|
Dynamic support to heart failure |
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Jacques
De Paepe |
Introduction
Heart
failure is a clinical syndrome that arises when the heart is unable to
pump sufficient blood to meet the metabolic needs of the body at normal
filling pressures, provided the venous return to the heart is normal.(
Hurst’s The Heart, ninth edition, page 687). The terms “myocardial failure”, “heart failure” and circulatory failure are not synonymous. (Brauwald’sHeart Disease, fifth edition, page 394). Heart
failure may be acute or chronic. High
wall tension and stretch on the epicardial vessels making perfusion
indetectable.
Some
Dates
1952
heart-lung machine (Gibbon) Review
of some recent publications
Surgical
therapy
CABG Coronary
artery bypass grafting can be offered to patients with ishemic left
ventricular failure at a low operative risk (2%) and with a satisfactory
long-term outlook. Despite satisfactory early and late survival, late
functional outcome after myocardial revascularization in ischemic
cardiomyopathy remains suboptimal because of recurrence or persistence of
congestive failure (2). Mitral
valve surgery Between
1990 and 1998, 44 patients with mitral regurgitation and a LV ejection
fraction <35% underwent isolated mitral repair (n=35) or
replacement….. Every patient had been hospitalised one to six times for
symptoms of heart failure….Postoperative mortality: 2,3%. The 1, 2 and 5
year survival rates were 89, 86 and 67% respectively. Freedom from
readmission for heart failure was 88, 82 and 72% at 1, 2 and 5 years
respectively No patient has been listed for transplantation. Mitral valve
surgery offers symptomatic improvement and survival benefit in patients
with severe LV Dysfunction and mitral regurgitation. More liberal use of
this surgery for cardiomyopathy patients is warranted. Dr
Turina: In
our experience, long-standing mitral regurgitation leads to a progressive
fibrosis of the left ventricule and valve surgery has less than optimal
results if the patient has been symptomatic for a long time (3). Mitral
regurgitation is a significant complication of end-stage cardiomyopathy,
thought to be to dilatation of the mitral annular-ventricular apparatus
with altered ventricular geometry or due to ischemic papillary muscle
dysfunction. Mitral regurgitation leads to a cycle of more volume overload
of the already dilated left ventricle
with progressive annular dilatation, worsened mitral regurgitation,
and congestive heart failure. 16
patients, aged 44 to 78 years (64~8years)with left ventricular ejection
fraction of 9% to 25%. No operative or hospital death.One year survival:
75%.(5). Ventricular
scare resection (partial ventriculectmy or endoventricular circular patch) The
Dor operation is the primary choice for ischemic cardiomyopathy(1). Large
akinetic scar (n=51) or large diskinetic scar (n=49) and depressed
ventricular function (ejection fraction <30%). Coronary grafting were
performed in 98% of patients; 10 mitral valve repair or replacement. Forty
seven patients with preoperative ventricular arrhythmias had cryotherapy.
In hospital mortality was 12%. Results showed an early and late
improvement in functional class and ejection fraction. Ventricular
tachycardia reduced significantly. Ventricular
repair is technically more difficult in the akinetic heart, in which the
shape is abnormally altered and global function is very depressed. These
changes develop because the limit between scar and normal tissue is not
clearly defined when the trabecular scar is not cicumferential.
Consequently, the placement of the patch is left to the surgeon’s
judgment (6). Heart
transplant The number of patients with heart failure is steadily increasing with an estimated 400,000 new cases recorded annually in the United States . Ninety percent of lethal outcomes are due to cardiac causes: 30,000 (upper age limit of 75 years)-60,000(upper age limit of 85 years) persons die of heart failure in the US each year and about 4.000 new patients are listed for cardiac transplantation (2,500 receiving a transplant). (28) (50). …In
a further study of 130 patients awaiting transplantation, 1-year survival
was only 45%. Significant predictors of death…were low forward stroke
volumes, an ejection fraction less than 25% and mitral regurgitation (5). In
practice, transplantation is somewhat uncommon because of (1) the reduced
donor/need ratio and (2) the fact that many patients with advanced age,
pulmonary hypertension, renal insufficiency and diabetes have
unsatisfactory late results.(6). The
risk factors for graft failure are : recipient age > 50 years,
pre-operative ventilatory support, pre-operative circulatory support,
>& previous sternotomy, pulmonary resistance > 2,5 Wood units,
male with body surface > 2,5 m², retransplant, ischaemic time >
3.5h, donor age > 45 years, donor inotropic support > 10 gamma/kg
per min dopamine, female donor, ratio donor/recipient body surface area
< 0.7, donor with diabetes and history of donor drug abuse. The 30-day
survival for the risk groups was low: 97%, moderate: 95%, High: 87%.(7). The
actuarial survival in the cyclosporine + OKT3 group is 70% at 5 years and
50% at 10 years. The incidence of graft coronary artery disease has
progressively decreased. This disease process may have been stabilized or
retarded by the use of diltiazem and lipid-lowering agents.(8). Cardiomyoplasty Mortality
by dilated cardiomyoplathy in the first year after diagnostic ranges from
20% to 50%. In the Framingham study, the survival rate of the patients who
developed congestive heart failure was 50% after 5 years. In hospital
series, the death rate was 50% in the first year. Furthermore, the life
quality of such patients was severely hindered. No operative death. In the
nonchagasic group, the survival rates after cardiomyoplasty were 50% and
15% at 60 and 110 months of follow-up. There was no correlation between
the clinical improvement and hemodynamic data. Ventricular fibrillation
was a frequent cause of immediate and late death, suggesting the need for
prophylactic use of antiarrhythmic drugs or implantable cardioverter/defibrillators.
(9) Biventricular
failure was emphasized as a contraindication for cardiomyoplasty in the
study by Carpentier and colleagues. We routinely inserted an IABP just
after the induction of anesthesia. IAB counterpulsation lasted 1 or 2 days
after the operation. Thirty-day mortality rate was 21%. Concomitant
coronary revascularization, a preoperative left ventricular ejection
fraction below 20%, and a functional capacity of class IV (intermittently)
were associated with early mortality. Survival analysis revealed no
difference between the ischemic and idiopathic groups. Functional status
improved in the both groups. Ejection fractions were improved after
cardiomyoplasty in all patients, regardless of their cause. (10). The
mean NYHA functional class improved postoperatively from 3.2 to 1.8.
Average radioisotopic left ventricular ejection fraction increased
from 17 to 27%. Following cardiomyoplasty, the number of
hospitalisations due to congestive heart failure was reduced to 0.4
hospitalizations/patient per year (preoperative: 2.5). Seven % underwent
heart transplant after cardiomyoplasty. There were no specific technical
difficulties. Cardiomyoplasty may delay or prevent the progression of
heart failure and the indication of cardiac transplantation. (11). Benefits
from dynamic cardiomyoplasty are by at least two mechanisms: 1) the
girdling effects of a conditioned muscle wrap, which halts the chronic
remodelling of heart failure, and 2) active systolic assistance, which
augments the apparent contractility of the failing heart (experimental
work on chronic canine model of dilated cardiomyopathy).(12). 127
consecutive patients in 3 centers. Operative mortality was 12%. Survival
at 5 years was 40%. There was a distinct improvement at 6 months in NYHA
functional class (3.2 vs 1.7) and a small but significant increase in left
ventricular ejection fraction (20% vs 23%). Ninety-day mortality was
associated with low right ventricular ejection fraction, a blunted
hemodynamic response to exercise testing, and requirement for an
intraaortic balloon pump at the time of the operation. Low preoperative
oxygen consumption on exercise testing, atrial fibrillation, NYHA class
IV, high pulmonary capillary wedge pressure and balloon pump use were
independent variables simultaneously associated with poor overall
survival.(13). Aortomyoplasty In
5 alpine goats the right latissimus dorsi muscle was used to achieve a
wrap around the ascending aorta, which
had been augmented with a elliptical pericardial patch. Electrostimulation
protocols were commenced after 2 weeks and continued for 12 to 24
months.After induction of cardiac depression there was a 52% increase in
cardiac output, 39% decrease in systemic vascular resistance, and 27%
increase in subendocardial viability index. Since November 9, 1992 (to
1995), the date of the first aortomyoplasty case performed at Broussais
Hospital, 14 aortomyoplasty procedures have been performed worldwide.(14) Six
mongrel dogs underwent a staged operation in which the left latissimus
dorsi was conditioned in situ for 4 weeks, then wrapped around the
descending aorta and stimulated during diastole with each cardiac
contraction. Aortomyoplasty has beneficial effects on ischemic left
ventricular contractility, and may therefore be useful for treating
inoperable coronary artery disease.(15). Ventriculectomy
(Batista) The
extend of myocardial disease is not homogeneous. Sometimes part of the
posterior wall is diseased, and sometimes part of the septum. We have to
know the extend of the lesion and viability before selecting the
procedure. Therefore we introduced the intra-operative echo-guided volume
reduction test as a sort of viability provocation. It is impossible to
know the actual thickness of the left ventricular wall before the
operation, because most of the left ventricular wall of dilated heart
looks very thin by echocardiography. For one thing, it is already fibrotic
or just stretched, but we cannot tell the difference unless we reduce wall
tension. Fortunately, we can do it during the operation by left
ventricular decompression on the pump, and we can have the information
before we cut the left ventricle. Then we can decide whether to do an
annuloplasty alone or whether to cut somewhere….However it is important
not to make the heart too small. (1). Hospital
mortality in elective and emergency operations
was 0% and 50% with no late death (1). Non-ischemic
cardiomyopathy, 17 patients who survive to partial left ventriculectomy:
relations between LV shape and functional satus. Mitral repair or mitral
replacement were performed in all the cases….We confirmed that
ventricular redilatation occurs in all patients, irrespective of their
functional status. On the other hand, we found a gradual increase of
end-systolic stress in non-responders only Mitral repair or mitral
replacement were performed in all the cases….showing a similar trend.
Interestingly, the postoperative LV geometry in the two groups was
different despite the fact that in all of them the same type of
reconstruction was attempted. Our data show a late decrease of LV ejection
fraction in a high-preload group of non-responders, and its preservation
in a low-preload group of responders. The refinement of surgical technique
is desirable, with the goal of making LV as elonged as possible. A
computer simulation study noted a greater effect of lateral as opposed to
apical ventriculectomy.(16) Baby
operated (partial left ventriculectomy and heterotopic heart
transplantation) at the age of 4 months and doing well 12 months
after.(17). Only
1 patient (of the PLV group) did not have mitral regurgitation before the
operation; the remaining 15 patients all had significant mitral
regurgitation and were treated at the time of the operation. Operative
survival was 94% after partial left ventriculectomy and 94% after heart
transplantation. Post-operative Kaplan-Meier survival was 86% after
partial left ventriculectomy and 93% after heart transplantation. Twelve
month Kaplan-Meier survival after listing for heart transplantation was
75% due to death while on the waiting list. Freedom from death or need for
relisting for heart transplantation was 56% after partial left
ventriculectomy and 86% after transplantation. Although partial left
ventriculectomy is associated with acceptable operative and 12 month
survival, it may prove to serve better as a bridge to transplantation in
patients with idiopathic dilated cardiomyopathy rather than definitive
therapy, given the number of patients who required relisting for
transplantation. As time as progressed,we refined our approach and we are
currently looking at other indices that may suggest a better long-term
result after PLV. Specifically, we are looking at the amount of myocardial
fibrosis and myocyte diameter on endomyocardial biopsy and response with
dobutamine echocardiography. We are less likely to advice patients with
little improvement on dobutamine echocardiography, with myocyte diameter
greater than 30mm, and with significant fibrosis to undergo PLV. (18). The
procedure consisted of removal of a wedge of left ventricular muscle from
the apex to the base of the heart. Depending on the distance between the
two papillary muscles, the mitral valve apparatus was either preserved,
repaired or replaced with a tissue prosthesis. The 30-day mortality was
22%, and the 2-year survival was 55%. Although 10% of surviving patients
showed no improvement in NYHA functional class, most of surviving patients
were in either class I (57%) or II (33,3%° and the others were in class
III and IV.(19). Cardiac
transplantation is an established treatment for end-stage heart failure.
However, is it not widely available because a shortage of donors and, in
parts of the world, societal limitations. The
factors influencing the surgical results for dilated cardiomyopathy were
presence of severe mitral regurgitation, preoperative New York Heart
Association functional class IV with emergency operation, and operative
procedures with randomly partial left ventriculectomy without an intraoperative
echo test. The selection of operative procedures in idiopathic dilated
cardiomyopathy and avoidance of emergency surgery improved operative
mortality and morbidity. In emergency operations for patients with ongoing
shock, partial left ventriculectomy is associated with a extremely high
risk. Treatment with a left ventricular assist device, if available,
should be considered initially.(1). Myocyte
transplant Myocardial
infarction was created in rats. One week later the animals were
intramyocardially injected with culture growth medium alone, fetal
cardiomyocytes or neonatal skeletal myoblasts and were immunosuppresed.
Left ventricular function was assessed by echocardiography immediately
before transplantation and 1 month thereafter. The left ventricular
ejection fraction markedly increased in the fetal and myoblast groups from
39% to 45%nand from 40% to 47% respectively whereas it decreased in
untreated animal from 40% to 36%.(21). Smoth
muscle cells were isolated from the ductus deferens of 13-weeks-old
hamsters with dilated cardiomyopathy, and cultured for 4 weeks before
transplantation. Culture medium were injected into 17 weeks old animals in
control group. Four weeks after transplantation, heart function was
evaluated in a Langendorff apparatus. Conclusion: transplantation of
autologous smooth muscle cells prevent cardiac dilatation and improved
ventricular function. Will
we have to add something such as an angiogenesis-type agent? Fortunately,
the transplanted cells induce angiogenesis by releasing a variety of
factors. In addition our smooth muscle cell cultures also contain
endothelial cells, which can participate in the formation of new
capillaries. We can enhance the angiogenesis by transferring the cells
with a plasmid which will produce vascular growth factor (VEGF). Only a
few cells divided after transplantation and all cells divided in
vitro.(22). Soleus
skeletal myoblasts were expanded in vitro from adult rabbits whose
posterior left ventricle was cryoinjured to create a transmural lesion.
Autologous myoblast or saline was transplanted into the central cryolesion
at the time of injury or 1 week later. Hearts were harvested 2 weeks
after. In saline-injected hearts contained no viable cardiomyocytes. In
myoblast-injected group, elonged structures closely resembling
multinucleated skeletal myotubes covered up 75% of the central cryolesion. In
the early embryo, fetal cardiomyocytes differenciate before the progenitor
mesenchymal cells give rise to skeletal myoblasts. The microenvironment
may modulate the differentiation pathway of myoblasts to exhibit either
skeletal or cardiac muscle phenotypes. (23). Devices IABP An
ascending aorta-coronary bypass graft (ACB), an internal thoracic artery,
and a descending aorta-coronary bypass graft were anastomosed to the left
anterior descending coronary artery in a canine model: the blood flow to
the same coronary bed in the three types of grafts could be evaluated. In
the control study, the diastolic flow decreased in the following order:
with the ACB, the internal thoracic artery, and the descending
aorta-coronary bypass graft. Use of IABP increased the diastolic flow by
75% of the control value in the ACB, 38% in the internal thoracic artery
and 21% in the descending aorta-coronary bypass graft. The LVAD (employed
synchronously with cardiac cycle by counterpulsation) increased the
diastolic flow by 97% of the control value in the ACB, 64% in the internal
thoracic artery, and 63% in the descending aorta-coronary bypass graft. Arterial
grafts originating from a systolic-dominant circulation distant from the
heart, compared with the ascending aorta-originated grafts, have some
limitations in their ability to supply blood to the diastolic-dominant
coronary circulation. Multiple revascularizations using only in situ
arterial grafts may cause hypoperfusion even with left ventricular
support, especially in the presence of left ventricular dysfunction. (24). Ventricular
assist devices Since
June 1994 (to April 2000), 84 patients with end-stage end-stage heart
failure were supported with either a Novacor or a Heart Mate left
ventricular device. Of this cohort, 65 patients had IDC, and 19 had
ischemic cardiomyopathy. Patients with ischemic heart disease were
excluded from the study. Of the group of IDC, 23 underwent removal of the
LVAD when cardiac function had undergone complete or near complete
restoration during a decompression period of between 30 and 794 days. The
42 patients with IDC who did not attain cardiac functional improvement to
near normal values were also excluded from the study. At the time of
implantation, the patients had invariably reached a state of
conventionally untreatable heart fealure, and they were receiving
intravenous inotropic medication, predominantly dopamine and dobutamine,
which in some instances was combined with phosphodiesterase inhibitors or
epinephrine. Hemodynamic data revealed elevated pulmonary artery pressures
and a depressed cardiac index LVIDd that ranged from 62 to 92 mm and
severely impaired ventricular function with LVEF data of between 10% and
20%. Implantation of an LVAD was decided on as an emergency procedure in
all patients, with the primary goal of keeping the patient alive. The
prospect of electice pump explantation was taken into consideration when,
on repeated investigation, the LVIDd had dropped below 60mm and the LVEF
had risen to more than 40%. After explantation, the patients began taking
anticoagulants for 6 months, beta-blocker, angiotensin-converting enzyme
inhibitors and aldosterone antagonists. Seven patients had recurrent heart
failure 4 to 24 months after pump explantation. Six of these underwent
heart transplantation between
4 and 17 months after removal of the assist device. Four patients died of
causes unrelated to heart failure. The age at the time of device placement
was the only influencing factor for duration on the assist device. The
probability of recurrence of heart failure was influenced by the duration
of heart failure. Of
approximately 230 patients we have treated by assist device implantation
during this time span, 136 had IDC. About 10% of them had a successful
long-term recovery after explantation. When we consider only those who had
an apical drainage pump, which I personally believe is an essential
perequisite for recovery, then this proportion might be 20%. (25-26). LVAD
(HeartMate) explantations in 6 patients, out of approximately 170 LVAD
implantations; 2 have heart failure recur (and successful
transplantation). (46). We
assessed clinical outcome of 64 consecutive patients (1.5% of pump cases
between 1984 and 1997) who
had temporary circulatory support. The discharge rates were 26% with
venoarterial bypass, 57% with biventricular bypass, 37% with isolated left
ventricular bypass and 40% with pulsatile left ventricular assistance.
Logistic regression analysis identified presupport cardiogenic shock,
support duration and support type associated with mortality during or after the circulatory
support. In 42 patients on temporary support for less than 24 h hours, 47%
were discharged from the hospital. In contrast, 20% of 5 patients on
support for over were alive and discharged from the hospital. Severe hypotension less than 70 mmHg or ventricular
fibrillation was defined as presupport cardiogenic shock. Of 25 patients
who received circulatory support after profound cardiogenic shock, only 1
patient (4%) was alive without brain dommage and discharged from the
hospital. Of 39 patients without cardiogenic shock, 62% survived.
Massive bleeding and malignant ventricular arrythmia were less
frequent with low-heparinized isolated left ventricular support 5LVB or
LVAD). However, intractable biventricular failure, infection and multiple
organ failure still remain significant complications with any type of
circulatory support. We suspect that patients who died during or after
some type of temporary support might have been saved by earlier or more
appropriate conversion to other types of circulatory support. From
the information in the combined registry (ASAIO-ISHLT),, 1,279 patients
had temporary circulatory support after cardiac operation (1994-1999); 25%
were discharged from the hospital.(27). A
patient (54 years) with ischemic cardiomyopathy and extremely reduced left
ventricular function (LVF = 0.10) presented to our institution for cardiac
transplantation. Cardiac index was calculated as 1.3 l:min:m², pulmonary
hypertension with a mean pressure of 45mmHg, a pulmonary vascular
resistance of 8 Wood units. Scintigraphy showed no viable myocardium.
Because his worsening conditition he was placed on the Novacor left
ventricular assist device. During “ months of support his left
ventricular function recovered and he successfully underwent percutaneous
transluminal coronary angioplasty and minimal invasive direct coronary
artery bypass grafting procedures (“hybrid procedure”); subsequently
he could be weaned from the left ventricular assist device and discharged.
The patient is no longer considered for cardiac transplantation. (29). Forty-four
patients who had circulatory assist devices (32 Thoratec, 11 Novacor, 2
Jarvik) placed as a bridge to transplantation (between May 1985 and April
1993). Fifteen patients did not receive a donor organ (10 infections, 9
bleedings, 5 renal failure, 3 cerebrovascular accidents, 1 ventricular
fibrillation and 1 right heart failure) and died. Twenty-seven underwent
transplantation (1 post-operative and 4 late deaths). Two patient were
weaned from support and survived without transplantation. Two patients
were encountered who had patent foramen ovale. In one the defect was
detected by palpation and closed before insertion of the VAD. In the other
it was detected after insertion of a left VAD and closed in the operating
room after the patient became cyanotic. The hospital survival of greater
than 96% in this series is primarily attributable to our insistence on
performing transplantation only in patients whose organ dysfunction had
been reversed, whose nutrition was improved, and in most the cases who
were ambulant with improved exercise tolerance compared with their
preimplantation state. These “rehabilitated” patients were excellent
candidates for transplantation. (30). Biomedicus Since
January 1989 (to April 2000) 62 patients were supported with centrifugal
pumps because of failure to wean from cardiopulmonary bypass (0,5% of
patients who had surgical procedures).As a rule, candidates for VADs were
less than 80 years old and had no coexisting medical problems (dialysis
dependency, malignancy,…). All had intraaortic balloon pump in place.
The indications were postcardiotomy cardiogenic schok (60), bridge to
cardiac retransplantation (1), cardiac right failure after a pulmonary
embolectomy(1). Thirty-tree (50%) had a biventricular assist device, 22
(35%) had a left ventricular device,
9 (15%) a right. Twenty-seven (44%) survived to discharge from the
hospital. The most prevalent complications were bleeding (42%), renal
failure (28%) and respiratory failure (26%). Of
critical importance in the initial stage of postcardiotomy failure is
early implantation of ventricular assistance, insertion of an intraaortic
balloon pump to maintain pulsatile perfusion, and supporting the right
ventricle. Several
disadvantages are associated with centrifugal pumps. Primary, there is the
need for intraaortic balloon pumping to obtain a pulsatile flow pattern.
In addition, centrifugal pumps provide a limited length of circulatory
support (maximum 2 weeks). Patients cannot be ambulatory and are at risk
of developing respiratory and renal problems, infection and thrombolysis.(31)
From
January 1986 to September 1995, 141 patients were placed on the Biomedicus
centrifugal pump after postcardiotomy cardiac failure. Left ventricular
assistance was provided in 110 patients, biventricular assistance in 23
patients, right ventricular assistance in 8 patients. In 70% of the
patients the intra-aortic balloon was inserted (because of unsatisfactory
vascular access, some patients cannot be supported with the intraaortic
balloon pump; these patients have non pulsatile blood flow, and a few have
been supported for more than 1 week with evidence of adequate organ
perfusion). To minimize third space fluid accumulation, we normalize
colloid oncotic pressure, avoid excessive crystalloid administration and
utilize hemofiltration. Carmeda circuits are used so that continued
heparinization after implant is not required. Only 22% survived to
discharge. In patients who have had postcardiotomy support, avoiding fluid
overload, low colloid oncotic pressure, hypoperfusion, and use of
excessive inotropic and vasoactive medications improve results.(32). Forty-two
children (aged 2 days-13 years) undergoing
elective cardiac surgery were assigned to either centrifugal or
roller pump bypass. The centrifugal pump resulted in lower plasma free
haemoglobin, higher platelet count, less platelet activation,. Differences
were detected in favour of the centrifugal pump in urine output on bypass,
post-operative maximal urea, ventilation time, duration of intensive care,
and hospital stay, but not in blood and blood products requirements. (33). Three
infants, less than 10 kg in weight, with severe left ventricular
dysfunction following cardiopulmonary bypass have been manage
with a left ventricular assist device (Biomedicus)). One made a
complete recovery. Another sustained massive neurological damage. The
third died of progressive left ventricular dysfunction.(34) Hemopump Several
studies showed that mechanical support reduces myocardial oxygen
consumption and infarct size and enhances myocardial recovery after
stunning. The
Hemopump is a miniaturized rotary blood pump mounted on a catheter. The
bedside console allows regulation of the pump speed from 17,000 to 26?000
rotations per minute. Once the canula is inserted over the aortic valve,
it sucks the blood out of the left ventricle and expels it into the
ascending aorta. The femoral cannula is less performant (maximum flow of
3,5 l/min) than the transthoracic (5l/min). The non-pulsatile flow
delivered by the Hemopump device is continuously influenced by the
underlying cardiac activity. From
1989 to 1997, 61 patients with postcardiotomy left ventricular failure
beyond intra-aortic balloon pumping were assisted with the Hemopump
cardiac assist system (12.129 cardiac surgery in the same period, 388
(3,2%) IABP, 108 (0.9%) VAD in total ). Forty-seven % underwent cardiac
massage before pump support and evolving myocardial infarction was
diagnosed in 43% before surgery. There is a striking difference in
occurrence of device-related complications between the femoral device
(problems of cannula introduction and drive cable fracture) and the
transthoracic pump. Bleeding occurred in 13% of
the patients. Only 37% were discharged home. (35). Twelve
sheep underwent implantation of a transthoracic Hemopump device and an
intraaortic balloon pump. The association of balloon counterpulsion with
the Hemopump device reduces the Hemopump output by 11%. After application
of coronary stenosis, support with the Hemopump device alone improved the
ratio of subendocardial to subepicardial blood flow, but endocardial
underperfusion remained. The Hemopump device with an intraaortic balloon
pump completely restored perfusion in poststenotic regions. (36). From
1992 to 1994, 15 patients received a Hemopump 31 (sternotomy Hemopump).
All suffered postcardiotomy cardiogenic shock. Mean wedge pressure dropped
from 23mmHg to 9 mmHg and patients only received dobutamine at 6
gamma/kg/min to enhance the right ventricular function. The survivors did
not require the aid of vasopressors to maintain their main arterial
pressure. Mortality with double Hemopump (right and left): 100%; with
delayed insertion after intra-aortic balloon pump failure: 75%; with
immediate insertion: 45%. Early use after onset of heart failure achieves
better results. (37). Over
a two years period 21 (0.8%) of 2,585 patients undergoing cardiac
operations needed a ventricular assist device because of postcardiotomy
heart failure unresponsive to pharmacologic and intraaortic balloon
support. The aim was myocardial recovery as the underlying conditions
(age, arterial hypertension, diabetes, vascular and pulmonary disease)
excluded heart transplantation. During weaning the Hemopump was reduced to
its lowest speed but never turned off, as a completely stopped Hemopump
induces serious aortic insufficiency. Four (25%) were discharged. Left
ventricular hypertrophy is a relative contraindication for the use of the
Hemopump. (38). Percutaneous
transluminal angioplasty of the left anterior descending coronary artery
was attempted. Unfortunately, the procedure was complicated by main
dissection, and cardiac arrest ensued. The patient was successfully
resuscitated, and a Hemopump assist device was placed through a left
femoral approach in the catheterisation laboratory. As soon as the device
was started the patient regained consciousness. After a few minutes of LVA
in cardiac arrest, intractable ventricular fibrillation ensued. However,
the patient’s hemodynamic and neurologic condition remained stable. He
was transferred to the operating theatre. One month later, the patient had
a small antero septal cicatricial myocardial infarction. Nevertheless,
left ventricular function remained with is normal limits. (39). Abiomed Abiomed
BVS (75 patients) and Thoratec VAD (103 patients) have been applied for
postcardiotomy failure or as bridge-to-transplant procedure. Patients with
early postcardiotomy heart failure are initially scheduled for Abiomed
support, because implantation in the operating room is easy and pump does
not require special post-operative care. In patients with late
postcardiotomy failure (implantation on the intensive care unit) we prefer
centrifugal pump assistance, because it can be inserted without the
institution of extracorporeal circulation. In postcardiotomy patients with
a preoperatively reduced ejection fraction in which the heart is unlikely
to recover, the implantation of the Thoratec VAD is recommended, provided
there is no contraindication for cardiac transplantation. In transplant
candidates needing biventricular mechanical circulatory support as a
bridging procedure the Thoratec device is selected because it is more
suitable for an extended duration of support than the Abiomed system,
providing a certain degree of mobility for the patients. In the Abiomed
collective, 25 of 50 patients (50%) with postcardiotomy heart failure and
1 of 4 patients with miscellanous other indications could be discharged
from hospital; 7 of 14 bridge-to-transplant patients (50%) underwent
transplantation with a post transplant survival of 86%. In the Thoratec
collective 6 of 10 patients (60%) with postcardiotomy heart failure and 4
of 8 patients (50%° with miscellanous indications could be discharged
from hospital; 48 bridge-to-transplant patients (74%) underwent
transplantation with a post-transplant survival of 90%. Although in case
of postcardiotomy heart failure, Thoratec is also superior to Abiomed (the
Thoratec system offers the possibility of long-term use with lower
morbidity and provides more pump output – 3.8 vs 4.3 l/m² - and mobility for the patient), the high costs of the Thoratec
VAD limits its wide acceptance in this patient cohort. (40) In
3 years, 22 patients were supported with the Abiomed BVS 5000 (postcardiotomy
support: 12 (50% discharged), bridge to transplant: 4 (75% discharged),
failed heart transplant: 4 (50% discharged), acute myocarditis: 2 (100%
discharged)). The patients were selected by hemodynamic criteria (propsed
by Norman in 1973): systolic
blood pressure less than 80-90, left or right pressure greater than
20mmHg, low cardiac index (<2l./min/m²). Because the Abiomed was
readily managed by the intensive care unit staff and the centrifugal pump
by the perfusionist team (there were times when the lack of sufficient
perfusion staff resulted in limitation of the routine operating room
schedule, creating a hidden cost by idling other specialized personnel),
this system is less expensive than the second one. (41). The
blood pumps are extracorporeal and sit at the bedsite on a intravenous
pole. Filling can be altered by adjusting the level of the pump on the
intravenous pole relative to the patient. The cannulas exit the patient in
a subcostal manner. The pump is a dual-chamber pump contained in a hard
polycarbonate housing. The upper chamber is a passive, gravity-filled
reservoir and the lower chamber is the pumping chamber. The upper and
lower chamber are separated by an inflow valve and then the lower chamber
is separated from the arterial circulation with an outflow valve that
ensure unidirectional flow of blood. As the pumping chamber is filled with
blood, all of the surrounding air is returned to the console. This is
sensed by the console, which immediately sends compressed air back to the
pumping chamber, compressing the bladder and ejecting blood to the
patient. A
worldwide registry is maintained with the Abiomed BVS 5000. Currently
(1994) 500 patients have been entered into the registry. The majority of
patients were postcardiotomy (53%) and required biventricular assist
devices (65%). Postcardiotomy patients have had a 27% discharge rate
compared with cardiomyopathy patients with a more than 40% discharge rate.
(42). Thoratec From
March 1992 to June 1998, 114 patients received the Thoratec ventricular
assist device : 84 patients in whom the system was applied as a
bridge-to-transplant procedure (68% survived to transplantation with a
posttransplant survival of 88%), 17 patients with postcardiotomy
cardiogenic shock (47% survival) and 13 patients with cardiogenic shock of
other causes (31% survival). Patients are selected for biventricular
support with the Thoratec VAD if one of the following conditions is
present: central venous pressure greater than 20 mmHg and pulmonary artery
pressure – central venous pressure gradient of less than 4 mmHg,
increased pulmonary vascular resistance (>500 dynes./s/cm)., multiple
organ dysfunction, or severe malignant arrhythmias refractory to medical
therapy. The other patients received a Thoratec LVAD or an implantable
LVAD (Novacor or HeartMate provided the body surface area exceeds 1.5 m²).
Duration support was 3 to 184 days. The size of the drive console and the
paracorporeal location of the blood pump make the system unsuitable for
long term support, althought other centers have had successful experience
up to 515 days. Bleeding amounted to 26%, all forms of neurology
complications to 18%. Patient age of more than 60 years turned out to be
the only independent risk factor affecting survival. (43) The
Thoratec VAD system constits of prosthetic ventricules with a 65 l stroke
volume, cannulas for atrial or ventricular inflow and arterial outflow
connections, and a pneumatic drive console. The VADs were placed in a
paracorporeal position on the anterior abdominal wall and were connected
to the heart and great vessels with cannulas crossing the chest wall. Two hundred thirteen transplant candidates who were in imminent risk of dying before donor heart procurement and who received Thoratec left (LVAD) and right (RVAD)ventricular assist devices at 35 hospitals were divided in 3 groups: patients supported with isolated left assist device (n=37), patients initially receiving an LVAD and later requiring an RVAD (37), patients who received a biventricular (BiVAD) assistance from the beginning. In the BiVAD group, the preVAD cardiax index was 1,4 l/min/m²; in the LVAD: 1,6 l/min/m²;wedge pressure: BiVAD :27mmHg, LVAD: 30mmHg; mechanical ventilation: BiVAD: 60%, LVAD: 35%; emergency BiVAD: 22%, LVAD: 9%; survival through heart transplantation: BiVAD: 58%, LVAD: 74%. Hemodynamic measurements were not of much value in separating patients who required univentricular versus biventricular support. The average duration of VAD support was 41 days (longest was 247 days) for the LVAD group compared with 22 days (longest was 236 days) for the BiVAD groups. With the restoration of systemic blood flow, recovery of renal and hepatic function appeared to take 2 to 4 weeks of VAD support in most patients. The earlier the implantation, before significant major organ dysfunction, the more likely that univentricular support will be all that is required, and the greater the likelihood of survival through transplantation. (44) Berlin
Heart Since
1990 small adult-size pulsatile air-driven ventricular assist devices
“Berlin Heart” and since 1992 miniaturized pediatric VAD (12, 15, 25,
30ml pumps) are available. Since 1994 the blood-contacting surface have
been heparin coated. In
28 children – ages between 6 days and 16 years – the Berlin Heart as
been applied for periods of between 12 hours and 98 days aiming at keeping
the patient alive and allowing for recovery from shock sequelae until
later transplantation or myocardial recovery.
Twelve patients died. Thirteen patients were transplanted. Three
patients were weaned from the system. Heart
failure early after cardiac operation is now primarily treated by ECMO.
This mode of treatment has proven successful at our institution, in
particular in infants with myocardial impairment as in Band-White-Garland
syndrome, after switch-operation and total anomalous pulmonary vein
drainage. Acute
myocarditis appears to be a promising precondition for complete cardiac
recovery during VAD support. (45). Heart
mate Sixteen
patients were bridged with the HeartMate left ventricular assiste device
to heart transplantation for NYHA functional class IV cardiac failure. The
main cardiac index and the mean pulmonary vascular resistance were 1.7
l/min/M² and 3 Wood units. Bleeding was the main complication, two
patients suffered from neurologic complications, there were two major
incidents of device malfunction. Twelve patients have received a
transplant, 3 are awaiting a transplant and
in 1 (6%) the device was explanted after spontaneous left
ventricular recovery. Since the start of the LVAD program, 1 patient has
died on the heart transplantation waiting list, compared to nine deaths in
the 2 preceding years (47). From
91 to 96 100 ventricular assist devices were implanted as a bridge to
transplant. Most patients (69%) had ischemic cardiomyoplasty and most
(53%) had previous cardiac surgery. Preoperative ECMO was used in 25.
Perioperative insertion of a right ventricular assist device was unusual
(11%). The mean duration support was 70 (up to 206 days). Survival to
transplantation was 76%. Risk factors for death before transplantation
included preoperative ECMO, ventilator requirement, low pulmonary artery
pressures and elevation of bilirubin, blood urea nitrogen, and creatinine
concentrations. Post operative risks included need for support with a
right ventricular assist device, reoperation for bleeding (21%), dialysis
and device failure. Positive blood culture were detected in 59% of
patients during support. Clinical driveline infection occurs in 28% of
patients. Patients who can leave the hospital and are free to go home and
return in their environnement have a significant improvement in their
quality of life. Cause of death include multiple organ failure (n=13),
perioperative stroke (n=5), device
failure (n=5). Two patients had bridge to recovery. One of them underwent
partial ventriculectomy (Batista procedure). He died from the rapid
return of heart failure.The other is alive. The
device was placed in the abdominal wall pocket, under the posterior rectus
sheath (just above the peritoneum) to minimize contact of the pump with
the raw surface of the posterior part of the rectus muscle and thereby
decrease bleeding from the muscle. Aprotinine was administrated.
Only Aspirin (325 mg/day) was used for LVAD anticoagulation. In
1993, we began to use the vented-electric HeartMate (before: pneumatic)
with a percutaneous line for power.(48). We
studied 25 patients undergoing bridge to transplantation by left VAD;
before LVAD implantation, 94% were supported by IABP and 28% were
supported by ECMO. 16% required RVAD support (we could not identify any
preoperative factors that would indicate that they were at particularly
high risk to need RVAD support..76% received a donor heart and were
discharged. Pretransplantation duration of support averaged 76 days (22 to
153). (49). Novacor Novacor
N 100 and HeartMate are two implantable LVAD approved by the FDA. Between
October 1996 and March 1998, a prospective, single-center study was done
that included 40 patients, 20 of whom were treated with the Novacor system
and 20 of whom were treated with the HeartMate device. There were no
statistically significant differences between the two groups with regard
to postoperative hemodynamics, organ recovery, out of hospital support,
and survival to heart transplantation. Neurologic complications occurred
significantly more often among the Novacor group, whereas the HeartMate
group had a higher prevalence of infections and technical problems.
Bleeding constitutes a problem after VAD implantation. We found a
significantly higher amound of blood loss in the Novacor collective.
Survival to transplantation was 65% for the Novacor group and 60% for the
HeartMate group.(50). In
July 1999, from the European Registry of Novacor (469 patients), 36
patients have lived more than 1 year with the Novacor
wearable electric LVAD. Median duration of LVAS support was 1.49
(1.03-4.10) years. The median time spent outside the hospital was I.27
(0.58-3.83) years, representing 82% of the duration of LVAS support. No
mechanical failure was observed during the entire observation period.
Surgical-related bleeding: 25%, neurological events: 17%. Freedom from
serious systemic infection was 75% at 1 year, 67% at 1.5 year and 58% at 2
years on LVAS. Seven (19%) patients died after a median of 1.24 years
circulatory support. (51). The
Novacor N100PC LVAS consists of a seamless, smooth-surfaced polyurethane
sac bonded to dual, symmetrically opposed pusher plates and to a
lightweight fibreglass/epoxy housing that incorporates the valve fittings.
The inflow and outflow conduits are 25 mm in diameter and contain custom
porcine bioprostheses with sinuses behind each of the valve leaflets. The
inflow conduit is constructed of a low-porosity Dacron graft with a
semi-rigid tip. The outflow conduit is a 25 mm collagen-impregned, woven
Dacron graft. The system controller is located extracorporeally and is
connected to the implanted energy converter via a percutaneous lead, which
also provides a pump vent. The wearable control system provides electrical
energy to a pulsed-solenoid energy converter, which is coupled to the
pusher plates through a flat pring mechanism. The wearable controller
derives power from primary and reserve battery packs when the patient is
ambulating, or an external monitor/power unit that uses standart household
electrical power when the patient is asleep or otherwise minimally active.
The operative technique is described. (52). Thirty-six
patients with a mean age of 50.4 years; 11 died on the device, 23
underwent heart transplantation, 2 still on the device. Causes of death
were mostly related to cerebrovascular events or multiorgan failure. Seven
of the 23 patients who underwent heart transplant died (survival rate
after transplant of 70% and an overall survival rate of 50%. Complications
occurred in 33 patients: 24 strokes, 7 cable infections. Cerebrovascular
complications occurred mostly during the first 3 months of assistance; the
incidence of infections remained constant.(53). In
May 1990, 68 patients have had a Novacor in US. The mean duration of LVAS
support was 40 days. Since 1984, there is an increasing duration of
support which reflects the lengthening wait for donor organs in recent
years. Five were still being supported, 39 had received a transplant
(62%); 34 of them are alive. A short duration of support (less than 6
days) was associated with a poor outcome. An increased period of support
allowed patients to recover more fully. Twenty-four patients had no
reached transplantation status and died. No instances of device failure
have occurred. In
the Stanford University, 13 patients have received this VAD. Seven
patients received prostaglandin early after LVAS insertion, to reduce
right afterload. In addition, all patients received inotropic agents in
the early postoperative period to maximize right ventricule function. With
this regimen, no patient require mechanical right ventricular support.
Ten patients underwent cardiac transplantation (9 alive). Two
patients died of pulmonary fungal sepsis. World
Heart (Heart Saver) First
VAD without connection through the skin (2000: first implantation). ECMO The
system comprises a hollow-fiber membrane oxygenator with heat exchanger, a
centrifugal pump, a oxygen/air blender and a water heater/cooler. All
components are coated with the Carmeda bioactive surface. Cannulation is
via a transthoracic or femoral approach. Between
1992 and 1997, 82 adult cardiac patients were supported on ECMO.
Indications for cardiac assist included postcardiotomy cardiogenic shock (PCCS,
55 patients – 8,300 open heart surgery at the same time - ; survival:
35%, 56% after the 36 isolated coronary bypass), high risk cardiology
intervention (27 patients from whom 85% were discharged), perioperative
cardiac graft failure (4 patients; 50% survival), and emergency cardiac
resuscitation (6 patients; 100% mortality). Thirty-six
% of the patients were discharged from the hospital. Causes of death in
the PCCS population was refractory ventricular failure 574%), severe
neurologic compromise (17%), multiple organ failure (6%), respiratory
failure (3%). Complications in survivors: renal failure (10%), stroke
(10%), transient neurological symptomatology (25%), mediastinitis (10%).
Bleeding was noted in all PCCS ECMO patients. The average number of units
of red cells, fresh frozen plasma and platelets administrated was 29/19/36
units. (55). In
the series of Reichmann, patients with postcardiotomy deterioration,
failed coronary angioplasty, trauma, myocardial infarct, pulmonary
embolism are included for cardiopulmonary support. Seventeen % were
long-term survivors. The
multi-institutional experience reported by Hill summarizes the data of 187
patients who underwent cardiopulmonary support for cardiac arrest (67%),
cardiogenic shock (24%), pulmonary insufficiency (5%), hypothermia (4%).
Of the total population, 21% were alive greater than 30 days. In
survivors, 77% had major therapeutic interventions as compared with 50% of
non-survivors. The
report of Shawl mentions application of CPS in 8 patients with cardiogenic
shock from acute myocardial infarction. Seven patients had successful
angioplasty and were hospital survivors. The
results of ECMO procedures reported to the Extracorporeal Life Support
Organization (ELSO) registry have been published by Bartlett in 1997. From
the almost 14,000 procedures, 73% survived. In the subgroup who underwent
ECMO for cardiac failure (12%), the rate of survival was 41%. The majority
of these patients were pediatric cardiac surgical cases (1,563, 40%
survivors), transplantations (114, 40% survivors), cardiomyopathy (95, 52%
survivors), myocarditis (57, 51% survivors). Hemorragic complications
accounted for about 45% of the patients.(56). Mortality
around 50% to 75% was reported in acute myocarditis (AM) with
abrupt-onset, progressive heart congestive heart failure. Over a 5-year
period, 5 patients with AC were rescue with ECMO. All the patients could
be weaned off the ECMO after 140+57 hours of support. One patient died of
multiple organ failure 10 days after removal ECMO. (57). A
16-month-old-boy suffered a cardiac arrest as a result of acute
myocarditis, and venoarterial extracorporeal membrane oxygenation was
instituted. Twelve hours later, acute left heart distension developed with
cessation of left ventricular ejection. Under transesophageal
echocardiographic guidance, a long introducer was placed into the left
atrium through a transseptal puncture and connected in-line to the
venous circuit. Within hours, left ventricular function improved and
ejection returned. Left heart decompression was continued for 5 days,
and the patient was weaned from extracorporeal membrane oxygenation
after 6 days with normal cardiac and neurological function. (58). Long-term
survival at our institution for postcardiotomy cardiogenic shock patients
supported with the Bio pump is 36% (29/80).
In an effort to improve or results we used heparin-coated ECMO in
21 patients (in the same period, 3.000 open heart operations). Eleven
552%) were discharged to home. After coronary surgery, the survival was
80%; after mitral valve operation: 0% (due to inadequate left ventricular
decompression); after prolonged heart arrest: 0%. The veno-arterial,
heparin –coated ECMO was at full fmow, which resulted in complete
right-heart decompression and minimal pulmonary blood flow. Half of the
patients were extubated an average of 6 days after their original
operation and 4 days after removal of the device. All had bacterial
pneumonia requiring tracheostomy and long-term mechanical support for
approximately 1 month. None of the patient had refractory pulmonary
failure leading to adult respiratory disease syndrome and death. In
a series of important experiments from Edmunds’ laboratory, ECMO was
demonstrated to increase left ventricular systolic wall stress and oxygen
consumption in the postischemic heart. It also increased left ventricular
afterload and resulted in only a small decrease in left ventricular
end-diastolic volume. Thus ECMO actually added to the mechanical burden of
the poorly contracting left ventricule, did not appear to improve
contractility, and did not facilitate functional recovery of the
myocardium.(59).
|
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