Wednesday Morning, April 22, 1959
8:30 A.M. Scientific Session: THORACIC SURGERY FORUM Pacific Ballroom
14. Metabolic
Acidosis and the Dissociation Curve of Hemoglobin During Extracorporeal
Circulation.
George J. Magovern (by invitation), Robert S. Cartwright
(by invitation), John F. Neville, Jr. (by invitation), and
Edward M. Kent, Pittsburgh, Pa.
Hypoxia during cardio-pulmonary bypass is frequently
the result of inadequate surface area exposure of the blood. This will result
in metabolic acidosis and further hypoxia due to a shift in the dissociation
curve of hemoglobin to the right. Despite careful evaluation preoperatively,
this apparent situation has been observed on several occasions during
approximately 100 clinical cases of extracorporeal circulation and stimulated
the present study, in an attempt to explain the cause and remedy the situation
during surgery. Experimental and clinical data are presented.
PROCEDURE: Twenty-five mongrel dogs between 18 and 30
Kg. were placed on total extracorporeal circulation using the Kay-Cross
Oxygenator. The pH, pO2, pCo2, Hgb., temperature, and
oxygen and carbon dioxide saturation were determined. Arterial and venous
pressures were monitored throughout and the flow rate was maintained at
approximately 70-100 cc/Kg. body weight. Hypoxia was then deliberately induced
by slowing the disc speed, resulting in inadequate surface area exposure. The
changes in all the above mentioned parameters were recorded and the pH was
brought down to approximately 7.0 to 7.1 range. Alkali, in the form of molar
sodium lactate or sodium bicarbonate was then added directly to the oxygenator
and the above data were recorded until the pH was in the normal or alkalotic
range.
Ten other mongrel dogs were placed on cardio-pulmonary
bypass using adequate surface area exposure and lactic acid was added to the
blood until metabolic acidosis resulted. The change in oxygen saturation and
its relation to the partial pressure of oxygen, as determined by the Clark
electrode, was determined.
The results will be described by graphs and the
relationships of the hemoglobin dissociation curve, pH, pCo2 and
oxygen saturation will be discussed. Clinical examples will be presented.
Methods for the management and prevention of metabolic acidosis occurring during
the use of a pump-oxygenator will be reviewed.
15. Studies
of a New Donor Blood Anticoagulant-Preservative Mixture for Extracorporeal
Circulation.
Wirt W. Smith (by invitation), Ivan W. Brown, Jr., W. Glenn
Young (by
invitation), and W. C. Sealy, Durham, N.C.
The acquisition of large quantities of fresh
heparinized blood for extracorporeal circulation is frequently a major problem
for blood banks, surgeons, patients and their families.
Heparinized blood has a short storage life. This
necessitates collecting all that will be required for a particular case within
24 to 30 hours before scheduled surgery. Occasionally, the extracorporeal
perfusion is cancelled or delayed after the blood has been collected.
Theoretically, this blood is then available for routine transfusion use.
Practically, however, its short storage life and heparin content limits safe
distribution, and most often it is discarded.
A system for collecting donor blood suitable for
extracorporeal circulation based on a new anticoagulant-preservative solution
(sodium edathamil, sodium gluconate, glucose, magnesium chloride) has been
under study for the past 1½ years. This system permits the accumulation of
donor blood up to 5 days prior to surgery. Blood thus collected, when not used
for extracorporeal circulation, may be used for routine transfusion after
storage up to 18-21 days.
The theoretical basis and fundamental studies of this
system will be presented. Results from our experimental studies and from over
60 clinical perfusions employing this system have more clearly denned the
relative importance of certain constituents of the priming and transfusion
blood, particularly the role of the ionic components, and the acceptable
variations which are physiologically tolerable under conditions existing during
extracorporeal circulation.
16. Simple,
Automatic, Self Regulating Heart-Lung Machine Pump.
Josh Fields (by invitation), Francis X. Byron, and
William C.
Dale (by invitation), Beverly
Hills, Calif.
This new pump principle utilizes compressed gas as its
motivating force and the design permits automatic self regulation. The pump
chamber is completely non-traumatic to blood and consists of a rolling
diaphragm with no rubbing surfaces. The volume flow is infinitely variable to
over 20 liters per min. The pump rate (volume) automatically adjusts to
maintain the desired blood pressure and/or flow in the patient due to the
inherent feedback control system design. The pumping pressure is also variable
and accurately controlled. The rate is sensitive to the level of blood in the
arterial reservoir and can change with varying volumes. An inherent safety
feature stops the flow if the reservoir is empty and will not permit air to be
pumped.
The multiple safety and self regulating features are
part of the mechanical principles of the design and do not depend upon
accessory electronic circuits.
The entire assembly consists of three separate pump
units each capable of putting out 20 liters per min. and is remarkably simple,
inexpensive and weighs less than 30 lbs. Three separate pumps are contained
within a space 12x10 inches and the entire pump unit can be autoclaved
assembled. It is small enough to be placed in strategic position at the head of
the operating table where the pump operator can also follow the progress of the
surgery.
Any desired oxygenation may be used with this pump
unit.
17. An
Improved Inexpensive Automatically Controlled Pump-Oxygenator.
Adman Kantrowitz (by invitation), and Donald Abelson (fey invitation).
Sponsored by Alfred Hurwttz, Brooklyn,
N.Y.
A simplified pump-oxygenator employing a constant,
precise, and totally automatic control mechanism has been designed for improved
extracorporeal circulation. It consists of a rotating convoluted disc
oxygenator operated on the gravity flow principle. The separate venous
reservoir is eliminated and a single arterial line pump is used. The output of
this pump is automatically controlled by a photo-electric device, which
responds to minute increments in the patient's central venous pressure during
perfusion. The mechanism of the controlling unit will be described along with
the absolute safeguards to insure high reliability.
Among the advantages of the system are:
1. The
elimination of the venous line pump and the consequent diminution in the trauma
to the formed elements.
2. Complete
automation.
3. A highly
reliable automatic control.
4. A
completely autoclavable system.
5. A fixed
volume at all times in the extracorporeal circuit.
18. An
Externally Valved Hydraulic Cardiac Substitute.
I. A. Breckler (by
invitation), R. L. Ginsberg (by
invitation),
C. L. Portnoff (by
invitation), and Jack L. Bitterly
(by
invitation), Encino, Calif.
A cardiac pump is presented which has no internal
valving and which utilizes tubing of uniform diameter from cavae to artery.
Energy is imparted to the surface of tygon tubing through sterile saline.
Valving is accomplished by two asynchronous pressure bars at either end of a
small chamber. The entire unit is assembled and then autoclaved. Blood is
ejected from the pump with a minimum of trauma. Pulse rate, stroke volume, and
pulse characteristics are individually controlled.
Data are presented which compare the effect of this
pump, the Sigmamotor pump, and the DeBakey pump on blood by studying serum
hemoglobin and proteins, red blood cells and platelets before and after
prolonged perfusions.
The hydraulic pump is found to be the least traumatic
to blood of the three pumps studied. In addition the hydraulic pump is
considerably more adaptable to varying conditions of perfusion technics.
19. Physiological
P Wave Cardiac Stimulator.
Sam E. Stephenson, Jr. (by invitation), W.
H. Edwards
(by invitation), P. J. Jolly (by
invitation), and
H. W. Scott, Jr., Nashville,
Tenn.
In the past year the use of external cardiac pacemakers
in the treatment of post-surgical heart block has become common practice. The
units in use must utilize empirical rates of cardiac action and bear no
relation to the physiological rate of the heart in response to the
post-surgical state, temperature elevation, or activity.
We have developed an electronic device whereby the
normal auricular P wave can be monitored, amplified and used to trigger a
mechanical ventricular stimulator. In the case of complete heart block normal
ventricular rates for that particular individual are then obtained under all
circumstances.
The unit has been evaluated on approximately
thirty-five animals who have undergone complete destruction of the bundle of
His. Use of the P wave stimulator immediately returns to normal the elevated
venous pressure, decreased arterial pressure, decreased rate and decreased
cardiac output. These studies show an improvement in function from that
obtained from the use of a conventional pacemaker. Clinical application will be
discussed.
20. "Tranquilization"
of the Heart with the Ataractic Drugs.
Russell M.
Nelson, Salt Lake City, Utah
Irritability of the heart continues to be a problem for
the surgeon operating upon patients with cardiac malformations. Interest in the
effects of the ataractic-antihistamine group of drugs as possible cardiac
"tranquilizers" was first evoked in this laboratory with the observation that
high doses of diphenhy-dramine (Benadryl) injected into the coronary
circulation of the dog heart caused cardiac arrest and a stable heart in the
recovery period of perfusion.
Isolated dog heart preparations employing controlled
perfusions from a donor dog were used for this study. Temperature, perfusion
flow rates and pressures were regulated and electrocardiograms recorded from
the surface of the heart. After ventricular fibrillation was established by low
(3-15) voltage electric shocks, perfusion of the coronary circulation with
hydroxyzine (Ata-rax), 50 mg. in 4 to 6 minutes, was added. Conversion to
normal sinus rhythm regularly followed. Moreover, the hearts became resistant
to further attempts to induce ventricular fibrillation with the usual low
voltage shocks. To date, 23 isolated heart experiments with these findings have
been performed. Further work is under way with WIN 5494 (a coronary
vasodilator), and other related ataractic drugs which will be reported.
21. The Mechanism of Ventricular Fibrillation and
Cardiac Arrest During Surgery.
Archer S. Gordon (by invitation) and John C. Jones, Los Angeles, Calif.
Prevention is the most rewarding approach to the
problem of ventricular fibrillation and cardiac arrest during surgery. This
requires an understanding of the basic etiologic mechanisms underlying these
phenomena.
Anoxia, hypercarbia, hemorrhage, stress, reflexes and
drugs have been implicated in the production of cardiac arrest and ventricular
fibrillation. However, the exact mechanism by which these act during surgery
has not been detailed previously. Now experimental studies have revealed that
the production of ventricular fibrillation is a result of explosive ionic
imbalances acting on the myocardium. Extreme potassium alterations from
endogenous sources can occur on a second-to-second basis as a result of anoxia,
COg excess, stress, hemorrhage, etc., acting alone or in combination. It has
been possible to determine the exact degree of hyperpotassemia resulting from
each of these factors and the exact serum potassium level and time: dose
relationship required to produce fibrillation.
Carefully graded potassium injections can also produce
either ventricular fibrillation or cardiac arrest. However, the amounts
required to produce cardiac arrest are so large that they cannot be attained
from endogenous sources. Accordingly, cardiac arrest on a clinical basis is due
primarily to severe myocardial anoxia.
Clinical cases of ventricular fibrillation and cardiac
arrest are cited to substantiate these experimental findings.
22. Prevention
of Post-Hypercapneic Ventricular Fibrillation in Dogs.
Bernard Goott (by invitation), Fletcher A. Miller (by invitation),
and Owen H. Wangensteen, Minneapolis, Minn.
Previous investigations in our laboratory have
demonstrated that following the cessation of inhalation of 40 per cent carbon
dioxide, many of the dogs died immediately thereafter from ventricular
fibrillation. Since ventricular fibrillation is probably the specific mechanism
underlying the death of most patients dying from acute coronary thrombosis, we
felt that a more concise understanding of the biological changes in association
with fibrillation is indicated. The following studies have been carried out on
dogs using the technique mentioned above for induction of the fibrillation.
Fifteen dogs have had their hearts denervated by
bilateral thoracic sympathectomies. Only one of these animals fibrillated when
exposed to the stimulus described. Conversely 90 per cent of the control
animals were observed to fibrillate under similar circumstances. Data will be
presented concerning the changes in the blood chemistry during these
investigations.
We are currently studying changes in the electrical
fibrillation threshold following sympathectomy and/or hypercapnia. These data
will also be presented.
A preliminary group of experiments has demonstrated
that the fibrillation threshold following acute coronary hgation is raised
after sympathectomy. This group of experiments is being expanded and the
results will be presented.
23. A Method for the Simultaneous Measurement of
Maximum Breathing Capacity, Pulmonary Volumina and Effective Lung Ventilation.
George W. Wright, and Sol Guilford (by invitation), Cleveland, Ohio
The importance of recognizing and quantitating the
impairment caused by
cardio-pulmonary diseases prior to thoracic surgical
procedures has been amply demonstrated. A rapid method (requiring three minutes
or less) for performing the test and calculations to measure the Maximum
Breathing Capacity, Pulmonary Volumina (including Residual Volume) and
Effectiveness of Lung Ventilation simultaneously has been devised. A comparison
of this method to the conventional ones will be made.
24. A
New Foam Plastic Arterial Prosthesis.
Richard W.
Hardy (by invitation), Washington,
D.C.
Based on a study of the physical makeup of human
arteries in regard to tensile strength and stress-strain performance, a new and
previously unreported arterial prosthesis has been developed which closely
resembles the human artery in handling qualities and physical properties.
The prosthesis is made of a newly developed elastomer
foam, a non-plasticized terpolymer. Its internal wall is smooth and it is
easily handled and sutured. The prosthesis can be cut at any angle and conforms
to shape even in flexion creases. Preclotting is unnecessary. It is strong, and
chemical data on the plastic material indicate that it will not lose its
strength on long term implantation or by repeated flexion. Fabrication of
complex shapes is simple and inexpensive.
Tensile strength and tissue reaction studies of the
plastic foam have been underway for more than four months. The abdominal aorta
has been replaced in 15 dogs and long term follow-up will be reported. It is
also being evaluated for use in reconstructive procedures in cardiac surgery.
25. Experimental
Observations on Poststenotic Dilatation.
David L. Bruns (by invitation), John E. Connolly (by invitation),
Emile Holman, and Raymond C. Stofer (by invitation),
San Francisco, Calif.
The frequent finding of poststenotic dilatation in the
low pressure region distal to a vascular stenosis has evoked much speculation
as to its cause. Hoi-man was the first to shed considerable light on the
problem by stressing the importance of considering the physical factors
involved in blood flow through a stenosis.
New discoveries in the field of fluid mechanics have
led us to believe that the presence of murmurs and especially of thrills in the
poststenotic region may be more significant than those forces related to
pulsatile flow. This is because we feel that murmurs, and hence thrills, are
due to rapid and nearly periodic pressure fluctuations in the wake downstream
of a stenosis and as such, constitute forces of sufficient energy to cause
structural fatigue and dilatation of the vessel wall.
To exclude any forces due to flow, thin-walled latex
rubber tubes were filled with water and stoppered at both ends. They were
placed under constant hydrostatic pressure loads. A vibrating blade was
inserted through the center of one stopper. After from seven hours to 120 hours
structural fatigue occurred and dilatation developed in the area of maximum
vibration. However, no dilatation occurred in similar tubes subjected to high
static or grossly fluctuating pressures.
This report demonstrates that a physical basis for
poststenotic dilatation exists. Furthermore, other than a possible congenital
weakness of the vessel wall, thrills are the only factors of sufficient
magnitude which are peculiar to the region beyond the stenosis. It seems
reasonable then that dilatation occurs in a low pressure area, secondary to
vibrational stress.
26. Surgical Management of
Metallic Foreign Bodies in the Pulmonary Artery: Experimental and Clinical
Observations.
Lyman A. Brewer, III, Edward L. King (by
invitation),
Ellsworth E.
Wareham (by invitation) and
Jack M. Farms
(by invitation), Los Angeles, Calif.
The surgical management of a metallic foreign body
lodged in the pulmonary arterial circulation poses a difficult problem to the
surgeon because of the paucity of reports and diversities of opinion in the
medical literature. However, it is probable that this condition is not as rare
as is recorded in the medical literature for we have known of several
unreported cases. Since World War II, potential infection, hemorrhage, emboli
and septicemia have been recommended as indications for removal of the foreign
body. Yet, when the foreign body is asymptomatic and has produced no changes in
the lung, on the chest roentgenogram, the performance of a thoracotomy to
remove this foreign body has been questioned. We have been faced with this
problem clinically and have not been satisfied with our handling of this type
of case. Therefore, a series of animal experiments were undertaken in which
metallic foreign bodies were introduced into the pulmonary and systemic
arteries in a group of mongrel dogs. Fundamental observations over a 20 month
period on the reaction of an artery to a metallic foreign body shows that rapid
growth of the intima holds the foreign body in a protective cocoon. The fate of
the tissue distal to the foreign body depends mainly on the efficiency of the
collateral circulation. This was true for both pulmonary and systemic arteries.
Erosion of the arterial wall was not encountered. Foreign bodies in a branch
pulmonary artery were well tolerated, as compared to those in the main
pulmonary artery itself. Based on this experimental study and the accumulated
clinical experience to date, a plan of treatment is presented.
27. The
Cause of Death Following Cardioangiography.
Raymond C.
Read (by invitation).
Sponsored by Richard L. Varco, Minneapolis, Minn.
X-ray visualization of the heart and great vessels has
proven to be a useful diagnostic procedure in cardiovascular disease. However,
its application has been limited by a small but definite mortality rate
(approximately 2%). The only explanation for this hazard is the proposed role of
either hypersensitivity, allergy, iodism or vascular spasm. The purpose of this
paper is to present experimental evidence suggesting that red cell
agglutination is the main mechanism responsible for the reactions occasionally
observed.
The rapid intravenous administration of 1 cc/kgm of 90%
Hypaque or other widely used organic iodides into the dog was found to be
associated with a phasic pulmonary hypertension. The magnitude of this response
was variable.
A similar transitory increase in pulmonary vascular resistance was
demonstrated in the isolated lung perfused at constant flow. This phenomenon
could only be produced when red cells were present in the perfusate.
The failure of the response to persist in spite of
recirculation suggested an increase in viscosity, rather than a vasomotor
response. This hypothesis was confirmed by direct microscopic examination of
the small vessels in the lung. Agglutination of red cells with plugging of
vascular channels in the lung was seen to follow the injection of concentrated
radio-opaque agents in spite of heparinization. A moving picture illustrating
this phenomenon will be shown.
These findings help to explain why the morbidity of
cardioangiography is known to be greatest in patients with restricted pulmonary
blood flow.
28. Physiological Response of
the Coronary Circulation to Unilateral Pulmonary Artery Ligation.
James B. Littlefield (by invitation), Phyllis R. Ingram (by invitation),
and William H. Muller, Jr., Charlottesville, Va.
Previous studies in dogs with left pulmonary artery
ligation (producing extensive collateral pulmonary circulation) revealed the
inability initially to arrest the heart with potassium for more than 10
minutes. Bronchial artery casts consistently demonstrated plastic (10%) in the
left coronary artery, when injection was made only into the doubly
clamped descending aorta.
A method of investigation was then devised (employing
total cardiopul-monary bypass with aortic and pulmonary artery occlusion) to
separate the left auricular return from the coronary circulation. This
technique completely isolated a short segment of the ascending aorta containing
the coronary ostia. Acute studies in a series of dogs with left pulmonary
artery ligation from 3 to 19 months were investigated and compared with normal
controls. Vascular pressures and flows, oxygen saturation, angiography and
plastic cast studies were made.
RESULTS:
Before Bypass. The
coronary sinus flow was greater in the high collateral flow dogs (controls 40,
others 118 cc/min.).
Total Bypass. The
coronary sinus pressure and flows were the same in both groups but right
auricular flow increased in the dogs with unilateral pulmonary artery ligation
(controls 22, others 60 cc/min.).
Total Bypass, Elective Cardiac Arrest. Pulmonary artery and aorta were occluded. Controls
showed coronary sinus and coronary artery pressure below 7 mm. Hg, with no
coronary sinus flow. Ligated pulmonary artery dogs demonstrated coronary
artery pressures of 44 mm. Hg; right heart flows of 320 cc/min.; left auricular
flows 530 cc/min. (controls 36); and during aortic occlusion without
cardioplegia normal cardiac rhythm continued 23 to 83 minutes (controls 15).
