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The effects on left and right ventricular (LV, RV) volumes during physical exercise remains controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV and total heart volumes (THV) as well as cardiac pumping mechanisms change during physical exercise compared to rest using cardiovascular magnetic resonance (CMR). 26 healthy volunteers (6 women) underwent CMR at rest and exercise. Exercise was performed using a custom built ergometer for one-legged exercise in the supine position during breath hold imaging. Cardiac volumes and atrio-ventricular plane displacement were determined. Heart rate (HR) was obtained from ECG. HR increased during exercise from 60+/-2 to 94+/-2 bpm, (p<0.001). LVEDV remained unchanged (p=0.81) and LVESV decreased with -9+/-18% (p<0.05) causing LVSV to increase with 8+/-3% (p<0.05). RVEDV and RVESV decreased by -7+/-10% and -24+/-14% respectively, (p<0.001) and RVSV increased 5+/-17% during exercise although not statistically significant (p=0.18). Longitudinal contribution to RVSV decreased during exercise by -6+/-15% (p<0.05) but was unchanged for LVSV (p=0.74).THV decreased during exercise by -4+/-1%, (p<0.01) and total heart volume variation (THVV) increased during exercise from 5.9+/-0.5% to 9.7+/-0.6% (p<0.001). Cardiac volumes and function are significantly altered during supine physical exercise. THV becomes significantly smaller due to decreases in RVEDV whilst LVEDV remains unchanged. THVV and consequently radial pumping increases during exercise which may improve diastolic suction during the rapid filling phase.
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R E S E A R C H Open Access
Moderate intensity supine exercise causes
decreased cardiac volumes and increased outer
volume variations: a cardiovascular magnetic
resonance study
Katarina Steding-Ehrenborg
1,2
, Robert Jablonowski
3
, Per M Arvidsson
3
, Marcus Carlsson
3
, Bengt Saltin
1
and Håkan Arheden
3*
Abstract
Background: The effects on left and right ventricular (LV, RV) volumes during physical exercise remains
controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution
to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV
and total heart volumes (THV) as well as cardiac pumping mechanisms change during physical exercise compared
to rest using cardiovascular magnetic resonance (CMR).
Methods: 26 healthy volunteers (6 women) underwent CMR at rest and exercise. Exercise was performed using a
custom built ergometer for one-legged exercise in the supine position during breath hold imaging. Cardiac
volumes and atrio-ventricular plane displacement were determined. Heart rate (HR) was obtained from ECG.
Results: HR increased during exercise from 60±2 to 94±2 bpm, (p<0.001). LVEDV remained unchanged (p=0.81)
and LVESV decreased with 9±18% (p<0.05) causing LVSV to increase with 8±3% (p<0.05). RVEDV and RVESV
decreased by 7±10% and 24±14% respectively, (p<0.001) and RVSV increased 5±17% during exercise although
not statistically significant (p=0.18). Longitudinal contribution to RVSV decreased during exercise by 6±15%
(p<0.05) but was unchanged for LVSV (p=0.74). THV decreased during exercise by 4±1%, (p<0.01) and total heart
volume variation (THVV) increased during exercise from 5.9±0.5% to 9.7±0.6% (p<0.001).
Conclusions: Cardiac volumes and function are significantly altered during supine physical exercise. THV becomes
significantly smaller due to decreases in RVEDV whilst LVEDV remains unchanged. THVV and consequently radial
pumping increases during exercise which may improve diastolic suction during the rapid filling phase.
Keywords: Physiology, Total heart volume variation, Ventricle, Cardiac pumping, Cardiovascular magnetic resonance
Background
Total heart volume at rest has a strong correlation to
peak exercise capacity in healthy normal subjects and
athletes [1,2]. When going from rest to exercise the nor-
mal heart in a sedentary individual can increase its cardiac
output from 5 L/min to 2025 L/min [3]. This change has
been attributed to an increase in heart rate and stroke
volume. In turn, the stroke volume can increase either by
an increase in end-diastolic volume (EDV), decrease in
end-systolic volume (ESV), or both. The effects on left
ventricular (LV) volumes during physical exercise remain
controversial. Previous studies using radionuclide angiog-
raphy or echocardiography have shown both unchanged
and increased LV end-diastolic volumes (LVEDV) during
upright and supine exercise compared to resting values
in the same position [4-12]. Although most studies show
a decrease in ESV during exercise, Sundstedt et al. [12]
showed unchanged ESV during supine exercise using
echocardiography. Few studies have investigated the
* Correspondence: hakan.arheden@med.lu.se
3
Department of Clinical Physiology, Lund University, Lund University Hospital
Lund, Lund, Sweden
Full list of author information is available at the end of the article
© 2013 Steding-Ehrenborg et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96
http://jcmr-online.com/content/15/1/96
effects of exercise on the right ventricle [13,14] and further
studies are needed to understand how physical exercise af-
fects left and right cardiac volumes and subsequently the
stroke volume (SV).
Ventricular stroke volume is ejected by a combination
of longitudinal and radial contraction of the ventricle
[15-18]. At rest the longitudinal contribution to SV has
been shown to be 60% for the LV and 80% for the RV
and radial contribution is 40% and 20% respectively
[15,17,19]. It has been shown that during exercise there
is a significant increase in the mitral valve displacement
during exercise [20]. Longitudinal pumping is calculated
as the atrio-ventricular plane displacement (AVPD) multi-
plied by the short-axis area of the ventricle and an increase
in AVPD may therefore affect the longitudinal contribu-
tion to SV. Several studies have suggested that at higher
heart rates a larger longitudinal contribution may keep the
outer volume variation of the heart to a minimum render-
ing less energy to be wasted on moving surrounding tis-
sues [21-23]. However, this remains to be explored.
Therefore, the aim of this study was to determine left
and right ventricular volumes, left and right atrial vol-
umes and total heart volumes as well as longitudinal and
radial pumping during rest and physical exercise using
cardiovascular magnetic resonance (CMR).
Methods
This study was approved by the Regional Ethical Review
Board in Lund, Sweden and follows the Declaration of
Helsinki. All participants provided written informed con-
sent. All CMR examinations were performed at Skane
University Hospital Lund, Sweden.
Study population and experimental setup
Twenty-six healthy volunteers (six women) aged 30±8 years
(mean±SD) (range 1959) underwent CMR at rest and
during exercise with one-legged knee extensions. A custom
built MR-compatible ergometer provided concentric re-
sistance during knee extension by a rope and pulley sys-
tem which was integrated with a mechanically braked
flywheel. A strap connected to a variable weight system
provided resistance and weight was added to achieve an
exercise level at approximately 40 beats per minute
(bpm) higher than the subjectsresting heart rate. The
subjects were connected at the ankle to the axle of the
flywheel by a rope and the extension phase of the exer-
cise turned the flywheel. Gravity returned the leg to the
starting position and a gearing system on the axle
returned the rope to the starting position at the end of
each duty cycle.
Reproducibility of exercise measurements
Six subjects underwent a total of five CMR scans to in-
vestigate the reproducibility of volumetric measurements
during exercise and the potential effects of different re-
spiratory phases as well as differences in exercising muscle
mass. The scans were divided into two sessions with a
1.5 hour rest outside the scanner between them. Session 1
included a) CMR at rest; b) CMR with 1-legged exercise
at end-expiratory breath hold; and c) CMR with 2-legged
exercise at end-expiratory breath hold. Session 2 in-
cluded a) CMR with 1-legged exercise at end-expiratory
breath hold; and b) CMR with 1-legged exercise at end-
inspiratory breath hold with the instructions to keep an
open glottis and avoid Valsalva-like increases in intra-
thoracic pressures.
Cardiac magnetic resonance imaging
A 1.5T scanner (Philips Achieva, Philips, Best, The
Netherlands) with a 5 channel cardiac coil was used to
scan all subjects in the supine position. A balanced
steady-state free-precession (bSSFP) sequence with
retrospective ECG gating was used to acquire images of
the heart (repetition time typically 3.0 ms, turbo factor
16, echo time 1.5 ms, flip angle 60°, reconstructed to a
spatial resolution of 1.4 × 1.4 mm, acquired temporal
resolution typically 50 ms reconstructed to 30 ms, and
slice thickness 8 mm with no slice gap). After defining
the long-axis orientation of the heart, short-axis images
covering the heart from the base of the atria to the apex
of the ventricles were obtained. Breath-hold during
imaging during exercise was typically 6 s for long-axis
images and 810 s for each short-axis slice. An ECG-
triggered phase-contrast sequence was used to measure
blood flow in the aorta (repetition time 8.6 ms, echo
time 6.4 ms, 150 cm/s velocity encoding, slice thickness
8 mm). The measurement plane was positioned perpen-
dicular to the vessel. Heart rate was obtained from the
ECG during image acquisition.
Atrial and ventricular volumes
All measurements were done using the software Segment
1.8 (http://segment.heiberg.se) [24]. Left and right atrial
volumes were measured in short-axis images at the time of
ventricular end-diastole and ventricular end-systole. Left
ventricular mass (LVM), end-diastolic volume (LVEDV),
end-systolic volume (LVESV) and stroke volume (LVSV)
were measured in short-axis images using planimetry, by
manual delineation of endocardial and epicardial borders
of the left ventricle. Papillary muscles were not included in
LVM measurements. Right ventricular end-diastolic vol-
ume (RVEDV), end-systolic volume (RVESV) and stroke
volume (RVSV) were measured in short-axis images by
manual delineation of the right ventricular endocardial and
epicardial border.
Total heart volume (THV) was measured in short-axis
images by planimetry [22] and was defined as the vol-
ume of all structures within the pericardium, including
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96 Page 2 of 8
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myocardium, blood pool, atria, pericardial fluid and the
proximal parts of the great vessels.
Ventricular pumping
Atrio-ventricular plane displacement (AVPD) was deter-
mined from CMR long-axis images as previously de-
scribed [15]. Longitudinal pumping of the left and right
ventricle was calculated as the distance travelled by the
AV-plane multiplied by epicardial short-axis area of the
ventricle [25]. Radial pumping was determined from the
total heart volume variation (THVV) [15]. Longitudinal
and radial contribution to SV (%) was calculated as lon-
gitudinal pumping divided by SV and radial pumping di-
vided by SV.
Statistical analysis
Statistical analysis was performed using SPSS statistics
20 (IBM, Chicago, IL, USA) and a p-value <0.05 was
considered statistically significant. Paired t-tests were used
to test for changes between rest and exercise. Wilcoxon
non-parametric test was used to test for differences be-
tween rest and exercise in the subgroup of six subjects
who underwent a total of five scans to investigate the re-
producibility of measurements. Results are presented as
mean ±SEM unless stated otherwise. Inter-observer vari-
ability was determined for the left ventricular measure-
ments in ten subjects during rest and exercise.
Results
Subject characteristics are presented in Table 1. All sub-
jects reported to be healthy and none of the subjects
showed any signs of cardiac disease on the CMR scan.
In three subjects the same short-axis slice was imaged
twice due to difficulties in breath holding during exer-
cise. These extra slices were identified and removed be-
fore the images were analysed. Figure 1 and Additional
files 1, 2, 3 and 4 show typical examples of the image
quality during exercise.
Heart rate and cardiac volumes
Heart rate increased significantly during exercise from
60±2 to 94±2 bpm (p<0.001). Left atrial volumes at end-
diastole decreased from 39±3 to 35±3 mL (p<0.05) as did
right atrial end-diastolic volumes from 65±5 to 56±4 mL
(p<0.05). At ventricular end-systole, where the atria reach
their largest volumes, left atrial volumes were unchanged
(84±4 and 85±5 mL, p=0.72) and right atrial volume de-
creased significantly from 124±7 to 103±7 mL (p<0.001)
with exercise.
Left ventricular EDV remained unchanged during ex-
ercise (186±8 to 185±8 mL, p=0.81) and LVESV de-
creased from 82±4 to 74±4 mL (p<0.05) (Figure 2A-B).
Left ventricular SV increased from 104±4 to 111±5 mL
(p<0.05, Figure 2C). For the right ventricle, both RVEDV
and RVESV decreased from 203±9 to 185±10 mL for
RVEDV and from 100±6 to 77±6 mL for RVESV
(p<0.001 for both) (Figure 2D-E) but the increase in
right ventricular SV from 104±4 to 108±5 mL was not
significant (p=0.18) (Figure 2F). Both left and right ven-
tricular ejection fraction (LVEF and RVEF) increased dur-
ing exercise from 56±1 to 60±1% and from 52±1 to 59±1%
respectively (p<0.01 for both). Cardiac output increased
from 6.2±0.3 to 10.4±0.5 L/min (p<0.001) mainly due
totheincreaseinheartrate(Figure3A-B).Interest-
ingly, total heart volume decreased significantly during
exercise by 30±8 mL, (p<0.01) corresponding to a 4±1%
decrease of volume (example shown in Figure 4 and in
Additional file 4). As expected, LVM was unchanged from
rest to exercise (115±6 to 114±6 g, p=0.62).
Left and right atrio-ventricular plane displacement
Left ventricular AVPD and RVAVPD remained unchanged
during exercise. Left ventricular AVPD was 14.6±0.3 mm
at rest and 15.3±0.5 mm during exercise (p=0.06) and
the RV AVPD was 20.9±0.6 mm for both rest and ex-
ercise (p=0.90).
Longitudinal and radial pumping
Left ventricular longitudinal contribution to SV (%)
remained unchanged at approximately 60% (59±1% at
rest and 60±2% at exercise, p=0.74). Right ventricular
longitudinal contribution (%) decreased from 81±2 to
75±2% (p<0.05) (Figure 5A-B) due to the decrease in
RV end-diastolic volume. Total heart volume variation
increased during exercise from 5.9±0.5 to 9.7±0.6%
(p<0.001) (Figure 5C).
Table 1 Subject characteristics and cardiac volumes at
rest for men and women (mean±SD)
Men n=20 Women n=6
Age (years) 30±9 29±8
Weight (kg) 78±12 61±14
Height (m) 1.80±0.07 1.68±0.07
THV (mL) 861±145 586±123
LVEDV (mL) 197±34 148±36
RVEDV (mL) 219±37 149±39
LVSV (mL) 109±19 87±22
RVSV (mL) 110±17 84±23
LVM (g) 126±22 79±17
LAes (mL) 89±19 65±24
RAes (mL) 134±33 90±22
g = gram, kg = kilogram, LAes = left atrial volume measured at ventricular
end-systole, LVEDV = left ventricular end-diastolic volume, LVM = left ventricular
mass, LVSV = left ventricular stroke volume, m = metre, mL = millilitre,
RAes = right atrial volume measured at ventricular end-systole, RVEDV = right
ventricular end-diastolic volume, RVSV = right ventricular stroke volume,
THV = total heart volume, THVV = total heart volume variation.
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96 Page 3 of 8
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Reproducibility of exercise measurements
For the six subjects participating in repeated scans there
were no differences in THV, RVEDV or left and right SV
between the first and second exercise session with one
leg. Left ventricular EDV increased more during the
second exercise session when compared to rest; a 5±5%
increase during the first session and a 11±4% increase
during the second session (p<0.05). When comparing end-
expiratory breath hold with end-inspiratory breath hold,
only LVEDV differed between sessions. When compared
Figure 1 Short-axis images showing the typical image quality during exercise. These images were acquired at a heart rate of 119 bpm. The
top left image shows the most basal short-axis slice showing the roof of the atria and the bottom right image shows the most apical slice of the
ventricles. Ao aorta, LA left atrium, LV left ventricle, Pulm pulmonary trunk, RA right atrium, RV right ventricle.
Figure 2 Left and right ventricular volumes and stroke volumes at rest and exercise. Upper panel shows no changes in left ventricular
end-diastolic volumes (A) and a small but significant decrease in end-systolic volume (B), leading to an increased stroke volume (C). Lower panel
show a significant decrease in right ventricular end-diastolic volume (D) and end-systolic volume (E). Right ventricular stroke volume increased
during exercise, however not statistically significant (F). Error bars denote mean and standard error of the mean (SEM).
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96 Page 4 of 8
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to rest there was a 5±5% increase at end-expiratory
breath hold and a 15±7% increase at end-inspiratory
breath hold (p<0.05). During exercise using two legs,
left and right ventricular EDV did not differ when com-
pared to one-legged exercise. Left ventricular EDV in-
creased by 5±5% and 7±7% respectively (p=0.35), and
RVEDV decreased by 4±6% and 2±7% respectively
(p=0.17). Right ventricular SV, however, increased more
during exercise using two legs. When compared to rest the
increase was 3±10% with one leg and 12±9% with two legs.
Inter-observer variability and validation
Results are presented as mean ±SD. At rest, inter-
observer variability for LVM was 9±5 g, EDV 1±4 mL
and SV 2±5 mL. During exercise imaging was more
difficult and the image quality was lower, which is
reflected by a slightly larger variability; LVM 7±10 g,
EDV 3±16 mL and SV 0±9 mL.
Discussion
The present study has shown that the total heart vol-
ume decreases in healthy normal subjects during
moderate exercise in the supine position. This de-
crease is caused by reduced right atrial and ventricu-
lar volumes whilst left atrial and ventricular volumes
remain unchanged during exercise. With regards to
pumping function there is an increase in outer vol-
ume changes during exercise and thus, an increased
radial contribution to stroke volume. AV-plane move-
ment is unchanged during exercise but a smaller
short-axis area of the right ventricle causes the lower
longitudinal contribution to RVSV. Left ventricular
longitudinal contribution to SV is unchanged during
exercise. Total left and right ventricular SV were only
slightly increased (LVSV) or unchanged (RVSV) dur-
ingsupineexerciseandtheincreaseincardiacoutput
is best explained by the rise in heart rate.
Figure 3 Heart rate and cardiac output at rest and exercise. Heart rate (A) and cardiac output (B) increased significantly from rest to
exercise. Error bars denote mean and standard error of the mean (SEM).
Figure 4 Mid-ventricular short axis slices in end-diastole (ED) and end-systole (ES) during rest and exercise with the corresponding
4-chamber (4 ch) view to illustrate the location of the slice. The solid line indicates delineations for total heart volume. In the exercise
images, the dashed line shows the total heart volume delineation copied from the corresponding resting image. The right ventricular volume is
decreased whereas the left ventricle remains unchanged.
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96 Page 5 of 8
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Ventricular volumes and stroke volume
The inconsistent results of previous studies [4-7,11,12,14,26]
may be explained by differences in imaging modalities
and, perhaps most important, body position. The results
of this study are in line with other studies of supine exer-
cise showing unchanged LVEDV [5,9,10,27,28]. The sig-
nificant decrease in RVEDV differs from previous studies
of RV volumes during supine exercise using radionuclide
ventriculography [13] and CMR [14,28] where RVEDV
remained unchanged during moderate intensity exercise
(mean HR in these studies were 112,120 and 100 bpm re-
spectively). However, in line with our results the study by
Mols et al. [13] used radionuclide ventriculography and
showed a decreased RVEDV at workloads at a HR of
127 bpm and above. The differences between the present
study and previous CMR studies may be explained by dif-
ferences in exercise protocol where we acquired breath-
hold images during leg exercise whilst Holverda et al. [28]
used non-breath hold imaging and Roest et al. [14]
allowed the subjects to rest for the short period of image
acquisition. Free-breathing may decrease image quality
and rest during image acquisition will allow HR to de-
crease making interpretation of results more difficult.
In line with studies by Bevegård et al. [29] the present
study showed that CO increased significantly due to in-
creased HR whilst SV only increased by 8%. During the
early stages of exercise in healthy subjects, the increase in
HR is primarily caused by a decreased parasympathetic
tone whereas the sympathetic effects are not seen until
later stages [30]. As the exercise bouts of the study were
short, the increased HR with only a small increase in SV is
likely caused by parasympathetic withdrawal. Further-
more, the increased venous return caused by the supine
position lead to maximal filling of the ventricles already at
rest, which would explain the discrepancy between our
study and exercise studies performed in the upright pos-
ition. Our study would then be more representative of ex-
ercise in the supine position such as swimming or perhaps
in micro gravitational environments such as space flight.
Longitudinal and radial contribution to stroke volume
In contrast to a previous study of upright exercise on an
ergometer cycle where the left ventricular valve displace-
ment was significantly increased during exercise [20],
our results showed unchanged LV AVPD and longitudinal
contribution to LVSV. Right ventricular valve displace-
ment (RV AVPD) remained unchanged but together with
the decreased volume of the right ventricle, the right ven-
tricular longitudinal contribution to SV was significantly
decreased. Furthermore, total cardiac pumping became
significantly more radial during exercise as shown by the
increased THVV when exercising both with one and two
legs, as well as during end-expiratory and end-inspiratory
breath hold. This is in contrast to a hypothesis previously
suggested by our group [22] where we expected cardiac
longitudinal pumping to increase and radial pumping to
decrease. Increased radial pumping as seen in the present
study may theoretically increase the amount of energy
spent on moving surrounding tissues and thus decrease
the energy efficiency of the heart. However, for the left
ventricle, Riordan and Kovács [31] showed that radial
pumping may actually be important for diastolic suction
during the rapid filling phase. Exercise requires rapid mass
transfer from the atria to the ventricle, and it is possible
that the increased radial pumping seen in the right ven-
tricle may actually improve cardiac pumping efficiency
due to enhanced diastolic suction.
It is possible that our findings of increased THVV only
relates to exercise in the supine position such as swim-
ming, and it would be of interest to perform similar
studies during upright exercise.
Reproducibility of exercise measurements
Ventricular volumes and THV were reproducible between
the first and second exercise session, and also when im-
aging was performed at end-inspiratory breath hold as
well as during exercise with two legs. The differences seen
in LVEDV between the first and second exercise session
with one leg as well as between end-expiratory and end-
Figure 5 Longitudinal and radial contribution to stroke volume at rest and exercise. Left ventricular longitudinal contribution increased
(A) whereas the right ventricular contribution decreased (B). Total radial contribution calculated as total heart volume variation THVV (C) increased
significantly indicating an overall increase in radial pumping of the heart during exercise. Error bars denotes mean and standard error of the
mean (SEM).
Steding-Ehrenborg et al. Journal of Cardiovascular Magnetic Resonance 2013, 15:96 Page 6 of 8
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inspiratory breath hold is probably best explained by indi-
vidual variations that are more distinguishable in the small
population. As shown in Figure 2 there is some variability
between individuals for all variables and when only asses-
sing six subjects results may fall out as statistically signifi-
cant although not physiologically relevant.
Clinical implication
Heart failure is a complex syndrome and diagnosis can
be especially challenging at early stages. Cardiac MR
during physical exercise may become useful for assessing
patients with normal ejection fraction and suspected
heart failure to investigate if cardiac function and filling
are affected during low and medium intensity exercise.
Furthermore, exercise CMR may also be used to asses
patients with congenital heart disease such as Tetralogy
of Fallot before and after surgery.
Limitations
Exercise heart rate in our healthy volunteers only in-
creased by approximately 40 bpm over resting HR and it
is possible that a higher exercise HR may yield different
results. The study population included to test for repro-
ducibility of exercise measurements was small (n=6) and
the results of the statistical tests of this subpopulation
on reproducibility should be interpreted with caution.
Furthermore, the study was performed in the supine
position limiting the interpretation of our results to su-
pine exercise such as swimming, but it may also be ap-
plicable for conditions of microgravity, such as space
flight.
Conclusions
Moderate intensity exercise in the supine position sig-
nificantly decreases the total heart volume. This is due
to decreases in right atrial and ventricular volumes at
end-diastole whilst the LVEDV remains unchanged. The
contribution of longitudinal pumping to stroke volume
is unchanged in the left ventricle but decreased in the
right ventricle in exchange for an increase in radial
pumping. In contrast to previous belief, THVV and con-
sequently radial pumping increases which may improve
diastolic suction of the ventricles.
Additional files
Additional file 1: Short-axis image of a healthy heart during
exercise at a heart rate of 108 bpm.
Additional file 2: Two-chamber long-axis view of a healthy heart
during exercise at a heart rate of 102 bpm.
Additional file 3: Three-chamber long-axis view of a healthy heart
during exercise at a heart rate of 117 bpm.
Additional file 4: Four-chamber long-axis view of a healthy heart
during exercise at a heart rate of 124 bpm.
Competing interests
The authors declared that they have no competing interest.
Authorscontributions
KSE: Conception of study, data inclusion and analysis, interpretation of data,
drafting and revising the manuscript. RJ: Data inclusion and critical revision
of the manuscript. PMA: Data inclusion and analysis, critical revision of the
manuscript. MC: Conception of study, data inclusion and critical revision of
the manuscript. BS: Conception of study, construction of MR ergometer,
critical revision of manuscript. HA: Conception of study, critical revision of
manuscript. All authors read and approved the final manuscript.
Acknowledgement
The authors wish to thank FlemmingJessen at the Copenhagen Muscle
Research Centre for design and construction of the ergometer and Ance
Kreslin for help with data collection and analysis. This study was supported
by the Swedish Research Council, the Swedish Heart and Lung Foundation,
Region of Scania, the Medical Faculty at Lund University, Sweden, the
Swedish Heart Association and Novo Nordisk Foundation, Denmark.
Author details
1
Copenhagen Muscle Research Centre, Copenhagen, Denmark.
2
Danish
Research Centre for Magnetic Resonance, Hvidovre Hospital, Copenhagen,
Denmark.
3
Department of Clinical Physiology, Lund University, Lund
University Hospital Lund, Lund, Sweden.
Received: 26 April 2013 Accepted: 1 October 2013
Published: 24 October 2013
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doi:10.1186/1532-429X-15-96
Cite this article as: Steding-Ehrenborg et al.:Moderate intensity supine
exercise causes decreased cardiac volumes and increased outer volume
variations: a cardiovascular magnetic resonance study. Journal of
Cardiovascular Magnetic Resonance 2013 15:96.
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... Excessive motion during exercise however poses a challenge in image acquisition. As a result, investigators have resorted to acquire images following transient cessation of exercise (17), during breath-holds (6,17,18) or using ungated real-time cine imaging (19). Reconstruction of a short axis stack for volumetric analysis from ungated realtime imaging, however, involves complex post-processing analysis in addition to a requirement for bespoke in-house software (19). ...
... Previously, image acquisition techniques using the MRI cycle ergometer have either involved a brief period of exercise cessation (17) or required a breath-hold protocol (6,18) in order to reduce excessive motion artefacts and avoid poor ECG signal. Ungated real-time CMR imaging (19,23,24) has been a method that enabled cine images to be acquired during continuous exercise. ...
... The results of this present study are in line with previous studies of supine exercise, showing a decrease in LV (24,36) and RV (18,23,37) EDVs, particularly during later stages of exercise. Similar to previous exCMR studies, we demonstrated no significant rise in stroke volume with exercise (38). ...
Article
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Background: Cardiovascular magnetic resonance (CMR) image acquisition techniques during exercise typically requires either transient cessation of exercise or complex post-processing, potentially compromising clinical utility. We evaluated the feasibility and reproducibility of a navigated image acquisition method for ventricular volumes assessment during continuous physical exercise. Methods: Ten healthy volunteers underwent supine cycle ergometer (Lode) exercise CMR on two separate occasions using a free-breathing, multi-shot, navigated, balanced steady-state free precession cine pulse sequence. Images were acquired at 3-stages, baseline and during steady-state exercise at 55% and 75% maximal heart rate (HRmax), based on a prior supine cardiopulmonary exercise test. Intra-and inter-observer variability and inter-scan reproducibility were derived. Clinical feasibility was tested in a separate cohort of patients with severe mitral regurgitation (n=6). Results: End-diastolic volume (EDV) of both LV and RV decreased during exercise at 55% and 75% HRmax, although a reduction in RVEDV index was only observed at 75% HRmax. Ejection fractions (EF) for both ventricles were significantly higher at 75% HRmax compared to their respective baselines (LVEF 68%±3% vs. 58%±5%, P=0.001; RVEF 66%±4% vs. 58%±7%, P=0.02). Intra-observer and inter-observer reproducibility of LV parameters was excellent at all 3-stages. Although measurements of RVESV were more variable during exercise, the reproducibility of both RVEF and RV cardiac index was excellent (CV <10%). Inter-scan LV and RV ejection fraction were highly reproducible at all 3 stages, although inter-scan reproducibility of indexed RVESV was only moderate. The protocol was well tolerated by all patients. Conclusions: Exercise CMR using a free-breathing, multi-shot, navigated cine imaging method allows simultaneous assessment of left and right ventricular volumes during continuous exercise. Intra- and inter-observer reproducibility were excellent. Inter-scan LV and RV ejection fraction were also highly reproducible.
... Studies utilising commercially produced cycle ergometers followed in 1998 with the use of the Lode BV MR compatible ergometer (Fig. 3) on a 1.5 T CMR scanner [60]. Whilst the majority of Ex-CMR cycle ergometer studies use this system [29,54,55,, some institutions have created custom made CMR compatible cycle ergometers [25,81,82]. Other approaches include the supine CMR compatible 'stepper' ergometer, that utilises an up/down motion, such as the Lode BV up/down ergometer [83][84][85], Ergospect cardio-stepper [86] and custom built supine steppers as demonstrated in Fig. 4 [87]. ...
... Cycle ergometer Ex-CMR ventricular volume assessment has progressed from imaging during exercise cessation with breath holding [25,67,[70][71][72]81], breath holding during exercise [82,86], free breathing with exercise cessation [54,64,66], to free breathing during continuous exercise [29,83]. Initial studies utilised turbo field echo planar imaging (EPI) with retrospective gating to acquire short axis cine imaging for biventricular volumes during exercise [67,70,71]. ...
... Initial studies utilised turbo field echo planar imaging (EPI) with retrospective gating to acquire short axis cine imaging for biventricular volumes during exercise [67,70,71]. Subsequent studies using retrospective ECG gating have used balanced steady state free precision (bSSFP) sequences [25,81,82,88,89]. Recently, an Ex-CMR study used a 3 T scanner to assess LV volumes similarly used bSSFP sequences to acquire 4 chamber and 2-chamber cines to calculate LV function via Simpson's bi-plane method [86]. ...
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Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.
... In addition, despite the presence of observations regarding the effect of alterations in heart rate on LV volumes, these studies were done mainly among men and did not provide viable information on the effect of heart rate increase on heart chamber volumes among women. [2][3][4][11][12][13][14][15][16][17][18] CCTA is nowadays widely used for the assessment of CAD. 19 The same imaging study may provide in addition data on the volumes of each of the cardiac chambers, including the LA, RV, and RA, which can be valuable. ...
... Investigations of the effect of increased heart rate on LV volume during physical exercise as opposed to resting are numerous but are mostly performed on men only. [12][13][14][15][16][17][18][21][22][23] This study, which contains a relatively Adjusted to age and variables, which had p < 0.2 in univariate analysis. Hypertension, diabetes mellitus, hyperlipidemia, overweight, chronic obstructive pulmonary disease, anemia, smoking, and b-blocker were considered as potential confounders for inclusion in multivariate analysis. ...
Article
Background: Currently, normal values of the cardiac chambers' volumes are adjusted only for gender and body surface area (BSA). We aim to investigate the association between the heart rate and the volume of each of the four cardiac chambers using cardiac-gated computed tomography angiography (CCTA). Methods: A total of 350 consecutive patients without known cardiac diseases or significant (>50%) stenosis undergoing CCTA between January 2009 and June 2014 for suspected coronary artery disease were included. Cardiac chamber volumes adjusted to BSA were calculated using automated model-based segmentation analysis software of the CCTA data and correlated with patients' mean heart rate during the scan. Results: There were 240 men and 110 women, median interquartile range age was 55 years (47?61). Women were older 59.0 years (53.7?64) versus 52.0 years (45.0?59.0), had higher prevalence of hyperlipidemia, diabetes mellitus, anemia, and hypothyroidism, and higher median heart rates 64.0 (59.7?66.0) versus 60.0 (55.0?65.0) (p?<?0.001). Men had a negative correlation between the volume of each cardiac chamber and the heart rate [rage_adj?=?(?0.4)?(?0.27), p?<?0.001 for all], whereas such a correlation was not found in women. The multivariate analysis showed that a decrease of five beats per minute was associated with an increase of 4%?5% in volume of each chamber in men. There was no such association among females. Conclusions: Lower heart rate is associated with an increase of each cardiac chamber volume by CCTA in men. This association is not found in women. More extensive studies are required to further elaborate on these gender differences.
... Reliability of LV volumetric and mass measurements between all completed RT short-axis stack constructions was tested using ICC to further evaluate necessary image acquisition time. For reliability during exercise, only LVM was compared to ECG-gated images as volumes, but not mass, were expected to differ between these two physiological conditions 17,33,34 . Similarly, RT CMR images analyzed at end inspiration were not used for volumes as ventricular volumes may differ depending on the respiratory state [17][18][19] . ...
Article
Full-text available
Exercise cardiovascular magnetic resonance (CMR) can unmask cardiac pathology not evident at rest. Real-time CMR in free breathing can be used, but respiratory motion may compromise quantification of left ventricular (LV) function. We aimed to develop and validate a post-processing algorithm that semi-automatically sorts real-time CMR images according to breathing to facilitate quantification of LV function in free breathing exercise. A semi-automatic algorithm utilizing manifold learning (Laplacian Eigenmaps) was developed for respiratory sorting. Feasibility was tested in eight healthy volunteers and eight patients who underwent ECG-gated and real-time CMR at rest. Additionally, volunteers performed exercise CMR at 60% of maximum heart rate. The algorithm was validated for exercise by comparing LV mass during exercise to rest. Respiratory sorting to end expiration and end inspiration (processing time 20 to 40 min) succeeded in all research participants. Bias ± SD for LV mass was 0 ± 5 g when comparing real-time CMR at rest, and 0 ± 7 g when comparing real-time CMR during exercise to ECG-gated at rest. This study presents a semi-automatic algorithm to retrospectively perform respiratory sorting in free breathing real-time CMR. This can facilitate implementation of exercise CMR with non-ECG-gated free breathing real-time imaging, without any additional physiological input.
... Several investigators demonstrated exercise stress CMR using an in-room treadmill system followed by a rapid transfer of the subject into the scanner with subsequent imaging [7][8][9][10][11][12]. On the other hand, MR-compatible equipment enabling imaging at 1.5 tesla (T) while the patient is at peak exercise stress was shown to be feasible for the evaluation of blood flow dynamics and ventricular function in healthy volunteers [13][14][15][16][17][18][19][20]. Another proof-of-concept study reported on a 3T compatible ergometer, which allowed the assessment of cardiac morphology and function in healthy subjects [6]. ...
Article
Background: Cardiac magnetic resonance imaging (CMR) remains underutilized as an exercise imaging modality, mostly because of the limited availability of MR-compatible exercise equipment. This study prospectively evaluates the clinical feasibility of a newly developed MR-conditional pedal ergometer for exercise CMR METHODS: Ten healthy volunteers (mean age 44 ± 16 years) and 11 patients (mean age 60 ± 9 years) with known or suspected coronary artery disease (CAD) underwent rest and post-exercise cinematic 3T CMR. Visual analysis of wall motion abnormalities (WMA) was rated by 2 experienced radiologists, and volumes and ejection fractions (EF) were determined. Image quality was assessed by a 4-point Likert scale for visibility of endocardial borders. Results: Median subjective image quality of real-time Cine at rest was 1 (IQR 1-2) and 2 (IQR 2-2.5) for post-exercise real-time Cine (p = 0.001). Exercise induced a significant increase in heart rate (62 [62-73] to 111 [104-143] bpm, p < 0.0001). Stroke volume and cardiac index increased from resting to post-exercise conditions (85 ± 21 to 101 ± 19 mL and 2.9 ± 0.7 to 6.6 ± 1.9 L/min/m², respectively; both p < 0.0001), driven by a reduction in end-systolic volume (55 ± 20 to 42 ± 21 mL, p < 0.0001). Patients (2/11) with inducible regional WMA at high-resolution post-exercise cine imaging revealed significant coronary artery stenosis in subsequently performed invasive coronary angiography. Conclusion: Exercise-CMR using our newly developed 3T MR-conditional pedal ergometer is clinically feasible. Imaging of both cardiac response and myocardial ischemia, triggered by dynamic stress, is rapidly conducted while the patient is near their peak heart rate.
... Animal studies initially showed that LA relaxation rate, reservoir volume, and mean and V-wave pressures increase during exercise (198). In humans, the LA volume response to exercise remains unclear; several studies using two-dimensional (2D) volumes or diameters have shown increased maximal and stable minimal LA size (199)(200)(201), whereas others demonstrate the opposite (166,202,203), which may reflect differences in study design. However, both perspectives support an expanded reservoir volume proportionate to increases in SV (59) during exercise along with reservoir phase LA strain (172,195). ...
Article
With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures ultimately increasing in association with cardiac output. Recent cardio-pulmonary exercise hemodynamic studies have enriched the available data from healthy adults, yielded insight into the underlying mechanisms which modify the PV pressure-flow relationship, and better delineated the normal limits of healthy responses to exercise. This review will examine hemodynamic function of the RV-PV-LA unit using the 2-element Windkessel model for the pulmonary circulation. It will focus on acute PV and LA responses that accommodate increased RV output during exercise, including PV recruitment and distension and LA reservoir expansion, and the integrated mean pressure-flow response to exercise in healthy adults. Finally, it will consider how these responses may be impacted by age-related remodeling and modified by sex-related cardio-pulmonary differences. Studying the determinants and recognizing the normal limits of PV pressure-flow relations during exercise will improve our understanding of cardio-pulmonary mechanisms that facilitate or limit exercise.
... Inter-scan reproducibility was not assessed with this study, but has been demonstrated in our institution previously in an Ex-CMR study assessing biventricular volumes using a similar retrospectively gated, respiratory navigated short axis cine sequence [42]. As expected, and demonstrated in prior Ex-CMR studies [16,31,46,47], image quality decreases with increasing exercise intensity, however our study still demonstrated good intra-and inter-observer reproducibility during moderate intensity exercise. ECG interference was encountered in one patient, early in the study, such that miss-triggering occurred at moderate exercise intensity. ...
Article
Full-text available
Purpose: Exercise cardiovascular magnetic resonance (Ex-CMR) typically requires complex post-processing or transient exercise cessation, decreasing clinical utility. We aimed to demonstrate the feasibility of assessing biventricular volumes and great vessel flow during continuous in-scanner Ex-CMR, using vendor provided Compressed SENSE (C-SENSE) sequences and commercial analysis software (Cvi42). Methods: 12 healthy volunteers (8-male, age: 35 ± 9 years) underwent continuous supine cycle ergometer (Lode-BV) Ex-CMR (1.5T Philips, Ingenia). Free-breathing, respiratory navigated C-SENSE short-axis cines and aortic/pulmonary phase contrast magnetic resonance (PCMR) sequences were validated against clinical sequences at rest and used during low and moderate intensity Ex-CMR. Optimal PCMR C-SENSE acceleration, C-SENSE-3 (CS3) vs C-SENSE-6 (CS6), was further investigated by image quality scoring. Intra-and inter-operator reproducibility of biventricular and flow indices was performed. Results: All CS3 PCMR image quality scores were superior (p < 0.05) to CS6 sequences, except pulmonary PCMR at moderate exercise. Resting stroke volumes from clinical PCMR sequences correlated stronger with CS3 than CS6 sequences. Resting biventricular volumes from CS3 and clinical sequences correlated very strongly (r > 0.93). During Ex-CMR, biventricular end-diastolic volumes (EDV) remained unchanged, except right-ventricular EDV decreasing at moderate exercise. Biventricular ejection-fractions increased at each stage. Exercise biventricular cine and PCMR stroke volumes correlated very strongly (r ≥ 0.9), demonstrating internal validity. Intra-observer reproducibility was excellent, co-efficient of variance (COV) < 10%. Inter-observer reproducibility was excellent, except for resting right-ventricular, and exercise bi-ventricular end-systolic volumes which were good (COV 10-20%). Conclusion: Biventricular function, aortic and pulmonary flow assessment during continuous Ex-CMR using CS3 sequences is feasible, reproducible and analysable using commercially available software.
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While pharmacologic stress cardiovascular magnetic resonance imaging (MRI) is a robust noninvasive tool in the diagnosis and prognostication of epicardial coronary artery disease, clinical guidelines recommend exercise‐based testing in those patients who can exercise. This review describes the development of exercise cardiovascular MRI protocols, summarizes the insights across various patient populations, and highlights future research initiatives. Level of Evidence 5 Technical Efficacy Stage 2
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While the phases of left atrial (LA) function at rest have been studied, the physiological response of the LA to exercise is undefined. This study defines the exercise behavior of the normal left atrium by quantitating its volumetric response to graded effort. Healthy subjects (n=131) were enrolled from the Health eHeart cohort. Echocardiograms were obtained at baseline and during ramped supine bicycle exercise. Left ventricular volume index, stroke volume index (LVSVI), left atrial end-systolic volume index (LAESVI), end-diastolic volume index (LAEDVI), emptying fraction (LAEF), reservoir and conduit fraction were analyzed. The LVSVI increased with low exercise, but did not increase further with peak exercise; cardiac output increased through the agency of heart rate. The LAESVI and LAEDVI decreased and the LAEF increased with exercise. As a result, LA reservoir volume index was static throughout exercise. The reservoir fraction decreased from 46% at rest to 40% with low exercise (p<0.001) in association with increased LVSVI, and remained similar at peak exercise. The conduit volume index increased from 20 mL/m ² at rest to 24 mL/m ² at low exercise and stayed the same at peak exercise. Similarly, the conduit fraction increased from 54% at rest to 60% at low exercise (p<0.001) and did not change further with peak exercise. Although atrial function increased with exercise, the major contribution to the augmentation of LV SV is LA conduit fraction, a marker of active ventricular relaxation. Furthermore, the major determinant of raising cardiac output during high level exercise is heart rate.
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Background: Patients with pulmonary arterial hypertension (PAH) have a decreased ability to compensate for demands on increased cardiac output, such as during exercise. In this study we aimed to differentiate cardiac exercise responses in patients with PAH, stratified according to known measurements of disease severity. Methods: Right and left ventricular end-diastolic volume and end-systolic volume, stroke volume (SV), and cardiac output were measured in 20 patients with PAH and a lower risk of mortality with 6-month intervals using cardiovascular magnetic resonance (CMR) imaging during rest and during ergometer exercise (totaling 44 scans). Exercise measurements were compared with resting cardiac conditions and clinical assessment using mixed model statistics. Results: SV response during exercise was associated with disease severity. World Health Organization functional class (WHO FC) I and right ventricular end-diastolic volume (RVEDV) <221 ml were associated with increased SV during exercise (WHO FC I: 7% increase in SV; p < 0.001). In contrast, WHO FC II was associated with an 8% decrease in SV (p = 0.02), and SV response declined progressively with right ventricular dilation (7-ml decrease in SV per 100-ml increase in RVEDV; p < 0.001). Conclusions: Assessment of right ventricular function with CMR during exercise stratifies patients currently perceived as having a low risk of mortality into different degrees of right ventricular inotropic reserve. Reduced SV during exercise is a plausible factor to increased risk of decompensation, possibly warranting targeted therapy intensification to restore right ventricular functional reserve.
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Long term endurance training is known to increase peak oxygen uptake (VO2peak) and induce morphological changes of the heart such as increased left ventricular mass (LVM). However, the relationship between and the total heart volume (THV), considering both the left and right ventricular dimensions in both males and females, is not completely described. Therefore, the aim of this study was to test the hypothesis that THV is an independent predictor of VO2peak and to determine if the left and right ventricles enlarge in the same order of magnitude in males and females with a presumed wide range of THV. The study population consisted of 131 subjects of whom 71 were athletes (30 female) and 60 healthy controls (20 female). All subjects underwent cardiovascular MR and maximal incremental exercise test. Total heart volume, LVM and left- and right ventricular end-diastolic volumes (LVEDV, RVEDV) were calculated from short-axis images. was significantly correlated to THV, LVM, LVEDV and RVEDV in both males and females. Multivariable analysis showed that THV was a strong, independent predictor of (R2 = 0.74, p < 0.001). As LVEDV increased, RVEDV increased in the same order of magnitude in both males and females (R2 = 0.87, p < 0.001). Total heart volume is a strong, independent predictor of maximal work capacity for both males and females. Long term endurance training is associated with a physiologically enlarged heart with a balance between the left and right ventricular dimensions in both genders.
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Commercially available software for cardiovascular image analysis often has limited functionality and frequently lacks the careful validation that is required for clinical studies. We have already implemented a cardiovascular image analysis software package and released it as freeware for the research community. However, it was distributed as a stand-alone application and other researchers could not extend it by writing their own custom image analysis algorithms. We believe that the work required to make a clinically applicable prototype can be reduced by making the software extensible, so that researchers can develop their own modules or improvements. Such an initiative might then serve as a bridge between image analysis research and cardiovascular research. The aim of this article is therefore to present the design and validation of a cardiovascular image analysis software package (Segment) and to announce its release in a source code format. Segment can be used for image analysis in magnetic resonance imaging (MRI), computed tomography (CT), single photon emission computed tomography (SPECT) and positron emission tomography (PET). Some of its main features include loading of DICOM images from all major scanner vendors, simultaneous display of multiple image stacks and plane intersections, automated segmentation of the left ventricle, quantification of MRI flow, tools for manual and general object segmentation, quantitative regional wall motion analysis, myocardial viability analysis and image fusion tools. Here we present an overview of the validation results and validation procedures for the functionality of the software. We describe a technique to ensure continued accuracy and validity of the software by implementing and using a test script that tests the functionality of the software and validates the output. The software has been made freely available for research purposes in a source code format on the project home page http://segment.heiberg.se. Segment is a well-validated comprehensive software package for cardiovascular image analysis. It is freely available for research purposes provided that relevant original research publications related to the software are cited.
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We used M-mode echocardiography to measure left ventricular dimensions in diastole (Dd) and systole (Ds) and to assess ventricular performance by computing the percent dimensional shortening (%ΔD) and the normalized rate of dimensional shortening (Vd) during isometric and isotonic exercise in normal subjects. In 27 subjects, isometric handgrip exercise at 50% of maximum grip until fatigue produced a significant increase in Ds (33 ± 3.4 (DS) vs 30.6 ± 3.7 mm, p<0.001), and a reduction in %ΔD (34 ± 4 vs 39 ± 5%, p<0.001) and Vd (1.15 ± 0.15 vs 1.28 ± 0.19 sec-1, p<0.001). Handgrip exercise at 15% of maximum grip produced similar but less marked changes in the 27 subjects, and acute pressure loading with phenylephrine caused similar but more marked changes in 10 of the subjects. In the 20 subjects who performed at least 12 minutes of supine bicycle exercise, Ds decreased significantly (25.6 ± 4.0 vs 31.7 ± 2.8 mm, p<0.001) and %ΔD increased (49 ± 6 vs 36 ± 5%, p<0.001). We observed similar results in the 12 subjects also studied during upright bicycle exercise. Dd was smaller in the upright position but unchanged during either isometric or isotonic exercise. We conclude that: 1) end-diastolic left ventricular size is maintained during isometric exercise and moderate dynamic exercise, even in the upright position; 2) isometric exercise leads to a mild decrease in left ventricular shortening, whereas dynamic exercise results in marked increases in shortening; this difference may be related to the relatively greater increase in blood pressure than in heart rate during isometric exercise; and 3) M-mode echocardiography can be successfully accomplished in selected subjects during various forms of exercise.
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Ten healthy men aged 18 to 23 years performed supine bicycle ergometer exercise during continuous echocardiographic recording. Beat to beat analysis of ventricular dimensions revealed that during constant work load exercise end-diastolic dimension did not change and end-systolic dimension decreased insignificantly by 4 percent. The stroke dimension and fractional shortening of the ventricular dimension rose 7 and 5 percent, respectively. During recovery, end-diastolic dimension and stroke dimension increased above the resting value, beginning 26 seconds (range 16 to 45) after cessation of exercise, whereas heart rate fell promptly to resting levels by 37 seconds. The peak increase in end-diastolic dimension and stroke dimension averaged 11 and 35 percent, respectively. Endsystolic dimension coincident with peak end-diastolic dimension decreased 11 percent in 6 of 10 subjects, and was unchanged in four. Fractional shortening of the ventricular dimension increased 8 percent (P < 0.025) in parallel with end-diastolic dimension.These dimensional changes indicate a significant increase in end-diastolic dimension and stroke dimension in all 10 subjects during the recovery phase of supine exercise with a parallel rise in the percent shortening of the ventricular dimensions. During exercise a clear Frank-Starling effect is masked, whereas during recovery the continuing high level of venous return is dissociated from the decreasing heart rate, resulting in a transient increase in end-diastolic volume and a measurable Frank-Starling effect.
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This investigation examines the hypothesis that athletes increase stroke volume with submaximal exercise through an augmentation of left ventricular (LV) end-diastolic volume and a reduction of LV end-systolic volume, whereas sedentary adults only increase stroke volume modestly, because LV end-diastolic volume does not increase. Upright bicycle exercise was performed by 17 endurance-trained male athletes and 15 sedentary men. M-mode echocardiograms were obtained during submaximal exercise at predetermined heart rates. Athletes, at a heart rate of 130 beats/min, increased their stroke volume 67% from 72 +/- 18 ml to 120 +/- 26 ml (p less than 0.001). This resulted from an increase of LV end-diastolic volume from 119 +/- 23 to 152 +/- 28 ml (p less than 0.001) and a reduction in LV end-systolic volume from 46 +/- 14 to 31 +/- 9 ml (p less than 0.001). Sedentary men at the same heart rate increased stroke volume 22% from 63 +/- 15 to 77 +/- 21 ml (p less than 0.05). LV end-diastolic volume did not change (96 +/- 20 vs 97 +/- 28 ml) (p = not significant), but LV end-systolic volume decreased (33 +/- 11 vs 20 +/- 9 ml) (p less than 0.001). In conclusion, athletes increased cardiac output through a more prominent augmentation of stroke volume than sedentary subjects at submaximal exercise. This was accomplished through an augmentation of LV end-diastolic volume. This may have a conserving effect on myocardial oxygen consumption at these levels of exercise.
Article
Right ventricular (RV) adaptation to supine exercise has been studied in 10 young male volunteers by 81mKr electrocardiogram (ECG)-gated radionuclide ventriculography. During progressive supine exercise, the ejection fraction gradually increased from a mean value of 46% at rest up to 60% at a maximal exercise level. End-diastolic volume however remained unchanged at a low exercise level and even slightly decreased at a higher exercise level. Little or no change in end-diastolic volume and an increase in ejection fraction produced a significant decrease in end-systolic volume and a net increase in stroke volume. These results indicate that the Frank-Starling mechanism does not contribute to the increase in right ventricular stroke volume during progressive supine exercise, but the increase in right ventricular stroke volume rather seems related to an increased contractility, presumably mediated by an increased sympathetic activity.
Article
To assess left ventricular structure and function at rest and during exercise in endurance athletes, 10 elite marathon runners, aged 28 to 37 years, and 10 matched nonathletes were studied by echocardiography and supine bicycle ergometry. Each athlete's best marathon time was less than 2 h 16 min. Echocardiography was performed at rest, at a 60 W work load and at an individually adjusted work load, at which heart rate was 110 beats/min (physical working capacity 110 [PWC110]). Oxygen uptake at PWC110 averaged (+/- SD) 1.14 +/- 0.2 liters/min in the nonathletes and 2.0 +/- 0.2 liters/min in the runners (p less than 0.001). The left ventricular internal diameter at end-diastole was similar at the three activity levels in the control subjects but increased significantly from rest to exercise in the runners (p less than 0.001). Left ventricular systolic meridional wall stress remained unchanged during exercise in the nonathletes but was significantly higher at PWC110 in the athletes (p less than 0.05). Both the systolic peak velocity of posterior wall endocardial displacement and fractional shortening of the left ventricular internal diameter increased with exercise; at PWC110 the endocardial peak velocity was higher in the runners than in the control subjects (p less than 0.01). The endocardial peak velocity during relaxation was comparable in athletes and control subjects at rest, increased similarly at a 60 W work load, but was higher in the runners at PWC110 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)