TUESDAY MORNING, APRIL 19, 1977
8:30 A.M. Scientific Session Grand Ballroom
13. Management of the Pacemaker Recall
DAVID C. MACGREGOR*, EDWARD J. NOBLE*, JOHN D. MORROW*,
HUGH E. SCULLY*, H. DOMINIC COVVEY*
and BERNARD S. GOLDMAN, Toronto, Ontario, Canada
Rapid technological changes in the medical devices
industry have led to an alarming deterioration in the reliability and safety of
the cardiac pacemaker. During the past four years, we have been subjected to
eight pacemaker recalls involving 469 pulse-generators (31.9% of our total of
1470 implants).
Upon notification of a pacemaker recall, it becomes the
implanting physician's responsibility to verify the manufacturer's list of
affected units and to make a frank disclosure in person to the patient and/or
responsible relatives. Appropriate communications must also be established with
government agencies, the news media, malpractice insurance carriers and local
hospital boards. Although a pacemaker manufacturer may initiate a recall and
make recommendations as to whether or not an individual pulse-generator should
be replaced prophylactically or subjected to increased surveillance, these
decisions rest primarily with the implanting physician.
To date, 138 (29,4%) of our recall pacemakers have been
replaced because of unpredicted failure, premature rate drop or fear of
catastrophic failure at a mean time of 10.6 months. Only 27 (5.8%) removed
units have thus far demonstrated a rate drop with battery depletion and 19
(4.1%) units have been replaced for other reasons. Patient deaths have
accounted for 69 (14.7%) units and 16 (3.4%) units have been lost to followup.
The remaining 200 (42.6%) recall pacemakers are under increased surveillance by
our pacemaker clinic. Transtelephone monitoring assumes a major role in the
management of the pacemaker recall, not only to predict, but also to identify
the failure of any individual unit. Schedules should be adapted to the expected
performance of suspect units and should be revised as circumstances dictate.
The authors wish to emphasize the need for improved
pacemaker standards and for more extensive biological testing of new pacemaker
models prior to release for human implantation.
*By invitation
14. The Changing Spectrum of Pericardiectomy for
Chronic Pericarditis: Occult Constrictive Pericarditis
JAMES W. KILMAN, CHARLES A. BUSH*, CHARLES F. WOLLEY*,
JOHN M. STANG*, JOSEPH TEPLY* and NOBUHISA BABA*,
Columbus, Ohio
During the past twenty-four years seventy patients have
had a total pericardiectomy at our institution. Fifty-nine patients had the
classic findings of constrictive pericarditis as the reason for their surgery
and operative mortality was five percent in this group. During the past few
years a new indication for total pericardiectomy has been found in twelve
patients. These patients have fatigue, dyspnea and chronic chest pain without
any of the other classic findings of chronic constriction. Coronary angiograms
have been normal. Cardiac catheterization following administration of a fluid
load of 1000 cc of warm normal saline during six to eight minutes resulted in
diastolic equilibration of pressures, constrictive pulse pressure contours and
loss of the normal right atrial response to inspiration in all of these
patients with occult constrictive pericarditis but in none of the six normal
controls. Total pericardiectomy has been done with ease in this group with no
morbidity or mortality. Relief of the symptoms has been dramatic. Repeat
cardiac catheterization following total pericardiectomy revealed normal hemodynamics
prior to and following fluid load. Tissue examination of the removed
pericardium revealed gross and/or microscopic changes of inflammatory disease
without calcification. Occult constrictive pericarditis appears to be a new
indication for total pericardiectomy and can only be defined by the hemodynamic
response to a rapid saline load.
*By invitation
15. Preliminary Clinical Experience with Isotonic
Hypo-thermic Potassium Arrest (KA)
G. FRANK O. TYERS, NORMAN J. MANLEY*, DENNIS R. WILLIAMS*
and MARK KURUSZ*, Hershey, Pennsylvania
The modalities of KA and 15°C perfusion hypothermia
were combined and used exclusively for myocardial protection (MP) in 70
consecutive patients (pt(s). Following aortic cross-clamping (X) the arrest
solution: 275 m0sm, pH 7.7, 2500 u heparin and in meq/L:Na 141, K 25, C1 101,
Ca 1.1, Mg 3, was perfused through a DeBakey cannula continuously (up to 3L)
during direct coronary surgery (ACB), intermittently during multiple valves
(2VR, 3VR) and once (½ to 1L) prior to single valve replacement (AVR or MVR).
Left ventricular wall temps fell to 16-17ºC. Mean X time was 65 min. Preop all
pts were NYHA Class III or IV, over 60% had ejection fractions < 0.50, 7 had
main left stenoses (2 with tight AS), 5 were redos, 20 had recent M infarction,
8 were emergent, 2 were Jehovah's Witnesses, age ranged from 6 to 76 yrs. 30
day mortality was 4/70, < 6%. No death was related to M depression. There
were 14 AVRs, 5 MVRs, 6 2VRs, 1 3VR and 5 combined VR + ACB with 2 deaths,
6.6%, 1 due to right coronary injury in a triple redo AVR with collagen
disease, 1 due to hemorrhage in a 2VR, double bypass pt with functional
platelet abnormality. No primary, single or multiple valve pt died. There were
35 ACBs with a mean of 3 grafts, with 1 death, 2.9% in a post MI, CHB pt with
ungraftable vessels. Although several pts required preop balloon assist, this
was the only pt to require postop assist and to leave the OR alive who
subsequently died. There were 4 congenital cases with 1 death due to poppet dysfunction
in a tunnel AS with AVR and ascending aortic graft.
As evidence of excellent MP, postop pressors were
used briefly in less than 11% of pts, a greater number required postop
antihypertensives, over 50% defibrillated spontaneously immediately following X
release, the rest required only a 5 watt sec shock. Both cardiac output, 5.6
±.3 L/min and cardiac index, 2.7 ±.1 L/min/m2 were immediately
improved versus preop levels in the same pts while awake and anxious at cardiac
cath (p <.05) and mean postop MB-CPKs were not significantly elevated at 12
(16 ± 3) and 24 hrs postop (15 ± 6 u/L). Respirator, ICU and hospital days,
mean blood used/patient (3.6 + .3 u), and mean bypass time (94 min) were all
equal or better than with coronary perfusion.
The significant advantages of 15°C KA are: 1)
simplified high volume aortic root perfusion, effective even with 4 + AI, 2)
the preclusion of the "calcium paradox", 3) minimization of defibrillator
induced M injury, 4) operating conditions superior to normothermic ischemic
arrest or topical hypothermia, 5) avoidance of coronary artery trauma and 6)
extensive clinical and experimental evidence of superior MP.
*By invitation
16. Prolonged Safe Aortic Cross Clamping by
Combining Membrane Stabilization, Multi-dose Cardioplegia and Physiologic
Reperfusion
DAVID FOLLETTE*, KLAUS FEY*, DONALD G. MULDER,
JAMES V. MALONEY, JR. and GERALD BUCKBERG,
Los Angeles, California
We have shown that 1) continuous adequate perfusion of
the beating heart, although cumbersome, prevents low output syndrome and 2) the
superb operating conditions of arrest cannot be achieved safely with
hypothermic (perfusion or topical) ischemic arrest; deleterious changes in LV
flow, distribution, metabolism, compliance and function occur after only one hour
of cross clamping. This study tests the hypothesis that prolonged (2 hours) of
safe arrest is possible by combining membrane stabilization,
cardioplegia, and physiologic reperfusion during cross clamping.
Methods: We studied 32 dogs using standard cardiopulmonary
bypass. Ten dogs (control) underwent ischemic arrest with topical hypothermia
(LV temperature 16°C) for 1 hour. To increase the safety of 1 hour of
hypothermic arrest, we tested the effects of a) membrane stabilization
(procaine HC1) (5 dogs), b) cardioplegia (500 cc of 4°C KC1, glucose, insulin,
THAM, plasma, albumin) (6 dogs) and c) reperfusion (just before unclamping)
with 500 cc blood buffered to pH 7.8 (5 dogs). In 6 dogs, we prolonged cross
clamping to 2 hours by combining membrane stabilization,
cardioplegia (replenishing 100ml each 20 min.) and pH 7.8 reperfusion. We
measured regional coronary flow (microspheres), LV O2 uptake,
compliance (intraventricular balloon) and performance (isovolumetric curves)
before and 30 minutes after arrest.
Results: The deleterious effects of 1 hour of ischemic
arrest with topical hypothermia (LV compliance fell 53% ± 6*ŧ,
LV performance fell 43% ± 3*) were improved substantially by membrane
stabilization alone, cardioplegia alone, and pH 7.8 reperfusion alone;
postischemic values did not, however, return to normal. In contrast, 2 hours
of cross clamping with combined membrane stabilization, cardioplegia and
physiologic reperfusion resulted in 1) highest LV flows (150 ± 21 cc/100
gm/tnin*), 2) most favorable flow distribution (endo/epi 2.0 ± 0.3*), 3)
greatest LV 02 uptake (0.06 ± 0.01cc/100 gm/beat*), 4) best LV compliance (87%
± 5 recovery*), and 5) normal (100% recovery*) post-ischemic function.
Conclusions: We conclude
that combining membrane stabilization, multi-dose cardioplegia and physiologic
reperfusion allows aortic cross clamping in the normal heart for up to 2 hours
with as much safety as if the coronaries were perfused continually with
oxygenated blood.
* = p<0.01 ŧ
= ±SEM
INTERMISSION - VISIT EXHIBITS
*By invitation
17. Haemodynamic Evaluation of Left Ventricular
Bypass Using a Homologous Cardiac Graft
JACQUES G. LOSMAN*, ALAN G. ROSE* and CHRISTIAAN BARNARD*,
Cape Town, South Africa,
Sponsored By: THOMAS D. HARTLEY, Gainesville, Florida
A valid criticism of orthotopic cardiac transplantation
for irreversible left ventricle disease is that a normal or slightly diseased
right ventricle is removed, and that a number of patients in terminal cardiac
failure will not tolerate orthotopic transplantation due to excessively
elevated pulmonary resistance.
To overcome problems due to severe pulmonary
hypertension, an operation was devised in which the donor heart is used to
bypass the right and left ventricle of the recipient heart left in situ'. The
functional efficacy of the donor heart was assessed in 50 baboons after
inducing left ventricle failure by ligation of the left anterior descending
coronary artery l ½ cm. from its origin and creating severe supra-aortic
stenosis (peak systolic gradient of 80 to 100 mm Hg.). Haemodynamic studies
were performed during selective fibrillation of the recipient heart and during
synchronous and sequential pacing. It was found that volume load, ventricular
compliance and contractility were the major determinants of the recipient and
donor heart function. After-load changes played a lesser role.
It was found that the recipient heart ejection fraction
and maximal total cardiac output were significantly improved by sequential
pacing with optimalised delays. Low mortality, good donor heart function and
prolonged survival were obtained despite lethal damage to the recipient heart
(100% controls died).
Right and left ventricular bypass transplantation
minimised recipient heart post-infarction arrhythmias, reduced myocardial
necrosis area and allowed tolerance of severe supra-aortic stenosis. It is,
therefore, a useful therapeutic variant of orthotopic cardiac transplantation
and has been used successfully in seven human patients.
*By invitation
18. Prognostic Indices for Survival During
Post-Cardiotomy IABP Pumping: A Simple Method of Scoring with Left Ventricular
Assist Device Implications
JOHN C. NORMAN, DENTON A. COOLEY, STEPHEN R. IGO*,
C. WAYNE HIBBS*, J. GRAEME BENNETT* and
JOHN M. FUQUA*, Houston, Texas
Intraaortic balloon pumping has gained acceptance
as a valuable adjunct in weaning patients from cardiopulmonary bypass. From Sept.
30, 1975 - Sept. 30, 1976, we have utilized IABP in 75 patients. Sixty-five
(81%) were male. There were 33 (44%) survivors; 29 were male. The mean duration
of IABP support was 55.4 ± 58hrs.
To clarify prognoses during IABP support, we have
analyzed: 1) hemodynamics [cardiac index & mean pulmonary capillary wedge
pressure]; 2) degree of pharmacologic support (reflected by systemic vascular
resistance); & 3) renal blood flow (reflected by urinary output) in 25
surviving and nonsurviving patients during IABP support over a total of 54.6
days. Each data point was obtained each hour for each variable, stored,
retrieved, analyzed, assigned a relative score of 0-4 & summed with a
modified Hewlett-Packard 5690B computerized catheterization system with a video
monitor and terminal.
Results: Survivors had IABP support for 103 i 28 hours;
nonsurvivors had support for 25 ± 13 hours. During the initial 12 hours,
survivor scores were 8.0 ± 1.9 and nonsurvivors were 5.4 ± 3.0 (N.S.).
Survivors' scores increased from initial values of 8.0 ± 1.9 during the initial
12 hours to 11.6 ± 1.5 during the final 12 hours (p<0.01). During the final
12 hours, survivors' scores were significantly higher (11.6 ± 1.5) than
nonsurvivors (4.8 ± 2.9), p
Serial monitoring and
scoring of post-cardiotomy IABP patients allows prediction of the outcome.
Patients with initial scores of 6.0 or less for 12 or more hours, appear
unsalvageable, short of implantation of a left ventricular assist device. The
latter has proven to be an order of magnitude more effective than IABP during
early clinical evaluations.
11:15 A.M. Address of Honored Speaker
PROFESSOR CHARLES DUBOST
Paris, France
*By invitation
