1:30 p.m. SCIENTIFIC SESSION - Dominion
Ballroom
33. Efficacy of Dynamic Cardiomyoplasty in Dilated
Cardiomyopathy
K. FRANCIS LEE*,
REBECCA J. DIGNAN*,
CORNELIUS L. DYKE*,
JITENDRA M. PARMAR*,
THOMAS YEH, JR*,
GARY BENTON*. ANWAR S. ABD-ELFATTAH*
and ANDREW S.
WECHSLER
Richmond, Virginia
Although dynamic Cardiomyoplasty (CMP) has
entered the phase of active clinical trials, its direct effects on the failing
heart have not been thoroughly documented. The deterioration in congestive
heart failure is associated with progressive enlargement of the left
ventricular chamber, decrease in cardiac output, and increased work load on the
heart. We tested the hypothesis that dynamic Cardiomyoplasty may produce
beneficial changes in the functional mechanics of the dilated, failing left
ventricle (LV).
A model of chronic dilated Cardiomyopathy was
induced in seven mongrel dogs by rapid ventricular pacing (260 b.p.m.) for
three to four weeks. After the induction period, dynamic Cardiomyoplasty was
performed with left latissimus dorsi, which was paced synchronously with the
R-waves of the EKG (Medtronics SP1005). Instrumentation included an aortic flow
probe, a LV Millar pressure catheter and piezoelectric ultrasonic crystals on
the LV for measurements of wall thickness, minor axis, and major axis
dimensions. Data were obtained during control (CMP-OFF) vs. study conditions
(CMP-ON). Differences were analyzed with paired t-tests.
|
|
Cardiac
|
LV Pressure (mmHg, mmHg,
mmHg/Sec)
|
LV Wall Thickness (mm)
|
|
|
Output
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|
|
|
|
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CMP
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(ml/min.)
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Peak Sys
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Dias
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Peak dP/dt
|
Dias
|
Sys
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Thick'ng
|
|
OFF
|
966 ± 124
|
94 ± 4
|
18 ± 1
|
867 ± 38
|
10.1 ± 1.2
|
11.8 + 1.1
|
1.7 ± 0.2
|
|
ON
|
1166 ± 112
|
104 ± 4
|
15 ± 1
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1254 ± 96
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10.4 ± 1.1
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12.7 ± 1.1
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2.3 ± 0.2
|
|
P =
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< 0.01
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<0.01
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<0.01
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<0.01
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N.S.
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<0.01
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<0.01
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|
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Minor Axis Dimension (mm)
|
Major Axis Dimension (mm)
|
|
|
CMP
|
Dias
|
Sys
|
Short'ng
|
Dias
|
Sys
|
Short ng
|
|
|
OFF
|
54.3 ± 1.6
|
51.3 ± 1.4
|
3.1 ± 0.3
|
90.2 ± 3.5
|
85.6 ± 3.3
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4.6 ± 0.3
|
|
|
ON
|
53.9 ± 1.7
|
49.2 ± 1.8
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4.7 ± 0.3
|
86.3 ± 2.8
|
7.9 ± 2.3
|
7.3 ± 0.9
|
|
|
P =
|
N.S.
|
<0.01
|
<0.01
|
<0.05
|
<0.05
|
<0.05
|
|
|
|
|
|
|
|
|
|
|
|
|
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[All values are
represented as means ± S.E.M. PEAK SYS, peak systole; SYS, end-systole; DIAS,
end-diastole; SHORT'NG, shortening; THICK'NG, thickening. Statistical analysis
is by paired t-test. N.S., not significant.]
Dynamic CMP increased the forward output of
the failing heart. Systolic shortening of both minor axis and major axis
dimensions were increased. Improved emptying of the congested left ventricle
was associated with beneficial changes in the loading conditions of the dilated
LV. Preload, as determined by LV end-diastolic pressure, decreased by 16% (p
< 0.05). Although skeletal muscle contraction increased the pressure
development in the LV chamber, wall stress was diminished by concomittant
changes in the LV dimensions. Systolic wall thickness increased by 8% (p <
0.01); minor axis dimension decreased by 2% (p < 0.01); and major axis
dimension decreased by 8% (p < 0.05). Our detailed evaluation of LV chamber
mechanics suggest that dynamic cardiomyoplasty may have a role in ameliorating
the functional and mechanical derangements associated with progression of
dilated car-diomyopathy both by augmenting cardiac performance and by
diminishing determinants of myocardial oxygen consumption.
*By Invitation
34. Left Ventricular Function Changes After Cardiomyoplasty
in Patients With Dilated Cardiomyopathy
ADIB D. JATENE,
NOEDIR A.G. STOLF*,
LUIZ F.P. MOREIRA*,
EDIMAR A. BOCCHI*,
PAULO M.P. FERNANDES* and PEDRO SEFERIAN*
São Paulo, Brazil
Stimulated skeletal muscle flaps, contracting
synchronously with the heart, have been proposed to reinforce or partially
replace the ventricular walls in the treatment of irreversible myocardial
failure. Between May 1988 to September 1989, latissimus dorsi Cardiomyoplasty
was performed in 11 patients with dilated cardiomyopathy who were in N.Y.H.A.
class III or IV despite maximal medical therapy. Mean cardiothoracic index was
58 ± 2%, resting left ventricular ejection fraction (Thechnetium 99m
scintigraphy) ranged from 15 to 28% and mean cardiac index (thermodilution) was
1.78 ± 0.25 lit./min. m2.
The reinforcement technique was realized
without cardiopulmonary bypass and using two different incisions to muscle
dissection and to cardiac access. There were no operative deaths and the
prophylactic use of sym-pathomimetic amines and vasodilators provided an
adequate hemodynamic condition during the surgical procedure and in the
immediate postoperative period. Loss of muscle flap contraction occurred in 1
patient due to latissimus dorsi ischemia and this patient died two months after
the operation in congestive heart failure. The other 10 patients followed a
progressive muscle stimulation protocol for a period of three months.
Two patients remain in the course of muscle
conditioning period and 8 patients were followed from 4 to 18 months with an
average of 10.2 months. Four of these patients are in N.Y.H.A. class I, 3 in
class II and 1 in class III. Echocardiographic evaluation showed that left
ventricular (LV) segmental wall shortening increased from 11.5 ± 2.8 to 17 ±
3.9% (p<0.01) at the 3rd postoperative month and was maintained at the same
levels 6 months after the operation. Similarly, Technetium 99m scintigraphy
documented a LV ejection fraction improvement of 31 ± 14% (p<0.04) after the
muscle conditioning period. Significant increments of LV stroke index were
determined by Doppler-echocardiography and by thermodilution 3 and 6 months
after Cardiomyoplasty. Values of mean pulmonary wedge pressure of 24 ± 4.2,
18.1 ± 6.5 and 17.5 ± 6.9 mmHg and LV stroke work indexes of 14 ±3.5, 23.1 ±7.5
and 21.5 ±6.8 gm.m/m2 were documented by cardiac catheteriza-tion at
the preoperative evaluation and at the 3rd and 6th postoperative months,
respectively. In addition, the three patients who had a left ventricular end
diastolic diameter greater than 80mm presented a less evident variation of the
left ventricular function and the presence of moderate mitral regurgitation
represented also a limitation for a better hemodynamic performance in another
patient.
In conclusion, cardiomyoplasty may be
performed with acceptable immediate mortality and may improve left ventricular
function in patients with dilated cardiomyopathy, providing a better control of
congestive heart failure state. However, the benefits of this new surgical
technique seems to be less important in patients with greater left ventricular
compromise.
*By Invitation
35. Clinical Experience With the Novacor
Ventricular Assist System
PATRICK M.
MCCARTHY*, PEER M. PORTMER*,
VAUGHN A. STARNES*,
H. GARETH TOBLER*,
NARA YANAN RAMASAMY*
and PHILIP E. OYER
Stanford and
Oakland, California
At our institution, 12 patients (pts) had a
Novacor electrical left ventricular assist system (LVAS) placed as a bridge to
heart transplant (Tx) before 10/89. During the pre-LVAS hospitalization (mean 13
days), all pts were receiving inotropic support for biventricular failure (4
were also on the IABP), 10 had pulmonary edema (6 required intubation), 6
developed ventricular arrhythmias (4 had cardiac arrest), 5 had liver
dysfunction with coagulopathy, and 2 had renal failure requiring artificial
support. The mean cardiac index (C.I.) before LVAS was 1.52. All LVAS survivors
had a dramatic increase in cardiac output (mean C.I. = 3.07). In addition, the
mean PA diastolic pressure decreased from 26.4 ± 9.1 mmHg pre-implant to
17.3 ± 8.1 mmHg 24 hours post LVAS (p<0.005). One pt with cardiac allograft
rejection died at LVAS implantation from akinesis of the right ventricle. Two
pts died of pulmonary sepsis 16 and 21 days post LVAS implantation. Five pts were
able to ambulate in the hospital and ride stationary bicycles while awaiting
transplantation. Nine patients (75%) were successfully transplanted after a
mean of 16 (range 2 to 34) days on the LVAS. One patient died two days after Tx
of presumed sepsis. Eight pts (89%) are alive one month to five years post Tx.
In the United States, 53 pts (as of 10/89)
have had a Novacor LVAS implanted. Three patients are still supported, 30 were
transplanted (60%), and 26 pts (87%) survived the transplant hospitalization (one
died late). No instances of device failure have occurred. In conclusion, the
Novacor LVAS provided effective bridging to Tx, with post Tx survival similar
to results after routine Tx. The bridge to Tx experience has provided a preview
of future applications of the device. Many of these critically ill patients
recovered sufficiently to allow the early resumption of normal activities.
Isolated left heart support with a fully implantable LVAS will be offered as an
alternative to heart Tx for selected pts in the 1990's.
*By Invitation
36. Discriminate Use of Electrocautery on the
Median Sternotomy: 0.16% Wound Infection
HIROSHINISHIDA*,
RONALD K. GROOTERS*,
WON-PA KIM*,
HOOSHANG SOLTANZADEH*,
KENT C. THIEMAN* and
ROBERT F. SCHNEIDER*
Des Moines, Iowa
Sponsored by: Ralph
A. Dorner, Des Moines, Iowa
Between June, 1978, and June, 1989,
superficial infection and/or deep mediastinitis developed in only 5 (0.16%) of
3,118 consecutive patients. All patients studied underwent open heart
procedures through a median ster-notomy and survived more than seven
postoperative days. The surgical team disciplined itself to divide presternal
soft tissues with a scalpel, and used elec-trocautery only for pinpoint
hemostasis to preserve tissue viability. This 0.16% incidence was statistically
significantly lower than 28 previously published studies (Pearson's chi-square
test, p<0.05). Twenty-five predisposing factors were evaluated by Fisher's
exact test: age, sex, obesity, diabetes mellitus, smoking, chronic obstructive
pulmonary disease, renal failure, malignant disease, steroid usage, the length
of hospitalization before surgery, preoperative New York Heart Association
classification, left ventricular end-diastolic pressure, ejection fraction,
operative procedure, internal mammary artery usage, emergency operation,
reoperation, duration of cardiopulmonary bypass, operating time,
re-exploration, intraaortic balloon pumping, inotropic agents, perioperative
myocardial infarction, stroke, and prophylactic antibiotics. Among these only
the operating time longer than 3 hours is related to Sternotomy infections (p =
0.02). Statistical evidence strongly suggests that discriminate use of
electrocautery minimized infection risk factors and has produced the lowest
reported Sternotomy infection rate to date.
*By Invitation
37. Preservation of the Aortic Valve and Aortic
Root in Ascending Aortic Dissection
JAMES I. FANN*,
DONALD D. GLOWER*,
J. SCOTT RANKIN,
NORMAN E. SHUMWAY,
WALTER G. WOLFE and
D. CRAIG MILLER
Stanford, California and Durham, North Carolina
Surgery is the optimal approach to treatment
of ascending aortic dissection; however, indications for concomitant
replacement of the aortic valve and/or root remain to be defined fully. The
operative approach and outcome of 282 patients admitted to two institutions
with type A (ascending) aortic dissection were assessed. A total of 195 (69%)
patients presented with acute and 87 (31%) with chronic type A dissections.
Follow-up was complete in 98% of patients and extended to 20 years (mean 4
years). One hundred and twenty-four (44%) patients underwent aortic valve
procedures: 49 (41 acute and 8 chronic) had aortic valve resuspension with an
operative mortality of 10% (5/49); 75 (38 acute and 37 chronic) underwent
aortic valve replacement (AYR) with an operative mortality of 21% (16/75) (p =
0.14 vs. resuspension); 16 (8 acute and 8 chronic) of these AYR patients
had concomitant aortic root replacement (operative mortality of 6% [1/16]). The
indications for valve replacement generally included underlying (non-acute)
aortic valve disease, Marfan's syndrome, and annuloaortic ectasia. Only 2 of 49
patients who initially underwent valve resuspension required late AYR at 72 and
77 months (freedom from late AYR: 100% and 80% at 5 and 10 years). Four
patients (4/75) who underwent initial AYR later required re-do AYR at 27, 81,
101, and 106 months (freedom from late re-do AYR: 98% and 70% at 5 and 10
years). Two patients (2/16) with AYR and aortic root replacement required
subsequent root replacement at 48 and 71 months (freedom from late aortic root
replacement: 100% and 83% at 5 and 10 years). Overall late survival rates for
patients with initial AYR were 68%, 40%, and 16% at 5, 10, and 15 years,
respectively. Overall late survival rates for patients with resuspension were
65% and 42%, and 21% at 5, 10, and 15 years, respectively (p = 0.5 vs.AYR).
Multivariate Cox model analysis revealed that advanced age (p = 0.0001),
previous cardiac or aortic operation (p = 0.0003), more preoperative
complications (p = 0.0005), and earlier operative date (p = 0.006) were
significant independent risk factors for late death. Preservation of the aortic
valve or aortic root at initial operation was not associated with increased
risk of late death or late replacement of aortic valve or aortic root. Conclusion:
A conservative surgical approach to patients with type A aortic dissections
favoring preservation of the native aortic valve and aortic root yields
satisfactory long-term results; therefore, attempts should be made to resuspend
the valve and preserve the root, whenever possible, in patients with aortic
regurgitation and type A dissection.
*By Invitation
38. Effect of Right Atrial Appendectomy on the
Release of Atrial Natriuretic Hormone
BASSAM O. OMARI*. RONALD J. NELSON
and JOHN M.
ROBERTSON*
Torrance and Los
Angeles, California
Atrial Natriuretic Hormone (ANH) is released
from the right atrial appendage in response to atrial distension. During open
heart surgery the right atrial appendage is usually partially removed or
ligated for venous cannulation.
To evaluate the effect of right atrial
appendectomy on the release of ANH and its natriuretic and diuretic responses
we prospectively randomized 23 patients undergoing elective coronary artery
bypass surgery into two groups. There were 16 males and 7 females with a mean
age of 62 ± 7 years. Group A (n = 11) had their right atrial appendage removed
and Group B (n = 12) had their right atrial appendage preserved and venous
cannulation was done lateral to the appendage. Both groups were comparable for
sexual distribution, age, number of grafts, and extracorporeal bypass time. All
patients had normal left ventricular and renal functions, and they did not
receive any diuretics during the study period.
The patients were studied both preoperatively
and postoperatively whereby the ANH serum levels, urine volume/min (V),
fractional excretion of sodium (FENa), amount of sodium excreted (UNaV) and
central venous pressure (CVP) were measured before and after volume expansion
with 7.5 cc/kg of 5% albumin. There was no statistical difference in these
parameters preoperatively. However, in the postoperative period Group B
patients had higher ANH levels after volume expansion that Group A patients
(376 ± 84 vs 184 ± 31 pg/ml)*, higher V (4.4 ± 1.0 vs 2.0 ± 0.4 cc/min)*,
higher FENa (2.30 ± 0.66 vs 0.64 ± 0.19)** and higher UNaV (511.1 ± 150.9 vs
83.9 ± 22.8 mmoles/min)**. The CVP was similar both before (10 ± 1 vs 9 ± 1 cm
H2O) and after volume expansion (16 ± 1 vs 15 ± 1 cm H2O)
in both groups.
We conclude that preserving the right atrial
appendage during open heart surgery significantly increases the release of ANH,
resulting in increased urinary sodium excretion and better diuresis in the post
operative period. *P < 0.05 **P < 0.02.
3:30 p.m. ADJOURN
*By Invitation
