(Circulation. 1995;92:216-222.)
© 1995 American Heart Association, Inc.
Articles |
Peak Oxygen Consumption and Resting Left Ventricular Ejection Fraction Changes After Cardiomyoplasty at 6-Month Follow-up
From the Heart Institute, São Paulo (Brazil) University Medical School.
Correspondence to Edimar Alcides Bocchi, MD, Rua Oscar Freire, 2077, Apto 161, Cep 05409-011, São Paulo, Brasil. E-mail: dcl_edimar@pinatubo.incor.usp.br.
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Abstract |
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 Top Abstract IntroductionMethods Results Discussion References |
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Background The effects of cardiomyoplasty on cardiopulmonary exercise test characteristics are not fully known.
Methods and Results We determined in 19 patients who
underwent cardiomyoplasty for treatment of refractory heart failure
(New York Heart Association [NYHA] functional class III) before
(pre)
and at 6-month follow-up (post) maximum oxygen consumption (peak
O2), NYHA functional class,
and resting
left ventricular ejection fraction (LVEF) (MUGA). We
analyzed the results according to pre peak
O2 < or >14 mL/kg per
minute and the correlation between the changes in absolute values of
LVEF and peak O2.
Pre– and post–peak
O2 values were
15.9±4.4 and 18.6±6.4
mL/kg per minute, respectively (P=.059). In the subgroup
with pre–peak O2
<14 mL/kg per minute,
the peak O2 increased from
11.1±1.9 to
16.4±6.2 mL/kg per minute (P=.02). The subgroup with
peak
O2 >14 mL/kg per minute
showed pre–
and post–peak O2 of
19.2±2.6 and of
20.1±7 mL/kg per minute, respectively (P=.06). The
pre–total exercise time of the entire group increased from
688.4±222.1 to 833.7±241.6 seconds (P<.04). For the
subgroup with preoperative peak
O2 <14
mL/kg per minute, exercise time improved from 585±76.9 to
825±186.3
seconds (P<.01). In the subgroup with preoperative
O2 >14 mL/kg per minute,
the preexercise and postexercise time was 763.6±264.4 and
840±282
seconds, respectively (P=.4). Pre- LVEF increased from
20.6±3.3% to 24.2±7.8% at 6 months of follow-up
(P=.02). At 6 months of follow-up, 9 patients were in
NYHA functional class I and 10 were in class II. There was no
correlation between LVEF values and absolute values of peak
O2 before
(r=.123,
P=.6) and after (r=.27, P=.2)
cardiomyoplasty. A weak correlation was observed between the changes in
absolute values of peak O2
and LVEF from
the preoperative to the postoperative period (r=.48,
P=.048).
Conclusions Cardiomyoplasty is a useful method for
improving NYHA functional class and LVEF in patients with heart
failure. Peak O2 <14
mL/kg per minute
before cardiomyoplasty may be a selection criterion with which
to determine improved exercise capacity after surgery. The effects of
cardiomyoplasty on LVEF appear to be partially associated with maximum
exercise capacity changes.
Key Words: cardiomyoplasty • heart failure • exercise
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Introduction |
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TopAbstractIntroductionMethods Results Discussion References |
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Dynamic cardiomyoplasty is a surgical procedure directed toward treatment of heart failure.1 In this procedure, a latissimus dorsi muscle flap is wrapped around the ventricles and stimulated in synchrony with cardiac systolic activity.2 3 In selected patients, studies have shown that the procedure improves New York Heart Association (NYHA) functional class,4 5 6 7 left ventricular function,8 regional left ventricular wall motion with changes in geometry,9 and hemodynamic parameters at rest and during exercise.10 In addition, there has been a report of an increase in left ventricular maximal elastance and reduction of systolic wall stress, end-diastolic circumferential stress, and chamber and muscle stiffness associated with changes in left ventricular diastolic filling.11
Also, improvement in maximum oxygen consumption (peak
O2) during exercise has
been
demonstrated.6 10 12 However, these
previous studies did
not describe other treadmill exercise characteristics, and they were
limited by a small number of patients7 or associated
procedures to cardiomyoplasty.12 In addition, these
studies did not provide selection criteria for improvement in
peak O2 after
cardiomyoplasty.
Accordingly, the purpose of the present study was to investigate
the effects of dynamic cardiomyoplasty on cardiopulmonary
treadmill exercise test characteristics and resting left
ventricular ejection fraction (LVEF) at 6-month
follow-up. Also, we studied the correlation between the absolute
values of preoperative peak
O2 and its
improvement after cardiomyoplasty.
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Methods |
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TopAbstractIntroductionMethods Results Discussion References |
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Study Population
In the study period from May 1988 to March 1993, 32 patients underwent cardiomyoplasty at Heart Institute, University of São Paulo (Brazil) Medical School. None of the patients died in the immediate postoperative period, but one patient had to have heart transplantation. Three patients died before 6-month follow-up. Nine patients were excluded owing to the following reasons: sustained ventricular tachycardiac episode during exercise (1), atrial fibrillation with high ventricular rate during exercise (1), technical limitation in interpreting the test (1), nonadherence to protocol (1 [from Venezuela]), limitations in determining peak
O2 because
of
osteomuscular disease, or any reason other than dyspnea or fatigue,
such as obesity (1), anxiety (1), recent respiratory tract infection
(1), and not reaching the anaerobic threshold (2).
Accordingly, the study group consisted of 19 patients. The selection of
patients for cardiomyoplasty was performed with previously described
criteria.13 The diagnosis was idiopathic dilated
cardiomyopathy in 16 patients, Chagas' heart
disease in 1, and ischemic cardiomyopathy
in 2. Fifteen patients were men, and mean age was 47±6 years (range,
33 to 55 years). Before cardiomyoplasty, all patients were in New York
Heart Association (NYHA) functional class III despite maximal medical
therapy with diuretics, digitalis, vasodilators (ECA
inhibitors), and potassium reposition beyond the standard
treatment of heart failure. The doses of diuretics were reduced
or remained the same, and the doses of vasodilators did not change at
6-month follow-up. Patients were asked to provide written special
informed consent in accordance with the standards of the Scientific and
Ethic Committee of the Heart Institute, University of São Paulo
Medical School. Table 1
shows additional characteristics
of patients studied.
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Surgical Procedure and Muscle Stimulation Protocol
Cardiomyoplasty was performed in accordance with the
reinforcement technique described by Chachques et al.14
All operations were performed without cardiopulmonary
bypass. Two intramuscular pacing electrodes (Medtronic SP 5528 BV) were
implanted in the muscle flap. An intramyocardial sensing lead
(Medtronic SP 5548 BV) was implanted in either the left or the right
ventricle. The cardiomyostimulator Medtronic SP 1005 BV was used for
muscle stimulation.
Electrical stimulation of the skeletal muscle graft was initiated 2 weeks after the operation. The progressive muscle-conditioning protocol proposed by Chachques et al3 was followed. After 2 months of follow-up, the stimulation frequency of 30 Hz was achieved, and the muscle flap was paced at 1:1 with a heart rate <100 beats per minute (bpm) and 2:1 with a heart rate >100 bpm. Supramaximal pulse amplitude values (4.5 to 6 V) were used for muscle stimulation. The delay between the sensed ventricular event and the muscle burst was adjusted to obtain exact synchronization between muscle flap contraction and ventricular systole.10
Study Design
Before and at 6-month follow-up after
cardiomyoplasty we
determined the following parameters: NYHA functional class,
resting LVEF (in percent) by radionuclide scintigraphy,
peak O2 normalized for body
weight
during cardiopulmonary treadmill exercise, total exercise
time, heart rate, and maximum pulmonary ventilation. In
addition to standard analysis of patient data, we compared the
results of two subgroups according to peak
O2 before the
cardiomyoplasty: >14 and
<14 mL/kg per minute. The limit was considered to be 14 mL/kg per
minute on the basis of the importance of this value in the indication
for heart transplantation, and this limit is related to an unacceptable
quality of life.15 The subgroups had similar baseline
characteristics before cardiomyoplasty except for peak
O2 (Table
1
).
Furthermore, the correlation between resting LVEF changes and peak
O2 was studied to clarify
the mechanisms
of cardiomyoplasty effects. The changes in parameters were
calculated according to the differences between the postoperative and
preoperative absolute values.
Cardiopulmonary Exercise Test
On the day before the study,
treadmill exercise was performed to
familiarize the patients with the protocol. On the next day, the
subjects underwent 12-lead resting ECG and a progressive treadmill
exercise test, with continuous monitoring of ECG, cuff blood pressure,
ventilation, and gas exchange during the test, including the recovery
period. Subjects were asked to refrain from cigarette smoking and
consumption of caffeinated beverages on the day of the test. All
patients were studied in an air-conditioned (21°C to 23°C)
exercise facility at least 2 hours after a light meal. The exercises
were performed on a programmable treadmill (Quinton Instrument Co)
according to a modified Naughton protocol.16 After 2
minutes of resting recordings while on the treadmill, all
patients were encouraged to exercise until symptoms (fatigue or
dyspnea) made them unable to continue. All patients reached the
anaerobic threshold. Expired fractions of O2
(by zirconium fuel-cell sensor) and CO2 (infrared
absorption) and the rate of air flow were measured by
metabolic analyzer and by the linearized
pneumotachometer at rest (standing) and throughout the exercise period
and recovery with a breathing apparatus consisting of a
mouthpiece, nose clamp, and low-resistance two-way valve (dead
space, 100 mL; Hans-Rudolph). Ventilatory and gas exchange data were
determined on a breath-by-breath basis with a computerized
system (model CAD/Net 2001, Medical Graphics Corporation). The
following measurements were derived on a breath-by-breath
basis: O2 uptake normalized for body weight
(O2, mL/kg per minute),
CO2 production
(CO2, mL/min), end-tidal
oxygen partial pressure (PETO2), end-tidal
carbon pressure (PETCO2), ventilatory
equivalent exchange ratio (RER)
(CO2/O2),
minute pulmonary ventilation (VE, mL/min), the
ventilatory equivalent for oxygen
(VE/O2), and the
ventilatory
equivalent for carbon dioxide
(VE/CO2). Peak
O2 was considered the
highest
O2 achieved in a presumed
maximal effort
exercise test.17 Maximal ventilation was determined by the
average of all breaths within a 30-second period surrounding the
highest recorded O2. To
determine
anaerobic threshold (AT), the following criteria were
used18 : systematic increase in
VE/O2 without
increase in
VE/CO2, systematic
increase in PETO2 without a decrease of
PETCO2, and systematic increase in
RER.
LVEF
Left ventricular radionuclide
scintigraphy was obtained after in vivo labeling of red
blood cells with 99mTc. Gated–blood pool imaging was
acquired in the left anterior oblique view with an Anger Camera 9, Ohio
Nuclear) equipped with an S-500 computer (Sopha Medical Systems, Inc).
Left ventricular volumes and LVEF were calculated by
standard formulas.
Statistical Analysis
Statistical analysis was performed with
Student's
t test for paired or nonpaired testing, as appropriate. A
value of P<.05 was considered statistically significant.
Data are presented as mean±SD. The relations between
variables were examined with linear regression
analysis.
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Results |
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TopAbstractIntroductionMethods Results Discussion References |
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Cardiopulmonary Exercise Test
The mean value of peak
O2 before
the cardiomyoplasty was 15.9±4.4 mL/kg per minute and at 6 months
after the operation was 18.6±6.4 mL/kg per minute
(P=.059)
(Fig 1). The subgroup (11 patients) with
preoperative peak O2 >14
mL/kg per
minute showed peak O2 of
19.2±2.6 mL/kg
per minute before the operation and 20.1±7 mL/kg per minute at 6-month
follow-up (P=.06) (Fig 2).
However, in contrast, the subgroup of patients (8 patients) with
preoperative peak O2 <14
mL/kg per
minute presented a statistically significant improvement in
peak O2. In this subgroup,
the peak
O2 increased from
11.1±1.9 to 16.4±6.2
mL/kg per minute (P=.02) (Fig 3). Fig
4 shows a plot
between preoperative peak
O2 values and
peak O2 improvement. The
values of
VE/O2 of the
entire group
before the operation and at 6-month follow-up were 54±29 and
54±16 (P=NS), respectively; 65±42 and
64±19
(P=NS) in the subgroup with peak
O2 <14 mL/kg per minute
before the
surgery; and 46±9 and 47±10 (P=NS) in the
subgroup with
preoperative peak O2 >14
mL/kg per
minute. The exercise time of the entire group was 688.4±222.1 seconds
before cardiomyoplasty and 833.7±241.6 seconds after
cardiomyoplasty (P<.04). In the subgroup with preoperative
peak O2 <14 mL/kg per
minute, the
exercise time improved from 585±76.9 to 825±186.3 seconds
(P<.01). In the subgroup with preoperative
O2 >14 mL/kg per minute,
the
preexercise and postexercise times were 763.6±264.4 and 840±282
seconds, respectively (P=.4). The maximum heart rate during
exercise for the entire group was 149±26 bpm before cardiomyoplasty
and 153±22 bpm after cardiomyoplasty (P=NS). In the
subgroup with preoperative peak
O2 >14 mL/kg per minute,
the preoperative and postoperative maximum heart rates were 154±30 and
152±21 bpm, respectively (P=NS). For the subgroup with
preoperative peak O2 <14
mL/kg per
minute, the preoperative and postoperative maximum heart rates were
140±30 and 155±25 bpm (P=NS) (Fig
5).
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-peak
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NYHA Functional Class
At 6 months of follow-up 9 patients
were in NYHA functional
class I, and 10 patients were in class II (Table 2). Therefore,
cardiomyoplasty determined
improvement in NYHA functional class in most surviving patients. Eight
patients with peak O2
<14 mL/kg per
minute before cardiomyoplasty had improvement of NYHA functional class
from class III to class II (5 patients) or to class I (3 patients). In
the subgroup with peak O2
>14 mL/kg per
minute before the surgery, NYHA functional class increased from class
III to class I in 6 patients and to class II in 5 patients.
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LVEF
Cardiomyoplasty determined improvement in LVEF from
20.6±3.3%
(before surgery) to 24.2±7.8% at 6-month follow-up
(P=.02). Fig 6 shows the individual variation
of LVEF from before surgery to 6-month follow-up. In the subgroup
with preoperative peak O2
<14 mL/kg per
minute, LVEF improved from 20.4±3.7% to 26.1±11%
(P=.09). In the subgroup with peak
O2 >14 mL/kg per minute
before the
operation, LVEF increased from 21±2.7% to 24±3.2%
(P=.04).
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Correlation Between Changes in LVEF, NYHA Functional Class, and
Peak O2
Table
2 presents an analysis of results on a
patient-by-patient basis. There was no correlation between
resting LVEF values and absolute peak
O2
values before (r=.123, P=.6) and after
(r=.27, P=.2) cardiomyoplasty. Also, there was
no
correlation between NYHA functional class and changes in peak
O2 or LVEF. However, a weak
correlation
was observed for maximum changes in peak
O2 and LVEF between before
cardiomyoplasty and 6-month follow-up (r=.48,
P=.048) (Fig 6).
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Discussion |
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TopAbstractIntroductionMethods Results Discussion References |
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The results of the present study demonstrate that cardiomyoplasty improves LVEF and NYHA functional class in patients with heart failure by 6-month follow-up. There was a trend that did not achieve statistical significance for peak
O2 improvement in the
entire
group. Cardiomyoplasty improved peak
O2
and exercise time in patients with preoperative peak
O2 <14 mL/kg per minute.
In addition,
there was a statistically weak correlation between the changes in left
ventricular ejection fraction and peak
O2 absolute values from
before cardiomyoplasty to 6-month follow-up.
Left ventricular function and functional class results are
consistent with results of the US Food and Drug Administration
(FDA) Phase II American Cardiomyoplasty Study and other studies that
showed improvement in LVEF, left ventricular regional wall
motion, and clinical status after
cardiomyoplasty.3 8 9 12 19 20 21 22
Multiple mechanisms have
been proposed to explain the left ventricular
systolic effects of cardiomyoplasty, such as reduction in left
ventricular stress,11 23 improvement in
ventricular wall motion owing to active reinforcement,
passive reinforcement limiting heart dilatation,3 changes
in left ventricular geometry,9 decreased
myocardial O2, and enhanced
coronary
revascularization.5 24 25 Concerning
NYHA functional class results, despite modest and nonuniform beneficial
effects on left ventricular function and peak
O2, cardiomyoplasty
produced improvement
in NYHA functional class in all patients. This finding is confirmed by
other studies that had difficulty correlating clinical success with
improvement in resting LVEF and resting hemodynamic
data after
cardiomyoplasty.5 22 26 27
The poor correlation
between LVEF at rest and exercise capacity before and after the
cardiomyoplasty are corroborated by studies that demonstrated disparity
between resting measures of left ventricular function and
maximal exercise
capacity.28 29 30 31 Also,
divergence between
improvement in resting LVEF and exercise tolerance with medical
treatment has been reported.32 In the present study,
we found a weak but statistically significant correlation between
changes in LVEF and peak O2
changes. The
reasons for these findings are unclear. One could speculate that
cardiomyoplasty may have additional effects on other determinants of
NYHA functional class or exercise capacity, such as cardiac
diastolic function or cardiovascular
reserve during exercise and even a placebo effect.
The observed tendency of improvement in peak
O2 during cardiopulmonary
treadmill tests is in contrast to the FDA Phase II American
Cardiomyoplasty Study results.22 However, the improvement
is in concordance with previous reports that showed statistically
significant improvement in maximal exercise capacity after
cardiomyoplasty.12 33 However, the preoperative mean
values of peak O2 in these
previous
studies were lower than values in the present study, except in the
FDA American Cardiomyoplasty Phase II Study.22 On the
other hand, postoperative data after cardiomyoplasty in our and other
investigations showed peak
O2 values
between 18 and 19 mL/kg per minute.12 27 Also, after
successful heart transplantation, peak
O2 was close to 19 mL/kg
per
minute.34 It appears that methods to treat heart failure
may have limitations in normalizing peak
O2. Thus, the preoperative
value of peak
O2 should be included among
selection
criteria aimed at successful cardiomyoplasty. This assumption may be
supported by our subgroup results that showed a substantial improvement
in patients with preoperative peak
O2
<14 mL/kg per minute. Mechanisms of cardiomyoplasty effects
determining improvement in peak
O2 are
not unknown. Also, pathophysiological
mechanisms underlying the exercise limitation of patients with chronic
heart failure are not clear. It is postulated that in patients with
heart failure35 multiple abnormalities may affect exercise
capacity, such as central (systolic and diastolic
function, pulmonary hemodynamics, and
neurohumoral mechanisms), peripheral (blood flow
abnormalities, vasodilatory capacity, and skeletal muscle
biochemistry), and ventilatory factors (pulmonary pressure,
physiological dead space, ventilation-perfusion
mismatch, respiratory control, and breathing
pattern).36 37 38 It has been postulated
that maximal heart
rate, maximal cardiac output, and their changes from rest to maximal
exercise appear to account for the greatest variances in exercise
capacity.30 39 Resting effects of cardiomyoplasty on
central factors, including systolic and diastolic
left ventricular functions, have been
demonstrated.3 8 Resting hemodynamic
improvement is not a universal finding. However, evaluations were
usually performed at rest and not during exercise. To our knowledge,
only one investigation was performed during exercise, and the
investigators demonstrated improvement in hemodynamics
during treadmill upright exercise after cardiomyoplasty.10
Thus, theoretically one might speculate that a main effect of
cardiomyoplasty during exercise would be to provide higher left
ventricular stroke volume, probably owing to a beneficial
systolic effect and possibly a diastolic effect of
exercise. This can be supported by our results showing no statistically
significant change in maximal exercise heart rate. It is believed that
diastolic dysfunction may contribute to exercise capacity,
and a beneficial diastolic effect of cardiomyoplasty has
been demonstrated.30 On the other hand, investigators have
suggested that abnormalities in the periphery may contribute to
exercise performance in chronic heart failure.40
Thus, the increments of cardiac output and peripheral blood
flow could lead to an improvement in peripheral components,
including muscles. Regarding other factors, cardiomyoplasty did not
affect pulmonary ventilation in our study, and it did not
change neurohormonal activity and baroreflex sensitivity in patients
with heart failure.41 Further studies should be undertaken
to investigate the effects of cardiomyoplasty on parameters
determinants of exercise.
Study Limitations
This investigation is limited by the small
number of study
patients in a restricted 6-month follow-up period and the lack of a
comparable control group. However, at 6-month follow-up, most
conditioned muscle could be evaluated to determine cardiac effects. On
the other hand, in a longer mean follow-up, late muscle
degenerative changes after cardiomyoplasty were
demonstrated.42 The present study was limited in that
exercise LVEFs were not determined. Parameters of left
ventricular function measured at rest do not necessarily
reflect the most important feature of central
hemodynamics—the ability to increase the
supply of oxygen to the metabolically active tissues, or
the reserve capacity of cardiovascular
system.43 However, methods for determining left
ventricular function reserve are not available for clinical
use, and difficulty in obtaining accurate measures during exercise
should be considered. Also, peak
O2 is
influenced not only by the subject's motivation but also by the
philosophy of the persons supervising the test concerning when the test
should be terminated.44 However, in the present study,
the same team supervised all tests. Our study did not include
cardiopulmonary exercise tests with on and off conditions
for the myostimulator. Differences between these conditions have been
reported concerning resting LVEF and hemodynamic data
after cardiomyoplasty.9 This issue should be addressed in
future studies.
Conclusions and Clinical Implications
Cardiomyoplasty is a
useful surgical method for improving NYHA
functional class and resting LVEF at 6-month follow-up. With regard
to exercise, the cardiomyoplasty may not have a significant impact on
peak exercise performance. However, cardiomyoplasty appears to
be able to improve peak O2
in selected
patients with more restricted exercise capacity and, with the use of
selection criteria that include preoperative peak
O2, may be associated with
better
results concerning peak O2.
Although
peak O2 <14 mL/kg per
minute was found, this by no means represents an inflexible
guideline, and the ultimate decision to perform cardiomyoplasty should
be based on multiple parameters. Effects of cardiomyoplasty
on exercise capacity may be influenced by factors other than the
resting systolic cardiac effects resulting from the procedure.
Further studies should be performed to clarify the effects of
cardiomyoplasty on mechanisms determining exercise capacity in patients
with heart failure.
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References |
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TopAbstractIntroductionMethods Results Discussion References |
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1. Moreira LF, Stolf NAG, Bocchi EA, Pereira-Barreto AC, Meneghetti JC, Giorgi MCP, Moraes AV, Leite JJ, Luz PL, Jatene AD. Latissimus dorsi cardiomyoplasty in the treatment of patients with dilated cardiomyoplasty. Circulation. 1990;82(suppl IV): IV-257-IV-263.
2. Carpentier A, Chachques JC. Myocardial substitution with a stimulated skeletal muscle successful clinical case. Lancet. 1985;1:1267. [Medline] [Order article via Infotrieve]
3. Chachques JC, Grandjean P, Schwartz K, Mihaileanu S, Fardeau M, Swynghedaum B, Fontaliram F, Romero N, Wisnewsky C, Perier P, Chauvaud S, Bourgeois I, Carpentier A. Effect of latissimus dorsi dynamic cardiomyoplasty on ventricular function. Circulation. 1988;78(suppl III):III-203-III-216.
4. Grandjean PA, Austin L, Chan S, Terpstra B, Bourgeois IM. Dynamic cardiomyoplasty: clinical follow-up results. J Cardiac Surg. 1991;6(suppl):80-88.
5. Carpentier A, Chachques JC. Clinical dynamic cardiomyoplasty: method and outcome. Semin Thorac Cardiovasc Surg. 1991;3:136-139. [Medline] [Order article via Infotrieve]
6. Moreira LF, Seferian P, Bocchi EA, Fernandes PMP, Stolf NAG, Barreto ACP, Jatene AD. Survival improvement with dynamic cardiomyoplasty in patients with dilated cardiomyopathy. Circulation. 1991;84(suppl III):III-296-III-302.
7. Bocchi EA, Bellotti G, Moreira LFP, Gutierrez PS, Stolf N, Jatene A, Pileggi F. Prognostic indicators of one-year outcome after cardiomyoplasty for idiopathic dilated cardiomyopathy. Am J Cardiol. 1994;73:604-608. [Medline] [Order article via Infotrieve]
8. Jatene AD, Moreira LF, Bocchi EA, Stolf NAG, Seferian P, Fernandes PMP, Abensur H. Left ventricular function changes after cardiomyoplasty in patients with dilated cardiomyopathy. J Thorac Cardiovasc Surg. 1991;102:132-139. [Abstract]
9. Bocchi EA, Moreira LFP, Moraes AV, Bellotti G, Gama M, Stolf NAG, Jatene AD, Pileggi F. Effects of dynamic cardiomyoplasty on regional wall motion, ejection fraction, and geometry of left ventricle. Circulation. 1992;86(suppl 2):II-231-II-235.
10. Bocchi EA, Moreira LFP, Bellotti G, Barreto ACP, Azul LGS, Stolf NAG, Jatene AD, Pileggi F. Hemodynamic study during upright isotonic exercise before and six months after dynamic cardiomyoplasty for idiopathic dilated cardiomyopathy or Chagas' disease. Am J Cardiol. 1991;67:213-214. [Medline] [Order article via Infotrieve]
11. Bellotti G, Moraes A, Bocchi E, Arie S, Medeiros C, Moreira LF, Jatene A, Pileggi F. Late effects of cardiomyoplasty on left ventricular mechanics and diastolic filling. Circulation. 1993;88(part 2):304-308.
12. Carpentier A, Chachques JC, Acar C, Relland J, Mihaileanu S, Bensasson D, Kieffer J-P, Guibourt P, Tournay D, Rousin I, Grandjean PA. Dynamic cardiomyoplasty at seven years. J Thorac Cardiovasc Surg. 1993;106:42-54. [Abstract]
13. Bocchi EA, Moreira LF, Moraes AV, Bacal F, Sosa E, Stolf NAG, Bellotti G, Jatene AD, Pileggi F. Arrhythmias and sudden death after dynamic cardiomyoplasty. Circulation. 1994;90(suppl 2): II-107-II-111.
14. Chachques LC, Grandjean PA, Carpentier A. Latissimus dorsi dynamic cardiomyoplasty. Ann Thorac Surg. 1989;47:600-604. [Abstract]
15. Mudge GH, Goldstein S, Addonizio LJ, Caplan A, Mancini D, Levine TB, Ritsch ME, Stevenson LW. 24th Bethesda Conference: Cardiac Transplantation, Task Force 3: recipient guidelines/prioritization. J Am Coll Cardiol. 1993;22:21-31. [Medline] [Order article via Infotrieve]
16. Patterson JA, Naughton J, Pietras RJ. Treadmill exercise in assessment of functional capacity of patients with severe left ventricular disease. Am J Cardiol. 1972;30:757-762. [Medline] [Order article via Infotrieve]
17. Wasserman K, Hansem JE, Sue DY. Principles of Exercise Testing and Interpretation. Philadelphia, Pa: Lea & Febiger; 1987:29-36.
18. Wasserman K, Whipp BJ, Koyal SN, Beaver WL. Anaerobic threshold and respiratory gas exchange during exercise. J Appl Physiol. 1973;33:236-243.
19. Almada H, Molteni L, Ferreira R, Ortega D. Clinical experience with dynamic cardiomyoplasty. J Card Surg. 1990;5:193-198. [Medline] [Order article via Infotrieve]
20. Lorusso R, Zogno M, Canna G, Metra M, Sandrelli L, Borghetti V, Maisano F, Alfieri O. Dynamic cardiomyoplasty as an effective therapy for the dilated cardiomyopathy. J Cardiol Surg. 1993;8:177-183.
21. Jegaden O, Delahaye F, Finet G, Van Der Veen F, Montagna P, Eker A, Ossete J, Rossi R, Pierre AS, Mikaeloff PH. Late hemodynamic results after cardiomyoplasty in congestive heart failure. Ann Thorac Surg. 1994;57:1151-1157. [Abstract]
22. Furnary AP, Moreira LFP, Jessup M, and the American Cardiomyoplasty Group. Dynamic cardiomyoplasty improves systolic ventricular function. Circulation. 1994;90:309. Aabstract.
23. Cho RW, Levin HR, Curtis WE, Tsitlik JE, Dinatale JM, Kass DA, Gardner TJ, Kunel RW, Acker MA. Pressure-volume analysis of changes in cardiac function in chronic cardiomyopathy. Ann Thorac Surg. 1993;56:38-45. [Abstract]
24. Nakajima H, Niinami H, Hooper TL, Hammond RL, Nakajima HO, Lu H, Ruggiero R, Thomas GA, Mocek FW, Fietsam R, Krakovsky AA, Spanta AD, Suga H, Stephenson LW, Baciewicz FA. Cardiomyoplasty: probable mechanism of effectivenesss using the pressure-volume relationship. Ann Thorac Surg.. 1994;57:407-415. [Abstract]
25. Lee KF, Dignan RJ, Parmar JM, Dyke CM, Benton G, Yeh T, Abd-Elfattah AS, Wechsler AS. Effects of dynamic cardiomyoplasty on left ventricular performance and myocardial mechanics in dilated cardiomyopathy. J Thorac Cardiovasc Surg. 1991;102:124-131. [Abstract]
26. Hill AB, Chiu RC-J. Dynamic cardiomyoplasty for treatment of heart failure. Clin Cardiol. 1989;12:681-688. [Medline] [Order article via Infotrieve]
27.
Clanc P, Girard C, Vedrine C, Mikaeloff P, Estanove
S. Latissimus dorsi cardiomyoplasty:
perioperative management and postoperative
evolution. Chest. 1993;103:214-220.
28.
Marantz PR, Topin JN, Wassertheil-Smoller S, Steingart
RM, Wexler JP, Budner N, Lense L, Wachspress J. The relationship
between left ventricular systolic function and
congestive diagnosed by clinical criteria.
Circulation. 1988;77:607-612.
29. Franciosa JA. Why patients with heart failure die: hemodynamic and functional determinants of survival. Circulation. 1987;75(suppl IV):IV-20-IV-27.
30. Franciosa JA. Functional capacity of patients with chronic left ventricular failure: relationship of bicycle performance to clinical and hemodynamic characterization. Am J Med. 1979;67:460-466. [Medline] [Order article via Infotrieve]
31. Franciosa JA, Park M, Levine TB. Lack of correlation between exercise capacity and indexes of resting left ventricular performance in heart failure. Am J Cardiol. 1981;47:33-39. [Medline] [Order article via Infotrieve]
32. Cohn JN, Johnson G, Ziesche S, Cobb F, Francis G, Tristani F, Smith R, Dunkman WB, Loeb H, Wong M, Bhat G, Goldaman S, Fletcher RD, Doherty J, Hughes CV, Carson P, Cintron G, Shabetai R, Haakenson C. A comparison of enalapril with hydralazine-isosorbide dinitrate in the treatment of chronic congestive heart failure. N Engl J Med. 1991;325:303-310. [Abstract]
33. Moreira LF, Seferian P, Bocchi EA, Pego-Fernandes PM, Stolf NAG, Pereira-Barreto AC, Jatene AD. Survival improvement with dynamic cardiomyoplasty in patients with dilated cardiomyopathy. Circulation. 1991;84(suppl III):III-296-III-302.
34. Marzo KP, Wilson JR, Mancini DM. Effects of cardiac transplantation on ventilatory response to exercise. Am J Cardiol. 1992;69:547-553. [Medline] [Order article via Infotrieve]
35. Myers J, Froelicher VF. Hemodynamic determinants of exercise capacity in chronic heart failure. Ann Intern Med. 1991;115:377-386.
36. Wasserman K. Measures of functional capacity in patients with heart failure. Circulation. 1990;81(suppl II):II-1-II-4.
37. Clark A, Coats A. Mechanisms of exercise intolerance in cardiac failure: abnormalities of skeletal muscle and pulmonary function. Curr Opin Cardiol. 1994;9:305-314. [Medline] [Order article via Infotrieve]
38. Kirlin PC, Grekin R, Das S, Ballor E, Johnson T, Pitt B. Neurohumoral activation during exercise in congestive heart failure. Am J Cardiol. 1986;81:623-629.
39. Franciosa JA, Leddy CL, Wilen M, Schwartz DE. Relation between hemodynamic and ventilatory responses in determining exercise capacity in severe congestive heart failure. Am J Cardiol. 1984;53:127-134. [Medline] [Order article via Infotrieve]
40.
Drexler H, Banhardt U, Meinertz T, Wollschläger
H, Lehamn M, Just H. Contrasting peripheral
short-term and long-term effects of converting enzyme
inhibition in patients with congestive heart failure: a
double-blind, placebo-controlled trial.
Circulation. 1989;79:491-502.
41. Bocchi EA, Lopes HF, Moraes AV, Bacal F, Moreira LF, Bellotti G, Stolf N, Jatene A, Pileggi F. Neurohormonal activity and baroreflex sensitivity after cardiomyoplasty. Eur Heart J. 1994;15:274. Abstract.
42. Kalil-Filho R, Bocchi E, Weiss RG, Rosemberg L, Bacal F, Moreira LF, Stolf NAG, Magalhães ACC, Bellotti G, Jatene A, Pileggi F. Magnetic resonance imaging evaluation of chronic changes in latissimus dorsi cardiomyoplasty. Circulation. 1994;90(suppl 2): II-102-II-106.
43.
Volterrani M, Clark AL, Ludman PF, Swan JW, Adamopoulos
S, Piepoli M, Coats AJS. Predictors of exercise capacity in
chronic heart failure. Eur Heart J. 1994;15:801-809.
44. Itoh H, Taniguchi K, Koike A, Doi M. Evaluation of severity of heart failure using ventilatory gas analysis. Circulation. 1990;81(suppl II):II-31-II-37.
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