry received partial funding from a grant in 2009 to 2010
by John and Maryanne McCormack Cardiology Fund. Dr. Azencott and University of Houston collaborators received National Science Foundation grant
NSF-0811133 in 2008 to 2011. All other authors have reported that they have no
relationships relevant to the contents of this paper to disclose. Farooq A.
Chaudhry, MD, served as the Guest Editor for this article.
2. Lawrie GM, Zoghbi W, Little S, et al. One hundred percent reparability
of degenerative mitral regurgitation: intermediate-term results of a dynamic engineered approach. Ann Thorac Surg 2016;2:576–83; discussion
583–4.
3. Ben Zekry S, Lawrie GM, Little SH, et al. Comparative evaluation of mitral
valve strain by deformation tracking in 3D-echocardiography. J Cardiovasc
Eng Tech 2012;3:402–12.
4. Azencott R, Glowinski R, He J, et al. Diffeomorphic matching and dynamic
deformable surfaces in 3D medical imaging. Comput Meth Appl Math 2010;10:
REFERENCES
235–74.
1. Ben Zekry S, Freeman J, Jajoo A, et al. Patient-specific quantitation of mitral
5. Labrosse M, Mesana T, Baxter I, Chan V. Finite element analysis to
valve strain by computer analysis of three-dimensional echocardiography: a
pilot study. Circ Cardiovasc Imaging 2016;9:e003254.
model complex mitral valve repair. Asian Cardiovasc Thorac Ann 2016;1:
60–2.
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