|
| |
Electrical
Stimulation For Cardiac Assistance
Adobe Reader Version
Acker M.A., Hammond R., Mannion
J.D., Salmons S., Stephenson L.W. (1986) An autologous biologic pump motor. J
Thorac Cardiovasc Surg 12, 733-746.
Acker M.A., Hammond R.L.,
Mannion J.D., Salmons S., Stephenson L.W. (1987) Skeletal muscle as the
potential power source for a cardiovascular pump: assessment in vivo. Science
236, 324-327.
Aguinaga L., Mont L., Anguera
I., Valentino M., Matas M., and Brugada J. (1998) [Patients with structural
heart disease, syncope of unknown etiology and inducible ventricular arrhythmias
treated with implantable defibrillators]. Rev. Esp. Cardiol. 51, 566-571.
Abstract: OBJECTIVES: This study evaluates the hypothesis that in patients with
syncope of unknown origin and heart anomalies, inducible ventricular arrhythmias
are specific arrhythmias and therefore should be treated as such. BACKGROUND:
Although syncope is a frequent clinical entity, the evaluation and treatment of
patients with syncope without a clear etiology still remains undefined. Many
patients with syncope of undetermined origin undergo invasive electrophysiologic
evaluation. Abnormalities of the sinus node, prolongation of conduction times or
inducible arrhythmias found during these evaluations are usually assumed to be
the cause of syncope, and are consequently treated. However, whether
tachyarrhythmias are truly the cause of syncope, and whether treatment of these
tachyarrhythmias can prevent recurrent syncope and arrhythmic death, is unknown.
PATIENTS AND METHODS: An electrophysiological study was performed on 160
patients with structural heart disease and syncope of unknown origin. In 23 out
of the 160 patients (16%), programmed electrical stimulation induced sustained
ventricular arrhythmias. In 18 out of the 23 patients an automatic defibrillator
was implanted and they form the study group. RESULTS: In these 18 patients,
programmed ventricular stimulation induced sustained monomorphic ventricular
tachycardia in 12, sustained polymorphic ventricular tachycardia in 2 and
ventricular fibrillation in 4. During a mean follow-up of 14 months, 9 patients
received 81 appropriate therapies from the device (53 because of ventricular
tachycardia and 23 because of ventricular fibrillation). The probability of
appropriate therapy was 100% at 1 year follow-up. There were no episodes of
sudden death and 1 patient died of congestive heart failure. CONCLUSIONS: In
patients with syncope of undetermined origin, heart disease and inducible
ventricular tachyarrhythmias treated with a implantable cardioverter
defibrillator, there is a high incidence of appropriate therapies. Our results
support the practice of using implantable cardioverter defibrillators in
patients with syncope of unknown origin, heart disease and inducible ventricular
arrhythmias
Anderson W.A., Ianuzzo C.D.,
and Klabunde R.E. (1996) Cardiomyoplasty: studies on goat latissimus dorsi blood
flow and muscle damage following surgical dissection and chronic electrical
stimulation. J. Card Surg. 11, 237-246.
Abstract: BACKGROUND: Dynamic cardiomyoplasty has shown promise as a surgical
treatment for congestive heart failure, however, skeletal muscle damage has been
reported in the latissimus dorsi muscle flap. Possible etiologies for the muscle
damage include surgical dissection of the latissimus dorsi muscle with
interruption of collateral blood supply, as well as chronic electrical
stimulation of the muscle. METHODS: To investigate these possible etiologies, we
conducted a series of experiments using the goat model, evaluating blood flow
and muscle morphology following surgical dissection and chronic stimulation of
the latissimus dorsi muscle. Four different conditions were evaluated: (1)
latissimus dorsi muscle that was neither dissected nor chronically stimulated;
(2) latissimus dorsi muscle that was stimulated, but not dissected; (3)
latissimus dorsi muscle that was surgically dissected, but not chronically
stimulated; and (4) latissimus dorsi muscle that was both surgically dissected
and chronically stimulated. CONCLUSION: We concluded that skeletal muscle damage
resulted primarily from the surgical dissection, whereby the collateral blood
supply to the latissimus dorsi muscle was interrupted and not primarily as a
result of chronic electrical stimulation
Barron D.J., Etherington P.J.,
Winlove C.P., Jarvis J.C., Salmons S., Pepper J.R. (2001) Combination of
preconditioning and delayed flap elevation: evidence for improved perfusion and
oxygenation of the latissimus dorsi muscle for cardiomyoplasty. Ann Thorac
Surg 71, 852-861.
Bolotin G., van der Veen F.H.,
Lorusso R., Schreuder J.J., Wolf T., David J.B., et al (1998) Aortomyoplasty.
Basic Appl Myol 8, 59-65.
Cabrera Fischer E.I., Christen
A.I., de Forteza E., and Risk M.R. (1999) Dynamic abdominal and thoracic
aortomyoplasty in heart failure: assessment of counterpulsation. Ann. Thorac.
Surg. 67, 1022-1029.
Abstract: BACKGROUND: Aortic counterpulsation, either biologic or mechanical, is
a useful technique to support circulation during left ventricular dysfunction.
METHODS: In this study we used an induced cardiac failure model in acute open
chest sheep to compare hemodynamic improvements between thoracic and abdominal
aortic counterpulsation. This was achieved with left latissimus dorsi and left
hemidiaphragm muscle flaps. RESULTS: Thoracic and abdominal aortic
counterpulsation in heart failure resulted in a significant improvement of
hemodynamic parameters. Subendocardial viability index, defined as diastolic
pressure-time index to systolic tension-time index, in thoracic and abdominal
aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance
was performed by electrical stimulation of each muscle flap. A new
counterpulsation index derived from diastolic and systolic areas beneath the
aortic pressure curve was tested, obtaining a correlation coefficient with the
subendocardial viability index of 0.758 (p<0.001). Values of subendocardial
viability index and counterpulsation index showed minimal variability.
CONCLUSIONS: Treatment of experimentally induced cardiac failure with dynamic
abdominal aortic counterpulsation allows an effective hemodynamic improvement in
open chest sheep. Furthermore, this diastolic arterial pressure augmentation
could be evaluated through a new counterpulsation index derived from diastolic
and systolic areas beneath the aortic pressure curve
Carpentier A., Chachques J-C.
(1985) Myocardial stustitution with a stimulated skeletal muscle: first
successful clinical case. Lancet I, 1267.
Checkanov V.S., Krakovsky A.A.,
Bushlenko N.S., Riabinina L.G., Andreev D.B., Shatalov K.V (1994)
Cardiomyoplasty. Review of early and late results. Vasc Surg 28, 481-488.
Chekanov V.S., Tchekanov G.V.,
Rieder M.A., Silverstein E.L., Cheng Q., Smith L.M., Zander G.L., Jacobs G.B.,
McConchie S., Christensen C.W. (1995) Force enhancement of skeletal muscle used
for dynamic cardiomyoplasty and as a skeletal muscle ventricle. ASAIO J. 41,
M499-M507.
Abstract: Some patients with pre end-stage congestive heart disease do not
receive a significant hemodynamic benefit from dynamic cardiomyoplasty because,
during prolonged preoperative immobilization, their latissimus dorsi muscle (LDM)
becomes extremely weak. It is the authors' hypothesis that the local
administration of an anabolic steroid into an electrically stimulated LDM will
produce a thicker and stronger muscle with significant resistance to fatigue.
The electrical stimulation training protocol of sheep continued for 8 weeks. For
localized anabolic steroid administration an osmotic pump was placed in a
subcutaneous pocket and the catheter was introduced into the LDM. The
contractile force of electrically stimulated and unstimulated control muscle was
studied. Control data were calculated as 100% and all other data were corrected
to control. After 4 weeks there was no decrease in contractile force. The change
seen was from 88 to 100% with different preloads (10, 15, and 20 g/kg) and
amplitudes of impulses (5 and 10 V). After 8 weeks, the LDM was more powerful
than before electrical stimulation, with a change of 97-133%. Usually after 8
weeks of electrical stimulation alone, contractile force decreases to 70-75%.
During a fatigue test (30 min, 100 bursts per minute, 10-25 Hz, ripple
frequency, 10 V impulse amplitude) after 4 and 8 weeks of our protocol, the LDM
lost only 12% of its initial force, whereas control muscle lost 40%. Thus local
anabolic steroid administration makes the LDM stronger and more useful for
cardiomyoplasty
Chekanov V.S., Tchekanov G.V.,
Rieder M.A., Cheng Q., Smith L.M., Zander G.L., Christensen C.W., McConchie S.,
Jacobs G., and Schmidt D.H. (1996) Skeletal muscle of a growing organism has a
greater transformation after electrical stimulation than adult skeletal muscle.
ASAIO J. 42, M630-M636.
Abstract: Six adult sheep and four newborn lambs (5 days old) were implanted
with stimulator leads into the latissimus dorsi muscle and connected to a
Myostim 7220 pacing system (Telectronics Pacing Systems, Inc., Englewood, CO).
Electrical stimulation was started immediately after the operation. After 8
weeks of electrical stimulation, contractile force (CF) in adult sheep decreased
to 76-81%, and to 78-82% in lambs. After 2 weeks' delay, CF in adults was
96-98%, and only 89-93% in lambs. After a 30 min intensive stress test,
unconditioned control muscle lost 39% in lambs and 43% in adults. Muscle
conditioned for 8 weeks lost 7-8% CF. However, after 2 weeks' delay, CF in adult
muscle lost 33%, but only 12% in lambs. After cessation of electrical
stimulation, the LDH-5 and LDH-1 + 2 fractions reverted to initial levels in
adults, whereas in lambs, these levels continued to follow trends established
during electrical stimulation. In both adults and lambs, the percent area
occupied by the mitochondria increased during electrical stimulation by 6.9% in
adults and 6.5% in lambs. After electrical stimulation cessation, the percent
area in adults returned to baseline levels, whereas it continued to be elevated
in lambs (3.3% vs 5.1%, respectively). The transformed muscle of the lamb did
not revert to baseline levels after a delay period
Chekanov V.S. (1999) Change in
electrical stimulation regimen after cardiomyoplasty. Eur. Heart J. 20, 393.
Chekanov V.S., Tchekanov G.V.,
Rieder M.A., Hare J., and Mortada M. (2000) Effects of electrical stimulation
postcardiomyoplasty in a model of chronic heart failure: hemodynamic results
after daily 12-hour cessation versus a nonstop regimen. Pacing Clin.
Electrophysiol. 23, 1094-1102.
Abstract: The hemodynamic effects of cardiomyoplasty (CMP) have been
investigated in many centers, but the question of whether it is necessary to
stimulate the latissimus dorsi muscle (LDM) 24 hours a day has not been
answered. The main goal of our investigation was to determine whether
hemodynamic results after CMP were impaired when continuous electrical
stimulation (ES) was off for 12 hours a day. A model of chronic heart failure
was created in 12 sheep by performing an arteriovenous anastamosis and
administering doxorubicin. Two weeks after the anastomosis, CMP was performed in
eight sheep (experimental series); ES training was begun at 2 weeks after CMP.
After completion of the initial ES conditioning (8 weeks after CMP), one group
of sheep continued to receive ES 24 hours daily. Another group of sheep had only
12 hours of ES daily. Hemodynamic parameters were investigated 2 weeks later
with the stimulator turned on and then off. With doxorubicin administration,
arteriovenous anastamosis created a stable model of biventricular heart failure
(right atrial pressure 20 +/- 3 mmHg vs 6 +/- 2 mmHg at baseline; pulmonary
capillary wedge pressure 18 +/- 3 mmHg vs 9 +/- 2 mmHg; left ventricular
end-diastolic area 15.2 +/- 1.2 cm2 vs 6.4 +/- 0.7 cm2; left ventricular
ejection fraction 0.38 +/- 0.6 vs 0.65 +/- 0.7). Cardiomyoplasty improved
hemodynamic status in all eight experimental sheep. However, when the
investigation was performed with the stimulator off, this improvement was
statistically insignificant. With stimulation on, there was decreased right
atrial pressure, pulmonary capillary wedge pressure, left ventricular end-
diastolic volume, and increased left ventricular ejection fraction. With the
stimulator turned off for 12 hours daily, hemodynamic measurements did not
differ from data with continuous ES for 24 hours daily. Because hemodynamic
results do not seem to be impaired, we recommend daily, periodic cessation of
stimulation to prevent damage to the LDM after CMP
Chen F.Y., Lautz D.B., deGuzman
B.J., Aklog L., Ahmad R.M., Laurence R.G., Couper G.S., Cohn L.H., and McMahon
T.A. (1998) An engineering model of dynamic cardiomyoplasty. I. Ann. Biomed. Eng
26, 441-453.
Abstract: Dynamic cardiomyoplasty (DCM) is an emerging surgical procedure for
heart failure in which the patient's latissimus dorsi (LD) muscle is wrapped
around the heart and stimulated to contract in synchrony with the heartbeat as a
cardiac assist measure. A 6 week training protocol of progressive electrical
stimulation renders the normally fatigueable skeletal muscle fatigue-resistant
and suitable for chronic stimulation. To date, over 500 procedures have been
performed in worldwide clinical trials. Investigators typically report
symptomatic improvement and modest hemodynamic improvement in patients.
Controversy exists regarding the exact mechanism of DCM. To test the hypothesis
that DCM augments cardiac stroke volume through improvement in systolic
function, we formulated an engineering model of dynamic cardiomyoplasty to
predict stroke volume. The heart and the LD were modeled as nested (series)
elastance chambers, and the vasculature was represented by a two-element
Windkessel model. Using five healthy goats, we verified model predictions of
stroke volume for both stimulator ON beats (y = 1.00x-0.08, r = 0.87, p <
0.0001) and OFF beats (y = 1.01x+1.06, r = 0.91, p < 0.0001), where x and y are
the measured and predicted stroke volumes, respectively. The model confirms that
using untrained latissimus dorsi applied to the normal myocardium produces only
moderate increases in stroke volume and suggests that future research should
focus on increasing LD strength after training
Cmolik B.L., Thompson D.R.,
Sherwood J.T., Geha A.S., and George D.T. (2001) Increased coronary artery blood
flow with aortomyoplasty in chronic heart failure. Ann. Thorac. Surg. 71,
284-289.
Abstract: BACKGROUND: We hypothesized that diastolic counter-pulsation using
aortomyoplasty will increase coronary blood flow. METHODS: In dogs (n = 6, 20 to
25 kg), the left latissimus dorsi muscle was isolated, wrapped around the
descending thoracic aorta, and conditioned by chronic electrical stimulation.
Heart failure was induced by rapid ventricular pacing. In a terminal study, left
ventricular and aortic pressures, and blood flow in the left anterior descending
coronary artery and descending aorta were measured. The endocardial-viability
ratio was calculated. RESULTS: Aortomyoplasty increased mean diastolic aortic
pressure (70 +/- 5 to 75 +/- 5 mm Hg, p < 0.05) and reduced peak left
ventricular pressure (86 +/- 4 to 84 +/- 4 mm Hg, p _ 0.05), leading to a 16%
increase in endocardial-viability ratio (1.29 +/- 0.05 to 1.49 +/- 0.05, p <
0.05). Coronary blood flow was increased by 15% (8.2 +/- 1.5 to 9.4 +/- 1.6 mL/min,
p < 0.05). During muscle contraction, 2.7 +/- 0.5 mL was ejected from the
wrapped aortic segment. CONCLUSIONS: These data demonstrate that aortomyoplasty
provides successful diastolic counterpulsation after muscle conditioning and
heart failure
Furnary A.P., Chachques J.C.,
Moreira L.F.P., Grunkemeier G.L., Swanson J.S., Stolf N., et al (1996) Long-term
outcome, survival analysis and risk stratification of dynamic cardiomyoplasty.
J Thorac Cardiovasc Surg 112, 1640-1649.
Gealow K. (1998) Latissimus
dorsi stimulation in dynamic cardiomyoplasty: how should we proceed? Basic
Appl Myol 8, 41-50.
George D.T., DiLoreto G.V.,
Cheng W., Corin W.J., and Santamore W.P. (1992) Voltage-dependent performance of
skeletal muscle pouches: implications for cardiomyoplasty. J. Heart Lung
Transplant. 11, S320-S327.
Abstract: Cardiomyoplasty, a new therapy for heart failure, uses autologous
skeletal muscle to mechanically assist the heart. The success of dynamic
cardiomyoplasty is critically dependent on the contraction strength of the
assisting skeletal muscle. Unlike cardiac muscle, skeletal muscle contracts in a
graded response to electrical stimulation. However, in current cardiomyoplasty
practice, no systematic technique exists to set the stimulating voltage
effecting skeletal muscle contraction. The stimulating voltage is simply set to
some multiple of the "threshold" voltage. Furthermore, researchers do not
consider the role of stimulating voltage when they determine the amount of
assistance afforded during cardiomyoplasty. To more accurately assess the value
of this heuristic voltage-setting technique, we investigated the role of
stimulating voltage on the strength of contraction of the latissimus dorsi
muscle. Six New Zealand white rabbits had isovolumic hydraulic pouches
constructed from the latissimus dorsi muscle. The muscles were wrapped around a
compliant balloon in which isovolumic pressure development was measured during
tetany-inducing burst (pulse-train) stimulation. The tetanic plateau of the
pouch pressure record was used to measure the effects of stimulating voltage on
skeletal muscle contraction. Results indicated that (1) increasing stimulating
voltage from two to four times the "threshold" voltage increased normalized
pouch pressure from 0.38 +/- 0.21 to 0.78 +/- 0.12 (mean +/- SD) (p < 0.05); (2)
the threshold- normalized voltage necessary to cause maximal muscle contraction
varied widely (5.7 +/- 2.0, mean +/- SD; range, 3.1 to 9.3); and (3) the current
achieving maximal pressure development varied from 5.6 to 31.4 mA (19.9 +/- 10.4
mA).(ABSTRACT TRUNCATED AT 250 WORDS)
Girsch W., Koller R., Lanmuller
H., Rab M., Avanessian R., Schima H., Wolner E., and Seitelberger R. (1998)
Experimental development of an electrically stimulated biological skeletal
muscle ventricle for chronic aortic counterpulsation. Eur. J. Cardiothorac. Surg.
13, 78-83.
Abstract: OBJECTIVE: The chronic shortage of donor organs for cardiac
transplantation and the high costs for mechanical assist devices demand the
development of alternative cardiac assist devices for the treatment of severe
heart failure. Cardiac assistance by stimulated skeletal muscles is currently
investigated as such a possible alternative. The goal of the presented study was
to construct a newly designed biological skeletal muscle ventricle and to
evaluate its possible hemodynamic efficacy in an acute sheep model. METHODS: A
total of 14 adult sheep were used for acute experiments. The entire thoracic
aorta including the aortic root was excised from a donor sheep. An aorto-
pericardial pouch conduit (APPC) was created by enlarging the aortic
circumference in its middle section with two strips of pericardium. This
biological conduit was anastomosed in parallel to the descending aorta of a
recipient sheep, using the aortic root as an inflow valve to the conduit.
Stimulation electrodes were applicated to the thoracodorsal nerve and the
latissimus dorsi muscle was detached from the trunk and wrapped around the
pouch. ECG-triggered functional electrical stimulation was applied during
cardiac diastole to simulate aortic counterpulsation. Stimulation was performed
during various hemodynamic conditions. RESULTS: A standardised surgical
procedure suitable for long term studies was established during six experiments.
An APPC, with 70-80 mm filling volume, was found to be of optimal size. In
another eight experiments, hemodynamic measurements were performed. Under stable
hemodynamic conditions the stimulation of the biological skeletal muscle
ventricle induced a significant increase of mean arterial pressure by 14% and
mean diastolic pressure by 26%. During pharmacologically induced periods of
cardiac failure, the stimulation of the APPC increased mean arterial pressure by
13% and mean diastolic pressure by 19%. In all eight experiments, the diastolic
peak pressure reached supra-systolic values during stimulation. CONCLUSIONS: The
results demonstrate the hemodynamic efficacy of this newly designed biological
skeletal muscle ventricle as an aortic counterpulsation device. Chronic
experiments using a preconditioned fatigue-resistant muscle will further help to
evaluate its possible clinical significance
Grandjean P., Acker M., Madoff
R., Williams N.S., Woloszko J., and Kantor C. (1996) Dynamic myoplasty: surgical
transfer and stimulation of skeletal muscle for functional substitution or
enhancement. J. Rehabil. Res. Dev. 33, 133-144.
Abstract: Dynamic myoplasty combines muscle transfer with electrical stimulation
to provide contractile function that augments or replaces impaired organ
function. Dynamic cardiomyoplasty was the first clinical application in which a
skeletal muscle, latissimus dorsi, was transferred and stimulated to provide
cardiac assistance, a function different from its original one. The problem of
early muscle fatigue that was encountered in the initial implementation of the
method was solved by training the muscle with electrical stimulation and thus
changing its fiber composition. With intramuscular electrodes, the conditioned
latissimus dorsi is stimulated in synchrony with the heart muscle. Safeguards
are built into the two-channel implanted stimulator to avoid excessively high
pulse rates. Clinicians report that 80% of patients with moderate to severe
heart failure prior to operation showed a clinical improvement of 1.6 New York
Heart Association classes. Alternative methods of providing cardiac assistance
that are also being investigated include wrapping the muscle around the aorta,
creating a skeletal muscle ventricle, and using the muscle to power an
implantable pump. These latter techniques are still under preclinical
investigation. Compared with heart transplant, cardiomyoplasty has the great
advantage of not being subject to tissue rejection. The second principal
application of dynamic myoplasty is treatment of fecal incontinence through
creation of an electrically stimulated skeletal muscle neosphincter (ESMNS). The
gracilis muscle of the leg is mobilized, wrapped around the anal canal, and
conditioned with electrical stimulation to become more fatigue resistant. To
achieve continence, the muscle is continuously stimulated except when the
patient wishes to defecate. Overall success rates in achieving continence are
60-65%. Both cardiomyoplasty and the ESMNS technique, and their associated
devices, are being refined through ongoing clinical trials
Guldner N.W., Eichstaedt H.C.,
Klapproth P., Tilmans M.H.I., Thuaudet S., Umbrain V., et al (1994) Dynamic
training of skeletal muscle ventricles. A method to increase muscular power for
cardiac assistance. Circulation 89, 1032-1040.
Hagege A.A., Desnos M.,
Chachques J.C., Carpentier A., Fernandez F., Fontaliran F., et al (1990)
Preliminary report: follow-up after dynamic cardiomyoplasty. Lancet
1112-1124.
Hakami A., Santamore W.P.,
Stremel R.W., Tobin G., and Hjortdal V.E. (1999) Evaluation of stimulation
parameters on aortomyoplasty, using Latissimus Dorsi muscle in a goat model: an
acute study. Eur. J. Cardiothorac. Surg. 16, 228-232.
Abstract: OBJECTIVE: Dynamic aortomyoplasty using Latissimus Dorsi muscle (LDM)
has been shown to improve myocardial function. However, systematic examination
of the effects of stimulation parameters on aortic wrap function has not been
done. Thus, the present study measures the direct effect of stimulation voltage,
pulse train duration, frequency of the pulses, and the duration of the
stimulation delay from R wave on the aortic wrap function. METHODS: In eight
female goats, the left LDM was wrapped around the descending aorta. The muscle
was then subjected to electrical stimulation, altering frequency of stimulation
pulses (16.6, 20, 25, 33 and 50 Hz), amplitude (2, 4, 6, 8 and 10 V), and number
of pulses (2, 4, 6, 8 and 10 pulses) in a train stimulation. Left ventricular,
aortic pressure, and pressure generated by LDM on aorta (wrap pressure) was
measured. The changes in hemodynamic parameters mentioned above were calculated
and compared for different stimulation parameters during unassisted and assisted
cardiac cycles. RESULTS: Aortomyoplasty counterpulsation using LDM provided
significant improvement in wrap pressure (78 mmHg +/- 2), aortic diastolic
pressure, and changes in aortic diastolic pressure from 2 to 4 V (P < 0.05).
Further increase in amplitude did not make any significant improvements of the
above mentioned parameters. Significant augmentation of wrap pressure (82 mmHg
+/- 2), aortic diastolic pressure (79 mmHg +/- 3) and changes in aortic
diastolic pressure (12 mmHg +/- 1) occurred at 6 pulses (P < 0.05). Other
changes in number of pulses did not show any significant improvements.
Significant improvement of wrap pressure (80 mmHg +/- 2), aortic diastolic
pressure (73 mmHg +/- 3) and changes in aortic diastolic pressure (12 mmHg +/-
1) was observed with a frequency of 33 Hz. To examine a wide range of delays
from the onset of the QRS complex to LDM stimulation, stimulation was delivered
randomly. The exact delay was determined from the ECG signal and superimposed
LDM stimulation pulses. CONCLUSIONS: In this study we present a new measurement,
wrap pressure. We also present that in aortomyoplasty using LDM, the most
significant improvement in wrap pressure, aortic diastolic pressure and changes
in aortic diastolic pressure occurs when the stimulation consists of an
amplitude of 4 V, a frequency of 33 Hz and a train stimulation of 6 pulses
Harridge S.D., Magnusson G.,
and Gordon A. (1996) Skeletal muscle contractile characteristics and fatigue
resistance in patients with chronic heart failure. Eur. Heart J. 17, 896-901.
Abstract: Whole muscle contractile characteristics and fatigue resistance were
studied in male patients with chronic heart failure (n = 6) and in healthy
control subjects (n = 6). Maximum voluntary isometric strength in the major
muscle groups of leg (plantar flexors and knee extensors) and arm (elbow
extensors and elbow flexors), was found to be similar for both groups of
subjects. However, a faster isometric twitch time course was observed in the
plantar flexor and knee extensor muscles of heart failure chronic patients. The
poor resistance to fatigue in the knee extensors of chronic heart failure
patients was confirmed in the present study, but using twitch interpolation this
was shown not to be due to poor activation. The plantar flexors of chronic heart
failure patients also showed a tendency to be less resistant to fatigue, even
when the muscle was activated by direct electrical stimulation. The present
study shows that independent of muscle strength, patients with chronic heart
failure may possess muscles that are faster to contract and less resistant to
fatigue. However, it seems this increased fatigability is not due to poor muscle
activation
Herreros J., Alegria E., Gil
O., Fernandez Gonzalez A.L., Iglesias I., Barba J., Zabala M.S., Garcia M.J.,
and Arbizu J. (1994) [Dynamic cardiomyoplasty. Preliminary experience]. Rev.
Esp. Cardiol. 47, 23-32.
Abstract: INTRODUCTION AND OBJECTIVES. The purpose of this study is to show our
experience in clinical dynamic cardiomyoplasty. PATIENTS, MATERIALS AND METHODS.
Six patients with end-stage heart failure and 2 patients with left ventricular
aneurysm underwent dynamic cardiomyoplasty using the latissimus dorsi muscle.
The latissimus dorsi was electrically conditioned before the procedure through a
lead placed under local anesthesia and connected to an external cardiac
pace-maker. Surgical technique--including dissection of the latissimus dorsi and
encircling of the ventricles with the muscle flap--was performed in general
terms as described at the Broussais Hospital. In the first 3 patients a bipolar
lead connected to a single impulse generator was used. In the other 5 patients a
train of impulses cardiomyostimulator was used. Changes in systolic function
were studied through Doppler- echocardiography and radionuclide studies. Changes
in diastolic function were evaluated through E wave velocity and deceleration
time. RESULTS. Mean follow up was 9 +/- 5.7 months. No early deaths were
recorded. One patient underwent emergency surgery, one week after the procedure,
because of a tear of the patch used to close the wall defect after left
ventricular aneurysm resection. In 2 patients a subcutaneous serous collection
secondary to muscle dissection was evacuated. One patient died due to a stroke 4
months after the procedure. Another patient died after an unsuccessful coronary
transluminal percutaneous angioplasty 11 months after the procedure. An improved
functional class was observed in all patients. No changes in systolic function
were observed after surgery when the cardiomyoestimulator was turned-off either
with echocardiography (26.7 +/- 8.6 vs 24.8 +/- 5.8% [NS]) or radionuclides
(24.5 +/- 9.5 vs 20.2 +/- 8.3% [NS]). When the cardiomyostimulator was turned-on
a statistically significant increase of the left ventricular ejection fraction
was observed either with echocardiography (24.8 +/- 5.8 vs 37 +/- 10.3%; p <
0.05) or radionuclides (20.2 +/- 8.3 vs 33.3 +/- 12.2%; p < 0.05). This
significant increase of the ejection fraction has been observed in subsequent
studies. Nevertheless the differences when the cardiomyostimulator is turned-on
and turned-off have decreased several months after the procedure. A significant
increase of the left ventricular outflow velocity (cm/seg) was observed when the
generator was turned-on (57.7 +/- 20.4 vs 75.1 +/- 17.8%; p < 0.01). A
significant increase of the dP/dt (mmHg/seg) was observed when the generator was
turned-on (706.3 +/- 291.5 vs 592.6 +/- 181.6%; [NS]). No significant changes
were observed on E wave velocity. A significant decrease of the deceleration
time was observed several months after the procedure (p < 0.05). CONCLUSIONS. We
believe that dynamic cardiomyoplasty is a safe and valid surgical procedure for
some patients with end stage cardiomyopathies as well as in association with
Jatene's technique for the management of left ventricular aneurysms. An
improvement in functional class is present and a significant increase of the
left ventricular systolic function. Nevertheless it is necessary to find new
systolic parameters, independent of volumetric calculations, to evaluate the
mechanical support of the muscle as well as to determine the long-term pattern
of electrical stimulation
Hooper T.L., Salmons S. (1993)
Skeletal muscle assistance in heart failure. Cardiovasc Res 27,
1404-1406.
Kass D.A., Baughman K.L., Pak
P.H., Cho P.W., Levin H.R., Gardner T.J., et al (1995) Reverse remodeling from
cardiomyoplasty in human heart failure. External constraint versus active
assist. Circulation 91, 2314-2318.
Lucas C.M., Van der Veen F.H.,
Cheriex E.C., van O., V, Penn O.C., and Wellens H.J. (1992) The importance of
muscle relaxation in dynamic cardiomyoplasty. Pacing Clin. Electrophysiol. 15,
1430-1436.
Abstract: During the last decade dynamic cardiomyoplasty has been introduced as
a new method to treat patients with severe heart failure. This procedure
consists of the wrapping of the latissimus dorsi (LD) muscle around the heart
with electrical stimulation of the muscle synchronous to cardiac contraction.
The optimal pacing mode of the muscle, during the conditioning and working
period of the LD muscle, is still unclear. The pace protocol, currently used
worldwide, has a maximal number of muscle tetanic contractions of 100 per
minute. Data are presented on the LD muscle contraction characteristics using
that protocol. Both force measurements from six in situ stimulated goat LD
muscles and x-ray evaluation of the movement of metallic clips on wrapped LD
muscles in two patients were used. Results demonstrate that LD muscle force is
well maintained at the maximal rate of 100 contractions per minute but
relaxation is severely hampered. This may lead to diminished support of the
failing heart and damage of the wrapped muscle. A pacing protocol is proposed
using a lower maximal stimulation rate
Lucas C.M., Van der Veen F.H.,
Cheriex E.C., Lorusso R., Havenith M., Penn O.C., and Wellens H.J. (1993)
Long-term follow-up (12 to 35 weeks) after dynamic cardiomyoplasty. J. Am. Coll.
Cardiol. 22, 758-767.
Abstract: OBJECTIVES. To obtain information on the long-term effects of dynamic
cardiomyoplasty on hemodynamics and muscle histology, this surgical method was
evaluated in goats. BACKGROUND. Dynamic cardiomyoplasty has been introduced as a
new method to treat patients with severe cardiac failure. METHODS. In 24 goats,
the left latissimus dorsi muscle was wrapped around the heart. The muscle was
then subjected to progressive electrical stimulation. In 16 goats, invasive
transesophageal Doppler echocardiographic measurements and histologic evaluation
of the latissimus dorsi muscle were performed at > or = 12 weeks after the
wrapping. RESULTS. Only two goats showed an increase in aortic and left and
right ventricular pressures concomitant with increased aortic flow during
latissimus dorsi muscle stimulation both before and after induction of cardiac
failure using imipramine. This was accompanied by a preserved latissimus dorsi
muscle structure and nearly complete transformation to type I muscle fibers. The
remaining 14 goats showed extensive lipomatosis in the latissimus dorsi muscle,
with severe intimal hyperplasia and proliferation of smooth muscle cells in the
walls of the thoracodorsal artery and its branches. An increase in endoneural
and endomysial connective tissue was observed, with some goats showing destroyed
nerve branches near the electrodes. These findings differed from those observed
after long-term electrical stimulation of goat latissimus dorsi muscle in situ.
CONCLUSIONS. Dynamic cardiomyoplasty is of use in the treatment of severe heart
failure if the histologic structure of the wrapped latissimus dorsi muscle
remains intact. Long-term results in goats suggest that the current approach
used in dynamic cardiomyoplasty may lead to deterioration of the wrapped muscle
Ma Y.G., Wang D.M., Li J.N.,
and Zhu H.Y. (1994) Cardiac function and histological changes after non-dynamic
cardiomyoplasty and preliminary study of dynamic cardiomyoplasty. Chin Med. J.
(Engl. ) 107, 836-839.
Abstract: By means of histological method and ultrasound cardiographic (UCG)
examination, the left-right ratio of transectional area of muscle fiber of
latissimus dorsi muscle (LDM) after non-dynamic cardiomyoplasty was 77.4 +/-
11.7% in Group I (3 weeks after operation), and 78.4 +/- 11.6% atrophy and
hyperplasia of LDM, but the basical structure was retained. The ejection
fraction (EF) decreased significantly after operation (P < 0.05), but the
difference between two groups was non- significant. Also, dynamic
cardiomyoplasty was performed on a sheep. UCG showed the increased cardiac
systolic function after operation. ATPase, succinodehydrogenase (SDH) and PAS
examination implied the strengthening of fatigue-resistant ability in skeletal
muscles after long-term electrical stimulation. So cardiomyoplasty is suggested
to be a supplementary measure in treating end-stage heart failure
Maillefert J.F., Eicher J.C.,
Walker P., Dulieu V., Rouhier-Marcer I., Branly F., Cohen M., Brunotte F., Wolf
J.E., Casillas J.M., and Didier J.P. (1998) Effects of low-frequency electrical
stimulation of quadriceps and calf muscles in patients with chronic heart
failure. J. Cardiopulm. Rehabil. 18, 277-282.
Abstract: PURPOSE: The aim of this preliminary study was to evaluate the effects
of low-frequency electrical stimulation of quadriceps and calf muscles on global
exercise capacities, skeletal muscle metabolism, calf muscle volume, and cardiac
output in patients with chronic heart failure. METHODS: Fourteen patients with
chronic heart failure (mean age of 56.4 years +/- 9.1 SD; mean radionuclide left
ventricular ejection fraction of 22.3% +/- 8.8 SD) underwent 5 weeks (1 hour per
day, 5 days per week) of low-frequency electrical stimulation of quadriceps and
calf muscles. RESULTS: Low-frequency electrical stimulation was well tolerated.
Exercise capacity and the calf muscles volumes increased significantly after
rehabilitation in comparison with prior rehabilitation (the peak oxygen
consumption increased from 17.2 mL/(kgmin) +/- 5.3 SD to 19.6 mL/(kgmin) +/- 5.9
SD; the anaerobic threshold increased from 12.3 mL/(kgmin) +/- 3.2 SD to 15.2 mL/(kgmin)
+/- 3.3 SD; the 6-minute walking test increased from 419 m +/- 122 SD to 459 m
+/- 114.3 SD; the gastrocnemius volume increased from 259.4 cm3 +/- 58 SD to
273.4 cm3 +/- 74 SD, and the soleus volume increased from 319 cm3 +/- 42.9 SD to
338 cm3 +/- 52.5 SD). The New York Heart Association class was improved after
rehabilitation. The P-31 nuclear magnetic resonance spectroscopy of
gastrocnemius muscle data were not significantly modified after rehabilitation,
thereby inferring that no significant improvement of the muscle metabolism
occurred. These data reinforce the hypothesis of an increased muscle mass during
stimulation. It is noteworthy that the electrical stimulation did not increase
cardiac output at any stage; an enormous asset in favor of this mode of
rehabilitation. CONCLUSION: These results suggest that low- frequency muscular
electrical stimulation is well tolerated, induces an increased exercise capacity
in patients with chronic heart failure, without an undesirable increase in
cardiac output
Malek A.M. and Mark R.G. (1989)
Functional electrical stimulation of the latissimus dorsi muscle for use in
cardiac assist. IEEE Trans. Biomed. Eng 36, 781-788.
Abstract: Direct and nondirect nerve stimulation modes of the thoraco-dorsal
nerve (TDN) leading to the latissimus dorsi muscle (LDM) were evaluated by using
nerve cuff electrodes (NCE) and intramuscular electrodes (IME), respectively.
Following electrode implantation, the LDM was chronically stimulated for two
months to induce muscle transformation to oxidative, fatigue-resistant type I
muscle fibers. Threshold and impedance values were measured regularly to
establish the stability of the implants. The LDM was then dissected, shaped into
a ventricle, subjected to a hydraulic load and stimulated using a
controlled-voltage pulse-train stimulator with adjustable parameters. Electrical
input and hydraulic output variables were measured to obtain the recruitment
characteristics and to compare the efficiency of the two types of electrodes.
Results indicate a tradeoff between the NCE's lower threshold, higher
recruitment, and lower energy consumption at saturation, and the IME's greater
mechanical stability and better long- term reproducibility
Mannion J.D. and Stephenson L.W.
(1985) Potential uses of skeletal muscle for myocardial assistance. Surg. Clin.
North Am. 65, 679-687.
Abstract: The potential for skeletal muscle to assist in cardiac function is
reviewed. Skeletal muscle can be transformed into a fatigue-resistant state
through chronic electrical stimulation. Thus it might be an ideal muscle for
replacing or augmenting failing heart muscle
Odim J.N., Li C., Desrosiers
C., Chiu R.C., O'Brien P.J., Hamilton N., and Ianuzzo C.D. (1991) The
remodelling of skeletal muscle for indefatigable hemodynamic work. Can. J.
Physiol Pharmacol. 69, 230-237.
Abstract: Skeletal muscle possesses inherent plasticity of gene expression. Low
frequency pulse-train stimulation can remodel the biochemical machinery that
confers physiological expression and fatigue resistance approaching that of the
myocardium. This fatigue-resistant muscle can generate sufficient force to meet
the power requirements for useful cardiac work. This ultimate goal is currently
being pursued in models of cardiomyoplasty and muscle-powered cardiac assist
devices. In this article, we review the three major subcellular systems
subserving canine skeletal muscle transformation and compare them to those of
cardiac muscle. The magnitude of the problem of clinical heart failure and the
feasibility of fatigue-resistant skeletal muscle joining the therapeutic
armamentarium are addressed. The adaptation and transformation of fast-twitch
skeletal muscle in response to chronic electrical stimulation augers therapeutic
potential as an endogenous, readily available power source for myocardial
assistance. The basis mechanisms of skeletal muscle fatigue require elucidation
to gain a complete and thorough understanding of how to manipulate this property
to provide continuous hemodynamic work
Oh J.H., Badhwar V., and Chiu
R.C. (1997) Hemodynamic response to in situ latissimus dorsi muscle stimulation:
implications in dynamic cardiomyoplasty. J. Card Surg. 12, 354-359.
Abstract: Dynamic cardiomyoplasty (DCM) involves the electrical stimulation of a
pedicled latissimus dorsi muscle flap wrapped around the falling ventricle as a
means of cardiac assist. To further elucidate a potential neurohumoral mechanism
for improvement of cardiac output after myoplasty, we evaluated the hemodynamic
effects of in situ stimulation of the latissimus dorsi muscle (in the absence of
cardiomyoplasty). In seven mongrel dogs, a nerve cuff electrode (Medtronic 6901)
was placed around the left thoracodorsal nerve (TDN). This was attached to a
pulse generator (Medtronic, Itrel 7420), delivering a 4.0 volt, 0.19 second on,
0.81 second off, 33 Hz, 210 microsecond pulse width, cyclic bursts similar to
that used in DCM. Stroke volume index (SVI) and other hemodynamic parameters as
well as plasma norepinephrine (NE) levels were measured at five stages:
baseline, stimulator on at 0, 2, and 5 minutes, and stimulator off at 30 minutes
after. The animals were then subjected to 4 weeks of rapid pacing at 240
beats/min (Medtronic 8329) to induce heart failure, and as the rapid pacing was
discontinued, measurements were repeated as above. After rapid pacing, cardiac
function was significantly depressed, and NE was elevated (133 +/- 69 versus 500
+/- 353 pg/mL, p < 0.05). In the normal hearts, TDN stimulation increased SVI,
heart rate, systemic pressure, and NE levels. In heart failure, however, no
significant changes in cardiac function and NE levels were noted. In conclusion,
our data indicate that in the normal hearts, afferent impulses from TDN
stimulation alone may augment cardiac function by means of a neurohumoral effect
that is not seen in severe heart failure. The implications of these findings in
DCM are discussed
Piluiko V.V., Knishov G.V.,
Riabinina L.G., and Krakovsky A.A. (1995) First experience with cardiomyoplasty
in Ukraine. Tex. Heart Inst. J. 22, 96-99.
Abstract: We have been studying feasible surgical alternatives for treating
congestive heart failure, including the use of cardiomyoplasty. In this
operation, skeletal muscles are conditioned, through electrical stimulation, to
provide active tension on diseased myocardium, which improves left ventricular
performance and ultimately increases cardiac output. We performed
cardiomyoplasty in a 37-year-old man with severe ischemic cardiomyopathy. He was
discharged from the hospital 2.5 months after the operation, and he did not
require medical therapy. We believe this to be the 1st cardiomyoplasty performed
in Ukraine
Quittan M., Sochor A.,
Wiesinger G.F., Kollmitzer J., Sturm B., Pacher R., and Mayr W. (1999) Strength
improvement of knee extensor muscles in patients with chronic heart failure by
neuromuscular electrical stimulation. Artif. Organs 23, 432-435.
Abstract: Patients with severe chronic heart failure (CHF) suffer from marked
weakness of skeletal muscles. Neuromuscular electrical stimulation (NMES) proved
to be an alternative to active strength training. The objective of this study
was to test the feasibility and effectiveness of NMES in patients with chronic
heart failure. Seven patients (56.0 +/- 5.0 years, CHF for 20 +/- 4 months, left
ventricular ejection fraction 20.1 +/- 10.0%) finished an 8 week course of NMES
of the knee extensor muscles. The stimulator delivered biphasic, symmetric,
constant voltage impulses of 0.7 ms pulse width with a frequency of 50 Hz, 2 s
on and 6 s off. No adverse effects occurred. After the stimulation period, the
isokinetic peak torque of the knee extensor muscles increased by 13% from 101.0
+/- 8.7 Nm to 113.5 +/- 7.2 Nm (p = 0.004). The maximal isometric strength
increased by 20% from 294.3 +/- 19.6 N to 354.14 +/- 15.7 N (p = 0.04). This
increased muscle strength could be maintained in a 20 min fatigue test
indicating decreased muscle fatigue. These results demonstrate that NMES of
skeletal muscles in patients with severe chronic heart failure is a promising
method for strength training in this group of patients
Quittan M., Wiesinger G.F.,
Sturm B., Puig S., Mayr W., Sochor A., Paternostro T., Resch K.L., Pacher R.,
and Fialka-Moser V. (2001) Improvement of thigh muscles by neuromuscular
electrical stimulation in patients with refractory heart failure: a
single-blind, randomized, controlled trial. Am. J. Phys. Med. Rehabil. 80,
206-214.
Abstract: OBJECTIVE: To determine the impact of an 8-wk neuromuscular
stimulation program of thigh muscles on strength and cross-sectional area in
patients with refractory heart failure listed for transplantation. DESIGN:
Forty-two patients with a stable disease course were assigned randomly to a
stimulation group (SG) or a control group (CG). The stimulation protocol
consisted of biphasic symmetric impulses with a frequency of 50 Hz and an on/off
regime of 2/6 sec. RESULTS: Primary outcome measures were isometric and
isokinetic thigh muscle strength and muscle cross-sectional area. Our results
showed an increase of muscle strength by mean 22.7 for knee extensor and by 35.4
for knee flexor muscles. The CG remained unchanged or decreased by -8.4 in
extensor strength. Cross-sectional area increased in the SG by 15.5 and in the
CG by 1.7. CONCLUSIONS: Activities of daily living as well as quality of life
increased in the SG but not in the CG. Subscales of the SF-36 increased
significantly in the SG, especially concerning physical functioning by +7.5
(1.3-30.0), emotional role by +33.3 (0-66.6), and social functioning by +18.8
(0-46.9), all P < 0.05. Neither a change nor a decrease was observed in the CG.
Salmons S., Vrbova G. (1969)
The influence of activity on some contractile characteristics of mammalian fast
and slow muscles. J Physiol 201, 535-549.
Salmons S., Sreter F.A. (1976)
Significance of impulse activity in the transformation of skeletal muscle type.
Nature 263, 30-34.
Salmons S., Jarvis J.C. (1992)
Cardiac assistance from skeletal muscle: a critical appraisal of the various
approaches. Br Heart J 68, 333-338.
Salmons P.H., Salmons S. (1992)
Psychological costs of high-tech heart surgery (guest editorial). Br J Hosp
Med 48, 707-709.
Salmons S. (1999) Permanent
cardiac assistance from skeletal muscle: a prospect for the new millennium.
Artif Org 23, 380-387.
Tang A.T., Jarvis J.C., Hooper
T.L., and Salmons S. (1998) Observation and basis of improved blood flow to the
distal latissimus dorsi muscle: a case for electrical stimulation prior to
grafting. Cardiovasc. Res. 40, 131-137.
Abstract: OBJECTIVE: Dynamic cardiomyoplasty, using a functional graft of the
latissimus dorsi muscle, has shown promise as a treatment for selected patients
with advanced heart failure. The success of this approach depends on maintaining
the viability of the muscle, whose distal portion is susceptible to ischaemic
damage. We investigated the effects of surgical mobilization on regional muscle
blood flow and the influence of electrical stimulation of the muscle. METHODS:
Ten sheep were randomly assigned to two equal groups. In one group, the
latissimus dorsi muscle was stimulated continuously in situ at 2 Hz for two
weeks; in the other group, the muscle was not stimulated. Regional blood flows
in the muscles were determined by a fluorescent microsphere technique. Serial
measurements were made (a) under baseline conditions before intervention, (b)
with the thoracodorsal artery occluded and (c) after interruption of the
perforating collateral arteries. RESULTS: Surgical mobilization of the
unstimulated latissimus dorsi muscles had little effect on blood flow in the
proximal region, which remained at 93.1 +/- 16.9% of baseline (mean +/- SEM).
The distal region was rendered significantly more ischaemic (55.8 +/- 13.5% of
baseline, p < 0.002 compared to the proximal region). Electrical prestimulation
abolished any significant proximodistal gradient in blood flow and improved
distal muscle perfusion following mobilization (proximal vs. distal: 75.0 +/-
8.8 vs. 63.0 +/- 10.9%; p > 0.4). CONCLUSIONS: Distal muscle ischaemia occurred
when the entire latissimus dorsi muscle was acutely elevated on the
thoracodorsal pedicle alone. Electrical prestimulation of the muscle in situ
improved the thoracodorsal perfusion of the distal muscle by abolishing the
proximal-to-distal gradient in flow, with a substantial benefit to distal flow
after mobilization. Although electrical stimulation is known to induce vascular
proliferation, we argue that this effect of stimulation is brought about mainly
by enhancement of the flow through anastomotic connections between proximal and
distal arterial territories
Tang A.T., Jarvis J.C., Hooper
T.L., Salmons S. (1999) Cardiomyoplasty: the benefits of electrical
prestimulation of the latissimus dorsi muscle in situ. Ann Thorac Surg
68, 46-51.
Thelin S., Vedung S., Nylund
U., and Thorelius J. (1992) Experimental dynamic cardiomyoplasty in sheep.
Scand. J. Thorac. Cardiovasc. Surg. 26, 1-7.
Abstract: To evaluate electrically stimulated muscle grafts for augmenting
ventricular function in cardiac insufficiency, dynamic cardiomyoplasty was
performed in nine sheep, using latissimus dorsi (LD) muscle wrapped as a pedicle
around the left ventricle. Beginning 2 weeks postoperatively, LD was stimulated
synchronously with the heart. After 6 and 12 weeks of stimulation, hemodynamic
evaluation was done and biopsies were taken for histochemical and biochemical
analysis. With intact heart function, stimulation of the muscle was not
hemodynamically beneficial. During induced heart failure, cardiomyoplasty
increased cardiac output by 25% in two sheep. Eight LD muscles contracted
vigorously in synchrony with the heart, one was fibrosed and all were fixed to
the thoracotomy incision by scar tissue. ATPase stain showed gradual
transformation of muscle fibers into fatigue-resistant Type I. At 12 weeks only
Type I were seen. Quantitative enzymatic analyses revealed increase in oxidative
and decrease in glycolytic enzymes. Chronic electrical stimulation is concluded
to change the muscle characteristics towards those of mainly oxidative and
fatigue-resistant muscle, thereby improving opportunities for assisting the
depressed heart.
Thomas G.A., Isoda S., Hammond
R.L., Lu H.P., Nakajima H., Nakajima H.O., et al (1996) Pericardium-lined
skeletal muscle ventricles: up to two years’ in-circulation experience. Ann
Thorac Surg 62, 1698-1706.
Thomas G.A., Baciewicz F.A.
Jr., Hammond R.L., Greer K.A., Lu H., Bastion S., et al (1998) Power output of
pericardium-lined skeletal muscle ventricles, left ventricular apex to aorta
configuration: up to eight months in circulation. J Thorac Cardiovasc Surg
116, 1029-1042.
Thomas G.A., Hammond R.L.,
Greer K.A., Lu H., Jarvis J.C., Shortland A.P., et al (1999) Functional
assessment of skeletal muscle ventricles after pumping for up to four years in
circulation. Ann Thorac Surg.
Thomas G.A., Hammond R.L.,
Greer K., Lu H., Jarvis J.C., Shortland A.P., Pullan D.M., Salmons S.,
Stephenson L.W. (2000) Functional assessment of skeletal muscle ventricles after
pumping for up to four years in circulation. Ann Thorac Surg 70,
1281-1289.
You J.M., Landymore R.W., and
Fris J. (1997) Delayed stimulation of the latissimus dorsi may result in disuse
atrophy. Ann. Thorac. Surg. 64, 404-408.
Abstract: BACKGROUND: The latissimus dorsi is usually left unstimulated for 2
weeks after cardiomyoplasty to allow the muscle to recover from the loss of the
collateral circulation. To determine whether the 2-week delay may cause muscle
atrophy, we randomized 15 mongrel dogs to a control group or a disuse atrophy
group. METHODS: The collateral circulation to the latissimus dorsi was ligated
in all animals before cardiomyoplasty to reduce the risk of ischemic injury to
the muscle during mobilization. Two weeks after collateral ligation, the atrophy
group had the tendinous attachment of the latissimus dorsi severed and then 2
weeks later underwent cardiomyoplasty. The control group had a 2- week delay
after collateral ligation followed by cardiomyoplasty. Biopsies were performed
before collateral ligation and before cardiomyoplasty. After heart failure was
induced, hemodynamic function was assessed during synchronized contraction of
the latissimus dorsi by measuring the maximum systolic elastance, stroke volume,
preload recruitable stroke work index, and diastolic compliance. RESULTS:
Comparison of muscle morphology between the two groups demonstrated the presence
of muscle atrophy in those animals that had been randomized to the atrophy
protocol. During synchronized contraction of the latissimus dorsi, there was no
significant increase in maximum systolic elastance in either group. However,
both stroke volume and pulmonary recruitable stroke work index were
significantly higher in the control animals during assisted beats. The left
ventricle was less compliant in the atrophy group, suggesting that muscle
atrophy had adversely affected diastolic function. CONCLUSIONS: Delayed
electrical stimulation of the latissimus dorsi may result in atrophy and loss of
function
|
