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Supplemental Methods
Preclinical Study
The experimental protocol is summarized in Supplementary Figure 1.
Experimental animals
Animal procedures were approved by the National Heart, Lung, and Blood Institute Animal Care
and Use Committee. Sixteen Yorkshire pigs (weight, 30 to 35 kg) were studied. Anesthesia was induced
with the use of atropine, butorphanol, ketamine, and xylazine and maintained with the use of inhaled
sevoflurane and supplemental IV propofol and mechanical ventilation.
In-vivo CMR Data Acquisition
Imaging was performed on a 3T Siemens MAGNETOM Skyra (Siemens Healthcare, Erlangen,
Germany) using a phased array Siemens torso coil and spine array combination. In every scanning
session first and second-order shimming and frequency adjustment were performed over a local volume
(box) encompassing the whole heart. After initial localization steps to determine the short axis of the left
ventricle (LV), whole heart breath-hold retro-gated cines, B0 field maps (1), and B1 field maps (2) were
acquired for quality assessment. The protocol parameters are detailed in Appendix I. The average RR
interval was = 737 ± 82 ms.
Between 6 and 9 in-vivo DT-CMR data sets at different time points in the cardiac cycle were
acquired in two midventricular short-axis slices. The in-vivo DT-CMR stimulated-echo (STEAM) singleshot echo planar imaging (EPI) sequence with monopolar diffusion encoding used is described elsewhere
(3). The protocol parameters are detailed in Appendix I. The raw data was reconstructed using the
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product image reconstruction algorithms available on the scanner. Imaging was performed successfully in
all cases.
In-situ post-mortem CMR Data Acquisition
On completion of in-vivo imaging, intravenous unfractionated heparin (10000 U) was
administered. In 8 animals, euthanasia was achieved with hearts in a relaxed (diastolic like) conformation
by intravenous administration of KCl (4 meq/kg). In the remaining 8 animals euthanasia was achieved with
hearts in a contracted (systolic like) state by intravenous administration of BaCl2 (40 meq/kg) (4,5). All
euthanasia procedures were performed under general anesthesia.
Real time cine imaging (Appendix I) commenced before the administration of the euthanasia
agents and continued until bulk cardiac motion ceased (Supplementary Figure 2). B0 field maps and short
and long axis cines (steady state free precession SSFP, Appendix I) were acquired. For post mortem insitu DT-CMR, the in-vivo DT-CMR imaging protocol described above was continuously repeated for a
single mid-ventricular slice using a simulated ECG signal (85 bpm) for approximately one hour in N = 12
animals (N = 6 arrested with KCl and N = 6 arrested with BaCl2). In the remaining N = 4 animals (N = 2
arrested with KCl and N = 2 arrested with BaCl2), continuous in-situ DT-CMR imaging over one hour was
not performed. The KCl arrested hearts achieved their relaxed state immediately after injection and
preserved it throughout the one hour of in-situ scanning, with a wall thickness of 8±1 mm similar to that of
in-vivo diastole (7±1 mm). On the other hand, the BaCl2 arrested hearts started with a relaxed
configuration similar to that of the KCl arrested hearts, and 20-40 minutes after injection started
contracting slowly (over a time period of ~10 minutes) until they achieved a systolic configuration, with a
final wall thickness of 13±1 mm (thicker than that of in-vivo systole at 10±1 mm), which they preserved
until the end of the 1 hour scan (Supplementary Figure 2). This experiment therefore provided us with a
slow-motion cardiac contraction model unaffected by the cyclical strain effects typical of in-vivo cardiac
contraction.
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Ex-vivo CMR Data Acquisition
On completion of in-situ post-mortem imaging, hearts were excised and rinsed in normal saline.
The coronary arteries were flushed, after which, the cardiac chambers were filled with vinyl polysiloxane
(Microsonic Inc. USA). The hearts were held in place in a cylindrical container filled with a susceptibility
matched fluid (Fomblin Y-LVAC 6-06, Solvay Solexis, West Deptford, NJ) using open-cell foam.
Imaging was performed on the same CMR scanner using an 18-channel head coil. First and
second-order shimming and frequency adjustment were performed over a local volume encompassing the
whole heart. Short axis B0 maps were acquired. For ex-vivo DT-CMR imaging, a stack of short axis slices
was acquired using the in-vivo STEAM protocol described above with a simulated RR similar to that
observed during in-vivo imaging (RR~700ms). This was followed by two whole heart anatomical protocols.
The protocol parameters are detailed in Appendix I.
On completion of ex-vivo CMR scanning of unfixed hearts, hearts were fixed by immersion in a
10% Formaldehyde in phosphate buffered saline solution. Ex-vivo CMR of intact fixed hearts was
repeated as described above ~ 10 - 60 days after fixation. The STEAM protocol was adjusted to account
for the T1 shortening resulting from fixation (the simulated RR interval was decreased from ~700ms to
~300ms).
Histology
A tissue block of approximately 1 cm × 1 cm × wall thickness was cut from the lateral LV wall at
the mid-ventricular level. Each block was further subdivided according to the scheme illustrated in
Supplementary Figure 3. Each block was processed for paraffin embedded sections 10 microns thick.
Sections for HA analysis were cut every 100 microns. The initial most epicardial layers were discarded
until a flat surface with four corners was observed. Because of this, 26%±14% of the epicardial wall was
discarded, and the steepest epicardial helix angles were lost. The long axis and short axis blocks were cut
in 10 sections separated by 100 micron gap for sheetlet angle analysis. All slices were stained using
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Masson staining. A Nanozoomer Digital Pathology System (Hamamatsu Photonics K. K., Japan) was
used to acquire brightfield microscopy images of the resulting slides. After excision of tissue blocks for
histology, hearts were rescanned with the anatomical FLASH protocol described above for accurate
coregistration of the ex-vivo DT-CMR and histological data.
Clinical Study
Study Population
This study received approval from the National Research Ethics Committee. Healthy controls and
patients were prospectively recruited and gave written informed consent. Patients were selected based on
a diagnosis of either idiopathic or genetic/familial dilated cardiomyopathy (DCM) or hypertrophic
cardiomyopathy (HCM). Healthy volunteers were age and sex-matched to the patient population. The
diagnosis of DCM was made according to the World Health Organization/International Society and
Federation of Cardiology criteria (6). The diagnosis was confirmed using CMR if the left ventricular (LV)
volumes indexed to body surface area were elevated and the ejection fraction was impaired relative to
published reference ranges normalised for both age and sex (7). Evidence of significant coronary artery
disease was an exclusion factor (>50% diameter luminal stenosis in one or more coronary arteries or
positive stress testing in the form of a nuclear medicine scan, stress perfusion CMR or stress echo,
substantial infarct pattern of scar). Additional exclusion criteria were hypertensive heart disease,
tachycardia-induced cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, infiltrative
cardiomyopathy, athletic heart, significant primary valvular disease, peripartum cardiomyopathy and
myocarditis.
The diagnosis of HCM followed the 2011 ACCF/AHA Guideline for the Diagnosis and Treatment
of HCM (8) and the 2014 ESC Guidelines on diagnosis and management of HCM criteria (9). Patients
who had undergone previous alcohol ablation or septal myectomy were excluded. Healthy volunteers
were recruited after screening and exclusion in the event of: chronic medical conditions, taking regular
medication, smoking, abnormal ECG, or indexed LV volumes outside the normal range (7).
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Image Acquisition
CMR was undertaken on a 3T scanner (Magnetom Skyra, Siemens, Erlangen, Germany), with an
18 element anterior matrix coil and 8-12 elements of a matrix spine coil. The LV long and short axes were
identified, after which retro-gated balanced steady state free precession (bSSFP) images were acquired in
the 3 long axis planes and a stack of short axis slices running from the atrioventricular ring to include the
apex. These were used for volumetric analysis and to identify the timing of end systole and diastasis in
each patient for a single mid-ventricular slice of 8mm thickness.
DT-CMR was performed with the same sequence as the preclinical above. The protocol parameters are
described in Appendix I.
The linear tags were separated by 16 mm and were perpendicular to the long-axis with an
acquired spatial resolution of 2.1 × 1.7 mm in-plane and slice thickness of 6 mm. Tracking of the linear tag
within or adjacent to the mid-ventricular slice in which systolic DT-CMR images were acquired was
performed by two operators, assessing both the two and four chamber images. Diastolic DT-CMR images
were acquired at the mutually agreed position of the translocated slice.
Strain information was obtained from 2D cine spiral DENSE (displacement encoding with
stimulated echoes) data acquired using novel zonal technique (10). Acquisitions were performed using 2direction (breath-hold) or 3-direction (navigator gated) encoding, 30ms temporal resolution, 3.3x3.3mm2
spatial resolution, 8mm slice thickness and TE/TR = 1ms/15ms. Peak circumferential and radial strain
values were calculated in the same short axis slice as the DT-CMR data using MATLAB (MathWorks,
Massachusetts, USA) software provided by the University of Virginia (11).
Late gadolinium enhancement images were acquired using a standard phase sensitive inversion
recovery spoiled gradient echo (Appendix I).
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Post-Processing
DT-CMR Post-processing
All the diffusion-weighted images were post processed with custom software built using MATLAB
(MathWorks, Massachusetts, USA). Diffusion tensors and the corresponding eigensystem (set of three
eigenvalues and respective eigenvectors) were calculated for each voxel as described in Ferreira et al.
2014 (12). This analysis was performed for each slice and for each time point in all the in-vivo, in-situ and
ex-vivo DT-CMR data. The orientation of the principal (E1) and secondary eigenvector (E2) were
calculated for each tensor and defined as the primary eigenvector angle (E1A) and secondary eigenvector
angle (E2A) respectively. E1A and E2A were calculated according to the local cardiac orthogonal
coordinate system of each voxel as defined in Ferreira et al. 2014 and Basser 1995 (12,13). To calculate
E1A, the primary eigenvector E1 is projected in the local longitudinal-circumferential plane. The angle of
this projection to the circumferential axis defines E1A. HA is positive for a right-handed helix when viewed
from the apex. The projection of E1 is then used to define the plane perpendicular to it, known as the
cross-myocyte plane. This plane contains two perpendicular directions, the radial direction and the wall
tangential direction. The secondary eigenvector E2 is projected into this plane and the angle between the
projection of E2 and the tangential direction defines E2A as shown in Supplementary Figure 4. E2A is
positive if pointing to the apex and negative if pointing towards the base.
While E1A maps show a prominent transmural pattern of positive right-handed to negative lefthanded angles, the measured E2A polarity shows a less obvious spatial organization, therefore E2A were
recorded as the absolute angle, ignoring angle polarity and quantifying only angle obliquity to the local
cardiac wall.
The transverse anisotropy was calculated for all the voxels, in order to assess how
distinguishable E2 was from E3 (Supplementary Figure 5). Only a small fraction of the voxels contained
E3/E2 ratios close to 1, therefore for most voxels E2 could be discriminated from E3.
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The frequency distributions for E1A and E2A were derived as follows. First the histogram of the
relative frequency of E1A or E2A (at systole or diastole) for all the myocardial voxels for each subject (bin
size 10 degrees) was calculated. Then, an inter-subject median and interquartile range for each histogram
bin was calculated.
To analyze E1A for each slice, transmural line profiles were drawn from the LV centroid to every
epicardial voxel. The line profiles were then averaged to obtain a single normalized E1A line profile for
each DTI dataset, showing the mean range of E1A with wall depth. Since absolute E2A is not normally
distributed over the LV, the median of the absolute E2A over the LV was calculated for each DTI dataset.
All E1A and E2A data analysis performed with MATLAB. E1A range was calculated as follows: E1AR =
E1AENDO - E1AEPI (14). Values are quoted as median [interquartile range] across subjects.
For 3D visualization of diffusion, Python and Paraview (Kitware, NM, USA) software were used to
represent the tensors and the primary and secondary eigenvectors with superquadric and cylindrical
glyphs respectively. The signal-to-noise ratio (SNR) of the diffusion weighted images was measured over
the whole LV, using the multiple acquisition method described by Reeder et al. (15) and implemented in
Nielles-Vallespin 2012 (3). The mean signal-to-noise ratio (SNR) in the unaveraged b0 images over all invivo experiments was SNR = 14±3.
Cardiac Function
Ejection fraction (EF) was measured using a semi-automated threshold-based technique
(CMRtools, Cardiovascular Imaging Solutions, London, UK). The LV epicardial and endocardial borders
were defined by manual planimetry excluding papillary muscles. Mean EF = 50±6% for all in-vivo
experiments in swine.
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Histology
All the histology images were post processed with custom software built using MATLAB (MathWorks,
Massachusetts, USA). All histology images were first saved as TIFF files with a spatial resolution of
approximately 550 pixels/mm. The following steps were then applied to each block of images:
●
All images were visually inspected and removed if deemed of poor quality or with insufficient
tissue.
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An affine motion correction algorithm was used to align all remaining images (16).
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The background and regions with large arteries were then removed based on color information.
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The images were then divided in a 100x100 pixel grid.
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Each square of the grid was subsequently thresholded and an edge-detection filter was used to
detect myocyte borders and/or sheetlet cracks containing collagen.
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A Radon transform was used to detect the strongest edge direction in each grid square.
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Histograms of the detected angles for the entire grid were finally calculated for each image:
○
If analyzing HA cuts, the variation of histogram peak angle with transmural position was
compared to the plots of E1A with transmural depth obtained from DT-CMR.
○
If analyzing long-axis cuts, the histograms for all slices were averaged and the absolute
value of the angle corresponding to the largest peak was compared to the median
absolute E2A measured with DT-CMR.
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Preclinical Statistical analysis
Changes in E2A and in E1A range (E1AR = E1AENDO - E1AEPI) between diastole and systole invivo were assessed with a Wilcoxon signed rank test. Changes in E2A and in E1A range between relaxed
and contracted states in-situ and ex-vivo were assessed with a Mann–Whitney–Wilcoxon (MWW) test
using MedCalc Statistical Software version 15.11.4 (MedCalc Software BVBA, Ostend, Belgium;
https://www.medcalc.org; 2015). A linear regression was used to fit the E2A values against wall thickness
for the in-vivo data and BaCl2 in-situ contraction data. A p-value < 0.05 was considered significant.
Clinical Statistical analysis
Statistical analysis used SPSS Statistics software (v22). Normality was tested using the
Kolmogorov-Smirnov test and histograms. One-way ANOVA and Kruskal-Wallis (with follow-on pairwise)
tests were used to assess differences between groups for parametric and non-parametric data. A chisquared test was used for categorical data. A p-value of <0.05 was considered significant.
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Appendix I. CMR Protocols
Preclinical in-vivo CMR
Breath-hold retro-gated 2D TrueFISP cines: ECG-triggered, TR = 2.7ms, TE = 1.13ms, flip angle = 40°,
FOV = 320 mm x 240 mm, matrix = 192 x 144 pixels, slice thickness = 8 mm, GRAPPA parallel imaging
rate 2, BW = 1371 Hz/Px, 11 lines per shot. Views: 2 chamber, 3 chamber, 4 chamber, whole heart short
axis stack.
Breath-hold multiecho Dixon fat-water separation technique + B0 field maps (1): ECG-triggered,
readout bandwidth (BW) = 977 Hz/pixel, TE = 1.76, 3.12, 4.48 and 5.84 ms, TR = 16.5 ms, flip angle =
12°, field of view (FOV) = 360 mm × 240 mm, image matrix = 256 × 192, views per segments = 10, slice
thickness = 8 mm, and breath-hold duration 16 heartbeats. Views: 4 chamber, whole heart short axis
stack.
Breath-hold saturated double flip angle B1 mapping method (2): ECG-triggered, 45°/90° flip angles,
80 × 50 matrix, rate 2 parallel imaging (GRAPPA), 360 mm × 200 mm field of view, 8 mm slice thickness,
2 saturation bands on the chest and back to reduce the field of view, and 30 repetitions per flip angle. All
images were registered and a B1 scale factor map was calculated as B1 = arccos(abs(I90°/(2I45°)))/45,
where I45° and I90° are the signal intensities from the 45° and 90° flip angle images respectively. Views: 2
mid-ventricular short axis slices.
Cardiac Diffusion Tensor Imaging (DT-CMR) Breath-hold Stimulated echo (STEAM) single-shot EPI
with monopolar diffusion encoding (3): ECG-triggered, b0 = 50 s/ mm2 (20 averages), b = 500 s/mm2 in
6 diffusion encoding directions (20 averages), as well as b = 150 s/mm2, b = 350 s/mm2 in 6 directions (2
averages). Zonal excitation, fat saturation, repetition time TR = 2 RR intervals = 1400 ms (assuming RR =
86 beats per minute), echo time TE = 30 ms, BW = 1838 Hz/pixel, SENSE (17) parallel imaging
acceleration factor of 2, FOV = 320 mm x 120 mm, matrix = 160 x 60 pixels, EPI echo train length = 30
readouts, Echo spacing = 0.65 ms, EPI readout duration = 19.5 ms, spatial resolution = 2x2x8 mm3
interpolated to 1x1x8 mm3.
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Preclinical in-situ CMR
Real-time Cine: TR = 4.5ms, TE = 2.23ms, flip angle = 12°, FOV = 320 mm x 240 mm, matrix = 128 x 96
pixels, slice thickness = 10 mm, BW = 1502 Hz/Px, 128 lines per shot. Sagittal view.
DT-CMR STEAM single-shot EPI with monopolar diffusion encoding: as described in the in-vivo CMR
section above, using a simulated ECG signal (85 bpm). View: 1 mid-ventricular short axis slice scanned
continuously for approximately one hour after arrest.
Preclinical ex-vivo fresh CMR
3D FLASH: TR = 2.6ms, TE = 2.64ms, flip angle = 12°, FOV = 176 x 132 mm, matrix = 384 mm x 288
pixels, slice thickness = 1 mm, BW = 220 Hz/Px, averages = 2-10, voxel size: 0.6 mm × 0.6 mm × 1.0
mm. Views: Whole heart 3D short axis volume.
T2TSE: TR = 11.5ms, TE = 12ms, flip angle = 150°, FOV = 128 mm x 128 mm, matrix = 384 x 288 pixels,
turbo factor = 11, echo train per slice = 35, slice thickness = 1 mm, BW = 224 Hz/Px, averages = 2-10,
voxel size = 0.6 mm × 0.6 mm × 1.0 mm. Views: Whole heart 3D short axis volume.
DT-CMR STEAM single-shot EPI with monopolar diffusion encoding: as described in the in-vivo CMR
section above, TR = 1400 ms. Views: whole heart short axis stack.
Preclinical ex-vivo Fixed CMR
Anatomical FLASH: as described in the ex-vivo fresh CMR section above.
DT-CMR STEAM single-shot EPI with monopolar diffusion encoding: as described in the in-vivo CMR
section above, TR = 600 ms to account for T1 shortening after fixation. Views: whole heart short axis
stack.
Clinical in-vivo CMR
Breath-hold retro-gated 2D TrueFISP cines: ECG-triggered, TR = 3.4ms, TE = 1.47ms, flip angle = 52°,
FOV = 370 mm x 300 mm, matrix = 256 x 192 pixels, slice thickness = 8 mm, GRAPPA parallel imaging
rate 2, BW = 977 Hz/Px, 20 lines per shot. Views: 2 chamber, 3 chamber, 4 chamber, whole heart short
axis stack.
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2D cine spiral DENSE: FOV = 224 mm x 224 mm, spatial resolution = 3.3 mm x 3.3 mm, slice thickness
= 8mm, TR = 15ms, TE = 1ms, total number of interleaves = 4, interleaves per RR = 2, temporal
resolution = 30ms, 3 direction simple encoding, 6 mm navigators window, 3 point phase cycling artifact
suppression, 0.06 cycles/mm encoding frequency, variable flip angle (max 20°), perpendicular zonal
excitation, time reversed pair of asymmetric pulses.
Breath-hold Phase Sensitive Inversion Recovery (PSIR) Spoiled Gradient Echo for Late
Gadolinium Enhancement (LGE): ECG-triggered, TR = 4.1ms, TE = 1.55ms, flip angle = 20°, Nonselective IR, FOV = 350 mm x 300 mm, slice thickness = 7mm, matrix = 256 x 192 pixels, BW = 465
Hz/Px. Views: 2 chamber, 3 chamber, 4 chamber, whole heart short axis stack.
DT-CMR STEAM single-shot EPI with monopolar diffusion encoding: as described in the in-vivo CMR
preclinical section above: 6 diffusion encoding directions at b = 600 s/mm2 and b = 150 s/mm2 for
reference (assuming RR = 60 beats per minute), fat saturation, TR = 2RR-intervals, TE = 23 ms, SENSE
parallel imaging acceleration 2, echo train duration 13ms, acquired spatial resolution = 2.8×2.8 mm2,
reconstructed to 1.4×1.4 mm2 and 10-15 averages were acquired for the main diffusion encoding
directions (b = 600 s/mm2, one average per breath hold) and one average of the reference data.
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Supplemental Figure 1. Flow chart describing experimental design. In vivo DT-CMR was performed
in Yorkshire pigs (N = 16) at two mid-ventricular short axis slices and at six to nine time points during the
cardiac cycle. Subsequently, a single mid-ventricular short axis slice was continuously imaged with DTCMR in the intact animal in situ during the first hour after induction of cardiac arrest in both relaxed (N = 6)
and contracted (N = 8) states by intravenous administration of potassium chloride (KCl) and barium
chloride (BaCl2), respectively. The BaCl2 arrested hearts initially approximated a diastolic configuration but
about 20-40 minutes after injection went through a single final contraction over a time period of 5-10
minutes. This effectively slowed cardiac contraction by three orders of magnitude (from ~300 ms in vivo in
a beating heart to ~5 minutes) and allowed interrogation of contractile motion by DT-CMR in the absence
of cyclical strain effects. The hearts were then excised and imaged by ex vivo DT-CMR (N = 16) before
and after fixation. After that, tissue samples were obtained for paired histology (N = 16).
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Supplemental Figure 2. In situ imaging over ~1 hour after induction of cardiac arrest with KCl and
BaCl2. The KCl arrested hearts achieved their relaxed state immediately after injection and preserved it
throughout the one hour of in situ scanning. On the other hand, the BaCl2 arrested hearts started with a
relaxed configuration similar to that of the KCl arrested hearts, and approximately 20 minutes after
injection started contracting slowly (over a time period of ~10 minutes) until they achieved a systolic
configuration, which they preserved until the end of the ~1 hour scan.
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Supplemental Figure 3. Schematic description of histological cutting (top), and post-processing
(bottom). A block of tissue approximately 1cm x 1cm x wall thickness was cut from the lateral LV wall at a
mid-ventricular level (HA block). Two blocks either side of the HA block (long axis or LAX blocks) and two
blocks above and below the HA block (short axis or SAX blocks) were cut. Each block was processed for
paraffin embedded sections 10 microns thick. Sections for HA analysis were cut from the epicardial
surface to the endocardial surface of the HA block every 100-200 microns. The final number of HA slices
depended on the wall thickness of each sample. 10 slices 100 microns apart were produced from the LAX
and SAX blocks. All slices were stained using Masson staining. Both HA and LAX slices were registered
before edge detection. In the LAX slices, edge detection was only done in the mesocardial region with
circumferential cardiomyocytes, i.e., where cardiomyocytes are perpendicular to the slice. The orientation
of the edges was recorded and displayed in radial histograms.
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Supplemental Figure 4. Depiction of the projections of E1 and E2 and the corresponding E1A and
E2A. E1A is the angle between the projection of E1 and the circumferential axis (Panel A). E2A is the
angle between the projection of E2 and the wall tangential axis (Panel B). Transmural variation in E1 and
E2 (Panel C). Example low and high E2A (Panel D); a low E2A has a more wall-parallel orientation and a
high E2A has a more wall-perpendicular orientation.
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Supplementary Figure 5: Histograms of the transverse anisotropy (E3/E2 ratio) for all voxels. The
histograms represent the intersubject median and the interquartile range for all the cohorts in diastole and
systole.
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Supplemental Figure 6: Example b0 images, E1A maps, absolute E2A maps and signed E2A maps
in controls, HCM and DCM. The E1A maps show similar E1A distributions in all populations and
contractile states. The absolute E2A maps are color-coded such that low E2As close to 0° are blue, and
high E2As close to 90° are red. In the signed E2A maps, positive angles are red and negative angles are
green. The magnitude of the angle is indicated by the lightness, with small angles (close to 0°) shown in
light colors, and angles close to ±90° shown in black to reflect the equivalence of +90° and -90°.
Therefore, light pixels in the signed E2A maps should correspond to blue pixels in the absolute E2A
maps, and dark pixels in the signed E2A maps should correspond to red pixels in the absolute E2A maps.
In healthy controls, the diastolic absolute E2A maps display a preponderance of low absolute E2A (close
to 0°) in blue, which corresponds well with a preponderance of signed E2A angles close to 0° in light
colors in the signed E2A maps. The few patches of high absolute E2A (close to 90°) in red in the absolute
E2A maps match the few patches of signed E2A close to +90° or -90° in dark colors in the signed E2A
maps. In HCMs both the diastolic and the systolic absolute E2A maps are predominantly red (absolute
E2A close to 90°), and match the signed E2A maps that are predominantly dark (signed E2A close to
+90° or -90°). In DCM, both the diastolic and the systolic absolute E2A maps are predominantly blue
(absolute E2A close to 0°), and match with the signed E2A maps that are predominantly light (signed E2A
close to 0°).
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Supplemental Figure 7: Sketch of a helically twisted lazy tong mechanism. As the lazy tong
shortens, the angle between its struts decreases. As it opens, the angle between struts increases.
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Supplemental Figure 8. Plots of E1A against wall depth for controls, HCM and DCM patients, in
diastole and systole.
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