TUESDAY MORNING, MAY 7, 1991
7:30 a.m. FORUM SESSION I - Cardiac Surgery
International
Ballroom
F1. Age Dependent Sensitivity to
Unprotected Cardiac Ischemia: The Senescent Myocardium
BRUCE D. MISARE*, IRVIN G. KRUKENKAMP*
and SIDNEY LEVITSKY
Boston, Massachusetts
Septuagenarians and octogenarians are presenting for
complex cardiac surgical procedures in increasing numbers. To adjudicate
whether in-traoperative myocardial management should be optimized for
age-dependant ischemic tolerance, a new model of senile myocardium was
developed in ovine hearts lacking pathological cardiac hypertrophy, dilatation,
or coronary stenosis. Six young, sexually mature and seven elderly (in the last
decile of their captive lifespan) sheep of either sex were used (ages 0.75 +/-
0.11 versus 7.1 +/- 0.45 years, respectively). LV weight to body weight ratios
were not significantly different between age groups (3.09 +/- 0.09 vs. 3.07 +/-
0.19 g/kg, old vs. young, NS). Global left ventricular mechanics were assessed
using intracavitary micromanometery and ultrasonic dimension transducers while
varying preload on right heart bypass both before and 30 min. following 15 min.
of global normothermic ischemia induced by aortic cross-clamping. Contractility
was quantitated by the slope of the linear preload recruitable stroke work
relationship and diastolic mechanics by the slope of the linear end-diastolic
pressure vs. volume relationship. The mechanics data are tabulated:
|
|
|
OLD
|
YOUNG
|
|
|
|
Slope
|
r
|
Slope
|
r
|
|
Systolic
|
Pre
|
48.0
(5.9)
|
.979
|
55.0
(7.2)
|
.974
|
|
|
Post
|
11.6
(4.8)*
|
.720
|
27.7
(5.1)*
|
.970
|
|
Diastolic
|
Pre
|
0.178
(0.029)
|
.859
|
0.228
(0.043)
|
.955
|
|
|
Post
|
0.193
(0.041)
|
.960
|
0.471
(0.069)*
|
.963
|
|
Data: Mean (SEM); Sys:Joules/beat/100gmLV/ml;
Dias:mmHg/ml; *p<0.05 ANOVA
|
Post-ischemic systolic functional injury was
significantly greater in the older group (77.3% +/- 10.7% vs. 45.6% +/- 9.5%
injury, old vs. young, p=0.05). In contrast, diastolic compliance was preserved
in the older hearts (99.4% +/- 4.6% vs. 230% +/- 38% of control, old vs. young,
p=0.05). This report is the first to identify a differential ischemic
sensitivity for senescent myocardium. Future studies should emphasize specific
myoprotective strategies to preserve both systolic and diastolic cardiac
mechanics in the aged heart.
*By Invitation
F2. The Use of Combined
Antegrade-Retrograde Blood Cardioplegia in Pediatric Open-Heart Surgery - The
UCLA Experience
DAVIS C. DRINKWATER, JR. *, CHRIS K. CUSHEN*,
HILLEL LAKS AND GERALD B. BUCKBERG
Los Angeles, California
The benefits
of combined antegrade-retrograde blood cardioplegia are becoming well known in
adult coronary and valvular heart surgery. Many of these advantages relate
directly to the pediatric patient. They include prompt arrest and even
distribution, particularly with aortic insufficiency or open aortic root;
avoiding or limiting ostial cannulation; allowing uninterrupted surgical
procedures; and flushing air/debris from the coronary arteries. We therefore
report on the first 86 pediatric patients at UCLA to receive myocar-dial
protection using antegrade (aortic) infusion in conjunction with retrograde
(coronary sinus) infusion of blood cardioplegia. We employed a retroplegia
catheter with a self-inflating and deflating occlusion balloon on the tip of a
pressure-monitored infusion cannula that remains in the coronary sinus during
the operation. Induction blood cardioplegia, 30 ml/kg in equally divided doses
is administered first antegrade at an aortic pressure < 80 mmHg, followed by
retrograde infusion at < 40 mmHg in the coronary sinus. Maintenance
cardioplegia (15 ml/kg) every 20 minutes is administered through one or both of
the infusion cannula depending on the procedure. Patients' ages ranged from 1
week to 16 years with a mean of 5.5 years. They included the following procedures
in descending order: Fontan (14), VSD (and DORV) closure (13), Rastelli (10),
AV valve repair or replacement (8), tetralogy of Fallot (8), aortic root/Konno
(7), aortic valve repair/replacement (6), coronary reimplantation/fistula
ligation (3), arterial switch (2), and AP window, Senning, Stansel (1 each).
Aortic cross-clamp times ranged from 23 to 219 minutes with a mean of 98
minutes. One early death occurred in a patient with Truncus Arteriosus (1%
30-day mortality). There were no complications related to the catheter. From
this initial positive experience, we conclude that: 1. Combined
antegrade-retrograde blood cardioplegia can be safely used in an expanding
number of pediatric heart operations in all age groups, and 2. Combined
antegrade-retrograde blood cardioplegia may provide additional myocardial
protection in complex congenital heart repairs with excellent patient outcome.
*By Invitation
F3. Electrode-Derived Myocardial pH
Measurements Reflect Intracellular Myocardial Metabolism Assessed by 31p
NMR Spectroscopy During Ischemia
TREVOR C. AXFORD*, JOSEPH A. DEARANI*,
IGOR KHAIT*, W. MICHAEL PARK*,
LEO NEURINGER*, C. ROBERT VALERI*,
MANISHA PATEL*, MHEIR DOURSOUNIAN*
and SHUKRIF. KHURI
Boston and West Roxbury, Massachusetts; Washington,
D.C.
and New York, New York
To study the ability of extravascular myocardial
tissue pH (MpHe) measured with an intramural electrode to reflect myocardial
intracellular metabolic status during ischemia, 14 open-chest dogs had in vivo 31P
NMR spectroscopy during left anterior descending coronary artery (LAD)
occlusion (experimental group, n = 7) or following sham operation (control
group, non-ischemic, n = 7). Spectra were acquired q5min at 4.7 Tesla (256
averages, TR = 1000 msec, pulse width = 30 µsec) with a 2 cm 2-turn RF surface
coil. Intracellular myocardial adenosine triphosphate (ATP) peak area was
normalized to an external phosphate standard (HCCTP). Change in ATP peak area
was expressed as percent of baseline value. During three hours of nor-mothermic
ischemia the observed MpHe correlated with NMR calculated myocardial pH in the
ischemic dogs with an average r value of 0.94, p<0.0001. During this same
interval, the fall in MpHe correlated with the loss of ATP in each dog with an
average r value of 0.91, p<0.0001. Thus, myocardial pH, practically measured
with an intramural electrode, correlates with NMR-derived myocardial pH and
loss of myocyte ATP content and reflects the metabolic status of the myocyte
during ischemia. These data validate the use of extravascular myocardial tissue
pH to assess the adequacy of myocardial preservation during aortic
cross-clamping in cardiac surgery.
*By Invitation
F4. Enhanced Myocardial Protection During
Global Ischemia with 5'-Nucleotidase Inhibitors
STEVEN F. BOLLING*, DOUG C. OLSZANSKI*,
EDWARD L. BOVE, KEITH T. CHILDS*
and KIM P. GALLAGHER *
Ann Arbor, Michigan
Depletion of
ATP precursors, such as myocardial adenosine, during global ischemia results in
poor postischemic ATP repletion and functional recovery. Neonatal hearts are
more resistant to this deleterious effect of ischemia hypothetically, because
they are characterized by low 5'-nucleotidase activity, which may result in
sustained endogenous myocardial adenosine levels during ischemia. Adult hearts,
however, have high levels of 5'-nucleotidase activity leading to depleted
myocardial adenosine levels during ischemia and poor post-ischemic functional
recovery. Augmenting myocardial adenosine exogenously, during ischemia in adult
hearts has a beneficial effect. The present study tests the hypothesis that
preservation of adenosine, better ATP repletion and enhanced post-ischemic
myocardial recovery in adult hearts could be achieved with a "neonatal"
strategy. Therefore, 5'-nucleotidase inhibitors were administered to isolated
perfused adult rabbit hearts subjected to 120 minutes of ischemia (at 34°C) to
determine if this improved functional recovery or nucleotide precursor
availability during ischemia. Hearts received St. Thomas cardioplegia, as
controls (CTL); or cardioplegia containing pen-toxifylline (PENT, 500 mg/l
pentoxifylline); 4-thioinosine (4TI, 2-(p-nitro-phenyl)-4-thioinosine, 20
µmol/1 in DMSO); or DMSO vehicle alone (0.5 ml DMSO/1 cardioplegia). Results
are 45 min after reperfusion. Results are mean ± SD, * = p<.05 vs CTL.
|
|
n
|
%DP
|
%dP/dt
|
dEDP(mmHg)
|
CF(cc/min)
|
%MVO2
|
|
CTL
|
10
|
37 + 8
|
43 + 10
|
19+11
|
38+12
|
51 + 19
|
|
DMSO
|
6
|
40 + 8
|
44 + 7
|
9+11*
|
38+13
|
74 + 6
|
|
4TI
|
8
|
60+10*
|
71 + 16*
|
8 + 5*
|
39 + 7
|
81 + 12*
|
|
PENT
|
8
|
59 + 8*
|
69+10*
|
7 + 5*
|
47 + 8
|
91 + 17*
|
Following ischemia
and reperfusion, recovery of pre-ischemic systolic function (<%DP and
%dP/dt), was significantly better with 5'-nucleotidase inhibition, as was
diastolic function (dEDP) and myocardial oxygen consumption (%MVO2). No changes
in coronary flow (CF) were noted. The data demonstrate that preventing the
catabolism, transport and loss of endogenous adenosine from the heart during
global ischemia, with 5'-nucleotidase inhibitors enhances post-ischemia
functional recovery. We speculate and are persuing that the mechanism is due to
maintenance of intracellular ATP precursor availability.
*By Invitation
F5. Leukocyte-Depleted Controlled
Reperfusion of the Regionally Ischemic Myocardium Reduces Stunning, No-reflow
and Infarct Size
JOHN G. BYRNE*, ROBERT F. APPLEYARD*,
C. CHIN LEE*, GREGORY S. COUPER*,
FRANK G. SCHOLL*, RITA G. LAURENCE*
and LAWRENCE H. COHN
Boston, Massachusetts
Prolonged ventricular dysfunction (stunning)
following emergency coronary grafting for acute regional ischemia carries a
high risk of early mortality. Controlling the initial events of reperfusion has
been advocated as essential for myocardial salvage. Since leukocytes and their
products (oxygen free radicals) are the most important initiating mediators
of reperfusion injury, we tested whether leukocyte-depleted controlled
reperfusion would enhance myocardial salvage in a large animal model of acute
coronary occlusion and surgical reperfusion.
Methods: After baseline measurements and 90 minutes LAD
occlusion, sheep were placed on vented cardiopulmonary bypass (CPB). After 30
minutes cardioplegic arrest, simulating distal anastomoses, the LAD occlusion
was released. Before removing the cross-clamp, controlled reperfusion (SOmmHg,
135ml/min) for the first 20 minutes was delivered at the aortic root with
either unmodified whole blood (control, n = 7) or blood passed through
leukocyte filters (filters, n = 7). The cross clamp was then removed and the
animals weaned from CPB. Mean arterial pressure (MAP), the first derivative of
LV pressure (dP/dt), LV stroke work index (SWI), regional area systolic
shortening (%SS) and regional myocardial blood flow (RMBF) were determined
after 3 hours reperfusion. Percent LV area at risk (Ar) and area of
necrosis (area necrosis/area risk, An/Ar) were determined
at the completion of the experiment.
Results: Filters removed 99% of leukocytes during controlled
reperfusion (p<0.001 vs. control). There were no significant differences in
baseline or end-ischemia (pre-CPB) values for any measurements between groups.
Values after 3 hours reperfusion are expressed as mean ± SEM:
|
|
MAP
mmHg
|
dP/dt
mmHg/sec
|
SWI
ergs/gm(x103)
|
%SS (x10-3)
|
RMBF
ml/min/gm
|
Ar
%LV
|
An/Ar
|
Fillers
|
70 ± 7
|
1868 ± 105
|
35 ± 5*
|
12 ± 12
|
0.57 ± 0.11*
|
20 ± 2
|
40 + 6*
|
|
Control
|
56 ± 8
|
1592 ± 334
|
19 ± 4
|
3 ± 8
|
0.22 ± 0.05
|
19 ± 5
|
70 ± 5
|
|
*:p<0.05 vs. control.
|
Improved left ventricular SWI, increased RMBF and
reduced An/Ar suggest amelioration of myocardial stunning
and the no-reflow phenomenon, and decreased infarct size respectively.
Conclusion: Leukocyte-depleted controlled reperfusion is
superior to whole-blood reperfusion for the surgical treatment of acute
regional ischemia. Treating the initial events of reperfusion should include
methods to prevent leukocyte-mediated reperfusion injury.
*By
Invitation
F6. Donor Heart Valves: Electron
Microscopic and Morphometric Assessment of Cellular Injury Induced by Warm
Ischemia
DONALD G. CRESCENZO*, STEVEN L. HUBERT*,
MARY K. BARRICK*, PHILLIP C. CORCORAN*,
JAMES ST. LOUIS*, ROBERT H. MESSIER*,
ROBERT B. WALLACE and RICHARD A. HOPKINS*
Rockville, Maryland and Washington, D. C.
Cryopreserved allograft valves are being used more
frequently as valvular replacements; use is limited by donor tissue
availability. Leaflet fibroblast viability has been suggested to influence
clinical durability; however, worldwide harvesting protocols currently allow
widely variable warm ischemic times (WITs) ranging from zero to 72 hours. The
WIT (i.e., time from cessation of donor heart beat to initial cooling in tissue
storage solution) is thought to be a critical determinant of cell viability.
Metabolic studies conducted in our laboratory have shown that 2 hours of WIT
depleted ATP reserves and cells converted from aerobic to anaerobic metabolism
to support cell viability, while lactate accumulation continues through 24-36
hours of WIT. The purpose of this study was to apply quantitative morphometric
methods to characterize, by transmission electron microscopy (TEM), valvular
cellular injury resulting from progressive WITs.
Porcine
aortic valve (PAV) tissue was used due to the limited availability of human
allograft valves and justified on the basis of comparable histology to human
aortic valves. The PAVs were harvested and processed with methods currently
used for the cyropreservation of allograft valves. PAVs were harvested with a
spectrum of WITs (40 min., 2, 6, 12, 24 and 36 hours; five valves per WIT; N =
30). Following fixation, each leaflet was cut from the free edge to the base (N
= 90), divided into five aliquots and processed using standard methods. To
ensure randomized tissue selection within each WIT interval, three PAVs and
three tissue blocks per valve were selected randomly and thin-sectioned (54
sections). The first ten cells in each thin-section were photographed and cellular
injury assessed (cell disruption, dilation of en-doplasmic reticulum,
cytoplasmic edema, nuclear and mitochondria! changes). 440 micrographs have
been analyzed using Cochran-Mantel-Haenszel statistics to determine if there
was a significant association between WIT and cellular injury.
The number of cells demonstrating morphologic
evidence of injury at various WITs are as follows: 40 min, 23.2% (21/90); 2
hrs, 30.8% (12/39); 6 hrs, 66.7% (58/87); 12 hrs, 45.3% (43/75); 24 hrs, 79.7%
(63/79); 36 hrs, 72.9% (51/70). The following effect of WIT on cell disruption
was observed: 40 min, 3.3% (3/90); 2 hrs, 2.6% (1/39); 6 hrs, 10.3% (9/87); 12
hrs, 2.7% (2/75); 24 hrs, 10.1% (8/79); 36 hrs, 25.7% (18/70). Our Findings
indicate that there is a significant association between WIT, the extent of
cellular injury (WIT 24 hours; p<0.001) and cell disruption (WIT 36 hours;
p<0.0001). These data represent the first ultrastructural (TEM) morphometric
evaluation of the effects of WIT in a model analogous to human donor tissue
harvesting. Our findings indicate that current allograft harvesting practices
with very restrictive WIT allowances result in minimal fibroblast injury;
however, these protocols may be overly restrictive leading to the loss of
potentially usable tissue.
*By
Invitation
F7. Growth of Composite Conduits Utilizing
Longitudinal Arterial Autograft
KAZUO SAWATARI*, HIROAKI KAWATA*,
LOIS C. ARMIGER* and RICHARD A. JONAS
Boston, Massachusetts and Auckland, New Zealand
Many
reconstructive procedures for congenital heart disease, particularly those
requiring conduit insertion, would be more corrective than palliative if they
were to incorporate growth potential. We have confirmed the growth potential of
a longitudinal strip of autologous aortic wall incorporated in an autologous
pericardial conduit in 10 lambs (mean age 26 days). A 15 mm length of
descending thoracic aorta (diameter 11.5 ± .7 mm) was excised and replaced with
a composite autograft conduit of autologous pericardium with a longitudinally
inserted aortic strip 5 mm in width taken from the excised aortic tissue.
Radiopaque markers along all suture lines allowed determination of growth of
the aortic autograft relative to growth of entire conduit in addition to growth
assessment by pathological analysis. Plain x-rays and aor-tograms were
performed at baseline and at 3, 6, 9 and 12 months. No graft became stenotic or
aneursymal. Appropriate growth was demonstrated by minimal change in diameter
ratio of conduit to distal aorta from 1.00 to 1.02 over 12 months. Aortic
strips showed 172 ± 19%, 148 ± 15% and 256 ± 31% incrases in width, length and
area, respectively. Histological study confirmed maintenance of normal
architecture in the aortic strip. There was in-timal and medial proliferation
colonizing the pericardial tissue. A clinical implant using an autologous
aortic strip in an aortic homograft in a 4-year old with tetralogy and
pulmonary atresia has also demonstrated growth from 15 mm to 21 mm diameter at
one year follow-up angiography.
This study confirms that incorporation of autologous
arterial wall into cardiac reconstructive procedure allows for subsequent
growth. The experimental study also demonstrates the safety of autologous
pericardium for aortic reconstruction in the neonatal lamb.
*By Invitation
F8. An Aortic Valve Sparing Operation for
Patients with Aortic Incompetence and Aneurysm of the Ascending Aorta
TIRONE E. DAVID and CHRISTOPHER M. FEINDEL*
Toronto, Ontario, Canada
A number of patients (pts) with aortic incompetence
(AI) and ascending aorta (AA) aneurysm have normal aortic valve (AV) leaflets.
The AI is caused by annular distorsion and or dilatation. We have repaired the
AV and replaced the AA in these pts employing the following technique. All
three aortic sinuses were excised, leaving only 0.5 cm of aortic tissue
attached to the annulus. Interrupted horizontal mattress sutures (4-0
polyester) were passed from inside to outside of the aortic root at a plane
corresponding to the lowest level of the annulus. These sutures were then passed
through one end of a collagen impregnated tubular Dacron graft in such a way to
correct the annular dilatation. The diameter of the graft was 1.4 times greater
than the distance from the base to the free margin of the smallest AV leaflet.
The native AV was placed inside the graft and all sutures tied down. The AV
commissures were resuspended and secured to the graft with a continuous suture
(4-0 polypropylene) similarly to what is done when an AV homograft is
implanted. Both coronary arteries were re-implanted and the graft was
anastomosed to the distal AA.
This operation has been successfully performed in 8
pts; 5 women and 3 men whose mean age was 43 years, range 21 to 63. Three pts
had Marfan's syndrome and 2 had acute aortic dissection. The AI was severe in 6
pts and moderate in 2. There were no operative deaths nor serious postoperative
complications. These pts have been followed from 2 to 21 months, mean of 7.
Serial Doppler echocardiographic studies indicated that the AV reconstruction
remained stable in all pts. Seven had no AI and one had mild AI. No
anticoagulants were given and there has been no thromboembolic complication.
This
operation provides excellent functional results in pts with AI and AA aneurysm
with normal AV, and it may be preferable to composite replacement of the AV and
AA with a prosthetic valve.
*By Invitation
F9. CABG Morbidity Decreased by EEC
Monitoring
A. DAVID SLATER*, LYNN K. GRIFFITHS*,
JACOBA VAN DER LAKEN*, CHRISTOPHER B. SHIELDS*
and HARVEY L. EDMONDS, JR. *
Louisville, Kentucky
Sponsored by: Laman A. Gray, Jr., Louisville,
Kentucky
We have previously demonstrated that persistent
increases in slow wave EEC activity occurring during cardiopulmonary bypass
predicted signs of postoperative neurologic dysfunction (PND). Without
adjustment of surgical/anesthetic technique, PND was observed in 14/48
myocardial revascularization procedures. The current findings describe the
effect of increasing cerebral perfusion in response to intraoperative EEG
evidence of ischemia.
METHODS: In 30 consecutive patients with coronary artery
bypass, the EEG was obtained from 8 bipolar electrode pairs fixed in standard
positions. The EEG, ECG, and mean arterial pressure signals were amplified,
digitalized, displayed, and stored using a signal analyzer (Cadwell Labs,
Kennewick, WA). Ischemic events were identified by a 5 min 3 standard deviation
increase in relative (% total) delta (1.5-3.5 Hz) EEG power referred to
individualized reference norms established prior to insertion of the perfusion cannulae.
Ischemic changes most often occurred during rewarming, and attempts were made
to increase cerebral perfusion mechanically or pharmacologically.
RESULTS: Intraoperative ischemic events were detected in 9 of
30 surgeries. Increased perfusion promptly corrected the EEG abnormality in 6
cases. There was no evidence of PND in any of these 6 patients. Signs of PND
appeared in only 3 patients, 2 of whom displayed ischemic EEG changes
intraoperatively. PND in the third patient appeared to be unrelated to a specific
intraoperative event.
DISCUSSION: Prior to interventional monitoring, our rate of PND
following myocardial revascularization was 29%. By prompt identification of
early cerebral ischemia and intervention, the PND rate has decreased
significantly to 10% (P<0.05, Chi23.98).
Computerized
EEC-based intervention decreased the incidence of PND.
*By Invitation
F10. Poloxamer 188 Improves Neurological
Outcome Following Hypothermic Circulatory Arrest
CRAIG K. MEZROW*, MAURIZIO MAZZONI*,
DAVID WOLFE*, HOWARD H. SHIANG*,
ROBERT LITWAK and RANDALL B. GRIEPP
New York. New York
Poloxamer 188, a hydrophilic and hydrophobic
copolymer possesses favorable cytoprotective and rheologic properties. We
investigated the possibility of improving neurologic outcome with this agent
following prolonged periods (150 min.) of hypothermic circulatory arrest (HCA).
PROTOCOL: Thirteen mongrel dogs (20-25 kg) anesthetized with
Na pen-tobarbital were cooled to 10 C with combined surface/cardiopulmonary
bypass (CPB), arrested for 150 minutes, rewarmed and weaned from CPB. Seven
dogs were treated with poloxamer 188 before and following HCA. Six control dogs
were saline treated. The Dogs were evaluated (blinded fashion) and observed
daily (one week) following HCA for clinically overt neurologic deficits and/or
behavioral changes. Neurologic outcome was graded with the following system:
Gade I - death within the observation period; Grade II -comatose; Grade III -
holds head up; Grade IV - sits up; Grade V - stands; Grade VI - normal in both
behavior and gait.
RESULTS: There were no deaths in the Poloxamer 188 treated animals and they
manifested significantly less neurologic dysfunction following HCA compared to
the control group (p<0.02) (Fig. 1).
This study documents that Poloxamer 188 has a
significant impact in improving neurological outcome in exceptionally long
periods of HCA.
*By Invitation
TUESDAY MORNING, May 7, 1991
9:00 a.m. SCIENTIFIC SESSIONS -
International Ballroom
12. Quality of Life After Myocardial
Revascularization: Effect of Increasing Age
JOSEPH S. CAREY and RAMON A. CUKINGNAN
Torrance, California
Older patients are being referred for coronary
artery bypass surgery (CAB). We studied the effect of increasing age on quality
of life (QL), probability of survival (PS) and risk of reoperation (RR) in 2479
patients followed prospectively 1-20 years. QL was determined from annual
questionnaires, calculating the health status index (HSI) from the patients'
subjective response to surgery: asymptomatic, "greatly improved," HSI = 1.0;
mild symptoms, "greatly improved," 0.8; moderate symptoms, "slightly improved,"
0.6; "not improved" or "worse," 0.4. Four age groups were studied: = <49
(AG40), 50-59 (AG50), 60-69 (AG60), and = >70 (AG70). Associated problems
(LV aneurysm, valve disease, acute myocardial infarction) requiring treatment
were present in 17% (61/361) of AG40, 19% (164/858) of AG50, 23% (213/927) of
AG60 and 31% (104/333) of AG70 patients. Hospital mortality (HM) for all
patients was 6.9% (AG40), 3.7% (AG50), 6.3% (AG60) and 9.9% (AG70). HM in
patients undergoing CAB grafts only with EF > .40 was 2.7% (AG40), 1.8%
(AG50), 3.1% (AG60) and 4.2% (AG70).
PS and RR were calculated by the Kaplan-Meier method
excluding valve and cardiogenic shock patients. PS at 5, 10 and 15 years was
.85, .70, .55 (AG40); .87, .68, .54 (AG50); .81, .63, .43 (AG60) and .70, .50,
.32 (AG70). RR at 15 years was 27% (AG40), 17% (AG50), 6% (AG60) and 8% (AG70).
QL was determined by averaging the mean yearly HSI. For years 1-5, QL was .85
in AG40, .84 in AG50, .89 in AG60 and .90 in AG70. For years 6-10, QL was .81,
.80, .86 and .89 respectively.
This study
shows that in AG40 and AG50 patients, reoperation rate is high and QL is lower
as compared to older patients, reflecting the influence of active coronary
atherosclerosis. After age 60, the risk of reoperation drops off significantly
and symptomatic relief is maintained, suggesting that the probability of
recurrent atherosclerosis is diminished. Therefore, despite a somewhat higher
early risk of mortality, myocardial revascularization is likely to be of
lasting benefit to older patients, supporting the rationale of coronary bypass
grafting in this group.
*By Invitation
13. Operative Mortality is Less for
Unstable Angina Patients Undergoing Coronary Bypass Surgery Early than Late
RAM SHARMA*, ROBERT H. DEUPREE*,
ELLIOTT SCHECTER*, SHUKRI F. KHURI,
ROBERT J. LUCHI* and STEWART M. SCOTT
West Roxbury, Massachusetts, West Haven,
Connecticut, Oklahoma City, Oklahoma, Houston, Texas
and
Asheville, North Carolina
We conducted
a VA multicenter prospective, randomized trial designed to compare medical (M)
and early surgical therapy (S, within 7 days of randomization) in 468 patients
(pts) with unstable angina (UA). Two hundred and thirty-seven pts were assigned
to M and 231 to S. Of the 237 medical patients 79 patients had to be crossed
over to S within the first two years because of failure of M. Of the 231 pts
randomized to S, 207 received early surgery, 13 received surgery more than 30
days after randomization, and 11 were never operated upon; Operative mortality
(i.e. mortality up to 30 days) in the 207 pts who received early surgery was
compared to that in the 79 pts who failed M and crossed over to S (late).
|
|
OPERATIVE MORTALITY
|
|
|
|
Early S
|
Late S
|
p Value
|
|
All UA PTS
|
|
9/207 (4.3%)
|
8/79 (10.1%)
|
0.06
|
|
c EF
|
|
1/69 (1.5%)
|
3/26 (11.5%)
|
0.02
|
|
c 3-Vessel
Disease & EF
|
}
|
0/35 (0%)
|
2/14 (14.3%)
|
0.03
|
Conclusion:
Coronary
bypass surgery in unstable angina pts should be performed early; delaying
surgery increases operative mortality, particularly in pts with reduced
ejection fraction.
*By Invitation
14. Ventricular Assist Devices for
Postcardiotomy Cardiogenic Shock: A Combined Registry Experience
WALTER E. PAE, JR., CYNTHIA A. MILLER*
and WILLIAM S. PIERCE
Hershey, Pennsylvania
Despite advances in myocardial preservation and
cardiac surgical techniques, PCCS remains a significant cause of death. VADs
have been employed failing conventional therapy to diminish myocardial work
allowing time for metabolic recovery of the stunned' myocardium. Since its
inception in 1985, the Combined Registry for the Clinical Use of Mechanical
Ventricular Assist Devices, investigators have voluntarily submitted data on
patients (nts) receiving VADs for PCCS:
|
|
Left VAD
|
Right VAD
|
Bi-VAD
|
TOTAL
|
|
Number
Pts
|
454
|
107
|
283
|
844
|
|
Weaned
(WN)
|
227
(50.0%)
|
43
(40.2%)
|
101
(35.7%)
|
371
(43.9%)
|
|
Discharged
(DC)
|
122
(26.9%)
|
27
(25.2%)
|
48
(17.0%)
|
197
(23.3%)
|
In the
rare instances of device dependency and no contraindications to transplant, 43
pts underwent "bridge" to cardiac transplant. Of these, 35 pts (81.4%) were
transplanted and 20 (46.5%) survived. Coronary artery bypass grafting was the
most prevalent original operation. Regardless of the surgical procedure or the
type (centrifugal vs. pneumatic) of device used for support, the percent of pts
WN and eventually DC was similar. Pts were supported with an mean duration of 3
to 5 days; those pts that were WN but not DC were supported for a significantly
longer period of time. There is a linear relationship that as age increases,
the probability of being WN and DC decreases, with the lowest rate of DC being
10.6% for pts over 70. Multivariate analysis of complications in pts supported
with VAD's indicate: 1) inadequate cardiac output post VAD insertion, 2) pre
VAD biventricular failure and 3) infection impact negatively on the ability to
WN a pt. Similarly, if a pt is WN, renal failure impacted negatively on DC. Two
year actuarial survival for DC pts was 92% for left VAD support, 88% for right
VAD support and 94% for biventricular support. This multi-institional
experience would continue to support the use of VAD in PCCS.
10:00 a.m. INTERMISSION - VISIT EXHIBITS
*By Invitation
10:45 a.m. SCIENTIFIC SESSIONS - International
Ballroom
15. Applicability of Noncardioplegic
Coronary Bypass to High Risk Patients
LAWRENCE I. BONCHEK, MARK W. BURLINGAME*,
BRAD E. VAZALES* and EDWARD F. LUNDY*
Lancaster, Pennsylvania
Although some
surgeons still prefer noncardioplegic (NCP) coronary bypass (CAB), most surgeons
are skeptical of its suitability for high risk patients. We used multivariate
discriminant analysis to assess risk factors and results in the first 3000 pts.
who had primary CAB without cardioplegia (CP) since our program's inception in
1983. Most grafts were done with intermittent aortic clamping, but local vessel
control was often used without clamping. Average number of grafts was 3.5/pt.
Pts. with reoperations or valve operations were excluded. Multivariate
predictors of operative death included age, sex, LV dysfunction, preop
intraaortic IABP, and urgency of operation. Many pts. were in these high risk
subgroups. 879 pts. (29%) were > 70 yrs. old; 346 (11.5%) had EF < .30
and another 77 (2.56%) had LV aneurysms; 196 (6.5%) had acute MI and another
397 (13%) had MI < 1 week preop; 917 (31%) had rest pain in hospital
(preinfarction angina). Only 790 (26%) had elective operations.
Overall operative mortality was 1.3% (39/3000):
elective 0.5% (4/790); urgent 1.4% (24/1687); emergency 2.1% (11/523). In pts.
with EF < 30% mortality was 4.6% (16/346); with age > 70 it was 3.4%
(30/879); with acute MI it was 3.1% (6/196); and with LV aneurysmectomy it was
0% (0/77). Only 6.6% (199 pts.) required inotropic support after leaving the
operating room and only 1% (30 pts.) required a new IABP postop (only 2 of
these 30 died).
Noncardioplegic technique has several advantages.
Complexity of equipment, cost, and operating time are reduced. Familiarity with
NCP techniques facilitates CAB in the growing number of pts. with aortic
calcification that precludes crossclamping and CP. IMA use is simplified in
acute coronary occlusion. These results provide reassurance that
noncardioplegic CAB provides excellent myocardial protection and operating
conditions for primary CAB, and is particularly suitable for high risk pts.
*By Invitation
16. Incremental Risk of Bypass Surgery for
Patients with Left Ventricular Ejection Fractions Less than 20%
GEORGE T. CHRISTAKIS*, STEPHEN E. FREMES*,
RICHARD D. WEISEL, JOAN IVANOV*,
TIRONE E. DAVID and TOMAS A. SALERNO
Toronto,
Ontario, Canada
Patients undergoing aortocoronary bypass surgery with
severe ventricular impairment [left ventricular ejection fraction (LVEF)
<20%] are at high risk of operative mortality. The incremental risk factors
for mortality in patients with LVEF <20%, and the mechanisms by which they
contribute to mortality are not well understood. Between January 1982 and June
1989, 11,177 patients underwent isolated aortocoronary bypass surgery. Forty
perioperative variables were collected prospectively and analyzed by
multivariate statistical techniques. 8,640 patients had preoperative LVEF
>40% with an operative mortality of 2.3%. 2,286 patients had preoperative
LVEF between 20 - 39% with an operative mortality of 5.1% and 431 patients had
preoperative LVEF <20% with an operative mortality of 9.1%. Patients
undergoing coronary bypass surgery with LVEF <20% had a higher incidence of
left main stenosis (25%), preoperative intraaortic balloon pump (15%), and
underwent urgent surgery for unstable angina more frequently. Stepwise logistic
regression analysis revealed that urgent surgery for unstable angina was the
only independent risk factor for mortality. Traditional risk factors including
redo surgery, age, sex and left main stenosis did not contribute to the
operative mortality in this highly selected group of patients with severe
ventricular dysfunction. Patients undergoing elective surgery for stable angina
with LVEF <20% had a 5% operative mortality. Patients undergoing semi-elective
surgery had an 8% operative mortality while the operative mortality increased
to 25% for patients undergoing urgent surgery for unstable angina.
CONCLUSION: The major independent predictor of operative
mortality for patients with preoperative left ventricular ejection fractions
<20% is urgent surgery for unstable angina. Traditional risk factors for
CABG contribute minimally to operative mortality in patients with poor
ventricular function. Unstable patients with severe ventricular impairment face
a high mortality and medical stabilization should be attempted prior to
surgery. Perhaps, modified techniques of myocardial preservation designed to
resuscitate the injured heart, should be assessed in this high risk sub-group.
11:30 p.m. ADDRESS BY HONORED SPEAKER
Long-Term Transplantation as a
Model
Magdi
Yacoub, M.D., London, England
12:15 p.m. CARDIOTHORACIC RESIDENTS' LUNCHEON
Jefferson Room (Tickets
Required)
*By Invitation
