Japanese Journal of Applied Physics
Vol. 46, No. 7B, 2007, pp. 4889–4896#2007 The Japan Society of Applied Physics

Ultrasonic Imaging of Propagation of Contraction and Relaxationin the Heart Walls at High Temporal Resolution
Hiroki Y OSHIARA, Hideyuki HASEGAWA, Hiroshi KANAI, and Motonao T ANAKA1
Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
1
Tohoku Welfare Pension Hospital, Sendai 983-8512, Japan(Received November 24, 2006; revised March 6, 2007; accepted March 22, 2007; published online July 26, 2007)

Strain and strain rate imaging have been shown to be useful for the assessment of regional myocardial function. However,some of the mechanisms of transition in myocardial contraction/relaxation remain unclear. In this study, the RF echoes fromthe left ventricular (LV) wall were acquired in both the longitudinal-axis view and the apical view by scanning ultrasonicbeams sparsely to improve the temporal resolution, and a frame rate of about 600 Hz was realized. The phased tracking
method was applied to multiple points in the heart wall to estimate the strain rate. The spatial distribution of the strain ratemeasured about every 2 ms showed the continuous transition in the myocardium. In the apical view, the propagation speed ofcontraction from the apex to the base side in the interventricular septum was found to be about 0.8 m/s. These results indicate
the potential of this method in the estimation of the physiological function of the myocardium.
[DOI: 10.1143/JJAP.46.4889]
KEYWORDS: myocardial contraction/relaxation, strain rate, phased tracking method, frame rate, in vivo experiments

1.

Introduction

In recent years, there have been many studies on themeasurement of myocardial strain or strain rate, andtechniques for measuring them have been developed.
However, some of the mechanisms of the transition in
myocardial contraction/relaxation still remain unclear.
In conventional echocardiography, we can see mainly theshapes of organs and their slow motion with large amplitude.
In this case, the frame rate is, at most, 50 Hz, whichcorresponds to the sampling period of 20 ms.
For noninvasive measurement of the heart wall, tissue
Doppler imaging (TDI) has been developed.1–6) The TDI
technique enables the determination of the motion distribution in the myocardium in real time. In this method, theframe rate in TDI is limited to 200 Hz,1) corresponding to thesampling period of 5 ms. However, some transitions rapidly
occur during a short period of about 10 ms.7,8) Therefore, thecontinuous observation of such short transition requires aframe rate of more than 200 Hz. In this study, ultrasonicbeams were scanned sparsely so that the myocardial strain
rate could be measured in a wide area at a high temporal
resolution of about 1/600 s, particularly during the period
from the R-wave in the electrocardiogram (ECG) to thesecond heart sound in the phonocardiogram (PCG).
To improve the spatial resolution, Kanai et al. proposed
the phased tracking method which enables the detection ofsmall vibrations in the heart wall.9) This method was applied
to multiple points preset in the left ventricular (LV) wallalong an ultrasonic beam so that the spatial distribution ofvelocities at those points is simultaneously obtained.10,11)
Furthermore, this method was applied to other applications,such like the measurements of ultrasound backscatter12) andheart wall vibrations induced by external actuation.13) In thisstudy, the phased tracking method was applied to the points
assigned along the ultrasonic beam at smaller intervals thanthose in the previous studies10,11) to obtain a more continuous distribution of the myocardial strain rate along an
ultrasonic beam.
E-mail address: hkanai@ecei.tohoku.ac.jp

In addition, the LV wall was measured not only in thelong-axis view8) but also in the apical view. In vivo
experimental results in each scanned plane showed spatialtransition in myocardial contraction/relaxation. These results showed the possibility of applying this method in theelucidation of the mechanism of myocardial contraction/
relaxation.
2.

Principles

As illustrated in Fig. 1, both the interventricular septum(IVS) and posterior wall were measured. The RF data wereacquired using a 3.75 MHz sector-type probe of ultrasonicdiagnostic equipment (ALOKA SSD-6500). The sampling
frequency of the RF signal was 15 MHz. At time t ¼ t0 ,which is at the center of the assigned time period foranalysis, N layers with a thickness of d ¼ 821 mm wereassigned in the IVS from the right ventricular (RV) side to
RF acquisition area

RV
shift with ∆d/4=205 µm∆d=821 µm (layer thickness)

RV
Ao

IVS

LV

..
.

IVS

v ( x1i ; t )i-th layerLAultrasonicbeamv ( x2i ; t)..
.

posterior wallLV(b) t=t 0(a)RVi-th layer

IVS
LV

second heart soundPCG

t=t 0 –T

t=t 0

t=t 0 +T

time [s](c)Fig. 1. (a) RF signal acquisition in the parasternal longitudinal-axis viewof the LV. (b) Method of assigning layers along an ultrasonic beam at
t ¼ t0 . (c) Application of phased tracking method to the points preset in
the heart wall at t ¼ t0 .

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10 mm

10 mm

RV
RV

apical
side

Ao

LV
5

basal
side

LA

4
3

H. YOSHIARA et al.

LV IVS

RV
IVS

apex
side

Ao

35 ms

LA

LV

posterior wall
RF acquisition area

base
side

5
PW

beam 4
number 3(a) R-wave

2 1

beam number

2

1

decrease inthickness

Fig. 2. Cross-sectional image of the left ventricle in the long-axis view
obtained by conventional echocardiography for a healthy 22-year-old
male. The red arrows show the direction of the ﬁve ultrasonic beams used
for the estimation of strain rate in the IVS and posterior wall.

Si ðtÞ ¼

vðx2i ; tÞ  vðx1i ; tÞd[(m/s)/m];

ð2:1Þ

The numerator shows the diﬀerence between velocities at
the top and bottom points of the i-th layer, and thedenominator shows the initial thickness of the layer for
normalization. After the strain rates were estimated alongeach ultrasonic beam, they were superimposed on the Bmode image in every frame using a color code to obtain thetwo-dimensional (2-D) spatial distribution of the strain rate.
Blue indicates a thickening layer caused by myocardial
contraction, and red indicates a thinning layer caused bymyocardial relaxation. The strain rate of the posterior wall
was estimated as well as that of the IVS.
3.
3.1

In vivo Experimental Results

Transition from R-wave to second heart soundin long-axis view
Figure 2 shows a typical cross-sectional image (thetransthoracic parasternal longitudinal-axis view) of the heartobtained from a healthy 22-year-old male. The ﬁgure on theright-hand side of Fig. 2 shows the RF acquisition area. In
the acquisition of RF signals, the ultrasonic beam scans only
5 diﬀerent directions sparsely to maintain a high temporal
resolution. The frame rate was set to 630 Hz.
Figure 3 shows the two-dimensional distribution of strain
rate in the same subject as shown in Fig. 2 during thetransient period from contraction to relaxation. The bottom
graph shows the temporal change in the width of the LV
chamber along each ultrasonic beam. In the isovolmic
contraction phase [Fig. 3(b)], the basal side of the IVS
decreases in thickness, which corresponds to the extension

102 ms(d) Isovolmic
relaxation
Ao valve closure(d)(c)(c) Late ejection(a) (b)

ECG

PCG

42
width of LV chamber [mm]the LV side along an ultrasonic beam with intervals ofd=4 ¼ 205 mm. The thickness d was determined from theduration of an ultrasonic pulse transmitted from the probe.
Then, the phased tracking method was applied to both the
top x1i and the bottom x2i of the i-th layer (i ¼ 0; 1; 2; . . . ;N  1) to estimate velocities, vðx1i ; tÞ and vðx2i ; tÞ, for theperiod, t0  T  t  t0 þ T. Period T was set as short as
possible to avoid the inﬂuence of lateral motion of the heartwall,14) which is perpendicular to the ultrasonic beams.
We introduced the strain rate to evaluate how the
thickness of each layer changes with respect to time. Strain
rate Si ðtÞ of the i-th layer from the RV surface (i ¼ 0) at time
t is given by10)

increase inthickness(b) Isovolmic
contraction
246 ms

40
38
36

beam2
beam1
beam3

34
32
30

beam4
beam5

28
26
24
0

0.1

0.2

0.3
0.4
time [s]0.5

0.6

Fig. 3. Two-dimensional distribution of strain rate in the long-axis view
from the R-wave to the second heart sound for the same subject as inFig. 2. (a) Time of the R-wave. (b) Isovolmic contraction phase. (c) Lateejection phase. (d) Isovolmic relaxation phase. The bottom graph shows
the temporal change in the width of the LV chamber along each beam.

of the LV chamber at the basal area, as indicated by the redoval in the graph. This is considered to result from anincrease in the LV pressure upon contraction at the apicalarea for the succeeding ejection phase. Figures 3(b) and 3(c)show that the contraction extends gradually from the apicalarea to the basal area in the posterior wall. In addition, it isfound that the apical area of the posterior wall begins torelax in the late ejection phase [Fig. 3(c)]. In the isovolmic
relaxation phase [Fig. 3(d)] after aortic (Ao) valve closure,15) the posterior wall at the apical area relaxes rapidly,
which corresponds to the extension of the LV chamber at theapical area, as indicated by the black oval in the graph at thebottom of Fig. 3. This action is considered to cause thereduction of the LV pressure for the succeeding rapid ﬁllingphase. These preceding actions for the subsequent phases
probably contribute to the eﬃcient pump function of the left
ventricle.
3.2

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Transition from contraction to relaxation aroundsecond heart sound in long-axis view
Figure 4 shows the strain rate distribution in the myocar-

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H. YOSHIARA et al.

51 ms

R-waveapicalside
10 mmincrease inthickness

ECG

second heart sound

PCG

decrease inthickness

0

0.5Ao valve closure(a) 307 ms after R-wave
10 mm

IVS
LV

1.0 time [s](b)RF acquisition area

8
LA

RV

apex
side

IVS
1

(c)

IVS

beam
number

RV

LV

basal
side

LA

Ao

LV
base
side

PW

(d)

(e)

Fig. 5. Cross-sectional image of the left ventricle in the apical approachobtained by conventional echocardiography for a healthy 24-year-old
male. The arrows show the directions of the eight ultrasonic beams used
for estimating the strain rate distribution in the IVS.

(f)

10 mm
20 ms

(g)

(h)

apical side

depthelongation(i) Ao valve closure

40 ms(a) Strain ratebasal side

shortening

R-wave(b) ECG

delay from R-wave [ms]440

1st beat
2nd beat
3rd beat420(c) PCG400-70.0 mm/s
070.0 mm/s

380
360

(i)

340
51 ms

144 ms

320
(a)
300
5
apex side

4

3
beam number

2(d) velocity

1base side

Fig. 4. Strain rate distribution during transitional period from contraction
to relaxation every 6.3 ms around the second heart sound for the same
subject as in Figs. 2 and 3. The lower graph shows the delay time fromthe R-wave to the time when the LV-side of the posterior wall along eachultrasonic beam is closest to the LV chamber.

dium in the transitional period from contraction to relaxation
around the second heart sound every 6.3 ms in the long-axis
view. It is recognized that the relaxation occurs from thebasal area to the apical area in the IVS, and from the apicalarea to the basal area in the posterior wall. The transition
from contraction to relaxation was found to precede theaortic (Ao) valve closure.15) The bottom graph in Fig. 4
shows the delay time from the R-wave in the ECG to thetime at which the endocardial side of the posterior wall alongeach ultrasonic beam shows the maximum inward displacement in the LV chamber. Each delay graph for threeconsecutive cardiac cycles is overlaid. The movement of the
IVS and the posterior wall are away from and toward theprobe on the chest during the cardiac systole, respectively,
which shortens the LV chamber and causes blood to bepumped out.11) Therefore, the translation of the IVS and theposterior wall is considered to be negligible. As shown in thegraph, it was found that the apical area reaches the peaktoward the LV chamber earlier than the basal area. This

time [s]Fig. 6. Strain rate distribution in IVS along beam number 3 in Fig. 5
around R-wave. (a) Strain rate, Si ðtÞ, superimposed on M-mode image. (b)ECG. (c) PCG. (d) Superimposed estimates of velocity signals at multiple
points along the beam.

result corresponds to the transition in myocardial contraction/relaxation from the apical to the basal area in theposterior wall.
3.3

Transition at beginning of contraction in IVS aroundR-wave in apical approach
Figure 5 shows a cross-sectional image of the heart of ahealthy 24-year-old male examined by the apical approach.
For the acquisition of RF signals, 8 ultrasonic beams
scanned the IVS, realizing a high frame rate of 560 Hz. The
strain rate in the IVS was measured by the apical approach inorder to investigate the transition at the beginning ofcontraction in the IVS.
The strain rate distribution along each ultrasonic beam
was obtained by analyzing the region 144 ms (¼ 80
frames) around the R-wave in the ECG. Figure 6 shows thestrain rate distribution along beam number 3 in Fig. 5.
Figure 6(a) shows strain rate Si ðtÞ, deﬁned by eq. (2.1),
superimposed on the M-mode image using the color code on
the left-hand side of Fig. 6. Figures 6(b) and 6(c) show the
ECG and PCG, respectively. Figure 6(d) shows superim-

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apical (a)side
7.2 ms(b)
7.2 msH. YOSHIARA et al.

(c)apicalside

314 ms
RV

LA

R-wave

IVS
RV
LV

PCG

Ao

second heart sound13 ms time

basal
side

LV

apical side

ECG

LV

10 mm

Ao valve close

314 ms after R-wave

apicalside

elongation

PW

LA

Ao

basal sideelongationbasal side
7.2 ms

7.2 ms

10 mm(f)R-wave

(e)

(d)

7.2 msLV

shortening

basal side

shortening

(a)

IVS

(f)
R-waveECG

Q-waveFig. 8. Two-dimensional distribution of strain rate of IVS in apicalapproach every 1.8 ms around second heart sound for the same subject as
in Fig. 5.

PCG
144 mstime [s]Fig. 7. Two-dimensional distribution of strain rate in IVS in apicalapproach every 7.2 ms around R-wave for the same subject as in Fig. 5.
At (a) 36, (b) 29, (c) 22, (d) 14, and (e) 7 ms before the R-wave. (f) At thetime of R-wave.

posed estimates of the velocity signals at multiple points in
the IVS along the beam. In the apical approach, blue and redof the color code correspond to relaxation and contraction of
the myocardium, respectively. In Fig. 6(a), it is seen that thecontraction in the apical area precedes that in the basal areaby about 40 ms just before the R-wave.
Figure 7 shows the spatial distribution of the strain rate of
the IVS determined by the apical approach, around the Rwave for the same subject as shown in Figs. 5 and 6. It is
recognized that myocardial contraction extends graduallyfrom the apical area to the basal area just before the R-wave.
The propagation speed of the contraction was found to beabout 0.8 m/s. It is known that the propagation speed ofelectrically excited waves along the cardiac muscle is about
0.3 –1 m/s.16) Although the speed of the electrically excitedwave and that of the observed propagation of cardiac rapid
motion are in good agreement, the relationship between theelectrically excited wave and the observed propagation isstill unclear. The elucidation of this relationship requires
further investigation, particularly the analysis of the posterior wall in the apical view. The electrical signal isconducted along the Purkinje ﬁber in the myocardium,
which runs along the LV walls from the base side in the IVS
to the base side in the posterior wall via the apical area.16,17)
Therefore, the simultaneous observation of both the IVS andthe posterior wall in the apical view is needed to investigate
the myocardial transition along the Purkinje ﬁber to obtain
more information on this relationship. However, thismechanical contraction is found to occur around the Qwave in the ECG, which is known to be the time of

beginning of electrical excitation in the myocardium.17)
Therefore, this component is considered to be the ﬁrst
component of myocardial contraction in a cardiac cycle.
3.4

Transition at beginning of relaxation in IVS aroundsecond heart sound in apical approach
The spatial distribution of strain rate of the IVS around thesecond heart sound was obtained, as well as that around theR-wave. This period corresponds to the transient phase frommyocardial contraction to relaxation. Figure 8 shows thetransition from contraction to relaxation in the IVS aroundthe second heart sound for the same subject as shown in
Figs. 5–7. As seen in Fig. 8, myocardial relaxation occurs in
the middle of the IVS in the late contraction phase, which
extends gradually from the middle to both sides of the IVS.
3.5

Comparison of results of apical approachwith those in long-axis view
The results obtained by the apical approach werecompared with those in the long-axis view to conﬁrm thetransition of relaxation beginning from the middle of the IVS
in the late ejection phase. Figure 9 shows the spatial
distribution every 1.8 ms around the second heart soundfor the same subject (Fig. 5) in the long-axis view. This
period corresponds to that observed in Fig. 8. In the longaxis view, ultrasonic beams are almost perpendicular to
those in the apical approach. Therefore, blue and red in thelong-axis view correspond to contraction and relaxation,
respectively.
Although the lateral resolution is low in the long-axis
view in Fig. 9 because of the sparse scanning to achieve ahigh temporal resolution, the relaxation was found to extend
from the middle to both sides of the IVS, as in the apicalapproach shown in Fig. 8.

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298 msH. YOSHIARA et al.

13 ms

ECG
R-wave10 mm
Ao valve closure

apical
side

IVS

PCG

LV
second heart sound

0.5

0apicalside

apical sideelongation

Ao basalside

PW

time [s]RVLA

298 ms after R-wave

10mm

RV
LV

IVS

increase inthickness

basal
side

shortening

depth

middle30 msbasal side(a) Strain rate

decrease inthickness

R-wave(b) ECG(c) PCG-70.0 mm/s
070.0 mm/s (d) velocity
163 msFig. 9. Two-dimensional distribution of strain rate of IVS in long-axis
view at every 1.8 ms around second heart sound for the same subject as inFig. 5.

14

16

10 mm

RV

7 LV 10
1
4

Ao
10

LA

1 beam number

Fig. 10. Left: Cross-sectional image of left ventricle in apical approachobtained by conventional echocardiography for 79-year-old male with
OMI. The arrows show the directions of the 10 ultrasonic beams used forthe acquisition of RF signals in the IVS. Right: Segmentation in the apicallong-axis view.18)

4.

In vivo Experimental Results for Patient with Old
Myocardial Infarction

As an example of noninvasive diagnosis of the myocardium, we applied the proposed method to examine the IVSof a 79-year-old male patient with old myocardial infarction(OMI). Figure 10 shows a cross-sectional image of the heartin the apical long-axis view obtained from the patient andthe schematic of segmentation in the apical long-axis
view.18) In the acquisition of RF signals, the ultrasonicbeam scans 10 directions in the IVS and realizes a highframe rate of 490 Hz. During medical treatments, theinfarcted region was found in the antero septal region (#7),
as illustrated in Fig. 10.

time [s]Fig. 11. Strain rate distribution in IVS along beam number 5 in Fig. 10
around R-wave. (a) Strain rate, Si ðtÞ, superimposed on M-mode image. (b)ECG. (c) PCG. (d) Superimposed estimates of velocity signals at multiple
points along beam.

4.1 Analysis around R-wave in ECG
Beams 1-8 that scanned the IVS were analyzed. The strain
rate distribution along each ultrasonic beam was obtained byanalyzing the region 163 ms (¼ 80 frames) around the Rwave in the ECG. Figure 11 shows the strain rate distribution along beam number 5 in Fig. 10. Results shown in
Figs. 11(a)–11(d) correspond to those in Figs. 6(a)–6(d),respectively. From the strain rate distribution shown in
Fig. 11(a), it was found that the elongation (blue) in theatrium contraction phase before the R-wave is smaller thanthat in the healthy subject shown in Fig. 6(a). Althoughtransitional properties are similar to those for the healthy
subject, the depth at which the strain rate is small wasrecognized around the R-wave [white dashed oval in
Fig. 11(a)]. This region is further discussed in §4.3.
Figure 12 shows the spatial distribution of the strain rateof the IVS in the apical approach around the R-wave for thepatient. These results correspond to those for the healthy
subject shown in Fig. 7. It was found that myocardial
contraction extends gradually from the apical area to thebasal area just before the R-wave, as shown in Fig. 7.
However, the region near the apical area in the IVS shows asmall strain rate (grey zone), which is considered to result
from a decrease in the ability to contract actively in theinfarcted region.
4.2 Analysis around second heart sound in PCG
Figure 13 shows the transition from contraction torelaxation in the IVS around the second heart sound forthe same patient as shown in Fig. 10. Figure 13 shows thatthe transitional properties in myocardial relaxation are
similar to those of the healthy subject shown in Fig. 8.
Relaxation occurs in the middle of the IVS in the late4893

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H. YOSHIARA et al.

apical sideelongation
R-wave

ECG

LV
RV
PCG
time

45 ms

Ao LA
shortening

apicalside

basal side

10 mm

LV

basal side

R-waveFig. 12. Two-dimensional distribution of strain rate of IVS in apical approach every 4 ms around R-wave for same patient as in Fig. 10.

contraction phase, and extends gradually from the middle toboth sides of the IVS.
The region near the apical area, which is gray in Fig. 12,shows a smaller strain rate relative to that in the surroundingarea, but no deﬁnite diﬀerence was recognized around thesecond heart sound.
4.3

Average magnitudes of strain rates around R-wave
and second heart soundTo evaluate how each region in the IVS contracts/relaxes
in the transitional period, we adopted the average magnitudeof strain rate. Figure 14 shows color-coded images of
average strain rate in the periods around the R-wave in the
ECG and second heart sound in the PCG. Figure 14(a) shows
the average magnitude of strain rate for the period 82 ms(40 frames) around the R-wave. As shown in Fig. 14(c),the period around the second heart sound was analyzed aswell as that around the R-wave. These periods correspond to
the transitional period in myocardial contraction and relaxation. Figures 14(b) and 14(d) show the B-mode image at the
R-wave and that at the Ao valve closure, respectively. In
each period, two consecutive cardiac cycles were analyzed.

In Fig. 14(a), it was found that the region surrounded by
the white dashed line near the apical area in Fig. 14(b)shows a small average strain rate. This region corresponds to
the region where the propagation of contraction was notobserved in Fig. 12. This indicates that the thickness of theregion changes negligibly around the R-wave, which isconsidered to result from the decrease in the ability tocontract actively in the infarcted region.
As for the period around the second heart sound[Fig. 14(c)], the infarcted region was not clearly distinguished from the surrounding area. The infarcted area isconsidered to be passively stretched due to the ﬁlling of theleft ventricle with blood. Therefore, in the evaluation of the
myocardial function using the strain rate, it is useful toevaluate the strain rate in the period around the R-wave. In
this period, the mechanical reaction of the myocardium due
to electrical excitement can be sensitively evaluated fromthe strain rate.
4.4 Comparison of healthy subject with patient
As discussed in §4.3, the infarcted area was clearly
distinguished from the normal area in the period around the4894

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H. YOSHIARA et al.

280 mselongation

Ao valve close

apical side

ECG

R-waveRV

PCG
second heart sound

Ao LA

time

45 ms

LV

shortening

basal side

286 ms from R-wave
apical
side

10 mm

LV

basal side

Fig. 13. Two-dimensional distribution of strain rate of IVS in apical approach every 4 ms around second heart sound for same patient
as in Fig. 10.

R-wave. Here, the results of the patient are compared withthose of the healthy subject in the period around the R-wave.
Figure 15 shows the color-coded image of the averagemagnitude of strain rate for the period 82 ms around the Rwave. Figures 15(a) and 15(b) are the results for the healthy
subject shown in Fig. 5 and the patient with OMI shown in
Fig. 10, respectively. In Figs. 15(a) and 15(b), the crosssectional images were mirror images in the horizontal
direction, but almost the same areas in the IVS wereanalyzed.
Upon comparing Fig. 15(a) with Fig. 15(b), strain in thepatient is found to be smaller than that in the healthy subject
on the whole. In addition, a local region with a small change
in thickness was observed in the patient but not in thehealthy subject. These results indicate the possibility ofusing this method to quantitatively detect a locally infarcted
region in the myocardium.
5.

Conclusions

The spatial distribution of myocardial strain rate wasmeasured at an extremely high temporal resolution of aframe rate of about 600 Hz. From in vivo experimental
results in the long-axis view, it was found that the spatial
properties of myocardial contraction and relaxation vary

continuously. In particular, the transitional properties inmyocardial contraction/relaxation from the apical area tothe basal area were observed in the posterior wall. These
continuous transitions probably contribute to eﬃcient functioning of the human heart. In addition, the left ventricle wasmeasured not only in the long-axis view but also by the
apical approach. The spatial distribution of the strain rate of
the IVS in the apical approach showed transitions of
myocardial contraction and relaxation in the IVS and theposterior wall. These results indicate the possibility of using
this method for the elucidation of the mechanism of
myocardial contraction and relaxation.
In addition, this method was applied to a patient with
OMI. It was found that the infarcted area could clearly be
distinguished from a normal area in the period around the Rwave in the ECG. This result indicates the possibility ofusing this method for noninvasive diagnosis of the myocardium, particularly the detection of a locally infarcted region
in the myocardium, which is diﬃcult to detect using theECG.19)Acknowledgements
The authors are grateful to associate professor Yoshifumi
Saijo of Institute of Development, Aging and Cancer,

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+ 82 msaround the R-wave

ECG

R-waveECG
R-wave+ 82 msPCG
0.5 time [s]0(a) normal subject(b) old myocardial infarction

second beatfirst beataverage of magnitudeof strain ratetime

B-mode image
at R-wave

LV

LV

(a-1)

(b-1)

around the second heart sound

(a-2)

(b-2)

R-wave+ 82 ms

LV

Ao valve close

ECG

second heart sound

6)
7)
8)
(d-1)

LV

Ao
Ao

LA

basal side

Fig. 15. Average magnitudes of strain rates of the healthy subject and thepatient in the period 82 ms around R-wave in ECG. (a) Healthy subject
as in Fig. 5. (b) Same patient with old myocardial infarction as in Fig. 10.

5)

(c-1)

LA

basal side

0.5 time [s]second beatfirst beataverage of magnitude B-mode image
at Ao valve closureof strain rate

RV
RV

PW
PCG
0

apical side

apical side

(c-2)

(d-2)

9)

Fig. 14. Two-dimensional distribution of average magnitude of strain ratearound R-wave and second heart sound. (1) First heart beat. (2) Second
heart beat. (a) Average magnitude of strain rate for the period 82 ms
around R-wave. (b) B-mode image at R-wave. (c) Average magnitude ofstrain rate for the period 82 ms around Ao valve closure (second heartsound). (d) B-mode image at Ao valve closure.

10)
11)
12)
13)

Tohoku University, and Dr. Sachiko Watanabe of Tohoku
University Hospital for helpful discussion and assistancewith experiments.

14)

15)
16)

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