Saturday Morning, May 17, 1958
8:30 A.M. Scientific
Session: THORACIC SURGERY FORUM - Imperial Ballroom
12. The
Simplified Stationary Screen Pump Oxygenator.
Jerome Harold Kay (by invitation)
and Robert M. Anderson
(by invitation), Los Angeles, Calif.
In 1956 at The Surgical Forum of The American College
of Surgeons, one of us (JHK) described a simplified screen-type pump oxygenator
with flow equal to normal cardiac output. This apparatus oxygenated blood by
passing a film of blood on stationary screens in an atmosphere of oxygen. The
blood was pumped by two roller pumps. The results with this apparatus have been
very good. Recently we have greatly simplified and improved this apparatus so
that the entire oxygenator, coronary sinus reservoir, venous reservoir, air
trap and filter are combined into one chamber. This eliminates the connections
on the arterial side and decreases the priming volume. One of the most
important improvements consists of an automatic filmer. This completely
eliminates saline to start a film. The apparatus is far simpler to use than a
bubbler and is less traumatic to the blood elements. It can be run by one
person. It is now being used clinically.
13. Comparison of Relative
Merits of Occlusive and Non-Occlusive Pumps for Open Heart Surgery.
Paul C. Hodges (by invitation), C. Walton Lillehei, Richard Cardozo
(by invitation), Andre Thevenet (by invitation), Minneapolis, Minn.
Both occlusive and non-occlusive types of pumps have
been recommended for open heart surgery. In general these recommendations have
been based upon personal preference or sentiment rather than on factual
comparative data.
At the University of Minnesota Heart Hospitals more
than 450 patients have had open heart surgery utilizing a pump perfusion
system. More than 50 of these clinical perfusions have exceeded a duration of
50 minutes. This clinical experience has been obtained using either an
occlusive or non-occlusive pump of several designs. The clinical experience has
been supplemented by an extensive laboratory investigation encompassing
controlled observations on variables.
Analysis of this experimental and clinical data makes
possible some definite conclusions as to the relative merits of occlusive
versus non-occlusive pumps. These conclusions are based upon analysis of (1)
ability to maintain blood pressure in the perfused subject, (2) evidence of
blood trauma (hemolysis, protein denaturation, bleeding, and platelet
destruction), (3) ease of flow regulation, and (4) operative risk.
14. Cardiac
By-Pass Without Artificial Oxygenator.
W. T. Mustard (by
invitation), W. Sapirstein (by
invitation)
and Denise Pay (by
invitation).
Sponsored by F.
G. Kergin, Toronto, Canada
Cardiac by-pass is accomplished without the use of an
oxygenator by perfusing the aerated lung fields. Avoiding an artificial
oxygenator reduces extra-corporeal handling of the blood and consequently the
effects of blood damage. An extended period of cardiac by-pass is thus
permitted enabling intracardiac surgical correction of some of the more complicated
defects.
An operative technique is described together with
experimental results. Using conventional cardiac pumps, vena caval return is
perfused through the pulmonary circuit. Oxygenated blood returning to the left
atrium is cannulated into a reservoir from where it is further pumped into the
systemic system. With the heart in asystole, a distended rubber balloon has
been developed to occlude the mitral valve orifice, ensuring dry right and left
ventricles even in the presence of septal defects.
The results of animal experiments suggest the
superiority of this by-pass procedure for the treatment of selected cardiac
anomalies over presently used systems with extracorporeal oxygenation.
15. Monitor and Control of Blood Oxygen
Tensions and pH During Total Body Perfusion.
Leland C. Clark, Jr. (by invitation), Samuel Kaplan (by invitation),
Edward C. Matthews (by invitation), F. Kathryn Edwards (by invitation)
and james A. helmsworth, Cincinnati, Ohio
There is a need for a relatively simple method to continuously
monitor the oxygenation of blood and carbon dioxide exchange during total body
perfusion for direct vision intracardiac surgery. Measurements of blood
saturation are unsatisfactory because during perfusion the oxygen tension of
blood is frequently considerably above normal arterial tensions.
For the last several years we have used polarographic
methods to record arterial and venous blood oxygen tensions during
cardiopulmonary bypass. This method which is applicable to any extracorporeal
system has the following advantages: (1) Continuous records of absolute oxygen
tension over long periods of time are obtained. (2) The oxygen electrode adds
only a few square millimeters of polyethelene to the system. (3) Neither the
cathode nor the anode is in contact with the blood, and no voltage is impressed
in the blood. (4) The electrode gives a linear response in current flow to a
linear increase in oxygen content. (5) The speed of response is full scale in
approximately five seconds. (6) The electrode is insensitive to changes in pH.
Continuous records of the pH of arterial blood are
routinely obtained during cardio-pulmonary bypass. This information has been
very helpful in the monitoring of carbon dioxide exchange in bubble
oxygenators. Respiratory acidosis or alkalosis can be prevented by varying the
gas flow and size of the oxygen bubbles in the extracorporeal circuit.
The details of these two methods will be described and
their value will be demonstrated in the monitoring of human perfusions.
16. Experimental
and Clinical Studies of Controlled Hypothermia Rapidly Produced and Corrected
by a Blood Heat Exchanger During Extracorporeal Circulation.
Ivan W. Brown, Jr. (by invitation), Wirt W. Smith (by invitation),
W. Glenn Young (by invitation)
and W. C. Sealy,
Durham, N. C.
A simple blood heat exchanger capable of use with any
type of heart-lung machine has been developed by our laboratory. Experimental
studies with the exchanger of the cooling and rewarming velocities of various
tissues such as the brain, heart, kidney, liver, intestinal tract, and muscle
masses have been determined for various body flow rates, inflow blood
temperatures and arterial inflow sites. The exchanger permits a lowering of
vital organ temperatures as rapid as 1.0° C. per minute for the range from 37°
C. to 30° C. with a slightly slower rewarming velocity. In most instances, the
mid-esophagus temperature closely follows the intracardiac temperature curve.
Changes of heart, kidney, intestinal, cerebral, and mixed body A-V oxygen differences
during cooling and rewarming were determined for various total body inflow
rates. No toxic or deleterious effects on the blood have been noted on rapidly
removing or adding heat to the inflowing blood over a wide range of
temperatures from 0.5° C. to 42° C.A specially designed bubble trap
used with the exchanger for excluding oxygen bubbles which might be released
from the oxygen saturated rewarming plasma will also be described. A summary of
our clinical data from more than 12 open heart operations will be presented
which indicates the many complementary advantages of combining hypothermia and
extracorporeal circulation particularly when controlled hypothermia can be
achieved rapidly at any time during operation and similarly corrected.
17. Cerebral Blood
Flow and Brain Volume Changes in Extra-corporeal Circulation.
Max M. Halley (by invitation), Keith Reemtsma (by invitation),
Manuel Bresler (by invitation) and
Oscar Creech, Jr.,
New Orleans, La.
Cerebral Damage may be evident in the early postoperative
period following extracorporeal circulation. This phenomenon is sometimes
suggestive of cerebral edema, and may be completely reversible.
Two groups of animal experiments are being conducted in
order to clarify the pathogenesis of the syndrome: The first group involves
direct measurement of cerebral blood flow during extracorporeal circulation by
means of a magnetic rotameter. It includes determination of cerebral oxygen
consumption at different rates of flow; determination of the arterial-venous difference
of glucose, pyruvate, and lactate in the cerebral circulation; and measurement
of arterial and venous pO2 and pCO2.
The second group involves the measurement of central
venous pressures and cerebro-spinal fluid pressure during extracorporeal circulation,
and subsequent determination of brain volume changes by the method of White,
immediately and at intervals after extracorporeal circulation. Correlation
between brain volume changes and the variables of both groups is being
attempted.
Results to date in the first group indicate that (a)
Cerebral flow during extra-corporeal circulation is directly proportional to
systemic blood pressure and is reduced to very low levels during hypotension
(b) Perfusion rate is not a good index of cerebral flow (c) Cerebral oxygen
consumption falls markedly at low levels of cerebral blood flow (d)
Vasopressors, such as nor-adrenalin increase cerebral flow by elevating the
systemic blood pressure (e) Glucose levels of venous and arterial cerebral
blood show no definite variation during extracorporeal circulation (f) Increase
in pCO2 does not appear to increase cerebral flow.
Results in the second group to date indicate that (a)
Brain volume may be significantly increased after extracorporeal circulation
(b) Spinal fluid pressure may be elevated to various degrees during
extracorporeal circulation, even in the presence of normal venous pressures,
particularly at high rates of perfusion (c) Marked spinal fluid pressure
increases occur in the presence of elevated venous pressures, particularly in
the superior vena cava (d) No definite correlation has yet been established
between venous or spinal fluid pressure changes and post-operative increase in
brain volume.
18. Clotting
Deviations in Man During Cardiac By-Pass: Fibrinolysis and Circulating
Anticoagulant.
Kurt Von Kaulla (by invitation) and
Henry Swan, Denver, Colo.
Serial coagulation studies before, during, and after
heart surgery using a fixed screen oxygenator with DeBakey pumps reveal that
two major deviations from the normal coagulation process may occur. One is a
very marked increase in the fibrinolytic activity of the plasma reaching a peak
during or immediately following the by-pass procedure. This was a persistent
finding in patients with a perfusion rate of 55-70 ml/kg/min. (9 out of 9
patients). Fibrinolysis was less pronounced with a rate of 100-110 ml/kg/min.
(1 out of 1), and was absent with a rate of 190-200 ml/kg/min. (2 out of 2).
The euglobulin technique, permitting early recognition of fibrinolytic activity
in heparinized blood, was used. The plasminogen activator in the urine rose to
high levels shortly before or during the fibrinolytic phase; dropped to zero in
the following hours; and returned to normal after several days. It is suggested
that a tissue activator is released during the operative trauma, particularly
during the pump-dependent phase, which subsequently activates the blood
plasminogen. The intensity of the reaction may be related to the COa tension.
The second phenomenon, independent of the perfusion
speed, is the appearance of a powerful anticoagulant as measured by the
thrombin time. It develops after protamin neutralization of the administered
heparin and may persist from minutes to hours. Neither fibrinolysis nor the
circulating anticoagulant per se necessarily create clinical hemorrhage,
but hemorrhage can occur if both phenomena overlap. In 2 patients out of 20,
clinical hemorrhage was evident.
19. Elective Cardiac
Arrest: The Relationship of Elevated Intra-cardiac Pressures to Subsequent
Myocardial Function and Pathologic Pulmonary Changes.
John Ross,
Jr. (by invitation), Joseph W. Gilbert, Jr. (by invitation),
Edward H. Sharp (by invitation) and Andrew G. Morrow,
Bethesda, Md.
Cardiac failure, ventricular fibrillation and pulmonary
parenchymal changes sometimes follow elective cardiac arrest during
cardiopulmonary bypass. A study was undertaken to define more precisely the
central hemodynamic effects of perfusion with cardiac arrest and to determine
the relationship of these changes to the above complications.
With a Melrose pump-oxygenator, 31 dogs were subjected
to total cardio-pulmonary bypass. Pressures in the left atrium, right
ventricle, and aorta were recorded throughout perfusion and recovery. Control
and post-perfusion lung biopsies were obtained.
Seven of the 31 dogs underwent perfusion without
cardiac arrest or cardiotomy. Left and right heart pressures remained low
during perfusion, cardiac failure following bypass was not encountered, and
post-perfusion lung biopsies were normal. In the remaining 24 dogs, cardiac
arrest was induced with potassium citrate. In seven of these animals, right
atriotomy was maintained throughout the arrest and recovery periods.
Intracardiac pressures did not arise, and cardiac failure occurred in only one
dog. In four dogs in which cardiac arrest was induced without atriotomy, left
and right heart pressures showed progressive elevations during arrest.
Following arrest, ventricular fibrillation occurred in two dogs, and three
animals developed cardiac failure. Lung biopsies in two of these showed
perivascular edema and hemorrhage. In the remaining 13 dogs, right atriotomy
was performed immediately before arrest was terminated. Although the elevated
intracardiac pressures returned to normal with right atriotomy, complications
were no less frequent. Clamping the pulmonary artery during arrest prevented
right ventricular pressure elevation, and augmented left atrial pressure
increase.
During cardiac arrest bronchial arterial blood flows
into the left heart, and also reaches the right heart through a collapsed
pulmonary valve. Without cardiotomy, the resulting change in diastolic
myocardial fiber length imposed by dilatation may often result in cardiac
failure, sometimes associated with lung damage. Both left and right heart
distension can be prevented by right atriotomy alone, provided the pulmonary
valve remains incompetent. The importance of these findings in the management
of patients undergoing elective cardiac arrest will be discussed.
20. Lung Lymph in Experimental
Pulmonary Edema.
A. Robert Cordell (by
invitation}, Winston-Salem, N. C., Richard
A.
Bahn (by
invitation), Buffalo, N. Y., James C. Stephens (by invitation),
Buffalo, N. Y. and H. H. Bradshaw,
Winston-Salem, N. C.
A technique has been developed whereby lymph can be
collected from the right lymphatic duct in the neck of dogs. It will be shown
by means of dye injection studies that in approximately fifty per cent of dogs
this lymph comes directly from the lungs without mixing with chyle from the
thoracic duct. Thirty-five animals have undergone successful right lymphatic
duct cannulation.
Control studies of lung lymph have been carried out on
sixteen dogs with the following results: Flow rate ranges from 0.1 to 1.3 cc.
per hour. Positive pressure respiration doubles this output in the average dog.
Total protein content is approximately one-half that of circulating plasma.
Sodium level averages 145 milli-equivalents per liter and chloride content 140
milli-equivalents per liter. Potassium level varies from 2.8 to 4.2 milligrams
per liter.
Experimental pulmonary edema has been produced by the
intravenous injection of alpha naphthyl thiourea in the dosage of 50 milligrams
per kilogram.
Studies of pulmonary lymph during development of this
fatal condition have shown the following results: Pulmonary lymphatic flow
rises sharply to levels of 12 to 15 cc. per hour. Protein content shows a rise
from 3.0 to 4.0 grams per cent. Sodium, potassium, and chloride concentrations
show relatively little change.
Pulmonary edema has also been produced by means of
creating aortopulmonary artery fistulae. Studies of lung lymph in these animals
have shown close correlation with those from dogs in which pulmonary edema was
drug-induced.
This technique is presently being used in the
laboratory in an attempt to increase our knowledge of pulmonary lymphatic
physio-pathology.
21. The Effect of Position on
Pulmonary Ventilation.
Thomas F. Nealon, Jr. (by invitation) and
John H. Gibbon, Jr., Philadelphia, Pa.
It has been stated that it is more difficult to provide
adequate pulmonary ventilation for anesthetized patients in the lateral
position than in the supine position. As the lateral position is frequently
used in thoracic surgery, we undertook to determine whether a greater minute
volume ventilation was required in this position than in the supine position.
For the purposes of this study, adequate pulmonary
ventilation was taken to be the minute volume ventilation required to maintain
the pCO2 of arterial blood at its preoperative level. The pCO2
of the expired gas was measured continuously by an infra-red absorption carbon
dioxide analyzer. Periodic checks were made by gas analysis of arterial blood
samples. Ventilation was provided by an intermittent positive and negative
pressure ventilator attached to a closed-circle anesthetic machine with a
cuffed endotracheal tube. The minute volume ventilation was measured by a gas
flow meter in the expiratory line. Determinations were made on the same
patients in the supine and the lateral positions before and after the
intrathoracic portion of the operation.
No increase in ventilation was found to be required
when the patient was turned to the lateral position from the supine position.
An open thoracotomy did not alter these findings when the lung was not
retracted or compressed.
22. Aortic Homograft Replacement
of the Main Pulmonary Artery.
George Robinson (by invitation), Philip Glotzer (by invitation),
Marvin Gilbert (by invitation) and
Elliott S. Hurwitt,
New York, N. Y.
Two techniques have been developed in dogs for
replacement of the main pulmonary artery and its bifurcation by an aortic
homograft. One method includes the use of cardiopulmonary by-pass and elective
cardioplegia. The second procedure may be accomplished without temporarily
replacing the heart and lungs or interrupting the circulation, by employing a
side-to-side anastomosis between the anterior wall of the main trunk of the
pulmonary artery and the posterior wall of the mid-portion of the graft.
Evaluation of the fate of the grafts in long-term surviving animals includes
angiocardiography and histologic study. The potential clinical applications for
pulmonary arterial replacement include atresia of the pulmonary artery (either
as a solitary lesion or as a component of the Tetralogy of Fallot); chronic
thrombotic occlusion of the pulmonary artery; coarctation of the pulmonary
artery; and involvement of the pulmonary artery by aneurysms, tumors, or
trauma.
23. Experimental Results with a
Prosthetic Aortic Valve.
Benson B. Roe, John W. Owsley (by invitation) and Peter C.
Boudoures (by invitation), San Francisco,
Calif.
A collapsible plastic intraluminal valve has been
constructed for intravascular implantation and a suitable technique has been
developed for placing this valve into the ascending aorta of experimental
animals without total circulatory arrest or bypass. Three years' experience
with various modifications of a tubular flexible tricuspid prosthetic valve has
resulted in many improvements to reduce resistance and clotting. The physical
properties of the silicone material are excellent in strength and resilience;
stress studies reveal no significant fatigue, and no surface clotting or loss
of flexibility has occurred after several months of function. Problems of
adjacent clotting and embolization will be discussed and preventive measures
presented.
Satisfactory coronary artery flow is maintained with a
completely competent valve distal to the ostia. At least three dogs are living
with valves functioning for six months and one survived secondary avulsion of
the anatomical cusps. A large number of shorter survivors have demonstrated
tolerance to the position of the prosthesis, and pressure studies indicate
minimal resistance across the valve and total competence to pressures well
above 300 mm. Hg.
Technical and physiological material will be presented
to demonstrate the valve action and competence under mechanical stress, while
functioning in the ascending aorta, and after long-term implantation.
24. Postmortem
Perfusion Studies in the Evaluation of Techniques of Aortic Valvulotomy.
W. Gerald Austen (by
invitation), Robert S. Shaw (by invitation),
W. M. Thurlbeck (by
invitation) and J. Gordon Scannell,
Boston, Mass.
During the past two years the hearts of 25 patients
dying with severe aortic stenosis have been studied by perfusion of the aortic
valve so as to determine quantitatively the degree of aortic stenosis and
regurgitation. The valves were subsequently restudied after the performance of
reconstructive procedures. The following observations were made. (1) Closed or
"blind" commissurotomy or dilatation usually results in a forbidding degree of
regurgitation and inconsistent relief of stenosis, often with release of gross
calcareous emboli. (2) Debridement and commissurotomy under direct vision
consistently allows adequate relief of stenosis without producing significant
regurgitation and without the uncontrolled release of emboli. (3) Anatomic
identification of the commissure is the key to successful commissurotomy. After
debridement accurate definition of the valvular landmarks is possible. (4)
Inspection of normally functioning valves and perfusion studies have shown that
valve leaflets may be normally fused to a point 2 mm. from the aortic wall and that
division of adherent leaflets beyond this point affords no decrease in valvular
resistance to forward flow but may increase the degree of regurgitation.
The application of these principles in a limited number
of operative cases is described.
25. Intercoronary Collaterals in
Normal Hearts.
Sven Bellman (by invitation) and Howard A. Frank, Boston, Mass.
For an understanding of the vascular response to the
narrowing or occlusion of coronary arteries and the variation in the adequacy
of this response from individual to individual, an accurate knowledge of the
numbers, dimensions, locations, pathways, and connections of intercoronary
collateral channels in normal hearts seems essential. This information should
also be helpful in the planning of surgical efforts to increase coronary
collaterals.
Most current knowledge of intercoronary communications
in normal hearts has been gained by indirect means, such as the measurement of
retrograde pressures and flows, or the demonstration of the interarterial
passage of test substances. The connecting vessels themselves cannot usually be
demonstrated in normal hearts by standard dissection, histological or
radiological technics. Microradiography, applied stereoscopically following the
injection of suitable contrast media, has been used successfully to demonstrate
the finest vascular elements of many tissues and is well suited to an
investigation of the intercoronary vessels.
The present paper presents the results of a post-mortem
stereomicroradiographic study of the intercoronary vessels in normal human
hearts, and, for correlation of experimental with clinical observations, in the
hearts of commonly used laboratory animals as well.
26. Changes in
Pulmonary Artery Pressure During Cardiopul-monary By-Pass: An Experimental
Study.
James B. Littlefield (by invitation), J. Francis Dammann, Jr.,
Phyllis R.
Ingram (by invitation) and
William H. Muller, Jr.,
Charlottesville, Va.
Pulmonary complications associated with cardiopulmonary
by-pass may be transient or result in fatal hemorrhage and edema. This
experimental study was performed to evaluate pulmonary artery pressure changes
during cardiopulmonary by-pass in dogs with a normal and increased collateral
pulmonary circulation.
Acute experiments performed on seventeen dogs employed
cardiopulmonary by-pass at intervals up to two hours, using a high flow,
bubble, pump-oxygenator. The pulmonary artery and aorta were clamped
simultaneously and cardiac standstill induced. Left auricular, pulmonary and
femoral artery pressures were monitored and lung biopsies obtained. A right
cardiotomy was employed. Left pulmonary artery ligation (termed "physiological
pneumonec-tomy") performed in five dogs, several months before evaluation,
simulated increased collateral pulmonary circulation seen in certain congenital
cardiac patients.
|
RESULTS:
|
Pulmonary Artery Pressure mm. Hg.
|
|
|
Normal
Dogs
|
"Physiological Pneumonectomy" Dogs
|
|
1. Before
Standstill:
|
Below 24
|
Up to 48 (Intermittent)
|
|
2. During
Standstill: (30 - 60 minutes)
|
Below 30
|
60-80 (Persistent with
hemorrhage in 10-30 min.)
|
|
3. After
Standstill:
|
Up to 65 (Intermittent)
|
30-50 (Intermittent)
|
SUMMARY:
1) Pulmonary hypertension was not a problem
before standstill but persisted in the "physiological pneumonectomy" dogs
during standstill, accompanied by severe hemorrhage.
2) Both groups of dogs showed intermittent
pulmonary hypertension during cardiac recovery until the left ventricle
functioned efficiently.
3) Accumulative periods of pulmonary
hypertension may produce lung complications at any time during cardiopulmonary
by-pass.
4) Pulmonary hypertension during
cardiopulmonary by-pass may be reduced or prevented by: an unoccluded pulmonary
artery, left auricular decompression, prompt return of left ventricular
function, maintenance of normal systemic blood pressure and delayed cardiotomy
closure.
